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Sample records for residual stress results

Investigating Resulting Residual Stresses during Mechanical Forming Process

Science.gov (United States)

Akinlabi, Stephen A.; Fatoba, Olawale S.; Mashinini, Peter M.; Akinlabi, Esther T.

2018-03-01

Most manufacturing processes such as machining, welding, heat treatment, laser forming, laser cladding and, laser metal deposition, etc. are subjected to a form of heat or energy to change the geometrical shape thus changing the inherent engineering and structural properties of the material. These changes often cause the development of locked up stresses referred to as residual stresses as a result of these activities. This study reports on the residual stresses developed due to the mechanical forming process to maintain a suitable structural integrity for the formed components. The result of the analysis through the X-ray diffraction confirmed that residual stresses were induced in the manufactured parts and further revealed that residual stresses were compressive in nature as found in the parent material but with values less than the parent material.
Residual stresses

International Nuclear Information System (INIS)

Sahotra, I.M.

2006-01-01

The principal effect of unloading a material strained into the plastic range is to create a permanent set (plastic deformation), which if restricted somehow, gives rise to a system of self-balancing within the same member or reaction balanced by other members of the structure., known as residual stresses. These stresses stay there as locked-in stresses, in the body or a part of it in the absence of any external loading. Residual stresses are induced during hot-rolling and welding differential cooling, cold-forming and extruding: cold straightening and spot heating, fabrication and forced fitting of components constraining the structure to a particular geometry. The areas which cool more quickly develop residual compressive stresses, while the slower cooling areas develop residual tensile stresses, and a self-balancing or reaction balanced system of residual stresses is formed. The phenomenon of residual stresses is the most challenging in its application in surface modification techniques determining endurance mechanism against fracture and fatigue failures. This paper discusses the mechanism of residual stresses, that how the residual stresses are fanned and what their behavior is under the action of external forces. Such as in the case of a circular bar under limit torque, rectangular beam under limt moment, reclaiming of shafts welds and peening etc. (author)
Residual stresses

International Nuclear Information System (INIS)

Macherauch, E.

1978-01-01

Residual stresses are stresses which exist in a material without the influence of external powers and moments. They come into existence when the volume of a material constantly changes its form as a consequence of mechanical, thermal, and/or chemical processes and is hindered by neighbouring volumes. Bodies with residual stress are in mechanical balance. These residual stresses can be manifested by means of all mechanical interventions disturbing this balance. Acoustical, optical, radiological, and magnetical methods involving material changes caused by residual stress can also serve for determining residual stress. Residual stresses have an ambivalent character. In technical practice, they are feared and liked at the same time. They cause trouble because they can be the cause for unexpected behaviour of construction elements. They are feared since they can cause failure, in the worst case with catastrophical consequences. They are appreciated, on the other hand, because, in many cases, they can contribute to improvements of the material behaviour under certain circumstances. But they are especially liked for their giving convenient and (this is most important) mostly uncontrollable explanations. For only in very few cases we have enough knowledge and possibilities for the objective evaluation of residual stresses. (orig.) [de
Residual stress investigation of copper plate and canister EB-Welds Complementary Results

International Nuclear Information System (INIS)

Gripenberg, H.

2009-03-01

The residual stresses in copper as induced by EB-welding were studied by specimens where the weld had two configurations: either a linear or a circumferential weld. This report contains the residual stress measurements of two plates, containing linear welds, and the full-scale copper lid specimen to which a hollow cylinder section had been joined by a circumferential EB-weld. The residual stress state of the EB-welded copper specimens was investigated by X-ray diffraction (XRD), hole drilling (HD) ring core (RC) and contour method (CM). Three specimens, canister XK010 and plates X251 and X252, were subjected to a thorough study aiming at quantitative determination of the residual stress state in and around the EB-welds using XRD for surface and HD and RC for spatial stress analysis. The CM maps one stress component over a whole cross section. The surface residual stresses measured by XRD represent the machined condition of the copper material. The XRD study showed that the stress changes towards compression close to the weld in the hollow cylinder, which indicates shrinkage in the hoop direction. According to the same analogy, the shrinkage in the axial direction is much smaller. The HD measurements showed that the stress state in the base material is bi-axial and, in terms of von Mises stress, 50 MPa for the plates and 20 MPa for the cylinder part of the canister. The stress state in the EB-welds of all specimens differs clearly from the stress state in the base material being more tensile, with higher magnitudes of von Mises stress in the plate than in the canister welds. The HD and RC results were obtained using linear elastic theory. The RC measurements showed that the maximum principal stress in the BM is close to zero near the surface and it becomes slightly tensile, 10 MPa, deeper under the surface. Welding pushed the general stress state towards tension with the maximum principal stress reaching 50 MPa, deeper than 5 mm below the surface in the weld. The
Residual stress by repair welds

International Nuclear Information System (INIS)

Mochizuki, Masahito; Toyoda, Masao

2003-01-01

Residual stress by repair welds is computed using the thermal elastic-plastic analysis with phase-transformation effect. Coupling phenomena of temperature, microstructure, and stress-strain fields are simulated in the finite-element analysis. Weld bond of a plate butt-welded joint is gouged and then deposited by weld metal in repair process. Heat source is synchronously moved with the deposition of the finite-element as the weld deposition. Microstructure is considered by using CCT diagram and the transformation behavior in the repair weld is also simulated. The effects of initial stress, heat input, and weld length on residual stress distribution are studied from the organic results of numerical analysis. Initial residual stress before repair weld has no influence on the residual stress after repair treatment near weld metal, because the initial stress near weld metal releases due to high temperature of repair weld and then stress by repair weld regenerates. Heat input has an effect for residual stress distribution, for not its magnitude but distribution zone. Weld length should be considered reducing the magnitude of residual stress in the edge of weld bead; short bead induces high tensile residual stress. (author)
Residual stresses and stress corrosion cracking in pipe fittings

International Nuclear Information System (INIS)

Parrington, R.J.; Scott, J.J.; Torres, F.

1994-06-01

Residual stresses can play a key role in the SCC performance of susceptible materials in PWR primary water applications. Residual stresses are stresses stored within the metal that develop during deformation and persist in the absence of external forces or temperature gradients. Sources of residual stresses in pipe fittings include fabrication processes, installation and welding. There are a number of methods to characterize the magnitude and orientation of residual stresses. These include numerical analysis, chemical cracking tests, and measurement (e.g., X-ray diffraction, neutron diffraction, strain gage/hole drilling, strain gage/trepanning, strain gage/section and layer removal, and acoustics). This paper presents 400 C steam SCC test results demonstrating that residual stresses in as-fabricated Alloy 600 pipe fittings are sufficient to induce SCC. Residual stresses present in as-fabricated pipe fittings are characterized by chemical cracking tests (stainless steel fittings tested in boiling magnesium chloride solution) and by the sectioning and layer removal (SLR) technique
Effect of applied stress on the compressive residual stress introduced by laser peening

International Nuclear Information System (INIS)

Sumiya, Rie; Tazawa, Toshiyuki; Narazaki, Chihiro; Saito, Toshiyuki; Kishimoto, Kikuo

2016-01-01

Peening is the process which is able to be generated compressive residual stress and is known to be effective for preventing SCC initiation and improvement of fatigue strength. Laser peening is used for the nuclear power plant components in order to prevent SCC initiation. Although it is reported that the compressive residual stress decreases due to applied stresses under general operating condition, the change of residual stress might be large under excessive loading such as an earthquake. The objectives of this study are to evaluate the relaxation behavior of the compressive residual stress due to laser peening and to confirm the surface residual stress after loading. Therefore laser peened round bar test specimens of SUS316L which is used for the reactor internals of nuclear power plant were loaded at room temperature and elevated temperature and then surface residual stresses were measured by X-ray diffraction method. In the results of this test, it was confirmed that the compressive residual stress remained after applying uniform stress larger than 0.2% proof stress, and the effect of cyclic loading on the residual stress was small. The effect of applying compressive stress on the residual stress relaxation was confirmed to be less than that of applying tensile stress. Plastic deformation through a whole cross section causes the change in the residual stress distribution. As a result, the surface compressive residual stress is released. It was shown that the effect of specimen size on residual stress relaxation and the residual stress relaxation behavior in the stress concentration region can be explained by assumed stress relaxation mechanism. (author)
Evaluation of stress intensity factors due to welding residual stresses for circumferential cracked pipes

International Nuclear Information System (INIS)

Oh, Chang-Young; Kim, Yun-Jae; Oh, Young-Jin; Kim, Jong-Sung; Song, Tae-Kwang; Kim, Yong-Beum

2013-01-01

To investigate the applicability of existing methods to estimate stress intensity factors due to welding residual stresses, comparisons with finite element (FE) solutions are made for two types of generic welding residual stress profiles, generated by simulating repair welds. It is found that fitting residual stresses over the crack depth using third-order polynomials gives good estimates of stress intensity factors but fitting over the entire thickness can result in inaccurate estimates even with fourth-order polynomials. Noting that welding residual stresses are often determined from FE analyses, linearization of residual stresses to estimate stress intensity factors is proposed. Comparison with FE solutions shows good agreements. -- Highlights: ► Applicability of K estimation methods is investigated for welding residual stresses. ► Two types of generic residual stress profiles with repair welds are considered. ► Fitting residual stresses over the crack depth gives good estimates of K. ► A method to estimate K by linearising residual stress profiles is proposed
Residual stress in a thick section high strength T-butt weld

International Nuclear Information System (INIS)

Pearce, S.V.; Linton, V.M.; Oliver, E.C.

2008-01-01

Residual stresses in a structure are generated as a result of the various fabrication and welding processes used to make the component. Being able to quantify these residual stresses is a key step in determining the continuing integrity of a structure in service. In this work, the residual stresses around a high strength, quenched and tempered steel T-butt web to curved plate weld have been measured using neutron strain scanning. The results show that the residual stresses near the weld were dominated by the welding residual stresses, while the stresses further from the weld were dominated by the bending residual stresses. The results suggest that the combination of welding-induced residual stress and significant pre-welding residual stress, as in the case of a thick bent section of plate can significantly alter the residual stress profile from that in a flat plate
Prediction of residual stress distributions due to surface machining and welding and crack growth simulation under residual stress distribution

International Nuclear Information System (INIS)

Ihara, Ryohei; Katsuyama, JInya; Onizawa, Kunio; Hashimoto, Tadafumi; Mikami, Yoshiki; Mochizuki, Masahito

2011-01-01

Research highlights: → Residual stress distributions due to welding and machining are evaluated by XRD and FEM. → Residual stress due to machining shows higher tensile stress than welding near the surface. → Crack growth analysis is performed using calculated residual stress. → Crack growth result is affected machining rather than welding. → Machining is an important factor for crack growth. - Abstract: In nuclear power plants, stress corrosion cracking (SCC) has been observed near the weld zone of the core shroud and primary loop recirculation (PLR) pipes made of low-carbon austenitic stainless steel Type 316L. The joining process of pipes usually includes surface machining and welding. Both processes induce residual stresses, and residual stresses are thus important factors in the occurrence and propagation of SCC. In this study, the finite element method (FEM) was used to estimate residual stress distributions generated by butt welding and surface machining. The thermoelastic-plastic analysis was performed for the welding simulation, and the thermo-mechanical coupled analysis based on the Johnson-Cook material model was performed for the surface machining simulation. In addition, a crack growth analysis based on the stress intensity factor (SIF) calculation was performed using the calculated residual stress distributions that are generated by welding and surface machining. The surface machining analysis showed that tensile residual stress due to surface machining only exists approximately 0.2 mm from the machined surface, and the surface residual stress increases with cutting speed. The crack growth analysis showed that the crack depth is affected by both surface machining and welding, and the crack length is more affected by surface machining than by welding.
Sustainability of compressive residual stress by stress improvement processes

International Nuclear Information System (INIS)

Nishikawa, Satoru; Okita, Shigeru; Yamaguchi, Atsunori

2013-01-01

Stress improvement processes are countermeasures against stress corrosion cracking in nuclear power plant components. It is necessary to confirm whether compressive residual stress induced by stress improvement processes can be sustained under operation environment. In order to evaluate stability of the compressive residual stress in 60-year operating conditions, the 0.07% cyclic strains of 200 times at 593 K were applied to the welded specimens, then a thermal aging treatment for 1.66x10 6 s at 673 K was carried out. As the result, it was confirmed that the compressive residual stresses were sustained on both surfaces of the dissimilar welds of austenitic stainless steel (SUS316L) and nickel base alloy (NCF600 and alloy 182) processed by laser peening (LP), water jet peening (WJP), ultrasonic shot peening (USP), shot peening (SP) and polishing under 60-year operating conditions. (author)
Effectiveness of stress release geometries on reducing residual stress in electroforming metal microstructure

Science.gov (United States)

Song, Chang; Du, Liqun; Zhao, Wenjun; Zhu, Heqing; Zhao, Wen; Wang, Weitai

2018-04-01

Micro electroforming, as a mature micromachining technology, is widely used to fabricate metal microdevices in micro electro mechanical systems (MEMS). However, large residual stress in the local positions of the micro electroforming layer often leads to non-uniform residual stress distributions, dimension accuracy defects and reliability issues during fabrication of the metal microdevice. To solve this problem, a novel design method of presetting stress release geometries in the topological structure of the metal microstructure is proposed in this paper. First, the effect of stress release geometries (circular shape, annular groove shape and rivet shape) on the residual stress in the metal microstructure was investigated by finite element modeling (FEM) analysis. Two evaluation parameters, stress concentration factor K T and stress non-uniformity factor δ were calculated. The simulation results show that presetting stress release geometries can effectively reduce and homogenize the residual stress in the metal microstructures were measured metal microstructure. By combined use with stress release geometries of annular groove shape and rivet shape, the stress concentration factor K T and the stress non-uniformity factor δ both decreased at a maximum of 49% and 53%, respectively. Meanwhile, the average residual stress σ avg decreased at a maximum of 20% from -292.4 MPa to -232.6 MPa. Then, micro electroforming experiments were carried out corresponding to the simulation models. The residual stresses in the metal microstructures were measured by micro Raman spectroscopy (MRS) method. The results of the experiment proved that the stress non-uniformity factor δ and the average residual stress σ avg also decreased at a maximum with the combination use of annular groove shape and rivet shape stress release geometries, which is in agreement with the results of FEM analysis. The stress non-uniformity factor δ has a maximum decrease of 49% and the
Residual stress studies of austenitic and ferritic steels

International Nuclear Information System (INIS)

Chrenko, R.M.

1978-01-01

Residual studies have been made on austenitic and ferritic steels of the types used as structural materials. The residual stress results presented here will include residual stress measurements in the heat-affected zone on butt welded Type 304 stainless steel pipes, and the stresses induced in Type 304 austenitic stainless steel and Type A508 ferritic steel by several surface preparations. Such surface preparation procedures as machining and grinding can induce large directionality effects in the residual stresses determined by X-ray techniques and some typical data will be presented. A brief description is given of the mobile X-ray residual stress apparatus used to obtain most of the data in these studies. (author)
Design of specimen for weld residual stress simulation

International Nuclear Information System (INIS)

Kim, Jin Weon; Park, Jong Sun; Lee, Kyung Soo

2008-01-01

The objective of this study is to design a laboratory specimen for simulating residual stress of circumferential butt welding of pipe. Specimen type and method for residual stress generation were proposed based on the review of prior studies and parametric finite element simulation. To prove the proposed specimen type and loading method, the residual stress was generated using the designed specimen by applying proposed method and was measured. The measured residual stress using X-ray diffraction reasonably agreed with the results of finite element simulation considered in the specimen design. Comparison of residual strains measured at several locations of specimen and given by finite element simulation also showed good agreement. Therefore, it is indicated that the designed specimen can reasonably simulate the residual stress of circumferential butt welding of pipe
Residual stresses around Vickers indents

International Nuclear Information System (INIS)

Pajares, A.; Guiberteau, F.; Steinbrech, R.W.

1995-01-01

The residual stresses generated by Vickers indentation in brittle materials and their changes due to annealing and surface removal were studied in 4 mol% yttria partially stabilized zirconia (4Y-PSZ). Three experimental methods to gain information about the residual stress field were applied: (i) crack profile measurements based on serial sectioning, (ii) controlled crack propagation in post indentation bending tests and (iii) double indentation tests with smaller secondary indents located around a larger primary impression. Three zones of different residual stress behavior are deduced from the experiments. Beneath the impression a crack free spherical zone of high hydrostatic stresses exists. This core zone is followed by a transition regime where indentation cracks develop but still experience hydrostatic stresses. Finally, in an outward third zone, the crack contour is entirely governed by the tensile residual stress intensity (elastically deformed region). Annealing and surface removal reduce this crack driving stress intensity. The specific changes of the residual stresses due to the post indentation treatments are described and discussed in detail for the three zones
Residual stress concerns in containment analysis

International Nuclear Information System (INIS)

Costantini, F.; Kulak, R. F.; Pfeiffer, P. A.

1997-01-01

The manufacturing of steel containment vessels starts with the forming of flat plates into curved plates. A steel containment structure is made by welding individual plates together to form the sections that make up the complex shaped vessels. The metal forming and welding process leaves residual stresses in the vessel walls. Generally, the effect of metal forming residual stresses can be reduced or virtually eliminated by thermally stress relieving the vesseL In large containment vessels this may not be practical and thus the residual stresses due to manufacturing may become important. The residual stresses could possibly tiect the response of the vessel to internal pressurization. When the level of residual stresses is significant it will affect the vessel's response, for instance the yielding pressure and possibly the failure pressure. The paper will address the effect of metal forming residual stresses on the response of a generic pressure vessel to internal pressurization. A scoping analysis investigated the effect of residual forming stresses on the response of an internally pressurized vessel. A simple model was developed to gain understanding of the mechanics of the problem. Residual stresses due to the welding process were not considered in this investigation
Residual Stress Analysis Based on Acoustic and Optical Methods

Directory of Open Access Journals (Sweden)

Sanichiro Yoshida

2016-02-01

Full Text Available Co-application of acoustoelasticity and optical interferometry to residual stress analysis is discussed. The underlying idea is to combine the advantages of both methods. Acoustoelasticity is capable of evaluating a residual stress absolutely but it is a single point measurement. Optical interferometry is able to measure deformation yielding two-dimensional, full-field data, but it is not suitable for absolute evaluation of residual stresses. By theoretically relating the deformation data to residual stresses, and calibrating it with absolute residual stress evaluated at a reference point, it is possible to measure residual stresses quantitatively, nondestructively and two-dimensionally. The feasibility of the idea has been tested with a butt-jointed dissimilar plate specimen. A steel plate 18.5 mm wide, 50 mm long and 3.37 mm thick is braze-jointed to a cemented carbide plate of the same dimension along the 18.5 mm-side. Acoustoelasticity evaluates the elastic modulus at reference points via acoustic velocity measurement. A tensile load is applied to the specimen at a constant pulling rate in a stress range substantially lower than the yield stress. Optical interferometry measures the resulting acceleration field. Based on the theory of harmonic oscillation, the acceleration field is correlated to compressive and tensile residual stresses qualitatively. The acoustic and optical results show reasonable agreement in the compressive and tensile residual stresses, indicating the feasibility of the idea.
X-ray measurement of residual stress on bolt threads

International Nuclear Information System (INIS)

Hagiwara, Masaya; Nakahara, Kanefumi; Yoshimoto, Isamu.

1989-01-01

This study deals with X-ray measurement of residual stress at the local area around the thread root of a bolt. Residual stress in the 0.5 mm x 5 mm area was measured using a method of stepped scanning and parabolic approximation. The conditions of measurement had been determined and evaluated through the preliminary measurement of compressive stress acting on the cylindrical surface. Furthermore, the fatigue strength estimated by applying the residual stress data to the previously presented hypothesis was compared with the experimental results. The main conclusions obtained were as follows: (1) The residual stress in a relatively small area on the cylindrical surface with large curvature can be measured by X-ray using a method of stepped scanning and parabolic approximation; (2) The compressive residual stress measured at the thread root was larger for the bolt manufactured by thread rolling after heat treatment than for one manufactured by thread rolling before heat treatment; (3) The distribution of residual stress along the axial direction from the thread root to the portion under crest did not represent remarkable change in its value; (4) The residual stress of a bolt was somewhat decreased by fatigue loading on the condition of low mean stress; (5) The fatigue strength estimated using residual stress data showed the tendency of experimental results well. (author)
Effect of residual stresses on hydrogen permeation in iron

International Nuclear Information System (INIS)

Mouanga, M.; Bercot, P.; Takadoum, J.

2010-01-01

The effect of residual stresses on electrochemical permeation in iron membrane was investigated. Four thermal and mechanical treatments were chosen to obtain different surface states in relation to the residual stresses. Residual stresses were determined by X-ray diffraction (XRD) using the Macherauch and Mueller method. The results were completed by the microhardness measurements. For all iron membranes, compressive residual stresses were obtained. Electrochemical permeation experiments using a Devanathan and Stachurski cell were employed to determine the hydrogen permeation behaviour of the various iron membranes. The latter was charged with hydrogen by galvanostatic cathodic polarization in 0.1 M NaOH at 25 deg. C. The experimental results revealed that hydrogen permeation rate increases with increasing residual stresses introduced in iron membranes.
Residual stress analysis in reactor pressure vessel attachments

International Nuclear Information System (INIS)

Dexter, R.J.; Pont, D.

1991-08-01

Residual stresses in cladding and welded attachments could contribute to the problem of stress-corrosion cracking in boiling-water reactors (BWR). As part of a larger program aimed at quantifying residual stress in BWR components, models that would be applicable for predicting residual stress in BWR components are reviewed and documented. The review includes simple methods of estimating residual stresses as well as advanced finite-element software. In general, simple methods are capable of predicting peak magnitudes of residual stresses but are incapable of adequately characterizing the distribution of residual stresses. Ten groups of researchers using finite-element software are reviewed in detail. For each group, the assumptions of the model, possible simplifications, material property data, and specific applications are discussed. The most accurate results are obtained when a metallurgical simulation is performed, transformation plasticity effects are included, and the heating and cooling parts of the welding thermal cycle are simulated. Two models are identified which can provide these features. The present state of these models and the material property data available in the literature are adequate to quantify residual stress in BWR components

A review of residual stress analysis using thermoelastic techniques

Energy Technology Data Exchange (ETDEWEB)

Robinson, A F; Dulieu-Barton, J M; Quinn, S [University of Southampton, School of Engineering Sciences, Highfield, Southampton, SO17 1BJ (United Kingdom); Burguete, R L [Airbus UK Ltd., New Filton House, Filton, Bristol, BS99 7AR (United Kingdom)

2009-08-01

Thermoelastic Stress Analysis (TSA) is a full-field technique for experimental stress analysis that is based on infra-red thermography. The technique has proved to be extremely effective for studying elastic stress fields and is now well established. It is based on the measurement of the temperature change that occurs as a result of a stress change. As residual stress is essentially a mean stress it is accepted that the linear form of the TSA relationship cannot be used to evaluate residual stresses. However, there are situations where this linear relationship is not valid or departures in material properties due to manufacturing procedures have enabled evaluations of residual stresses. The purpose of this paper is to review the current status of using a TSA based approach for the evaluation of residual stresses and to provide some examples of where promising results have been obtained.
A review of residual stress analysis using thermoelastic techniques

International Nuclear Information System (INIS)

Robinson, A F; Dulieu-Barton, J M; Quinn, S; Burguete, R L

2009-01-01

Thermoelastic Stress Analysis (TSA) is a full-field technique for experimental stress analysis that is based on infra-red thermography. The technique has proved to be extremely effective for studying elastic stress fields and is now well established. It is based on the measurement of the temperature change that occurs as a result of a stress change. As residual stress is essentially a mean stress it is accepted that the linear form of the TSA relationship cannot be used to evaluate residual stresses. However, there are situations where this linear relationship is not valid or departures in material properties due to manufacturing procedures have enabled evaluations of residual stresses. The purpose of this paper is to review the current status of using a TSA based approach for the evaluation of residual stresses and to provide some examples of where promising results have been obtained.
Residual stress in Ni-W electrodeposits

DEFF Research Database (Denmark)

Mizushima, Io; Tang, Peter Torben; Hansen, Hans Nørgaard

2006-01-01

In the present work, the residual stress in Ni–W layers electrodeposited from electrolytes based on NiSO4 and Na2WO4, is investigated. Citrate, glycine and triethanolamine were used as complexing agents, enabling complex formation between the nickel ion and tungstate. The results show that the type...... of complexing agent and the current efficiency have an influence on the residual stress. In all cases, an increase in tensile stress in the deposit with time after deposition was observed. Pulse plating could improve the stress level for the electrolyte containing equal amounts of citrate...
Residual stresses in Inconel 718 engine disks

Directory of Open Access Journals (Sweden)

Dahan Yoann

2014-01-01

Full Text Available Aubert&Duval has developed a methodology to establish a residual stress model for Inconel 718 engine discs. To validate the thermal, mechanical and metallurgical parts of the model, trials on lab specimens with specific geometry were carried out. These trials allow a better understanding of the residual stress distribution and evolution during different processes (quenching, ageing, machining. A comparison between experimental and numerical results reveals the residual stresses model accuracy. Aubert&Duval has also developed a mechanical properties prediction model. Coupled with the residual stress prediction model, Aubert&Duval can now propose improvements to the process of manufacturing in Inconel 718 engine disks. This model enables Aubert&Duval customers and subcontractors to anticipate distortions issues during machining. It could also be usedt to optimise the engine disk life.
Residual stress measurement of large scaled welded pipe using neutron diffraction method. Effect of SCC crack propagation and repair weld on residual stress distribution

International Nuclear Information System (INIS)

Suzuki, Hiroshi; Katsuyama, Jinya; Tobita, Tohru; Morii, Yukio

2011-01-01

The RESA-1 neutron engineering diffractometer in the JRR-3 (Japan Research Reactor No.3) at the Japan Atomic Energy Agency, which is used for stress measurements, was upgraded to realize residual stress measurements of large scaled mechanical components. A series of residual stress measurements was made to obtain through-thickness residual stress distributions in a Type 304 stainless steel butt-welded pipe of 500A-sch.80 using the upgraded RESA-1 diffractometer. We evaluated effects of crack propagation such as stress corrosion cracking (SCC) and a part-circumference repair weld on the residual stress distributions induced by girth welding. Measured residual stress distributions near original girth weld revealed good agreement with typical results shown in some previous works using finite element method, deep hole drilling as well as neutron diffraction. After introducing a mock crack with 10 mm depth in the heat affected zone on the inside wall of the pipe by electro discharge machining, the axial residual stresses were found to be released in the part of the mock crack. However, changes in the through-wall bending stress component and the self-equilibrated stress component were negligible and hence the axial residual stress distribution in the ligament was remained in the original residual stresses near girth weld without the mock crack. Furthermore, changes in hoop and radial residual stress were also small. The residual stress distributions after a part repair welding on the outer circumference of the girth weld were significantly different from residual stress distributions near the original girth weld. The through-thickness average axial residual stress was increased due to increase of the tensile membrane stress and mitigation of the bending stress after repair welding. Throughout above studies, we evidenced that the neutron diffraction technique is useful and powerful tool for measuring residual stress distributions in large as well as thick mechanical
Residual Stress Testing of Outer 3013 Containers

International Nuclear Information System (INIS)

Dunn, K.

2004-01-01

A Gas Tungsten Arc Welded (GTAW) outer 3013 container and a laser welded outer 3013 container have been tested for residual stresses according to the American Society for Testing Materials (ASTM) Standard G-36-94 [1]. This ASTM standard describes a procedure for conducting stress-corrosion cracking tests in boiling magnesium chloride (MgCl2) solution. Container sections in both the as-fabricated condition as well as the closure welded condition were evaluated. Significantly large residual stresses were observed in the bottom half of the as-fabricated container, a result of the base to can fabrication weld because through wall cracks were observed perpendicular to the weld. This observation indicates that regardless of the closure weld technique, sufficient residual stresses exist in the as-fabricated container to provide the stress necessary for stress corrosion cracking of the container, at the base fabrication weld. Additionally, sufficiently high residual stresses were observed in both the lid and the body of the GTAW as well as the laser closure welded containers. The stresses are oriented perpendicular to the closure weld in both the container lid and the container body. Although the boiling MgCl2 test is not a quantitative test, a comparison of the test results from the closure welds shows that there are noticeably more through wall cracks in the laser closure welded container than in the GTAW closure welded container
A proposed residual stress model for oblique turning

International Nuclear Information System (INIS)

Elkhabeery, M. M.

2001-01-01

A proposed mathematical model is presented for predicting the residual stresses caused by turning. Effects of change in tool free length, cutting speed, feed rate, and the tensile strength of work piece material on the maximum residual stress are investigated. The residual stress distribution in the surface region due to turning under unlubricated condition is determined using a deflection etching technique. To reduce the number of experiments required and build the mathematical model for these variables, Response Surface Methodology (RSM) is used. In addition, variance analysis and an experimental check are conducted to determine the prominent parameters and the adequacy of the model. The results show that the tensile stress of the work piece material, cutting speed, and feed rate have significant effects on the maximum residual stresses. The proposed model, that offering good correlation between the experimental and predicted results, is useful in selecting suitable cutting parameters for the machining of different materials. (author)
Dependence of magnetic permeability on residual stresses in alloyed steels

Directory of Open Access Journals (Sweden)

E. Hristoforou

2018-04-01

Full Text Available A method for the monitoring of residual stress distribution in steels has been developed based on non-destructive surface magnetic permeability measurements. In order to investigate the potential utilization of the magnetic method in evaluating residual stresses, the magnetic calibration curves of various ferromagnetic alloyed steels’ grade (AISI 4140, TRIP and Duplex were examined. X-Ray diffraction technique was used for determining surface residual stress values. The overall measurement results have shown that the residual stress determined by the magnetic method was in good agreement with the diffraction results. Further experimental investigations are required to validate the preliminary results and to verify the presence of a unique normalized magnetic stress calibration curve.
Dependence of magnetic permeability on residual stresses in alloyed steels

Science.gov (United States)

Hristoforou, E.; Ktena, A.; Vourna, P.; Argiris, K.

2018-04-01

A method for the monitoring of residual stress distribution in steels has been developed based on non-destructive surface magnetic permeability measurements. In order to investigate the potential utilization of the magnetic method in evaluating residual stresses, the magnetic calibration curves of various ferromagnetic alloyed steels' grade (AISI 4140, TRIP and Duplex) were examined. X-Ray diffraction technique was used for determining surface residual stress values. The overall measurement results have shown that the residual stress determined by the magnetic method was in good agreement with the diffraction results. Further experimental investigations are required to validate the preliminary results and to verify the presence of a unique normalized magnetic stress calibration curve.
Estimation of stress intensity factors for circumferential cracked pipes under welding residual stress filed

International Nuclear Information System (INIS)

Oh, Chang Young; Kim, Yun Jae; Oh, Young Jin; Song, Tae Kwang; Kim, Yong Beum; Oh, Young Jin; Song, Tae Kwang; Kim, Yong Beum

2012-01-01

Recently, stress corrosion cracking(SCC) have been found in dissimilar metal welds of nozzles in some pressurized water reactors and on low carbon stainless steel piping systems of boiling water reactors. The important factor of SCC is the residual stress field caused by weld. For the evaluation of crack growth analysis due to SCC, stress intensity factor under a residual stress field should be estimated. Several solutions for stress intensity factor under residual stress field were recommended in flaw assessment codes such as the American Society of Mechanical Engineers (ASME) Section XI, R6, American Petroleum Institute (API579). Some relevant works have been studied. Dong et al. evaluated stress intensity factors in welded structures. Miyazaki et al. estimated stress intensity factors of surface crack in simple stress fields. This paper presents a simple method to estimate stress intensity factors in welding residual stress field. For general application, results of structure integrity assessment codes KI solutions were compared Finite element analyses of welding simulation and cracked pipes are described. Comparison results of KI solutions and proposed simplified solution are presented in the works
Neutron residual stress measurements in linepipe

International Nuclear Information System (INIS)

Law, Michael; Gnaepel-Herold, Thomas; Luzin, Vladimir; Bowie, Graham

2006-01-01

Residual stresses in gas pipelines are generated by manufacturing and construction processes and may affect the subsequent pipe integrity. In the present work, the residual stresses in eight samples of linepipe were measured by neutron diffraction. Residual stresses changed with some coating processes. This has special implications in understanding and mitigating stress corrosion cracking, a major safety and economic problem in some gas pipelines
Evaluation of residual stress in sputtered tantalum thin-film

Energy Technology Data Exchange (ETDEWEB)

Al-masha’al, Asa’ad, E-mail: asaad.al@ed.ac.uk; Bunting, Andrew; Cheung, Rebecca

2016-05-15

Highlights: • Tantalum thin-films have been deposited by DC magnetron sputtering system. • Thin-film stress is observed to be strongly influenced by sputtering pressure. • Transition towards the compressive stress is ascribed to the annealing at 300 °C. • Expose thin-film to air ambient or ion bombardment lead to a noticeable change in the residual stress. - Abstract: The influence of deposition conditions on the residual stress of sputtered tantalum thin-film has been evaluated in the present study. Films have been deposited by DC magnetron sputtering and curvature measurement method has been employed to calculate the residual stress of the films. Transitions of tantalum film stress from compressive to tensile state have been observed as the sputtering pressure increases. Also, the effect of annealing process at temperature range of 90–300 °C in oxygen ambient on the residual stress of the films has been studied. The results demonstrate that the residual stress of the films that have been deposited at lower sputtering pressure has become more compressive when annealed at 300 °C. Furthermore, the impact of exposure to atmospheric ambient on the tantalum film stress has been investigated by monitoring the variation of the residual stress of both annealed and unannealed films over time. The as-deposited films have been exposed to pure Argon energy bombardment and as result, a high compressive stress has been developed in the films.
Residual-stress measurements

Energy Technology Data Exchange (ETDEWEB)

Ezeilo, A N; Webster, G A [Imperial College, London (United Kingdom); Webster, P J [Salford Univ. (United Kingdom)

1997-04-01

Because neutrons can penetrate distances of up to 50 mm in most engineering materials, this makes them unique for establishing residual-stress distributions non-destructively. D1A is particularly suited for through-surface measurements as it does not suffer from instrumental surface aberrations commonly found on multidetector instruments, while D20 is best for fast internal-strain scanning. Two examples for residual-stress measurements in a shot-peened material, and in a weld are presented to demonstrate the attractive features of both instruments. (author).
Residual stress analysis of drive shafts after induction hardening

Energy Technology Data Exchange (ETDEWEB)

Lemos, Guilherme Vieira Braga; Rocha, Alexandre da Silva; Nunes, Rafael Menezes, E-mail: lemos_gl@yahoo.com.br [Universidade Federal do Rio Grande do Sul (UFRS), Porto Algre, RS (Brazil); Hirsch, Thomas Karl [Stiftung Institut für Werkstofftechnik (IWT), Bremen (Germany)

2014-08-15

Typically, for automotive shafts, shape distortion manifests itself in most cases after the induction hardening by an effect known as bending. The distortion results in a boost of costs, especially due to machining parts in the hardened state to fabricate its final tolerances. In the present study, residual stress measurements were carried out on automotive drive shafts made of DIN 38B3 steel. The samples were selected in consequence of their different distortion properties by an industrial manufacturing line. One tested shaft was straightened, because of the considerable dimensional variation and the other one not. Firstly, the residual stress measurements were carried out by using a portable diffractometer, in order to avoid cutting the shafts and evaluate the original state of the stresses, and afterwards a more detailed analysis was realized by a conventional stationary diffractometer. The obtained results presented an overview of the surface residual stress profiles after induction hardening and displayed the influence of the straightening process on the redistribution of residual stresses. They also indicated that the effects of the straightening in the residual stresses cannot be neglected. (author)
Compressive residual stresses as a preventive measure against stress corrosion cracking on turbine components

International Nuclear Information System (INIS)

Berger, C.; Ewald, J.; Fischer, K.; Gruendler, O.; Potthast, E.; Stuecker, E.; Winzen, G.

1987-01-01

Disk type low pressure turbine rotors have been designed for a large variety of power plant applications. Developing disk type rotors required a concerted effort to design a shaft/disk shrink fit with a minimum of tensile stress concentrations in order to aim for the lowest possible susceptibility to corrosive attack, i.e. stress corrosion cracking. As a result of stresses, the regions of greatest concern are the shrink fit boundaries and the keyways of turbine disks. These stresses are caused by service loading, i.e. centrifugal and shrinkage stresses and by manufacturing procedure, i.e. residual stresses. The compressive residual stresses partly compensate the tensile service stresses so that an increase of compressive residual stresses decreases the whole stress state of the component. Special manufacturing procedures, e.g. accelerated cooling after tempering can induce compressive residual stresses up to about 400 MPa in the hub bore region of turbine disk
Application of laser interferometry for assessment of surface residual stress by determination of stress-free state

International Nuclear Information System (INIS)

Kim, Dong Won; Kwon, Dong Il; Lee, Nak Kyu; Choi, Tae Hoon; Na, Kyoung Hoan

2003-01-01

The total relaxed stress in annealing and the thermal strain/stress were obtained from the identification of the residual stress-free state using Electronic Speckle Pattern Interferometry (ESPI). The residual stress fields in case of both single and film/substrate systems were modeled using the thermo-elastic theory and the relationship between relaxed stresses and displacements. We mapped the surface residual stress fields on the indented bulk Cu and the 0.5 μm Au film by ESPI. In indented Cu, the normal and shear residual stress are distributed over -1.7 GPa to 700 MPa and -800 GPa to 600 MPa respectively around the indented point and in deposited Au film on Si wafer, the tensile residual stress is uniformly distributed on the Au film from 500 MPa to 800 MPa. Also we measured the residual stress by the X-Ray Diffractometer (XRD) for the verification of above residual stress results by ESPI
Residual Stresses and Other Properties of Teardrops

Energy Technology Data Exchange (ETDEWEB)

Stroud, Mary Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Veirs, Douglas Kirk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Berg, John M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hill, Mary Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rios, Daniel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Duque, Juan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-07-26

The Department of Energy’s 3013 Standard for packaging plutonium-bearing materials for storage up to fifty years specifies a minimum of two individually welded, nested containers herein referred to as the 3013 outer and the 3013 inner.1 Stress corrosion cracking (SCC) is a potential failure mechanism for 3013 inner containers.2,3 The bagless transfer container (BTC), a 3013 inner container used by Hanford and Savanna River Site (SRS) made from 304L stainless steel (SS), poses the greatest concern for SCC.4,5 The Surveillance and Monitoring Program (SMP) use stressed metal samples known as teardrops as screening tools in SCC studies to evaluate factors that could result in cracks in the 3013 containers.6,7 This report provides background information on the teardrops used in the Los Alamos National Laboratory (LANL) SMP studies including method of construction, composition and variability. In addition, the report discusses measurements of residual stresses in teardrops and compares the results with residual stresses in BTCs reported previously.4 Factors affecting residual stresses, including teardrop dimensions and surface finish, are also discussed.
Residual stress characterization of steel TIG welds by neutron diffraction and by residual magnetic stray field mappings

Science.gov (United States)

Stegemann, Robert; Cabeza, Sandra; Lyamkin, Viktor; Bruno, Giovanni; Pittner, Andreas; Wimpory, Robert; Boin, Mirko; Kreutzbruck, Marc

2017-03-01

The residual stress distribution of tungsten inert gas welded S235JRC+C plates was determined by means of neutron diffraction (ND). Large longitudinal residual stresses with maxima around 600 MPa were found. With these results as reference, the evaluation of residual stress with high spatial resolution GMR (giant magneto resistance) sensors was discussed. The experiments performed indicate a correlation between changes in residual stresses (ND) and the normal component of local residual magnetic stray fields (GMR). Spatial variations in the magnetic field strength perpendicular to the welds are in the order of the magnetic field of the earth.
Analytical and Experimental Study of Residual Stresses in CFRP

Directory of Open Access Journals (Sweden)

Chia-Chin Chiang

2013-01-01

Full Text Available Fiber Bragg Grating sensors (FBGs have been utilized in various engineering and photoelectric fields because of their good environment tolerance. In this research, residual stresses of carbon fiber reinforced polymer composites (CFRP were studied using both experimental and analytical approach. The FBGs were embedded inside middle layers of CFRP to study the formation of residual stress during curing process. Finite element analysis was performed using ABAQUS software to simulate the CFRP curing process. Both experimental and simulation results showed that the residual stress appeared during cooling process and the residual stresses could be released when the CFRP was machined to a different shape.
Residual stress improving method for reactor structural component and residual stress improving device therefor

Energy Technology Data Exchange (ETDEWEB)

Enomoto, Kunio; Otaka, Masahiro; Kurosawa, Koichi; Saito, Hideyo; Tsujimura, Hiroshi; Tamai, Yasukata; Urashiro, Keiichi; Mochizuki, Masato

1996-09-03

The present invention is applied to a BWR type reactor, in which a high speed jetting flow incorporating cavities is collided against the surface of reactor structural components to form residual compression stresses on the surface layer of the reactor structural components thereby improving the stresses on the surface. Namely, a water jetting means is inserted into the reactor container filled with reactor water. Purified water is pressurized by a pump and introduced to the water jetting means. The purified water jetted from the water jetting means and entraining cavities is abutted against the surface of the reactor structural components. With such procedures, since the purified water is introduced to the water jetting means by the pump, the pump is free from contamination of radioactive materials. As a result, maintenance and inspection for the pump can be facilitated. Further, since the purified water injection flow entraining cavities is abutted against the surface of the reactor structural components being in contact with reactor water, residual compression stresses are exerted on the surface of the reactor structural components. As a result, occurrence of stress corrosion crackings of reactor structural components is suppressed. (I.S.)

Residual stress improving method for reactor structural component and residual stress improving device therefor

International Nuclear Information System (INIS)

Enomoto, Kunio; Otaka, Masahiro; Kurosawa, Koichi; Saito, Hideyo; Tsujimura, Hiroshi; Tamai, Yasukata; Urashiro, Keiichi; Mochizuki, Masato.

1996-01-01

The present invention is applied to a BWR type reactor, in which a high speed jetting flow incorporating cavities is collided against the surface of reactor structural components to form residual compression stresses on the surface layer of the reactor structural components thereby improving the stresses on the surface. Namely, a water jetting means is inserted into the reactor container filled with reactor water. Purified water is pressurized by a pump and introduced to the water jetting means. The purified water jetted from the water jetting means and entraining cavities is abutted against the surface of the reactor structural components. With such procedures, since the purified water is introduced to the water jetting means by the pump, the pump is free from contamination of radioactive materials. As a result, maintenance and inspection for the pump can be facilitated. Further, since the purified water injection flow entraining cavities is abutted against the surface of the reactor structural components being in contact with reactor water, residual compression stresses are exerted on the surface of the reactor structural components. As a result, occurrence of stress corrosion crackings of reactor structural components is suppressed. (I.S.)
Residual stress relief in MAG welded joints of dissimilar steels

International Nuclear Information System (INIS)

Seodek, P.; Brozda, J.; Wang, L.; Withers, P.J.

2003-01-01

This paper addresses the relief of residual stress in welded joints between austenitic and non-alloyed ferritic-pearlitic steels. A series of similar and dissimilar steel joints based on the 18G2A (ferritic-pearlitic) and 1H18N10T (austenitic) steels were produced, some of which were stress relieved by annealing and some by mechanical prestressing. For the as-welded and stress relieved test joints the residual stresses were measured by trepanning. To aid the interpretation of these results, 2D plane stress finite element analysis has been performed to simulate the residual stress relieving methods. Analysis of the results has shown that thermal stress relieving of welded joints between dissimilar steels is not effective and may even increase residual stresses, due to the considerable difference in thermal expansion of the joined steels. It was found that, for the loads imposed, the effectiveness of the mechanical stress relieving of dissimilar steel welded joints was much lower than that of similar steel joints
Prediction of residual stress using explicit finite element method

Directory of Open Access Journals (Sweden)

W.A. Siswanto

2015-12-01

Full Text Available This paper presents the residual stress behaviour under various values of friction coefficients and scratching displacement amplitudes. The investigation is based on numerical solution using explicit finite element method in quasi-static condition. Two different aeroengine materials, i.e. Super CMV (Cr-Mo-V and Titanium alloys (Ti-6Al-4V, are examined. The usage of FEM analysis in plate under normal contact is validated with Hertzian theoretical solution in terms of contact pressure distributions. The residual stress distributions along with normal and shear stresses on elastic and plastic regimes of the materials are studied for a simple cylinder-on-flat contact configuration model subjected to normal loading, scratching and followed by unloading. The investigated friction coefficients are 0.3, 0.6 and 0.9, while scratching displacement amplitudes are 0.05 mm, 0.10 mm and 0.20 mm respectively. It is found that friction coefficient of 0.6 results in higher residual stress for both materials. Meanwhile, the predicted residual stress is proportional to the scratching displacement amplitude, higher displacement amplitude, resulting in higher residual stress. It is found that less residual stress is predicted on Super CMV material compared to Ti-6Al-4V material because of its high yield stress and ultimate strength. Super CMV material with friction coefficient of 0.3 and scratching displacement amplitude of 0.10 mm is recommended to be used in contact engineering applications due to its minimum possibility of fatigue.
Investigation of residual stress in laser welding dissimilar materials

International Nuclear Information System (INIS)

Mirim, Denilson de Camargo; Oliveira, Rene Ramos de; Berretta, Jose Roberto; Rossi, Wagner de; Lima, Nelson Batista de; Delijaicov, Sergio; Gomes, Diego Oliva

2010-01-01

One of the most critical problems found in the different materials welding is the residual stress formation, that happens mainly for the fact of those materials they possess coefficients of thermal expansion and different thermal conductivities. Like this in this work the residual tension was evaluated in the technique of welding laser among the steel low carbon, AISI 1010 and AISI 304. The materials were united for it welds autogenous of top with a laser of continuous Nd:YAG in that they were varied the potency, speed and the focus of the laser stayed constant in relation to surface of the sample. The main objective of the study went identification and to analysis of the residual stress in HAZ on both sides of seem. Um planning factorial of two factors at two levels each it was executed for optimization the combination of the factors potency and speed. The obtained answers were the residual stress in different depths in HAZ. In the surface of the sample measures of residual stress were accomplished by the technique of X-ray diffraction. The hole drilling strain gage method it was applied to measure the residual stress on both sides of the union. The results were analyzed using the variance analysis and the statistical regression based on the different influences of the entrance and combination of the factors in the residual stress generated in that union. The results indicate that the development of models can foresee the answers satisfactorily. (author)
Residual stress evaluation by neutron and synchrotron radiation

International Nuclear Information System (INIS)

Lodini, A.

2000-01-01

This lecture is dedicated to the residual stress evaluation using neutron and X ray synchrotron radiation. Residual stress evaluation is an important step for the improvement or the performance of materials, the control of the deformation of the components and the understanding of industrial process. In general, residual stress has various origins: mechanical, thermal, thermomechanical or thermochemical. In general, these residual stresses are caused by plastic deformation, or some source of local incompatibilities and are generated by three fundamental physical origins: plastic flow, volume change and thermal dilatation. These incompatibilities are compensated for partly by the elastic deformation that generates some internal stresses. In the solid, these local incompatibilities are caused by crystal defects. The exact origin of a stress is going to depend on the scale of observation. A classification of the residual stresses in three orders, related to the scale on which one considers materials, is proposed. The diffraction method for determination of macrostresses is based on the measurement of interplanar spacing for various direction in a diffraction experiment. Different examples are proposed. Polycrystalline grains or composite have different physical and elastic properties hence the stress for a particular grains or phase differs from the average value (value of macrostress). This difference is defined as the second order stress. The second order stresses occur because of small scale anisotropy or inhomogeneity in the material : for example, due to mismatch in coefficient of thermal expansion, elastic constants or plastic flow. However, the second order stress averaged over all grains or phase is not equal to zero and this average is called the mismatch stress. Using the experimental macro stress it is possible to calculate the mismatch stresses. More recently, this technique of diffraction has also been applied for the determination of microstrain (third
Improvement and Validation of Weld Residual Stress Modelling Procedure

International Nuclear Information System (INIS)

Zang, Weilin; Gunnars, Jens; Dong, Pingsha; Hong, Jeong K.

2009-06-01

The objective of this work is to identify and evaluate improvements for the residual stress modelling procedure currently used in Sweden. There is a growing demand to eliminate any unnecessary conservatism involved in residual stress assumptions. The study was focused on the development and validation of an improved weld residual stress modelling procedure, by taking advantage of the recent advances in residual stress modelling and stress measurement techniques. The major changes applied in the new weld residual stress modelling procedure are: - Improved procedure for heat source calibration based on use of analytical solutions. - Use of an isotropic hardening model where mixed hardening data is not available. - Use of an annealing model for improved simulation of strain relaxation in re-heated material. The new modelling procedure is demonstrated to capture the main characteristics of the through thickness stress distributions by validation to experimental measurements. Three austenitic stainless steel butt-welds cases are analysed, covering a large range of pipe geometries. From the cases it is evident that there can be large differences between the residual stresses predicted using the new procedure, and the earlier procedure or handbook recommendations. Previously recommended profiles could give misleading fracture assessment results. The stress profiles according to the new procedure agree well with the measured data. If data is available then a mixed hardening model should be used
Improvement and Validation of Weld Residual Stress Modelling Procedure

Energy Technology Data Exchange (ETDEWEB)

Zang, Weilin; Gunnars, Jens (Inspecta Technology AB, Stockholm (Sweden)); Dong, Pingsha; Hong, Jeong K. (Center for Welded Structures Research, Battelle, Columbus, OH (United States))

2009-06-15

The objective of this work is to identify and evaluate improvements for the residual stress modelling procedure currently used in Sweden. There is a growing demand to eliminate any unnecessary conservatism involved in residual stress assumptions. The study was focused on the development and validation of an improved weld residual stress modelling procedure, by taking advantage of the recent advances in residual stress modelling and stress measurement techniques. The major changes applied in the new weld residual stress modelling procedure are: - Improved procedure for heat source calibration based on use of analytical solutions. - Use of an isotropic hardening model where mixed hardening data is not available. - Use of an annealing model for improved simulation of strain relaxation in re-heated material. The new modelling procedure is demonstrated to capture the main characteristics of the through thickness stress distributions by validation to experimental measurements. Three austenitic stainless steel butt-welds cases are analysed, covering a large range of pipe geometries. From the cases it is evident that there can be large differences between the residual stresses predicted using the new procedure, and the earlier procedure or handbook recommendations. Previously recommended profiles could give misleading fracture assessment results. The stress profiles according to the new procedure agree well with the measured data. If data is available then a mixed hardening model should be used
Finite Element Residual Stress Analysis of Planetary Gear Tooth

Directory of Open Access Journals (Sweden)

Jungang Wang

2013-01-01

Full Text Available A method to simulate residual stress field of planetary gear is proposed. In this method, the finite element model of planetary gear is established and divided to tooth zone and profile zone, whose different temperature field is set. The gear's residual stress simulation is realized by the thermal compression stress generated by the temperature difference. Based on the simulation, the finite element model of planetary gear train is established, the dynamic meshing process is simulated, and influence of residual stress on equivalent stress of addendum, pitch circle, and dedendum of internal and external meshing planetary gear tooth profile is analyzed, according to non-linear contact theory, thermodynamic theory, and finite element theory. The results show that the equivalent stresses of planetary gear at both meshing and nonmeshing surface are significantly and differently reduced by residual stress. The study benefits fatigue cracking analysis and dynamic optimization design of planetary gear train.
Residual stress analysis in BWR pressure vessel attachments

International Nuclear Information System (INIS)

Dexter, R.J.; Leung, C.P.; Pont, D.

1992-06-01

Residual stresses from welding processes can be the primary driving force for stress corrosion cracking (SCC) in BWR components. Thus, a better understanding of the causes and nature of these residual stresses can help assess and remedy SCC. Numerical welding simulation software, such as SYSWELD, and material property data have been used to quantify residual stresses for application to SCC assessments in BWR components. Furthermore, parametric studies using SYSWELD have revealed which variables significantly affect predicted residual stress. Overall, numerical modeling techniques can be used to evaluate residual stress for SCC assessments of BWR components and to identify and plan future SCC research
Welding residual stress improvement in internal components by water jet peening

International Nuclear Information System (INIS)

Enomoto, K.; Hirano, K.; Hayashi, M.; Hayashi, E.

1996-01-01

Cavitations are generated when highly pressurized water is jetted in water. Surface residual stress is improved remarkably due to the peening effect of extremely high pressure caused by the collapse of cavitation bubbles. This technique is called water jet peening (WJP). WJP is expected to be an effective maintenance technique for the prevention of stress corrosion cracking caused by residual stress in various components of power generating plants. Various kinds of specimens were water jet peened to evaluate the fundamental characteristics of WJP and to select the most appropriate conditions for the residual stress improvement. Test results showed that WJP markedly improved the tensile residual stress caused by welding and grinding to the high compressive residual stress and seems to prevent the stress corrosion cracking
Measurement of residual stresses using fracture mechanics weight functions

International Nuclear Information System (INIS)

Fan, Y.

2000-01-01

A residual stress measurement method has been developed to quantify through-the-thickness residual stresses. Accurate measurement of residual stresses is crucial for many engineering structures. Fabrication processes such as welding and machining generate residual stresses that are difficult to predict. Residual stresses affect the integrity of structures through promoting failures due to brittle fracture, fatigue, stress corrosion cracking, and wear. In this work, the weight function theory of fracture mechanics is used to measure residual stresses. The weight function theory is an important development in computational fracture mechanics. Stress intensity factors for arbitrary stress distribution on the crack faces can be accurately and efficiently computed for predicting crack growth. This paper demonstrates that the weight functions are equally useful in measuring residual stresses. In this method, an artificial crack is created by a thin cut in a structure containing residual stresses. The cut relieves the residual stresses normal to the crack-face and allows the relieved residual stresses to deform the structure. Strain gages placed adjacent to the cut measure the relieved strains corresponding to incrementally increasing depths of the cut. The weight functions of the cracked body relate the measured strains to the residual stresses normal to the cut within the structure. The procedure details, such as numerical integration of the singular functions in applying the weight function method, will be discussed
Measurement of residual stresses using fracture mechanics weight functions

International Nuclear Information System (INIS)

Fan, Y.

2001-01-01

A residual stress measurement method has been developed to quantify through-the-thickness residual stresses. Accurate measurement of residual stresses is crucial for many engineering structures. Fabrication processes such as welding and machining generate residual stresses that are difficult to predict. Residual stresses affect the integrity of structures through promoting failures due to brittle fracture, fatigue, stress corrosion cracking, and wear. In this work, the weight function theory of fracture mechanics is used to measure residual stresses. The weight function theory is an important development in computational fracture mechanics. Stress intensity factors for arbitrary stress distribution on the crack faces can be accurately and efficiently computed for predicting crack growth. This paper demonstrates that the weight functions are equally useful in measuring residual stresses. In this method, an artificial crack is created by a thin cut in a structure containing residual stresses. The cut relieves the residual stresses normal to the crack-face and allows the relieved residual stresses to deform the structure. Strain gages placed adjacent to the cut measure the relieved strains corresponding to incrementally increasing depths of the cut. The weight functions of the cracked body relate the measured strains to the residual stresses normal to the cut within the structure. The procedure details, such as numerical integration of the singular functions in applying the weight function method, will be discussed. (author)
On residual stresses and fatigue of laser hardened steels

International Nuclear Information System (INIS)

Lin, Ru.

1992-01-01

This thesis deals with studies on residual stresses and fatigue properties of laser-transformation hardened steels. Two types of specimens, cylinders and fatigue specimens were used in the studies. The cylinders, made of Swedish steels SS 2244 and SS 2258 which correspond to AISI 4140 and AISI 52100 respectively, were locally hardened by a single scan of laser beam in the longitudinal direction, with various laser parameters. Residual stress distributions across the hardened tracks were measured by means of X-ray diffraction. The origins of residual stresses were investigated and discussed. For the fatigue specimens, including smooth and notched types made of Swedish steels SS 2244, SS 2225 and SS 1572 (similar to AISI 4140, AISI 4130 and AISI 1035, respectively), laser hardening was carried out in the gauge section. The residual stress field induced by the hardening process and the fatigue properties by plane bending fatigue test were studied. In order to investigate the stability of the residual stress field, stress measurements were also made on specimens being loaded near the fatigue limits for over 10 7 cycles. Further the concept of local fatigue strength was employed to correlate quantitatively the effect of hardness and residual stress field on the fatigue limits. In addition a group of smooth specimens of SS 2244 was induction hardened and the hardening results were compared with the corresponding laser hardened ones in terms of residual stress and fatigue behaviour. It has been found that compressive stresses exist in the hardened zone of all the specimens studied. The laser hardening condition, the specimen and how the hardening is carried out can significantly affect the residual stress field. Laser hardening can greatly improve the fatigue properties by inducing a hardened and compressed surface layer. (112 refs.)(au)
On residual stresses and fatigue of laser hardened steels

Energy Technology Data Exchange (ETDEWEB)

Lin, Ru.

1992-01-01

This thesis deals with studies on residual stresses and fatigue properties of laser-transformation hardened steels. Two types of specimens, cylinders and fatigue specimens were used in the studies. The cylinders, made of Swedish steels SS 2244 and SS 2258 which correspond to AISI 4140 and AISI 52100 respectively, were locally hardened by a single scan of laser beam in the longitudinal direction, with various laser parameters. Residual stress distributions across the hardened tracks were measured by means of X-ray diffraction. The origins of residual stresses were investigated and discussed. For the fatigue specimens, including smooth and notched types made of Swedish steels SS 2244, SS 2225 and SS 1572 (similar to AISI 4140, AISI 4130 and AISI 1035, respectively), laser hardening was carried out in the gauge section. The residual stress field induced by the hardening process and the fatigue properties by plane bending fatigue test were studied. In order to investigate the stability of the residual stress field, stress measurements were also made on specimens being loaded near the fatigue limits for over 10[sup 7] cycles. Further the concept of local fatigue strength was employed to correlate quantitatively the effect of hardness and residual stress field on the fatigue limits. In addition a group of smooth specimens of SS 2244 was induction hardened and the hardening results were compared with the corresponding laser hardened ones in terms of residual stress and fatigue behaviour. It has been found that compressive stresses exist in the hardened zone of all the specimens studied. The laser hardening condition, the specimen and how the hardening is carried out can significantly affect the residual stress field. Laser hardening can greatly improve the fatigue properties by inducing a hardened and compressed surface layer. (112 refs.)(au).
Development of residual stress prediction model in pipe weldment

Energy Technology Data Exchange (ETDEWEB)

Eom, Yun Yong; Lim, Se Young; Choi, Kang Hyeuk; Cho, Young Sam; Lim, Jae Hyuk [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

2002-03-15

When Leak Before Break(LBB) concepts is applied to high energy piping of nuclear power plants, residual weld stresses is a important variable. The main purpose of his research is to develop the numerical model which can predict residual weld stresses. Firstly, basic theories were described which need to numerical analysis of welding parts. Before the analysis of pipe, welding of a flat plate was analyzed and compared. Appling the data of used pipes, thermal/mechanical analysis were accomplished and computed temperature gradient and residual stress distribution. For thermal analysis, proper heat flux was regarded as the heat source and convection/radiation heat transfer were considered at surfaces. The residual stresses were counted from the computed temperature gradient and they were compared and verified with a result of another research.
Residual stresses due to weld repairs, cladding and electron beam welds and effect of residual stresses on fracture behavior. Annual report, September 1, 1977--November 30, 1978

International Nuclear Information System (INIS)

Rybicki, E.F.

1978-11-01

The study is divided into three tasks. Task I is concerned with predicting and understanding the effects of residual stresses due to weld repairs of pressure vessels. Task II examines residual stresses due to an electron beam weld. Task III addresses the problem of residual stresses produced by weld cladding at a nozzle vessel intersection. The objective of Task I is to develop a computational model for predicting residual stress states due to a weld repair of pressure vessel and thereby gain an understanding of the mechanisms involved in the creation of the residual stresses. Experimental data from the Heavy Section Steel Technology (HSST) program at Oak Ridge National Laboratories (ORNL) is used to validate the computational model. In Task II, the residual stress model is applied to the case of an electron beam weld of a compact tension freacture specimen. The results in the form of residual stresses near the weld are then used to explain unexpected fracture behavior which is observed in the testing of the specimen. For Task III, the residual stress model is applied to the cladding process used in nozzle regions of nuclear pressure vessels. The residual stresses obtained from this analysis are evaluated to determine their effect on the phenomena of under-clad cracking
Determination of residual stresses in roll compacted titanium strips

CSIR Research Space (South Africa)

Mothosi, KL

2017-01-01

Full Text Available residual stresses using x-ray diffraction (XRD) surface probing technique. Preliminary results were obtained for the surface residual stress at the center of the titanium strips for the 100 and 325 mesh strips rolled at 0.1 roll gap for 20 and 50 mm set...
Verification and Validation of Residual Stresses in Bi-Material Composite Rings

Energy Technology Data Exchange (ETDEWEB)

Nelson, Stacy Michelle [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Hanson, Alexander Anthony [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Briggs, Timothy [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Werner, Brian T. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

2017-07-01

Process-induced residual stresses commonly occur in composite structures composed of dissimilar materials. These residual stresses form due to differences in the composite materials’ coefficients of thermal expansion and the shrinkage upon cure exhibited by polymer matrix materials. Depending upon the specific geometric details of the composite structure and the materials’ curing parameters, it is possible that these residual stresses could result in interlaminar delamination or fracture within the composite. Therefore, the consideration of potential residual stresses is important when designing composite parts and their manufacturing processes. However, the experimental determination of residual stresses in prototype parts can be time and cost prohibitive. As an alternative to physical measurement, it is possible for computational tools to be used to quantify potential residual stresses in composite prototype parts. Therefore, the objectives of the presented work are to demonstrate a simplistic method for simulating residual stresses in composite parts, as well as the potential value of sensitivity and uncertainty quantification techniques during analyses for which material property parameters are unknown. Specifically, a simplified residual stress modeling approach, which accounts for coefficient of thermal expansion mismatch and polymer shrinkage, is implemented within the Sandia National Laboratories’ developed SIERRA/SolidMechanics code. Concurrent with the model development, two simple, bi-material structures composed of a carbon fiber/epoxy composite and aluminum, a flat plate and a cylinder, are fabricated and the residual stresses are quantified through the measurement of deformation. Then, in the process of validating the developed modeling approach with the experimental residual stress data, manufacturing process simulations of the two simple structures are developed and undergo a formal verification and validation process, including a mesh
Finite element analysis of residual stress in plasma-sprayed ceramic

International Nuclear Information System (INIS)

Mullen, R.L.; Hendricks, R.C.; McDonald, G.

1985-01-01

Residual stress in a ZrO 2 -Y 2 O 3 ceramic coating resulting from the plasma spraying operation is calculated. The calculations were done using the finite element method. Both thermal and mechanical analysis were performed. The resulting residual stress field was compared to the measurements obtained by Hendricks and McDonald. Reasonable agreement between the predicted and measured moment occurred. However, the resulting stress field is not in pure bending
Residual stress measurement with focused acoustic waves and direct comparison with X-ray diffraction stress measurements

International Nuclear Information System (INIS)

Sathish, Shamachary; Moran, Thomas J.; Martin, Richard W.; Reibel, Richard

2005-01-01

The technique of measuring small changes in acoustic wave velocity due to external or internal stress has been used for quantitative determination of residual stress in materials during the last decade. Application of similar methodology with focused acoustic waves leads to residual stress measurement with spatial resolution of a few millimeters to a few microns. The high spatial resolution residual stress measurement required development of new methodologies in both the design of acoustic lenses and the instrumentation for acoustic wave velocity determination. This paper presents two new methodologies developed for the measurement of residual stress with spatial resolution of a few millimeters. The design of new type of acoustic lens for achieving higher spatial resolution in residual stress measurement is introduced. Development of instrumentation for high precision local surface wave velocity measurement will be presented. Residual stresses measured around a crack tip in a sample of Ti-6A1-4V using a focused beam will be compared with X-ray diffraction measurements performed on the same region of the sample. Results of residual stress measurements along a direction perpendicular to the electron beam weld in a sample of Ti-6A1-4V, determined using focused acoustic waves and X-ray diffraction technique, are also presented. The spatial resolution and penetration depth of X-rays and focused acoustic beams with reference to residual stress measurements are discussed

The effect of initial stress induced during the steel manufacturing process on the welding residual stress in multi-pass butt welding

Directory of Open Access Journals (Sweden)

Jeong-ung Park

2018-03-01

Full Text Available A residual stress generated in the steel structure is broadly categorized into initial residual stress during manufacturing steel material, welding residual stress caused by welding, and heat treatment residual stress by heat treatment. Initial residual stresses induced during the manufacturing process is combined with welding residual stress or heat treatment residual stress, and remained as a final residual stress. Because such final residual stress affects the safety and strength of the structure, it is of utmost importance to measure or predict the magnitude of residual stress, and to apply this point on the design of the structure. In this study, the initial residual stress of steel structures having thicknesses of 25 mm and 70 mm during manufacturing was measured in order to investigate initial residual stress (hereinafter, referred to as initial stress. In addition, thermal elastic plastic FEM analysis was performed with this initial condition, and the effect of initial stress on the welding residual stress was investigated. Further, the reliability of the FE analysis result, considering the initial stress and welding residual stress for the steel structures having two thicknesses, was validated by comparing it with the measured results. In the vicinity of the weld joint, the initial stress is released and finally controlled by the weld residual stress. On the other hand, the farther away from the weld joint, the greater the influence of the initial stress. The range in which the initial stress affects the weld residual stress was not changed by the initial stress. However, in the region where the initial stress occurs in the compressive stress, the magnitude of the weld residual compressive stress varies with the compression or tension of the initial stress. The effect of initial stress on the maximum compression residual stress was far larger when initial stress was considered in case of a thickness of 25 mm with a value of 180�
Residual stress analysis in thick uranium films

International Nuclear Information System (INIS)

Hodge, A.M.; Foreman, R.J.; Gallegos, G.F.

2005-01-01

Residual stress analysis was performed on thick, 1-25 μm, depleted uranium (DU) films deposited on an Al substrate by magnetron sputtering. Two distinct characterization techniques were used to measure substrate curvature before and after deposition. Stress evaluation was performed using the Benabdi/Roche equation, which is based on beam theory of a bi-layer material. The residual stress evolution was studied as a function of coating thickness and applied negative bias voltage (0, -200, -300 V). The stresses developed were always compressive; however, increasing the coating thickness and applying a bias voltage presented a trend towards more tensile stresses and thus an overall reduction of residual stresses
Application of x-ray residual stress measurement to products

International Nuclear Information System (INIS)

Goto, T.; Iwamura, T.

1975-01-01

The X-ray residual stress measuring method is the only nondestructive method for measuring residual stress in polycrystalline materials. It is capable of obtaining information not only on macroscopic stress but also microscopic stress. The authors are employing this method for the development of pre-service and in-service inspection methods and for the improvement of various manufacturing techniques. In this paper, the results of measurement of some products as examples of its application are described. The examples introduced concern the following: (1) Selection of optimum conditions in heat treatment and stress-relief treatment. (2) Residual stress produced by mechanical processes such as autofrettage and flow form. (3) Check of manufacturing processes of rotary shaft and welded parts. (4) Estimation of fatigue strength of shot-peened part. (5) Detection of fatigue damage of shot-peened part. (auth.)
Residual stress state in an induction hardened steel bar determined by synchrotron- and neutron diffraction compared to results from lab-XRD

International Nuclear Information System (INIS)

Holmberg, Jonas; Steuwer, Axel; Stormvinter, Albin; Kristoffersen, Hans; Haakanen, Merja; Berglund, Johan

2016-01-01

Induction hardening is a relatively rapid heat treatment method to increase mechanical properties of steel components. However, results from FE-simulation of the induction hardening process show that a tensile stress peak will build up in the transition zone in order to balance the high compressive stresses close to the surface. This tensile stress peak is located in the transition zone between the hardened zone and the core material. The main objective with this investigation has been to non-destructively validate the residual stress state throughout an induction hardened component. Thereby, allowing to experimentally confirming the existence and magnitude of the tensile stress peak arising from rapid heat treatment. For this purpose a cylindrical steel bar of grade C45 was induction hardened and characterised regarding the microstructure, hardness, hardening depth and residual stresses. This investigation shows that a combined measurement with synchrotron/neutron diffraction is well suited to non-destructively measure the strains through the steel bar of a diameter of 20 mm and thereby making it possible to calculate the residual stress profile. The result verified the high compressive stresses at the surface which rapidly changes to tensile stresses in the transition zone resulting in a large tensile stress peak. Measured stresses by conventional lab-XRD showed however that at depths below 1.5 mm the stresses were lower compared to the synchrotron and neutron data. This is believed to be an effect of stress relaxation from the layer removal. The FE-simulation predicts the depth of the tensile stress peak well but exaggerates the magnitude compared to the measured results by synchrotron/neutron measurements. This is an important knowledge when designing the component and the heat treatment process since this tensile stress peak will have great impact on the mechanical properties of the final component.
Residual stress state in an induction hardened steel bar determined by synchrotron- and neutron diffraction compared to results from lab-XRD

Energy Technology Data Exchange (ETDEWEB)

Holmberg, Jonas, E-mail: jonas.holmberg@swerea.se [Swerea IVF AB, Argongatan 30, 431 22 Mölndal (Sweden); University West, 461 86 Trollhättan (Sweden); Steuwer, Axel [Nelson Mandela Metropolitan University, Gardham Avenue, 6031 Port Elizabeth (South Africa); Stormvinter, Albin; Kristoffersen, Hans [Swerea IVF AB, Argongatan 30, 431 22 Mölndal (Sweden); Haakanen, Merja [Stresstech OY, Tikkutehtaantie 1, 40 800 Vaajakoski (Finland); Berglund, Johan [Swerea IVF AB, Argongatan 30, 431 22 Mölndal (Sweden)

2016-06-14

Induction hardening is a relatively rapid heat treatment method to increase mechanical properties of steel components. However, results from FE-simulation of the induction hardening process show that a tensile stress peak will build up in the transition zone in order to balance the high compressive stresses close to the surface. This tensile stress peak is located in the transition zone between the hardened zone and the core material. The main objective with this investigation has been to non-destructively validate the residual stress state throughout an induction hardened component. Thereby, allowing to experimentally confirming the existence and magnitude of the tensile stress peak arising from rapid heat treatment. For this purpose a cylindrical steel bar of grade C45 was induction hardened and characterised regarding the microstructure, hardness, hardening depth and residual stresses. This investigation shows that a combined measurement with synchrotron/neutron diffraction is well suited to non-destructively measure the strains through the steel bar of a diameter of 20 mm and thereby making it possible to calculate the residual stress profile. The result verified the high compressive stresses at the surface which rapidly changes to tensile stresses in the transition zone resulting in a large tensile stress peak. Measured stresses by conventional lab-XRD showed however that at depths below 1.5 mm the stresses were lower compared to the synchrotron and neutron data. This is believed to be an effect of stress relaxation from the layer removal. The FE-simulation predicts the depth of the tensile stress peak well but exaggerates the magnitude compared to the measured results by synchrotron/neutron measurements. This is an important knowledge when designing the component and the heat treatment process since this tensile stress peak will have great impact on the mechanical properties of the final component.
Residual stress in spin-cast polyurethane thin films

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hong; Zhang, Li, E-mail: lizhang@mae.cuhk.edu.hk [Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin N.T., Hong Kong (China); Chow Yuk Ho Technology Centre for Innovative Medicine, The Chinese University of Hong Kong, Shatin N.T., Hong Kong (China)

2015-01-19

Residual stress is inevitable during spin-casting. Herein, we report a straightforward method to evaluate the residual stress in as-cast polyurethane thin films using area shrinkage measurement of films in floating state, which shows that the residual stress is independent of radial location on the substrate and decreased with decreasing film thickness below a critical value. We demonstrate that the residual stress is developed due to the solvent evaporation after vitrification during spin-casting and the polymer chains in thin films may undergo vitrification at an increased concentration. The buildup of residual stress in spin-cast polymer films provides an insight into the size effects on the nature of polymer thin films.
X-ray residual stress analysis on machined and tempered HPSN-ceramics

Energy Technology Data Exchange (ETDEWEB)

Immelmann, S.; Welle, E.; Reimers, W. [Hahn-Meitner-Institut Berlin GmbH (Germany)

1997-11-15

The residual stress state induced by grinding and tempering of hot pressed silicon nitride (HPSN) samples is studied by X-ray diffraction. The results reveal that the residual stress values at the surface of the samples as well as their gradient within the penetration depth of the X-rays depend on the sintering aid and thus, on the glassy phase content of the HPSN. Tempering of the ground HPSN reduces the residual stress values due to microplastic deformation, whereas an oxidation of the glassy phase leads to the formation of compressive residual stresses. (orig.) 35 refs.
Residual stress characterization of steel TIG welds by neutron diffraction and by residual magnetic stray field mappings

Energy Technology Data Exchange (ETDEWEB)

Stegemann, Robert, E-mail: Robert.Stegemann@bam.de [Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12200 Berlin (Germany); Cabeza, Sandra; Lyamkin, Viktor; Bruno, Giovanni; Pittner, Andreas [Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12200 Berlin (Germany); Wimpory, Robert; Boin, Mirko [HZB Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Kreutzbruck, Marc [Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12200 Berlin (Germany); IKT, University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart (Germany)

2017-03-15

The residual stress distribution of tungsten inert gas welded S235JRC+C plates was determined by means of neutron diffraction (ND). Large longitudinal residual stresses with maxima around 600 MPa were found. With these results as reference, the evaluation of residual stress with high spatial resolution GMR (giant magneto resistance) sensors was discussed. The experiments performed indicate a correlation between changes in residual stresses (ND) and the normal component of local residual magnetic stray fields (GMR). Spatial variations in the magnetic field strength perpendicular to the welds are in the order of the magnetic field of the earth. - Highlights: • Comparison of magnetic microstructure with neutron diffraction stress analysis. • High spatial resolution magnetic stray field images of hypereutectoid TIG welds. • Spatial variations of the stray fields are below the magnetic field of the earth. • GMR spin valve gradiometer arrays adapted for the evaluation of magnetic microstructures. • Magnetic stray fields are closely linked to microstructure of the material.
Residual stress in silicon wafer using IR polariscope

Science.gov (United States)

Lu, Zhijia; Wang, Pin; Asundi, Anand

2008-09-01

The infrared phase shift polariscope (IR-PSP) is a full-field optical technique for stress analysis in Silicon wafers. Phase shift polariscope is preferred to a conventional polariscope, as it can provide quantitative information of the normal stress difference and the shear stress in the specimen. The method is based on the principles of photoelasticity, in which stresses induces temporary birefringence in materials which can be quantitatively analyzed using a phase shift polariscope. Compared to other stress analysis techniques such as x-ray diffraction or laser scanning, infrared photoelastic stress analysis provides full-field information with high resolution and in near real time. As the semiconductor fabrication is advancing, larger wafers, thinner films and more compact packages are being manufactured. This results in a growing demand of process control. Residual stress exist in silicon during semiconductor fabrication and these stresses may make cell processing difficult or even cause the failure of the silicon. Reducing these stresses would improve manufacturability and reliability. Therefore stress analysis is essential to trace the root cause of the stresses. The polariscope images are processed using MATLAB and four-step phase shifting method to provide quantitative as well as qualitative information regarding the residual stress of the sample. The system is calibrated using four-point bend specimen and then the residual stress distribution in a MEMS sample is shown.
Evaluation of Residual Stresses using Ring Core Method

Directory of Open Access Journals (Sweden)

Holý S.

2010-06-01

Full Text Available The method for measuring residual stresses using ring-core method is described. Basic relations are given for residual stress measurement along the specimen depth and simplified method is described for average residual stress estimation in the drilled layer for known principal stress directions. The estimation of calculated coefficients using FEM is described. Comparison of method sensitivity is made with hole-drilling method. The device for method application is described and an example of experiment is introduced. The accuracy of method is discussed. The influence of strain gauge rosette misalignment to the evaluated residual stresses is performed using FEM.
Benchmark on residual stress modeling in fracture mechanics assessment

International Nuclear Information System (INIS)

Marie, S.; Deschanels, H.; Chapuliot, S.; Le Delliou, P.

2014-01-01

In the frame of development in analytical defect assessment methods for the RSE-M and RCC-MRx codes, new work on the consideration of residual stresses is initiated by AREVA, CEA and EDF. The first step of this work is the realization of a database of F.E. reference cases. To validate assumptions and develop a good practice guideline for the consideration of residual stresses in finite element calculations, a benchmark between AREVA, CEA and EDF is going-on. A first application presented in this paper focuses on the analysis of the crack initiation of aged duplex stainless steel pipes submitted to an increasing pressure loading. Residual stresses are related to pipe fabrication process and act as shell bending condition. Two tests were performed: the first with an internal longitudinal semi-elliptical crack and the second with an external crack. The analysis first focuses on the ability to accurately estimate the measured pressure at the crack initiation of the two tests. For that purpose, the comparison of results obtained with different methods of taking into account the residual stresses (i.e. thermal fields or initial strain field). It then validates post-treatment procedures for J or G determination, and finally compares of the results obtained by the different partners. It is then shown that the numerical models can integrate properly the impact of residual stresses on the crack initiation pressure. Then, an excellent agreement is obtained between the different numerical evaluations of G provided by the participants to the benchmark so that best practice and reference F.E. solutions for residual stresses consideration can be provided based on that work. (authors)
Residual stresses in weld-clad reactor pressure vessel steel

International Nuclear Information System (INIS)

Bertram, W.

1975-01-01

Cladding of low alloy nuclear reactor pressure vessel steel with austenitic stainless steel introduces in heavy section components high residual stresses which may cause microcrack formation in stress relief heat treatment. In this investigation an attempt is made to contribute to the solution of the stress relief cracking problem by determining quantitatively the magnitude and distribution of the residual stresses after cladding and after subsequent stress relief heat treatment. The distribution of residual stresses was determined on the basis of a combined experimental-mathematical procedure. Heavy section plate specimens of low alloy steel as base material were given an austenitic monolayer-cladding using the techniques of strip electrode and plasma hot wire cladding, respectively. A number of plates was stress relief heat treated. Starting from the cladded surface the thickness of the plates was reduced by subsequent removal of layers of material. The elastic strain reaction to the removal of each layer was measured by strain gauges. From the data obtained the biaxial residual stress distribution was computed as a function of thickness using relations which are derived for this particular case. In summary, lower residual stresses are caused by reduced thickness of the components. As the heat input, is decreased at identical base material thickness, the residual stresses are lowered also. The height of the tensile residual stress peak, however, remains approximataly constant. In stress relief annealed condition the residual stresses in the cladding are in tension; in the base material the residual stresses are negligibly small
Residual stresses analysis of friction stir welding using one-way FSI simulation

International Nuclear Information System (INIS)

Kang, Sung Wook; Jang, Beom Seon; Song, Ha Cheol

2015-01-01

When certain mechanisms, such as plastic deformations and temperature gradients, occur and are released in a structure, stresses remain because of the shape of the structure and external constraints. These stresses are referred to as residual stresses. The base material locally expands during heating in the welding process. When the welding is completed and cooled to room temperature, the residual stresses are left at nearly the yield strength level. In the case of friction stir welding, the maximum temperature is 80% to 90% of the melting point of the materials. Thus, the residual stresses in the welding process are smaller than those in other fusion welding processes; these stresses have not been considered previously. However, friction stir welding residual stresses are sometimes measured at approximately 70% or above. These residual stresses significantly affect fatigue behavior and lifetime. The present study investigates the residual stress distributions in various welding conditions and shapes of friction stir welding. In addition, the asymmetric feature is considered in temperature and residual stress distribution. Heat transfer analysis is conducted using the commercial computational fluid dynamics program Fluent, and results are used in the finite element structural analysis with the ANSYS Multiphysics software. The calculated residual stresses are compared with experimental values using the X-ray diffraction method.
Modeling of CMUTs with Multiple Anisotropic Layers and Residual Stress

DEFF Research Database (Denmark)

Engholm, Mathias; Thomsen, Erik Vilain

2014-01-01

Usually the analytical approach for modeling CMUTs uses the single layer plate equation to obtain the deflection and does not take anisotropy and residual stress into account. A highly accurate model is developed for analytical characterization of CMUTs taking an arbitrary number of layers...... and residual stress into account. Based on the stress-strain relation of each layer and balancing stress resultants and bending moments, a general multilayered anisotropic plate equation is developed for plates with an arbitrary number of layers. The exact deflection profile is calculated for a circular...... clamped plate of anisotropic materials with residual bi-axial stress. From the deflection shape the critical stress for buckling is calculated and by using the Rayleigh-Ritz method the natural frequency is estimated....
Residual Stress Studies Using the Cairo Fourier Diffractometer Facility

International Nuclear Information System (INIS)

Maayouf, R.M.A.; El-Shaer, Y.H.

2002-01-01

The present paper deals with residual stress studies using the Cairo Fourier diffractometer facility CFDF. The CFDF is a reverse - time of -flight (RTOF) diffractometer; applies a Fourier chopper. The measurements were performed for copper samples in order to study the residual stress after welding. The maximum modulation of the Fourier chopper during the measurements was 136 khz; leading to a time resolution half-width of about 7 μ s. It has been found from the present measurements that, the resulting diffraction spectra could be successfully used for studying the residual stress; in the wavelength range between 0.7-2.9 A degree at ∼ 0.45 % relative resolution
Residual stress determination of rail tread using a laser ultrasonic technique

International Nuclear Information System (INIS)

Wang, Jing; Feng, Qibo

2015-01-01

A non-destructive method for measuring the residual stress on rail tread that uses a laser-generated ultrasonic technique is proposed. The residual stress distribution of different parts on both the new rail and used rail were examined. The surface acoustic waves (SAWs) are excited by a scanning line laser and detected by a laser ultrasonic detection system. A digital correlation method was used for calculating the changes in velocity of SAWs, which reflects the stress distribution. A wavelet de-noising technique and a least square fit were used for signal processing to improve the measurement accuracy. The effects of ultrasonic propagation distance and surface roughness on the determination of residual stress were analyzed and simulated. Results from the study demonstrate that the stress distribution results are accordant with the practical situation, and the laser-generated SAWs technique is a promising tool for the determination of residual stress in the railway inspection and other industrial testing fields. (paper)
Numerical simulation of transformation-induced microscopic residual stress in ferrite-martensite lamellar steel

International Nuclear Information System (INIS)

Mikami, Y; Inao, A; Mochizuki, M; Toyoda, M

2009-01-01

The effect of transformation-induced microscopic residual stress on fatigue crack propagation behavior of ferrite-martensite lamellar steel was discussed. Fatigue tests of prestrained and non-prestrained specimens were performed. Inflections and branches at ferrite-martensite boundaries were observed in the non-prestrained specimens. On the other hand, less inflections and branches were found in the prestrained specimens. The experimental results showed that the transformation induced microscopic residual stress has influence on the fatigue crack propagation behavior. To estimate the microscopic residual, a numerical simulation method for the calculation of microscopic residual stress stress induced by martensitic transformation was performed. The simulation showed that compressive residual stress was generated in martensite layer, and the result agree with the experimental result that inflections and branches were observed at ferrite-martensite boundaries.
The effect of Residual Stress on the Stress Intensity Factor of Nuclear Material

International Nuclear Information System (INIS)

Song, Taek Ho

2008-01-01

As NPP (Nuclear Power Plant) gets aged, the importance of the pressure boundary integrity increases very much to those who are trying to operate their plant beyond its design life. Not long ago, Boric acid crystal was found at the RPV outlet nozzle of V.C. Summer plant during the visual examination in 2000. After this finding, non-destructive examination was taken to find out what's taken place. As a result of this examination, circumferential and axial cracks were found. With Metallurgical structure examination, it was shown that crack had been developed at the mid-point between Inco-alloy buttering and weld metal. It was turned out that high welding residual stress was the main cause of the cracking. Because of the through wall crack, nozzle and welding parts were replaced. Many other nuclear power plants experienced similar pressure boundary stress corrosion cracks (SCCs). KEPRI (Korea Electric Power Research Institute) has carried out research projects for managing and preventing these kinds of cracks in nuclear power plants (NPPs). The titles of these research projects are 'Development of Stress Corrosion Cracking Management Technology and Aging Monitor for NPP Main Components' and 'Development of Analysis Technology for Crack Management of Dissimilar Metal Weld'. Through these projects, residual stress measurement techniques have been exercised at various points in mock-up test specimens to simulate nuclear power plant dissimilar base metal and weldment residual stress. X-ray test and hole drilling method have been reviewed to measure residual stresses of the dissimilar metal welds. This paper shows some point of view in residual stress measurement. Fracture mechanics analysis has been performed to explain the importance of residual stress measurement in association with nuclear power plant safety
On residual stress prescriptions for fitness for service assessment of pipe girth welds

International Nuclear Information System (INIS)

Dong, Pingsha; Song, Shaopin; Zhang, Jinmiao; Kim, Myung H.

2014-01-01

This paper aims to provide a detailed assessment of some of the existing residual stress profiles stipulated in widely used fitness-for-service assessment codes and standards, such as BS 7910 Appendix Q and API 579 RP Annex E, by taking advantage of some comprehensive residual stress studies that have recently become available. After presenting a case study on which residual stress measurements are available for validating finite element based residual stress analysis procedure, residual stress profiles stipulated in BS 7910 for pipe girth welds are selected for detailed evaluation by comparing residual stress distribution characteristics shown in parametric finite element results. A shell theory based full-field residual stress profile estimation scheme is then presented to illustrate how an improved estimation of residual stress profiles can be achieved in light of some of the deficiencies in BS 7910 and API 579 identified in this study. - Highlights: • Critically assessed girth weld residual stress profiles in major FFS Codes and Standards. • Identified deficiencies in relating to pipe geometry, heat input, and axial distance from weld. • Presented a shell theory based scheme for prescribing full-field residual stress profiles
Effects of shot peening on the residual stress of welded SS400 steel

International Nuclear Information System (INIS)

Lee, Jong Man; Kim, Tae Hyung; Cheong, Seong Kyun; Lee, Seung Ho

2002-01-01

The fatigue life of structures is usually determined by welding zone. The tensile residual stress, which is induced by welding, reduces the fatigue life and fatigue strength of welded structures. If we remove the tensile residual stress or induce the compressive residual stress, the fatigue life of welded structures will be improved. The change of hardness and compressive residual stress of welded zone after shot peening was investigated in this paper. The results show that the hardness was increased by shot peening. The residual stress was reduced by shot peening

Convenient measurement of the residual stress using X-ray penetration depth

International Nuclear Information System (INIS)

Ukai, Takayoshi; Shibano, Junichi

1994-01-01

The residual stress measured with a characteristic X-ray is usually evaluated as a surface stress. However, it is a weighted mean value over all penetration depth of X-ray. Thus, the classical sin 2 Ψ method with the characteristic X-ray is difficult to use for measuring the steep gradient of residual stress that occurs along the depth direction in a subsurface layer of the material after cold rolling and grinding. This paper presents a convenient method of the residual stress measurement along the depth direction in a subsurface layer using the penetration depth depending on a characteristic X-ray. The residual stress distribution of JIS SKS51 steel plate was measured as an example of applying this method. As a result, it could be confirmed that a residual stress distribution along the depth direction in a subsurface layer could be evaluated nondestructively by this convenient method. (author)
Effect of residual stress on the nanoindentation response of (100) copper single crystal

International Nuclear Information System (INIS)

Zhu, Li-na; Xu, Bin-shi; Wang, Hai-dou; Wang, Cheng-biao

2012-01-01

Experimental measurements were used to investigate the effect of residual stress on the nanoindentation of (100) copper single crystal. Equi-biaxial tensile and compressive stresses were applied to the copper single crystal using a special designed apparatus. It was found that residual stresses greatly affected peak load, curvature of the loading curve, elastically recovered depth, residual depth, indentation work, pile-up amount and contact area. The Suresh and Giannakopoulos and Lee and Kwon methods were used to calculate the residual stresses from load-depth data and morphology observation of nanoindents using atomic force microscopy. Comparison of the obtained results with stress values from strain gage showed that the residual stresses analyzed from the Suresh and Giannakopoulos model agreed well with the applied stresses. -- Highlights: ► Residual stresses greatly affected various nanoindentation parameters. ► The contact area can be accurately measured from AFM observation. ► The residual stresses analyzed from the S and G model agreed well with applied stresses.
Residual Stress Evaluation of Weld Inlay Process on Reactor Vessel Nozzles

Energy Technology Data Exchange (ETDEWEB)

Cho, Kihyun; Cho, Hong Seok [KEPCO KPS, Naju (Korea, Republic of)

2015-10-15

Weld overlay, weld inlay and stress improvement are mitigation technologies for butt joints. Weld overlay is done on pressurizer nozzles which are the highest potential locations occurring PWSCC due to high temperature in Korea. Reactor vessel nozzles are other big safety concerns for butt joints. Weld overlay and stress improvement should be so difficult to apply to those locations because space is too limited. Weld inlay should be one of the solutions. KEPCO KPS has developed laser welding system and process for reactor nozzles. Welding residual stress analysis is necessary for flaw evaluation. United States nuclear regulatory commission has calculated GTAW(Gas Tungsten Arc Welding) residual stress using ABAQUS. To confirm effectiveness of weld inlay process, welding residual stress analysis was performed. and difference between GTAW and LASER welding process was compared. Evaluation of weld inlay process using ANSYS and ABAQUS is performed. All of the both results are similar. The residual stress generated after weld inlay was on range of 450-500 MPa. Welding residual stresses are differently generated by GTAW and LASER welding. But regardless of welding process type, residual tensile stress is generated on inside surface.
Numerical and Experimental Study on the Residual Stresses in the Nitrided Steel

Science.gov (United States)

Song, X.; Zhang, Zhi-Qian; Narayanaswamy, S.; Huang, Y. Z.; Zarinejad, M.

2016-09-01

In the present work, residual stresses distribution in the gas nitrided AISI 4140 sample has been studied using finite element (FE) simulation. The nitrogen concentration profile is obtained from the diffusion-controlled compound layer growth model, and nitrogen concentration controls the material volume change through phase transformation and lattice interstitials which results in residual stresses. Such model is validated through residual stress measurement technique—micro-ring-core method, which is applied to the nitriding process to obtain the residual stresses profiles in both the compound and diffusion layer. The numerical and experimental results are in good agreement with each other; they both indicate significant stress variation in the compound layer, which was not captured in previous research works due to the resolution limit of the traditional methods.
An analytical method on the surface residual stress for the cutting tool orientation

Science.gov (United States)

Li, Yueen; Zhao, Jun; Wang, Wei

2010-03-01

The residual stress is measured by choosing 8 kinds orientations on cutting the H13 dies steel on the HSM in the experiment of this paper. The measured data shows on that the residual stress exists periodicity for the different rake angle (β) and side rake angle (θ) parameters, further study find that the cutting tool orientations have closed relationship with the residual stresses, and for the original of the machined residual stress on the surface from the cutting force and the axial force, it can be gained the simply model of tool-workpiece force, using the model it can be deduced the residual stress model, which is feasible to calculate the size of residual stress. And for almost all the measured residual stresses are compressed stress, the compressed stress size and the direction could be confirmed by the input data for the H13 on HSM. As the result, the residual stress model is the key for optimization of rake angle (β) and side rake angle (θ) in theory, using the theory the more cutting mechanism can be expressed.
The influence of texture on residual stress measurements

International Nuclear Information System (INIS)

Lima, N.B. de.

1991-01-01

A computer program to calculate the orientation distribution function (ODF) from incomplete pole figures has been developed for rolled materials with a cubic structure. This program is based on Bunge's series expansion. The use of incomplete pole figures results in the loss of orthogonality among symmetric spherical harmonic functions and makes it necessary to explicitly evaluate the integrals. The ODF has been used to quantitatively evaluate the influence of texture in determining residual stresses. This has been done by calculating theoretically the strain undergone by each cell as a function of its orientation to residual stress relationship. To test the ODF program, cold rolled Cu and Al specimens were used and to evaluate residual stresses as a function of texture, cold rolled AISI 430 and 324 specimens were used. Simulations have also be presented based on the texture for each of the materials, to verify the nature of the curve d x sin 2 ψ as a function of each stress tensor components. (author)
Experimental Investigation of Principal Residual Stress and Fatigue Performance for Turned Nickel-Based Superalloy Inconel 718.

Science.gov (United States)

Hua, Yang; Liu, Zhanqiang

2018-05-24

Residual stresses of turned Inconel 718 surface along its axial and circumferential directions affect the fatigue performance of machined components. However, it has not been clear that the axial and circumferential directions are the principle residual stress direction. The direction of the maximum principal residual stress is crucial for the machined component service life. The present work aims to focuses on determining the direction and magnitude of principal residual stress and investigating its influence on fatigue performance of turned Inconel 718. The turning experimental results show that the principal residual stress magnitude is much higher than surface residual stress. In addition, both the principal residual stress and surface residual stress increase significantly as the feed rate increases. The fatigue test results show that the direction of the maximum principal residual stress increased by 7.4%, while the fatigue life decreased by 39.4%. The maximum principal residual stress magnitude diminished by 17.9%, whereas the fatigue life increased by 83.6%. The maximum principal residual stress has a preponderant influence on fatigue performance as compared to the surface residual stress. The maximum principal residual stress can be considered as a prime indicator for evaluation of the residual stress influence on fatigue performance of turned Inconel 718.
Experimental Investigation of Principal Residual Stress and Fatigue Performance for Turned Nickel-Based Superalloy Inconel 718

Directory of Open Access Journals (Sweden)

Yang Hua

2018-05-01

Full Text Available Residual stresses of turned Inconel 718 surface along its axial and circumferential directions affect the fatigue performance of machined components. However, it has not been clear that the axial and circumferential directions are the principle residual stress direction. The direction of the maximum principal residual stress is crucial for the machined component service life. The present work aims to focuses on determining the direction and magnitude of principal residual stress and investigating its influence on fatigue performance of turned Inconel 718. The turning experimental results show that the principal residual stress magnitude is much higher than surface residual stress. In addition, both the principal residual stress and surface residual stress increase significantly as the feed rate increases. The fatigue test results show that the direction of the maximum principal residual stress increased by 7.4%, while the fatigue life decreased by 39.4%. The maximum principal residual stress magnitude diminished by 17.9%, whereas the fatigue life increased by 83.6%. The maximum principal residual stress has a preponderant influence on fatigue performance as compared to the surface residual stress. The maximum principal residual stress can be considered as a prime indicator for evaluation of the residual stress influence on fatigue performance of turned Inconel 718.
Residual-stress distributions near stainless steel butt weldments

International Nuclear Information System (INIS)

Elligson, W.A.; Shack, W.J.

1978-01-01

Concern for the integrity of stainless steel butt-weldments in boiling-water-reactor (BWR) piping systems has stimulated study of the conditions that cause stress corrosion cracking (SCC) in the heat-affected zones (HAZ) of the weldments. It is generally agreed that a high stress exceeding the initial yield strength is one of the essential elements for crack initiation. Since design procedures usually ensure that load stresses are below initial yield, the source of the high stresses necessary to produce SCC is thought to be the residual stresses due to welding. To examine the level of residual stresses in the weldments of interest, bulk residual stresses were measured on 100 mm (4-in.) and 254 mm (10-in.) diameter Schedule 80 piping weldments using strain relief techniques. Both laboratory welded specimens and field welded specimens from reactors in service were studied. Axial bulk residual stress distributions were obtained at 45 0 intervals around the circumference. At each azimuthal position, the residual stresses were measured at seven axial positions: on the weld centerline and 13, 20, and 25 mm on either side of the weld centerline on both the inside and outside surfaces
The interaction of fatigue cracks with a residual stress field using thermoelastic stress analysis and synchrotron X-ray diffraction experiments

Science.gov (United States)

Amjad, Khurram; Asquith, David; Sebastian, Christopher M.; Wang, Wei-Chung

2017-01-01

This article presents an experimental study on the fatigue behaviour of cracks emanating from cold-expanded holes utilizing thermoelastic stress analysis (TSA) and synchrotron X-ray diffraction (SXRD) techniques with the aim of resolving the long-standing ambiguity in the literature regarding potential relaxation, or modification, of beneficial compressive residual stresses as a result of fatigue crack propagation. The crack growth rates are found to be substantially lower as the crack tip moved through the residual stress zone induced by cold expansion. The TSA results demonstrated that the crack tip plastic zones were reduced in size by the presence of the residual compressive stresses induced by cold expansion. The crack tip plastic zones were found to be insignificant in size in comparison to the residual stress zone resulting from cold expansion, which implied that they were unlikely to have had a notable impact on the surrounding residual stresses induced by cold expansion. The residual stress distributions measured along the direction of crack growth, using SXRD, showed no signs of any significant stress relaxation or redistribution, which validates the conclusions drawn from the TSA data. Fractographic analysis qualitatively confirmed the influence on crack initiation of the residual stresses induced by the cold expansion. It was found that the application of single compressive overload caused a relaxation, or reduction in the residual stresses, which has wider implications for improving the fatigue life. PMID:29291095
Recent advances in residual stress measurement

International Nuclear Information System (INIS)

Withers, P.J.; Turski, M.; Edwards, L.; Bouchard, P.J.; Buttle, D.J.

2008-01-01

Until recently residual stresses have been included in structural integrity assessments of nuclear pressure vessels and piping in a very primitive manner due to the lack of reliable residual stress measurement or prediction tools. This situation is changing the capabilities of newly emerging destructive (i.e. the contour method) and non-destructive (i.e. magnetic and high-energy synchrotron X-ray strain mapping) residual stress measurement techniques for evaluating ferritic and austenitic pressure vessel components are contrasted against more well-established methods. These new approaches offer the potential for obtaining area maps of residual stress or strain in welded plants, mock-up components or generic test-pieces. The mapped field may be used directly in structural integrity calculations, or indirectly to validate finite element process/structural models on which safety cases for pressurised nuclear systems are founded. These measurement methods are complementary in terms of application to actual plant, cost effectiveness and measurements in thick sections. In each case an exemplar case study is used to illustrate the method and to highlight its particular capabilities
Relation Between Residual and Hoop Stresses and Rolling Bearing Fatigue Life

Science.gov (United States)

Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

2015-01-01

Rolling-element bearings operated at high speed or high vibration may require a tight interference fit between the bore of the bearing and shaft to prevent rotation of the bearing bore around the shaft and fretting damage at the interfaces. Previous work showed that the hoop stresses resulting from tight interference fits can reduce bearing lives by as much as 65 percent. Where tight interference fits are required, case-carburized steel such as AISI 9310 or M50 NiL is often used because the compressive residual stresses inhibit subsurface crack formation and the ductile core inhibits inner-ring fracture. The presence of compressive residual stress and its combination with hoop stress also modifies the Hertz stress-life relation. This paper analyzes the beneficial effect of residual stresses on rolling-element bearing fatigue life in the presence of high hoop stresses for three bearing steels. These additional stresses were superimposed on Hertzian principal stresses to calculate the inner-race maximum shearing stress and the resulting fatigue life of the bearing. The load-life exponent p and Hertz stress-life exponent n increase in the presence of compressive residual stress, which yields increased life, particularly at lower stress levels. The Zaretsky life equation is described and is shown to predict longer bearing lives and greater load- and stress-life exponents, which better predicts observed life of bearings made from vacuum-processed steel.
Measurement of residual stresses in welded sample of dissimilar materials

International Nuclear Information System (INIS)

Mansur, Tanius Rodrigues; Gomes, Paulo de Tarso Vida; Scaldaferri, Denis Henrique Bianchi; Martins, Geraldo Antonio Scoralick; Atanazio Filho, Nelson do Nascimento

2008-01-01

The welding of dissimilar metals has several applications in the industry. Especially in the nuclear industry, this joint type, common between carbon steel and stainless steel, it is always reason of analysis and special cares tends in view the need to maintain the integrity of the equipment. Residual stresses are introduced in the material as a result of processes as welding, machining, sanding and polishing that can to produce deformation in the proximities of the surface of the material. Residual compressive stresses can be introduced in the material through the jetting process (bombardment of the surface for small glass spheres, dry sand or steel). That procedure allows a fine subsurface layer to suffer yielding, compressing the superficial layer and reducing the formation of areas of concentration of traction stresses, increasing the resistance of the material to the fatigue. The welding process introduces residual stresses due to the geometry resulting from the fusion of the material welded and of the heterogeneous cooling. Besides the microstructural alteration and chemical composition of the material in the affected area for the heat, introduced by the welding, it is also had the effect of the discontinuity of the passes and the formation of bubbles and emptiness that can contribute to the cracks nucleation, reducing the resistance to the fatigue. In the great majority of the times residual stresses are harmful and there are many documented cases which US these stresses went predominant factors for the failure for fatigue. A particularly dangerous aspect of the residual stresses is that their presence is not usually observed, what usually happens with an applied load to the structure. The knowledge of the surface residual stresses is important to predict the emergence of failure when the component or structure is requested. In nuclear power plants it is common to welding of piping of stainless steels with mouthpieces of carbon steel of pressure vases of
Residual stresses generated in F-522 steel by different machining processes

International Nuclear Information System (INIS)

Gracia-Navas, V.; Ferreres, I.; Maranon, J. A.; Garcia-Rosales, C.; Gil-Sevillano, J.

2005-01-01

Machining operations induce plastic deformation and heat generation in the near surface area of the machined part, giving rise to residual stresses. Depending on their magnitude and sign, these stresses can be detrimental or beneficial to the service life of the part. The final stress state depends on the machining process applied, as well as on the machining parameters. Therefore, the establishment of adequate machining guidelines requires the measurement of the residual stresses generated both at the surface and inside the material. in this work, the residual stresses generated in F-522 steel by two hard turning (conventional and laser assisted) and two grinding (production and finishing) processes were measured by X-ray diffraction. Additionally, depth profiles of the volume fraction of retained austenite, microstructure and nano hardness were obtained in order to correlate those results with the residual stress state obtained for each machining process. It has been observed that turning generates tensile stresses in the surface while grinding causes compressive stresses. Below the surface grinding generates weak tensile or nearly null stresses whereas turning generates strong compressive stresses. These results show that the optimum mechanising process (disregarding economical considerations) implies the combination of turning plus elimination of a small thickness by final grinding. (Author) 19 refs
Mapping residual stress by ultrasonic tomography

International Nuclear Information System (INIS)

Hildebrand, B.P.; Harrington, T.P.

1979-01-01

It is known that internal stress concentrations can give rise to microcracks which then grow when the structure is subjected to external forces. It has also been found that the velocity of sound is altered as it propagates through a region of stress. In this paper a technique called Computer-Assisted Tomography (CAT) is discussed and an application that provides pictures of stress fields is described. The results of both simulated and experimental models used to evaluate the technique are reported. It is concluded that the CAT approach has great potential for locating and mapping residual stress in metals. (author)
Minimization of Residual Stress in an Al-Cu Alloy Forged Plate by Different Heat Treatments

Science.gov (United States)

Dong, Ya-Bo; Shao, Wen-Zhu; Jiang, Jian-Tang; Zhang, Bao-You; Zhen, Liang

2015-06-01

In order to improve the balance of mechanical properties and residual stress, various quenching and aging treatments were applied to Al-Cu alloy forged plate. Residual stresses determined by the x-ray diffraction method and slitting method were compared. The surface residual stress measured by x-ray diffraction method was consistent with that measured by slitting method. The residual stress distribution of samples quenched in water with different temperatures (20, 60, 80, and 100 °C) was measured, and the results showed that the boiling water quenching results in a 91.4% reduction in residual stress magnitudes compared with cold water quenching (20 °C), but the tensile properties of samples quenched in boiling water were unacceptably low. Quenching in 80 °C water results in 75% reduction of residual stress, and the reduction of yield strength is 12.7%. The residual stress and yield strength level are considerable for the dimensional stability of aluminum alloy. Quenching samples into 30% polyalkylene glycol quenchants produced 52.2% reduction in the maximum compressive residual stress, and the reduction in yield strength is 19.7%. Moreover, the effects of uphill quenching and thermal-cold cycling on the residual stress were also investigated. Uphill quenching and thermal-cold cycling produced approximately 25-40% reduction in residual stress, while the effect on tensile properties is quite slight.
Residual stresses in a co-sintered SOC half-cell during post-sintering cooling

DEFF Research Database (Denmark)

Charlas, Benoit; Chatzichristodoulou, Christodoulos; Brodersen, Karen

2014-01-01

.e. the reference temperature (Tref) or the strain difference based on the curvature. This approximation gives good results for bilayers with a defined cooling temperature profile, where the curvature of the bilayer defines a unique balance between the two unknown residual stress states in the two layers......Due to the thermal expansion mismatch between the layers of a Solid Oxide Cell, residual stresses (thermal stresses) develop during the cooling after sintering. Residual stresses can induce cell curvature for asymmetric cells but more importantly they also result in more fragile cells. Depending...... on the loading conditions, the additional stress needed to break the cells can indeed be smaller due to the initial thermo-mechanical stress state. The residual stresses can for a bilayer cell be approximated by estimating the temperature at which elastic stresses start to build up during the cooling, i...
Measured residual stresses in overlay pipe weldments removed from service

International Nuclear Information System (INIS)

Shack, W.J.

1985-02-01

Surface and throughwall residual stresses were measured on an elbow-to-pipe weldment that had been removed from the Hatch-2 reactor about a year after the application of a weld overlay. The results were compared with experimental measurements on three mock-up weldments and with finite-element calculations. The comparison shows that there are significant differences in the form and magnitude of the residual stress distributions. However, even after more than a year of service, the residual stresses over most of the inner surface of the actual plant weldment with an overlay were strongly compressive. 3 refs., 7 figs
FIB-based measurement of local residual stresses on microsystems

Science.gov (United States)

Vogel, Dietmar; Sabate, Neus; Gollhardt, Astrid; Keller, Juergen; Auersperg, Juergen; Michel, Bernd

2006-03-01

The paper comprises research results obtained for stress determination on micro and nanotechnology components. It meets the concern of controlling stresses introduced to sensors, MEMS and electronics devices during different micromachining processes. The method bases on deformation measurement options made available inside focused ion beam equipment. Removing locally material by ion beam milling existing stresses / residual stresses lead to deformation fields around the milled feature. Digital image correlation techniques are used to extract deformation values from micrographs captured before and after milling. In the paper, two main milling features have been analyzed - through hole and through slit milling. Analytical solutions for stress release fields of in-plane stresses have been derived and compared to respective experimental findings. Their good agreement allows to settle a method for determination of residual stress values, which is demonstrated for thin membranes manufactured by silicon micro technology. Some emphasis is made on the elimination of main error sources for stress determination, like rigid body object displacements and rotations due to drifts of experimental conditions under FIB imaging. In order to illustrate potential application areas of the method residual stress suppression by ion implantation is evaluated by the method and reported here.
Analysis of residual stress relief mechanisms in post-weld heat treatment

International Nuclear Information System (INIS)

Dong, Pingsha; Song, Shaopin; Zhang, Jinmiao

2014-01-01

This paper presents a recent study on weld residual stress relief mechanisms associated with furnace-based uniform post-weld heat treatment (PWHT). Both finite element and analytical methods are used to quantitatively examine how plastic deformation and creep relaxation contribute to residual stress relief process at different stages of PWHT process. The key contribution of this work to an improved understanding of furnace based uniform PWHT can be summarized as follows: (1)Plastic deformation induced stress relief during PWHT can be analytically expressed by the change in material elastic deformation capacity (or elastic deformation limit) measured in terms of material yield strength to Young's modulus ratio, which has a rather limited role in overall residual stress relief during furnace based uniform PWHT. (2)The most dominant stress relief mechanism is creep strain induced stress relaxation, as expected. However, a rapid creep strain development accompanied by a rapid residual stress reduction during heating stage before reaching PWHT temperature is shown to contribute to most of the stress relief seen in overall PWHT process, suggesting PWHT hold time can be significantly reduced as far as residual stress relief is concerned. (3)A simple engineering scheme for estimating residual stress reduction is proposed based on this study by relating material type, PWHT temperature, and component wall thickness. - Highlights: • The paper clarified effects of plastic deformation and creep relaxation on weld residual stress relief during uniform PWHT. • Creep strain development is far more important than plastic strain, mostly completed even before hold time starts. • Plastic strain development is insignificant and be analytically described by a material elastic deformation capacity parameter. • An engineering estimation scheme is proposed for determining residual stress reduction resulted from furnace based PWHT

Effect of residual stress on the integrity of a branch connection

International Nuclear Information System (INIS)

Law, M.; Kirstein, O.; Luzin, V.

2012-01-01

A new connection to an existing gas pipeline was made by hot-tapping, welding directly onto a pressurised pipeline. The welds were not post-weld heat treated, causing significant residual stresses. The critical weld had residual stresses determined by neutron diffraction using ANSTO's residual stress diffractometer, Kowari. The maximum measured residual stress (290 MPa) was 60% of the yield strength. The magnitudes of errors from a number of sources were estimated. An integrity assessment of the welded branch connection was performed with the measured residual stress values and with residual stress distributions from the BS 7910 and API 579 analysis codes. Analysis using estimates of residual stress from API 579 overestimated the critical crack size. Highlights: ► Residual stresses were measured by neutron diffraction in a thick section, non post-weld heat treated ferritic weld. ► There is little published data on these welds. ► The work compares the measured residual stresses with code-based residual stress distributions.
Residual stress measurement in 304 stainless steel weld overlay pipes

International Nuclear Information System (INIS)

Yen, H.J.; Lin, M.C.C.; Chen, L.J.

1996-01-01

Welding overlay repair (WOR) is commonly employed to rebuild piping systems suffering from intergranular stress corrosion cracking (IGSCC). To understand the effects of this repair, it is necessary to investigate the distribution of residual stresses in the welding pipe. The overlay welding technique must induce compressive residual stress at the inner surface of the welded pipe to prevent IGSCC. To understand the bulk residual stress distribution, the stress profile as a function of location within wall is examined. In this study the full destructive residual stress measurement technique -- a cutting and sectioning method -- is used to determine the residual stress distribution. The sample is type 304 stainless steel weld overlay pipe with an outside diameter of 267 mm. A pipe segment is cut from the circular pipe; then a thin layer is removed axially from the inner to the outer surfaces until further sectioning is impractical. The total residual stress is calculated by adding the stress relieved by cutting the section away to the stress relieved by axially sectioning. The axial and hoop residual stresses are compressive at the inner surface of the weld overlay pipe. Compressive stress exists not only at the surface but is also distributed over most of the pipe's cross section. On the one hand, the maximum compressive hoop residual stress appears at the pipe's inner surface. The thermal-mechanical induced crack closure from significant compressive residual stress is discussed. This crack closure can thus prevent IGSCC very effectively
Investigation of surface residual stress profile on martensitic stainless steel weldment with X-ray diffraction

Directory of Open Access Journals (Sweden)

I.I. Ahmed

2018-04-01

Full Text Available The development of residual stresses during fabrication is inevitable and often neglected with dire consequences during the service life of the fabricated components. In this work, the surface residual stress profile following the martensitic stainless steel (MSS pipe welding was investigated with X-ray diffraction technique. The results revealed the presence of residual stresses equilibrated across the weldment zones. Tensile residual stress observed in weld metal was balanced by compressive residual stresses in the parent material on the opposing sides of weld metal. Keywords: Residual stress, Weld, Stainless steel, X-ray, HAZ
Characterization of Residual Stress Effects on Fatigue Crack Growth of a Friction Stir Welded Aluminum Alloy

Science.gov (United States)

Newman, John A.; Smith, Stephen W.; Seshadri, Banavara R.; James, Mark A.; Brazill, Richard L.; Schultz, Robert W.; Donald, J. Keith; Blair, Amy

2015-01-01

An on-line compliance-based method to account for residual stress effects in stress-intensity factor and fatigue crack growth property determinations has been evaluated. Residual stress intensity factor results determined from specimens containing friction stir weld induced residual stresses are presented, and the on-line method results were found to be in excellent agreement with residual stress-intensity factor data obtained using the cut compliance method. Variable stress-intensity factor tests were designed to demonstrate that a simple superposition model, summing the applied stress-intensity factor with the residual stress-intensity factor, can be used to determine the total crack-tip stress-intensity factor. Finite element, VCCT (virtual crack closure technique), and J-integral analysis methods have been used to characterize weld-induced residual stress using thermal expansion/contraction in the form of an equivalent delta T (change in local temperature during welding) to simulate the welding process. This equivalent delta T was established and applied to analyze different specimen configurations to predict residual stress distributions and associated residual stress-intensity factor values. The predictions were found to agree well with experimental results obtained using the crack- and cut-compliance methods.
The method for measuring residual stress in stainless steel pipes

International Nuclear Information System (INIS)

Shimov, Georgy; Rozenbaum, Mikhail; Serebryakov, Alexandr; Serebryakov, Andrey

2016-01-01

The main reason of appearance and growth of corrosion damages of the nuclear steam generator heat exchanger tubes is the process of stress-corrosion cracking of metal under the influence of residual tensile stress. Methods used in the production for estimating residual stresses (such as a method of ring samples) allow measuring only the average tangential stress of the pipe wall. The method of ring samples does not allow to assess the level of residual stress in the surface layer of the pipe. This paper describes an experimental method for measuring the residual stresses on the pipe surface by etching a thin surface layer of the metal. The construction and working principle of a trial installation are described. The residual stresses in the wall of the tubes 16 × 1.5 mm (steel AISI 321) for nuclear steam generators is calculated. Keywords: heat exchange pipes, stress corrosion cracking, residual stresses, stress distribution, stress measurement.
Surface residual stress evaluation in double-electrode butt welded steel plates

International Nuclear Information System (INIS)

Estefen, S.F.; Gurova, T.; Castello, X.; Leontiev, A.

2010-01-01

Surface residual stress evaluation for double-electrode welding was studied. The stresses were monitored after each operational step: positioning, implementing of constraints, welding and constraints removal. The measurements were performed at the deposited metal, heat affected zone, base metal close to the weld joint and along the plate using the X-ray diffraction method. It was observed differences in the stress evaluations for double-electrode welding which resulted in lower bending distortions and higher values of surface residual stresses, compared with single-electrode welding. This behavior is associated with the stress distribution just after the welding processes in both heat affected zone and base metal close to the fillet for double-electrode welding. The main results from the laboratorial tests indicated lower values of the bending distortions for double-electrode welding compared with the single-electrode. In relation to the residual stress, the double-electrode welding generated, in general, higher stress values in both longitudinal and transversal directions.
Residual stress measurements by means of neutron diffraction

International Nuclear Information System (INIS)

Pintschovius, L.; Jung, V.; Macherauch, E.; Voehringer, O.

1983-01-01

A new method for the analysis of multiaxial residual stress states is presented, which is based on high resolution neutron diffraction. It is analogous to X-ray stress analysis, but the use of neutrons instead of X-rays allows the analysis of the stress distributions also in the interior of technical components in a non-destructive way. To prove the feasibility of the method, investigations of the loading stress distributions of an aluminium bar subjected to purely elastic bending were performed. Limiting factors due to the volume of the internal probe region and the sample thickness are discussed. Complete neutron residual stress analyses were carried out for a plastically deformed bending bar and a transformation-free water-quenched steel cylinder. The results are in fairly good agreement with theoretical expectations and with X-ray control measurements at the surface of the objects. (Auth.)
Residual stress effects in LMFBR fracture assessment procedures

International Nuclear Information System (INIS)

Hooton, D.G.

1984-01-01

Two post-yield fracture mechanics methods, which have been developed into fully detailed failure assessment procedures for ferritic structures, have been reviewed from the point of view of the manner in which as-welded residual stress effects are incorporated, and comparisons then made with finite element and theoretical models of centre-cracked plates containing residual/thermal stresses in the form of crack-driving force curves. Applying the procedures to austenitic structures, comparisons are made in terms of failure assessment curves and it is recommended that the preferred method for the prediction of critical crack sizes in LMFBR austenitic structures containing as-welded residual stresses is the CEGB-R6 procedure based on a flow stress defined at 3% strain in the parent plate. When the prediction of failure loads in such structures is required, it is suggested that the CEGB-R6 procedure be used with residual/thermal stresses factored to give a maximum total stress of flow stress magnitude
Laser quench hardening of steel: Effects of superimposed elastic pre-stress on the hardness and residual stress distribution

Science.gov (United States)

Meserve, Justin

Cold drawn AISI 4140 beams were LASER surface hardened with a 2 kW CO2 LASER. Specimens were treated in the free state and while restrained in a bending fixture inducing surface tensile stresses of 94 and 230 MPa. Knoop hardness indentation was used to evaluate the through thickness hardness distribution, and a layer removal methodology was used to evaluate the residual stress distribution. Results showed the maximum surface hardness attained was not affected by pre-stress during hardening, and ranged from 513 to 676 kg/mm2. The depth of effective hardening varied at different magnitudes of pre-stress, but did not vary proportionately to the pre-stress. The surface residual stress, coinciding with the maximum compressive residual stress, increased as pre-stress was increased, from 1040 MPa for the nominally treated specimens to 1270 MPa for specimens pre-stressed to 230 MPa. The maximum tensile residual stress observed in the specimens decreased from 1060 MPa in the nominally treated specimens to 760 MPa for specimens pre-stressed to 230 MPa. Similarly, thickness of the compressive residual stress region increased and the depth at which maximum tensile residual stress occurred increased as the pre-stress during treatment was increased Overall, application of tensile elastic pre-stress during LASER hardening is beneficial to the development of compressive residual stress in AISI 4140, with minimal impact to the hardness attained from the treatment. The newly developed approach for LASER hardening may support efforts to increase both the wear and fatigue resistance of parts made from hardenable steels.
Modelling of the Residual Stress State in a new Type of Residual Stress Specimen

DEFF Research Database (Denmark)

Jakobsen, Johnny; Andreasen, Jens Henrik

2014-01-01

forms the experimental case which is analysed. A FE model of the specimen is used for analysing the curing history and the residual stress build up. The model is validated against experimental strain data which are recorded by a Fibre Brag Grating sensor and good agreement has been achieved.......The paper presents a study on a new type residual stress specimen which is proposed as a simple way to conduct experimental validation for model predictions. A specimen comprising of a steel plate with circular hole embedded into a stack of CSM glass fibre and further infused with an epoxy resin...
Mapping residual stresses in PbWO4 crystals using photo-elastic analysis

International Nuclear Information System (INIS)

Lebeau, M.; Gobbi, L.; Majni, G.; Paone, N.; Pietroni, P.; Rinaldi, D.

2005-01-01

Large scintillating crystals are affected by internal stresses induced by the crystal growth temperature gradient remanence. Cutting boules (ingots) into finished crystal shapes allows for a partial tension relaxation but residual stresses remain the main cause of breaking. Quality control of residual stresses is essential in the application of Scintillating Crystals to high-energy physics calorimeters (e.g. CMS ECAL at CERN LHC). In this context the industrial process optimisation towards stress reduction is mandatory. We propose a fast technique for testing samples during the production process in order to evaluate the residual stress distribution after the first phases of mechanical processing. We mapped the stress distribution in PbWO 4 slabs cut from the same production boule. The analysis technique is based on the stress intensity determination using the photo-elastic properties of the samples. The stress distribution is mapped in each sample. The analysis shows that there are regions of high residual tension close to the seed position and at the boule periphery. These results should allow for adapting the industrial process to producing crystals with lower residual stresses
Evaluation of residual stresses in welded part using hard synchrotron x-rays

International Nuclear Information System (INIS)

Suzuki, Kenji; Shobu, Takahisa; Shiro, Ayumi; Zhang Shuoyuan

2013-01-01

The spiral slit-system and DSTM (diffraction spot trace method) are under development in order to evaluate internal stresses of materials with coarse grains. The spiral slit-system was improved so that the length of the gauge volume is independent of the diffraction angle. The bending stress in the specimen with coarse grains was measured in order to confirm performance of this advanced spiral slit-system. The distribution of the measured bending stress coincided with the applied bending stress. As a result, it was proved that the combination of the advanced spiral slit-system and the DSTM is useful for the internal stress measurement of materials with coarse grains. The welded specimen of a Mg-alloy plate was prepared by melt-run with TIG welding. The residual stress map in the cross-section of the specimen was made using the DSTM. On the other hand, the residual stresses of the welded specimen were simulated by a finite element method. Although the measured residual stresses were similar to the simulated results, the residual stresses due to extrusion were measured also using the DSTM. The DSTM is an excellent technique for the stress measurement of weld parts. (author)
Joining U.S. NRC international round robin for weld residual stress analysis. Stress analysis and validation in PWSCC mitigation program

International Nuclear Information System (INIS)

Maekawa, Akira; Serizawa, Hisashi; Murakawa, Hidekazu

2012-01-01

It is necessary to establish properly reliable weld residual stress analysis methods for accurate crack initiation and growth assessment of primary water stress corrosion cracking (PWSCC), which may occur in nickel-based dissimilar metal welds in pressurized water reactors. The U.S. Nuclear Regulatory Commission conducted an international round robin for weld residual stress analysis to improve stress analysis methods and to examine the uncertainties involved in the calculated stress values. In this paper, the results from the authors' participation in the round robin were reported. In the round robin, the weld residual stress in a nickel-based dissimilar metal weld of a pressurizer surge nozzle mock-up was computed under various analysis conditions. Based on these residual stress analysis results, a welding simulation code currently being developed that uses the iterative substructure method was validated and affecting factors on the analysis results were identified. (author)
Systematic Review of Uit Parameters on Residual Stresses of Sensitized AA5456 and Field Based Residual Stress Measurements for Predicting and Mitigating Stress Corrosion Cracking

Science.gov (United States)

2014-03-01

University Press, 2009, pp. 820–824. [30] S. Kou, Welding Metallurgy , 2nd ed. Hoboken, NJ: John Wiley and Sons, Inc., 2003. [31] M. N.James et al...around welds in aluminum ship structures both in the laboratory and in the field. Tensile residual stresses are often generated during welding and, in...mitigate and even reverse these tensile residual stresses. This research uses x-ray diffraction to measure residual stresses around welds in AA5456 before
Control of welding residual stress for ensuring integrity against fatigue and stress-corrosion cracking

International Nuclear Information System (INIS)

Mochizuki, Masahito

2007-01-01

The availability of several techniques for residual stress control is discussed in this paper. The effectiveness of these techniques in protecting from fatigue and stress-corrosion cracking is verified by numerical analysis and actual experiment. In-process control during welding for residual stress reduction is easier to apply than using post-weld treatment. As an example, control of the welding pass sequence for multi-pass welding is applied to cruciform joints and butt-joints with an X-shaped groove. However, residual stress improvement is confirmed for post-weld processes. Water jet peening is useful for obtaining a compressive residual stress on the surface, and the tolerance against both fatigue and stress-corrosion cracking is verified. Because cladding with a corrosion-resistant material is also effective for preventing stress-corrosion cracking from a metallurgical perspective, the residual stress at the interface of the base metal is carefully considered. The residual stress of the base metal near the clad edge is confirmed to be within the tolerance of crack generation. Controlling methods both during and after welding processes are found to be effective for ensuring the integrity of welded components
Residual stresses in laser direct metal deposited Waspaloy

Energy Technology Data Exchange (ETDEWEB)

Moat, R.J., E-mail: richard.moat@manchester.ac.uk [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom); Pinkerton, A.J.; Li, L. [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, M60 1QD (United Kingdom); Withers, P.J.; Preuss, M. [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom)

2011-03-15

Research highlights: {yields} Neutron diffraction and the contour method show good agreement. {yields} Tensile stresses found parallel to the surfaces. {yields} Compressive stresses within the bulk of the structures. {yields} Residual stress weakly dependent on the laser pulse parameters. {yields} Maximum tensile residual stress unaffected across range of pulse parameters used. - Abstract: This paper reports a study into the effect of laser pulse length and duty cycle on the residual stress distributions in multi-track laser direct metal deposits of Waspaloy onto an Inconel 718 substrate. The residual stresses have been evaluated using neutron diffraction and the contour method, while electron microscopy and micro hardness indentation have been used to map the concomitant microstructural variation. In all cases, near the tops of the deposited walls, the longitudinal stresses are tensile towards the mid-length of the wall, while the stresses perpendicular to the substrate are negligible. By contrast near the base of the walls, the stresses along the direction of deposition are small, while the stresses perpendicular to the substrate are compressive at the centre and tensile towards the ends. Consistent with previous observations, the stresses parallel to free surfaces are tensile, balanced by compressive stresses in the interior (an inverse quench stress profile). These profiles have been found to be weakly dependent on the laser pulse parameters, most notably an increase in tensile stress gradient with increasing duty cycle, but the maximum residual stresses are largely unaffected. Furthermore, microstructural analysis has shown that the effect of laser pulse parameters on grain morphology in multi-track thick walls is less marked than previously reported for single-track wall structures.
Residual stresses in laser direct metal deposited Waspaloy

International Nuclear Information System (INIS)

Moat, R.J.; Pinkerton, A.J.; Li, L.; Withers, P.J.; Preuss, M.

2011-01-01

Research highlights: → Neutron diffraction and the contour method show good agreement. → Tensile stresses found parallel to the surfaces. → Compressive stresses within the bulk of the structures. → Residual stress weakly dependent on the laser pulse parameters. → Maximum tensile residual stress unaffected across range of pulse parameters used. - Abstract: This paper reports a study into the effect of laser pulse length and duty cycle on the residual stress distributions in multi-track laser direct metal deposits of Waspaloy onto an Inconel 718 substrate. The residual stresses have been evaluated using neutron diffraction and the contour method, while electron microscopy and micro hardness indentation have been used to map the concomitant microstructural variation. In all cases, near the tops of the deposited walls, the longitudinal stresses are tensile towards the mid-length of the wall, while the stresses perpendicular to the substrate are negligible. By contrast near the base of the walls, the stresses along the direction of deposition are small, while the stresses perpendicular to the substrate are compressive at the centre and tensile towards the ends. Consistent with previous observations, the stresses parallel to free surfaces are tensile, balanced by compressive stresses in the interior (an inverse quench stress profile). These profiles have been found to be weakly dependent on the laser pulse parameters, most notably an increase in tensile stress gradient with increasing duty cycle, but the maximum residual stresses are largely unaffected. Furthermore, microstructural analysis has shown that the effect of laser pulse parameters on grain morphology in multi-track thick walls is less marked than previously reported for single-track wall structures.
Measuring depth profiles of residual stress with Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Enloe, W.S.; Sparks, R.G.; Paesler, M.A.

1988-12-01

Knowledge of the variation of residual stress is a very important factor in understanding the properties of machined surfaces. The nature of the residual stress can determine a part`s susceptibility to wear deformation, and cracking. Raman spectroscopy is known to be a very useful technique for measuring residual stress in many materials. These measurements are routinely made with a lateral resolution of 1{mu}m and an accuracy of 0.1 kbar. The variation of stress with depth; however, has not received much attention in the past. A novel technique has been developed that allows quantitative measurement of the variation of the residual stress with depth with an accuracy of 10nm in the z direction. Qualitative techniques for determining whether the stress is varying with depth are presented. It is also demonstrated that when the stress is changing over the volume sampled, errors can be introduced if the variation of the stress with depth is ignored. Computer aided data analysis is used to determine the depth dependence of the residual stress.
Modeling of plates with multiple anisotropic layers and residual stress

DEFF Research Database (Denmark)

Engholm, Mathias; Pedersen, Thomas; Thomsen, Erik Vilain

2016-01-01

Usually the analytical approach for modeling of plates uses the single layer plate equation to obtain the deflection and does not take anisotropy and residual stress into account. Based on the stress–strain relation of each layer and balancing stress resultants and bending moments, a general...... multilayered anisotropic plate equation is developed for plates with an arbitrary number of layers. The exact deflection profile is calculated for a circular clamped plate of anisotropic materials with residual bi-axial stress.From the deflection shape the critical stress for buckling is calculated......, and an excellent agreement between the two models is seen with a relative difference of less than 2% for all calculations. The model was also used to extract the cell capacitance, the parasitic capacitance and the residual stress of a pressure sensor composed of a multilayered plate of silicon and silicon oxide...
Residual stress measurement of the jacket material for ITER coil by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Tsuchiya, Yoshinori [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-03-01

Nickel-Iron based super alloy INCOLOY 908 is used for the jacket of a central solenoid coil (CS coil) of the International Thermonuclear Experimental Reactor (ITER). INCOLOY 908, however, has a possibility of fracture due to Stress Accelerated Grain Boundary Oxidation (SAGBO) under a tensile residual stress beyond 200MPa. Therefore it is necessary to measure the residual stress of the jacket to avoid SAGBO. We performed residual stress measurement of the jacket by neutron diffraction using the neutron diffractometer for residual stress analysis (RESA) installed at JRR-3M in JAERI. A sample depth dependence of internal strain was obtained from the (111) plane spacing. A residual stress distribution was calculated from the strain using Young`s modulus and Poisson`s ratio that were evaluated by a tensile test with neutron diffraction. The result shows that the tensile residual stress exceeds 200MPa of the SAGBO condition in some regions inside the jacket. (author)

Residual stresses determination in an 8 mm Incoloy 800H weld via neutron diffraction

International Nuclear Information System (INIS)

Chen, Xizhang; Zhang, Shu Yan; Wang, Jingjun; Kelleher, Joe F.

2015-01-01

Highlights: • Stress through thickness at 5 mm from weld centerline indicates a “U” distribution. • Declining of tensile stress through thickness occurred at weld centerline. • Residual stress between layers is the lowest. - Abstract: To investigate the distribution of residual stresses, the 8 mm 800H alloy was joined by multi-layer butt TIG process. Residual stresses in the longitudinal, transverse and normal directions were measured via neutron diffraction. These residual stress measurements were taken at a series of points 2 mm below the top surface, covering the fusion zone, heat affected zone (HAZ) and base metal. In addition, two lines of longitudinal residual stress values at the weld centerline and 5 mm from weld centerline through thickness were measured. Results show that both the longitudinal and transverse stresses from the weld centerline to base metal are mainly tensile stresses. The longitudinal residual stress is the largest, with a maximum value of 330 MPa. As for the normal residual stress, the weld zone shows tensile stress, while the HAZ shows compressive stress. The middle of the thickness shows compressive residual stress along the thickness direction. The longitudinal stress at weld centerline through thickness reveals the interlayer heat treat effects leads to a declining of tensile stress. While the stress at 5 mm from weld centerline indicates a “U” distribution due to the mixed microstructure close to fusion line. With the increasing distance from weld seam, the residual stress decreases gradually
Numerical simulation of residual stress in laser based additive manufacturing process

Science.gov (United States)

Kalyan Panda, Bibhu; Sahoo, Seshadev

2018-03-01

Minimizing the residual stress build-up in metal-based additive manufacturing plays a pivotal role in selecting a particular material and technique for making an industrial part. In beam-based additive manufacturing, although a great deal of effort has been made to minimize the residual stresses, it is still elusive how to do so by simply optimizing the processing parameters, such as beam size, beam power, and scan speed. Amid different types of additive manufacturing processes, Direct Metal Laser Sintering (DMLS) process uses a high-power laser to melt and sinter layers of metal powder. The rapid solidification and heat transfer on powder bed endows a high cooling rate which leads to the build-up of residual stresses, that will affect the mechanical properties of the build parts. In the present work, the authors develop a numerical thermo-mechanical model for the measurement of residual stress in the AlSi10Mg build samples by using finite element method. Transient temperature distribution in the powder bed was assessed using the coupled thermal to structural model. Subsequently, the residual stresses were estimated with varying laser power. From the simulation result, it found that the melt pool dimensions increase with increasing the laser power and the magnitude of residual stresses in the built part increases.
Optimization of Residual Stress of High Temperature Treatment Using Genetic Algorithm and Neural Network

Directory of Open Access Journals (Sweden)

M. Susmikanti

2015-12-01

Full Text Available In a nuclear industry area, high temperature treatment of materials is a factor which requires special attention. Assessment needs to be conducted on the properties of the materials used, including the strength of the materials. The measurement of material properties under thermal processes may reflect residual stresses. The use of Genetic Algorithm (GA to determine the optimal residual stress is one way to determine the strength of a material. In residual stress modeling with several parameters, it is sometimes difficult to solve for the optimal value through analytical or numerical calculations. Here, GA is an efficient algorithm which can generate the optimal values, both minima and maxima. The purposes of this research are to obtain the optimization of variable in residual stress models using GA and to predict the center of residual stress distribution, using fuzzy neural network (FNN while the artificial neural network (ANN used for modeling. In this work a single-material 316/316L stainless steel bar is modeled. The minimal residual stresses of the material at high temperatures were obtained with GA and analytical calculations. At a temperature of 6500C, the GA optimal residual stress estimation converged at –711.3689 MPa at adistance of 0.002934 mm from center point, whereas the analytical calculation result at that temperature and position is -975.556 MPa . At a temperature of 8500C, the GA result was -969.868 MPa at 0.002757 mm from the center point, while with analytical result was -1061.13 MPa. The difference in residual stress between GA and analytical results at a temperatureof6500C is about 27 %, while at 8500C it is 8.67 %. The distribution of residual stress showed a grouping concentrated around a coordinate of (-76; 76 MPa. The residuals stress model is a degree-two polynomial with coefficients of 50.33, -76.54, and -55.2, respectively, with a standard deviation of 7.874.
Prediction of retained residual stresses in laboratory fracture mechanics specimens extracted from welded components

International Nuclear Information System (INIS)

Hurlston, R.G.; Sherry, A.H.; James, P.; Sharples, J.K.

2015-01-01

The measurement of weld material fracture toughness properties is important for the structural integrity assessment of engineering components. However, welds can contain high levels of residual stress and these can be retained in fracture mechanics specimens, particularly when machined from non-stress relieved welds. Retained residual stresses can make the measurement of valid fracture toughness properties difficult. This paper describes the results of analytical work undertaken to investigate factors that can influence the magnitude and distribution of residual stresses retained in fracture mechanics specimen blanks extracted from as-welded ferritic and austenitic stainless steel plates. The results indicate that significant levels of residual stress can be retained in specimen blanks prior to notching, and that the magnitude and distribution of stress is dependent upon material properties, specimen geometry and size, and extraction location through the thickness of the weld. Finite element modelling is shown to provide a useful approach for estimating the level and distributions of retained residual stresses. A new stress partitioning approach has been developed to estimate retained stress levels and results compare favourably with FE analysis and available experimental data. The approach can help guide the selection of specimen geometry and machining strategies to minimise the level of residual stresses retained in fracture mechanics specimen blanks extracted from non stress-relieved welds and thus improve the measurement of weld fracture toughness properties. - Highlights: • A simplified method for generating realistic weld residual stresses has been developed. • It has been shown that significant levels of residual stress can be retained within laboratory fracture mechanics specimens. • The level and distribution is dependant upon material, specimen type, specimen size and extraction location. • A method has been developed to allow estimates of the
A study on residual stress mitigation of the HDPE pipe for various annealing conditions

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Sung [Sunchon National University, Sunchon (Korea, Republic of); Yoo, Jeong Ho [Korea Laboratory Engineering System, Daejeon (Korea, Republic of); Oh, Young Jin [KEPCO E and C, Sungnam (Korea, Republic of)

2015-03-15

This paper presents effects of the annealing condition variables such as temperature and time on the residual stress mitigation. The effects were investigated by using the various measurement methods such as hole-drilling method and slitting method. As a result of the investigation, the residual stress mitigation magnitude increases with increasing the annealing time and temperature. Based on the investigation results, the quantitative correlations between the annealing variables and the residual stress mitigation were derived. Finally, the effect of long-term operation under the normal operating temperature conditions on the residual stress mitigation was investigated by referring to the derived equations and performing some additional tests, and it is identified that the residual stresses are not significantly relaxed over the design lifetime of the safety class III buried HDPE pipes.
Residual stress measurement in socket welded joints by neutron diffraction

International Nuclear Information System (INIS)

Hayashi, Makoto; Ishiwata, Masayuki; Minakawa, Noriaki; Funahashi, Satoru.

1995-01-01

Neutron diffraction measurements of lattice spacings provide the spatial map of residual stress near welds in ferritic steel socket joints. The high tensile stress greater than 200 MPa was found in the fusion and heat-affected zones in the hoop direction. However, the highest tensile stress in the axial direction at the weld root was about 110 MPa relatively lower than the expected value from the fatigue test results. The balancing compressive stress was found near the surface of the socket weld fusion zone. Heat treatment at 625degC for 2 hours was sufficient for the relief of residual stress in socket welds. (author)
Residual stresses in a weldment of pressure vessel steel

International Nuclear Information System (INIS)

Gott, K.E.

1978-01-01

A study was made of the distribution of residual stresses around a typical weld from a light water reactor pressure vessel by an X-ray double-exposure camera technique. So that the magnitude, sign, and distribution of the residual stresses were as similar as possible to those found in practice, a wide, full-thickness specimen of A533B Cl 1 steel containing a submerged-arc weld was stress-relief annealed. To obtain a three-dimensional distribution of the stresses the specimen was examined at different levels through the thickness. Following the removal of material by milling, the specimen surface was electropolished to free it from cold work. Corrections have been made to take into account specimen relaxation. To completely define the original stress system it is desirable also to measure the change in curvature on removing a layer of material. Unless this is done assumptions must be made which complicate the calculations unnecessarily. This became apparent after the experimental work was completed. In the centre of the plate the methods of correction which can be used are sensitive to errors in the measurements. The corrected results show that the dominant residual stress is perpendicular to the weld. It is positive at the surfaces and negative in the centre of the plate. The maximum value can reach the yield stress. The residual stresses in the weld metal can locally vary considerably: from 100 to 350N/mm 2 over a distance of 5mm. Such large variations have been found to coincide with the heat-affected zones of the individual weld runs. (author)
X-ray study of residual stress distribution of ground ceramics

International Nuclear Information System (INIS)

Sakaida, Yoshihisa; Tanaka, Keisuke; Ikuhara, Yuichi; Suzuki, Kenzi.

1997-01-01

The residual stress distribution of ground ceramics was determined from the eigen strain existing in the ground surface. The eigen strain of ground ceramics was tensile, and exponentially decreased with the distance from the surface. The residual stress distribution is given as a superposition of an exponential function of compression and a linear function. It is found that the actual residual stress distribution can be approximated by a compressive exponential function because the magnitude of tensile residual stress is negligibly small compared to the compressive residual stress. In the experiments, the diffraction angle was measured on ground silicon nitride for a wide range of sin 2 ψ using the glancing incidence X-ray diffraction technique. A strong nonlinearity was found in the 2θ-sin 2 ψ diagram at very high ψ-angles. From the analysis of nonlinearity, the residual stress distribution was determined. The residual stress distribution of silicon nitride coincided with the distribution calculated from the eigen strain distribution. Transmission electron microscopy was used to clarify the origin of generation of the residual stress. Both strain contrasts and microcracks were observed below the ground surface ; straight dislocations were also observed within silicon nitride grains near the ground surface. (author)
Nonlinear morphoelastic plates I: Genesis of residual stress

KAUST Repository

McMahon, J.

2011-04-28

Volumetric growth of an elastic body may give rise to residual stress. Here a rigorous analysis is given of the residual strains and stresses generated by growth in the axisymmetric Kirchhoff plate. Balance equations are derived via the Global Constraint Principle, growth is incorporated via a multiplicative decomposition of the deformation gradient, and the system is closed by a response function. The particular case of a compressible neo-Hookean material is analyzed, and the existence of residually stressed states is established. © SAGE Publications 2011.
Nonlinear morphoelastic plates I: Genesis of residual stress

KAUST Repository

McMahon, J.; Goriely, A.; Tabor, M.

2011-01-01

Volumetric growth of an elastic body may give rise to residual stress. Here a rigorous analysis is given of the residual strains and stresses generated by growth in the axisymmetric Kirchhoff plate. Balance equations are derived via the Global Constraint Principle, growth is incorporated via a multiplicative decomposition of the deformation gradient, and the system is closed by a response function. The particular case of a compressible neo-Hookean material is analyzed, and the existence of residually stressed states is established. © SAGE Publications 2011.
Influence of ion irradiation on internal residual stress in DLC films

Energy Technology Data Exchange (ETDEWEB)

Karaseov, Platon A., E-mail: platon.karaseov@rphf.spbstu.r [St. Petersburg State Polytechnic University, Polytechnicheskaya St. 29, 195251 St. Petersburg (Russian Federation); Podsvirov, Oleg A.; Karabeshkin, Konstantin V. [St. Petersburg State Polytechnic University, Polytechnicheskaya St. 29, 195251 St. Petersburg (Russian Federation); Vinogradov, Andrei Ya. [Ioffe Physicotechnical Institute RAS, Polytechnicheskaya 26, 195252 St. Petersburg (Russian Federation); Azarov, Alexander Yu. [St. Petersburg State Polytechnic University, Polytechnicheskaya St. 29, 195251 St. Petersburg (Russian Federation); Karasev, Nikita N. [State University of Information Technologies, Mechanics and Optics, Sablinskaya Str. 14, 197101 St. Petersburg (Russian Federation); Titov, Andrei I.; Smirnov, Alexander S. [St. Petersburg State Polytechnic University, Polytechnicheskaya St. 29, 195251 St. Petersburg (Russian Federation)

2010-10-01

The dependence of internal residual stress in thin diamond-like carbon films grown on Si substrate by PECVD technique on most important growth parameters, namely RF-power, DC bias voltage and substrate temperature, is described. Results show that compressive stress reaches the highest value of 2.7 GPa at low RF-power and DC bias. Increase of substrate temperature from 250 to 350 {sup o}C leads to nonlinear increase of stress value. Inhomogeneity of residual stress along the film surface disappears when film is deposited at temperatures above 275 {sup o}C. Post-growth film irradiation by P{sup +} and In{sup +} ions cause decrease of compressive stress followed by its inversion to tensile. For all ion energy combinations used residual stress changes linearly with normalized fluence up to 0.2 DPA with slope (8.7 {+-} 1.3) GPa/DPA.
Residual stress characterization of welds using x-ray diffraction techniques

International Nuclear Information System (INIS)

Pineault, J.A.; Brauss, M.E.

1996-01-01

Neglect of residual stresses created during processes lead to stress corrosion cracking, distortion, fatigue cracking, premature failures in components, and instances of over design. Automated residual stress mapping and truly portable equipment have now made the characterization of residual stresses using x-ray diffraction (XRI) practical. The nondestructive nature of the x-ray diffraction technique has made the tile residual stress characterization of welds a useful tool for process optimization and failure analysis, particularly since components can be measured before and after welding and post welding processes. This paper illustrates the importance of residual stress characterization in welds and presents examples where x-ray diffraction techniques were applied in the characterization of various kinds of welds. arc welds, TIG welds, resistance welds, laser welds and electron beam welds. Numerous techniques are available to help manage potentially harmfull residual stresses created during the welding process thus, the effects of a few example post weld processes such as grinding, heat treating and shot peening are also addressed
Comparison of residual stress measurement in thin films using surface micromachining method

International Nuclear Information System (INIS)

He, Q.; Luo, Z.X.; Chen, X.Y.

2008-01-01

Conductive, dielectric, semiconducting, piezoelectric and ferroelectric thin films are extensively used for MEMS/NEMS applications. One of the important parameters of thin films is residual stress. The residual stress can seriously affect the properties, performance and long-term stability of the films. Excessive compressive or tensile stress results in buckling, cracking, splintering and sticking problems. Stress measurement techniques are therefore essential for both process development and process monitoring. Many suggestions for stress measurement in thin films have been made over the past several decades. This paper is concentrated on the in situ stress measurement using surface micromachining techniques to determine the residual stress. The authors review and compare several types of stress measurement methods including buckling technique, rotating technique, micro strain gauge and long-short beam strain sensor
NUMERICAL AND EXPERIMENTAL ANALYSIS OF RESIDUAL STRESSES GENERATED DURING HARDENING OFAISI 4140 BAR

Directory of Open Access Journals (Sweden)

Edwan Anderson Ariza Echeverri

2012-09-01

Full Text Available The aim of this work is to analyze the distribution of residual stresses resulting from the combination of volumetric changes due to heat gradients and phase changes occurring during the quenching process of an AISI/SAE 4140 steel cylinder. The mathematical model used for this objective is the AC3 modeling software of thermal treatments (transformation curves, cooling curves and microstructure, whose results were input in an finite element model, considering thermalmechanical coupling and non-linear elastic-plastic behavior, aiming the assessment of residual stresses in quenched 4140 steel cylinders. The observed microstructure confirms quantitatively and qualitatively the previsions of the AC3 Software. The results of the modeling are compared with the residual stresses measurements made using X-Ray diffraction techniques. The finite element numerical simulation shows the existence of 350 MPa compressive residual stresses in the surface region and indicates that the most significant stresses are tangential.
Prediction of residual stresses in electron beam welded Ti-6Al-4V plates

Energy Technology Data Exchange (ETDEWEB)

Xu, Lianyong; Ge, Keke; Jing, Hongyang; Zhao, Lei; Lv, Xiaoqing [Tianjin Univ. (China); Han, Yongdian [Tianjin Univ. (China). Key Lab. of Advanced Joining Technology

2017-05-01

A thermo-metallurgical procedure based on the SYSWELD code was developed to predict welding temperature field, microstructure and residual stress in butt-welded Ti-6Al-4V plate taking into account phase transformation. The formation of martensite was confirmed by the CCT diagram and microstructure in the weld joint, which significantly affects the magnitude of residual stress. The hole drilling procedure was utilized to measure the values of residual stress at the top surface of the specimen, which are in well agreement with the numerical results. Both simulated and test results show that the magnitude and distribution of residual stress on the surface of the plate present a large gradient feature from the weld joint to the base metal. Moreover, the distribution law of residual stresses in the plate thickness was further analyzed for better understanding of its generation and evolution.
Effect of Applied Stress and Temperature on Residual Stresses Induced by Peening Surface Treatments in Alloy 600

Science.gov (United States)

Telang, A.; Gnäupel-Herold, T.; Gill, A.; Vasudevan, V. K.

2018-04-01

In this study, the effects of applied tensile stress and temperature on laser shock peening (LSP) and cavitation shotless peening (CSP)-induced compressive residual stresses were investigated using neutron and x-ray diffraction. Residual stresses on the surface, measured in situ, were lower than the applied stress in LSP- and CSP-treated Alloy 600 samples (2 mm thick). The residual stress averaged over the volume was similar to the applied stress. Compressive residual stresses on the surface and balancing tensile stresses in the interior relax differently due to hardening induced by LSP. Ex situ residual stress measurements, using XRD, show that residual stresses relaxed as the applied stress exceeded the yield strength of the LSP- and CSP-treated Alloy 600. Compressive residual stresses induced by CSP and LSP decreased by 15-25% in magnitude, respectively, on exposure to 250-450 °C for more than 500 h with 10-11% of relaxation occurring in the first few hours. Further, 80% of the compressive residual stresses induced by LSP and CSP treatments in Alloy 600 were retained even after long-term aging at 350 °C for 2400 h.
A Numerical Model for Prediction of Residual Stress Using Rayleigh Waves

International Nuclear Information System (INIS)

Yuan, Mao Dan; Kang, To; Kim, Hak Joon; Song, Sung Jin

2011-01-01

In this work, a numerical model is proposed for the relation between the magnitudes and the depth residual stress with the velocity of Rayleigh wave. Three cases, stress-free, uniform stress and layered stress, are investigated for the change tendency of the Rayleigh wave speed. Using the simulated signal with variation of residual stress magnitude and depth, investigation of the parameters for fitting residual stress and velocity change are performed. The speed change of Rayleigh wave shows a linear relation with the magnitude and an exponential relation with the depth of residual stress. The combination of these two effects could be used for the depth profile evaluation of the residual stress
Measurement of residual stress in quenched 1045 steel by the nanoindentation method

International Nuclear Information System (INIS)

Zhu Lina; Xu Binshi; Wang Haidou; Wang Chengbiao

2010-01-01

In this paper, the residual stress in quenched AISI 1045 steel was measured by a recently developed nanoindentation technique. Depth control mode was adopted to measure the residual stress. It was found that residual compressive stress was generated in the quenched steel. The material around nanoindents exhibits significant pile-up deformation. A new method was proposed to determine the real contact area for pile-up material on the basis of invariant pile-up morphology of the loaded or unloaded states. The results obtained by the new method were in good agreement with the residual stresses measured by the classical X-ray diffraction (XRD) method. - Research Highlights: → A new method was proposed to measure the real contact area for pile-up materials. → The real contact depth is defined as the sum of h max and the pile-up height h p . → The value of residual stress measured by the nanoindentation method was in good agreement with that by the XRD method.
Residual stresses in plastic random systems

NARCIS (Netherlands)

Alava, M.J.; Karttunen, M.E.J.; Niskanen, K.J.

1995-01-01

We show that yielding in elastic plastic materials creates residual stresses when local disorder is present. The intensity of these stresses grows with the external stress and degree of initial disorder. The one-dimensional model we employ also yields a discontinuous transition to perfect plasticity
Residual stress evaluation in brittle coatings using indentation technique combined with in-situ bending

International Nuclear Information System (INIS)

Futakawa, Masatoshi; Steinbrech, R.W.; Tanabe, Yuji; Hara, Toshiaki

2000-01-01

The indentation crack length approach was adopted and further elaborated to evaluate residual stress and toughness of the brittle coatings: two kinds of glass coatings on steel. The influence of the residual stress on indentation cracking was examined in as-received coating condition and by in-situ superimposing a counteracting tensile stress. For purpose of providing reference toughness values stress-free pieces of separated coating material have also been examined. Thus results of the two complementary sets of experiments were assumed to prove self-consistently toughness and residual stress data of the coating. In particular, the in-situ bending of specimen in combination with the indentation test allowed us to vary deliberately the residual stress situation in glass coating. Thus experiments which utilized the combination of bending test and micro-indentation were introduced as a method to provide unambiguous information about residual compressive stress. Toughness and residual compressive stress of glass coatings used in this study were 0.46-0.50 MPa·m 1/2 and 94-111 MPa, respectively. Furthermore, a thermoelastic calculation of the residual compressive stress was performed and it is found that the value of residual compressive stress at coating surface of specimen was 90-102 MPa. (author)

Residual stress measurements in thick structural weldments by means of neutron diffraction

International Nuclear Information System (INIS)

Ohms, C.; Youtsos, A.G.; Idsert, P. v.d.; Timke, T.

2000-01-01

Welding residual stresses in large structural components are a major concern with respect to their performance and lifetime. In large structures reasonable thermal stress relief treatment is usually impossible due to the component size. On the other hand, prediction of welding stresses by numerical modelling has not yet proven to be generally reliable, while the experimental determination of such stresses remains a demanding task. At the high flux reactor (HFR), Petten, a new residual stress diffractometer has been installed recently capable of handling of components up to 1000 kg - the large component neutron diffraction facility (LCNDF). It has facilitated residual stress measurements in two large welded components, of which results are presented here. The first component represents a bi-metallic weld in form of a pipe of 25 mm wall thickness. Three dimensional measurements of residual stress are discussed in detail. The second specimen is a 66 mm wall thickness austenitic steel nuclear piping weld. Results on relief of strain within the weld through post weld heat treatment (PWHT) are presented. Additionally results obtained earlier at former CRNL (CAN) on a section of a thick nuclear piping weld are presented in order to illustrate the variation in the reference lattice parameter trough the weld and the heat affected zone (HAZ). These results clearly show the necessity to determine the reference parameters for each location in all measurement directions by means of measurements in small coupons free of macro-stresses. (orig.)
Methods of measuring residual stresses in components

International Nuclear Information System (INIS)

Rossini, N.S.; Dassisti, M.; Benyounis, K.Y.; Olabi, A.G.

2012-01-01

Highlights: ► Defining the different methods of measuring residual stresses in manufactured components. ► Comprehensive study on the hole drilling, neutron diffraction and other techniques. ► Evaluating advantage and disadvantage of each method. ► Advising the reader with the appropriate method to use. -- Abstract: Residual stresses occur in many manufactured structures and components. Large number of investigations have been carried out to study this phenomenon and its effect on the mechanical characteristics of these components. Over the years, different methods have been developed to measure residual stress for different types of components in order to obtain reliable assessment. The various specific methods have evolved over several decades and their practical applications have greatly benefited from the development of complementary technologies, notably in material cutting, full-field deformation measurement techniques, numerical methods and computing power. These complementary technologies have stimulated advances not only in measurement accuracy and reliability, but also in range of application; much greater detail in residual stresses measurement is now available. This paper aims to classify the different residual stresses measurement methods and to provide an overview of some of the recent advances in this area to help researchers on selecting their techniques among destructive, semi destructive and non-destructive techniques depends on their application and the availabilities of those techniques. For each method scope, physical limitation, advantages and disadvantages are summarized. In the end this paper indicates some promising directions for future developments.
Measurement of residual stresses by the moire method

Science.gov (United States)

Sciammarella, C. A.; Albertazzi, A., Jr.

Three different applications of the moire method to the determination of residual stresses and strains are presented. The three applications take advantage of the property of ratings to record the changes of the surface they are printed on. One of the applications deals with thermal residual stresses, another with contact residual stress and the third one is a generalization of the blind hole technique. This last application is based on a computer assisted moire technique and on the generalization of the quasi-heterodyne techniques of fringe pattern analysis.
Effects of weld residual stresses on crack-opening area analysis of pipes for LBB applications

Energy Technology Data Exchange (ETDEWEB)

Dong, P.; Rahman, S.; Wilkowski, G. [and others

1997-04-01

This paper summarizes four different studies undertaken to evaluate the effects of weld residual stresses on the crack-opening behavior of a circumferential through-wall crack in the center of a girth weld. The effect of weld residual stress on the crack-opening-area and leak-rate analyses of a pipe is not well understood. There are no simple analyses to account for these effects, and, therefore, they are frequently neglected. The four studies involved the following efforts: (1) Full-field thermoplastic finite element residual stress analyses of a crack in the center of a girth weld, (2) A comparison of the crack-opening displacements from a full-field thermoplastic residual stress analysis with a crack-face pressure elastic stress analysis to determine the residual stress effects on the crack-opening displacement, (3) The effects of hydrostatic testing on the residual stresses and the resulting crack-opening displacement, and (4) The effect of residual stresses on crack-opening displacement with different normal operating stresses.
Effects of weld residual stresses on crack-opening area analysis of pipes for LBB applications

International Nuclear Information System (INIS)

Dong, P.; Rahman, S.; Wilkowski, G.

1997-01-01

This paper summarizes four different studies undertaken to evaluate the effects of weld residual stresses on the crack-opening behavior of a circumferential through-wall crack in the center of a girth weld. The effect of weld residual stress on the crack-opening-area and leak-rate analyses of a pipe is not well understood. There are no simple analyses to account for these effects, and, therefore, they are frequently neglected. The four studies involved the following efforts: (1) Full-field thermoplastic finite element residual stress analyses of a crack in the center of a girth weld, (2) A comparison of the crack-opening displacements from a full-field thermoplastic residual stress analysis with a crack-face pressure elastic stress analysis to determine the residual stress effects on the crack-opening displacement, (3) The effects of hydrostatic testing on the residual stresses and the resulting crack-opening displacement, and (4) The effect of residual stresses on crack-opening displacement with different normal operating stresses
Effect of processing conditions on residual stress distributions by bead-on-plate welding after surface machining

International Nuclear Information System (INIS)

Ihara, Ryohei; Mochizuki, Masahito

2014-01-01

Residual stress is important factor for stress corrosion cracking (SCC) that has been observed near the welded zone in nuclear power plants. Especially, surface residual stress is significant for SCC initiation. In the joining processes of pipes, butt welding is conducted after surface machining. Residual stress is generated by both processes, and residual stress distribution due to surface machining is varied by the subsequent butt welding. In previous paper, authors reported that residual stress distribution generated by bead on plate welding after surface machining has a local maximum residual stress near the weld metal. The local maximum residual stress shows approximately 900 MPa that exceeds the stress threshold for SCC initiation. Therefore, for the safety improvement of nuclear power plants, a study on the local maximum residual stress is important. In this study, the effect of surface machining and welding conditions on residual stress distribution generated by welding after surface machining was investigated. Surface machining using lathe machine and bead on plate welding with tungsten inert gas (TIG) arc under various conditions were conducted for plate specimens made of SUS316L. Then, residual stress distributions were measured by X-ray diffraction method (XRD). As a result, residual stress distributions have the local maximum residual stress near the weld metal in all specimens. The values of the local maximum residual stresses are almost the same. The location of the local maximum residual stress is varied by welding condition. It could be consider that the local maximum residual stress is generated by same generation mechanism as welding residual stress in surface machined layer that has high yield stress. (author)
Analysis of residual stress in subsurface layers after precision hard machining of forging tools

Directory of Open Access Journals (Sweden)

Czan Andrej

2018-01-01

Full Text Available This paper is focused on analysis of residual stress of functional surfaces and subsurface layers created by precision technologies of hard machining for progressive constructional materials of forging tools. Methods of experiments are oriented on monitoring of residual stress in surface which is created by hard turning (roughing and finishing operations. Subsequently these surfaces were etched in thin layers by electro-chemical polishing. The residual stress was monitored in each etched layer. The measuring was executed by portable X-ray diffractometer for detection of residual stress and structural phases. The results significantly indicate rise and distribution of residual stress in surface and subsurface layers and their impact on functional properties of surface integrity.
Neutron measurement of residual stresses in a used railway rail

International Nuclear Information System (INIS)

Webster, P.J.; Low, K.S.; Mills, G.; Webster, G.A.

1990-01-01

The high resolution neutron diffraction technique has been applied to determine, non-destructively, the residual stress distribution developed in the head of a railway rail after normal service. Measurements were made, using the neutron strain scanner at the Institute Laue Langevin, Grenoble, on a transverse slice of rail 12mm thick taken from a section of straight track. The rail head was scanned in the three principal orientations in a series of parallel traverses sufficiently close to enable a two-dimensional matrix of data to be accumulated and vertical, transverse and longitudinal residual stress contours to be drawn. The results demonstrate the effectiveness and unique characteristics of the neutron technique to determine nondestructively and continuously the residual stresses inside engineering components
Investigation into Variations of Welding Residual Stresses and Redistribution Behaviors for Different Repair Welding Widths

International Nuclear Information System (INIS)

Park, Chiyong; Lee, Hweesueng; Huh, Namsu

2014-01-01

In this study, we investigated the variations in welding residual stresses in dissimilar metal butt weld due to width of repair welding and re-distribution behaviors resulting from similar metal welding (SMW) and mechanical loading. To this end, detailed two-dimensional axi-symmetric finite element (FE) analyses were performed considering five different repair welding widths. Based on the FE results, we first evaluated the welding residual stress distributions in repair welding. We then investigated the re-distribution behaviors of the residual stresses due to SMW and mechanical loads. It is revealed that large tensile welding residual stresses take place in the inner surface and that its distribution is affected, provided repair welding width is larger than certain value. The welding residual stresses resulting from repair welding are remarkably reduced due to SMW and mechanical loading, regardless of the width of the repair welding
Controlling BWR pipe cracking by residual stress modification

International Nuclear Information System (INIS)

Gilman, J.D.; Giannuzzi, A.J.; Childs, W.J.

1983-01-01

Intergranular stress corrosion cracking may occur in the weld heat-affected zone of susceptible stainless steel materials which have been used in some boiling water reactor piping systems. One of the prerequisite conditions for stress corrosion attack is a high tensile stress in the exposed, locally sensitized material near the weld root. Several processes have been developed which can deter stress corrosion attack by altering the residual stress distributions near the welds to ensure that low stresses prevail in critical locations. These residual stress modification remedies and their qualification testing are described in this paper. (author)
Prediction of Weld Residual Stress of Narrow Gap Welds

International Nuclear Information System (INIS)

Yang, Jun Seog; Huh, Nam Su

2010-01-01

The conventional welding technique such as shield metal arc welding has been mostly applied to the piping system of the nuclear power plants. It is well known that this welding technique causes the overheating and welding defects due to the large groove angle of weld. On the other hand, the narrow gap welding(NGW) technique has many merits, for instance, the reduction of welding time, the shrinkage of weld and the small deformation of the weld due to the small groove angle and welding bead width comparing with the conventional welds. These characteristics of NGW affect the deformation behavior and the distribution of welding residual stress of NGW, thus it is believed that the residual stress results obtained from conventional welding procedure may not be applied to structural integrity evaluation of NGW. In this paper, the welding residual stress of NGW was predicted using the nonlinear finite element analysis to simulate the thermal and mechanical effects of the NGW. The present results can be used as the important information to perform the flaw evaluation and to improve the weld procedure of NGW
Specific features of the determination of residual stresses in materials by diffraction techniques

Science.gov (United States)

Gorkunov, E. S.; Zadvorkin, S. M.; Goruleva, L. S.

2017-12-01

Residual stresses arising in separate machine parts and structural components during production and use to a large extent govern their lifetime. In this connection, the development and improvement of nondestructive methods for the determination of residual stresses is an important task for nondestructive testing. Standards regulate only the determination of macroscopic stresses, and in practice these stresses are most often determined with the application of the sin2ψ method. This paper, using quenched structural steels as an example, compares the results of residual stress determination by the sin2ψ method with those obtained by the method based on the analysis of the diffraction line profile as dependent on the value of the irradiated volume. It is demonstrated that, as the irradiated volume decreases, the value of residual stresses determined by the sin2ψ method may vary considerably, up to the change of the sign. For a more complete characteristic of residual stresses it is proposed to use, besides the determination of macrostresses by the shift of the diffraction lines, the value of microscopic stresses calculated from the line profile analysis.
Residual stress analysis in carbon fiber-reinforced SiC ceramics

International Nuclear Information System (INIS)

Broda, M.

1998-01-01

Systematic residual stress analyses are reported, carried out in long-fiber reinforced SiC ceramics. The laminated C fiber /SiC matrix specimens used were prepared by polymer pyrolysis, and the structural component specimens used are industrial products. Various diffraction methods have been applied for non-destructive evaluation of residual stress fields, so as to completely detect the residual stresses and their distribution in the specimens. The residual stress fields at the surface (μm) have been measured using characteristic X-radiation and applying the sin 2 ψ method as well as the scatter vector method. For residual stress field analysis in the mass volume (cm), neutron diffraction has been applied. The stress fields in the fiber layers (approx. 250μm) have been measured as a function of their location within the laminated composite by using an energy-dispersive method and synchrotron radiation. By means of the systematic, process-accompanying residual stress and phase analyses, conclusions can be drawn as to possible approaches for optimization of fabrication parameters. (orig./CB) [de
Development of residual stress analysis procedure for fitness-for-service assessment of welded structure

International Nuclear Information System (INIS)

Kim, Jong Sung; Jin, Tae Eun; Dong, P.; Prager, M.

2003-01-01

In this study, a state of art review of existing residual stress analysis techniques and representative solutions is presented in order to develop the residual stress analysis procedure for Fitness-For-Service(FFS) assessment of welded structure. Critical issues associated with existing residual stress solutions and their treatments in performing FFS are discussed. It should be recognized that detailed residual stress evolution is an extremely complicated phenomenon that typically involves material-specific thermomechanical/metallurgical response, welding process physics, and structural interactions within a component being welded. As a result, computational procedures can vary significantly from highly complicated numerical techniques intended only to elucidate a small part of the process physics to cost-effective procedures that are deemed adequate for capturing some of the important features in a final residual stress distribution. Residual stress analysis procedure for FFS purposes belongs to the latter category. With this in mind, both residual stress analysis techniques and their adequacy for FFS are assessed based on both literature data and analyses performed in this investigation
Elastic/plastic analyses of advanced composites investigating the use of the compliant layer concept in reducing residual stresses resulting from processing

Science.gov (United States)

Arnold, Steven M.; Arya, Vinod K.; Melis, Matthew E.

1990-01-01

High residual stresses within intermetallic and metal matrix composite systems can develop upon cooling from the processing temperature to room temperature due to the coefficient of thermal expansion (CTE) mismatch between the fiber and matrix. As a result, within certain composite systems, radial, circumferential, and/or longitudinal cracks have been observed to form at the fiber-matrix interface. The compliant layer concept (insertion of a compensating interface material between the fiber and matrix) was proposed to reduce or eliminate the residual stress buildup during cooling and thus minimize cracking. The viability of the proposed compliant layer concept is investigated both elastically and elastoplastically. A detailed parametric study was conducted using a unit cell model consisting of three concentric cylinders to determine the required character (i.e., thickness and material properties) of the compliant layer as well as its applicability. The unknown compliant layer mechanical properties were expressed as ratios of the corresponding temperature dependent Ti-24Al-11Nb (a/o) matrix properties. The fiber properties taken were those corresponding to SCS-6 (SiC). Results indicate that the compliant layer can be used to reduce, if not eliminate, radial and circumferential residual stresses within the fiber and matrix and therefore also reduce or eliminate the radial cracking. However, with this decrease in in-plane stresses, one obtains an increase in longitudinal stress, thus potentially initiating longitudinal cracking. Guidelines are given for the selection of a specific compliant material, given a perfectly bonded system.
Residual stress measurement in a metal microdevice by micro Raman spectroscopy

International Nuclear Information System (INIS)

Song, Chang; Du, Liqun; Qi, Leijie; Li, Yu; Li, Xiaojun; Li, Yuanqi

2017-01-01

Large residual stress induced during the electroforming process cannot be ignored to fabricate reliable metal microdevices. Accurate measurement is the basis for studying the residual stress. Influenced by the topological feature size of micron scale in the metal microdevice, residual stress in it can hardly be measured by common methods. In this manuscript, a methodology is proposed to measure the residual stress in the metal microdevice using micro Raman spectroscopy (MRS). To estimate the residual stress in metal materials, micron sized β -SiC particles were mixed in the electroforming solution for codeposition. First, the calculated expression relating the Raman shifts to the induced biaxial stress for β -SiC was derived based on the theory of phonon deformation potentials and Hooke’s law. Corresponding micro electroforming experiments were performed and the residual stress in Ni–SiC composite layer was both measured by x-ray diffraction (XRD) and MRS methods. Then, the validity of the MRS measurements was verified by comparing with the residual stress measured by XRD method. The reliability of the MRS method was further validated by the statistical student’s t -test. The MRS measurements were found to have no systematic error in comparison with the XRD measurements, which confirm that the residual stresses measured by the MRS method are reliable. Besides that, the MRS method, by which the residual stress in a micro inertial switch was measured, has been confirmed to be a convincing experiment tool for estimating the residual stress in metal microdevice with micron order topological feature size. (paper)
Residual stress measurement in a metal microdevice by micro Raman spectroscopy

Science.gov (United States)

Song, Chang; Du, Liqun; Qi, Leijie; Li, Yu; Li, Xiaojun; Li, Yuanqi

2017-10-01

Large residual stress induced during the electroforming process cannot be ignored to fabricate reliable metal microdevices. Accurate measurement is the basis for studying the residual stress. Influenced by the topological feature size of micron scale in the metal microdevice, residual stress in it can hardly be measured by common methods. In this manuscript, a methodology is proposed to measure the residual stress in the metal microdevice using micro Raman spectroscopy (MRS). To estimate the residual stress in metal materials, micron sized β-SiC particles were mixed in the electroforming solution for codeposition. First, the calculated expression relating the Raman shifts to the induced biaxial stress for β-SiC was derived based on the theory of phonon deformation potentials and Hooke’s law. Corresponding micro electroforming experiments were performed and the residual stress in Ni-SiC composite layer was both measured by x-ray diffraction (XRD) and MRS methods. Then, the validity of the MRS measurements was verified by comparing with the residual stress measured by XRD method. The reliability of the MRS method was further validated by the statistical student’s t-test. The MRS measurements were found to have no systematic error in comparison with the XRD measurements, which confirm that the residual stresses measured by the MRS method are reliable. Besides that, the MRS method, by which the residual stress in a micro inertial switch was measured, has been confirmed to be a convincing experiment tool for estimating the residual stress in metal microdevice with micron order topological feature size.
Effects of the magnesium oxide thin films' microstructures on the residual stresses

Energy Technology Data Exchange (ETDEWEB)

He, Li-jun, E-mail: helijun4@126.com [The School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); The State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Wang, Li-yan [Electronic Information and Networking Research Institute, Collaborative Innovation Center for Information Communication Technology, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Chen, Wei-Zhong [The School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Liu, Xing-zhao [The State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2016-09-15

The MgO thin films are deposited at various inclined angles. The morphology investigated by scanning electron microscope (SEM) shows the MgO thin films deposited at high inclined angles have columnar grain. The relationships between full width high maximum (FWHM) of ω-scan, residual stresses and the inclined angles are studied. The results show the smallest FWHM of MgO (002) is 4.968°, the residual stress of MgO thin films is compressive stress, and the residual stress of MgO thin films deposited at the inclined angle of 55° is the smallest. So the microstructures of MgO thin films fabricated by the oblique angle deposition (OAD) technique effectively control the residual stresses. - Highlights: • MgO thin films are deposited by oblique angle deposition technique. • The FWHMs of MgO is the smallest at the inclined angle of 55°. • Residual stress of MgO is the smallest at the inclined angle of 55°.
Calculation method for residual stress analysis of filament-wound spherical pressure vessels

International Nuclear Information System (INIS)

Knight, C.E. Jr.

1976-01-01

Filament wound spherical pressure vessels may be produced with very high performance factors. These performance factors are a calculation of contained pressure times enclosed volume divided by structure weight. A number of parameters are important in determining the level of performance achieved. One of these is the residual stress state in the fabricated unit. A significant level of an unfavorable residual stress state could seriously impair the performance of the vessel. Residual stresses are of more concern for vessels with relatively thick walls and/or vessels constructed with the highly anisotropic graphite or aramid fibers. A method is established for measuring these stresses. A theoretical model of the composite structure is required. Data collection procedures and techniques are developed. The data are reduced by means of the model and result in the residual stress analysis. The analysis method can be used in process parameter studies to establish the best fabrication procedures
Relationship between ultrasonic Rayleigh waves and surface residual stress

International Nuclear Information System (INIS)

Adler, L.; Cook, K.V.; Dewey, B.R.; King, R.T.

1977-01-01

Local variations of Rayleigh (surface) circumferential ultrasonic wave velocity near a pipe-girth weld in large-diameter thin-wall type 316H stainless steel pipe were measured. The weldment was similar to those anticipated for the Liquid Metal Fast Breeder Reactor (LMFBR) piping systems. The residual stress distribution was estimated independently from shell theory for an elastic, infinite, thin shell with circumferential line loading. An upper bound on the magnitude of the residual stresses was estimated assuming the deformation of the shell was entirely elastic. The pattern of surface wave velocity variations matches the theoretical residual stress pattern closely. It is suggested that the monitoring of surface wave velocity variations might be used for characterizing residual stress patterns near critical welds in piping, aiding in design calculations, and for in-service monitoring of the state of stress of weldments

Residual stress improvement in multi-layer welded plates using water-shower cooling during welding process

International Nuclear Information System (INIS)

Yanagida, Nobuyoshi; Koide, Hiroo

2006-01-01

To reduce tensile residual stress in a welded region, we developed a new welding method that applies a water-shower behind the welding torch. When this method is applied to welding of austenitic stainless steel plates, cooling conditions mainly determine how much the residual stress can be reduced. To determine the conditions, we first used FEM to evaluate the effects of interpass temperature on the residual stress. And we found effective conditions for reducing tensile residual stress. To verify the validity of the conditions, specimens welded with or without water shower cooling were manufactured. Residual stresses of the specimens were experimentally measured. It was found that tensile residual stresses were generated on the surface of the welds and those were reduced in the case that the water-shower was applied. These measurement results agree well with the FEM analyses. It can therefore be concluded that the water-shower cooling during welding is appropriate for reducing tensile residual stress in austenitic stainless steel welding. (author)
Ultrasonic measurements on residual stress in autofrettged thick walled petroleum pipes

International Nuclear Information System (INIS)

Woias, G.; Mizera, J.

2008-01-01

optimal specimen length as 60 mm required beam time is for three slices measurements in depth of wall. This work is to compare the neutron stresses on ultrasound technique and FEM. Results of FEM modeling shows the axial compression zone in the inner side of the pipe. The residual stresses are growing while the pipe is in exploitation. Non-destructive method of measurements - ultrasonic - will be the best way of life time assessment and degradation monitoring. That's why the results obtained with other residual stresses measuring methods are significant. The measurements using neutron gauge are planned to be done on the inner surface of the pipe. According to the FEM model the dimensions of the sample to rule out any risk of residual stresses relaxation are described in inferences by FEM analysis. To assess residual stresses with 5% accuracy it is required to measure slice cut samples not less that two pipe's thickness length - 60 cm. Three samples were prepared to be measured: 1) New pipe after autofrettaging [Np]; 2) Pipe after exploitation from the upper part of the reactor - heating zone [11/1]; 3) Pipe from lower part - cooling zone [75]. In the first part of the experiment, the pipe no [11/1] has been measured for axial and hoop stresses. The pipe [Np] was measured for axial stresses. The aim of these measurements will be measuring hoop residual stress on a non-used pipe after autofrettaging [Np] as well as hoop and axial stresses in a pipe taken from the lower part of the reactor - the cooling zone. (author)
Residual stress effects on the K parameter of the fracture mechanics

International Nuclear Information System (INIS)

Soares, Maria da Conceiccao B. Vieira; Andrade, Arnaldo H. Paes de

1996-01-01

Compressive residual stresses are beneficial and improve resistance to fracture and crack growth. Residual stresses can be introduced in fabricated components by a variety of means and a number of methods such as laser surface treatment, cold expanded hole, and shot peening. Neutrons diffraction measurements of residual stress were performed at a pulsed neutron source (ISIS, Didcot, UK), on shot peened plates of nickel base superalloy Udimet 720 and titanium alloy IMI 834. The stress intensity factor (K) of residual stress was evaluated by finite element modeling and weight function method. Finite element modeling of a 2D plate with a single edge-notch was applied and, due to symmetry only half of the plate was actually modeled. The stress intensity factor (K) was evaluated for both case of remote tension stress and residual stress. Crack surface overlapping, which is physically unacceptable, was noted for small cracks under residual and boundary lading. Overlap correction was proposed and applied in order to obtain reliable values for (K). (author)
Stress-Softening and Residual Strain Effects in Suture Materials

Directory of Open Access Journals (Sweden)

Alex Elías-Zúñiga

2013-01-01

Full Text Available This work focuses on the experimental characterization of suture material samples of MonoPlus, Monosyn, polyglycolic acid, polydioxanone 2–0, polydioxanone 4–0, poly(glycolide-co-epsilon-caprolactone, nylon, and polypropylene when subjected to cyclic loading and unloading conditions. It is found that all tested suture materials exhibit stress-softening and residual strain effects related to the microstructural material damage upon deformation from the natural, undistorted state of the virgin suture material. To predict experimental observations, a new constitutive material model that takes into account stress-softening and residual strain effects is developed. The basis of this model is the inclusion of a phenomenological nonmonotonous softening function that depends on the strain intensity between loading and unloading cycles. The theory is illustrated by modifying the non-Gaussian average-stretch, full-network model to capture stress-softening and residual strains by using pseudoelasticity concepts. It is shown that results obtained from theoretical simulations compare well with suture material experimental data.
On the evaluation of residual stress and mechanical properties of FeCrBSi coatings by nanoindentation

International Nuclear Information System (INIS)

Zhu Lina; Xu Binshi; Wang Haidou; Wang Chengbiao

2012-01-01

Highlights: ► Ni/Al coating can reduce the mismatch degree between the coating and substrate. ► No obvious pile-up is observed for the nanoindents of the FeCrBSi coating. ► The higher the tensile residual stress, the lower the hardness and elastic modulus. - Abstract: In this paper, the residual stress in the plasma-sprayed FeCrBSi coating was determined by nanoindentation and X-ray diffraction (XRD). The XRD results showed that tensile residual stress was generated in the FeCrBSi coating, and the through-thickness values range between 40 MPa and 112 MPa. The residual stress measured by nanoindentation is 753 MPa. The difference between the XRD and nanoindentation results was discussed. It is found that the factors limiting the nanoindentation measurement of residual stress include the ‘sink-in’ deformation around the indenter, the roughness of the FeCrBSi coating, and the use of reference sample without residual stress. The above three factors lead to the over-prediction of residual stress by nanoindentation.
Estimation of residual stress distribution for pressurizer nozzle of Kori nuclear power plant considering safe end

Energy Technology Data Exchange (ETDEWEB)

Song, Tae Kwang; Bae, Hong Yeol; Chun, Yun Bae; Oh, Chang Young; Kim, Yun Jae [Korea University, Seoul (Korea, Republic of); Lee, Kyoung Soo; Park, Chi Yong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

2008-08-15

In nuclear power plants, ferritic low alloy steel nozzle was connected with austenitic stainless steel piping system through alloy 82/182 butt weld. Accurate estimation of residual stress for weldment is important in the sense that alloy 82/182 is susceptible to stress corrosion cracking. There are many results which predict residual stress distribution for alloy 82/182 weld between nozzle and pipe. However, nozzle and piping system usually connected through safe end which has short length. In this paper, residual stress distribution for pressurizer nozzle of Kori nuclear power plant was predicted using FE analysis, which considered safe end. As a result, existing residual stress profile was redistributed and residual stress of inner surface was decreased specially. It means that safe end should be considered to reduce conservatism when estimating the piping system.
Neutron diffraction measurements of residual stress in additively manufactured stainless steel

International Nuclear Information System (INIS)

Brown, D.W.; Bernardin, J.D.; Carpenter, J.S.; Clausen, B.; Spernjak, D.; Thompson, J.M.

2016-01-01

Charpy test specimens were additively manufactured (AM) on a single stainless steel plate from a 17–4 class stainless steel using a powder-bed, laser melting technique on an EOS M280 direct metal laser sintering (DMLS) machine. Cross-hatched mesh support structures for the Charpy test specimens were varied in strut width and density to parametrically study their influence on the build stability and accuracy as the DMLS process has been known to generate parts with large amounts of residual stress. Neutron diffraction was used to profile the residual stresses in several of the AM samples before and after the samples were removed from the support structure for the purpose of determining residual stresses. The residual stresses were found to depend very little on the properties of the support structure over the limited range studied here. The largest stress component was in the long direction of each of the samples studied and was roughly 2/3 of the yield stress of the material. The stress field was altered considerably when the specimen was removed from the support structure. It was noted in this study that a single Charpy specimen developed a significant tear between the growth plate and support structure. The presence of the tear in the support structure strongly affected the observed stress field: the asymmetric tear resulted in a significantly asymmetric stress field that propagated through removal of the sample from the base plate. The altered final residual stress state of the sample as well as its observed final shape indicates that the tear initiated during the build and developed without disrupting the fabrication process, suggesting a need for in-situ monitoring.
Neutron diffraction measurements of residual stress in additively manufactured stainless steel

Energy Technology Data Exchange (ETDEWEB)

Brown, D.W.; Bernardin, J.D.; Carpenter, J.S.; Clausen, B.; Spernjak, D.; Thompson, J.M.

2016-12-15

Charpy test specimens were additively manufactured (AM) on a single stainless steel plate from a 17–4 class stainless steel using a powder-bed, laser melting technique on an EOS M280 direct metal laser sintering (DMLS) machine. Cross-hatched mesh support structures for the Charpy test specimens were varied in strut width and density to parametrically study their influence on the build stability and accuracy as the DMLS process has been known to generate parts with large amounts of residual stress. Neutron diffraction was used to profile the residual stresses in several of the AM samples before and after the samples were removed from the support structure for the purpose of determining residual stresses. The residual stresses were found to depend very little on the properties of the support structure over the limited range studied here. The largest stress component was in the long direction of each of the samples studied and was roughly 2/3 of the yield stress of the material. The stress field was altered considerably when the specimen was removed from the support structure. It was noted in this study that a single Charpy specimen developed a significant tear between the growth plate and support structure. The presence of the tear in the support structure strongly affected the observed stress field: the asymmetric tear resulted in a significantly asymmetric stress field that propagated through removal of the sample from the base plate. The altered final residual stress state of the sample as well as its observed final shape indicates that the tear initiated during the build and developed without disrupting the fabrication process, suggesting a need for in-situ monitoring.
Residual stresses associated with welds in austenitic steel

International Nuclear Information System (INIS)

Fidler, R.

1978-01-01

Two exploratory welds have been made with AISI 316 austenitic steel and Armex GT electrodes by the manual metal-arc process, and residual stress measurements made in the as-welded condition and after various periods of stress relief. The results show that substantial stress relief occurs at temperatures of 850 0 and 750 0 C after 1 hr, but is not complete. The stress distributions are compared with those obtained from ferritic welds and the effect of differences in thermal expansion coefficients is examined using finite element analysis. (author)
Study on the residual stress relaxation in girth-welded steel pipes under bending load using diffraction methods

International Nuclear Information System (INIS)

Hempel, Nico; Nitschke-Pagel, Thomas; Dilger, Klaus

2017-01-01

This research is dedicated to the experimental investigation of the residual stress relaxation in girth-welded pipes due to quasi-static bending loads. Ferritic-pearlitic steel pipes are welded with two passes, resulting in a characteristic residual stress state with high tensile residual stresses at the weld root. Also, four-point bending is applied to generate axial load stress causing changes in the residual stress state. These are determined both on the outer and inner surfaces of the pipes, as well as in the pipe wall, using X-ray and neutron diffraction. Focusing on the effect of tensile load stress, it is revealed that not only the tensile residual stresses are reduced due to exceeding the yield stress, but also the compressive residual stresses for equilibrium reasons. Furthermore, residual stress relaxation occurs both parallel and perpendicular to the applied load stress.
Residual stress evaluation and curvature behavior of aluminium 7050 peen forming processed

International Nuclear Information System (INIS)

Oliveira, R.R. de; Lima, N.B.; Braga, A.P.V.; Goncalves, M.

2010-01-01

Shot peening is a superficial cold work process used to increase the fatigue life evaluated by residual stress measurements. The peen forming process is a variant of the shot peening process, where a curvature in the plate is obtained by the compression of the grains near to the surface. In this paper, the influence of the parameters such as: pressure of shot, ball shot size and thickness of aluminum 7050 samples with respect to residual stress profile and resulting arc height was studied. The evaluation of the residual stress profile was obtained by sin 2 Ψ method. (author)
Residual stress analysis for engineering applications by means of neutron diffraction

International Nuclear Information System (INIS)

Gnaeupel-Herold, T.; Brand, P.C.; Prask, H.J.

1999-01-01

Residual stresses originate from spatial differences in plastic deformation, temperature, or phase distribution, introduced by manufacturing processes or during service. Engineering parts and materials experience mechanical, thermal, and chemical loads during their service, and most of these loads introduce stresses that are superimposed on the already existing residual stresses. Residual stresses can therefore limit or improve life and strength of engineering parts; knowledge and understanding of these stresses is therefore critical for optimizing strength and durability. The economic and scientific importance of neutron diffraction residual stress analysis has led to an increasing number of suitable instruments worldwide. All of the major sources due in the next several years will have instruments for the sole purpose of performing residual stress and texture measurements. Recently, a dedicated, state-of-the-art diffractometer has been installed at the National Institute of Standards and Technology reactor. It has been used for a variety of measurements on basic and engineering stress problems. Among the most prominent examples that have been investigated in collaboration with industrial and academic partners are residual stresses in rails, weldments, and plasma-sprayed coatings
A comparison of residual stresses in built-up steel beams using hole-drilling method

International Nuclear Information System (INIS)

Nawafleh, M. A.; Hunaiti, Y. M.; Younes, R. M.

2009-01-01

Residual stresses have a significant effect on the stability resistance of metal building systems. An experimental program was conducted to measure these stresses in built-up steel beams using incremental hole-drilling method. The experimental results reveal that the predicted residual stress type of pattern for built-up I-sections with fillet welds on one side of the web is not the same as the pattern of residual stresses in built-up I-sections with fillet welds on both sides of the web
Stability of machining induced residual stresses in Inconel 718 under quasi-static loading at room temperature

International Nuclear Information System (INIS)

Madariaga, A.; Esnaola, J.A.; Arrazola, P.J.; Ruiz-Hervias, J.; Muñoz, P.; Ostolaza, K.

2015-01-01

Tensile residual stresses are very often generated on the surface when machining nickel alloys. In order to determine their influence on the final mechanical behaviour of the component residual stress stability should be considered. In the present work the evolution of surface residual stresses induced by machining in Inconel 718 under static loading at room temperature was studied experimentally and numerically. An Inconel 718 disc was face turned employing industrial working conditions and specimens for tensile tests were extracted from the disc. Surface residual stresses were measured by X-ray diffraction for initial state and after applying different loads over the material's yield stress. Then, a finite element model based on the surface–core approach was fitted to experimental results and the study was extended to analyse the influence of load level, degree of work-hardening and initial surface conditions. For the studied case, initial tensile surface residual stress (776 MPa) became even more tensile when applying loads higher than the material yield stress, but a shift was observed at the highest applied load (1350 MPa) and initial residual stress was relaxed about 170 MPa. This particular behaviour is associated to the modified stress–strain properties of the machined affected surface layer which was strongly work-hardened. Moreover, if the work-hardened properties are not considered in the finite element model results differ substantially from experiments. Surface residual stress stability also depends on the initial surface residual stress, but the degree of work-hardening induced by the machining process must be considered as well. If the difference between the yield stress of the surface and the yield stress of the core is lower than the initial surface residual stress, the surface begins yielding first and consequently the surface residual stress is decreased. In contrast, if the difference between the yield stress of the surface and the
Stability of machining induced residual stresses in Inconel 718 under quasi-static loading at room temperature

Energy Technology Data Exchange (ETDEWEB)

Madariaga, A., E-mail: amadariaga@mondragon.edu [Mechanical and Industrial Production Department, Faculty of Engineering, Mondragon Unibertsitatea, Loramendi 4, Mondragon 20500 Gipuzkoa (Spain); Esnaola, J.A.; Arrazola, P.J. [Mechanical and Industrial Production Department, Faculty of Engineering, Mondragon Unibertsitatea, Loramendi 4, Mondragon 20500 Gipuzkoa (Spain); Ruiz-Hervias, J.; Muñoz, P. [Departamento Ciencia de Materiales, ETSI Caminos, Universidad Politécnica de Madrid, c/Profesor Aranguren s/n, Madrid 28040 (Spain); Ostolaza, K. [Materials and Processes Technology Department, ITP S.A., Parque Tecnológico, Edificio 300, 48170 Zamudio (Spain)

2015-01-03

Tensile residual stresses are very often generated on the surface when machining nickel alloys. In order to determine their influence on the final mechanical behaviour of the component residual stress stability should be considered. In the present work the evolution of surface residual stresses induced by machining in Inconel 718 under static loading at room temperature was studied experimentally and numerically. An Inconel 718 disc was face turned employing industrial working conditions and specimens for tensile tests were extracted from the disc. Surface residual stresses were measured by X-ray diffraction for initial state and after applying different loads over the material's yield stress. Then, a finite element model based on the surface–core approach was fitted to experimental results and the study was extended to analyse the influence of load level, degree of work-hardening and initial surface conditions. For the studied case, initial tensile surface residual stress (776 MPa) became even more tensile when applying loads higher than the material yield stress, but a shift was observed at the highest applied load (1350 MPa) and initial residual stress was relaxed about 170 MPa. This particular behaviour is associated to the modified stress–strain properties of the machined affected surface layer which was strongly work-hardened. Moreover, if the work-hardened properties are not considered in the finite element model results differ substantially from experiments. Surface residual stress stability also depends on the initial surface residual stress, but the degree of work-hardening induced by the machining process must be considered as well. If the difference between the yield stress of the surface and the yield stress of the core is lower than the initial surface residual stress, the surface begins yielding first and consequently the surface residual stress is decreased. In contrast, if the difference between the yield stress of the surface and the
A primary simulation for residual stress neutron diffractometer

International Nuclear Information System (INIS)

Wang Shuying; Liu Lijuan; Sun Liangwei

2012-01-01

At present, neutron diffraction method is the unique and nondestructive method that can directly measure the residual stress distribution in deep materials and engineering components. It has an important application in engineering. A simulation of the flux at the position of the sample table was reported, and the resolution of the residual stress instrument was computed at the same time. The effect of the parameters of the second collimator on the flux at the sample position and the resolution of the instrument have been analyzed. The result indicated that the second collimator empress much on the neutron flux and the instrument resolution is well when the sample's diffraction angle is less than 120°. (authors)
Features of residual stresses in duplex stainless steel butt welds

Science.gov (United States)

Um, Tae-Hwan; Lee, Chin-Hyung; Chang, Kyong-Ho; Nguyen Van Do, Vuong

2018-04-01

Duplex stainless steel finds increasing use as an alternative to austenitic stainless steel, particularly where chloride or sulphide stress corrosion cracking is of primary concern, due to the excellent combination of strength and corrosion resistance. During welding, duplex stainless steel does not create the same magnitude or distribution of weld-induced residual stresses as those in welded austenitic stainless steel due to the different physical and mechanical properties between them. In this work, an experimental study on the residual stresses in butt-welded duplex stainless steel is performed utilizing the layering technique to investigate the characteristics of residual stresses in the weldment. Three-dimensional thermos-mechanical-metallurgical finite element analysis is also performed to confirm the residual stress measurements.
Prediction of three-dimensional residual stresses at localised indentations in pipes

International Nuclear Information System (INIS)

Hyde, T.H.; Luo, R.; Becker, A.A.

2012-01-01

Residual stresses are investigated using Finite Element (FE) analyses at localised indentations in pipes with and without internal pressures due to reverse plasticity caused by springback of the surrounding material after removal of the indenter. The indentation loading is applied via rigid 3D short indenters. The effects of the residual indentation depth, internal pressure, indenter size and different material properties on the residual stresses for different pipes have been investigated by carrying out parametric sensitivity studies. In order to predict the residual stresses, empirical formulations have been developed, which show a good correlation with the FE for residual stresses for pipes with diameter to thickness ratios of 35–72. - Highlights: ► A comprehensive elastic–plastic FE analysis of residual stresses caused by localised pipe indentations is presented. ► The effects of residual indentation depth, internal pressure, indenter size and material properties have been studied. ► Empirical formulations have been developed, which show a good correlation with the FE for residual stresses for pipes with diameter to thickness ratios of 35–72.
Two-step method to evaluate equibiaxial residual stress of metal surface based on micro-indentation tests

International Nuclear Information System (INIS)

Nishikawa, Masaaki; Soyama, Hitoshi

2011-01-01

Highlights: → The sensitivity to residual stress was improved by selecting the depth parameter. → Residual stress could be obtained while determining the effect of unknown parameters. → The estimated residual stress agreed well with those of X-ray diffraction. -- Abstract: The present study proposed a method to evaluate the equibiaxial compressive residual stress of a metal surface by means of a depth-sensing indentation method using a spherical indenter. Inverse analysis using the elastic-plastic finite-element model for an indentation test was established to evaluate residual stress from the indentation load-depth curve. The proposed inverse analysis utilizes two indentation test results for a reference specimen whose residual stress is already known and for a target specimen whose residual stress is unknown, in order to exclude the effect of other unknown mechanical properties, such as Young's modulus and yield stress. Residual stress estimated by using the indentation method is almost identical to that measured by X-ray diffraction for indentation loads of 0.49-0.98 N. Therefore, it can be concluded that the proposed method can effectively evaluate residual stress on metal surface.
Reduction method for residual stress of welded joint using random vibration

International Nuclear Information System (INIS)

Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro

2005-01-01

Welded joints are used for construction of many structures. Residual stress is induced near the bead caused by locally given heat. Tensile residual stress on the surface may reduce fatigue strength. In this paper, a new method for reduction of residual stress using vibration during welding is proposed. As vibrational load, random vibration, white noise and filtered white noise are used. Two thin plates are butt-welded. Residual stress is measured with a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. It is concluded that tensile residual stress near the bead is reduced by using random vibration during welding

Fatigue life estimation considering welding residual stress and hot-spot stress of welded components

International Nuclear Information System (INIS)

Han, S. H.; Lee, T. K.; Shin, B. C.

2002-01-01

The fatigue life of welded joints is sensitive to welding residual stress and complexity of their geometric shapes. To predict the fatigue life more reasonably, the effects of welding residual stress and its relaxation have to be considered quantitatively which are equivalent to mean stress by external loads. The hot-spot stress concept should be also adopted which can be reduce the dependence of fatigue strengths for various welding details. Considering the factors mentioned above, a fatigue life prediction model using the modified Goodman's diagram was proposed. In this model, an equivalent stress was introduced which are composed of the mean stress based on the hot-spot stress concept and the relaxed welding residual stress. From the verification of the proposed model to real welding details, it is confirmed that this model can be applied to predict reasonably their fatigue lives
Simplified method of calculating residual stress in circumferential welding of piping

International Nuclear Information System (INIS)

Umemoto, Tadahiro

1984-01-01

Many circumferential joints of piping are used in as-welded state, but in these welded joints, the residual stress as high as the yield stress of materials arises, and causes to accelerate stress corrosion cracking and corrosion fatigue. The experiment or the finite element method to clarify welding residual stress requires much time and labor, and is expensive, therefore, the author proposed the simplified method of calculation. The heating and cooling process of welding is very complex, and cannot be modeled as it is, therefore, it was assumed that in multiple layer welding, the welding condition of the last layer determines the residual stress, that material constants are invariable regardless of temperature, that the temperature distribution and residual stress are axisymmetric, and that there is repeated stress-strain relation in the vicinity of welded parts. The temperature distribution at the time of welding, thermal stress and welding residual stress are analyzed, and the material constants used for the calculation of residual stress are given. As the example of calculation, the effect of welding heat input and materials is shown. The extension of the method to a thick-walled pipe is discussed. (Kako, I.)
Sensitivity Analysis for Residual Stress on DVI (Direct Vessel Injection) Nozzle Welded Joint

International Nuclear Information System (INIS)

Noh, Byeong Wook; Chung, Sung Ho; Lee, Jung Hun; Kim, Oak Sug

2008-01-01

Generally, any welding process produces high compressive or tensile residual stresses in the heat affected zone depending on the method, shape and procedures of the weldment. In particular, the tensile residual stresses have a considerable effect on the material strength, fatigue strength and corrosion cracking. For this reason, it is important that some knowledge of the internal stress state be deduced either from measurements or from modeling predictions. In this study, the residual stresses after a multi-pass welding process for DVI nozzle welding joint were evaluated by a numerical simulation method. The welding joint considered three weld joint angles of 40 deg., 6 deg. and 2 deg. Computations were made using a 2-D finite element model based on the simulation of cooling from the heat treatment temperature to room temperature with two cooling conditions at the inside surface. In these results, it is shown that the residual stress increased at the inner surface, when water cooling was applied to the inner surface, and axial compressive residual stress increased at the inner surface when the joint angle was decreased. (authors)
Sensitivity Analysis for Residual Stress on DVI (Direct Vessel Injection) Nozzle Welded Joint

Energy Technology Data Exchange (ETDEWEB)

Noh, Byeong Wook; Chung, Sung Ho; Lee, Jung Hun; Kim, Oak Sug [DOOSAN Heavy Industries and Construction Co. LTD, Reactor Design Team, 555 Guygok-dong Changwon (Korea, Republic of)

2008-07-01

Generally, any welding process produces high compressive or tensile residual stresses in the heat affected zone depending on the method, shape and procedures of the weldment. In particular, the tensile residual stresses have a considerable effect on the material strength, fatigue strength and corrosion cracking. For this reason, it is important that some knowledge of the internal stress state be deduced either from measurements or from modeling predictions. In this study, the residual stresses after a multi-pass welding process for DVI nozzle welding joint were evaluated by a numerical simulation method. The welding joint considered three weld joint angles of 40 deg., 6 deg. and 2 deg. Computations were made using a 2-D finite element model based on the simulation of cooling from the heat treatment temperature to room temperature with two cooling conditions at the inside surface. In these results, it is shown that the residual stress increased at the inner surface, when water cooling was applied to the inner surface, and axial compressive residual stress increased at the inner surface when the joint angle was decreased. (authors)
Non-destructive measurement of residual stresses in U-0.8 wt.% Ti by neutron diffraction

International Nuclear Information System (INIS)

Salinas-Rodriguez, A.; Root, J.H.; Holden, T.M.; Macewen, S.R.; Ludtka, G.M.

1990-01-01

The macroscopic residual stress distribution in γ-quenched and stress levelled U-0.8wt% Ti alloy tubes was studied using neutron diffraction techniques. Residual strains were evaluated from the difference in d-spacings measured in the tubes and in small reference samples machined from each tube. Residual stresses were calculated with the isotropic bulk value of the elastic constraints for polycrystalline α-U. Quenching from the γ field resulted in a nearly equi-biaxial stress state at every point across the wall thickness of the tube. The magnitude of the radial stress was very small compared with that of the axial and hoop stresses which were compressive at the surfaces and tensile in the interior. Stress levelling relieved almost completely the hoop residual stress without affecting the radial stress. The axial residual stress becomes tensile through the wall thickness and remains constant at about 20% of its magnitude in the as-quenched condition
Fatigue life evaluation based on welding residual stress relaxation and notch strain approach for cruciform welded joint

International Nuclear Information System (INIS)

Han, Jeong Woo; Han, Seung Ho; Shin, Byung Chun; Kim, Jae Hoon

2003-01-01

The fatigue strength of welded joint is influenced by the welding residual stress which is relaxed depending on local stress distributed in vicinity of stress raisers, eg. under cut, overlap and blow hole. To evaluate its fatigue life the geometry of the stress raisers and the welding residual stress should be taken into account. The several methods based on notch strain approach have been proposed in order to consider the two factors above mentioned. These methods, however, have shown considerable differences between analytical and experimental results. It is due to the fact that the amount of the relaxed welding residual stress evaluated by the cyclic stress-strain relationship do not correspond with that occurred in reality. In this paper the residual stress relaxation model based on experimental results was used in order to reduce the discrepancy of the estimated amount of the relaxed welding residual stress. Under an assumption of the superimposition of the relaxed welding residual stress and the local stress, a modified notch strain approach was proposed and verified to the cruciform welded joint
Residual Stresses In 3013 Containers

International Nuclear Information System (INIS)

Mickalonis, J.; Dunn, K.

2009-01-01

The DOE Complex is packaging plutonium-bearing materials for storage and eventual disposition or disposal. The materials are handled according to the DOE-STD-3013 which outlines general requirements for stabilization, packaging and long-term storage. The storage vessels for the plutonium-bearing materials are termed 3013 containers. Stress corrosion cracking has been identified as a potential container degradation mode and this work determined that the residual stresses in the containers are sufficient to support such cracking. Sections of the 3013 outer, inner, and convenience containers, in both the as-fabricated condition and the closure welded condition, were evaluated per ASTM standard G-36. The standard requires exposure to a boiling magnesium chloride solution, which is an aggressive testing solution. Tests in a less aggressive 40% calcium chloride solution were also conducted. These tests were used to reveal the relative stress corrosion cracking susceptibility of the as fabricated 3013 containers. Significant cracking was observed in all containers in areas near welds and transitions in the container diameter. Stress corrosion cracks developed in both the lid and the body of gas tungsten arc welded and laser closure welded containers. The development of stress corrosion cracks in the as-fabricated and in the closure welded container samples demonstrates that the residual stresses in the 3013 containers are sufficient to support stress corrosion cracking if the environmental conditions inside the containers do not preclude the cracking process.
Residual stresses evaluation in a gas-pipeline crossing

Energy Technology Data Exchange (ETDEWEB)

Fonseca, Maria Cindra [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Almeida, Manoel Messias [COMPAGAS, Curitiba, PR (Brazil); Rebello, Joao Marcos Alcoforado [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Souza Filho, Byron Goncalves de [PETROBRAS, Rio de Janeiro, RJ (Brazil)

2009-07-01

The X-rays diffraction technique is a well established and effectiveness method in the determination of the residual and applied stresses in fine grained crystalline materials. It allows to characterize and to quantify the magnitude and direction of the existing surface stresses in the studied point of the material. The objective of this work is the evaluation of the surface stresses in a 10 in diameter Natural Gas Distribution Pipeline manufactured from API 5 L Gr B steel of COMPAGAS company, in a crossing with a Natural Gas Transportation Pipeline, in Araucaria-PR. This kind of evaluation is important to establish weather you have to perform a repositioning of one of the pipeline or not. The measurements had been made in two transversal sections of the pipe, the one upstream (170 mm of the external wall of the pipeline) and another one downstream (840 mm of the external wall of the pipeline). Each transversal section measurements where carried out in 3 points: 9 hours, 12 hours and 3 hours. In each measured point of the pipe surface, the longitudinal and transversal stresses had been measured. The magnitude of the surface residual stresses in the pipe varied of +180 MPa at the -210 MPa. The residual stress state on the surface of the points 12 hours region is characterized by tensile stresses and by compressive stresses in the points of 3 and 9 hours region. The surface residual stresses in gas-pipeline have been measured using X-ray diffraction method, by double exposure technique, using a portable apparatus, with Cr-K-alpha radiation. (author)
Residual stress reduction in the penetration nozzle weld joint by overlay welding

International Nuclear Information System (INIS)

Jiang, Wenchun; Luo, Yun; Wang, B.Y.; Tu, S.T.; Gong, J.M.

2014-01-01

Highlights: • Residual stress reduction in penetration weld nozzle by overlay welding was studied. • The overlay weld can decrease the residual stress in the weld root. • Long overlay welding is proposed in the actual welding. • Overlay weld to decrease residual stress is more suitable for thin nozzle. - Abstract: Stress corrosion cracking (SCC) in the penetration nozzle weld joint endangers the structural reliability of pressure vessels in nuclear and chemical industries. How to decrease the residual stress is very critical to ensure the structure integrity. In this paper, a new method, which uses overlay welding on the inner surface of nozzle, is proposed to decrease the residual stresses in the penetration joint. Finite element simulation is used to study the change of weld residual stresses before and after overlay welding. It reveals that this method can mainly decrease the residual stress in the weld root. Before overlay welding, large tensile residual stresses are generated in the weld root. After overlay weld, the tensile hoop stress in weld root has been decreased about 45%, and the radial stress has been decreased to compressive stress, which is helpful to decrease the susceptibility to SCC. With the increase of overlay welding length, the residual stress in weld root has been greatly decreased, and thus the long overlay welding is proposed in the actual welding. It also finds that this method is more suitable for thin nozzle rather than thick nozzle
Residual stresses associated with the hydraulic expansion of steam generator tubing into tubesheets

International Nuclear Information System (INIS)

Middlebrooks, W.B.; Harrod, D.L.; Gold, R.E.

1993-01-01

Various methods are being used to expand heat transfer tubes into the thick tubesheets of nuclear steam generators. The residual stresses in the as-expanded tubes and methods for reducing these stresses are important because of the role which residual stresses play in stress corrosion cracking and stress assisted corrosion of the tubing. Of the various expansion processes, the hydraulic expansion process is most amenable to analytical study. This paper presents results on the residual stresses and strains in hydraulically expanded tubes and the tubesheet as computed by two different finite element codes with three different finite element models and by a theoretical incremental analysis method. The calculations include a sensitivity analysis to assess the effects of the expansion variables and the effect of stress relief heat treatments. (orig.)
Evaluation of residual stresses for the multipass welds of 316L stainless steel pipe

International Nuclear Information System (INIS)

Kim, S. H.; Joo, Y. S.; Lee, J. H.

2003-01-01

It is necessary to evaluate the influence of the residual stress and distortion in the design and fabrication of welded structure and the sound welded structure can be maintained by this consideration. Multipass welds of the 316L stainless steel have been widely employed in the pipes of Liquid Metal Reactor. In this study, the residual stresses in the 316L stainless steel pipe welds were calculated by the finite element method using ANSYS code. Also, the residual stresses both on the surface and in the interior of the thickness were measured by HRPD(High Resolution Powder Diffractometer) instrumented in HANARO Reactor. The residual stresses were measured for each 18 points in small(t/d=0.075) and large pipe specimens (t/d=0.034). The experimental and calculated results were compared and the characteristics of the distribution of the residual stress discussed
Measurements of three dimensional residual stress distribution on laser irradiated spot

International Nuclear Information System (INIS)

Tanaka, Hirotomo; Akita, Koichi; Ohya, Shin-ichi; Sano, Yuji; Naito, Hideki

2004-01-01

Three dimensional residual stress distributions on laser irradiated spots were measured using synchrotron radiation to study the basic mechanism of laser peening. A water-immersed sample of high tensile strength steel was irradiated with Q-switched and frequency-doubled Nd:YAG laser. The residual stress depth profile of the sample was obtained by alternately repeating the measurement and surface layer removal by electrolytic polishing. Tensile residual stresses were observed on the surface of all irradiated spots, whereas residual stress changed to compressive just beneath the surface. The depth of compressive residual stress imparted by laser irradiation and plastic deformation zone increased with increasing the number of laser pulses irradiated on the same spot. (author)
Residual stress measurement of PMMA by combining drilling-hole with digital speckle correlation method

Science.gov (United States)

Yao, X. F.; Xiong, T. C.; Xu, H. M.; Wan, J. P.; Long, G. R.

2008-11-01

The residual stresses of the PMMA (polymethyl methacrylate) specimens after being drilled, reamed and polished respectively are investigated using the digital speckle correlation experimental method,. According to the displacement fields around the correlated calculated region, the polynomial curve fitting method is used to obtain the continuous displacement fields, and the strain fields can be obtained from the derivative of the displacement fields. Considering the constitutive equation of the material, the expression of the residual stress can be presented. During the data processing, according to the fitting effect of the data, the calculation region of the correlated speckles and the degree of the polynomial fitting curve is decided. These results show that the maximum stress is at the hole-wall of the drilling hole specimen and with the increasing of the diameter of the drilled hole, the residual stress resulting from the hole drilling increases, whereas the process of reaming and polishing hole can reduce the residual stress. The relative large discrete degree of the residual stress is due to the chip removal ability of the drill bit, the cutting feed of the drill and other various reasons.
Manufacturing inspection of electrical steels using Magnetic Barkhausen Noise: residual stress detection

Energy Technology Data Exchange (ETDEWEB)

Samimi, A.A., E-mail: 9aa8@queensu.ca [Queen' s Univ., Applied Magnetics Group, Kingston, Ontario (Canada); Krause, T.W. [Royal Military College of Canada, NDE Lab., Kingston, Ontario (Canada); Clapham, L. [Queen' s Univ., Applied Magnetics Group, Kingston, Ontario (Canada); Gallaugher, M.; Ding, Y.; Chromik, R. [McGill Univ., Dept. of Mining and Materials Engineering, Montreal, Quebec (Canada)

2016-09-15

Non-oriented Electrical Steel (NOES) is the magnetic core lamination material used for flux transfer in rotary machines. The presence of residual stress associated with material processing may be detrimental to magnetic domain structure refinement and as a result, magnetic performance of NOES. Therefore, manufacturing inspection of NOES that identifies the presence of residual stress could contribute to the production of more energy efficient cores. However, standard materials evaluation is limited to destructive and off-line techniques. The present work employed Magnetic Barkhausen Noise (MBN) for nondestructive identification of local residual stress associated with stages in material processing. Analysis of MBN from single strips of NOES demonstrated clear response to applied tensile stress, mechanical shearing, the presence of an insulating coating and punching. The results establish the potential of MBN as a nondestructive testing technology for quality control of electrical steels at various stages of manufacture. (author)
Optical residual stress measurement in TFT-LCD panels

Science.gov (United States)

Wang, Wei-Chung; Sung, Po-Chi

2017-06-01

The residual stress of the glass substrate might be one of causes to produce the non-uniform light distribution defect, i.e. Mura, in thin film transistor-liquid crystal display (TFT-LCD) panels. Glass is a birefringent material with very low birefringence. Furthermore, the thinner and thinner thickness request from the market makes the traditional photoelasticity almost impossible to measure the residual stresses produced in thin glass plates. Recently, a low-level stress measurement method called transmissivity extremities theory of photoelasticity (TEToP) was successfully developed to measure the residual stress in glass plate. Besides, to measure the stress of the glass plate in the TFT-LCD panel whose rear surface may has different kinds of coatings, an advanced reflection photoelasticity was also developed. In this paper, three commercially available glass plates with 0.33mm nominal thickness and three glass circular disks with different coatings were inspected to verify the feasibility of the TEToP and the advanced reflection photoelasticity, respectively.
Influence of residual stress on diffusion-induced bending in bilayered microcantilever sensors

International Nuclear Information System (INIS)

Xuan Fuzhen; Shao Shanshan; Wang Zhengdong; Tu Shantung

2010-01-01

The influence of residual stress on diffusion-induced bending in bilayered microcantilever sensors has been analyzed under the framework of thermodynamic theory and Fick's second law. A self-consistent diffusion equation involving the coupling effects of residual stress and diffusion-induced stress is developed. Effects of thickness ratio, modulus ratio, diffusivity ratio and residual stress gradient of film and substrate on the curvature of bilayered cantilever are then discussed with the help of finite difference method. Results reveal that the curvature of bilayered cantilever increases with decreasing the diffusivity ratio and modulus ratio of substrate to film at a given time. Case study of the polysilicon/palladium hydrogen sensor has been finally carried out using the above developed bending theory.
FEM simulation study on relationship of interfacial morphology and residual stress in TBCs

Energy Technology Data Exchange (ETDEWEB)

Liqiang Chen; Shengkai Gong; Huibin Xu [School of Materials Science and Engineering, Beihang Univ., Beijing, BJ (China)

2005-07-01

It is generally believed that the failure of TBCs is attributed to the spallation occurred in the ceramic coat. The spallation is closed linked with sinuate morphology factors, including its amplitude and period, at the TGO/bond coat interface. In this work, dependence of the residual stress distribution on the sinuate morphology in the TBCs has been studied by means of finite element method (FEM) simulation for isothermally annealed specimens. The simulation results indicated that the maximum value of residual stress existed inside the TGO layer. It was also found that the maximum residual stress occurred at different points, near the TGO/bond coat interface at the peak of the sinuate interface, while near the TGO/ceramic coat interface at the valley, respectively. And the maximum residual stress increased with increasing the ratio of the amplitude to period in the sine morphology, which has been proved by the thermal cycle experimental results. (orig.)
Residual Stress Analysis of Aircraft Part using Neutron Beam

Energy Technology Data Exchange (ETDEWEB)

Shin, Eun Joo; Seong, Baek Seok; Sim, Cheul Muu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

A precise measurement of the residual stress magnitude and distribution is an important factor to evaluate the lifetime or safety of the materials, because the residual stress affects the material properties, such as the strength, fatigue, etc. In the case of a fighter jet, the lifetime and safety of the parts of the landing gear are more important than that of a passenger airplane because of its frequent take offs and landings. In particular in the case of training a fighter jet, a precise evaluation of life time for the parts of the landing gear is strongly required for economic reason. In this study, the residual stress of a part of the landing gear of the training fighter jet which is used to fix the landing gear to the aircraft body was investigated. The part was used for 2000 hours of flight, which corresponds to 10 years. During this period, the fighter jet normally takes off and lands more than 2000 times. These frequent take off and landing can generate residual stress and cause a crack in the part. By measuring the neutron diffraction peaks, we evaluated the residual stress of the landing gear part
The maximum possible stress intensity factor for a crack in an unknown residual stress field

International Nuclear Information System (INIS)

Coules, H.E.; Smith, D.J.

2015-01-01

Residual and thermal stress fields in engineering components can act on cracks and structural flaws, promoting or inhibiting fracture. However, these stresses are limited in magnitude by the ability of materials to sustain them elastically. As a consequence, the stress intensity factor which can be applied to a given defect by a self-equilibrating stress field is also limited. We propose a simple weight function method for determining the maximum stress intensity factor which can occur for a given crack or defect in a one-dimensional self-equilibrating stress field, i.e. an upper bound for the residual stress contribution to K I . This can be used for analysing structures containing defects and subject to residual stress without any information about the actual stress field which exists in the structure being analysed. A number of examples are given, including long radial cracks and fully-circumferential cracks in thick-walled hollow cylinders containing self-equilibrating stresses. - Highlights: • An upper limit to the contribution of residual stress to stress intensity factor. • The maximum K I for self-equilibrating stresses in several geometries is calculated. • A weight function method can determine this maximum for 1-dimensional stress fields. • Simple MATLAB scripts for calculating maximum K I provided as supplementary material.
X-ray diffraction analysis of residual stresses in alumina-chromium composites and comparison with numerical simulations

Energy Technology Data Exchange (ETDEWEB)

Geandier, G.; Weisbecker, P.; Denis, S.; Mocellin, A. [L.S.G.2M., UMR, CNRS/INPL, Ecole des Mines de Nancy, Nancy (France); Hazotte, A. [L.S.G.2M., UMR, CNRS/INPL, Ecole des Mines de Nancy, Nancy (France); LETAM, UMR, CNRS/Metz Univ., ISGMP, Metz (France); Lebrun, J.L. [L.P.M.I., ENSAM Angers, Angers (France); Elkaim, E. [L.U.R.E., Centre Univ. Paris-Sud, Orsay (France)

2002-07-01

Residual stresses in alumina chromium composites have been determined using X ray synchrotron diffraction at LURE. Results show that non-negligible residual stresses exist in the composites. Mean residual stresses calculated by finite element show discrepancies with experimental values that are discussed in relation with experimental difficulties and calculation assumptions. (orig.)

Validation of Weld Residual Stress Modeling in the NRC International Round Robin Study

International Nuclear Information System (INIS)

Mullins, Jonathan; Gunnars, Jens

2013-01-01

Weld residual stresses (WRS) have a large influence on the behavior of cracks growing under normal operation loads and on the leakage flow from a through-wall crack. Accurate prediction on weld residual stresses is important to make proper decisions when cracks in weld joints are detected. During the latest years, there has been a strong development in both analytical procedures to numerically determine WRS and experimental measurements of WRS. The USNRC (United States Nuclear Regulatory Commission) has formed a program for validation of WRS predictions through comparison of numerically calculated residual stress fields in dissimilar welds measured by different methods. The present report describes the results of the project with special focus on the contribution from Inspecta Technology. Objectives: The principal objective of the project is to compare different WRS predictions for a dissimilar pipe weld with careful measurements on a mock-up weld. The results of the project will make it possible to make recommendations on computational procedures for WRS in dissimilar metal welds. Results: It is concluded that numerical analysis of weld residual stresses using the finite element method is very useful for the estimation of weld residual stresses in complex geometries and dissimilar metal welds. The validation study increases the understanding of uncertainties associated with different modeling approaches and helps to identify the most sensitive parameters
Measurement of residual stress in plasma-sprayed metallic, ceramic and composite coatings

Energy Technology Data Exchange (ETDEWEB)

Kesler, O.; Suresh, S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Matejicek, J.; Sampath, S. [State Univ. of New York, Stony Brook, NY (United States). Inst. for Mathematical Sciences; Gnaeupel-Herold, T.; Brand, P.C.; Prask, H.J. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

1998-12-15

Residual stresses in plasma-sprayed coatings were studied by three experimental techniques: curvature measurements, neutron diffraction and X-ray diffraction. Two distinct material classes were investigated: (1) single-material coatings (molybdenum) and (2) bi-material composites (nickel+alumina and NiCrAlY+yttria-stabilized zirconia), with and without graded layers. This paper deals with the effects of coating thickness and material properties on the evolution of residual stresses as a function of composition and thickness in both homogeneous and graded coatings. Mathematical analysis of the results allowed in some cases the separation of the quenching stress and thermal stress contributions to the final residual stress, as well as the determination of the through-thickness stress profile from measurements of different thickness specimens. In the ceramic-metal composites, it was found that the quenching stress plays a dominant role in the metallic phase, whereas the stress in the ceramic phase is mostly dominated by thermal mismatch. The respective thermal expansion coefficients and mechanical properties are the most important factors determining the stress sign and magnitude. The three residual stress measurement methods employed here were found to be complementary, in that each can provide unique information about the stress state. The most noteworthy outcomes are the determination of the through-thickness stress profile in graded coatings with high spatial resolution (curvature method) and determination of stress in each phase of a composite separately (neutron diffraction). (orig.) 25 refs.
Effect of residual stresses on fatigue strength of plasma nitrided 4140 steel

International Nuclear Information System (INIS)

Aghazadeh, J.; Amidi, M.R.

2004-01-01

Almost every method that has been presented to determine residual stress has some limitation and complexities. The aim of this work is to present a new, yet simple method so called strain indentation for measuring the residual stresses particularly in thin layers. In this method in addition to the precision measurements, components of residual stress at different directions may be determined. AISI 4140 steel specimens nitrided at 350 d ig C , 450 d ig C and 550 d ig C for 5 hours in the mixture of 75% nitrogen- 25% hydrogen gas. The, components of residual stress in the radials axial and hoop directions in the nitrided layer were determined considering the elastic strain recovery after removal of residual stress inducer(i.e. the nitrided layer). Fatigue strength of the nitrided specimens was obtained by plotting the S-N curves and fractographic studies carried out on the fracture surface of the specimens. The effect of residual stress on the stress pattern was simulated. The calculated residual stress components were in the range of 40-210 Mpa and the radial components of residual stress were more than the other two directions. Maximum fatigue strength improvement of up to 110% was observed in the plasma nitrided specimens at 550 d ig C and also 40% improvement in fatigue strength was detected by increasing the nitriding temperature from 350 d ig C to 550 d ig C . This was due to 100% increase in residual stress. Fatigue crack growth velocity in the hoop direction was more than that of radial direction. This seems to be due to higher radial residual stress component compared with the hoop stress component in the sub layer
Different finite element techniques to predict welding residual stresses in aluminum alloy plates

International Nuclear Information System (INIS)

Moein, Hadi; Sattari-Far, Iradj

2014-01-01

This study is a 3D thermomechanical finite element (FE) analysis of a single-pass and butt-welded work-hardened aluminum (Al) 5456 plates. It aims to validate the use of FE welding simulations to predict residual stress states in assessing the integrity of welded components. The predicted final residual stresses in the plate from the FE simulations are verified through comparison with experimental measurements. Three techniques are used to simulate the welding process. In the first two approaches, welding deposition is applied by using element birth and interaction techniques. In the third approach, the entire weld zone is simultaneously deposited. Results show a value at approximately the yield strength for longitudinal residual stresses of the welded center of the butt-welded Al alloy plates with a thickness of 2 mm. Considering the application of a comprehensive heat source, along with heat loss modeling and the temperature dependent properties of the material, the approach without deposition predicts a reasonable distribution of residual stresses. However, the element birth and interaction techniques, compared with the no-deposit technique, provide more accurate results in calculating residual stresses. Furthermore, the element interaction technique, compared with the element birth technique, exhibits higher efficiency and flexibility in modeling the deposition of welded metals as well as less modeling cost.
Experimental stress analysis for determination of residual stresses and integrity monitoring of components and systems

International Nuclear Information System (INIS)

1993-01-01

For an analysis of the safety-related significance of residual stresses, mechanical, magnetic as well as ultrasonic and diffraction methods can be applied as testing methods. The results of an interlaboratory test concerning the experimental determination of residual stresses in a railway track are included. Further, questions are analyzed concerning the in-service inspections of components and systems with regard to their operational safety and life. Measurement methods are explained by examples from power plant engineering, nuclear power plant engineering, construction and traffic engineering as well as aeronautics. (DG) [de
Novel approaches to determining residual stresses by ultramicroindentation techniques: Application to sandblasted austenitic stainless steel

International Nuclear Information System (INIS)

Frutos, E.; Multigner, M.; Gonzalez-Carrasco, J.L.

2010-01-01

This research addresses the determination of residual stresses in sandblasted austenitic steel by ultramicroindentation techniques using a sharp indenter, of which the sensitivity to residual stress effects is said to be inferior to that of spherical ones. The introduction of an angular correction in the model of Wang et al. which relates variations in the maximum load to the presence of residual stresses is proposed. Similarly, the contribution to the hardness of grain size refinement and work hardening, developed as a consequence of the severe plastic deformation during blasting, is determined in order to avoid overestimation of the residual stresses. Measurements were performed on polished cross sections along a length of several microns, thus obtaining a profile of the residual stresses. Results show good agreement with those obtained by synchrotron radiation on the same specimens, which validates the method and demonstrates that microindentation using sharp indenters may be sensitive to the residual stress effect.
Novel approaches to determining residual stresses by ultramicroindentation techniques: Application to sandblasted austenitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Frutos, E. [Centro de Bioingenieria, Biomateriales y Nanomedicina, CIBER-BBN, Instituto de Salud Carlos III (Spain)] [Centro Nacional de Investigaciones Metalurgicas, CENIM-CSIC, 28040 Madrid (Spain); Multigner, M. [Centro Nacional de Investigaciones Metalurgicas, CENIM-CSIC, 28040 Madrid (Spain)] [Centro de Bioingenieria, Biomateriales y Nanomedicina, CIBER-BBN, Instituto de Salud Carlos III (Spain); Gonzalez-Carrasco, J.L., E-mail: jlg@cenim.csic.es [Centro Nacional de Investigaciones Metalurgicas, CENIM-CSIC, 28040 Madrid (Spain)] [Centro de Bioingenieria, Biomateriales y Nanomedicina, CIBER-BBN, Instituto de Salud Carlos III (Spain)

2010-07-15

This research addresses the determination of residual stresses in sandblasted austenitic steel by ultramicroindentation techniques using a sharp indenter, of which the sensitivity to residual stress effects is said to be inferior to that of spherical ones. The introduction of an angular correction in the model of Wang et al. which relates variations in the maximum load to the presence of residual stresses is proposed. Similarly, the contribution to the hardness of grain size refinement and work hardening, developed as a consequence of the severe plastic deformation during blasting, is determined in order to avoid overestimation of the residual stresses. Measurements were performed on polished cross sections along a length of several microns, thus obtaining a profile of the residual stresses. Results show good agreement with those obtained by synchrotron radiation on the same specimens, which validates the method and demonstrates that microindentation using sharp indenters may be sensitive to the residual stress effect.
Neutron diffraction measurement of residual stress in NPP construction materials

International Nuclear Information System (INIS)

Hinca, R.; Bokuchava, G.

2000-01-01

The aim of the investigation is to study the level of residual stresses induced by the surfacing in the weld deposit zone and in the base metal, where considerable thermal gradients are present. Surfacing high-nickel filler on an austenitic base metal is one of techniques in repair of primary collector the primary circuit of nuclear power plant type VVER. The repair technology was developed at Welding Research Institute Bratislava. Measurements of residual stresses in the weld overlay and the base metal are necessary for approving the mechanical analysis and verifying of residual stresses determination on welded material by numerical weld g computer simulation. Investigations of residual stresses are important for developing optimal welding techniques. (authors)
On the residual stress modeling of shot-peened AISI 4340 steel: finite element and response surface methods

Science.gov (United States)

Asgari, Ali; Dehestani, Pouya; Poruraminaie, Iman

2018-02-01

Shot peening is a well-known process in applying the residual stress on the surface of industrial parts. The induced residual stress improves fatigue life. In this study, the effects of shot peening parameters such as shot diameter, shot speed, friction coefficient, and the number of impacts on the applied residual stress will be evaluated. To assess these parameters effect, firstly the shot peening process has been simulated by finite element method. Then, effects of the process parameters on the residual stress have been evaluated by response surface method as a statistical approach. Finally, a strong model is presented to predict the maximum residual stress induced by shot peening process in AISI 4340 steel. Also, the optimum parameters for the maximum residual stress are achieved. The results indicate that effect of shot diameter on the induced residual stress is increased by increasing the shot speed. Also, enhancing the friction coefficient magnitude always cannot lead to increase in the residual stress.
Neutron diffraction measurements of residual stress in a powder metallurgy component

International Nuclear Information System (INIS)

Schneider, L.C.R.; Hainsworth, S.V.; Cocks, A.C.F.; Fitzpatrick, M.E.

2005-01-01

Residual stresses in a typical industrial green component were determined using neutron diffraction. The measured residual stresses were found to correlate with cross-sectional variations. Residual stress at the edge of the compact in contact with the die wall during compaction reached up to +80 MPa (tension) and -100 MPa (compression)
Residual stresses in 2 1/4Cr1Mo welds

International Nuclear Information System (INIS)

Fidler, R.; Jerram, K.

1978-01-01

Two separate investigations, initiated in an attempt to explain the large amount of residual stress scatter previously observed in the weld metal of eighteen nominally identical thick-section 2 1/4Cr1Mo butt welds, are described in this paper. The first examined the detailed surface residual stress distributions in 2 1/4Cr1Mo manual arc circumferential butt welds in 80mm and 100mm thick 1/2Cr1/2Mo1/4V steam pipe. High residual stresses were found in the regions of overlap between adjacent weld beads, with low values in virgin weld metal. The second utilised single pass manual metal arc bead-in-groove welds to investigate the effects of preheat and weld metal composition on weld metal residual stresses. In four weld metals, mild steel, 1/2Cr1/2Mo1/4V, 1Cr1/2Mo, and 2 1/4Cr1Mo, the residual stresses were very similar, becoming less tensile (or more compressive) with increase of preheat, while the residual stresses in the fifth weld metal (12Cr) were significantly different, being compressive and less affected by preheat. In both investigations the effects have been described in terms of the basic metallurgical phenomena occurring in the weld metal. (author)
Analysis of residual stresses in a long hollow cylinder

International Nuclear Information System (INIS)

Tokovyy, Yuriy V.; Ma, Chien-Ching

2011-01-01

This paper presents an analytical method for solving the axisymmetric stress problem for a long hollow cylinder subjected to locally-distributed residual (incompatible) strains. This method is based on direct integration of the equilibrium and compatibility equations, which thereby have been reduced to the set of two governing equations for two key functions with corresponding boundary and integral conditions. The governing equations were solved by making use of the Fourier integral transformation. Application of the method is illustrated with an analysis of the welding residual stresses in a butt-welded thick-walled pipe. - Highlights: → A solution to the axisymmetric stress problem for a hollow cylinder is constructed. → The cylinder is subjected to a field of locally-distributed residual strains. → The method is based on direct integration of the equilibrium equations. → An application of our solution to analysis of welding residual stresses is considered.
Effects of distance from center of a weld to fixed end on residual stress and stress intensity factor of a piping weld. Evaluation of SCC growth under residual stress field. Report 1

International Nuclear Information System (INIS)

Miyazaki, Katsumasa; Numata, Masanori; Saito, Koichi; Mochizuki, Masahito

2006-01-01

The fixed conditions of butt welds between straight pipe and valve or pump in the actual piping system are different from those of straight pipes. However, the effect of fixed condition on the residual stress and the stress intensity factor for evaluation of structural integrity of cracked piping was not clear. In this study, the finite element analyses were conducted by considering the differences in the distance from the center of weld to the fixed end L to clarify the effect of fixed condition on the residual stress and the stress intensity factor. For the 600 A piping, the axial residual stress distribution was not affected by the distance L. Furthermore, the stress intensity factor of circumferential crack under the residual stress field with fixed condition could be estimated by using the existing simplified solution for piping. (author)
Effects of fretting fatigue on the residual stress of shot peened Ti-6Al-4V samples

International Nuclear Information System (INIS)

Martinez, S.A.; Sathish, S.; Blodgett, M.P.; Mall, S.; Namjoshi, S.

2005-01-01

X-ray diffraction residual stress measurement has been utilized as nondestructive tool for the characterization of fretting fatigue damage in shot peened samples of Ti-6Al-4V. Prior to fretting fatigue damage, compressive residual stresses were found to be uniform over the entire face of the sample and independent of the measurement direction. After fretting fatigue, inside and in the vicinity of the fretting damage zone large relaxation of compressive residual stress was observed. An anisotropic residual stress distribution has been observed in the fretting fatigue damaged region. Residual stress measurements in interrupted fretting fatigue experiments showed that the relaxation of residual stress increases as the number of fretting fatigue cycles increase. The results are discussed in the light of their importance in establishing X-ray diffraction residual stress measurement technique as a nondestructive tool to characterize fretting fatigue damage
Effects of residual stress on irradiation hardening in stainless steels

Energy Technology Data Exchange (ETDEWEB)

Okubo, N.; Kondo, K.; Kaji, Y. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Miwa, Y. [Nuclear Energy and Science Directorate, Japan Atomic Energy Agency, Tokai-mura, Ibaraki-ken (Japan)

2007-07-01

Full text of publication follows: Structural materials in fusion reactor with water cooling system will undergo corrosion in aqueous environment and heavier irradiation than that in LWR. Irradiation assisted stress corrosion (IASCC) may be induced in stainless steels exposed in these environment for a long term of reactor operation. The IASCC is considered to be caused in a welding zone. It is difficult to predict and estimate the IASCC, because several irradiation effects (irradiation hardening, swelling, irradiation induced stress relaxation, etc) work intricately. Firstly, effects of residual stress on irradiation hardening were investigated in stainless steels. Specimens used in this study were SUS316 and SUS316L. By bending deformation, the specimens with several % plastic strain, which corresponds to weld residual stress, were prepared. Ion irradiations of 12 MeV Ni{sup 3+} were performed at 330, 400 and 550 deg. C to 45 dpa in TIARA facility at JAEA. No bent specimen was simultaneously irradiated with the bent specimen. The residual stress was estimated by X-ray residual stress measurements before and after the irradiation. The micro-hardness was measured by using nano-indenter. The irradiation hardening and the stress relaxation were changed by irradiation under bending deformation. The residual stress did not relax even for the case of the higher temperature aging at 500 deg. C for the same time of irradiation. The residual stress after ion irradiation, however, relaxed at these experimental temperatures in SUS316L. The hardness was obviously suppressed in bent SUS316L irradiated at 300 deg. C to 6 or 12 dpa. It was evident that irradiation induced stress relaxation occasionally suppressed the irradiation hardening in SUS316L. (authors)
Reduction of tensile residual stresses during the drawing process of tungsten wires

International Nuclear Information System (INIS)

Rodriguez Ripoll, Manel; Weygand, Sabine M.; Riedel, Hermann

2010-01-01

Tungsten wires are commonly used in the lighting industry as filaments for lamps. During the drawing process, the inhomogeneous deformation imparted by the drawing die causes tensile residual stresses at the wire surface in circumferential direction. These stresses have a detrimental effect for the wire because they are responsible for driving longitudinal cracks, known as splits. This work proposes two methods for reducing the residual stresses during wire drawing, namely applying an advanced die geometry and performing an inexpensive post-drawing treatment based on targeted bending operations. These two methods are analyzed with finite element simulations using material parameters obtained by mechanical tests on tungsten wires at different temperatures as input data. The computed results predict a substantial reduction of the circumferential residual stresses, thus reducing the risk of splitting.
Measurement of residual stress in plasma-sprayed composite coatings with graded and uniform compositions

Energy Technology Data Exchange (ETDEWEB)

Kesler, O.; Suresh, S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Matejicek, J.; Sampath, S.

1999-10-01

Residual stresses in plasma sprayed composite coatings were studied experimentally by both curvature and neutron diffraction measurements. Graded and uniform composite coatings, consisting of nickel + alumina and NiCrAlY + yttria-stabilized zirconia, were investigated. This paper briefly summarizes our recent work dealing with the effects of coating thickness, composition, and material properties on the evolution of residual stresses in coatings. Analysis of the results allowed in some cases the separation of the quenching stress and thermal stress contributions to the final residual stress, as well as the determination of the through-thickness stress profile from measurements of different thickness specimens. In the ceramic-metal composites, it was found that the thermal mismatch stress plays a dominant role in the ceramic phase, whereas the stress in the metallic phase is mostly dominated by quenching stress. The residual stress measurement methods employed here were found to be complementary, in that each can provide unique information about the stress state. Through-thickness stress profiles in graded coatings were determined with high spatial resolution by the curvature method, and determination of the stress in each separate phase of a composite was made by neutron diffraction. (orig.) 14 refs.
Modeling of residual stress mitigation in austenitic stainless steel pipe girth weldment

International Nuclear Information System (INIS)

Li, M.; Atteridge, D.G.; Anderson, W.E.; West, S.L.

1994-01-01

This study provides numerical procedures to model 40-cm-diameter, schedule 40, Type 304L stainless steel pipe girth welding and a newly proposed post-weld treatment. The treatment can be used to accomplish the goal of imparting compressive residual stresses at the inner surface of a pipe girth weldment to prevent/retard the intergranular stress corrosion cracking (IGSCC) of the piping system in nuclear reactors. This new post-weld treatment for mitigating residual stresses is cooling stress improvement (CSI). The concept of CSI is to establish and maintain a certain temperature gradient across the pipe wall thickness to change the final stress state. Thus, this process involves sub-zero low temperature cooling of the inner pipe surface of a completed girth weldment, while simultaneously keeping the outer pipe surface at a slightly elevated temperature with the help of a certain heating method. Analyses to obtain quantitative results on pipe girth welding and CSI by using a thermo-elastic-plastic finite element model are described in this paper. Results demonstrate the potential effectiveness of CSI for introducing compressive residual stresses to prevent/retard IGSCC. Because of the symmetric nature of CSI, it shows great potential for industrial application
Diffraction Plane Dependence of Micro Residual Stresses in Uniaxially Extended Carbon Steels

Directory of Open Access Journals (Sweden)

T. Hanabusa

2010-12-01

Full Text Available In the stress measurement using X-ray or neutron diffraction, an elastic anisotropy as well as a plastic anisotropy of crystal must be carefully considered. In the X-ray and neutron diffraction stress measurement for polycrystalline materials, a particular {hkl} plane is used in measuring lattice strains. The dependence of an X-ray elastic constant on a diffraction plane is a typical example caused by an elastic anisotropy of the crystal. The yield strength and the work hardening rate of a single crystal depend on a crystallographic direction of the crystal. The difference in the yield strength and the work hardening rate relating to the crystallographic direction develops different residual stresses measured on each {hkl} diffraction after plastic deformation of a polycrystalline material. The present paper describes the result of the neutron stress measurement on uniaxially extended low and middle carbon steels. A tri-axial residual stress state developed in the extended specimens was measured on different kind of {hkl} diffraction plane. The measurement on the {110}, {200} and {211} diffraction showed that residual stresses increased with increasing the plastic elongation and the residual stresses on {110} were compressive, {200} were tensile and those on {211} were the middle of the former two planes.
A coupled creep plasticity model for residual stress relaxation of a shot-peened nickel-based superalloy

Science.gov (United States)

Buchanan, Dennis J.; John, Reji; Brockman, Robert A.; Rosenberger, Andrew H.

2010-01-01

Shot peening is a commonly used surface treatment process that imparts compressive residual stresses into the surface of metal components. Compressive residual stresses retard initiation and growth of fatigue cracks. During component loading history, shot-peened residual stresses may change due to thermal exposure, creep, and cyclic loading. In these instances, taking full credit for compressive residual stresses would result in a nonconservative life prediction. This article describes a methodical approach for characterizing and modeling residual stress relaxation under elevated temperature loading, near and above the monotonic yield strength of INI 00. The model incorporates the dominant creep deformation mechanism, coupling between the creep and plasticity models, and effects of prior plastic strain to simulate surface treatment deformation.

Influence of repair length on residual stress in the repair weld of a clad plate

International Nuclear Information System (INIS)

Jiang Wenchun; Xu, X.P.; Gong, J.M.; Tu, S.T.

2012-01-01

Highlights: ► Residual stress in the repair weld of a stainless steel clad plate is investigated. ► The effect of repair length on residual stress has been studied. ► Large tensile residual stress is generated in the repair weld and heat affected zone. ► With the increase of repair length, transverse stress is decreased. ► Repair length has little effect on longitudinal stress. - Abstract: A 3-D sequential coupling finite element simulation is performed to investigate the temperature field and residual stress in the repair weld of a stainless steel clad plate. The effect of repair length on residual stress has been studied, aiming to provide a reference for repairing the cracked clad plate. The results show that large tensile residual stresses are generated in the repair weld and heat affected zone (HAZ), and then decrease gradually away from the weld and HAZ. The residual stresses through thickness in the clad layer are relative uniform, while they are non-uniform in the base metal. A discontinuous stress distribution is generated across the interface between weld metal and base metal. The repair length has a great effect on transverse stress. With the increase of repair length, the transverse stress is decreased. When the repair length is increased to 14 cm, the peak of transverse stress has been decreased below yield strength, and the transverse stress in the weld and HAZ has also been greatly decreased. But the repair length has little effect on longitudinal stress.
Thermal residual stress evaluation based on phase-shift lateral shearing interferometry

Science.gov (United States)

Dai, Xiangjun; Yun, Hai; Shao, Xinxing; Wang, Yanxia; Zhang, Donghuan; Yang, Fujun; He, Xiaoyuan

2018-06-01

An interesting phase-shift lateral shearing interferometry system was proposed to evaluate the thermal residual stress distribution in transparent specimen. The phase-shift interferograms was generated by moving a parallel plane plate. Based on analyzing the fringes deflected by deformation and refractive index change, the stress distribution can be obtained. To verify the validity of the proposed method, a typical experiment was elaborately designed to determine thermal residual stresses of a transparent PMMA plate subjected to the flame of a lighter. The sum of in-plane stress distribution was demonstrated. The experimental data were compared with values measured by digital gradient sensing method. Comparison of the results reveals the effectiveness and feasibility of the proposed method.
Residual stress in deuterium implanted nominal copper coatings

International Nuclear Information System (INIS)

Inal, M. Y.; Alam, M.; Peascoe, R. A.; Watkins, T. R.

2000-01-01

The effects of deuterium (D) implantation on the residual stresses in Cu and CuAl 2 phases present in nominal Cu coatings (containing Al) deposited on Al-alloy (Al-6061) substrates were measured using an x-ray diffraction technique. The coatings were deposited by radio frequency magnetron sputtering of a pure Cu target under identical conditions and Al was incorporated in the coatings during growth by diffusion from the substrate. Deuterium was implanted in the coatings at energies of 40 or 40+120 keV with fluences of 1x10 21 , 2x10 21 , or 3x10 21 D + /m 2 . Pole figures of the Cu phase in the coatings prior to and after implantation indicated no effect of implantation on the fibrous texture. Triaxial stress analysis indicated the surface normal stress component to be negligible in Cu and slightly tensile in CuAl 2 under all conditions. Furthermore, under all conditions, the in-plane residual stresses in both phases were found to be compressive and nearly isotropic. The magnitude of the isotropic compressive stress was always higher in CuAl 2 as compared to Cu. The compressive residual stresses in the Cu phase changed only mildly with increasing coating weight, ion energy, and fluence. However, in the CuAl 2 phase the compressive residual stresses changed markedly with increasing ion energy (initial decrease followed by leveling off) and increasing ion fluence (initial decrease followed by an increase), but remained unaffected by increasing coating weight. (c) 2000 American Institute of Physics
finite element model for predicting residual stresses in shielded

African Journals Online (AJOL)

eobe

This paper investigates the prediction of residual stresses developed ... steel plates through Finite Element Model simulation and experiments. ... The experimental values as measured by the X-Ray diffractometer were of ... Based on this, it can be concluded that Finite Element .... Comparison of Residual Stresses from X.
Welding induced residual stress evaluation using laser-generated Rayleigh waves

Science.gov (United States)

Ye, Chong; Zhou, Yuanlai; Reddy, Vishnu V. B.; Mebane, Aaron; Ume, I. Charles

2018-04-01

Welding induced residual stress could affect the dimensional stability, fatigue life, and chemical resistance of the weld joints. Ultrasonic method serves as an important non-destructive tool for the residual stress evaluation due to its easy implementation, low cost and wide application to different materials. Residual stress would result in the ultrasonic wave velocity variation, which is the so called acoustoelastic effect. In this paper, Laser/EMAT ultrasonic technique was proposed to experimentally study the relative velocity variation ΔV/V of Rayleigh wave, which has the potential to evaluate surface/subsurface longitudinal residual stress developed during the Gas Metal Arc Welding process. Broad band ultrasonic waves were excited by pulsed Q-Switched Nd: YAG laser. An electromagnetic acoustic transducer (EMAT) attached to the welded plates was used to capture the Rayleigh wave signals propagating along the weld seam direction. Different time of flight measurements were conducted by varying the distance between the weld seam and Rayleigh wave propagating path in the range of 0 to 45 mm. The maximum relative velocity difference was found on the weld seam. With the increasing distance away from the weld seam, the relative velocity difference sharply decreased to negative value. With further increase in distance, the relative velocity difference slowly increased and approached zero. The distribution of relative velocity variations indicates that tensile stress appears in the melted zone as it becomes compressive near the heat-affected zone.
The measurement of residual stresses in claddings

International Nuclear Information System (INIS)

Hofer, G.; Bender, N.

1978-01-01

The ring core method, a variation of the hole drilling method for the measurement of biaxial residual stresses, has been extended to measure stresses from depths of about 5 to 25mm. It is now possible to measure the stress profiles of clad material. Examples of measured stress profiles are shown and compared with those obtained with a sectioning technique. (author)
Investigation of residual stresses in thick-walled vessels with combination of autofrettage and wire-winding

International Nuclear Information System (INIS)

Sedighi, M.; Jabbari, A.H.

2013-01-01

Wire-winding and autofrettage processes can be used to introduce beneficial residual stress in the cylinder of thick-walled pressure vessels. In both techniques, internal residual compressive stress will increase internal pressure capacity, improve fatigue life and reduce fatigue crack initiation. The purpose of this paper is to analyze the effects of wire-winding on an autofrettaged thick-walled vessel. Direct method which is a modified Variable Material Properties (VMP) method has been used in order to calculate residual stresses in an autofrettaged vessel. Since wire-winding is done after autofrettage process, the tangent and/or Young's modulus could be changed. For this reason, a new wire-winding method based on Direct Method is introduced. The obtained results for wire-wound autofrettaged vessels are validated by finite element method. The results show that by using this approach, the residual hoop stresses in a wire-wound autofrettaged vessel have a more desirable distribution in the cylinder. -- Highlights: • Combination of autofrettage and wire-winding in pressure vessels has been presented. • A new method based on Direct method is presented for wire-winding process. • Residual hoop stresses are compared in vessels cylinders for different cases. • The residual hoop stress has a more desirable stress distribution. • The benefits of the combined vessel are highlighted in comparison with single cases
Simulation of Residual Stresses at Holes in Tempered Glass

DEFF Research Database (Denmark)

Nielsen, Jens Henrik; Olesen, John Forbes; Poulsen, Peter Noe

2010-01-01

This work presents a full 3D numerical study of the residual stresses in tempered (toughened) glass near holes using Narayanaswamy’s model for the tempering process. It is the objective of the paper to elucidate the influence on the minimal residual compressive stresses at holes from variations in...
Residual stresses in U-bending deformations and expansion joints of heat exchanger tubes

International Nuclear Information System (INIS)

Kim, Woo Gon; Kim, Sun Jae; Jang, Jin Sung; Kuk, Ii Hiun; Bae, Kang Gug; Kim, Sung Chung

2000-01-01

Residual stress induced in U-bending and tube-to-tubesheet joint processes of PWR's rew-1 heat exchanger tube was measured by X-ray method and Hole-Drilling Method(HDM). Compressive residual stresses(-) at the extrados surface were induced in U-bending, and its maximum value reached -319MPa in axial direction at the position of ψ=0 deg. Tensile residual stresses (+) of 0σ zz =45 MPa and σ θθ =25MPa were introduced in the intrados surface at the position of ψ=0 deg. Maximum tensile residual stress of 170 MPa was measured at the flank side at the position of ψ=90 deg, i.e., at apex region. It was observed that higher stress gradient was generated at the irregular transition regions (ITR). The trend of residual stress induced by U-bending process of the tubes was found to be related with the change of ovality. The residual stress induced by the explosive joint method was found to be lower than that by the mechanical roll method. The gradient of residual stress along the expanded tube was highest at the transition region (TR), and the residual stress in circumferential direction was found to be higher than the residual stress in axial direction
A Study on Residual Stress Measurements by Using Laser Speckle Interferometry

International Nuclear Information System (INIS)

Rho, Kyung Wan; Kang, Young June; Hong, Seong Jin; Kang, Hyung Soo

1999-01-01

Residual stress is one of the causes which make defects in engineering components and materials. And interest in the measurement of residual stress exists in many industries. There are commonly used methods by which residual stresses are currently measured. But these methods have a little demerits: time consumption and other problems. Therefore we devised a new experimental technique to measure residual stress in materials with a combination of laser speckle pattern interferometry, finite element method and spot heating. The speckle pattern interferometer measures in-plane deformations while the heating provides for very localized stress relief. FEM is used for determining heat temperature and other parameters. The residual stresses are determined by the amount of strain that is measured subsequent to the heating and cool-down of the region being interrogated. A simple model is presented to provide a description of the method. In this paper, the ambiguity problem for the fringe patterns has solved by a phase shifting method
Feasibility of Residual Stress Nondestructive Estimation Using the Nonlinear Property of Critical Refraction Longitudinal Wave

Directory of Open Access Journals (Sweden)

Yu-Hua Zhang

2017-01-01

Full Text Available Residual stress has significant influence on the performance of mechanical components, and the nondestructive estimation of residual stress is always a difficult problem. This study applies the relative nonlinear coefficient of critical refraction longitudinal (LCR wave to nondestructively characterize the stress state of materials; the feasibility of residual stress estimation using the nonlinear property of LCR wave is verified. The nonlinear ultrasonic measurements based on LCR wave are conducted on components with known stress state to calculate the relative nonlinear coefficient. Experimental results indicate that the relative nonlinear coefficient monotonically increases with prestress and the increment of relative nonlinear coefficient is about 80%, while the wave velocity only decreases about 0.2%. The sensitivity of the relative nonlinear coefficient for stress is much higher than wave velocity. Furthermore, the dependence between the relative nonlinear coefficient and deformation state of components is found. The stress detection resolution based on the nonlinear property of LCR wave is 10 MPa, which has higher resolution than wave velocity. These results demonstrate that the nonlinear property of LCR wave is more suitable for stress characterization than wave velocity, and this quantitative information could be used for residual stress estimation.
Residual stress in ceramics and ceramic composites

International Nuclear Information System (INIS)

Oden, M.

1992-01-01

Residual stresses in Si 3 N 4 and SiC have been measured with X-ray diffraction after grinding and thermal shock. The produced surface stresses are compressive after both treatments. The stresses show a strong dependence on the quenching temperature up to a certain temperature when cracks relax the stresses. The influence of the amount of reinforcing phase on the residual stress state in a Al 2 O 3 /SiC whisker composite was investigated and correlated to a modified Eshelby model. The agreement is excellent. The composite was quenched in liquid He (4K) and the stress state measured after show no relaxation of stresses, indicating elastic behaviour. An in situ strain measurement as a function of temperature conducted on a Al 2 O 3 /SiC whisker composite and a SiC/TiB 2 particle composite show very good agreement with the Eshelby model for the Al 2 O 3 /SiC system but not agreement for the SiC/TiB 2 system. The reason is believed to be stress relaxation during sample preparation. (au) (53 refs., 24 figs., 14 tabs.)
Residual stress evolution regularity in thermal barrier coatings under thermal shock loading

Directory of Open Access Journals (Sweden)

Ximin Chen

2014-01-01

Full Text Available Residual stress evolution regularity in thermal barrier ceramic coatings (TBCs under different cycles of thermal shock loading of 1100°C was investigated by the microscopic digital image correlation (DIC and micro-Raman spectroscopy, respectively. The obtained results showed that, as the cycle number of the thermal shock loading increases, the evolution of the residual stress undergoes three distinct stages: a sharp increase, a gradual change, and a reduction. The extension stress near the TBC surface is fast transformed to compressive one through just one thermal cycle. After different thermal shock cycles with peak temperature of 1100°C, phase transformation in TBC does not happen, whereas the generation, development, evolution of the thermally grown oxide (TGO layer and micro-cracks are the main reasons causing the evolution regularity of the residual stress.
The effect of tensioning and sectioning on residual stresses in aluminium AA7749 friction stir welds

International Nuclear Information System (INIS)

Altenkirch, J.; Steuwer, A.; Peel, M.; Richards, D.G.; Withers, P.J.

2008-01-01

Using synchrotron X-ray diffraction the residual stress distribution has been measured in a series of AA7449-W51 aluminium friction stir welds that had been tensioned to different loads during welding. By modifying the stress accumulation path, the application of a tensioning stress has reduced the tensile magnitude of the final residual weld stresses. In the present case the residual stresses were minimised when the applied load is ∼35% of the room temperature yield stress of the parent material. Subsequent sectioning of the weld into shorter test lengths, as might be necessary for weld testing, resulted in a progressive and significant relaxation of the residual stress field. The effect of tensioning on the weld component distortion also has been investigated
Forging And Milling Contribution On Residual Stresses For A Textured Biphasic Titanium Alloy

International Nuclear Information System (INIS)

Deleuze, C.; Fabre, A.; Barrallier, L.; Molinas, O.

2011-01-01

Ti-10V-2Fe-3Al is a biphasic titanium alloy (α+β) used in aeronautical applications for its mechanical properties, such as its yield strength of 1200 MPa and it weighs 40% less than steel. This alloy is particularly useful for vital parts with complex geometry, because of its high forging capability. In order to predict the capability for fatigue lifetime, the designers need to know the residual stresses. X-Ray diffraction is the main experimental technique used to determine residual stresses on the surface. In this case, stress levels are primarily influenced by the complex forging and milling process. On this alloy in particular, it may be difficult to characterize stress due to modification of the microstructure close to the surface. Results obtained by x-ray analysis depend on the correct definition of the shape of the diffraction peaks. The more precisely defined the position of the peak, the more accurately the stresses are evaluated. This paper presents a method to detect if residual stresses can be characterized by x-ray diffraction. The characterization of hardness seems to be a relevant technique to quickly analyze the capability of x-ray diffraction to determine residual stresses.
Joining of molybdenum disilicide to stainless steel using amorphous metal brazes - residual stress analysis

Energy Technology Data Exchange (ETDEWEB)

Vaidya, R.U.; Gallegos, D.E.; Kautz, D.D. [Los Alamos National Lab. (United States)

2007-07-01

Molybdenum disilicide (MoSi{sub 2})/stainless steel 316 L joints were produced by high temperature brazing using a cobalt-based metallic-glass (METGLAS trademark 2714A). Successful joining was completed in two different ways; either by feeding excess braze into the braze gap upon heating or by constraining the MoSi{sub 2}/stainless steel assembly with an alumina (Al{sub 2}O{sub 3}) fixture during the heating cycle. These steps were necessary to ensure the production of a high quality void free joint. Residual stress measurements were completed on these joints. Indentation results show higher tensile residual stresses in the stainless steel for the joint with the external constraint, in comparison to the unconstrained state. In contrast, the compressive residual stresses in the MoSi{sub 2} (as measured by X-ray diffraction) were lower in the constrained state relative to the unconstrained state. These results and a lack of residual stress balance indicate that the stress state in the braze is significantly different under the two joining conditions and the volume of the braze plays an important role in the development of the residual stresses. Push-out tests carried out on these joints gave higher joint strengths in the unconstrained as compared to the constrained condition. The results of this study have important implications on the selection of the appropriate joining process (use of constraint versus extra braze). (orig.)
Effects of thermal residual stresses and fiber packing on deformation of metal-matrix composites

International Nuclear Information System (INIS)

Nakamura, T.; Suresh, S.

1993-01-01

The combined effects of thermal residual stresses and fiber spatial distribution on the deformation of a 6061 aluminum alloy containing a fixed concentration unidirectional boron fibers have been analyzed using detailed finite element models. The geometrical structure includes perfectly periodic, uniformly space fiber arrangements in square and hexagonal cells, as well as different cells in which either 30 or 60 fibers are randomly placed in the ductile matrix. The model involves an elastic-plastic matrix, elastic fibers, and mechanically bonded interfaces. The results indicate that both fiber packing and thermal residual stresses can have a significant effect on the stress-strain characteristics of the composite. The thermal residual stresses cause pronounced matrix yielding which also influences the apparent overall stiffness of the composite during the initial stages of subsequent far-field loading along the axial and transverse direction. Furthermore, the thermal residual stresses apparently elevate the flow stress of the composite during transverse tension. Such effects can be traced back to the level of constraint imposed on the matrix by local fiber spacing. The implications of the present results to the processing of the composites are also briefly addressed
Effects of Cutting Edge Microgeometry on Residual Stress in Orthogonal Cutting of Inconel 718 by FEM.

Science.gov (United States)

Shen, Qi; Liu, Zhanqiang; Hua, Yang; Zhao, Jinfu; Lv, Woyun; Mohsan, Aziz Ul Hassan

2018-06-14

Service performance of components such as fatigue life are dramatically influenced by the machined surface and subsurface residual stresses. This paper aims at achieving a better understanding of the influence of cutting edge microgeometry on machined surface residual stresses during orthogonal dry cutting of Inconel 718. Numerical and experimental investigations have been conducted in this research. The cutting edge microgeometry factors of average cutting edge radius S¯, form-factor K , and chamfer were investigated. An increasing trend for the magnitudes of both tensile and compressive residual stresses was observed by using larger S¯ or introducing a chamfer on the cutting edges. The ploughing depth has been predicted based on the stagnation zone. The increase of ploughing depth means that more material was ironed on the workpiece subsurface, which resulted in an increase in the compressive residual stress. The thermal loads were leading factors that affected the surface tensile residual stress. For the unsymmetrical honed cutting edge with K = 2, the friction between tool and workpiece and tensile residual stress tended to be high, while for the unsymmetrical honed cutting edge with K = 0.5, the high ploughing depth led to a higher compressive residual stress. This paper provides guidance for regulating machine-induced residual stress by edge preparation.
Residual stresses and mechanical properties of metal matrix composites

International Nuclear Information System (INIS)

Persson, Christer.

1993-01-01

The large difference in coefficient of thermal expansion of the matrix and particles in a metal matrix composite will introduce residual stresses during cooling from process temperature. These stresses are locally very high, and are known to influence the mechanical behaviour of the material. Changes in the stress state will occur during heat treatments and when the material is loaded due to different elastic, plastic, and creep properties of the constituents. The change of residual stresses in an Al-SiC particulate composite after different degree of plastic straining has been studied. The effect of plastic straining was modelled by an Eshelby model. The model and the measurements both show that the stress in the loading direction decreases for a tensile plastic strain and increases for a compressive plastic strain. By x-ray diffraction the stress response in the matrix and particles can be measured independently. This has been used to determine the stress state under and after heat treatments and under mechanical loading in two Al 15% SiC metal matrix composites. By analysing the line width from x-ray experiment the changes in the microstrains in the material were studied. A finite element model was used to model the generation of thermal residual stresses, stress relaxation during heat treatments, and load sharing during the first load cycle. Calculated stresses and microstrains were found to be in good agreement with the measured values. The elastic behaviour of the composite can be understood largely in terms of elastic load transfer between matrix and particles. However, at higher loads when the matrix becomes plastic residual stresses also become important. 21 refs
Residual stresses under quasi-static and cyclic loading in shot peened Inconel 718

Energy Technology Data Exchange (ETDEWEB)

Hoffmeister, Juergen; Schulze, Volker [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Applied Materials; Hessert, Roland; Koenig, Gerhard [MTU Aero Engines, Munich (Germany)

2012-01-15

The residual stress state induced by shot peening should be taken into account in the dimensioning of turbine components. Understanding the changes in the residual stress state caused by the application of quasi-static and cyclic loads is a prerequisite. In order to describe the residual stress state after quasi-static loading, several different shot peened Inconel 718 specimens were loaded isothermally up to specific tensile loadings. To analyze the residual stress state after cyclic loading, isothermal low cycle fatigue tests were performed. These tests were stopped after a defined number of cycles. Finally, after the specimens had been subjected to different loads, the surface residual stresses and - for special loadings - the residual stress depth distributions were determined experimentally by using X-ray diffraction. The surface - core model was adapted so that the complete residual stress depth distribution after quasi-static and cyclic loading can now be described. (orig.)

Uncertainty Quantification and Comparison of Weld Residual Stress Measurements and Predictions.

Energy Technology Data Exchange (ETDEWEB)

Lewis, John R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brooks, Dusty Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-10-01

In pressurized water reactors, the prevention, detection, and repair of cracks within dissimilar metal welds is essential to ensure proper plant functionality and safety. Weld residual stresses, which are difficult to model and cannot be directly measured, contribute to the formation and growth of cracks due to primary water stress corrosion cracking. Additionally, the uncertainty in weld residual stress measurements and modeling predictions is not well understood, further complicating the prediction of crack evolution. The purpose of this document is to develop methodology to quantify the uncertainty associated with weld residual stress that can be applied to modeling predictions and experimental measurements. Ultimately, the results can be used to assess the current state of uncertainty and to build confidence in both modeling and experimental procedures. The methodology consists of statistically modeling the variation in the weld residual stress profiles using functional data analysis techniques. Uncertainty is quantified using statistical bounds (e.g. confidence and tolerance bounds) constructed with a semi-parametric bootstrap procedure. Such bounds describe the range in which quantities of interest, such as means, are expected to lie as evidenced by the data. The methodology is extended to provide direct comparisons between experimental measurements and modeling predictions by constructing statistical confidence bounds for the average difference between the two quantities. The statistical bounds on the average difference can be used to assess the level of agreement between measurements and predictions. The methodology is applied to experimental measurements of residual stress obtained using two strain relief measurement methods and predictions from seven finite element models developed by different organizations during a round robin study.
Study of residual stresses in CT test specimens welded by electron beam

Science.gov (United States)

Papushkin, I. V.; Kaisheva, D.; Bokuchava, G. D.; Angelov, V.; Petrov, P.

2018-03-01

The paper reports result of residual stress distribution studies in CT specimens reconstituted by electron beam welding (EBW). The main aim of the study is evaluation of the applicability of the welding technique for CT specimens’ reconstitution. Thus, the temperature distribution during electron beam welding of a CT specimen was calculated using Green’s functions and the residual stress distribution was determined experimentally using neutron diffraction. Time-of-flight neutron diffraction experiments were performed on a Fourier stress diffractometer at the IBR-2 fast pulsed reactor in FLNP JINR (Dubna, Russia). The neutron diffraction data estimates yielded a maximal stress level of ±180 MPa in the welded joint.
Effect of constraint condition and internal medium on residual stress under overlay welding for dissimilar metal welding

International Nuclear Information System (INIS)

Song, Tae Kwang; Kim, Yun Jae; Lee, Kyoung Soo; Park, Chi Yong; Kim, Jong Sung; Kim, Jin Weon

2007-01-01

In nuclear power plants, residual stress of dissimilar metal weld propagates cracks in the weld metal which is susceptible to stress corrosion cracking. Overlay welding is a process widely used to mitigate residual stress replacing inside tensile stress by compression stress. However, according to the result of this study the effect of overlay welding on residual stress depends on both internal medium and constraint condition. The purpose of this study is to maximize the positive effect of overlay welding by finite element analyses
Residual stress evaluation and curvature behavior of aluminum 7050 peen forming processed

International Nuclear Information System (INIS)

Oliveira, Rene Ramos de

2011-01-01

Shot peening is a superficial cold work process used to increase the fatigue life evaluated by residual stress measurements. The peen forming process is a variant of the shot peening process, where a curvature in the plate is obtained by the compression of the grains near to the surface. In this paper, the influence of the parameters such as: pressure of shot, ball shot size and thickness of aluminum 7050 samples with respect to residual stress profile and resulting arc height was studied. The evaluation of the residual stress profile was obtained by sin 2 ψ method. The results show that the formation of the curvature arc height is proportional to the shot peening pressure, of spheres size and inversely proportional to the thickness of the sample, and that stress concentration factor is larger for samples shot peened with small balls. On final of this paper presents an additional study on micro strain and average crystallite size, which can evaluate the profile of the samples after blasting. (author)
An investigation of the residual stress characterization and relaxation in peened friction stir welded aluminum-lithium alloy joints

International Nuclear Information System (INIS)

Hatamleh, Omar; Rivero, Iris V.; Swain, Shayla E.

2009-01-01

In this investigation the residual stresses generated from friction stir welded (FSW) 2195 aluminum-lithium alloy joints were characterized. The results derived from this research revealed significant levels of tensile residual stresses at the surface and throughout the thickness of the FSW samples. Furthermore, residual stress relaxation at the surface and throughout the thickness of the samples was assessed for laser peened friction stir welded aluminum-lithium joints. To do so the samples were cycled several times at a constant amplitude load. The results indicated that most of the relaxation for the surface residual stresses took place during the first cycle of loading. Also, residual stresses relaxation throughout the thickness of the welded region of unpeened samples significantly exceeded the relaxation exhibited by the laser peened samples.
Temperature dependence of residual stress in TiC coated Mo

International Nuclear Information System (INIS)

Yoshizawa, I.; Fukutomi, M.; Kamada, K.

1984-01-01

The effects of fabrication temperature and heat treatment on the residual stress in TiC coated Mo have been studied by using X-ray diffractometry. TiC coatings on Mo single crystal substrates with (100) and (111) surfaces were carried out with the Activated Reactive Evaporation (ARE) method. It was found that all Mo substrates measured show tensile residual stresses, and their values decrease as the fabrication temperature increases from 300 to 700 0 C. On the other hand, TiC films measured showed compressive residual stresses, for both TiC/Mo(100) and TiC/Mo(111) specimens. These compressive stresses also decreased with increasing the fabrication temperature. The residual stresses measured were higher in TiC/Mo(100) than in TiC/Mo(111). It was found that the compressive stresses in as-grown TiC films change to the tensile stresses after annealing at 1700 0 C for 30 min. The preferred orientations of TiC films were observed to depend on the fabrication temperature. However, no epitaxial growth of TiC films was found as far as the present experiment was concerned. (orig.)
On machine surface to the unit event causing residual stress

International Nuclear Information System (INIS)

Arunachalama, R.M.; Mannanb, M.A.; Spowageca, A.

2005-01-01

Integrity and reduce overall costs. Within the framework of surface integrity investigations, special emphasis is given to the measurement of residual stresses because they contribute directly to premature failure of components. Since the highest residual stresses are to be found in surface layers, these deserve special attention when dealing with dynamically, heavily loaded machine parts such as gas turbine components used in aero engines. Of the many techniques available for the measurement of residual stresses, the most highly developed and widely used non-destructive method is based on X-ray diffraction (XRD). However, it is not possible to use this technique for inspection of all the components, since it is time consuming, complicated as well as expensive. In this paper, a method is being proposed that augments the XRD method but at the same time capable of inspecting all the components. A non-destructive, visual inspection technique has been developed that can correlate the characteristic features on the surface to the unit event causing the residual stress and the type of residual stress generated on the machined surface. Pictures of the machined surfaces have been taken using a digital video microscope at a magnification of 500 and the surface feature correlated to the unit event causing the residual stress. Sharp and well defined long grooves indicate that the plastic deformation is dominated by a mechanical unit event while appearance of streaks and small areas of smeared material indicate that the plastic deformation is dominated by a thermal unit event. These trends have been confirmed by measuring the residual stresses using XRD. The proposed technique is an attempt at establishing a simple methodology that would be useful to industries manufacturing aerospace and other components that require good surface integrity. (Author)
Modelling of Tool Wear and Residual Stress during Machining of AISI H13 Tool Steel

Science.gov (United States)

Outeiro, José C.; Umbrello, Domenico; Pina, José C.; Rizzuti, Stefania

2007-05-01

Residual stresses can enhance or impair the ability of a component to withstand loading conditions in service (fatigue, creep, stress corrosion cracking, etc.), depending on their nature: compressive or tensile, respectively. This poses enormous problems in structural assembly as this affects the structural integrity of the whole part. In addition, tool wear issues are of critical importance in manufacturing since these affect component quality, tool life and machining cost. Therefore, prediction and control of both tool wear and the residual stresses in machining are absolutely necessary. In this work, a two-dimensional Finite Element model using an implicit Lagrangian formulation with an automatic remeshing was applied to simulate the orthogonal cutting process of AISI H13 tool steel. To validate such model the predicted and experimentally measured chip geometry, cutting forces, temperatures, tool wear and residual stresses on the machined affected layers were compared. The proposed FE model allowed us to investigate the influence of tool geometry, cutting regime parameters and tool wear on residual stress distribution in the machined surface and subsurface of AISI H13 tool steel. The obtained results permit to conclude that in order to reduce the magnitude of surface residual stresses, the cutting speed should be increased, the uncut chip thickness (or feed) should be reduced and machining with honed tools having large cutting edge radii produce better results than chamfered tools. Moreover, increasing tool wear increases the magnitude of surface residual stresses.
Martensitic transformation and residual stresses after thermomechanical treatment of heat treatable steel 42CrMo4 (SAE 4140)

Energy Technology Data Exchange (ETDEWEB)

Weise, A. [Technische Univ. Chemnitz-Zwickau, Chemnitz (Germany). Fakultaet fuer Maschinenbau und Verfahrenstechnik; Fritsche, G. [Technische Univ. Chemnitz-Zwickau, Chemnitz (Germany). Fakultaet fuer Maschinenbau und Verfahrenstechnik

1996-01-01

The influence of thermomechanical deformation on the residual stresses caused by quenching in bar shaped specimens of heat treatable steel 42CrMo4 has been investigated using a mechanical method for determining the distribution of residual stresses of the first kind. The results obtained show that the residual stress distribution after quenching is affected by the strengthening and softening of the austenite as a result of deformation and recrystallization and the modified transformation behaviour in martensite stage. An attempt is made to discuss qualitatively the influence of these changes on the generation of residual stresses as compared to results obtained after conventional hardening. (orig.).
Martensitic transformation and residual stresses after thermomechanical treatment of heat treatable steel 42CrMo4 (SAE 4140)

International Nuclear Information System (INIS)

Weise, A.; Fritsche, G.

1996-01-01

The influence of thermomechanical deformation on the residual stresses caused by quenching in bar shaped specimens of heat treatable steel 42CrMo4 has been investigated using a mechanical method for determining the distribution of residual stresses of the first kind. The results obtained show that the residual stress distribution after quenching is affected by the strengthening and softening of the austenite as a result of deformation and recrystallization and the modified transformation behaviour in martensite stage. An attempt is made to discuss qualitatively the influence of these changes on the generation of residual stresses as compared to results obtained after conventional hardening. (orig.)
Residual stress improvement for pipe weld by means of induction heating pre-flawed pipe

International Nuclear Information System (INIS)

Umemoto, T.; Yoshida, K.; Okamoto, A.

1980-01-01

The intergranular stress corrosion cracking (IGSCC) has been found in type 304 stainless steel piping of several BWR plants. It is already well known that IGSCC is most likely to occur when three essential factors, material sensitization, high tensile stress and corrosive environment, are present. If the welding residual stress is sufficiently high (200 to approximately 400 MPa) in the inside piping surface near the welded joint, then it may be one of the biggest contributors to IGSCC. If the residual stress is reduced or reversed by some way, the IGSCC will be effectively mitigated. In this paper a method to improve the residual stress named IHSI (Induction Heating Stress Improvement) is explained. IHSI aims to improve the condition of residual stress in the inside pipe surface using the thermal stress induced by the temperature difference in pipe wall, that is produced when the pipe is heated from the outside surface by an induction heating coil and cooled on the inside surface by water simultaneously. This method becomes more attractive when it can be successfully applied to in-service piping which might have some pre-flaw. In order to verify the validity of IHSI for such piping, some experiments and calculations using finite element method were conducted. These results are mainly discussed in this paper from the view-points of residual stress, flaw behaviour during IHSI and material deterioration. (author)
Effects on Machining on Surface Residual Stress of SA 508 and Austenitic Stainless Steel

International Nuclear Information System (INIS)

Lee, Kyoung Soo; Lee, Seong Ho; Park, Chi Yong; Yang, Jun Seok; Lee, Jeong Geun; Park, Jai Hak

2011-01-01

Primary water stress corrosion cracking has occurred in dissimilar weld areas in nuclear power plants. Residual stress is a driving force in the crack. Residual stress may be generated by weld or surface machining. Residual stress due to surface machining depends on the machining method, e.g., milling, grinding, or EDM. The stress is usually distributed on or near the surface of the material. We present the measured residual stress for machining on SA 508 and austenitic stainless steels such as TP304 and F316. The residual stress can be tensile or compressive depending on the machining method. The depth and the magnitude of the residual stress depend on the material and the machining method
Calculation of residual stresses by means of a 3D numerical weld simulation

International Nuclear Information System (INIS)

Nicak, Tomas; Huemmer, Matthias

2008-01-01

The numerical weld simulation has developed very fast in recent years. The problem complexity has increased from simple 2D models to full 3D models, which can describe the entire welding process more realistically. As recent research projects indicate, a quantitative assessment of the residual stresses by means of a 3D analysis is possible. The structure integrity can be assessed based on the weld simulation results superimposed with the operating load. Moreover, to support the qualification of welded components parametric studies for optimization of the residual stress distribution in the weld region can be performed. In this paper a full 3D numerical weld simulation for a man-hole drainage nozzle in a steam generator will be presented. The residual stresses are calculated by means of an uncoupled transient thermal and mechanical FE analysis. The paper will present a robust procedure allowing reasonable predictions of the residual stresses for complex structures in industrial practice. (authors)
Residual stresses associated with the hydraulic expansion of steam generator tubing into tubesheets

International Nuclear Information System (INIS)

Middlebrooks, W.B.; Harrod, D.L.; Gold, R.E.

1991-01-01

Westinghouse has used three different processes for the full depth expansion of tubes into the tube sheets of recirculating nuclear steam generators: mechanical rolling, explosive expansion and hydraulic expansion. Each process aims at expanding tubes tightly to tube sheets, leaving the smallest possible secondary side crevice depth, and minimizing the residual stress in the expanded tubes, all for the purpose of mitigating the effect of corrosion phenomena. The hydraulic expansion process was qualified and has been implemented since 1978, and more than 1.1 million tube ends have been hydraulically expanded into production units. In this paper, the results of the recent analytical studies related to the residual stress in the expanded tubes are summarized. The method of hydraulic expansion is explained, and some important parameters are given. Finite element method, theoretical incremental analysis, tube sheet yielding and residual stress, contact pressure, sensitivity analysis and temperature effect in the central region of tube sheets, and the residual stress in the transition zone are described. (K.I.)
Experimental evaluation of residual stresses produced by plain dents in pipelines

Energy Technology Data Exchange (ETDEWEB)

Pascotto, Jorge [PETROBRAS Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil); Marques, Altino; Fonseca, Maria Cindra [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)

2009-07-01

A dent means a permanent plastic deformation of the circular cross-section of the pipe. Dents are potentially danger for structural integrity of onshore and offshore pipelines, because it causes a local stress and strain concentration. It is also expected that residual stresses are introduced by the non-uniform plastic deformation. A plain dent is a dent which causes a smooth change in the curvature of the pipe wall that contains no wall thickness reductions (such as a gouge or a crack) or other defects or imperfections (such as a weld). This work presents an experimental evaluation of residual stresses intensification due to plain dents introduced through the same indentation process, in samples made of the same steel line pipe, commonly used in the pipeline industry. The residual stresses were measured in the longitudinal and circumferential directions in preselected points by X-ray diffraction technique, before indentation. After the samples have been dented, the residual stresses were measured once more at the same points, for comparison. All samples presented a similar behavior of the residual stresses due to induced plain dents, and the X-ray diffraction technique shows itself as an efficient methodology of stress measurement in pipelines. (author)
Thermal Aging Effects on Residual Stress and Residual Strain Distribution on Heat Affected Zone of Alloy 600 in Dissimilar Metal Weld

Energy Technology Data Exchange (ETDEWEB)

Ham, Junhyuk; Choi, Kyoung Joon; Kim, Ji Hyun [UNIST, Ulsan (Korea, Republic of)

2016-10-15

Dissimilar metal weld (DMW), consisting of Alloy 600, Alloy 182, and A508 Gr.3, has been widely used as a joining material of the reactor pressure vessel penetration nozzle and the steam generator tubing for pressurized water reactors (PWR) because of its good mechanical strength, thermal conductivity, and corrosion resistance. Residual tensile stress is mainly nominated as a cause of SCC in light water reactors by IAEA report. So, to relax the residual stress, post-weld heat treatment is required after manufacturing process such as welding. However, thermal treatment has a great effect on the microstructure and the chromium depletion profile on Alloy 600, so called sensitization. By this reason, HAZ on Alloy 600 is critical to crack. According to G.A. Young et al., Crack growth rates (CGR) in the Alloy 600 HAZ were about 30 times faster than those in the Alloy 600 base metal tested under the same conditions. And according to Z.P. Lu et al., CGR in the Alloy 600 HAZ can be more than 20 times higher than that in its base metal. There are some methods to measure the exact value of residual stress on the material surface. The most common way is X-ray diffraction method (XRD). The principle of XRD is based on lattice strains and depends on the changes in the spacing of the atomic planes in material. And there is a computer simulation method to estimate residual stress distribution which is called ANSYS. This study was conducted to investigate how thermal aging affects residual stress and residual strain distribution of Alloy 600 HAZ. Following conclusions can be drawn from this study. According to preceding researches and this study, both the relaxation of residual stress and the change of residual strain follow as similar way, spreading out from concentrated region. The result of Vickers micro-hardness tester shows that tensile residual stresses are distributed broadly on the material aged by 15 years. Therefore, HT400{sub Y}15 material is weakest state for PWSCC. The
Effect of residual stress induced by cold expansion on fatigue crack ...

African Journals Online (AJOL)

Fatigue life and fatigue crack growth rate are controlled by stress ratio, stress level, orientation of crack, temper-ature, residual stress, corrosion, etc. The effects of residual stress on fatigue crack growth in aluminium (Al) alloy 2024-T351 by Mode I crack were investigated by applying constant amplitude cycles based on ...
Diffraction measurements of residual stress in titanium matrix composites

International Nuclear Information System (INIS)

James, M.R.; Bourke, M.A.; Goldstone, J.A.; Lawson, A.C.

1993-01-01

Metal matrix composites develop residual strains after consolidation due to the thermal expansion mismatch between the reinforcement fiber and the matrix. X-ray and neutron diffraction measured values for the longitudinal residual stress in the matrix of four titanium MMCs are reported. For thick composites (> 6 plies) the surface stress measured by x-ray diffraction matches that determined by neutron diffraction and therefore represents the stress in the bulk region consisting of the fibers and matrix. For thin sheet composites, the surface values are lower than in the interior and increase as the outer rows of fibers are approached. While a rationale for the behavior in the thin sheet has yet to be developed, accounting for composite thickness is important when using x-ray measured values to validate analytic and finite element calculations of the residual stress state
Residual stress measurement in worked and heat treated steel by X-ray diffractometry

International Nuclear Information System (INIS)

Sinha, V.K.; Godaba, V.S.

2008-01-01

Investigations were made for residual stress measurement by X-ray diffractometry in the 1.14% C, 0.46% Mn, 0.16% Si, 0.11% S and 0.04% P steel samples subjected to inhomogeneous plastic deformation (cold upsetting in the range 7.7-21%), thermal gradient (quenching from 630 deg. C) and phase transformation (quenching from 850 deg. C), respectively. The results indicated that compressive residual stress at the surface increased in the samples with increasing deformation acquiring values in the range, -269.5 MPa to -374.7 MPa. In the samples quenched from 630 deg. C, the thermal stresses acquired increasing values in the range -83.9 MPa (compressive) to -188.1 MPa (compressive) with increased cooling rate. In the samples quenched from 850 deg. C, volume increase on account of austenite to martensite phase transformation ultimately dominated the thermal contraction resulting in residual stress at the surface from -329.3 MPa (compressive) to +61.7 MPa (tensile)
Reduction method for residual stress of welded joint using harmonic vibrational load

International Nuclear Information System (INIS)

Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro; Hirai, Seiji

2007-01-01

Welding is widely used for construction of many structures. Since welding is a process using locally given heat, residual stress is generated near the bead. Tensile residual stress degrades fatigue strength. Some reduction methods of residual stress have been presented and, for example, heat treatment and shot peening are practically used. However, those methods need special tools and are time consuming. In this paper, a new method for reduction of residual stress using harmonic vibrational load during welding is proposed. The proposed method is examined experimentally for some conditions. Two thin plates are supported on the supporting device and butt-welded using an automatic CO 2 gas shielded arc welding machine. Residual stress in the direction of the bead is measured by using a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. First, the welding of rolled steel for general structure for some excitation frequencies is examined. Specimens are welded along the groove on both sides. For all frequencies, tensile residual stress near the bead is significantly reduced. Second, welding of the specimen made of high tensile strength steel is examined. In this case, tensile residual stress near the bead is also reduced. Finally, the proposed method is examined by an analytical method. An analytical model which consists of mass and preloaded springs with elasto-plastic characteristic is used. Reduction of residual stress is demonstrated using this model

On Taylor-Series Approximations of Residual Stress

Science.gov (United States)

Pruett, C. David

1999-01-01

Although subgrid-scale models of similarity type are insufficiently dissipative for practical applications to large-eddy simulation, in recently published a priori analyses, they perform remarkably well in the sense of correlating highly against exact residual stresses. Here, Taylor-series expansions of residual stress are exploited to explain the observed behavior and "success" of similarity models. Until very recently, little attention has been given to issues related to the convergence of such expansions. Here, we re-express the convergence criterion of Vasilyev [J. Comput. Phys., 146 (1998)] in terms of the transfer function and the wavenumber cutoff of the grid filter.
A wafer mapping technique for residual stress in surface micromachined films

International Nuclear Information System (INIS)

Schiavone, G; Murray, J; Smith, S; Walton, A J; Desmulliez, M P Y; Mount, A R

2016-01-01

The design of MEMS devices employing movable structures is crucially dependant on the mechanical behaviour of the deposited materials. It is therefore important to be able to fully characterize the micromachined films and predict with confidence the mechanical properties of patterned structures. This paper presents a characterization technique that enables the residual stress in MEMS films to be mapped at the wafer level by using microstructures released by surface micromachining. These dedicated MEMS test structures and the associated measurement techniques are used to extract localized information on the strain and Young’s modulus of the film under investigation. The residual stress is then determined by numerically coupling this data with a finite element analysis of the structure. This paper illustrates the measurement routine and demonstrates it with a case study using electrochemically deposited alloys of nickel and iron, particularly prone to develop high levels of residual stress. The results show that the technique enables wafer mapping of film non-uniformities and identifies wafer-to-wafer differences. A comparison between the results obtained from the mapping technique and conventional wafer bow measurements highlights the benefits of using a procedure tailored to films that are non-uniform, patterned and surface-micromachined, as opposed to simple standard stress extraction methods. The presented technique reveals detailed information that is generally unexplored when using conventional stress extraction methods such as wafer bow measurements. (paper)
Residual Stress Developed During the Cure of Thermosetting Polymers: Optimizing Cure Schedule to Minimize Stress.

Energy Technology Data Exchange (ETDEWEB)

Kropka, Jamie Michael; Stavig, Mark E.; Jaramillo, Rex

2016-06-01

When thermosetting polymers are used to bond or encapsulate electrical, mechanical or optical assemblies, residual stress, which often affects the performance and/or reliability of these devices, develops within the structure. The Thin-Disk-on-Cylinder structural response test is demonstrated as a powerful tool to design epoxy encapsulant cure schedules to reduce residual stress, even when all the details of the material evolution during cure are not explicitly known. The test's ability to (1) distinguish between cohesive and adhesive failure modes and (2) demonstrate methodologies to eliminate failure and reduce residual stress, make choices of cure schedules that optimize stress in the encapsulant unambiguous. For the 828/DEA/GMB material in the Thin-Disk-on-Cylinder geometry, the stress associated with cure is significant and outweighs that associated with cool down from the final cure temperature to room temperature (for measured lid strain, Scure I > I I e+h erma * II) * The difference between the final cure temperature and 1 1 -- the temperature at which the material gels, Tf-T ge i, was demonstrated to be a primary factor in determining the residual stress associated with cure. Increasing T f -T ge i leads to a reduction in cure stress that is described as being associated with balancing some of the 828/DEA/GMB cure shrinkage with thermal expansion. The ability to tune residual stress associated with cure by controlling T f -T ge i would be anticipated to translate to other thermosetting encapsulation materials, but the times and temperatures appropriate for a given material may vary widely.
Coping with residual stresses in the integrity assessment of an as-welded repair

International Nuclear Information System (INIS)

Knee, N.

1989-11-01

One of a series of large scale tests on pressure vessels is described, in which a defect was deliberately introduced into an as-welded (i.e. not stress relieved) repair weld. The behaviour of the vessel during pressurization to failure was carefully monitored and the actual performance compared with theoretical predictions. The influence of residual welding stresses on ductile crack growth from pre-existing defects is discussed in the light of the results of this test and of previous tests in the series. The tests have confirmed that residual stresses can exert a significant effect on the growth of fatigue cracks. However, in tests for which the failure mechanism is predominantly controlled by collapse of the remaining ligament, the development of plasticity during pressurization to failure will tend to remove any local residual stresses. (author)
Finite Element Simulation of Shot Peening: Prediction of Residual Stresses and Surface Roughness

Science.gov (United States)

Gariépy, Alexandre; Perron, Claude; Bocher, Philippe; Lévesque, Martin

Shot peening is a surface treatment that consists of bombarding a ductile surface with numerous small and hard particles. Each impact creates localized plastic strains that permanently stretch the surface. Since the underlying material constrains this stretching, compressive residual stresses are generated near the surface. This process is commonly used in the automotive and aerospace industries to improve fatigue life. Finite element analyses can be used to predict residual stress profiles and surface roughness created by shot peening. This study investigates further the parameters and capabilities of a random impact model by evaluating the representative volume element and the calculated stress distribution. Using an isotropic-kinematic hardening constitutive law to describe the behaviour of AA2024-T351 aluminium alloy, promising results were achieved in terms of residual stresses.
Accounting for the residual stress effects on the creep deformation of channel tubes

International Nuclear Information System (INIS)

Knizhnikov, Yu.N.; Platonov, P.A.; Ul'yanov, A.I.

1985-01-01

The effect of the first kind residual stresses arising in the walls of the zirconium base alloy fules in the process of fabrication on the RBMK type reactor channel tube creep is investigated. Models for calculation of the reactor component creep with account for the relaxation of residual stresses distributed by the wall thickness as well as the radiation and temperature fields are developed. On the basis of the analysis of the data obtained it is concluded that the effect of the residual stresses on the RBMK channel tube deformation for a long-term operation is negligible. But for the short-term fests the results can be noticeably distorted by this factor. The role of internal stresses can also manifest when determining the deformation of radiation elongation of the zirconium base alloy samples
Analysis of shot-peening and residual stress relaxation in the nickel-based superalloy RR1000

International Nuclear Information System (INIS)

Foss, B.J.; Gray, S.; Hardy, M.C.; Stekovic, S.; McPhail, D.S.; Shollock, B.A.

2013-01-01

This work assesses the residual stress relaxation of the nickel-based alloy RR1000 due to thermal exposure and dwell-fatigue loading. A number of different characterization methods, including X-ray residual stress analysis, electron back-scattered diffraction, microhardness testing and focused ion beam secondary electron imaging, contributed to a detailed study of the shot-peened region. Thermal exposure at 700 °C resulted in a large reduction in the residual stresses and work-hardening effects in the alloy, but the subsurface remained in a beneficial compressive state. Oxidizing environments caused recrystallization in the near surface, but did not affect the residual stress-relaxation behaviour. Dwell-fatigue loading caused the residual stresses to return to approximately zero at nearly all depths. This work forms part of an ongoing investigation to determine the effects of shot-peening in this alloy with the motivation to improve the fatigue and oxidation resistance at 700 °C
Relation between psi-splitting and microscopic residual shear stresses in x-ray stress measurement on uni-directionally deformed layers

International Nuclear Information System (INIS)

Hanabusa, Takao; Fujiwara, Haruo

1982-01-01

The psi-splitting behaviors were investigated for the ground and the milled surface layers of both iron and high speed steel in order to find out the relation among microscopic residual shear stresses. For the high speed steel, the X-ray elastic constants and the residual strains were measured on the carbide phase as well as on the matrix phase. It was clarified that the psi-splitting was caused by a combination of the selective nature of X-ray diffractions and the microscopic residual shear stresses within the interior of cells and the carbide particles. The volume fraction occupied by the cell walls and the residual shear stresses sustained by them were estimated from the equilibrium condition of the microscopic residual shear stresses. The distributions of residual stresses over the deformed layers indicate that the thermal effect is dominant in grinding and the mechanical effect is dominant in milling for forming residual stresses. (author)
Fatique crack propagation in bimetallic welds influence of residual stresses and metallurgical look

International Nuclear Information System (INIS)

Zahouane, A.I.

1988-06-01

Generally, in nuclear power plants, many components made of austenitic stainless steels are very often replaced by low alloyed steels cladded with stainless steels, mainly for economical reasons. Due to cracks existing at the limit of the two kinds of steel, it is interesting to try to understand how they appear. Residual stresses are generally identified as one of the factors which act to produce these cracks. Measurements of such residual stresses have been performed, using the hole drilling method (drilling of a hole at the center of a gauge roset stuck at the surface of the material). Owing to the obtained results, it is possible to explain the decrease in the crack propagation rate observed, on fatigue crack growth test performed on specimens taken in the transition ferritic/austenitic zone. The stress intensity factor due to the residual stresses is valued by weight function method. It is possible to explain qualitatively the phenomena observed under cyclic loading when using the obtained value of this stress intensity factor. A more quantitative approach based on the use of an efficient stress intensity factor, allow to better describe the effect of residual stresses on the fatigue crack propagation in bimetallic welds [fr
Creep Modeling in a Composite Rotating Disc with Thickness Variation in Presence of Residual Stress

Directory of Open Access Journals (Sweden)

Vandana Gupta

2012-01-01

Full Text Available Steady-state creep response in a rotating disc made of Al-SiC (particle composite having linearly varying thickness has been carried out using isotropic/anisotropic Hoffman yield criterion and results are compared with those using von Mises yield criterion/Hill's criterion ignoring difference in yield stresses. The steady-state creep behavior has been described by Sherby's creep law. The material parameters characterizing difference in yield stresses have been used from the available experimental results in literature. Stress and strain rate distributions developed due to rotation have been calculated. It is concluded that the stress and strain distributions got affected from the thermal residual stress in an isotropic/anisotropic rotating disc, although the effect of residual stress on creep behavior in an anisotropic rotating disc is observed to be lower than those observed in an isotropic disc. Thus, the presence of residual stress in composite rotating disc with varying thickness needs attention for designing a disc.
INTERFACE RESIDUAL STRESSES IN DENTAL ZIRCONIA USING LAUE MICRO-DIFFRACTION

International Nuclear Information System (INIS)

Bale, H. A.; Tamura, N.; Coelho, P.G.; Hanan, J. C.

2009-01-01

Due to their aesthetic value and high compressive strength, dentists have recently employed ceramics for restoration materials. Among the ceramic materials, zirconia provides high toughness and crack resistant characteristics. Residual stresses develop in processing due to factors including grain anisotropy and thermal coefficient mismatch. In the present study, polychromatic X-ray (Laue) micro-diffraction provided grain orientation and residual stresses on a clinically relevant zirconia model ceramic disk. A 0.5 mm x 0.024 mm region on zirconia was examined on a 500 nm scale for residual stresses using a focused poly-chromatic synchrotron X-ray beam. Large stresses ranging from - to + 1GPa were observed at some grains. On average, the method suggests a relatively small compressive stress at the surface between 47 and 75 MPa depending on direction
Numerical simulation of residual stress in piping components at Framatome-ANP

International Nuclear Information System (INIS)

Gilies, P.; Franco, C.; Cipiere, M.-F.; Ould, P.

2005-01-01

Numerous manufacturing processes induce residual stresses and distortions in piping components and associated welds: quenching of cast pipings, machining and welding. In Pressurized Water Reactors, most of the components have a large thickness for sustaining pressure and distortions are a minor source of concern. This is not the case for residual stresses which may have a strong influence on several type of damage such as fatigue, corrosion, brittle fracture. In low toughness components, residual stress fields may contribute to ductile tearing initiation. These potential damages are mitigated after welding by stress relief heat treatment, which is applied in a systematic manner to ferritic components of the primary system in nuclear reactors. This treatment is not applied on austenitic piping for which the heat treatment temperature is limited due to the risk of sensitization and residual stresses are difficult to eliminate completely. Since on site measurements are costly and difficult to perform, numerical simulation appears to be an attractive tool for estimating residual stress distributions. Framatome-ANP is working on modelling manufacturing processes with that purpose in mind. This paper presents three kinds of applications illustrating efforts on welding, quenching and machining simulation. First a comparison is shown between computations and measurements of residual stress induced by welding of a dissimilar weld metal junction. Then numerical simulations of quenching of a cast stainless steel nozzle are presented. Finally quenching followed by machining and grinding of this cast component are considered in a full simulation of the manufacturing process. Computed distortions and residual stresses are compared with experimental measurements at different stages of the manufacturing process. (authors)
Residual Stress Analysis of Severe Plastic Deformed Materials using the Finite Element Method and the Neutron Diffraction Method

International Nuclear Information System (INIS)

Kang, Mi Hyun; Seong, Back Suck; Kim, Hyoung Seop

2009-01-01

Severe plastic deformation (SPD) is one of the most promising top-down techniques, moving towards industrialization to fabricate bulk ultrafine grain materials. The strain distribution and deformation behavior during the ECAP (equal channel angular pressing), influenced by tool angles, friction and material behavior, was studied through experimental and numerical analyses. The residual stress of work piece which was straight before ECAP produces many serious problems in the next processing e.g. input of the work piece for the next ECAP. The bent work piece needs additional straightening or surface polishing even if the amount of bending is small, and residual stress need to be released before service applications. Residual stress, particularly tensile residual stress can be a very important factor in affecting the reliability and integrity of working parts. The formation of tensile residual stress may result in initiation of fatigue cracks, stress corrosion cracking, or other types of fracture. Hence, residual stress and resulting bending need to be controlled during ECAP. Thus, in current study the bending behavior and the residual stress of the work piece in ECAP are analyzed through experimental and finite element analyses by considering the effects of material, geometric, and processing parameters individually. The stress states in the ECAP processed work piece were measured by the non-destructive way using neutron diffraction. Efforts were made to suggest the alternate routes to reduce the residual stress and bending of work piece in ECAP
The influence of punching process on residual stress and magnetic domain structure of non-oriented silicon steel

International Nuclear Information System (INIS)

Cao, Hongzhi; Hao, Linpo; Yi, Jingwen; Zhang, Xianglin; Luo, Zhonghan; Chen, Shenglin; Li, Rongfeng

2016-01-01

The main purpose of this paper is to investigate the influence of punching process on residual stress and magnetic domain structure. The residual stress in non-oriented silicon steel after punching process was measured by nanoindentation. The maximum depth was kept constant as 300 nm during nanoindentation. The material around indentation region exhibited no significant pile-up deformation. The calculation of residual stress was based on the Suresh theoretical model. Our experimental results show that residual compressive stress was generated around the sheared edge after punching. The width of residual stress affected zone by punching was around 0.4–0.5 mm. After annealing treatment, the residual stress was significantly decreased. Magnetic domain structure was observed according to the Bitter method. The un-annealed sample exhibited complicated domain patterns, and the widths of the magnetic domains varied between 3 µm and 8 µm. Most of the domain patterns of the annealed sample were 180°-domains and 90°-domains, and the widths of the domains decreased to 1–3 µm. - Highlights: • The residual stress distribution on sheared edge was measured. • The residual compressive stress was generated around the sheared edge. • The width of residual stress affected zone was about 0.4–0.5 mm. • The shape and width of the domain structure would be changed by annealing.
Eddy Current Nondestructive Residual Stress Assessment in Shot-Peened Nickel-Base Superalloys

International Nuclear Information System (INIS)

Blodgett, M.P.; Yu, F.; Nagy, P.B.

2005-01-01

Shot peening and other mechanical surface enhancement methods improve the fatigue resistance and foreign-object damage tolerance of metallic components by introducing beneficial near-surface compressive residual stresses and hardening the surface. However, the fatigue life improvement gained via surface enhancement is not explicitly accounted for in current engine component life prediction models because of the lack of accurate and reliable nondestructive methods that could verify the presence of compressive near-surface residual stresses in shot-peened hardware. In light of its frequency-dependent penetration depth, the measurement of eddy current conductivity has been suggested as a possible means to allow the nondestructive evaluation of subsurface residual stresses in surface-treated components. This technique is based on the so-called piezoresistivity effect, i.e., the stress-dependence of electrical resistivity. We found that, in contrast with most other materials, surface-treated nickel-base superalloys exhibit an apparent increase in electrical conductivity at increasing inspection frequencies, i.e., at decreasing penetration depths. Experimental results are presented to illustrate that the excess frequency-dependent apparent eddy current conductivity of shot-peened nickel-base superalloys can be used to estimate the absolute level and penetration depth of the compressive residual stress layer both before and after partial thermal relaxation
Effect of the weld groove shape and pass number on residual stresses in butt-welded pipes

International Nuclear Information System (INIS)

Sattari-Far, I.; Farahani, M.R.

2009-01-01

This study used finite element techniques to analyze the thermo-mechanical behaviour and residual stresses in butt-welded pipes. The residual stresses were also measured in some welds by using the Hole-Drilling method. The results of the finite element analysis were compared with experimentally measured data to evaluate the accuracy of the finite element modelling. Based on this study, a finite element modelling procedure with reasonable accuracy was developed. The developed FE modelling was used to study the effects of weld groove shape and weld pass number on welding residual stresses in butt-welded pipes. The hoop and axial residual stresses in pipe joints of 6 and 10 mm thickness of different groove shapes and pass number were studied. It is shown that these two parameters may have significant effects on magnitude and distribution of residual stresses in welded pipes.
Residual stress development and relief in high strength aluminium alloys using standard and retrogression thermal treatments

OpenAIRE

Robinson, J.S; Tanner, D.A

2003-01-01

peer-reviewed Residual stresses develop in the aluminium alloy 7010 when the material is quenched from the solution heat treatment temperature. Residual stress measurements have been made using the X-ray diffraction technique and a longitudinal split sawcut method to determine the magnitude of residual stress that develops in specimens sectioned from large open die forgings as a result of (a) quenching these specimens into water at different temperatures, and (b) cold water quenching from ...
Residual stresses measurement by using ring-core method and 3D digital image correlation technique

International Nuclear Information System (INIS)

Hu, Zhenxing; Xie, Huimin; Zhu, Jianguo; Wang, Huaixi; Lu, Jian

2013-01-01

Ring-core method/three-dimensional digital image correlation (3D DIC) residual stresses measurement is proposed. Ring-core cutting is a mechanical stress relief method, and combining with 3D DIC system the deformation of the specimen surface can be measured. An optimization iteration method is proposed to obtain the residual stress and rigid-body motion. The method has the ability to cut an annular trench at a different location out of the field of view. A compression test is carried out to demonstrate how residual stress is determined by using 3D DIC system and outfield measurement. The results determined by the approach are in good agreement with the theoretical value. Ring-core/3D DIC has shown its robustness to determine residual stress and can be extended to application in the engineering field. (paper)
Fatigue life estimation of welded components considering welding residual stress relaxation and its mean stress effect

International Nuclear Information System (INIS)

Han, Seung Ho; Han, Jeong Woo; Shin, Byung Chun; Kim, Jae Hoon

2003-01-01

The fatigue life of welded joints is sensitive to welding residual stress and complexity of their geometric shapes. To predict the fatigue life more reasonably, the effects of welding residual stress and its relaxation on their fatigue strengths should be considered quantitatively, which are often regarded to be equivalent to the effects of mean stresses by external loads. The hot-spot stress concept should be also adopted which can reduce the dependence of fatigue strengths for various welding details. Considering the factors mentioned above, a fatigue life prediction model using the modified Goodman's diagram was proposed. In this model, an equivalent stress was introduced which is composed of the mean stress based on the hot-spot stress concept and the relaxed welding residual stress. From the verification of the proposed model to real welding details, it is proved that this model can be applied to predict reasonably their fatigue lives
Experimental analysis of residual stresses in pre-straightened SAE 1045 steel

Energy Technology Data Exchange (ETDEWEB)

Diehl, Carla Adriana Theis Soares; Rocha, Alexandre da Silva, E-mail: carla.adriana@ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Laboratorio de Formacao de Metais; Epp, Jérémy; Zoch, Hans-Werner [Stiftung Institut für Werkstofftechnik IWT, University of Bremen (Germany)

2017-11-15

This paper aims at analyzing the effects of the roller pre-straightening of wire-rods on residual stress distributions in SAE 1045 steel bars. The combined drawing process is used in industrial production of bars in order to obtain a good surface quality and improved mechanical properties complying with specifications of the final products. In this process, prior to the drawing step, a roller straightening of the steel wire-rod is essential, because it provides the minimum straightness necessary for drawing. Metallographic analysis and hardness test were done for selected samples after different processing steps. Also, residual stress analysis of pre-straightened wire-rods by X-ray diffraction and neutron diffraction were carried out. The hardness tests show higher values near the surface and lower in the center of the wire-rod. Besides, the residual stresses results show a big inhomogeneity from one peripheral position to another and also in the evaluated cross section. (author)

Experimental analysis of residual stresses in pre-straightened SAE 1045 steel

International Nuclear Information System (INIS)

Diehl, Carla Adriana Theis Soares; Rocha, Alexandre da Silva

2017-01-01

This paper aims at analyzing the effects of the roller pre-straightening of wire-rods on residual stress distributions in SAE 1045 steel bars. The combined drawing process is used in industrial production of bars in order to obtain a good surface quality and improved mechanical properties complying with specifications of the final products. In this process, prior to the drawing step, a roller straightening of the steel wire-rod is essential, because it provides the minimum straightness necessary for drawing. Metallographic analysis and hardness test were done for selected samples after different processing steps. Also, residual stress analysis of pre-straightened wire-rods by X-ray diffraction and neutron diffraction were carried out. The hardness tests show higher values near the surface and lower in the center of the wire-rod. Besides, the residual stresses results show a big inhomogeneity from one peripheral position to another and also in the evaluated cross section. (author)
Viscoelastic finite element analysis of residual stresses in porcelain-veneered zirconia dental crowns.

Science.gov (United States)

Kim, Jeongho; Dhital, Sukirti; Zhivago, Paul; Kaizer, Marina R; Zhang, Yu

2018-06-01

The main problem of porcelain-veneered zirconia (PVZ) dental restorations is chipping and delamination of veneering porcelain owing to the development of deleterious residual stresses during the cooling phase of veneer firing. The aim of this study is to elucidate the effects of cooling rate, thermal contraction coefficient and elastic modulus on residual stresses developed in PVZ dental crowns using viscoelastic finite element methods (VFEM). A three-dimensional VFEM model has been developed to predict residual stresses in PVZ structures using ABAQUS finite element software and user subroutines. First, the newly established model was validated with experimentally measured residual stress profiles using Vickers indentation on flat PVZ specimens. An excellent agreement between the model prediction and experimental data was found. Then, the model was used to predict residual stresses in more complex anatomically-correct crown systems. Two PVZ crown systems with different thermal contraction coefficients and porcelain moduli were studied: VM9/Y-TZP and LAVA/Y-TZP. A sequential dual-step finite element analysis was performed: heat transfer analysis and viscoelastic stress analysis. Controlled and bench convection cooling rates were simulated by applying different convective heat transfer coefficients 1.7E-5 W/mm 2 °C (controlled cooling) and 0.6E-4 W/mm 2 °C (bench cooling) on the crown surfaces exposed to the air. Rigorous viscoelastic finite element analysis revealed that controlled cooling results in lower maximum stresses in both veneer and core layers for the two PVZ systems relative to bench cooling. Better compatibility of thermal contraction coefficients between porcelain and zirconia and a lower porcelain modulus reduce residual stresses in both layers. Copyright © 2018 Elsevier Ltd. All rights reserved.
Quantification of Residual Stress from Photonic Signatures of Fused Silica

Science.gov (United States)

Cramer, K. Elliott; Hayward, Maurice; Yost, William E.

2013-01-01

A commercially available grey-field polariscope (GFP) instrument for photoelastic examination is used to assess impact damage inflicted upon the outer-most pane of Space Shuttle windows made from fused silica. A method and apparatus for calibration of the stress-optic coefficient using four-point bending is discussed. The results are validated on known material (acrylic) and are found to agree with literature values to within 6%. The calibration procedure is then applied to fused-silica specimens and the stress-optic coefficient is determined to be 2.43 +/- 0.54 x 10(exp -12)/Pa. Fused silica specimens containing impacts artificially made at NASA's Hypervelocity Impact Technology Facility (HIT-F), to simulate damage typical during space flight, are examined. The damage sites are cored from fused silica window carcasses and examined with the GFP. The calibrated GFP measurements of residual stress patterns surrounding the damage sites are presented. Keywords: Glass, fused silica, photoelasticity, residual stress
Residual Stresses in SAVY 4000 and Hagan Container Bodies

Energy Technology Data Exchange (ETDEWEB)

Stroud, Mary Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hill, Mary Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tokash, Justin Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Forsyth, Robert Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyer, Holden Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-11-02

Chloride-induced stress corrosion cracking (SCC) has been investigated as a potential failure mechanism for the SAVY 4000 and the Hagan containers used to store plutonium-bearing materials at Los Alamos National Laboratory. This report discusses the regions of the container bodies most susceptible to SCC and the magnitude of the residual stresses in those regions. Boiling MgCl2 testing indicated that for both containers the region near the top weld was most susceptible to SCC. The Hagan showed through wall cracking after 22-24 hours of exposure both parallel (axial stresses) and perpendicular (hoop stresses) to the weld. The SAVY 4000 container showed significant cracking above and below the weld after 47 hours of exposure but there was no visual evidence of a through wall crack and the cracks did not leak water. Two through wall holes formed in the bottom of the SAVY 4000 container after 44-46 hours of exposure. For both containers, average “through wall” residual stresses were determined from hole drilling data 4 mm below the weld. In the Hagan body, average tensile hoop stresses were 194 MPa and average compressive axial stresses were -120 MPa. In the SAVY 4000 body, average compressive hoop stresses were 11 MPa and average tensile axial stresses were 25 MPa. Results suggest that because the Hagan container exhibited through wall cracking in a shorter time in boiling MgCl2 and had the higher average tensile stress, 194 MPa hoop stress, it is more susceptible to SCC than the SAVY 4000 container.
Residual stress distribution in carbon steel pipe welded joint measured by neutron diffraction

International Nuclear Information System (INIS)

Hayashi, Makoto; Ishiwata, Masayuki; Morii, Yukio; Minakawa, Nobuaki

2000-01-01

In order to estimate crack growth behavior of fatigue and stress corrosion cracking in pipes, the residual stress distribution near the pipe weld region has to be measured through the wall thickness. Since the penetration depth of neutron is deep enough to pass through the thick pipe wall, the neutron diffraction technique for the residual stress measurement is effective for this purpose. At the first step the residual stress distribution near the weld region in a butt-welded carbon steel pipe was measured by the neutron diffraction. Significant stresses extended only to a distance of 30 mm from the center of the weld. The major tensile stresses occurred in the hoop direction in the fusion and heat affected zones of the weldment, and they attained a level greater than 200 MPa through the thickness. While the axial residual stress at the inside surface was 50 MPa, the stress at the outside surface was -100 MPa. The comparison of residual stress distributions measured by the neutron diffraction, the X-ray diffraction and the strain gauge method reveals that the neutron diffraction is the most effective for measuring the residual stress inside the structural components. (author)
Simulation of residual stresses and deformations in electron beam-welded copper canisters

International Nuclear Information System (INIS)

Aronen, A.; Leikko, J.; Taskinen, P.; Karvinen, R.

2013-07-01

This report presents the modelling of residual stresses and deformations of an EB-welded copper canister. Two different mock-up lengths are modelled with the Abaqus FEA program, and the similarity of those results is studied. Canister mock-ups of 450 mm and 915 mm were chosen for the test cases. The heat treatment results presented in Taskinen 2009 are used as input data for the mechanical model. For the mechanical analysis some simplifications were made to the model. The contact surface between pipe and lid is assumed to be tied and support from the bottom surface is provided with four support points. Results show that, due to the similarity of 450 mm and 915 mm canisters, the short mock-up can be used to predict the stresses and deformation on a full-length canister (5000 mm). The similarity of the temperature fields has already been shown in the previous reports (Taskinen 2009). The main result in the deformation is the shape of the canister in the residual state. The top of the canister tries to shrink, resulting in the lid buckling inwards. The deformation of the lid of the canister is about 2.2 mm at the centre of the lid. The main results in the stresses are the stress level on the surface, the deviation of stresses over the circle and the stresses near the welding. On the surface there are areas where the circumferential stress is at tension. However, radial and axial stresses are usually in compression on the surface. The deviation of the stress level over the circle is quite small, except in the overlap area and near it. The residual stresses from 0 deg C to 45 deg C change remarkably, but over the rest of the area the stresses are more constant. Near the welding the stresses on the top surface are in compression, but in the centre of the welding the stresses are in tension. In the modelling, the possibility of calculating a mechanical model with the contact surface between pipe and lid, so that they could be separated during the welding, was also tested
Simulation of residual stresses and deformations in electron beam-welded copper canisters

Energy Technology Data Exchange (ETDEWEB)

Aronen, A.; Leikko, J.; Taskinen, P.; Karvinen, R. [Tampere Univ. of Technology (Finland)

2013-07-15

This report presents the modelling of residual stresses and deformations of an EB-welded copper canister. Two different mock-up lengths are modelled with the Abaqus FEA program, and the similarity of those results is studied. Canister mock-ups of 450 mm and 915 mm were chosen for the test cases. The heat treatment results presented in Taskinen 2009 are used as input data for the mechanical model. For the mechanical analysis some simplifications were made to the model. The contact surface between pipe and lid is assumed to be tied and support from the bottom surface is provided with four support points. Results show that, due to the similarity of 450 mm and 915 mm canisters, the short mock-up can be used to predict the stresses and deformation on a full-length canister (5000 mm). The similarity of the temperature fields has already been shown in the previous reports (Taskinen 2009). The main result in the deformation is the shape of the canister in the residual state. The top of the canister tries to shrink, resulting in the lid buckling inwards. The deformation of the lid of the canister is about 2.2 mm at the centre of the lid. The main results in the stresses are the stress level on the surface, the deviation of stresses over the circle and the stresses near the welding. On the surface there are areas where the circumferential stress is at tension. However, radial and axial stresses are usually in compression on the surface. The deviation of the stress level over the circle is quite small, except in the overlap area and near it. The residual stresses from 0 deg C to 45 deg C change remarkably, but over the rest of the area the stresses are more constant. Near the welding the stresses on the top surface are in compression, but in the centre of the welding the stresses are in tension. In the modelling, the possibility of calculating a mechanical model with the contact surface between pipe and lid, so that they could be separated during the welding, was also tested
Effect of texture and grain size on the residual stress of nanocrystalline thin films

Science.gov (United States)

Cao, Lei; Sengupta, Arkaprabha; Pantuso, Daniel; Koslowski, Marisol

2017-10-01

Residual stresses develop in thin film interconnects mainly as a result of deposition conditions and multiple thermal loading cycles during the manufacturing flow. Understanding the relation between the distribution of residual stress and the interconnect microstructure is of key importance to manage the nucleation and growth of defects that can lead to failure under reliability testing and use conditions. Dislocation dynamics simulations are performed in nanocrystalline copper subjected to cyclic loading to quantify the distribution of residual stresses as a function of grain misorientation and grain size distribution. The outcomes of this work help to evaluate the effect of microstructure in thin films failure by identifying potential voiding sites. Furthermore, the simulations show how dislocation structures are influenced by texture and grain size distribution that affect the residual stress. For example, when dislocation loops reach the opposite grain boundary during loading, these dislocations remain locked during unloading.
Comparison of Measured Residual Stress in an Extra Thick Multi-pass Weld Using Neutron Diffraction Method and Inherent Strain Method

International Nuclear Information System (INIS)

Park, JeongUng; An, GyuBaek; Woo, Wan Chuck

2015-01-01

With the increase of large-scale containership, a large amount of high-strength steels with extra thick plates is being extensively used. The welding stress existing in the extra thick welded plates has a significant effect on the integrity of the component in terms of brittle fracture and fatigue behavior. It has been reported that welding residual stress distribution in an extra thick plate can affect the propagation path of the crack. Therefore, it is important to measure the distribution of welding residual stresses for the reliable design of the welded structures. So far various researches have been carried out for the determination of residual stresses on the surface of steels. In this paper, the total residual stresses in the 70 mm thick multipass FACW butt joint were measured by integrating initial stress into ISM. Concretely, two methods named as initial stress integrated ISM and initial inherent strain integrated ISM were employed to determine the total residual stresses. Furthermore, the distributions of residual stresses were compared with the results of the Neutron Diffraction Method(NDM). In order to measure the three dimensional residual stresses in the welded joint with initial stresses existing before welding, initial stress integrated ISM and initial inherent strain integrated ISM were developed. The residual stresses in 70 mm-thick butt joint by flux cored arc welding were carried out with a good accuracy using the two developed methods. The residual stresses in welded joint using both initial stress integrated ISM and initial inherent strain integrated ISM agreed well with the results measured by Neutron Diffraction Method. This suggests that the integrated ISM is a reliable method for residual stress measurement if initial stress existed
Investigation of Performance and Residual Stress Generation of AlSi10Mg Processed by Selective Laser Melting

Directory of Open Access Journals (Sweden)

Lianfeng Wang

2018-01-01

Full Text Available During the selective laser melting (SLM process, the scanned layers are subjected to rapid thermal cycles. By working on the mechanical properties, residual stress, and microstructure, the high-temperature gradients can have significant effect on the proper functioning and the structural integrity of built parts. This work presents a comprehensive study on the scanning path type and preheating temperature for AlSi10Mg alloy during SLM. According to the results, SLM AlSi10Mg parts fabricated in chessboard scanning strategy have higher mechanical properties or at least comparable to the parts fabricated in uniformity scanning strategy. In the SLM processing, the residual stress in different parts of the specimen varies with temperature gradient, and the residual stress at the edge of the specimen is obviously larger than that at the center. Under the chessboard scanning and preheating temperature 160°C, the residual stress in each direction of the specimens reaches the minimum. Under different forming processes, the morphology of the microstructure is obviously different. With the increase of preheating temperature, the molten pool in the side surface is obviously elongated and highly unevenly distributed. From the coupling relationship between the residual stress and microstructure, it can be found that the microstructure of top surface is affected by residual stresses σx and σy. But the side surface is mainly governed by residual stress σy; moreover, the greater the residual stress, the more obvious the grain tilt. In the XY and XZ surfaces, the scanning strategy has little influence on the tilt angle of the grain. But, the tilt angle and morphology of the microstructure are obviously affected by the preheating temperature. The results show that the residual stresses can effectively change the properties of the materials under the combined influence of scanning strategy and preheating temperature.
The residual stress evaluation for expansion process of steam generator tubes

International Nuclear Information System (INIS)

King, C.-S.; Lee, S.-C.; Shim, D.-N.

2004-01-01

The reliability of a nuclear power plant is affected by the reliability of steam generator tube and the reliability of steam generator tube is affected by stress corrosion cracking(SCC). Many steam generator tubes were experiencing stress corrosion cracking and stress corrosion cracking is affected material characteristics, corrosive environments and added stresses. The added stresses have the manufacturing stresses and operating stresses, the manufacturing stresses include the residual stresses generating in the tube manufacture and tube expanding procedure. We will investigate for influence which affected to residual stresses with tube plastic deformation method and measurement region. (author)
Measurement of residual stress in textured Al alloy by neutron diffraction method

International Nuclear Information System (INIS)

Okido, S.; Hayashi, M.; Tanaka, K.; Akiniwa, Y.; Minakawa, N.; Morii, Y.

1999-01-01

Residual stress generated in a shrunken aluminum alloy specimen, which was prepared for the round robin test conducted by VAMAS (Versailles Project on Advanced Materials and Standards) TWA-20 organized for the purpose of standardizing residual stress measurement methods, was evaluated by a neutron diffraction method. The main purpose of the round robin test was to assess the reproducibility of data obtained with the measurement facilities of the participants. The general standard of the Residual Stress Analyzer (RESA) constructed in the Japan Atomic Energy Research Institute was verified from the measured residual strains, which were equivalent to the values calculated by FEM and values measured by the research facilities in North America. Residual stress was calculated from residual strain in three perpendicular directions. The diffraction intensities were dependent on measurement directions since the prepared specimen possessed texture. Diffraction profiles in directions having a weak diffraction intensity caused an inaccurate evaluation of the residual stress. To solve this problem, a new method for evaluating residual stress with respect to diffraction plane dependency of the elastic constant was applied. The diffraction plane giving the highest intensity among 110, 200, and 220 diffraction was used to evaluate the residual strain in each of three directions. The residual strain obtained on the used diffraction plane was converted to the equivalent strain for the defined diffraction plane using the ratio of elastic constants of these two planes. The developed evaluation method achieved highly accurate measurement and remarkable efficiency in the measurement process. (author)
Residual stress evaluation by Barkhausen signals with a magnetic field sensor for high efficiency electrical motors

Science.gov (United States)

Tsuchida, Yuji; Enokizono, Masato

2018-04-01

The iron loss of industrial motors increases by residual stress during manufacturing processes. It is very important to make clear the distribution of the residual stress in the motor cores to reduce the iron loss in the motors. Barkhausen signals which occur on electrical steel sheets can be used for the evaluation of the residual stress because they are very sensitive to the material properties. Generally, a B-sensor is used to measure Barkhausen signals, however, we developed a new H-sensor to measure them and applied it into the stress evaluation. It is supposed that the Barkhausen signals by using a H-sensor can be much effective to the residual stress on the electrical steel sheets by referring our results regarding to the stress evaluations. We evaluated the tensile stress of the electrical steel sheets by measuring Barkhausen signals by using our developed H-sensor for high efficiency electrical motors.
Effects of residual stress on fatigue strength of small diameter welded pipe joint

International Nuclear Information System (INIS)

Yamashita, Tetsuo; Hattori, Takahiro; Nomoto, Toshiharu; Iida, Kunihiro; Sato, Masanobu

1996-01-01

A power plant consists of many welded components, therefore, it is essential in establishing the reliability of the power plant to maintain the reliability of all welded components. The fatigue failure caused by mechanical vibrations of small diameter welded joints, which is represented by socket welded joints, is one of the major causes of trouble for the welded parts of the power plant. Here, bending fatigue tests were conducted to investigate the fatigue strength of small diameter socket welded pipe joints. In the most cases of large diameter socket joints, a fatigue crack started from the root of the fillet weld though the stress amplitude at the root was smaller than that at the toe of fillet weld. Additionally, the fatigue strength was affected by the weld bead sequence. The residual stress was considered to be one of the important parameters governing fatigue strength, therefore, its effects were investigated. In several types of pipe joints, the local stress and residual stress distributions were calculated by finite element analysis. The residual stresses were compressive at the toe and tensile at the root of the socket welded joints. Based on these results, the effects of residual stresses on the fatigue strength are discussed for small diameter welded pipe joints in the present work
Residual stress evaluation and curvature behavior of aluminium 7050 peen forming processed; Avaliacao da tensao residual em aluminio 7050 conformado pelo processo peen forming

Energy Technology Data Exchange (ETDEWEB)

Oliveira, R.R. de; Lima, N.B., E-mail: rolivier@ipen.b, E-mail: nblima@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Braga, A.P.V.; Goncalves, M., E-mail: anapaola@ipt.b, E-mail: mgoncalves@ipt.b [Instituto de Pesquisas Tecnologicas (IPT), Sao Paulo, SP (Brazil)

2010-07-01

Shot peening is a superficial cold work process used to increase the fatigue life evaluated by residual stress measurements. The peen forming process is a variant of the shot peening process, where a curvature in the plate is obtained by the compression of the grains near to the surface. In this paper, the influence of the parameters such as: pressure of shot, ball shot size and thickness of aluminum 7050 samples with respect to residual stress profile and resulting arc height was studied. The evaluation of the residual stress profile was obtained by sin{sup 2} {Psi} method. (author)
Comparison of welding induced residual stresses austenitic and ferritic steel weld joints

International Nuclear Information System (INIS)

Rajkumar, K.V.; Arun Kumar, S.; Mahadevan, S.; Manojkumar, R.; Rao, B. Purna Chandra; Albert, Shaju K.; Murugan, S.

2015-01-01

X-ray diffraction (XRD) is a well established technique for measurement of residual stresses in components and is being widely used. In XRD technique, the distance between the crystallographic planes (d spacing) is measured from peak position (2è) at various ø angles, where ø is the angle between the normal to the sample and the bisector of the incident and diffracted beam. From the slope of sin2ø vs. d spacing plot, the residual stresses are arrived by assuming a plane stress model. Welding induced residual stresses is of high importance as it is a major cause of failure in components. Surface compressive stresses improve the fatigue strength, whereas tensile residual stresses tend to decrease the fatigue strength. The present study compares the residual stresses that develop in 3 mm thick SS 316 and P91 TIG weld joints using the XRD technique. This study is aimed at understanding the influence of shrinkage during cooling and the effect of phase transformation induced volume changes on residual stress development in these two steels. While the first effect is predominant in the SS 316 weld, both the effects are present in the P91 welds. Stress measurements on SS 316 and P91 were carried out using Cr Kâ (λ-2.0840 Å) and Cr Ká (λ-2.2896 Å) radiations respectively. Typical 'M' type stress profile was observed across the weld centre line in both the welds. The variation and similarities between the longitudinal stress profiles observed in these two weld joints would be discussed. (author)
Study by X-ray diffraction and mechanical analysis of the residual stress generation during thermal spraying

International Nuclear Information System (INIS)

Pina, J.; Dias, A.; Lebrun, J.L.

2003-01-01

Thermally sprayed coatings are formed by the deposition of molten or partially molten particles, propelled onto a substrate where they impact, spread and solidify rapidly. Residual stresses are expected within the sprayed deposit as a consequence of the release of thermal and kinetic energies. A wide range of materials and two spraying techniques are considered in this study, namely atmospheric plasma spraying (APS) and high-velocity oxygen fuel. Stresses were determined by the X-ray diffraction (XRD) method. The results were compared with those calculated by mechanical analysis of stress relief in coatings detached from the substrate. Comparison of the results for adherent and free-standing coatings shows that the residual stress state can be resolved in terms of the components suggested by models that propose two stages of stress generation: quenching stresses and secondary-cooling stresses. The in-depth distribution of residual stresses, through the coating thickness, is discussed in terms of the nature of the coating system
Microstructure and temperature dependence of intergranular strains on diffractometric macroscopic residual stress analysis

Energy Technology Data Exchange (ETDEWEB)

Wagner, J.N., E-mail: Julia.Wagner@kit.edu [KNMF, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Hofmann, M. [Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II), TU München, Lichtenbergstr. 1, 85747 Garching (Germany); Wimpory, R. [Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin Wannsee (Germany); Krempaszky, C. [Christian-Doppler-Labor für Werkstoffmechanik von Hochleistungslegierungen, TU München, Boltzmannstr. 15, 85747 Garching (Germany); Lehrstuhl für Werkstoffkunde und Werkstoffmechanik, TU München, Boltzmannstr. 15, 85747 Garching (Germany); Stockinger, M. [Böhler Schmiedetechnik GmbH and Co KG, Mariazeller Straße 25, 8605 Kapfenberg (Austria)

2014-11-17

Knowledge of the macroscopic residual stresses in components of complex high performance alloys is crucial when it comes to considering the safety and manufacturing aspects of components. Diffraction experiments are one of the key methods for studying residual stresses. However a component of the residual strain determined by diffraction experiments, known as microstrain or intergranular residual strain, occurs over the length scale of the grains and thus plays only a minor role for the life time of such components. For the reliable determination of macroscopic strains (with the minimum influence of these intergranular residual strains), the ISO standard recommends the use of particular Bragg reflections. Here we compare the build-up of intergranular strain of two different precipitation hardened IN 718 (INCONEL 718) samples, with identical chemical composition. Since intergranular strains are also affected by temperature, results from room temperature measurement are compared to results at T=550 °C. It turned out that microstructural parameters, such as grain size or type of precipitates, have a larger effect on the intergranular strain evolution than the influence of temperature at the measurement temperature of T=550 °C. The results also show that the choice of Bragg reflections for the diffractometric residual stress analysis is dependent not only on its chemical composition, but also on the microstructure of the sample. In addition diffraction elastic constants (DECs) for all measured Bragg reflections are given.
Residual stress in polyethylene pipes

Czech Academy of Sciences Publication Activity Database

Poduška, Jan; Hutař, Pavel; Kučera, J.; Frank, A.; Sadílek, J.; Pinter, G.; Náhlík, Luboš

2016-01-01

Roč. 54, SEP (2016), s. 288-295 ISSN 0142-9418 R&D Projects: GA MŠk LM2015069; GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : polyethylene pipe * residual stress * ring slitting method * lifetime estimation Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.464, year: 2016
Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

National Research Council Canada - National Science Library

Underwood, John

2000-01-01

...; overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid...

Analysis of the Residual Stresses in Helical Cylindrical Springs at High Temperature

Directory of Open Access Journals (Sweden)

H. Sun

2015-01-01

Full Text Available Creep is one of the basic properties of materials, its speed significantly depends on the temperature. Helical cylindrical springs are widely used in the elements of heating systems. This results in necessity of taking into account the effect of temperature on the stress-strain state of the spring. The object of research is a helical cylindrical spring used at high temperatures. Under this condition the spring state stability should be ensured.The paper studies relaxation of stress state and generation of residual stresses. Calculations are carried out in ABAQUS environment. The purpose of this work is to discuss the law of relaxation and residual stress in the spring.This paper describes the basic creep theories of helical cylindrical spring material. The calculation formulas of shear stress relaxation for a fixed compression ratio are obtained. Distribution and character of stress contour lines in the cross section of spring are presented. The stress relaxation – time relationships are discussed. The approximate formula for calculating relaxation shear stresses in the cross section of helical springs is obtained.The paper investigates creep ratio and law of residual stress variation in the cross-section of spring at 650℃. Computer simulation in ABAQUS environment was used. Research presents a finite element model of the spring creep in the cross-section.The paper conducts analysis of the stress changes for the creep under constant load. Under constant load stresses are quickly decreased in the around area of cross-section and are increased in the centre, i.e. the maximum and minimum stresses come close with time. Research work shows the possibility for using the approximate formula to calculate the relaxation shear stress in the cross section of spring and can provide a theoretical basis for predicting the service life of spring at high temperatures.In research relaxation processes of stress state are studied. Finite element model is cre
Neutron diffraction measurements of residual stresses in NPP construction materials

International Nuclear Information System (INIS)

Hinca, R.; Bokuchava, G.

2001-01-01

Neutron diffraction is one of the most powerful methods for condensed matter studies. This method is used for non-destructive determination of residual stresses in material. The fundamental aspects of neutron diffraction are discussed, together with a brief description of the experimental facility. The principal advantage of using neutrons rather than the more conventional X-rays is the fact that neutron can penetrate deeply (2-4 cm for steel and more than 10 cm for aluminium) into metals to determine internal parameters within the bulk of materials. We present results of measurements residual stresses in NPP construction material - austenitic stainless steel (Cr-18%, Ni-10%, Ti-1%) coated with high-nickel alloy. (authors)
Measurement of edge residual stresses in glass by the phase-shifting method

Science.gov (United States)

Ajovalasit, A.; Petrucci, G.; Scafidi, M.

2011-05-01

Control and measurement of residual stress in glass is of great importance in the industrial field. Since glass is a birefringent material, the residual stress analysis is based mainly on the photoelastic method. This paper considers two methods of automated analysis of membrane residual stress in glass sheets, based on the phase-shifting concept in monochromatic light. In particular these methods are the automated versions of goniometric compensation methods of Tardy and Sénarmont. The proposed methods can effectively replace manual methods of compensation (goniometric compensation of Tardy and Sénarmont, Babinet and Babinet-Soleil compensators) provided by current standards on the analysis of residual stresses in glasses.
Effects of material non-linearity on the residual stresses in a dendritic silicon crystal ribbon

Science.gov (United States)

Ray, Sujit K.; Utku, Senol

1990-01-01

Thermal stresses developed in a dendritic silicon crystal ribbon have been shown to cause plastic deformation and residual stresses in the ribbon. This paper presents an implementation of a numerical model proposed for thermoelastoplastic behavior of a material. The model has been used to study the effects of plasticity of silicon on the residual stresses. The material properties required to implement this model are all assumed, and the response of the material to the variations in these assumed parameters of the constitutive law and in the finite element mesh is investigated. The steady state growth process is observed to be periodic with nonzero residual stresses. Numerical difficulties are also encountered in the computer solution process, resulting in sharp jumps and large oscillations in the stress responses.
Significance of residual stress on fatigue properties of welded pipes

International Nuclear Information System (INIS)

Ohta, A.; Maeda, Y.; Kanao, M.

1984-01-01

The mean stress effect on the fatigue properties of two kinds of welded pipes was investigated in cantilever bending. The fatigue strength changed with the mean stress on fillet welded pipes, but did not change on butt welded pipes. The fatigue crack initiated from the toe of weld on the outer surface of fillet welded pipes and from the undercut on the inner surface of butt welded pipes. The measurement of the fatigue crack propagation rate and the residual stress distribution through the thickness of pipe revealed that the difference in the fatigue properties between fillet and butt welded pipes arose from the weld-induced residual stress, tension on the inner surface and compression on the outer surface. It is suggested that the production of compressive residual stress along the inner surface would be an effective means for improving the fatigue strength of butt welded pipes. (author)
Residual stress in sprayed Ni+5%Al coatings determined by neutron diffraction

CERN Document Server

Matejicek, J; Gnaeupel-Herold, T; Prask, H J

2002-01-01

Coatings of nickel-based alloys are used in numerous high-performance applications. Their properties and lifetimes are influenced by factors such as residual stress. Neutron diffraction is a powerful tool for nondestructive residual stress determination. In this study, through-thickness residual stress profiles in Ni+5%Al coatings on steel substrates were determined. Two examples of significantly different spraying techniques - plasma spraying and cold spraying - are highlighted. Different stress-generation mechanisms are discussed with respect to process parameters and material properties. (orig.)
The influence of residual stresses on small through-clad cracks in pressure vessels

International Nuclear Information System (INIS)

deLorenzi, H.G.; Schumacher, B.I.

1984-01-01

The influence of cladding residual stresses on the crack driving force for shallow cracks in the wall of a nuclear pressure vessel is investigated. Thermo-elastic-plastic analyses were carried out on long axial through-clad and sub-clad flaws on the inside of the vessel. The depth of the flaws were one and three times the cladding thickness, respectively. An analysis of a semielliptical axial through-clad flaw was also performed. It was assumed that the residual stresses arise due to the difference in the thermal expansion between the cladding and the base material during the cool down from stress relieving temperature to room temperature and due to the subsequent proof test before the vessel is put into service. The variation of the crack tip opening displacement during these loadings and during a subsequent thermal shock on the inside wall is described. The analyses for the long axial flaws suggest that the crack driving force is smaller for this type of flaw if the residual stresses in the cladding are taken into account than if one assumes that the cladding has no residual stresses. However, the analysis of the semielliptical flaw shows significantly different results. Here the crack driving force is higher than when the residual stresses are not taken into account and is maximum in the cladding at or near the clad/base material interface. This suggests that the crack would propagate along the clad/base material interface before it would penetrate deeper into the wall. The elastic-plastic behavior found in the analyses show that the cladding and the residual stresses in the cladding should be taken into acocunt when evaluating the severity of shallow surface cracks on the inside of a nuclear pressure vessel
A Study on the Residual Stress Improvement of PWSCC(Primary Water Stress Corrosion Cracking) in DMW(Dissimilar Metal Weld)

International Nuclear Information System (INIS)

Kang, Sung Sik; Kim, Seok Hun; Lee, Seung Gun; Park, Heung Bae

2010-01-01

Since 2000s, most of the cracks are found in welds, especially in (DMW) dissimilar metal welds such as pressurizer safety relief nozzle, reactor head penetration, reactor bottom mounted instrumentation (BMI), and reactor nozzles. Even the cracks are revealed as a primary water stress corrosion cracking (PWSCC), it is difficult to find the cracks by current non destructive examination. The PWSCC is occurred by three incident factors, such as susceptible material, environmental corrosive condition, and welding residual stress. If one of the three factors can be erased or decreased, the PWSCC could be prevented. In this study, we performed residual stress analysis for DMW and several residual stress improvement methods. As the preventive methods of PWSCC, we used laser peening(IP) method, inlay weld(IW) method, and induction heating stress improvement(IHSI) method. The effect of residual stress improvement for preventive methods was compared and discussed by finite element modeling and residual stress of repaired DMW
Estimation of residual stress in welding of dissimilar metals at nuclear power plants using cascaded support vetor regression

Energy Technology Data Exchange (ETDEWEB)

Koo, Young Do; Yoo, Kwae Hwan; Na, Man Gyun [Dept. of Nuclear Engineering, Chosun University, Gwangju (Korea, Republic of)

2017-06-15

Residual stress is a critical element in determining the integrity of parts and the lifetime of welded structures. It is necessary to estimate the residual stress of a welding zone because residual stress is a major reason for the generation of primary water stress corrosion cracking in nuclear power plants. That is, it is necessary to estimate the distribution of the residual stress in welding of dissimilar metals under manifold welding conditions. In this study, a cascaded support vector regression (CSVR) model was presented to estimate the residual stress of a welding zone. The CSVR model was serially and consecutively structured in terms of SVR modules. Using numerical data obtained from finite element analysis by a subtractive clustering method, learning data that explained the characteristic behavior of the residual stress of a welding zone were selected to optimize the proposed model. The results suggest that the CSVR model yielded a better estimation performance when compared with a classic SVR model.
Residual stress measurement method in MEMS microbeams using frequency shift data

International Nuclear Information System (INIS)

Somà, Aurelio; Ballestra, Alberto

2009-01-01

The dynamical behaviour of a set of gold microbeams affected by residual stress has been studied. Experimental frequency shift curves were obtained by increasing the dc voltage applied to the specimens. Comparison with different analytical and numerical models has been carried out in order to identify both analytical and finite element models in the presence of residual stress. Residual strain and stress, due to the fabrication process, have been widely reported in the literature in both out-of-plane microcantilevers and clamped–clamped microbeams by using mainly the value of pull-in voltage and static deflection data. In the case of a microcantilever, an accurate modelling includes the effect of the initial curvature due to microfabrication. In double-clamped microbeams, a pre-load applied by tensile stress is considered. A good correspondence is pointed out between measurements and numerical models so that the residual stress effect can be evaluated for different geometrical configurations
Residual stresses estimation in tubes after rapid heating of surface

International Nuclear Information System (INIS)

Serikov, S.V.

1992-01-01

Results are presented on estimation of residual stresses in tubes of steel types ShKh15, EhP836 and 12KIMF after heating by burning pyrotechnic substance inside tubes. External tube surface was heated up to 400-450 deg C under such treatment. Axial stresses distribution over tube wall thickness was determined for initial state, after routine heat treatment and after heating with the use of fireworks. Inner surface heating was shown to essentially decrease axial stresses in tubes
The effects of location, thermal stress, and residual stress on corner cracks in nozzles with cladding

International Nuclear Information System (INIS)

Besuner, P.M.; Cohen, L.M.; McLean, J.L.

1977-01-01

The stress intensity factors (Ksub(I)) for corner cracks in a boiling water reactor feedwater nozzle with stainless steel cladding are obtained for loading by internal pressure, and a fluid quench in the nozzle. Conditions with and without residual stress in the component are considered. The residual stress is simulated by means of a reference temperature change. The stress distribution for the uncracked structure is obtained from a three-dimensional finite element model. A three-dimensional influence function (IF) method, in conjunction with the boundary-integral equation method for structural analysis is employed to compute Ksub(I) values from the uncracked structure's stress distribution. It is concluded that the effects on Ksub(I) of location, thermal stresses, and residual stresses are significant and generally too complex to evaluate without advanced numerical procedures. The ulilized combination of finite element analysis of the uncracked structure and three-dimensional influence function analysis of the cracked structure is demonstrated and endorsed. (Auth.)
Numerical analysis of residual stresses reconstruction for axisymmetric glass components

Science.gov (United States)

Tao, Bo; Xu, Shuang; Yao, Honghui

2018-01-01

A non-destructive measurement method for 3D stress state in a glass cylinder using photoelasticity has been analyzed by simulation in this research. Based on simulated stresses in a glass cylinder, intensity of the cylinder in a circular polariscope can be calculated by Jones calculus. Therefore, the isoclinic angle and optical retardation can be obtained by six steps phase shifting technique. Through the isoclinic angle and optical retardation, the magnitude and distribution of residual stresses inside the glass cylinder in cylindrical coordinate system can be reconstructed. Comparing the reconstructed stresses with numerical simulated stresses, the results verify this non-destructive method can be used to reconstruct the 3D stresses. However, there are some mismatches in axial stress, radial stress and circumferential stress.
Influence of residual stress on the adhesion and surface morphology of PECVD-coated polypropylene

Science.gov (United States)

Jaritz, Montgomery; Hopmann, Christian; Behm, Henrik; Kirchheim, Dennis; Wilski, Stefan; Grochla, Dario; Banko, Lars; Ludwig, Alfred; Böke, Marc; Winter, Jörg; Bahre, Hendrik; Dahlmann, Rainer

2017-11-01

The properties of plasma-enhanced chemical vapour deposition (PECVD) coatings on polymer materials depend to some extent on the surface and material properties of the substrate. Here, isotactic polypropylene (PP) substrates are coated with silicon oxide (SiO x ) films. Plasmas for the deposition of SiO x are energetic and oxidative due to the high amount of oxygen in the gas mixture. Residual stress measurements using single Si cantilever stress sensors showed that these coatings contain high compressive stress. To investigate the influence of the plasma and the coatings, residual stress, silicon organic (SiOCH) coatings with different thicknesses between the PP and the SiO x coating are used as a means to protect the substrate from the oxidative SiO x coating process. Pull-off tests are performed to analyse differences in the adhesion of these coating systems. It could be shown that the adhesion of the PECVD coatings on PP depends on the coatings’ residual stress. In a PP/SiOCH/SiO x -multilayer system the residual stress can be significantly reduced by increasing the thickness of the SiOCH coating, resulting in enhanced adhesion.
Investigation of the Residual Stress State in an Epoxy Based Specimen

DEFF Research Database (Denmark)

Baran, Ismet; Jakobsen, Johnny; Andreasen, Jens Henrik

2015-01-01

Abstract. Process induced residual stresses may play an important role under service loading conditions for fiber reinforced composite. They may initiate premature cracks and alter the internal stress level. Therefore, the developed numerical models have to be validated with the experimental...... observations. In the present work, the formation of the residual stresses/strains are captured from experimental measurements and numerical models. An epoxy/steel based sample configuration is considered which creates an in-plane biaxial stress state during curing of the resin. A hole drilling process...... material models, i.e. cure kinetics, elastic modulus, CTE, chemical shrinkage, etc. together with the drilling process using the finite element method. The measured and predicted in-plane residual strain states are compared for the epoxy/metal biaxial stress specimen....
Numerical investigation on residual stress distribution and evolution during multipass narrow gap welding of thick-walled stainless steel pipes

International Nuclear Information System (INIS)

Liu, C.; Zhang, J.X.; Xue, C.B.

2011-01-01

Research highlights: → We performed pass-by-pass simulation of stresses for welding of thick-walled pipes. → The distributions and evolution of the residual stresses are demonstrated. → After the groove is filled to a height, the through-wall stress is almost unchanged. - Abstracts: The detailed pass-by-pass finite element (FE) simulation is presented to investigate the residual stresses in narrow gap multipass welding of pipes with a wall thickness of 70 mm and 73 weld passes. The simulated residual stress on the outer surface is validated with the experimental one. The distribution and evolution of the through-wall residual stresses are demonstrated. The investigated results show that the residual stresses on the outer and inner surfaces are tensile in the weld zone and its vicinity. The through-wall axial residual stresses at the weld center line and the HAZ line demonstrate a distribution of bending type. The through-wall hoop residual stress within the weld is mostly tensile. After the groove is filled to a certain height, the peak tensile stresses and the stress distribution patterns for both axial and hoop stresses remain almost unchanged.
Effects of location, thermal stress and residual stress on corner cracks in nozzles with cladding

International Nuclear Information System (INIS)

McLean, J.L.; Cohen, L.M.; Besuner, P.M.

1979-01-01

The stress intensity factors (K 1 ) for corner cracks in a boiling water reactor feedwater nozzle with stainless steel cladding are obtained for loading by internal pressure and a fluid quench in the nozzle. Conditions both with and without residual stress in the component are considered. The residual stress is simulated by means of a reference temperature change. The stress distribution for the uncracked structure is obtained from a three-dimensional finite element model. A three-dimensional influence function (IF) method, in conjunction with the boundary-integral equation method for structural analysis, is employed to compute K 1 values from the uncracked stress distribution. For each type of loading K 1 values are given for cracks at 15 nozzle locations and for 6 crack depths. Reasonable agreement is noted between calculated and previously published pressure-induced K 1 values. Comparisons are made to determine the effect on K 1 of crack location, thermal stress and residual stress, as compared with pressure stress. For the thermal transient it is shown that K 1 for small crack depths is maximised early in the transient, while K 1 for large cracks is maximised later under steady state conditions. Computation should, therefore, be made for several transient time points and the maximum K 1 for a given crack depth should be used for design analysis. It is concluded that the effects on K 1 of location, thermal stresses and residual stresses are significant and generally too complex to evaluate without advanced numerical procedures. The utilised combination of finite element analysis of the uncracked structure and three-dimensional influence function analysis of the cracked structure is demonstrated and endorsed. (author)
Residual stress improvement mechanism on metal material by underwater laser irradiation

International Nuclear Information System (INIS)

Sano, Yuji; Yoda, Masaki; Mukai, Naruhiko; Obata, Minoru; Kanno, Masanori

2000-01-01

Residual stress improvement technology for component surface by underwater pulsed laser irradiation has been developed as a method of preventing stress corrosion cracking (SCC) of core components in nuclear reactors. In order to optimize the laser irradiation conditions based on a complete understanding of the mechanism, the propagation of a shock wave induced by the impulse of laser irradiation and the dynamic response of the irradiated material were analyzed through time-dependent elasto-plastic calculations with a finite element program. The calculated results are compared with the measured results obtained by experiments in which laser pulses with an energy of 200 mJ are focused to a diameter of 0.8 mm on a water-immersed test piece of 20% cold-worked Type 304 austenitic stainless steel to simulate neutron irradiation hardening. A residual compressive stress, which is nearly equivalent to the yield stress of the processed material, remains on the material surface after passage of the shock wave with enough amplitude to induce a permanent strain. Multiple irradiation of laser pulses extends the stress-improved depth to about 1 mm, which would be the limit corresponding to the three-dimensional dispersion effect of the shock wave. (author)
Comparison of neutron and synchrotron diffraction measurements of residual stress in bead-on-plate weldments

International Nuclear Information System (INIS)

Paradowska, A.M.; Price, J.W.; Finlayson, T.R.; Lienert, U.; Ibrahim, R.

2010-01-01

This paper explores the use of neutron and synchrotron diffractions for the evaluation of residual stresses in welded components. It has been shown that it is possible to achieve very good agreement between the two independent diffraction techniques. This study shows the significance of the weld start and end sites on the residual strain/stress distribution. Quantitative evaluation of the residual stress development process for multibead weldments has been presented. Some measurements were also taken before and after postweld stress relieving to establish the reduction and redistribution of the residual stress. The detailed measurements of residual stress around the weld achieved in this work significantly improve the knowledge and understanding of residual stress in welded components.
The role and effect of residual stress on pore generation during anodization of aluminium thin films

International Nuclear Information System (INIS)

Liao, M.W.; Chung, C.K.

2013-01-01

Highlights: •Al films of varying residual stress were prepared by sputtering. •Variation of the residual stress in the Al films influences pore growth during anodization. •The change in average pore size with residual stress is fairly small. •Interaction of residual stress with oxide growth stress leads to change in structure. •Residual tensile stress increases the pore density of porous alumina. -- Abstract: The role and effect of residual stress on pore generation of anodized aluminium oxide (AAO) have been investigated into anodizing the various-residual-stresses aluminium films. The plane stresses were characterised by X-ray diffraction with sin 2 ψ method. The pore density roughly linearly increased with residual stress from 64.6 (−132.5 MPa) to 90.5 pores/μm 2 (135.9 MPa). However, the average pore size around 40 nm was not changed significantly except for the rougher film. The tensile residual stress lessened the compressive oxide growth stress to reduce AAO plastic deformation for higher pore density. The findings provide new foundations for realizing AAO films on silicon

Remarks on residual stress measurement by hole-drilling and electronic speckle pattern interferometry.

Science.gov (United States)

Barile, Claudia; Casavola, Caterina; Pappalettera, Giovanni; Pappalettere, Carmine

2014-01-01

Hole drilling is the most widespread method for measuring residual stress. It is based on the principle that drilling a hole in the material causes a local stress relaxation; the initial residual stress can be calculated by measuring strain in correspondence with each drill depth. Recently optical techniques were introduced to measure strain; in this case, the accuracy of the final results depends, among other factors, on the proper choice of the area of analysis. Deformations are in fact analyzed within an annulus determined by two parameters: the internal and the external radius. In this paper, the influence of the choice of the area of analysis was analysed. A known stress field was introduced on a Ti grade 5 sample and then the stress was measured in correspondence with different values of the internal and the external radius of analysis; results were finally compared with the expected theoretical value.
Residual stress measurement of EB-welded plates with contour method. Part 2: FEM analysis of contour profiles

International Nuclear Information System (INIS)

Romppanen, A.-J.; Immonen, E.

2013-12-01

The residual stresses formed as a result of Electronic Beam welding (EB-welding) in copper are investigated by Posiva. In the present study, residual stresses of EB-welded copper plates were studied with contour method. In the method eleven copper plates (X436 - X440 and X453 - X458) were cut in half with wire electric discharge machining (EDM) after which the deformation due to stress relaxation was measured with coordinate measurement system. The measured data was then used as boundary displacement data for the FEM analyses, in which the corresponding residual stresses were calculated. Before giving the corresponding displacement boundary conditions to the FE models, the deformation data was processed and smoothed appropriately. The residual stress levels of the copper plates were found to be around 40 - 55 MPa at maximum. This corresponds to other reported residual stress measurements and current state of knowledge with this material in Posiva. (orig.)
The influence of alloy composition on residual stresses in heat treated aluminium alloys

Energy Technology Data Exchange (ETDEWEB)

Robinson, J.S., E-mail: jeremy.robinson@ul.ie [Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick (Ireland); Redington, W. [Materials and Surface Science Institute, University of Limerick (Ireland)

2015-07-15

The as quenched properties of eight different heat treatable aluminium alloys are related to residual stress magnitudes with the objective being to establish if there is a relationship between the residual stress and the as quenched alloy hardness and strength. Near surface residual stresses were assessed with X-ray diffraction using both the established sin{sup 2}ψ method and the more recent cos α technique. Through thickness residual stresses were also characterised using neutron diffraction. The alloys were chosen to encompass a wide range of strengths. The low to medium strength alloys were 6060 and 6082, medium to high strength 2618A, 2014A, 7075, 7010 and two variants of 7449, while the very high strength alloy was the powder metallurgy alloy N707. To assess the as quenched strength, dynamic hardness and tensile properties were determined from samples tested immediately after quenching to minimise the influence of precipitation hardening by natural aging. In addition, hot hardness measurements were made in situ on samples cooled to simulate quench paths. Within the experimental constraints of the investigation, the distribution of residual stress through the thickness was found to follow the same pattern for all the alloys investigated, varying from tensile in the interior to surface compression. The influence of alloy strength was manifested as a change in the observed residual stress magnitudes, and surface residual stresses were found to vary linearly with as quenched hardness and strength. - Highlights: • As quenched aluminium alloys contain high magnitude residual stresses. • Surface is compressive balance by a tensile core. • As quenched surface residual stress is linear function of alloy strength. • In situ hot hardness demonstrates rapid change in intrinsic hardness during rapid cooling.
The significance of residual stresses in relation to the integrity of LWR pressure vessels

International Nuclear Information System (INIS)

Lidbury, D.P.G.

1984-01-01

The level and distribution of residual stresses in heavy section weldments and the factors affecting their relaxation with post-weld heat treatment (PWHT) are discussed; residual stresses are also considered in relation to the deposition of austenitic strip cladding and repair welding. A brief survey is made of currently available methods of measuring surface and sub-surface residual stresses in heavy section weldments; the effects of compressive residual stresses on the detection and sizing of planar defects are similarly considered. Available fracture mechanics methodologies with the capability of evaluation defect significance in the presence of residual and other secondary stresses are reviewed in some detail. On-going experimental investigations of the effects of residual stresses on structural integrity are also described. Following a general discussion, the desirability of internationally agreed Codes and Methods for assessing defects in the presence of residual and other self-limiting stresses is pointed out. It is argued that before such agreement could be achieved, however, further work is necessary, and a number of recommendations are given. (author)
Principles of the measurement of residual stress by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Webster, G A; Ezeilo, A N [Imperial Coll. of Science and Technology, London (United Kingdom). Dept. of Mechanical Engineering

1996-11-01

The presence of residual stresses in engineering components can significantly affect their load carrying capacity and resistance to fracture. In order to quantify their effect it is necessary to know their magnitude and distribution. Neutron diffraction is the most suitable method of obtaining these stresses non-destructively in the interior of components. In this paper the principles of the technique are described. A monochromatic beam of neutrons, or time of flight measurements, can be employed. In each case, components of strain are determined directly from changes in the lattice spacings between crystals. Residual stresses can then be calculated from these strains. The experimental procedures for making the measurements are described and precautions for achieving reliable results discussed. These include choice of crystal planes on which to make measurements, extent of masking needed to identify a suitable sampling volume, type of detector and alignment procedure. Methods of achieving a stress free reference are also considered. A selection of practical examples is included to demonstrate the success of the technique. (author) 14 figs., 1 tab., 18 refs.
Principles of the measurement of residual stress by neutron diffraction

International Nuclear Information System (INIS)

Webster, G.A.; Ezeilo, A.N.

1996-01-01

The presence of residual stresses in engineering components can significantly affect their load carrying capacity and resistance to fracture. In order to quantify their effect it is necessary to know their magnitude and distribution. Neutron diffraction is the most suitable method of obtaining these stresses non-destructively in the interior of components. In this paper the principles of the technique are described. A monochromatic beam of neutrons, or time of flight measurements, can be employed. In each case, components of strain are determined directly from changes in the lattice spacings between crystals. Residual stresses can then be calculated from these strains. The experimental procedures for making the measurements are described and precautions for achieving reliable results discussed. These include choice of crystal planes on which to make measurements, extent of masking needed to identify a suitable sampling volume, type of detector and alignment procedure. Methods of achieving a stress free reference are also considered. A selection of practical examples is included to demonstrate the success of the technique. (author) 14 figs., 1 tab., 18 refs
Process induced residual stresses and distortions in pultrusion

DEFF Research Database (Denmark)

Baran, Ismet; Tutum, Cem Celal; Nielsen, Michael Wenani

2013-01-01

In the present study, a coupled 3D transient Eulerian thermo-chemical analysis together with a 2D plane strain Lagrangian mechanical analysis of the pultrusion process, which has not been considered until now, is carried out. The development of the process induced residual stresses and strains...... together with the distortions are predicted during the pultrusion in which the cure hardening instantaneous linear elastic (CHILE) approach is implemented. At the end of the process, tension stresses prevail for the inner region of the composite since the curing rate is higher here as compared to the outer...... regions where compression stresses are obtained. The separation between the heating die and the part due to shrinkage is also investigated using a mechanical contact formulation at the die-part interface. The proposed approach is found to be efficient and fast for the calculation of the residual stresses...
Simulation of stresses, residual stresses, and distortion in stepped cylinders of AISI 4140 due to martensitical hardening by immersion cooling

Energy Technology Data Exchange (ETDEWEB)

Ehlers, M.; Mueller, H.; Loehe, D. [Karlsruhe Univ. (Germany). Inst. for Materials Science and Engineering I

1999-09-01

Heat treatment improves mechanical properties of steel parts, but also causes residual stresses and distortion. Stresses and deformation occurring during heat treatment can not be measured in-situ with appropriate temporal and spatial resolution. In order to evaluate the processes occurring in the workpiece during quenching as well as the residual stresses and distortions, numerical methods have to be used. Heat conduction, phase transformations, and mechanical behaviour of the material as well as the couplings between the processes such as transformation plasticity have to be modeled for the simulation of steel hardening. Temperature and phase dependent properties (including TTT-data) have to incorporated into calculations. One of the major factors determining the evolution of stress and deformation is the heat-transfer coefficient between component and quenching medium. For vapourizing liquids, heat transfer depends on temperature and location. But heat transfer is not only influenced by the quenchant but also by part geometry and size. Stepped cylinders of AISI 4140 steel were quenched in water and oil. Both experimental measurements and numerical calculations were carried out. The variation of dive-in direction strongly influences the rewetting of the specimen surface and therefore the cooling behaviour, stress and deformation evolution, and resultant residual stresses and distortion. Excellent agreement is obtained between calculated and experimental results. (orig.)
Neutron and ultrasonic determination of residual stress in an aluminum ring-plug

International Nuclear Information System (INIS)

Prask, H.J.; Gnaeupel-Herold, T.; Clark, A.V.; Hehman, C.S.; Nguyen, T.N.

2000-01-01

Stress is a principal cause of material failure. This has been a well-recognized problem for decades, yet--in general--neutron diffraction remains the only way to measure sub-surface residual stresses without destroying the component. A field-portable ultrasonic strain-meter is being developed at NIST (Boulder) to determine residual stresses in engineering specimens, nondestructively. To test this and other techniques an array of stress-measurement standards are being prepared. These will be characterized by neutron diffraction and then used to evaluate, quantitatively, the potential of new methods. The first standard specimen produced for this purpose is a large shrink-fit ring-plug of 2024 aluminum (305 mm OD, 25.4 mm thick, 101.6 mm diameter plug). Because of large grain size, a sample-rotation averaging technique was developed to make reliable neutron measurements possible. A comparison of the neutron diffraction and ultrasonic results for this specimen will be presented, along with strain gauge results
Effects of stop–start features on residual stresses in a multipass austenitic stainless steel weld

International Nuclear Information System (INIS)

Turski, M.; Francis, J.A.; Hurrell, P.R.; Bate, S.K.; Hiller, S.; Withers, P.J.

2012-01-01

In this article we describe experiments that characterise and quantify the localised perturbations in residual stress associated with both ramped and abrupt stop–start features in a multipass weld. Residual stress distributions in AISI Grade 304L/308L stainless steel groove-welded specimens, containing weld interruptions that were introduced in a controlled manner, have been characterised using both neutron diffraction and the incremental deep hole drilling method. The extent to which the localised stresses associated with the interruptions were annealed by overlayed passes was also assessed. The results suggest that, regardless of the type of interruption, there can be significant localised increases in residual stress if the stop–start feature is left exposed. If further weld passes are deposited, then the localised increases in stress are likely to persist if the interruption was abrupt, whereas for a ramped interruption they may be dissipated. - Highlights: ► In this study the residual stress-field surrounding weld interruptions was measured. ► Localised stresses were found to increase at weld interruptions. ► Both ramped and abrupt weld interruptions were investigated. ► After subsequent weld passes, localised stresses persisted for abrupt interruptions. ► After subsequent weld passes, localised stresses dissipated for ramped interruptions.
The effects of machine parameters on residual stress determined using micro-Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sparks, R.G.; Enloe, W.S.; Paesler, M.A.

1988-12-01

The effects of machine parameters on residual stresses in single point diamond turned silicon and germanium have been investigated using micro-Raman spectroscopy. Residual stresses were sampled across ductile feed cuts in < 100 > silicon and germanium which were single point diamond turned using a variety of feed rates, rake angles and clearance angles. High spatial resolution micro-Raman spectra (1{mu}m spot) were obtained in regions of ductile cutting where no visible surface damage was present. The use of both 514-5nm and 488.0nm excitation wavelengths, by virtue of their differing characteristic penetration depths in the materials, allowed determinations of stress profiles as a function of depth into the sample. Previous discussions have demonstrated that such Raman spectra will exhibit asymmetrically broadened peaks which are characteristic of the superposition of a continuum of Raman scatterers from the various depths probed. Depth profiles of residual stress were obtained using computer deconvolution of the resulting asymmetrically broadened raman spectra.
A novel cryogenic treatment for reduction of residual stresses in 2024 aluminum alloy

Energy Technology Data Exchange (ETDEWEB)

Araghchi, M., E-mail: M.Araghchi@ma.iut.ac.ir [Department of Materials Engineering, Malek Ashtar University of Technology, Isfahan (Iran, Islamic Republic of); Mansouri, H.; Vafaei, R. [Department of Materials Engineering, Malek Ashtar University of Technology, Isfahan (Iran, Islamic Republic of); Guo, Yina [Bernal Institute, University of Limerick, Limerick (Ireland)

2017-03-24

Residual stresses induced during quenching of aluminum alloys cause distortion and have a negative effect on their properties. The purpose of this study is to reduce the residual stresses and improve mechanical properties by using a novel cryogenic treatment. Water quenched samples were cooled down by immersion in liquid nitrogen at −196 °C, following by rapid heating in hot oil at 180 °C and finally they were artificially aged. Residual stresses was measured by the hole drilling strain gauge method. The mechanical properties and microstructure of a heat treated samples were investigated by means of hardness measurements, tensile tests and transmission electron microscopy. The results showed that this treatment can relieve up to 71% of the residual stresses compared to 29% related to the traditional cryogenic treatment that used boiling water as the reheating medium. In addition, there is a considerable increase of about 75 MPa in the ultimate tensile strength in comparison to the T6 heat-treated alloy. TEM observations revealed that the S′ precipitates were fine and uniformly distributed in the microstructure due to deformation during reheating in hot oil.
Residual Stress Induced Mechanical Property Enhancement in Steel Encapsulated Light Metal Matrix Composites

Science.gov (United States)

Fudger, Sean James

Macro hybridized systems consisting of steel encapsulated light metal matrix composites (MMCs) were produced with the goal of creating a low cost/light weight composite system with enhanced mechanical properties. MMCs are frequently incorporated into advanced material systems due to their tailorable material properties. However, they often have insufficient ductility for many structural applications. The macro hybridized systems take advantage of the high strength, modulus, and damage tolerance of steels and high specific stiffness and low density of MMCs while mitigating the high density of steels and the poor ductility of MMCs. Furthermore, a coefficient of thermal expansion (CTE) mismatch induced residual compressive stress method is utilized as a means of improving the ductility of the MMCs and overall efficiency of the macro hybridized systems. Systems consisting of an A36, 304 stainless steel, or NitronicRTM 50 stainless steel shell filled with an Al-SiC, Al-Al2O3, or Mg-B4C MMC are evaluated in this work. Upon cooling from processing temperatures, residual strains are generated due to a CTE mismatch between each of the phases. The resulting systems offer higher specific properties and a more structurally efficient system can be attained. Mechanical testing was performed and improvements in yield stress, ultimate tensile stress, and ductility were observed. However, the combination of these dissimilar materials often results in the formation of intermetallic compounds. In certain loading situations, these typically brittle intermetallic layers can result in degraded performance. X-ray Diffraction (XRD), X-ray Energy Dispersive Spectroscopy (EDS), and Electron Backscatter Diffraction (EBSD) are utilized to characterize the intermetallic layer formation at the interface between the steel and MMC. As the residual stress condition in each phase has a large impact on the mechanical property improvement, accurate quantification of these strains/stresses is
Effects of LSP on micro-structures and residual stresses in a 4 mm CLAM steel weld joints

Energy Technology Data Exchange (ETDEWEB)

Chen, Xizhang, E-mail: chenxizhang@wzu.edu.cn [School of Mechanical and Electrical Engineering, Wenzhou University., Wenzhou 325035 (China); School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China); Fang, Yuanyuan [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China); Zhang, Shuyan; Kelleher, Joe F. [ISIS, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Zhou, Jianzhong [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China)

2015-05-15

The effects of laser shock processing (LSP) on the distribution of residual stress and micro-structure of China Low Activation Martensitic (CLAM) steel weldment were investigated via neutron diffraction and optical microscope (OM). A pair of 4 mm CLAM steel plates joined by GTA welding. Special attention is paid to the generation of high level compressive residual stresses introduced by LSP. Residual stress in longitudinal, normal and transversal direction at weldment surface and longitudinal stress through thickness are evaluated via neutron diffraction. Compressive residual stress after LSP occurred at more than 90% areas within the weld joint, it is almost double the areas of compressive stress compare to weldment surface before LSP. The maximum compressive normal residual stress becomes to −183 MPa after LSP from −63 MPa before LSP. The Modification of surface micro-structures including weld zone (WZ), heat affected zone (HAZ) and base metal (BM) are also discussed. Results to date demonstrate that laser shock processing has been a great potential method for the improvement of mechanical performance of components.
Measurement of residual stresses in deposited films of SOFC component materials

Energy Technology Data Exchange (ETDEWEB)

Kato, T.; Momma, A.; Nagata, S.; Kasuga, Y. [Electrotechnical Lab., Ibaraki (Japan)

1996-12-31

The stress induced in Solid oxide fuel cells (SOFC)s has important influence on the lifetime of SOFC. But the data on stress in SOFC and mechanical properties of SOW component materials have not been accumulated enough to manufacture SOFC. Especially, the data of La{sub 1-x}Sr{sub x}MnO{sub 3} cathode and La{sub 1-x}Sr{sub x}CrO{sub 3} interconnection have been extremely limited. We have estimated numerically the dependences of residual stress in SOFC on the material properties, the cell structure and the fabrication temperatures of the components, but these unknown factors have caused obstruction to simulate the accurate behavior of residual stress. Therefore, the residual stresses in deposited La{sub 1-x}Sr{sub x}MnO{sub 3} and La{sub 1-x}Sr{sub x}CrO{sub 3} films are researched by the observation of the bending behavior of the substrate strips. The films of SOFC component materials were prepared by the RF sputtering method, because: (1) It can fabricate dense films of poor sinterable material such as La{sub 1-x}Sr{sub x}CrO{sub 3} compared with sintering or plasma spray method. (2) For the complicated material such as perovskite materials, the difference between the composition of a film and that of a target material is generally small. (3) It can fabricate a thick ceramics film by improving of the deposition rate. For example, Al{sub 2}O{sub 3} thick films of 50{mu}m can be fabricated with the deposition rate of approximately 5{mu}m/h industrially. In this paper, the dependence of residual stress on the deposition conditions is defined and mechanical properties of these materials are estimated from the results of the experiments.
Residual Stresses in DC cast Aluminum Billet: Neutron Diffraction Measurements and Thermomechanical Modeling

International Nuclear Information System (INIS)

Drezet, J.-M.; Evans, A.; Pirling, T.

2011-01-01

Thermally-induced residual stresses, generated during the industrial Direct Chill casting process of aluminum alloys, can cause both significant safety concerns as well as the formation of defects during down-stream processing. Although these thermally induced strains can be partially relieved by permanent deformation, cracks will be generated either during solidification (hot tears) or post-solidification cooling (cold cracks) when stresses exceed the deformation limit of the alloy. Furthermore, the thermally induced strains result in the presence of large internal stresses within the billet before further processing steps. Although numerical models have been previously developed to compute these residual stresses, most of the computations have been validated only against measured surface distortions. In the present work, the variation in residual elastic strains and stresses in the steady state regime of casting has been measured as a function of radial position using neutron diffraction in an AA6063 grain-refined cylindrical billet. These measurements have been carried out on the same billet section at Poldi at PSI-Villigen and at Salsa at ILL-Grenoble and compare favorably. The results are used to validate a thermo-mechanical finite element casting model and to assess the level of stored elastic energy within the billet.
Residual stresses in non-symmetrical carbon-epoxy laminates

NARCIS (Netherlands)

Wijskamp, Sebastiaan; Akkerman, Remko; Lamers, E.A.D.; Martin, M.J.; Hahn, H.T.

2003-01-01

The curvature of unsymmetrical [0/90] laminates moulded from AS4/8552 uni-directional tape has been measured. A linear thermoelastic approach has been applied to predict the related residual stress state before demoulding, giving an estimate of the stress induced by polymerisation strain. The
Influence of Welding Strength Matching Coefficient and Cold Stretching on Welding Residual Stress in Austenitic Stainless Steel

Science.gov (United States)

Lu, Yaqing; Hui, Hu; Gong, Jianguo

2018-05-01

Austenitic stainless steel is widely used in pressure vessels for the storage and transportation of liquid gases such as liquid nitrogen, liquid oxygen, and liquid hydrogen. Cryogenic pressure vessel manufacturing uses cold stretching technology, which relies heavily on welding joint performance, to construct lightweight and thin-walled vessels. Residual stress from welding is a primary factor in cases of austenitic stainless steel pressure vessel failure. In this paper, on the basis of Visual Environment 10.0 finite element simulation technology, the residual stress resulting from different welding strength matching coefficients (0.8, 1, 1.2, 1.4) for two S30408 plates welded with three-pass butt welds is calculated according to thermal elastoplastic theory. In addition, the stress field was calculated under a loading as high as 410 MPa and after the load was released. Path 1 was set to analyze stress along the welding line, and path 2 was set to analyze stress normal to the welding line. The welding strength matching coefficient strongly affected both the longitudinal residual stress (center of path 1) and the transverse residual stress (both ends of path 1) after the welding was completed. However, the coefficient had little effect on the longitudinal and transverse residual stress of path 2. Under the loading of 410 MPa, the longitudinal and transverse stress decreased and the stress distribution, with different welding strength matching coefficients, was less diverse. After the load was released, longitudinal and transverse stress distribution for both path 1 and path 2 decreased to a low level. Cold stretching could reduce the effect of residual stress to various degrees. Transverse strain along the stretching direction was also taken into consideration. The experimental results validated the reliability of the partial simulation.
Mechanical Characterization of Thermomechanical Matrix Residual Stresses Incurred During MMC Processing

Science.gov (United States)

Castelli, Michael G.

1998-01-01

In recent years, much effort has been spent examining the residual stress-strain states of advanced composites. Such examinations are motivated by a number of significant concerns that affect composite development, processing, and analysis. The room-temperature residual stress states incurred in many advanced composite systems are often quite large and can introduce damage even prior to the first external mechanical loading of the material. These stresses, which are induced during the cooldown following high-temperature consolidation, result from the coefficient of thermal expansion mismatch between the fiber and matrix. Experimental techniques commonly used to evaluate composite internal residual stress states are non-mechanical in nature and generally include forms of x-ray and neutron diffraction. Such approaches are usually complex, involving a number of assumptions and limitations associated with a wide range of issues, including the depth of penetration, the volume of material being assessed, and erroneous effects associated with oriented grains. Furthermore, and more important to the present research, these techniques can assess only "single time" stress in the composite. That is, little, if any, information is obtained that addresses the time-dependent point at which internal stresses begin to accumulate, the manner in which the accumulation occurs, and the presiding relationships between thermoelastic, thermoplastic, and thermoviscous behaviors. To address these critical issues, researchers at the NASA Lewis Research Center developed and implemented an innovative mechanical test technique to examine in real time, the time-dependent thermomechanical stress behavior of a matrix alloy as it went through a consolidation cycle.
Effect of prior machining deformation on the development of tensile residual stresses in weld-fabricated nuclear components

International Nuclear Information System (INIS)

Prevey, P.S.; Mason, P.W.; Hornbach, D.J.; Molkenthin, J.P.

1996-01-01

Austenitic alloy weldments in nuclear systems may be subject to stress-corrosion cracking (SCC) failure if the sum of residual and applied stresses exceeds a critical threshold. Residual stresses developed by prior machining and welding may either accelerate or retard SCC, depending on their magnitude and sign. A combined x-ray diffraction and mechanical procedure was used to determine the axial and hoop residual stress and yield strength distributions into the inside-diameter surface of a simulated Alloy 600 penetration J-welded into a reactor pressure vessel. The degree of cold working and the resulting yield strength increase caused by prior machining and weld shrinkage were calculated from the line-broadening distributions. Tensile residual stresses on the order of +700 MPa were observed in both the axial and the hoop directions at the inside-diameter surface in a narrow region adjacent to the weld heat-affected zone. Stresses exceeding the bulk yield strength were found to develop due to the combined effects of cold working of the surface layers during initial machining and subsequent weld shrinkage. The residual stress and cold work distributions produced by prior machining were found to influence strongly the final residual stress state developed after welding

Influence of weld-induced residual stresses on the hysteretic behavior of a girth-welded circular stainless steel tube

Science.gov (United States)

Lee, Chin-Hyung; Nguyen Van Do, Vuong; Chang, Kyong-Ho; Jeon, Jun-Tai; Um, Tae-Hwan

2018-04-01

The present study attempts to characterize the relevance of welding residual stresses to the hysteretic behaviour of a girth-welded circular stainless steel tube under cyclic mechanical loadings. Finite element (FE) thermal simulation of the girth butt welding process is first performed to identify the weld-induced residual stresses by using the one-way coupled three-dimensional (3-D) thermo-mechanical FE analysis method. 3-D elastic-plastic FE analysis equipped with the cyclic plasticity constitutive model capable of describing the cyclic response is next carried out to scrutinize the effects that the residual stresses have on the hysteretic performance of the girth-welded steel tube exposed to cyclic axial loading, which takes the residual stresses and plastic strains calculated from the preceding thermo-mechanical analysis as the initial condition. The analytical results demonstrate that the residual stresses bring about premature yielding and deterioration of the load carrying capacity in the elastic and the transition load ranges, whilst the residual stress effect is wiped out quickly in the plastic load domain since the residual stresses are nearly wholly relaxed after application of the cyclic plastic loading.
Residual stresses in a cast iron automotive brake disc rotor

International Nuclear Information System (INIS)

Ripley, Maurice I.; Kirstein, Oliver

2006-01-01

Runout, and consequent juddering and pulsation through the brake pedal, is a multi-million dollar per year warranty problem for car manufacturers. There is some suspicion that the runout can be caused by relaxation of residual casting stresses when the disc is overheated during severe-braking episodes. We report here neutron-diffraction measurements of the levels and distribution of residual strains in a used cast iron brake disc rotor. The difficulties of measuring stresses in grey cast iron are outlined and three-dimensional residual-strain distributions are presented and their possible effects discussed
Residual stress improved by water jet peening using cavitation for small-diameter pipe inner surfaces

International Nuclear Information System (INIS)

Yasuo, Nakamura; Toshizo, Ohya; Koji, Okimura

2001-01-01

As one of degradation conditions on components used in water, the overlapping effect of environment, material and stress might cause stress corrosion cracking (SCC). Especially, for the tensile residual stress produced by welding, it is particularly effective to reduce the tensile residual stress on the material surface to prevent SCC. In this paper, the residual stress improvement method using cavitation impact generated by a water jet, called Water Jet Peening (WJP), has been developed as the maintenance technology for the inner surfaces of small-diameter Ni-Cr-Fe alloy (Alloy 600) pipes. As the results, by WJP for the inner surface of Alloy 600 pipe (inner diameter; approximately 10-15 mm), we confirmed that the compressive stress generated within the range from the surface to the inner part about 0.5 mm deep and took a maximum value about 350 MPa on the surface. (author)
Numerical weld modeling - a method for calculating weld-induced residual stresses

International Nuclear Information System (INIS)

Fricke, S.; Keim, E.; Schmidt, J.

2001-01-01

In the past, weld-induced residual stresses caused damage to numerous (power) plant parts, components and systems (Erve, M., Wesseling, U., Kilian, R., Hardt, R., Bruemmer, G., Maier, V., Ilg, U., 1994. Cracking in Stabilized Austenitic Stainless Steel Piping of German Boiling Water Reactors - Characteristic Features and Root Causes. 20. MPA-Seminar 1994, vol. 2, paper 29, pp.29.1-29.21). In the case of BWR nuclear power plants, this damage can be caused by the mechanism of intergranular stress corrosion cracking in austenitic piping or the core shroud in the reactor pressure vessel and is triggered chiefly by weld-induced residual stresses. One solution of this problem that has been used in the past involves experimental measurements of residual stresses in conjunction with weld optimization testing. However, the experimental analysis of all relevant parameters is an extremely tedious process. Numerical simulation using the finite element method (FEM) not only supplements this method but, in view of modern computer capacities, is also an equally valid alternative in its own right. This paper will demonstrate that the technique developed for numerical simulation of the welding process has not only been properly verified and validated on austenitic pipe welds, but that it also permits making selective statements on improvements to the welding process. For instance, numerical simulation can provide information on the starting point of welding for every weld bead, the effect of interpass cooling as far as a possible sensitization of the heat affected zone (HAZ) is concerned, the effect of gap width on the resultant weld residual stresses, or the effect of the 'last pass heat sink welding' (welding of the final passes while simultaneously cooling the inner surface with water) producing compressive stresses in the root area of a circumferential weld in an austenitic pipe. The computer program FERESA (finite element residual stress analysis) was based on a commercially
Feasibility of ultrasonic and eddy current methods for measurement of residual stress in shot peened metals

International Nuclear Information System (INIS)

Lavrentyev, Anton I.; Stucky, Paul A.; Veronesi, William A.

2000-01-01

Shot peening is a well-known method for extending the fatigue life of metal components by introducing compressive residual stresses near their surfaces. The capability to nondestructively evaluate the near surface residual stress would greatly aid the assurance of proper fatigue life in shot-peened components. This paper presents preliminary results from a feasibility study examining the use of ultrasonic and eddy current NDE methods for residual stress measurement in components where the stress has been introduced by shot peening. With an ultrasonic method, a variation of ultrasonic surface wave speed with shot peening intensity was measured. Near surface conductivity was measured by eddy current methods. Since the effective penetration depth of both methods employed is inversely related to the excitation frequency, by making measurements at different frequencies, each method has the potential to provide the stress-depth profile. Experiments were conducted on aluminum specimens (alloy 7075-T7351) peened within the Almen peening intensity range of 4C to 16C. The experimental results obtained demonstrate a correlation between peening intensity and Rayleigh wave velocity and between peening intensity and conductivity. The data suggests either of the methods may be suitable, with limitations, for detecting unsatisfactory levels of shot peening. Several factors were found to contribute to the measured responses: surface roughness, near surface plastic deformation (cold work) and residual stress. The contribution of each factor was studied experimentally. The feasibility of residual stress determination from the measured data is discussed
Residual Stress Distribution In Heat Affected Zone Of Welded Steel By Means Of Neutron Diffraction Method

International Nuclear Information System (INIS)

Fajar, Andika; Prasuad; Gunawan; Muslich, M. Rifai

1996-01-01

Three dimensional residual stress distribution in the heat affected zone of 10 mm thick welded steel by means of neutron diffraction technique has been measured. The results showed that the residual stress was distributed near the welded metal, namely within about 46,25 mm. The major tensile stresses occurred in the X-direction, and they attained a level greater than 2000 MPa through the position far away fram the weld. The tensile stresses in the Y and Z- directions lied between 500 and 1500 MPa, The results also suggest that the stress in the surface was greater than that in the middle of the sample
Remarks on Residual Stress Measurement by Hole-Drilling and Electronic Speckle Pattern Interferometry

Directory of Open Access Journals (Sweden)

Claudia Barile

2014-01-01

Full Text Available Hole drilling is the most widespread method for measuring residual stress. It is based on the principle that drilling a hole in the material causes a local stress relaxation; the initial residual stress can be calculated by measuring strain in correspondence with each drill depth. Recently optical techniques were introduced to measure strain; in this case, the accuracy of the final results depends, among other factors, on the proper choice of the area of analysis. Deformations are in fact analyzed within an annulus determined by two parameters: the internal and the external radius. In this paper, the influence of the choice of the area of analysis was analysed. A known stress field was introduced on a Ti grade 5 sample and then the stress was measured in correspondence with different values of the internal and the external radius of analysis; results were finally compared with the expected theoretical value.
The influence of quench sensitivity on residual stresses in the aluminium alloys 7010 and 7075

International Nuclear Information System (INIS)

Robinson, J.S.; Tanner, D.A.; Truman, C.E.; Paradowska, A.M.; Wimpory, R.C.

2012-01-01

The most critical stage in the heat treatment of high strength aluminium alloys is the rapid cooling necessary to form a supersaturated solid solution. A disadvantage of quenching is that the thermal gradients can be sufficient to cause inhomogeneous plastic deformation which in turn leads to the development of large residual stresses. Two 215 mm thick rectilinear forgings have been made from 7000 series alloys with widely different quench sensitivity to determine if solute loss in the form of precipitation during quenching can significantly affect residual stress magnitudes. The forgings were heat treated and immersion quenched using cold water to produce large magnitude residual stresses. The through thickness residual stresses were measured by neutron diffraction and incremental deep hole drilling. The distribution of residual stresses was found to be similar for both alloys varying from highly triaxial and tensile in the interior, to a state of biaxial compression in the surface. The 7010 forging exhibited larger tensile stresses in the interior. The microstructural variation from surface to centre for both forgings was determined using optical and transmission electron microscopy. These observations were used to confirm the origin of the hardness variation measured through the forging thickness. When the microstructural changes were accounted for in the through thickness lattice parameter, the residual stresses in the two forgings were found to be very similar. Solute loss in the 7075 forging appeared to have no significant effect on the residual stress magnitudes when compared to 7010. - Highlights: ► Through thickness residual stress measurements made on large Al alloy forgings. ► Residual stress characterised using neutron diffraction and deep hole drilling. ► Biaxial compressive surface and triaxial subsurface residual stresses. ► Quench sensitivity of 7075 promotes significant microstructural differences to 7010. ► When precipitation is
Residual stress measurement on propellant tank of 2219 aluminum alloy and study on its weak spot

Energy Technology Data Exchange (ETDEWEB)

Huang, Chaoqun; Li, Huan; Li, Jianxiong; Luo, Chuanguang; Ni, Yanbing [Tianjin University, Tianjin (China)

2017-05-15

This paper presented residual stress measurement on two circumferential Variable polarity plasma arc welding (VPPAW) joints and one circular closed Friction stir welding (FSW) joint on the propellant tank of 2219 aluminum alloy using the indentation strain-gauge method. Quite large tensile residual stresses were attached to the center and inner areas of the circular closed FSW joint. There were very large tensile stresses in some points of the two circumferential VPPAW joints, among these points, the maximum value was +253 MPa, which was about 63 % of the yield strength of 410 MPa measured in the base material. In addition, the peak of compressive residual stress was about -160 MPa. Above all, there were two typical peaks of residual stress in the circumferential VPPAW joints, one was located in the middle part while the other one was near the start/end position of the joints. Combining the result of residual stress measurement with the characteristics of the tank structure, it can be concluded that circular closed FSW joint around the flange was a weak spot on the propellant tank. And the most vulnerable point on the circular closed FSW joint has also been found.
A study for high accuracy measurement of residual stress by deep hole drilling technique

Science.gov (United States)

Kitano, Houichi; Okano, Shigetaka; Mochizuki, Masahito

2012-08-01

The deep hole drilling technique (DHD) received much attention in recent years as a method for measuring through-thickness residual stresses. However, some accuracy problems occur when residual stress evaluation is performed by the DHD technique. One of the reasons is that the traditional DHD evaluation formula applies to the plane stress condition. The second is that the effects of the plastic deformation produced in the drilling process and the deformation produced in the trepanning process are ignored. In this study, a modified evaluation formula, which is applied to the plane strain condition, is proposed. In addition, a new procedure is proposed which can consider the effects of the deformation produced in the DHD process by investigating the effects in detail by finite element (FE) analysis. Then, the evaluation results obtained by the new procedure are compared with that obtained by traditional DHD procedure by FE analysis. As a result, the new procedure evaluates the residual stress fields better than the traditional DHD procedure when the measuring object is thick enough that the stress condition can be assumed as the plane strain condition as in the model used in this study.
Measuring multiple residual-stress components using the contour method and multiple cuts

Energy Technology Data Exchange (ETDEWEB)

Prime, Michael B [Los Alamos National Laboratory; Swenson, Hunter [Los Alamos National Laboratory; Pagliaro, Pierluigi [U. PALERMO; Zuccarello, Bernardo [U. PALERMO

2009-01-01

The conventional contour method determines one component of stress over the cross section of a part. The part is cut into two, the contour of the exposed surface is measured, and Bueckner's superposition principle is analytically applied to calculate stresses. In this paper, the contour method is extended to the measurement of multiple stress components by making multiple cuts with subsequent applications of superposition. The theory and limitations are described. The theory is experimentally tested on a 316L stainless steel disk with residual stresses induced by plastically indenting the central portion of the disk. The stress results are validated against independent measurements using neutron diffraction. The theory has implications beyond just multiple cuts. The contour method measurements and calculations for the first cut reveal how the residual stresses have changed throughout the part. Subsequent measurements of partially relaxed stresses by other techniques, such as laboratory x-rays, hole drilling, or neutron or synchrotron diffraction, can be superimposed back to the original state of the body.
X-ray evaluation of residual stress distributions within surface machined layer generated by surface machining and sequential welding

International Nuclear Information System (INIS)

Taniguchi, Yuu; Okano, Shigetaka; Mochizuki, Masahito

2017-01-01

The excessive tensile residual stress generated by welding after surface machining may be an important factor to cause stress corrosion cracking (SCC) in nuclear power plants. Therefore we need to understand and control the residual stress distribution appropriately. In this study, residual stress distributions within surface machined layer generated by surface machining and sequential welding were evaluated by X-ray diffraction method. Depth directional distributions were also investigated by electrolytic polishing. In addition, to consider the effect of work hardened layer on the residual stress distributions, we also measured full width at half maximum (FWHM) obtained from X-ray diffraction. Testing material was a low-carbon austenitic stainless steel type SUS316L. Test specimens were prepared by surface machining with different cutting conditions. Then, bead-on-plate welding under the same welding condition was carried out on the test specimens with different surface machined layer. As a result, the tensile residual stress generated by surface machining increased with increasing cutting speed and showed nearly uniform distributions on the surface. Furthermore, the tensile residual stress drastically decreased with increasing measurement depth within surface machined layer. Then, the residual stress approached 0 MPa after the compressive value showed. FWHM also decreased drastically with increasing measurement depth and almost constant value from a certain depth, which was almost equal regardless of the machining condition, within surface machined layer in all specimens. After welding, the transverse distribution of the longitudinal residual stress varied in the area apart from the weld center according to machining conditions and had a maximum value in heat affected zone. The magnitude of the maximum residual stress was almost equal regardless of the machining condition and decreased with increasing measurement depth within surface machined layer. Finally, the
Distortion and residual stresses in structures reinforced with titanium straps for improved damage tolerance

International Nuclear Information System (INIS)

Liljedahl, C.D.M.; Fitzpatrick, M.E.; Edwards, L.

2008-01-01

Distortion and residual stresses induced during the manufacturing process of bonded crack retarders have been investigated. Titanium alloy straps were adhesively bonded to an aluminium alloy SENT specimen to promote fatigue crack growth retardation. The effect of three different strap dimensions was investigated. The spring-back of a component when released from the autoclave and the residual stresses are important factors to take into account when designing a selective reinforcement, as this may alter the local aerodynamic characteristics and reduce the crack bridging effect of the strap. The principal problem with residual stresses is that the tensile nature of the residual stresses in the primary aluminium structure has a negative impact on the crack initiation and crack propagation behaviour in the aluminium. The residual stresses were measured with neutron diffraction and the distortion of the specimens was measured with a contour measurement machine. The bonding process was simulated with a three-dimensional FE model. The residual stresses were found to be tensile close to the strap and slightly compressive on the un-bonded side. Both the distortion and the residual stresses increased with the thickness and the width of the strap. Very good agreement between the measured stresses and the measured distortion and the FE simulation was found
NUMERICAL SIMULATION OF RESIDUAL STRESSES GENERATED IN THE WIRE DRAWING PROCESS FOR DIFFERENT PROCESS PARAMETERS

Directory of Open Access Journals (Sweden)

Juliana Zottis

2014-03-01

Full Text Available The drawing process of steel bars is usually used to check better dimensional accuracy and mechanical properties to the material. In the other hand, the major concern found in manufacturing axes through this process is the appearance of distortion of shape. Such distortions are directly linked to the accumulation of residual stresses generated during the processes. As a result, this paper aims to study the influence of process parameters such as shape of puller, speed and lubrication used in wire drawing analyzing the accumulation of residual stress after the process. The stress analysis was performed by FEM being used two simulation software: Simufact.formingGP and DeformTM. Through these analyzes, it was found that the shape of how the bar is pulled causes a reduction of up to 100 MPa in residual stresses in the center of the bar, which represents an important factor in the study of the possible causes of the distortion. As well as factors speed and homogeneity of lubrication significantly altered the profile of residual stresses in the bar.
X-ray measurement of residual stress in metals at Chalk River Nuclear Laboratories

International Nuclear Information System (INIS)

Winegar, J.E.

1980-06-01

X-ray diffraction is used at CRNL to measure residual stress in metals. This report summarizes the basic principles of stress measurement, and reviews factors affecting accuracy of measurement. The technique and equipment described were developed at CRNL to give reliable measurements. Accuracy of measurement is achieved by using fixed-count step-scanning and by computer analysis of intensity data using a cubic spline curve smoothing routine. Specific reference is made to the measurement of residual stress in Inconel-600 and Incoloy-800 boiler tubing. Because it measures stress in thin surface layers, the X-ray method can also be used to measure the depth profile of stresses. As there are no standardized procedures for measuring residual stress, this report will be useful both to those unfamiliar with the measurement of residual stress and to those already making such measurements in other laboratories. (auth)
On the role of the residual stress state in product manufacturing

NARCIS (Netherlands)

Zijlstra, G.; Groen, M.; Post, J.; Ocelik, V.; de Hosson, J.Th.M.

2016-01-01

This paper concentrates on the effect of the residual stress state during product manufacturing of AISI 420 steel on the final shape of the product. The work includes Finite Element (FE) calculations of the distribution of the residual stresses after metal forming and a heat treatment. The evolution
Determination of global and local residual stresses in SOFC by X-ray diffraction

International Nuclear Information System (INIS)

Villanova, Julie; Sicardy, Olivier; Fortunier, Roland; Micha, Jean-Sebastien; Bleuet, Pierre

2010-01-01

Solid Oxide Fuel Cell (SOFC) is a high-performance electrochemical device for energy conversion. A single cell is composed of five layers made of different ceramic materials: anode support, anode functional layer, electrolyte, cathode functional layer and cathode. The mechanical integrity of the cell is a major issue during its lifetime, especially for the electrolyte layer. Damage of the cells is mainly due to the high operating temperature, the 'redox' behaviour of the anode and the brittleness of the involved materials. Since residual stresses are known to play a significant role in the damage evolution, it is important to determine them. For this purpose, residual stresses in an anode-supported planar SOFC were measured by X-ray diffraction. Firstly, macroscopic stresses in each phase of each layer were studied using the sin 2 ψ method on a laboratory X-ray goniometer at room temperature. This technique enables the calculation of residual stress of the material from the measurement of the crystal lattice deformation. The electrolyte has been found under bi-axial compressive stress of -920 MPa. Secondly, X-ray measurements controlling depth penetration were made in the electrolyte using grazing incidence method. The results show that the stress is not homogenous in the layer. The first five micrometers of the electrolyte have been found less constrained (-750 MPa) than the complete layer, suggesting a gradient of deformation in the electrolyte from the interface with the Anode Functional Layer to the free surface. Finally, local stress measurements were made on the electrolyte layer by X-ray synchrotron radiation that allows high accuracy measurement on the (sub-) micrometer scale. Polychromatic and monochromatic beams are used to determine the complete strain tensor from grain to grain in the electrolyte. First results confirm the macroscopic stress trend of the electrolyte. These X-ray techniques at different scales will contribute to a better understanding
Residual stresses relaxation in surface-hardened half-space under creep conditions

Directory of Open Access Journals (Sweden)

Vladimir P. Radchenko

2015-09-01

Full Text Available We developed the method for solving the problem of residual stresses relaxation in surface-hardened layer of half-space under creep conditions. At the first stage we made the reconstruction of stress-strain state in half-space after plastic surface hardening procedure based on partial information about distribution for one residual stress tensor component experimentally detected. At the second stage using a numerical method we solve the problem of relaxation of self-balanced residual stresses under creep conditions. To solve this problem we introduce the following Cartesian system: x0y plane is aligned with hardened surface of half-space and 0z axis is directed to the depth of hardened layer. We also introduce the hypotheses of plane sections parallel to x0z and y0z planes. Detailed analysis of the problem has been done. Comparison of the calculated data with the corresponding test data was made for plane specimens (rectangular parallelepipeds made of EP742 alloy during T=650°C after the ultrasonic hardening with four hardening modes. We use half-space to model these specimens because penetration's depth of residual stresses is less than specimen general size in two digit exponent. There is enough correspondence of experimental and calculated data. It is shown that there is a decay (in modulus of pressing residual stresses under creep in 1.4–1.6 times.
Prediction of residual stresses in the heat affected zone

International Nuclear Information System (INIS)

Taleb, L.; Petit, S.; Jullien, J.F.

2004-01-01

In this paper the behavior of a disc made up of carbon manganese steel and subjected to an axisymmetric heating in its middle zone is considered. The applied thermal cycle generates localized metallurgical solid-solid phase transformations. Contrary to the study performed some years ago, the present work is concerned with relatively thick discs that lead to variable behavior according to axial direction. Experimentally, temperature and axial displacement of the face below have continuously been measured during tests. At the end of tests, the nature and the proportions of the final phases as well as residual stresses on both faces of the discs has also been assessed. These experimental results have been compared to numerical simulations using the finite element code ASTER, developed by EDF (Electricity of France), ASTER enables us to take into account the main mechanical consequences of phase transformations. From the obtained results it can be pointed out the significant importance to take into account the transformation induced plasticity (TRIP) phenomenon for better estimation of residual stresses. (authors)
The effects of location, thermal stress, and residual stress on corner cracks in nozzles with cladding

International Nuclear Information System (INIS)

Besuner, P.M.; Cohen, L.M.; McLean, J.L.

1977-01-01

The stress intensity factors (Ksub(I)) for corner cracks in a boiling water reactor feedwater nozzle with stainless steel cladding are obtained for loading by internal pressure, and a fluid quench in the nozzle. Conditions with and without residual stress in the component are considered. The residual stress is simulated by means of a reference temperature change. The stress distribution for the uncracked structure is obtained from a three-dimensional finite element model. A three-dimensional influence function (IF) method, in conjunction with the boundary-integral equation method for structural analysis, is employed to compute Ksub(I) values from the uncracked structure's stress distribution. For each type of loading Ksub(I) values are given for cracks at 15 nozzle locations and for six crack depths. Reasonable agreement is noted between calculated and previously published pressure-induced Ksub(I) values. Comparisons are made to determine the effect on Ksub(I) of crack location, thermal stress, and residual stress as compared to pressure stress. For the thermal transient it is shown that Ksub(I) for small crack depths is maximized early in the transient while Ksub(I) for large cracks is maximized later, under steady state conditions. Ksub(I) computations should, therefore, be made for several transient time points and the maximum Ksub(I) for a given crack depth should be used for design analysis. It is concluded that the effects on Ksub(I) of location, thermal stresses, and residual stresses are significant and generally too complex to evalute without advanced numerical procedures. The utilized combination of finite element analysis of the uncracked structure and three-dimensional influence function analysis of the cracked structure is demonstrated

Analytical description of fatigue crack propagation regularities taking into account residual welding stresses

International Nuclear Information System (INIS)

Trufyakov, V.I.; Knysh, V.V.; Mikheev, P.P.; Kuz'menko, A.Z.

1983-01-01

The procedure, accounting the effect of residual stresses on crack resistance of welded constructions under cyclic loads, is described. The procedure is based on the Paris equation modified by the introduction of the coefficient of residual stress intensity through the functional dependence. The dependence is determined for cases of residual stresses of tension and compression. The experimental data for the 15KhSND steel are presented
Measurement of heat treatment induced residual stresses by using ESPI combined with hole-drilling method

Directory of Open Access Journals (Sweden)

Jie Cheng

2010-08-01

Full Text Available In this study, residual stresses in heat treated specimen were measured by using ESPI (Electronic Speckle-Pattern Interferometry combined with the hole-drilling method. The specimen, made of SUS 304 austenitic stainless steel, was quenched and water cooled to room temperature. Numerical simulation using a hybrid FDM/FEM package was also carried out to simulate the heat treatment process. As a result, the thermal stress fields were obtained from both the experiment and the numerical simulation. By comparision of stress fields, results from the experimental method and numerical simulation well agreed to each other, therefore, it is proved that the presented experimental method is applicable and reliable for heat treatment induced residual stress measurement.
Modelling and experimental characterisation of a residual stress field in a ferritic compact tension specimen

International Nuclear Information System (INIS)

Wenman, M.R.; Price, A.J.; Steuwer, A.; Chard-Tuckey, P.R.; Crocombe, A.

2009-01-01

The aim of the work is to elucidate the influence of plasticity behaviour on the residual stress field in a ferritic reactor pressure vessel steel. To this end, we investigate two compressively pre-loaded compact tension (CT) specimens to generate a mechanical residual stress field. One specimen was subsequently pre-cracked by fatigue before both specimens were measured using high-energy synchrotron X-ray diffraction. A fine grain size microstructure (∼5-10 μm grain size) allowed a small X-ray beam slit size and therefore gauge volume. The results provide an excellent data set for validation of finite element (FE) modelling predictions against which they have been compared. The results of both mechanical testing and modelling suggest that the use of a combined hardening model is needed to accurately predict the residual stress field present in the specimen after pre-loading. Some discrepancy between the modelled crack tip stress values and those found by X-ray diffraction remain which can be partly explained by volume averaging effects in the presence of very high stress/strain gradients.
Modelling and experimental characterisation of a residual stress field in a ferritic compact tension specimen

Energy Technology Data Exchange (ETDEWEB)

Wenman, M.R., E-mail: m.wenman@imperial.ac.u [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); Price, A.J. [Faculty of Engineering and Physical Sciences (J5), University of Surrey, Guildford GU2 7XH (United Kingdom); Steuwer, A. [ESS Scandinavia, Stora Algatan 4, 22350 Lund (Sweden) and Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Chard-Tuckey, P.R. [Nuclear Department, Defence College of Management and Technology, HMS Sultan, Gosport, Hants PO12 3BY (United Kingdom); Crocombe, A. [Faculty of Engineering and Physical Sciences (J5), University of Surrey, Guildford GU2 7XH (United Kingdom)

2009-12-15

The aim of the work is to elucidate the influence of plasticity behaviour on the residual stress field in a ferritic reactor pressure vessel steel. To this end, we investigate two compressively pre-loaded compact tension (CT) specimens to generate a mechanical residual stress field. One specimen was subsequently pre-cracked by fatigue before both specimens were measured using high-energy synchrotron X-ray diffraction. A fine grain size microstructure (approx5-10 mum grain size) allowed a small X-ray beam slit size and therefore gauge volume. The results provide an excellent data set for validation of finite element (FE) modelling predictions against which they have been compared. The results of both mechanical testing and modelling suggest that the use of a combined hardening model is needed to accurately predict the residual stress field present in the specimen after pre-loading. Some discrepancy between the modelled crack tip stress values and those found by X-ray diffraction remain which can be partly explained by volume averaging effects in the presence of very high stress/strain gradients.
RESIDUAL STRESS MEASUREMENTS AND STRUCTURAL INTEGRITY IMPLICATIONS FOR SELECTIVE LASER MELTED TI-6AL-4V

Directory of Open Access Journals (Sweden)

Knowles, C. R.

2012-11-01

Full Text Available Selective laser melting (SLM of Ti-6Al-4V has significant potential in the aerospace and biotechnology industries. SLM employs a focused laser beam to melt successive layers of metallic powder into complex components. This process can result in the generation of high thermally-induced residual stresses. These residual stresses, together with micro-flaws/ pores from the inherent fabrication process, may lead to premature fatigue crack initiation and propagation at relatively low cyclic stresses. The hole-drilling strain gauge method was used to evaluate residual stresses within SLM Ti-6Al-4V specimens, with the intention of understanding the associated mechanisms for the successful application of SLM Ti-6Al-4V in industry.
Effect of processing conditions and methods on residual stress in CeO2 buffer layers and YBCO superconducting films

International Nuclear Information System (INIS)

Xiong Jie; Qin Wenfeng; Cui Xumei; Tao Bowan; Tang Jinlong; Li Yanrong

2006-01-01

CeO 2 layers have been fabricated by pulsed laser deposition (PLD) technique on (1 1 0 2) sapphire substrate. Microstructure of CeO 2 layers is characterized by X-ray diffraction as functions of substrate temperature. The effects of the substrate temperature on the residual stress have been studied. The results show that residual stress in CeO 2 film decreased with increasing substrate temperature, not the same development tendency as that of thermal stress. This means that the thermal stress is only a fraction of the residual stress. Moreover, YBCO superconducting films were prepared by direct current (DC) sputtering and pulsed laser deposition (PLD) technique. The residual stress and thermal stress of both YBCO films were measured. PLD processing apparently generated higher intrinsic compressive stresses in comparison to DC sputtering
Study of residual stresses generated in machining of AISI 4340 steel

International Nuclear Information System (INIS)

Reis, W.P. dos; Fonseca, M.P. Cindra; Serrao, L.F.; Chuvas, T.C.; Oliveira, L.C.

2010-01-01

Among the mechanical construction steels, AISI 4340 has good harden ability, while combining high strength with toughness and good fatigue strength, making it excellent for application in the metalworking industry, where it can work at different levels and types of requests. Residual stresses are generated in almost all processes of mechanical manufacturing. In this study, the residual stresses generated in different machining processes and heat treatment hardening of AISI 4340 were analyzed by X-ray diffraction, by the sen 2 ψ method, using Crκβ radiation and compared. All samples, except for turned and cut by EDM, presented compressive residual stresses in the surface with various magnitudes. (author)
Residual stress behaviors induced by laser peening along the edge of curved models

International Nuclear Information System (INIS)

Im, Jong Bin; Grandhi, Ramana V.; Ro, Young Hee

2012-01-01

Laser peening (LP) induces high magnitude compressive residual stresses in a small region of a component. The compressive residual stresses cause plastic deformation that is resistant to fatigue fracture. Fatigue cracks are generally nucleated at critical areas, and LP is applied for those regions so as to delay the crack initiation. Many critical regions are located on the edge of the curved portion of structures because of stress concentration effects. Several investigations that are available for straight components may not give meaningful guidelines for peening curved components. Therefore, in this paper, we investigate residual stress behaviors induced by LP along the edge of curved models. Three curved models that have different curvatures are investigated for peening performance. Two types of peening configurations, which are simultaneous corner shot and sequential corner shots, are considered in order to obtain compressive residual stresses along an edge. LP simulations of multiple shots are performed to identify overlapping effects on the edge portion of a curved model. In addition, the uncertainty calculation of residual stress induced by LP considering laser pulse duration is performed
Standard test method for determining residual stresses by the hole-drilling strain-gage method

CERN Document Server

American Society for Testing and Materials. Philadelphia

2008-01-01

1.1 Residual Stress Determination: 1.1.1 This test method specifies a hole-drilling procedure for determining residual stress profiles near the surface of an isotropic linearly elastic material. The test method is applicable to residual stress profile determinations where in-plane stress gradients are small. The stresses may remain approximately constant with depth (“uniform” stresses) or they may vary significantly with depth (“non-uniform” stresses). The measured workpiece may be “thin” with thickness much less than the diameter of the drilled hole or “thick” with thickness much greater than the diameter of the drilled hole. Only uniform stress measurements are specified for thin workpieces, while both uniform and non-uniform stress measurements are specified for thick workpieces. 1.2 Stress Measurement Range: 1.2.1 The hole-drilling method can identify in-plane residual stresses near the measured surface of the workpiece material. The method gives localized measurements that indicate the...
Residual Stress Analysis for Engineering Applications by Means of Neutron Diffraction

International Nuclear Information System (INIS)

Gndupel-Herold, Thomas; Brand, Paul C.; Prask, Henry J.

1999-01-01

The economic and scientific importance of neutron diffraction residual stress analysis has led to an increasing number of suitable instruments worldwide. Recently, a dedicated state-of-the-art diffractometer has been installed at the National Institute of Standards and Technology reactor. It has been used for a variety of measurements on basic and engineering stress problems. Among the most prominent examples that have been investigated are residual stresses in rails, weldments, and plasma-sprayed coatings
A Thermodamage Strength Theoretical Model of Ceramic Materials Taking into Account the Effect of Residual Stress

Directory of Open Access Journals (Sweden)

Weiguo Li

2012-01-01

Full Text Available A thermodamage strength theoretical model taking into account the effect of residual stress was established and applied to each temperature phase based on the study of effects of various physical mechanisms on the fracture strength of ultrahigh-temperature ceramics. The effects of SiC particle size, crack size, and SiC particle volume fraction on strength corresponding to different temperatures were studied in detail. This study showed that when flaw size is not large, the bigger SiC particle size results in the greater effect of tensile residual stress in the matrix grains on strength reduction, and this prediction coincides with experimental results; and the residual stress and the combined effort of particle size and crack size play important roles in controlling material strength.
A neutron diffraction study of residual stress and plastic strain in welded beryllium rings

Energy Technology Data Exchange (ETDEWEB)

Brown, D.W.; Varma, R.; Bourke, M.A.M.; Holden, T.M. [Los Alamos National Lab., Los Alamos, NM (United States); Ely, T.; Spooner, S. [Oak Ridge National Lab., Oak Ridge, TN (United States)

2002-07-01

We present a study of residual stresses associated with the welding of beryllium rings. Using novel analysis techniques, information about residual stresses and plastic deformation of the base metal were obtained. In the post-welded state, the rings have a strong tensile circumferential residual stress and show evidence of significant plastic deformation. (orig.)
A study on the bonding residual thermal stress analysis of dissimilar materials using boundary element method

International Nuclear Information System (INIS)

Yi, Won; Yu, Yeong Chul; Jeong, Eui Seob; Lee, Chang Ho

1995-01-01

It is very important to evaluate the bonding residual thermal stress in dissimilar materials such as LSI package. In this study, the bonding residual thermal stress was calculated using the boundary element method, varing with the sub-element, geometry of specimen and adhesive thickness. The present results reveal a stress singularity at the edge of the interface, therefore the bonding strength of metal/resin interface can be estimated by taking into account it.
Finite element analysis for prediction of the residual stresses induced by shot peening II

International Nuclear Information System (INIS)

Kim, Cheol; Seok, Chang Sung; Yang, Won Ho; Ryu, Myung Hai

2002-01-01

Shot peening is a surface impact treatment widely used to improve the performance of metal parts and welded details subjected to fatigue loading, contact fatigue, stress corrosion and other damage mechanisms. The better performance of the peened parts is mainly due to the residual stresses resulting from the plastic deformation of the surface layers of the material caused by the impact of the shot. In this paper the simulation technique is applied to predict the magnitude and distribution of the residual stress and plastic deformation caused by shot peening with the help of finite element analysis
Residual stress distribution of a 6061-T6 aluminum alloy under shear deformation

International Nuclear Information System (INIS)

Reyes-Ruiz, C.; Figueroa, I.A.; Braham, C.; Cabrera, J.M.; Zanellato, O.; Baiz, S.; Gonzalez, G.

2016-01-01

There is a lack of information with regards to the friction effect in ECAPed aluminum alloys, even though it might substantially modify the deformation at the surface. In this work, the friction effect at the surface and the deformation heterogeneity in the ECAPed aluminum alloy 6061-T6 were characterized. X-Ray diffraction was used to determine residual stresses (RS) on the sample surface. The volumetric sections were characterized by Synchrotron diffraction at ESRF beamline ID15B (Grenoble, France). It was found that the microhardness mapping and residual stress results showed a good agreement with the finite element analysis for the first layer studied. Minor strain variation, Δd/d as a function of (hkl) planes, for the different analyzed sections was found. The study also showed that there was an incomplete symmetry in the residual stress near the surface, even at up to a depth of 400 µm. The regions with higher deformation were found to be at the top and bottom parts of the sample, while the central region showed stress variations of up to 50 MPa.
Residual stress distribution of a 6061-T6 aluminum alloy under shear deformation

Energy Technology Data Exchange (ETDEWEB)

Reyes-Ruiz, C.; Figueroa, I.A. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito exterior S/N, Cd. Universitaria, A.P. 70-360, Coyoacán C.P. 04510 (Mexico); Braham, C. [Laboratoire Procédés et Ingénierie Mécanique et Matériaux, CNRS UMR 8006, ENSAM-CNAM, 151, Bd de l’Hôpital, 75013 Paris (France); Cabrera, J.M. [Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, ETSEIB-Universidad Politécnica de Cataluña, Av Diagonal 647, 08028 Barcelona (Spain); Fundació CTM Centre Tecnológic, Pl. de la Ciencia 2, 08243 Manresa (Spain); Zanellato, O.; Baiz, S. [Laboratoire Procédés et Ingénierie Mécanique et Matériaux, CNRS UMR 8006, ENSAM-CNAM, 151, Bd de l’Hôpital, 75013 Paris (France); Gonzalez, G., E-mail: joseggr@unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito exterior S/N, Cd. Universitaria, A.P. 70-360, Coyoacán C.P. 04510 (Mexico)

2016-07-18

There is a lack of information with regards to the friction effect in ECAPed aluminum alloys, even though it might substantially modify the deformation at the surface. In this work, the friction effect at the surface and the deformation heterogeneity in the ECAPed aluminum alloy 6061-T6 were characterized. X-Ray diffraction was used to determine residual stresses (RS) on the sample surface. The volumetric sections were characterized by Synchrotron diffraction at ESRF beamline ID15B (Grenoble, France). It was found that the microhardness mapping and residual stress results showed a good agreement with the finite element analysis for the first layer studied. Minor strain variation, Δd/d as a function of (hkl) planes, for the different analyzed sections was found. The study also showed that there was an incomplete symmetry in the residual stress near the surface, even at up to a depth of 400 µm. The regions with higher deformation were found to be at the top and bottom parts of the sample, while the central region showed stress variations of up to 50 MPa.
Residual stresses in zircaloy welds

International Nuclear Information System (INIS)

Santisteban, J. R.; Fernandez, L; Vizcaino, P.; Banchik, A.D.; Samper, R; Martinez, R. L; Almer, J; Motta, A.T.; Colas, K.B; Kerr, M.; Daymond, M.R

2009-01-01

Welds in Zirconium-based alloys are susceptible to hydrogen embrittlement, as H enters the material due to dissociation of water. The yield strain for hydride cracking has a complex dependence on H concentration, stress state and texture. The large thermal gradients produced by the applied heat; drastically changes the texture of the material in the heat affected zone, enhancing the susceptibility to delayed hydride cracking. Normally hydrides tend to form as platelets that are parallel to the normal direction, but when welding plates, hydride platelets may form on cooling with their planes parallel to the weld and through the thickness of the plates. If, in addition to this there are significant tensile stresses, the susceptibility of the heat affected zone to delayed hydride cracking will be increased. Here we have measured the macroscopic and microscopic residual stressed that appear after PLASMA welding of two 6mm thick Zircaloy-4 plates. The measurements were based on neutron and synchrotron diffraction experiments performed at the Isis Facility, UK, and at Advanced Photon Source, USA, respectively. The experiments allowed assessing the effect of a post-weld heat treatment consisting of a steady increase in temperature from room temperature to 450oC over a period of 4.5 hours; followed by cooling with an equivalent cooling rate. Peak tensile stresses of (175± 10) MPa along the longitudinal direction were found in the as-welded specimen, which were moderately reduced to (150±10) MPa after the heat-treatment. The parent material showed intergranular stresses of (56±4) MPa, which disappeared on entering the heat-affected zone. In-situ experiments during themal cyclong of the material showed that these intergranular stresses result from the anisotropy of the thermal expansion coefficient of the hexagonal crystal lattice. [es
Evaluation of Residual Stress Distribution and Relaxation on In Situ TiB2/7050 Al Composites

Directory of Open Access Journals (Sweden)

Kunyang Lin

2018-04-01

Full Text Available Interior residual stresses induced by quenching may cause distortion during subsequent machining processes. Hence, various strategies have been employed to relieve the interior residual stress, such as stretching, post treatment, and other techniques. In this study, the stress distribution inside TiB2/7050 Al composite extrusions was investigated and the effects of different methods on relieving the quenching-induced stress were compared. Firstly, three TiB2/7050 Al composite extrusions were treated by stretching, stretching and heat treatment, and stretching and cold treatment processes, respectively. Then, the multiple-cut contour method was employed to assess the residual stresses in the three workpieces. Experimental results indicate that the interior stress of TiB2/7050 Al composite extrusions after stretching ranges from −89 MPa to +55 MPa, which is larger than that in 7050 aluminum alloy, which ranges from −25 Pa to +25 MPa. The heat treatment performs better than the cold treatment to reduce the post-stretching residual stress, with a reduction of 23.2–46.4% compared to 11.3–40.8%, respectively. From the stress map, it is found that the stress distribution after the heat treatment is more uniform compared with that after the cold treatment.
Determination of residual stresses in steel 20 comparison of the results obtained by the Barkhausen noise and X-ray diffraction

International Nuclear Information System (INIS)

Fernandez, L. M.; Herrera, V.; Suarez, J.C.; Merino, F.J.

1997-01-01

During a heat treatment (quenching, surface hardening, Thermochemical treatment) the metallic alloys undergo temperature variations and phase transformation. The resulting changes give rise to internal stresses in the piece. Phase transformation modifies the thermomechanical behavior of the material through the change of mechanical properties ( hardness, fatigue-behaviour, corrosion resistance, electric resistivity, etc.) The aim of this paper is residual stress measurements in specimens of steel-20 submitted to different heat treatment, by two non destructive methods: Barkhausen and X-ray diffraction. Brakhausen Effects utilizes the magnetic properties of ferromagnetic materials such as ferritic and perlitic steels and provides a practical tool for surface streets evaluation. X-ray streets analysis is based on the measurement of lattice strains in different directions of specimen The results obtained by two techniques are compared, avowing a good agreement
ELASTIC-PLASTIC AND RESIDUAL STRESS ANALYSIS OF AN ALUMINUM DISC UNDER INTERNAL PRESSURES

Directory of Open Access Journals (Sweden)

Numan Behlül BEKTAŞ

2004-02-01

Full Text Available This paper deals with elastic-plastic stress analysis of a thin aluminum disc under internal pressures. An analytical solution is performed for satisfying elastic-plastic stress-strain relations and boundary conditions for small plastic deformations. The Von-Mises Criterion is used as a yield criterion, and elastic perfectly plastic material is assumed. Elastic-plastic and residual stress distributions are obtained from inner radius to outer radius, and they are presented in tables and figures. All radial stress components, ?r, are compressive, and they are highest at the inner radius. All tangential stress components, ??, are tensile, and they are highest where the plastic deformation begins. Magnitude of the tangential residual stresses is higher than those the radial residual stresses.

Analyses of edge effects on residual stresses in film strip/substrate systems

International Nuclear Information System (INIS)

Hsueh, Chun-Hway

2000-01-01

The residual stress distribution in a thin-film strip overlaid on a substrate is influenced by the edges of the strip. An analytical model is developed to derive a closed-form solution for the stress distribution along the film width. Because the film is much thinner than the substrate, the stress variation through the film thickness is ignored; however, the stress variation through the substrate thickness is considered in the analysis. Compared to the existing analytical models, the present model is more rigorous and the analytical results agree better with both finite element results and experimental measurements. (c) 2000 American Institute of Physics
Influence of phase transformations on the asymptotic residual stress distribution arising near a sharp V-notch tip

International Nuclear Information System (INIS)

Ferro, P

2012-01-01

In this work, the residual stress distribution induced by the solidification and cooling of a fusion zone in the vicinity of a sharp V-notch tip is investigated. The intensity of the residual asymptotic stress fields, quantified by the notch stress intensity factors, was studied for two different V-notch specimen geometries under generalized plane-strain conditions. In order to analyze the influence of phase transformations on the obtained results, simulations with and without the effects of phase transformation were carried out on ASTM SA 516 steel plates. Thanks to the possibilities of numerical modelling, additional analyses were performed without taking into account the transformation plasticity phenomenon. It was found that phase transformation effects (both volume change and transformation plasticity) have a great influence on the intensity and sign of the asymptotic stress fields at the sharp V-notch tips. This result is believed to be very important for the correct numerical determination (and future applications) of notch stress intensity factors resulting from asymptotic residual stress distributions induced by transient thermal loads. The analyses were performed with the finite element code SYSWELD. (paper)
Finite element analysis and measurement for residual stress of dissimilar metal weld in pressurizer safety nozzle mockup

International Nuclear Information System (INIS)

Lee, Kyoung Soo; Kim, W.; Lee, Jeong Geun; Park, Chi Yong; Yang, Jun Seok; Kim, Tae Ryong; Park, Jai Hak

2009-01-01

Finite element (FE) analysis and experiment for weld residual stress (WRS) in the pressurizer safety nozzle mockup is described in various processes and results. Foremost of which is the dissimilar simulation metal welding (DMW) between carbon steel and austenitic stainless steel. Thermal and structural analyses were compared with actual residual stress, and actual measurements of. Magnitude and distribution of WRS in the nozzle mockup were assessed. Two measurement methods were used: hole-drilling method (HDM) with strain gauge for residual stress on the surface of the mockup, and block removal and splitting layer (BRSL) method for through-thickness. FE analysis and measurement data showed good agreement. In conclusion, the characteristics of weld residual stress of DMW could be well understood and the simplified FE analysis was verified as acceptable for estimating WRS
Finite element analysis and measurement for residual stress of dissimilar metal weld in pressurizer safety nozzle mockup

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyoung Soo; Kim, W.; Lee, Jeong Geun; Park, Chi Yong; Yang, Jun Seok; Kim, Tae Ryong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); Park, Jai Hak [Chungbuk University, Cheongju (Korea, Republic of)

2009-11-15

Finite element (FE) analysis and experiment for weld residual stress (WRS) in the pressurizer safety nozzle mockup is described in various processes and results. Foremost of which is the dissimilar simulation metal welding (DMW) between carbon steel and austenitic stainless steel. Thermal and structural analyses were compared with actual residual stress, and actual measurements of. Magnitude and distribution of WRS in the nozzle mockup were assessed. Two measurement methods were used: hole-drilling method (HDM) with strain gauge for residual stress on the surface of the mockup, and block removal and splitting layer (BRSL) method for through-thickness. FE analysis and measurement data showed good agreement. In conclusion, the characteristics of weld residual stress of DMW could be well understood and the simplified FE analysis was verified as acceptable for estimating WRS
Residual stress evaluation and curvature behavior of aluminum 7050 peen forming processed; Avaliacao da tensao residual em aluminio 7050 conformado pelo processo peen forming

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Rene Ramos de

2011-07-01

Shot peening is a superficial cold work process used to increase the fatigue life evaluated by residual stress measurements. The peen forming process is a variant of the shot peening process, where a curvature in the plate is obtained by the compression of the grains near to the surface. In this paper, the influence of the parameters such as: pressure of shot, ball shot size and thickness of aluminum 7050 samples with respect to residual stress profile and resulting arc height was studied. The evaluation of the residual stress profile was obtained by sin{sup 2} {psi} method. The results show that the formation of the curvature arc height is proportional to the shot peening pressure, of spheres size and inversely proportional to the thickness of the sample, and that stress concentration factor is larger for samples shot peened with small balls. On final of this paper presents an additional study on micro strain and average crystallite size, which can evaluate the profile of the samples after blasting. (author)
FEM Analysis and Measurement of Residual Stress by Neutron Diffraction on the Dissimilar Overlay Weld Pipe

International Nuclear Information System (INIS)

Kim, Kang Soo; Lee, Ho Jin; Woo, Wan Chuck; Seong, Baek Seok; Byeon, Jin Gwi; Park, Kwang Soo; Jung, In Chul

2010-01-01

Much research has been done to estimate the residual stress on a dissimilar metal weld. There are many methods to estimate the weld residual stress and FEM (Finite Element Method) is generally used due to the advantage of the parametric study. And the X-ray method and a Hole Drilling technique for an experimental method are also usually used. The aim of this paper is to develop the appropriate FEM model to estimate the residual stresses of the dissimilar overlay weld pipe. For this, firstly, the specimen of the dissimilar overlay weld pipe was manufactured. The SA 508 Gr3 nozzle, the SA 182 safe end and SA376 pipe were welded by the Alloy 182. And the overlay weld by the Alloy 52M was performed. The residual stress of this specimen was measured by using the Neutron Diffraction device in the HANARO (High-flux Advanced Neutron Application ReactOr) research reactor, KAERI (Korea Atomic Energy Research Institute). Secondly, FEM Model on the dissimilar overlay weld pipe was made and analyzed by the ABAQUS Code (ABAQUS, 2004). Thermal analysis and stress analysis were performed, and the residual stress was calculated. Thirdly, the results of the FEM analysis were compared with those of the experimental methods
The Effect of Stochastically Varying Creep Parameters on Residual Stresses in Ceramic Matrix Composites

Science.gov (United States)

Pineda, Evan J.; Mital, Subodh K.; Bednarcyk, Brett A.; Arnold, Steven M.

2015-01-01

Constituent properties, along with volume fraction, have a first order effect on the microscale fields within a composite material and influence the macroscopic response. Therefore, there is a need to assess the significance of stochastic variation in the constituent properties of composites at the higher scales. The effect of variability in the parameters controlling the time-dependent behavior, in a unidirectional SCS-6 SiC fiber-reinforced RBSN matrix composite lamina, on the residual stresses induced during processing is investigated numerically. The generalized method of cells micromechanics theory is utilized to model the ceramic matrix composite lamina using a repeating unit cell. The primary creep phases of the constituents are approximated using a Norton-Bailey, steady state, power law creep model. The effect of residual stresses on the proportional limit stress and strain to failure of the composite is demonstrated. Monte Carlo simulations were conducted using a normal distribution for the power law parameters and the resulting residual stress distributions were predicted.
Influence of thermal residual stress on behaviour of metal matrix composites reinforced with particles

Science.gov (United States)

Guzmán, R. E.; Hernández Arroyo, E.

2016-02-01

The properties of a metallic matrix composites materials (MMC's) reinforced with particles can be affected by different events occurring within the material in a manufacturing process. The existence of residual stresses resulting from the manufacturing process of these materials (MMC's) can markedly differentiate the curves obtained in tensile tests obtained from compression tests. One of the themes developed in this work is the influence of residual stresses on the mechanical behaviour of these materials. The objective of this research work presented is numerically estimate the thermal residual stresses using a unit cell model for the Mg ZC71 alloy reinforced with SiC particles with volume fraction of 12% (hot-forging technology). The MMC's microstructure is represented as a three dimensional prismatic cube-shaped with a cylindrical reinforcing particle located in the centre of the prism. These cell models are widely used in predicting stress/strain behaviour of MMC's materials, in this analysis the uniaxial stress/strain response of the composite can be obtained through the calculation using the commercial finite-element code.
Determination of the plastic deformation and residual stress tensor distribution using surface and bulk intrinsic magnetic properties

International Nuclear Information System (INIS)

Hristoforou, E.; Svec, P. Sr.

2015-01-01

We have developed an unique method to provide the stress calibration curve in steels: performing flaw-less welding in the under examination steel, we obtained to determine the level of the local plastic deformation and the residual stress tensors. These properties where measured using both the X-ray and the neutron diffraction techniques, concerning their surface and bulk stresses type II (intra-grain stresses) respectively, as well as the stress tensor type III by using the electron diffraction technique. Measuring the distribution of these residual stresses along the length of a welded sample or structure, resulted in determining the local stresses from the compressive to tensile yield point. Local measurement of the intrinsic surface and bulk magnetic property tensors allowed for the un-hysteretic correlation. The dependence of these local magnetic tensors with the above mentioned local stress tensors, resulting in a unique and almost un-hysteretic stress calibration curve of each grade of steel. This calibration integrated the steel's mechanical and thermal history, as well as the phase transformations and the presence of precipitations occurring during the welding process.Additionally to that, preliminary results in different grade of steels reveal the existence of a universal law concerning the dependence of magnetic and magnetostrictive properties of steels on their plastic deformation and residual stress state, as they have been accumulated due to their mechanical and thermal fatigue and history. This universality is based on the unique dependence of the intrinsic magnetic properties of steels normalized with a certain magnetoelastic factor, upon the plastic deformation or residual stress state, which, in terms, is normalized with their yield point of stress. (authors)
Residual stress control and design of next-generation ultra-hard gear steels

Science.gov (United States)

Qian, Yana

In high power density transmission systems, Ni-Co secondary hardening steels have shown great potential for next-generation gear applications due to their excellent strength, toughness and superior fatigue performance. Study of residual stress generation and evolution in Ferrium C61 and C67 gear steels revealed that shot peening and laser peening processes effectively produce desired beneficial residual stress in the steels for enhanced fatigue performance. Surface residual stress levels of -1.4GPa and -1.5GPa were achieved in shot peened C61 and laser peened C67, respectively, without introducing large surface roughness or defects. Higher compressive residual stress is expected in C67 according to a demonstrated correlation between attainable residual stress and material hardness. Due to the lack of appropriate shot media, dual laser peening is proposed for future peening optimization in C67. A novel non-destructive synchrotron radiation technique was implemented and applied for the first time for residual stress distribution analysis in gear steels with large composition and property gradients. Observed substantial residual stress redistribution and material microstructure change during the rolling contact fatigue screening test with extremely high 5.4GPa load indicates the unsuitability of the test as a fatigue life predictor. To exploit benefits of higher case hardness and associated residual stress, a new material and process (CryoForm70) aiming at 70Rc surface hardness was designed utilizing the systems approach based on thermodynamics and secondary hardening mechanisms. The composition design was first validated by the excellent agreement between experimental and theoretical core martensite start temperature in the prototype. A novel cryogenic deformation process was concurrently designed to increase the case martensite volume fraction from 76% to 92% for enhanced strengthening efficiency and surface hardness. High temperature vacuum carburizing was
The Effect of Creep on the Residual Stresses Generated During Silicon Sheet Growth

Science.gov (United States)

Hutchinson, J. W.; Lambropoulos, J. C.

1984-01-01

The modeling of stresses generated during the growth of thin silicon sheets at high speeds is an important part of the EFG technique since the experimental measurement of the stresses is difficult and prohibitive. The residual stresses which arise in such a growth process lead to serious problems which make thin Si ribbons unsuitable for fabrication. The constitutive behavior is unrealistic because at high temperature (close to the melting point) Si exhibits considerable creep which significantly relaxes the residual stresses. The effect of creep on the residual stresses generated during the growth of Si sheets at high speeds was addressed and the basic qualitative effect of creep are reported.
Modelling Of Residual Stresses Induced By High Speed Milling Process

International Nuclear Information System (INIS)

Desmaison, Olivier; Mocellin, Katia; Jardin, Nicolas

2011-01-01

Maintenance processes used in heavy industries often include high speed milling operations. The reliability of the post-process material state has to be studied. Numerical simulation appears to be a very interesting way to supply an efficient residual stresses (RS) distribution prediction.Because the adiabatic shear band and the serrated chip shaping are features of the austenitic stainless steel high speed machining, a 2D high speed orthogonal cutting model is briefly presented. This finite element model, developed on Forge registered software, is based on data taken from Outeiro and al.'s paper [1]. A new behaviour law fully coupling Johnson-Cook's constitutive law and Latham and Cockcroft's damage model is detailed in this paper. It ensures results that fit those found in literature.Then, the numerical tools used on the 2D model are integrated to a 3D high speed milling model. Residual stresses distribution is analysed, on the surface and into the depth of the material. Various revolutions and passes of the two teeth hemispheric mill on the workpiece are simulated. Thus the sensitivity of the residual stresses generation to the cutting conditions can be discussed. In order to validate the 3D model, a comparison of the cutting forces measured by EDF R and D to those given by numerical simulations is achieved.
A strategy for accommodating residual stresses in the assessment of repair weldments based upon measurement of near surface stresses

International Nuclear Information System (INIS)

Mcdonald, E.J.; Hallam, K.R.; Flewitt, P.E.J.

2005-01-01

On many occasions repairs are undertaken to ferritic steel weldments on plant either during construction or to remove service induced defects. These repaired weldments are subsequently put into service with or without a post-weld heat treatment. In either case, but particularly for the latter, there is a need to accommodate the associated residual stresses in structural integrity assessments such as those based upon the R6 failure avoidance procedure. Although in some circumstances the residual macro-stresses developed within weldments of components and structures can be calculated this is not so readily achieved in the case of residual stresses introduced by repair welds. There is a range of physical and mechanical techniques available to undertake the measurement of macro-residual stresses. Of these X-ray diffraction has the advantage that it is essentially non-destructive and offers the potential for evaluating stresses, which exist in the near surface layer. Although for many structural integrity assessments both the magnitude and distribution of residual stresses have to be accommodated it is not practical to make destructive measurements on weld repaired components and structures to establish the through section distribution of stresses. An approach is to derive a description of the appropriate macro-stresses by a combination of measurement and calculation on trial ferritic steel repair weldments. Surface measurements on the plant can then be made to establish the relationship between the repaired component or structure and the trial weld and thereby improve confidence in predicted stresses and their distribution from the near-surface measured values. Hence X-ray diffraction measurements at the near-surface of the plant weldment can be used to underwrite the quality of the repair by confirming the magnitude and distribution of residual stresses used for the integrity assessment to demonstrate continued safe operation
Analysis of residual stress state in sheet metal parts processed by single point incremental forming

Science.gov (United States)

Maaß, F.; Gies, S.; Dobecki, M.; Brömmelhoff, K.; Tekkaya, A. E.; Reimers, W.

2018-05-01

The mechanical properties of formed metal components are highly affected by the prevailing residual stress state. A selective induction of residual compressive stresses in the component, can improve the product properties such as the fatigue strength. By means of single point incremental forming (SPIF), the residual stress state can be influenced by adjusting the process parameters during the manufacturing process. To achieve a fundamental understanding of the residual stress formation caused by the SPIF process, a valid numerical process model is essential. Within the scope of this paper the significance of kinematic hardening effects on the determined residual stress state is presented based on numerical simulations. The effect of the unclamping step after the manufacturing process is also analyzed. An average deviation of the residual stress amplitudes in the clamped and unclamped condition of 18 % reveals, that the unclamping step needs to be considered to reach a high numerical prediction quality.
A generic approach for a linear elastic fracture mechanics analysis of components containing residual stress

International Nuclear Information System (INIS)

Lee, Hyeong Y.; Nikbin, Kamran M.; O'Dowd, Noel P.

2005-01-01

A review of through thickness transverse residual stress distribution measurements in a number of components, manufactured from a range of steels, has been carried out. Residual stresses introduced by welding and mechanical deformation have been considered. The geometries consisted of welded T-plate joints, pipe butt joints, tube-on-plate joints, tubular Y-joints and tubular T-joints as well as cold bent tubes and repair welds. In addition, the collected data cover a range of engineering steels including ferritic, austenitic, C-Mn and Cr-Mo steels. The methods used to measure the residual stresses also varied. These included neutron diffraction, X-ray diffraction and deep hole drilling techniques. Measured residual stress data, normalised by their respective yield stress have shown an inverse linear correlation versus the normalised depth of the region containing the residual stress (up to 0.5 of the component thickness). A simplified generic residual stress profile based on a linear fit to the data is proposed for the case of a transverse residual tensile stress field. Whereas the profiles in assessment procedures are case specific the proposed linear profile can be varied to produce a combination of membrane and bending stress distributions to give lower or higher levels of conservatism on stress intensity factors, depending on the amount of case specific data available or the degree of safety required
Residual stresses and fatigue in a duplex stainless steel

International Nuclear Information System (INIS)

Johansson, Johan

1999-01-01

Duplex stainless steels, consisting of approximately equal amounts of austenite and ferrite, often combine the best features of austenitic and ferritic stainless steels. They generally have good mechanical properties, including high strength and ductility, and the corrosion resistance is often better than conventional austenitic grades. This has lead to a growing use of duplex stainless steels as a material in mechanically loaded constructions. However, detailed knowledge regarding its mechanical properties and deformation mechanisms are still lacking. In this thesis special emphasis has been placed on the residual stresses and their influence on mechanical behaviour of duplex stainless steels. Due to the difference in coefficient of thermal expansion between the two phases, tensile microstresses are found in the austenitic phase and balancing compressive microstresses in the ferritic phase. The first part of this thesis is a literature survey, which will give an introduction to duplex stainless steels and review the fatigue properties of duplex stainless steels and the influence of residual stresses in two-phase material. The second part concerns the evolution of the residual stress state during uniaxial loading. Initial residual stresses were found to be almost two times higher in the transverse direction compared to the rolling direction. During loading the absolute value of the microstresses increased in the macroscopic elastic regime but started to decrease with increasing load in the macroscopic plastic regime. A significant increase of the microstresses was also found to occur during unloading. Finite element simulations also show stress variation within one phase and a strong influence of both the elastic and plastic anisotropy of the individual phases on the simulated stress state. In the third part, the load sharing between the phases during cyclic loading is studied. X-ray diffraction stress analysis and transmission electron microscopy show that even if
Residual stresses and fatigue in a duplex stainless steel

Energy Technology Data Exchange (ETDEWEB)

Johansson, Johan

1999-05-01

Duplex stainless steels, consisting of approximately equal amounts of austenite and ferrite, often combine the best features of austenitic and ferritic stainless steels. They generally have good mechanical properties, including high strength and ductility, and the corrosion resistance is often better than conventional austenitic grades. This has lead to a growing use of duplex stainless steels as a material in mechanically loaded constructions. However, detailed knowledge regarding its mechanical properties and deformation mechanisms are still lacking. In this thesis special emphasis has been placed on the residual stresses and their influence on mechanical behaviour of duplex stainless steels. Due to the difference in coefficient of thermal expansion between the two phases, tensile microstresses are found in the austenitic phase and balancing compressive microstresses in the ferritic phase. The first part of this thesis is a literature survey, which will give an introduction to duplex stainless steels and review the fatigue properties of duplex stainless steels and the influence of residual stresses in two-phase material. The second part concerns the evolution of the residual stress state during uniaxial loading. Initial residual stresses were found to be almost two times higher in the transverse direction compared to the rolling direction. During loading the absolute value of the microstresses increased in the macroscopic elastic regime but started to decrease with increasing load in the macroscopic plastic regime. A significant increase of the microstresses was also found to occur during unloading. Finite element simulations also show stress variation within one phase and a strong influence of both the elastic and plastic anisotropy of the individual phases on the simulated stress state. In the third part, the load sharing between the phases during cyclic loading is studied. X-ray diffraction stress analysis and transmission electron microscopy show that even if
SPR Characteristics Curve and Distribution of Residual Stress in Self-Piercing Riveted Joints of Steel Sheets

Directory of Open Access Journals (Sweden)

Rezwanul Haque

2017-01-01

Full Text Available Neutron diffraction was used to describe the residual stress distributions in self-piercing riveted (SPR joints. The sheet material displayed a compressive residual stress near the joint, and the stress gradually became tensile in the sheet material far away from the joint. The stress in the rivet leg was lower in the thick joint of the softer steel sheet than in the thin joint of the harder steel sheet. This lower magnitude was attributed to the lower force gradient during the rivet flaring stage of the SPR process curve. This study shows how the residual stress results may be related to the physical occurrences that happened during joining, using the characteristics curve. The study also shows that neutron diffraction technique enabled a crack in the rivet tip to be detected which was not apparent from a cross-section.
Residual stresses analysis in ball end milling of nickel-based superalloy Inconel 718

Energy Technology Data Exchange (ETDEWEB)

Wang, Junteng; Zhang, Dinghua; Wu, Baohai; Luo, Ming [Key Laboratory of Contemporary Design and Integrated Manufacturing Technology, Northwestern Polytechnical University (China)

2017-11-15

Inconel 718 is widely used in the aviation, space, automotive and biomedical industries because of its outstanding properties. Near-surface residual stresses that are induced by ball end milling in Inconel 718 can be crucial for the performance and service time of the machined parts. In this paper, the influences of cutting conditions, including the use of cutting parameters, cutting fluid and spindle angles, on the residual stresses in the ball end milling process of Inconel 718 alloy were investigated experimentally. X-ray diffraction measurements reveal that residual stress distributions are highly influenced by cutting parameters, especially the depth of cut and cutting speed. The milling operation with cooling induces more compressive stresses trend and the magnitude of the residual stresses increases in the tensile direction with the increase of spindle angles. These cutting induced effects were further discussed with respect to thermal- mechanical coupling theory and some observations made by optical microscopy. From this investigation, it is suggested that the machining process parameters are not the smaller the better for the control of residual stresses in the ball end milling process of Inconel 718. (author)
Residual Stress Measurement of SiC tile/Al7075 Hybrid Composites by Neutron Diffraction

Energy Technology Data Exchange (ETDEWEB)

Park, Jong Bok; Lee, Jun Ho; Hong, Soon Hyung; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of); Lee, Sang Bok; Lee, Sang Kwan [Korea Institute of Materials Science, Changwon (Korea, Republic of); Muslihd, M. Rifai [Center for Advanced Materials Science and Technology, Tangerang (India)

2016-05-15

In this research, SiC which has low density, high compressive strength, and high elastic modulus was used to fabricate the armor plate. In addition, Al which has low density and high toughness was used for a metal matrix of the composites. If two materials are combined, the composite can be effective materials for light weight armor applications. However, the existence of a large difference in coefficients of thermal expansion (CTE) between SiC and Al matrix, SiC/Al composites can have residual stresses while cooled in the fabrication process. Previous research reported that residual stresses in the composites or microstructures have an effect on the fatigue life and their mechanical properties. Some researchers reported about the residual stresses in the SiCp/Al metal matrix composites by numerical simulation systems, X-ray diffraction, and destructive methods. In order to analyze the residual stress of SiC/Al composites, the neutron diffraction as the non-destructive method was performed in this research. The 50 vol.% SiC{sub p}/Al7075 composites and SiC tile inserted 50 vol.% SiC{sub p}/Al7075 hybrid composites were measured to analyze the residual stress of Al (111) and SiC (111). Both samples had the tensile residual stresses in the Al (111) and the compressive residual stresses in the SiC (111) due to the difference in CTE.

Grain size influence on residual stresses in alumina/zirconia composites

International Nuclear Information System (INIS)

Sergo, V.; Sbaizero, O.; Pezzotti, G.; Nishida, T.

1998-01-01

The grain size (GS) and volume fraction of alumina have been systematically varied in composites with a zirconia matrix and the corresponding residual stresses have been assessed by means of piezospectroscopy. The compressive stress in alumina depends on the volume fraction and it is well predicted by a stochastic model based on information theory. No dependence with GS has been detected, except at the highest volume content (20% vol. alumina). Conversely the stress distribution is independent from the volume fraction and depends on GS: intermediate values of GS exhibit the wider stress distribution. The tensile stress in zirconia shows no clear correlation with the volume fraction and increases with increasing zirconia GS. This latter behavior has been compared with a model based on diffusion relaxation of stresses. The model reproduces correctly the stress change due to different alumina contents, but it diverges from the experimental data at smaller GSs, overestimating the residual stress. It is suggested that grain boundary sliding may also contribute to the relaxation of stresses
The effect of residual stress relaxation by the vibratory stress relief technique on the textures of grains in AA 6061 aluminum alloy

Energy Technology Data Exchange (ETDEWEB)

Wang, Jia-Siang; Hsieh, Chih-Chun; Lin, Chi-Ming; Chen, Erh-Chiang; Kuo, Che-Wei; Wu, Weite, E-mail: wwu@dragon.nchu.edu.tw

2014-05-01

The textures and crystallographic orientations beneath the treatment area in AA 6061 aluminum alloy after vibratory stress relief (VSR) process were investigated by combining the electron backscatter diffraction analysis of the misoriented low- or high-angle boundaries, the (inverse) pole figures, the line scans and the various grain orientations. The relaxation effect caused by compressive residual stress in the intermediate region is superior to that of tensile residual stress on both sides of the cantilever by means of X-ray diffraction techniques. The residual stress relaxation that occurs due to vibrational stress excitation accompanies the “orientation of banding” disintegration, the decreases in the dislocation density, the strain energy, and the fraction of low-angle boundaries within each type of grain orientation, such as Copper {112} 〈111〉, S {123} 〈634〉, Goss {110} 〈001〉, and Brass {110} 〈112〉, excepting the Cube (or near-Cube) {100} 〈001〉 grain orientation. The maintained invariance in the Cube texture can be attributed to the maximum number of active primary slip systems, resulting in an interaction that results from hindered slip on intersecting families of the planes.
The effect of residual stress relaxation by the vibratory stress relief technique on the textures of grains in AA 6061 aluminum alloy

International Nuclear Information System (INIS)

Wang, Jia-Siang; Hsieh, Chih-Chun; Lin, Chi-Ming; Chen, Erh-Chiang; Kuo, Che-Wei; Wu, Weite

2014-01-01

The textures and crystallographic orientations beneath the treatment area in AA 6061 aluminum alloy after vibratory stress relief (VSR) process were investigated by combining the electron backscatter diffraction analysis of the misoriented low- or high-angle boundaries, the (inverse) pole figures, the line scans and the various grain orientations. The relaxation effect caused by compressive residual stress in the intermediate region is superior to that of tensile residual stress on both sides of the cantilever by means of X-ray diffraction techniques. The residual stress relaxation that occurs due to vibrational stress excitation accompanies the “orientation of banding” disintegration, the decreases in the dislocation density, the strain energy, and the fraction of low-angle boundaries within each type of grain orientation, such as Copper {112} 〈111〉, S {123} 〈634〉, Goss {110} 〈001〉, and Brass {110} 〈112〉, excepting the Cube (or near-Cube) {100} 〈001〉 grain orientation. The maintained invariance in the Cube texture can be attributed to the maximum number of active primary slip systems, resulting in an interaction that results from hindered slip on intersecting families of the planes
Residual Stresses in a NiCrY-Coated Powder Metallurgy Disk Superalloy

Science.gov (United States)

Gabb, Timothy P.; Rogers, Richard B.; Nesbitt, James A.; Puleo, Bernadette J.; Miller, Robert A.; Telesman, Ignacy; Draper, Susan L.; Locci, Ivan E.

2017-01-01

Protective ductile coatings will be necessary to mitigate oxidation and corrosion attack on superalloy disks exposed to increasing operating temperatures in some turbine engine environments. However, such coatings must be resistant to harmful surface cracking during service. The objective of this study was to investigate how residual stresses evolve in such coatings. Cylindrical gage fatigue specimens of powder metallurgy-processed disk superalloy LSHR were coated with a NiCrY coating, shot peened, and then subjected to fatigue in air at room and high temperatures. The effects of shot peening and fatigue cycling on average residual stresses and other aspects of the coating were assessed. Shot peening did induce beneficial compressive residual stresses in the coating and substrate. However, these stresses became more tensile in the coating with subsequent heating and contributed to cracking of the coating in long intervals of cycling at 760 C. Substantial compressive residual stresses remained in the substrate adjacent to the coating, sufficient to suppress fatigue cracking. The coating continued to protect the substrate from hot corrosion pitting, even after fatigue cracks initiated in the coating.
Residual and operating stresses in welded Alloy 600 penetrations

International Nuclear Information System (INIS)

Hunt, E.S.; Gross, D.J.; Pathania, R.

1995-01-01

An elastic-plastic finite element model has been developed for calculating residual and operating stresses in Alloy 600 penetrations which are installed in pressure vessel shells by J-groove welds. The welding process is simulated by multiple passes of heat input with heat transfer into the adjacent parts during welding and cooling. Analysis results are presented for CRDM nozzles, pressurizer instrument nozzles and pressurizer heater sleeves. The effect of several key variables such as nozzle material yield strength, angle of the nozzle relative to the vessel shell, weld size, presence of counterbores, etc. are explored. Results of the modelling are correlated with field and laboratory data. Application of the stress analysis results to PWSCC predictive modeling is discussed. (author). 6 refs, 12 figs, 2 tabs
Effect of Plastic Pre-straining on Residual Stress and Composition Profiles in Low-Temperature Surface-Hardened Austenitic Stainless Steel

DEFF Research Database (Denmark)

Bottoli, Federico; Christiansen, Thomas Lundin; Winther, Grethe

2016-01-01

The present work deals with the evaluation of the residual stress profiles in expanded austenite by applying grazing incidence X-ray diffraction (GI-XRD) combined with successive sublayer removal. Annealed and deformed (εeq=0.5) samples of stable stainless steel EN 1.4369 were nitrided...... or nitrocarburized. The residual stress profiles resulting from the thermochemical low-temperature surface treatment were measured. The results indicate high-residual compressive stresses of several GPa’s in the nitrided region, while lower-compressive stresses are produced in the carburized case. Plastic...... deformation in the steel prior to thermochemical treatment has a hardly measurable influence on the nitrogen-rich zone, while it has a measurable effect on the stresses and depth of the carbon-rich zone....
Effects of organic additives on preferred plane and residual stress of copper electroplated on polyimide

International Nuclear Information System (INIS)

Kim, Jongsoo; Kim, Heesan

2010-01-01

Effects of the preferred plane and the residual stress of an electroplated copper on polyethylene glycol (PEG) and 3-N,N-dimethylaminodithiocarbamoyl-1-propanesulfonic acid (DPS) were studied. Polyimide film coated with sputtered copper was used as a substrate. Preferred plane, residual stress, and impurity level in the electroplated copper were measured by an X-ray diffractometry (XRD), calculated by Stoney's equation, and analyzed with secondary ion mass spectroscopy (SMS), respectively. With increasing the concentration of PEG, the preferred plane changed in the order (1 0 0) and (1 1 0) while with increasing the concentration of DPS, the preferred plane changed in the order (1 1 0), (1 0 0), and (1 1 1). Based on the modified preferred growth model, where the amount of additive adsorbed on a plane is newly assumed to be proportional to its surface energy in vacuum, the predicted preferred planes correspond to the experimental results. The residual stress of the electroplated copper depended on the type of additive as well as its concentration but was independent of the preferred plane. For example, PEG and DPS induced tensile and compressive residual stresses in the electroplated copper, respectively, and their magnitudes increased with their concentrations. The dependency of residual stress on the additives was explained by the incorporated additives into the electroplated copper.
Residual stress analysis in linear friction welded in-service Inconel 718 superalloy via neutron diffraction and contour method approaches

Energy Technology Data Exchange (ETDEWEB)

Smith, M. [University of British Columbia – Okanagan, School of Engineering, 3333 University Way, Kelowna, Canada V1V 1V7 (Canada); Levesque, J.-B. [Institut de recherche d' Hydro-Québec (IREQ), 1800 Lionel-Boulet Blvd., Varennes, Canada J3X 1S1 (Canada); Bichler, L., E-mail: lukas.bichler@ubc.ca [University of British Columbia – Okanagan, School of Engineering, 3333 University Way, Kelowna, Canada V1V 1V7 (Canada); Sediako, D. [Canadian Nuclear Laboratories, Building 459, Station 18, Chalk River, Canada K0J 1J0 (Canada); Gholipour, J.; Wanjara, P. [National Research Council of Canada, Aerospace 5145 Decelles Ave., Montreal, Canada H3T 2B2 (Canada)

2017-04-13

In this study, an analysis of elastic residual stress in Inconel{sup ®} 718 (IN 718) linear friction welds (LFWs) was carried out. In particular, the suitability of LFW for manufacturing and repair of aero engine components was emulated by joining virgin and in-service (extracted from a turbine disk) materials. The evolution in the residual strains and stresses in the heat-affected zone (HAZ), thermomechanically affected zone (TMAZ) and dynamically recrystallized zone (DRX) of the weld was characterized using the neutron diffraction and contour methods. The results provided insight into diverse challenges in quantitative analysis of residual stresses in welded IN 718 using diffraction techniques. Specifically, judicious selection of the beam width, height and stress-free lattice spacing were seen to be crucial to minimize measurement error and increase accuracy. Further, the contour method – a destructive technique relying on capturing the stress relaxation after electrical discharge machining – was used to characterize the residual stress distribution on two-dimensional plane sections of the welds. Both techniques suggested an increasing magnitude of residual stress originating from the base metal that reached a peak at the weld interface. Both methods indicated that the peak magnitude of residual stresses were below the yield stress of IN 718.
Residual Stress Measurement of Coarse Crystal Grain in Aluminium Casting Alloy by Neutron Diffraction

International Nuclear Information System (INIS)

Nishida, Masayuki; Watanabe, Yoshitaka; Hanabusa, Takao

2009-01-01

Full text: Neutron stress measurement can detect strain and stress information in deep region because of large penetration ability of neutron beams. The present paper describes procedure and results in the residual stress measurement of aluminium casting alloy by neutron diffraction. Usually, the aluminium casting alloy includes the large crystal grains. The existence of large crystal grains makes it difficult to estimate the residual stresses in highly accuracy. In this study, the modified three axial method using Hook's equation was employed for neutron stress measurement. These stress measurements were performed under the two kinds of new techniques. One is a rocking curve method to calculate the principal strains in three directions. The peak profiles which appear discretely on rocking curves were translated to principle stresses by the Bragg law and the basic elastic theory. Another is the consideration of measurement positions and the edge effect in the neutron irradiated area (volume gage). The edge effect generates the errors of 2θ-peak position in the neutron stress measurement. In this study, the edge effect was investigated in detail by a small bit of copper single crystal. The copper bit was moved and scanned on three dimensionally within the gage volume. Furthermore, the average strains of symmetrical positions are measure by the sample turning at 180 degrees, because the error distributions of the 2θ-peak position followed to positions inside the gage volume. Form these results of this study, the residual stresses in aluminium casting alloy which includes the large crystal grains were possible to estimate by neutron stress measurement with the rocking curve method and the correction of the edge effect. (author)
Residual stresses in a composite steel tube measured by neutron diffraction

International Nuclear Information System (INIS)

Taran, Yu.V.; Balagurov, A.M.; Zlokazov, V.B.; Schreiber, J.; Stuhr, U.; Kockelmann, H.

2006-01-01

The triaxial residual stresses in a composite tube from an austenitic stainless steel with a welded ferritic steel cladding were measured by the time-of-flight neutron diffraction method on the POLDI instrument at the PSI SINQ facility. The POLDI results are compared to the results obtained by the destructive turning out method and theoretical predictions of calculations by the finite element method. Only for the tangential component of the stress tensor the semiquantitative agreement of all used methods was observed. There is a clear discrepancy between the results of the different methods in the axial component. For the radial component all methods reveal quite small stresses, however, with some distinct differences in their distributions
Fatigue behaviour of 304L steel welded structures: influence of residual stresses and surface mechanical finishing

International Nuclear Information System (INIS)

Magnier-Monin, L.

2007-12-01

This study focuses on the influence of residual stresses and surface mechanical finishing on lifetime of stainless steel 304L welded structures. Residual stresses are determined on specific specimens of three types: base-metal, as-welded and ground-welded specimens. Each type is submitted to fatigue tests in order to assess the influence of these parameters on the lifetime, and to determine their evolution. The experiments show that an important surface stress concentration is located in the weld root of as-welded structures, which has a negative effect on the fatigue life. The grinding operation generates high-level surface residual stresses but the lifetime is higher thanks to the reduction of the notch effect. The fatigue test results are compared to the nuclear industry best-fit S-N curves. This enables the determination of correction factors related to fatigue test results of polished specimens, and to assess the lifetime of structures. (author)
Analytic examination of mechanism for compressive residual stress introduction with low plastic strain using peening

International Nuclear Information System (INIS)

Ishibashi, Ryo; Hato, Hisamitsu; Miyazaki, Katsumasa; Yoshikubo, Fujio

2016-01-01

Our goal for this study was to understand the cause of the differences in surface properties between surfaces processed using water jet peening (WJP) and shot peening (SP) and to examine the compressive residual stress introduction process with low plastic strain using SP. The dynamic behaviors of stress and strain in surfaces during these processes were analyzed through elasto-plastic calculations using a finite-element method program, and the calculated results were compared with measured results obtained through experiments. Media impacting a surface results in a difference in the hardness and microstructure of the processed surface. During SP, a shot deforms the surface locally with stress concentration in the early stages of the impact, while shock waves deform the surface evenly throughout the wave passage across the surface during WJP. A shot with a larger diameter creates a larger impact area on the surface during shot impact. Thus, SP with a large-diameter shot suppresses the stress concentration under the same kinetic energy condition. As the shot diameter increases, the equivalent plastic strain decreases. On the other hand, the shot is subject to size restriction since the calculated results indicate the compressive residual stress at the surface decreased and occasionally became almost zero as the shot diameter increased. Thus, compressive residual stress introduction with low plastic strain by using SP is considered achievable by using shots with a large diameter and choosing the appropriate peening conditions. (author)
Residual stress change by thermal annealing in amorphous Sm-Fe-B thin films

International Nuclear Information System (INIS)

Na, S.M.; Suh, S.J.; Kim, H.J.; Lim, S.H.

2002-01-01

The change in the residual stress and its effect on mechanical bending and magnetic properties of sputtered amorphous Sm-Fe-B thin films are investigated as a function of annealing temperature. Two stress components of intrinsic compressive stress and tensile stress due to the difference of the thermal expansion coefficients between the substrate and thin film are used to explain the stress state in as-deposited thin films, and the annealing temperature dependence of residual stress, mechanical bending and magnetic properties
Thermal residual stresses in amorphous thermoplastic polymers

Science.gov (United States)

Grassia, Luigi; D'Amore, Alberto

2010-06-01

An attempt to calculate the internal stresses in a cylindrically shaped polycarbonate (LEXAN-GE) component, subjected to an arbitrary cooling rate, will be described. The differential volume relaxation arising as a result of the different thermal history suffered by each body point was considered as the primary source of stresses build up [1-3]. A numerical routine was developed accounting for the simultaneous stress and structural relaxation processes and implemented within an Ansys® environment. The volume relaxation kinetics was modeled by coupling the KAHR (Kovacs, Aklonis, Hutchinson, Ramos) phenomenological theory [4] with the linear viscoelastic theory [5-7]. The numerical algorithm translates the specific volume theoretical predictions at each body point as applied non-mechanical loads acting on the component. The viscoelastic functions were obtained from two simple experimental data, namely the linear viscoelastic response in shear and the PVT (pressure volume temperature) behavior. The dimensionless bulk compliance was extracted from PVT data since it coincides with the memory function appearing in the KAHR phenomenological theory [7]. It is showed that the residual stress scales linearly with the logarithm of the Biot's number.
Residual stress measurement by x-ray under the consideration of its penetration depth

International Nuclear Information System (INIS)

Doi, Osamu; Ukai, Takayoshi

1983-01-01

The authors derived the fundamental relations between the measured stress by X-ray and the residual stress distribution from the consideration of the contribution of internal stress in definite subsurface layer of metal to X-ray diffraction and proposed the exact formulas and their applications of residual stress measurements by successive thin layer removal in a plate, a hollow cylinder and a hollow sphere. (author)
Investigation of residual stress in laser welding between carbon steel AISI 1010 and stainless AISI 304

International Nuclear Information System (INIS)

Mirim, Denilson de Camargo

2011-01-01

The dissimilar materials union has the residual stress formation as one of the most critical problems, which occurs mainly because these materials have both different thermal expansion coefficients and thermal conductivities. In this study, it was investigated the laser welding technique between steels, AISI 1010 and AISI 304. The materials were joined by butt autogenous welding with a continuous Nd:YAG laser. The main objective was to identify the welding parameters influence by the residual stresses analysis in the heat affected zone (HAZ). It was executed a factorial design with three-factor at two levels with a replica, which were varied power, welding speed and focal position of the laser beam. Residual stress measurements by the diffraction of X-rays were performed on the sample surface, to study their variation as a function of the parameters investigated. The blind hole method was also used to evaluate the residual stress along the samples depth, up to depth of 1mm. Besides residual stress measurement, weld seams were evaluated by optical and scanned electron microscopy, which were aimed to determine the weld geometry and changes in the microstructure. It was also made Vickers hardness measurements to evaluate the extent of HAZ. To evaluate the mechanical properties of the union were performed tensile and fatigue test. The MINITAB 15 software was used to analyze the residual stresses obtained by the blind hole method at different depths of the HAZ. It was also used statistical regression based on both the influences different and the combination of this input factors, in the residual stress of union. The results indicate that the models can satisfactorily predict the responses and provide users a guide to better define the welding parameters. (author)
Effect of shot peening treatment in the behavior of residual stress in duplex stainless steel during medium cycle fatigue

International Nuclear Information System (INIS)

Pedrosa, Peter D.S.; Rebello, Joao Marcos A.; Fonseca, Maria P. Cindra

2010-01-01

The lifetime of duplex stainless steel parts experiencing cyclic fatigue is directly influenced by the residual stresses present in the ferrite and austenite phases. The motivation for this work was to analyze the behaviour of the residual stresses fields introduced by shot peening treatment in both phases, in the sample surface as in the subsurface layers, in low fatigue cycles, using the X-rays diffraction technique. The results shows that the compressive residual stresses introduced by the shot peening treatment in both phases improved fatigue life of the material. However, the cyclical loads produce partial or total relief in these residual stresses fields. It was verified that the shot peening process induced the formation of microcracks only in the ferrite phase. The largest variations in the total compressive residual stresses fields also occurred in this phase. The samples surfaces were analyzed by scanning electron microscopy. (author)
A countermeasure for external stress corrosion cracking in piping components by means of residual stress improvement on the outer surface

International Nuclear Information System (INIS)

Tanaka, Yasuhiro; Umemoto, Tadahiro

1988-01-01

Many techniques have been proposed as countermeasures for the External Stress Corrosion Cracking (ESCC) on austenitic stainless steel piping caused by sea salt particles. However, not one seems perfect. The method proposed here is an expansion of IHSI (Induction Heating Stress Improvement) which has been successfully implemented in many nuclear power plants as a remedy for Intergranular Stress Corrossion Cracking. The proposed method named EIHSI (External IHSI) can make the residual stress compressive on the outer surface of the piping components. In order to confirm the effectiveness of EIHSI, one series of tests were conducted on a weld joint between the pipe flange and the straight pipe. The measured residual stresses and also the results of the cracking test revealed that EIHSI is a superior method to suppress the ESCC. The outline of EIHSI and the verification tests are presented in this paper. (author)
Experimental Analysis of Residual Stresses in Samples of Austenitic Stainless Steel Welded on Martensitic Stainless Steel Used for Kaplan Blades Repairs

Directory of Open Access Journals (Sweden)

Vasile Cojocaru

2011-01-01

Full Text Available Residual stresses occur in materials as a result of mechanical processes: welding, machining, grinding etc. If residual stresses reach high values they can accelerate the occurrence of cracks and erosion of material. An experimental research was made in order to study the occurrence of residual stresses in the repaired areas of hydraulic turbine components damaged by cavitation erosion. An austenitic stainless steel was welded in various layer thicknesses on a martensitic stainless steel base. The residual stresses were determined using the hole drilling strain gage method.
Weld residual stresses near the bimetallic interface in clad RPV steel: A comparison between deep-hole drilling and neutron diffraction data

Energy Technology Data Exchange (ETDEWEB)

James, M.N., E-mail: mjames@plymouth.ac.uk [School of Marine Science and Engineering, University of Plymouth, Drake Circus, Plymouth (United Kingdom); Department of Mechanical Engineering, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Newby, M.; Doubell, P. [Eskom Holdings SOC Ltd, Lower Germiston Road, Rosherville, Johannesburg (South Africa); Hattingh, D.G. [Department of Mechanical Engineering, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Serasli, K.; Smith, D.J. [Department of Mechanical Engineering, University of Bristol, Queen' s Building, University Walk, Bristol (United Kingdom)

2014-07-01

Highlights: • Identification of residual stress trends across bimetallic interface in stainless clad RPV. • Comparison between deep hole drilling (DHD – stress components in two directions) and neutron diffraction (ND – stress components in three directions). • Results indicate that both techniques can assess the trends in residual stress across the interface. • Neutron diffraction gives more detailed information on transient residual stress peaks. - Abstract: The inner surface of ferritic steel reactor pressure vessels (RPV) is clad with strip welded austenitic stainless steel primarily to increase the long-term corrosion resistance of the ferritic vessel. The strip welding process used in the cladding operation induces significant residual stresses in the clad layer and in the RPV steel substrate, arising both from the thermal cycle and from the very different thermal and mechanical properties of the austenitic clad layer and the ferritic RPV steel. This work measures residual stresses using the deep hole drilling (DHD) and neutron diffraction (ND) techniques and compares residual stress data obtained by the two methods in a stainless clad coupon of A533B Class 2 steel. The results give confidence that both techniques are capable of assessing the trends in residual stresses, and their magnitudes. Significant differences are that the ND data shows greater values of the tensile stress peaks (∼100 MPa) than the DHD data but has a higher systematic error associated with it. The stress peaks are sharper with the ND technique and also differ in spatial position by around 1 mm compared with the DHD technique.

Weld residual stresses near the bimetallic interface in clad RPV steel: A comparison between deep-hole drilling and neutron diffraction data

International Nuclear Information System (INIS)

James, M.N.; Newby, M.; Doubell, P.; Hattingh, D.G.; Serasli, K.; Smith, D.J.

2014-01-01

Highlights: • Identification of residual stress trends across bimetallic interface in stainless clad RPV. • Comparison between deep hole drilling (DHD – stress components in two directions) and neutron diffraction (ND – stress components in three directions). • Results indicate that both techniques can assess the trends in residual stress across the interface. • Neutron diffraction gives more detailed information on transient residual stress peaks. - Abstract: The inner surface of ferritic steel reactor pressure vessels (RPV) is clad with strip welded austenitic stainless steel primarily to increase the long-term corrosion resistance of the ferritic vessel. The strip welding process used in the cladding operation induces significant residual stresses in the clad layer and in the RPV steel substrate, arising both from the thermal cycle and from the very different thermal and mechanical properties of the austenitic clad layer and the ferritic RPV steel. This work measures residual stresses using the deep hole drilling (DHD) and neutron diffraction (ND) techniques and compares residual stress data obtained by the two methods in a stainless clad coupon of A533B Class 2 steel. The results give confidence that both techniques are capable of assessing the trends in residual stresses, and their magnitudes. Significant differences are that the ND data shows greater values of the tensile stress peaks (∼100 MPa) than the DHD data but has a higher systematic error associated with it. The stress peaks are sharper with the ND technique and also differ in spatial position by around 1 mm compared with the DHD technique
Depth-resolved X-ray residual stress analysis in PVD (Ti, Cr) N hard coatings

CERN Document Server

Genzel, C

2003-01-01

Physical vapour deposition (PVD) of thin hard coatings on TiN basis is usually performed at rather low temperatures (T sub D < 500 C) far from thermal equilibrium, which leads to high intrinsic residual stresses in the growing film. In contrast to the extrinsic thermal residual stresses which can easily be estimated from the difference of the coefficients of thermal expansion between the substrate and the coating, a theoretical prediction of the intrinsic residual stresses is difficult, because their amount as well as their distribution within the film depend in a very complex way on the deposition kinetics. By the example of strongly fibre-textured PVD (Ti, Cr)N coatings which have been prepared under defined variation of the deposition parameters in order to adjust the residual stress distribution within the coatings, the paper compares different X-ray diffraction techniques with respect to their applicability for detecting residual stresses which are non-uniform over the coating thickness. (orig.)
An analytical model to predict and minimize the residual stress of laser cladding process

Science.gov (United States)

Tamanna, N.; Crouch, R.; Kabir, I. R.; Naher, S.

2018-02-01

Laser cladding is one of the advanced thermal techniques used to repair or modify the surface properties of high-value components such as tools, military and aerospace parts. Unfortunately, tensile residual stresses generate in the thermally treated area of this process. This work focuses on to investigate the key factors for the formation of tensile residual stress and how to minimize it in the clad when using dissimilar substrate and clad materials. To predict the tensile residual stress, a one-dimensional analytical model has been adopted. Four cladding materials (Al2O3, TiC, TiO2, ZrO2) on the H13 tool steel substrate and a range of preheating temperatures of the substrate, from 300 to 1200 K, have been investigated. Thermal strain and Young's modulus are found to be the key factors of formation of tensile residual stresses. Additionally, it is found that using a preheating temperature of the substrate immediately before laser cladding showed the reduction of residual stress.
Assessment of residual stress of 7050-T7452 aluminum alloy forging using the contour method

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zheng [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Yang, Yinfei, E-mail: yyfgoat@nuaa.edu.cn [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Li, Liang [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Chen, Bo; Tian, Hui [Xi’an Aircraft Industrial (Group) Co. Ltd., Xi’an 710000 (China)

2015-09-17

The cold-compression stress relief process has been used to reduce the quench-induced stresses in high-strength aerospace aluminum alloy forgings. However, this method does not completely relieve the stress. Longitudinal residual stresses in 7050-T7452 aluminum alloy forging were measured with contour method. The measuring procedure of the contour method including specimen cutting under clamps with a wire electrical discharge machine, contour measurement of the cut surface with a laser scanner, careful data processing and elastic finite element analysis was introduced in detail. In addition, multiple cuts were used to map cross sectional stress at different cut surfaces. Finally, the longitudinal residual stress throughout the cut plane was mapped, and through thickness longitudinal stress profiles were also analyzed. Investigated results suggest that spatial variation of stress distribution can be attributed to the non-uniform plastic deformation of the cold-compression stress relief process. The overall reduction of peak stress magnitudes is approximately 43–79%.
Assessment of residual stress of 7050-T7452 aluminum alloy forging using the contour method

International Nuclear Information System (INIS)

Zhang, Zheng; Yang, Yinfei; Li, Liang; Chen, Bo; Tian, Hui

2015-01-01

The cold-compression stress relief process has been used to reduce the quench-induced stresses in high-strength aerospace aluminum alloy forgings. However, this method does not completely relieve the stress. Longitudinal residual stresses in 7050-T7452 aluminum alloy forging were measured with contour method. The measuring procedure of the contour method including specimen cutting under clamps with a wire electrical discharge machine, contour measurement of the cut surface with a laser scanner, careful data processing and elastic finite element analysis was introduced in detail. In addition, multiple cuts were used to map cross sectional stress at different cut surfaces. Finally, the longitudinal residual stress throughout the cut plane was mapped, and through thickness longitudinal stress profiles were also analyzed. Investigated results suggest that spatial variation of stress distribution can be attributed to the non-uniform plastic deformation of the cold-compression stress relief process. The overall reduction of peak stress magnitudes is approximately 43–79%
Residual stress evaluation and fatigue life prediction in the welded joint by X-ray diffraction

International Nuclear Information System (INIS)

Yoo, Keun Bong; Kim, Jae Hoon

2009-01-01

In the fossil power plant, the reliability of the components which consist of the many welded parts depends on the quality of welding. The residual stress is occurred by the heat flux of high temperature during weld process. This decreases the mechanical properties as the strength of fatigue and fracture or occurs the stress corrosion cracking and fatigue fracture. The residual stress of the welded part in the recently constructed power plants has been the cause of a variety of accidents. The objective of this study is measurement of the residual stress by X-ray diffraction method and to estimate the feasibility of this application for fatigue life assessment of the high-temperature pipeline. The materials used for the study is P92 steel for the use of high temperature pipe on super critical condition. The test results were analyzed by the distributed characteristics of residual stresses and the Full Width at Half Maximum intensity (FWHM) in x-ray diffraction intensity curve. Also, X-ray diffraction tests using specimens simulated low cycle fatigue damage were performed in order to analyze fatigue properties when fatigue damage conditions become various stages. As a result of X-ray diffraction tests for specimens simulated fatigue damages, we conformed that the ratio of the FWHM due to fatigue damage has linear relationship with fatigue life ratio algebraically. From this relationships, it was suggested that direct expectation of the life consumption rate was feasible.
The adhesion strength and residual stress of colloidal-sol gel derived β-Tricalcium-Phosphate/Fluoridated-Hydroxyapatite biphasic coatings

International Nuclear Information System (INIS)

Cheng Kui; Zhang, Sam; Weng Wenjian; Khor, Khiam Aik; Miao Shundong; Wang Yongsheng

2008-01-01

β-tricalcium phosphate (β-TCP) powders are embedded in a fluoridated hydroxyapatite (FHA) matrix to form β-TCP-FHA composites via colloidal-sol gel method. This composite layer is deposited on top of a FHA layer to form a β-TCP-FHA/FHA biphasic coating. The effect of the nanosized powder on the residual stress is characterized through the X-ray diffraction peak shift. The powder incorporation increases the residual stress, while a large amount of β-TCP (Ca powder /Ca sol ratio is higher than 1/2) results in less gel shrinkage that partially compensates the mismatch of thermal expansion coefficient and thus the residual stress. Despite the elevated residual stress as more powders are embedded, the coating adhesion strength remains virtually constant: around 430 mN-500 mN in scanning scratch test
Study on residual stresses in ultrasonic torsional vibration assisted micro-milling

Science.gov (United States)

Lu, Zesheng; Hu, Haijun; Sun, Yazhou; Sun, Qing

2010-10-01

It is well known that machining induced residual stresses can seriously affect the dimensional accuracy, corrosion and wear resistance, etc., and further influence the longevity and reliability of Micro-Optical Components (MOC). In Ultrasonic Torsional Vibration Assisted Micro-milling (UTVAM), cutting parameters, vibration parameters, mill cutter parameters, the status of wear length of tool flank are the main factors which affect residual stresses. A 2D model of UTVAM was established with FE analysis software ABAQUS. Johnson-Cook's flow stress model and shear failure principle are used as the workpiece material model and failure principle, while friction between tool and workpiece uses modified Coulomb's law whose sliding friction area is combined with sticking friction. By means of FEA, the influence rules of cutting parameters, vibration parameters, mill cutter parameters, the status of wear length of tool flank on residual stresses are obtained, which provides a basis for choosing optimal process parameters and improving the longevity and reliability of MOC.
Near-surface residual stresses and microstructural changes after turning of a nickel-based superalloy

Energy Technology Data Exchange (ETDEWEB)

Schlauer, Christian

2003-07-01

Nickel-based superalloys are precipitation hardened alloys with complex compositions. They are used in aircraft engines and land-based gas turbines in load bearing structural components that are exposed to high temperatures. Failure mechanisms in this environment are high and low cycle fatigue, creep, and corrosion. During manufacturing, residual stresses are often introduced into the material due to inhomogeneous plastic deformations, both intentionally and unintentionally. One such manufacturing process is metal cutting, which introduces residual stresses in the surface layer. The stress state in the near-surface zone of components is of special interest as the surface often experiences peak loads and cracks have their starting point there. In this thesis, near-surface residual stress distributions and microstructural changes are studied in the nickel-based superalloy Inconel 718 for two different turning operations, face grooving and facing. Process variables are in both cases cutting speed and feed that have been varied between (10 and 1200) m/min and (0.01 and 0.5) mm, respectively. The first turning technique face grooving, which gives cutting conditions similar to orthogonal cutting, showed a clear dependency of the residual stresses on the cutting speed. The tensile stress at the surface, the maximum compressive stress below the surface, and the thickness of the affected layer increase with increasing cutting speed. The tensile stresses are constrained to a thin surface layer and compressive residual stresses below the surface dominate the depth profile of the residual stresses. Only at low cutting speed, residual stresses were largely avoided. The second turning technique facing confirmed the dependency of the residual stresses on the cutting speed and revealed a similar dependency on the feed. Microstructural investigations of near-surface cross-sections by means of transmission electron microscopy showed a zone where the grains had undergone plastic
3-D characteristics of the residual stress in the plate weld between SA508 and stainless steel 316L

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyoung Soo; Kim, Tae Ryong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); Park, Jai Hak [Chungbuk National Univ., Cheongju (Korea, Republic of); Kim, Man Won [Global New-clear Engineering and Consulting, Daejeon (Korea, Republic of); Cho, Seon Yeong [Korea Laboratory Engineering System Company, Cheonan (Korea, Republic of)

2008-07-01

This study is performed to check the three dimensional characteristics of residual stress in the dissimilar metal weld. Although two dimensional analysis has been widely used for the assessment of weld residual stress, it has limitations to understand the stress distribution of the third direction. 3-D analysis was done to understand residual stress distribution of the welded plate. A simple butt-welded plate was considered to show the stress variation on all direction. A mock-up plate weldment was fabricated with SA-508 and F316L, which are widely used in nuclear power plants. The analysis results were validated with the measured values in the mock-up.
Role of symmetry-breaking induced by Er × B shear flows on developing residual stresses and intrinsic rotation in the TEXTOR tokamak

International Nuclear Information System (INIS)

Xu, Y.; Shesterikov, I.; Berte, M.; Dumortier, P.; Van Schoor, M.; Vergote, M.; Hidalgo, C.; Krämer-Flecken, A.; Koslowski, R.

2013-01-01

Direct measurements of residual stress (force) have been executed at the edge of the TEXTOR tokamak using multitip Langmuir and Mach probes, together with counter-current NBI torque to balance the existing toroidal rotation. Substantial residual stress and force have been observed at the plasma boundary, confirming the existence of a finite residual stress as possible mechanisms to drive the intrinsic toroidal rotation. In low-density discharges, the residual stress displays a quasi-linear dependence on the local pressure gradient, consistent with theoretical predictions. At high-density shots the residual stress and torque are strongly suppressed. The results show close correlation between the residual stress and the E r × B flow shear rate, suggesting a minimum threshold of the E × B flow shear required for the k ∥ symmetry breaking. These findings provide the first experimental evidence of the role of E r × B sheared flows in the development of residual stresses and intrinsic rotation. (letter)
Recovery and residual stress of SMA wires and applications for concrete structures

International Nuclear Information System (INIS)

Choi, Eunsoo; Cho, Sung-Chul; Park, Taehyo; Hu, Jong Wan; Chung, Young-Soo

2010-01-01

In general, NiTi shape memory alloys are used for applications in civil structures. NiTi SMAs show good superelasticity and shape memory effect properties. However, for application of the shape memory effect, it is desirable for SMAs to show a wide temperature hysteresis, especially for civil structures which are exposed to severe environmental conditions. NiTiNb SMAs, in general, show a wider temperature hysteresis than NiTi SMAs and are more applicable for civil structures. This study examines the temperature hysteresis of NiTiNb and NiTi SMAs, and their recovery and residual stress are investigated. In addition, the tensile behaviors of SMA wires under residual stress are evaluated. This study explains the possible applications for concrete structures with the shape memory effect and illustrates two experimental results of concrete cylinders and reinforced concrete columns. For both tests, SMA wires of NiTiNb and NiTi are used to confine concrete using residual stress. The SMA wire jackets on the concrete cylinders increase the peak strength and the ductility compared to the plain concrete cylinders. In addition, the SMA wire jackets on reinforced concrete columns increase the ductility greatly without flexural strength degradation
Residual stress measurement in veneering ceramic by hole-drilling.

Science.gov (United States)

Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

2011-05-01

Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. The hole-drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5-1.0mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. The hole drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Residual stress measurement by X-ray diffraction with the Gaussian curve method and its automation

International Nuclear Information System (INIS)

Kurita, M.

1987-01-01

X-ray technique with the Gaussian curve method and its automation are described for rapid and nondestructive measurement of residual stress. A simplified equation for measuring the stress by the Gaussian curve method is derived because in its previous form this method required laborious calculation. The residual stress can be measured in a few minutes, depending on materials, using an automated X-ray stress analyzer with a microcomputer which was developed in the laboratory. The residual stress distribution of a partially induction hardened and tempered (at 280 0 C) steel bar was measured with the Gaussian curve method. A sharp residual tensile stress peak of 182 MPa appeared right outside the hardened region at which fatigue failure is liable to occur
Effect of preemptive weld overlay sequence on residual stress distribution for dissimilar metal weld of Kori nuclear power plant pressurizer

Energy Technology Data Exchange (ETDEWEB)

Bae, Hong Yeol; Song, Tae Kwang; Chun, Yun Bae; Oh, Chang Young; Kim, Yun Jae [Korea Univ., Seoul (Korea, Republic of); Lee, Kyoung Soo; Park, Chi Yong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

2008-07-01

Weld overlay is one of the residual stress mitigation method which arrest crack. An overlay weld sued in this manner is termed a Preemptive Weld OverLay(PWOL). PWOL was good for distribution of residual stress of Dissimilar Metal Weld(DMW) by previous research. Because range of overlay welding is wide relatively, residual stress distribution on PWR is affected by welding sequence. In order to examine the effect of welding sequence, PWOL was applied to a specific DMW of KORI nuclear power plant by finite element analysis method. As a result, the welding direction that from nozzle to pipe is better good for residual stress distribution on PWR.
Effect of preemptive weld overlay sequence on residual stress distribution for dissimilar metal weld of Kori nuclear power plant pressurizer

International Nuclear Information System (INIS)

Bae, Hong Yeol; Song, Tae Kwang; Chun, Yun Bae; Oh, Chang Young; Kim, Yun Jae; Lee, Kyoung Soo; Park, Chi Yong

2008-01-01

Weld overlay is one of the residual stress mitigation method which arrest crack. An overlay weld sued in this manner is termed a Preemptive Weld OverLay(PWOL). PWOL was good for distribution of residual stress of Dissimilar Metal Weld(DMW) by previous research. Because range of overlay welding is wide relatively, residual stress distribution on PWR is affected by welding sequence. In order to examine the effect of welding sequence, PWOL was applied to a specific DMW of KORI nuclear power plant by finite element analysis method. As a result, the welding direction that from nozzle to pipe is better good for residual stress distribution on PWR
X-ray fractography by using synchrotron radiation source. Residual stress distribution just beneath fatigue fracture surface

International Nuclear Information System (INIS)

Akita, Koichi; Yoshioka, Yasuo; Suzuki, Hiroshi; Sasaki, Toshihiko

2000-01-01

The residual stress distributions just beneath the fatigue fracture surface were measured using synchrotron radiation with three different wavelengths, i.e., three different penetration depths. The residual stress distributions were estimated from three kinds of diffraction data by the following process. First, a temporary residual stress distribution in the depth direction is assumed. Theoretical 2θ-sin 2 ψ diagrams for each wavelength, where each has a different penetration depth, are calculated by the cosψ method developed by one of the authors. The sum total of the differences between the theoretical and experimental values of the diffraction angle in 2θ-sin 2 ψ diagrams is calculated. This total value is minimized by changing the assumed stress distribution by the quasi-Newton optimization method. Finally, optimized 2θ-sin 2 ψ diagrams for each penetration depth and detailed stress distribution are determined. The true surface residual stress is obtained from this stress distribution. No effect of load ratio R (= P min /P max ) on the residual stresses of the fatigue fracture surfaces in low-carbon steels was observed when the sin 2 ψ method was used for stress measurement. However, the residual stresses became higher with increasing R when these were measured by the proposed method. On the basis of this, the stress intensity factor range, ΔK, can be estimated from the residual stress on the fatigue fracture surface. (author)
Variation behavior of residual stress distribution by manufacturing processes in welded pipes of austenitic stainless steel

International Nuclear Information System (INIS)

Ihara, Ryohei; Hashimoto, Tadafumi; Mochizuki, Masahito

2012-01-01

Stress corrosion cracking (SCC) has been observed near heat affected zone (HAZ) of primary loop recirculation pipes made of low-carbon austenitic stainless steel type 316L in the nuclear power plants. For the non-sensitization material, residual stress is the important factor of SCC, and it is generated by machining and welding. In the actual plants, welding is conducted after machining as manufacturing processes of welded pipes. It could be considered that residual stress generated by machining is varied by welding as a posterior process. This paper presents residual stress variation due to manufacturing processes of pipes using X-ray diffraction method. Residual stress distribution due to welding after machining had a local maximum stress in HAZ. Moreover, this value was higher than residual stress generated by welding or machining. Vickers hardness also had a local maximum hardness in HAZ. In order to clarify hardness variation, crystal orientation analysis with EBSD method was performed. Recovery and recrystallization were occurred by welding heat near the weld metal. These lead hardness decrease. The local maximum region showed no microstructure evolution. In this region, machined layer was remained. Therefore, the local maximum hardness was generated at machined layer. The local maximum stress was caused by the superposition effect of residual stress distributions due to machining and welding. Moreover, these local maximum residual stress and hardness are exceeded critical value of SCC initiation. In order to clarify the effect of residual stress on SCC initiation, evaluation including manufacturing processes is important. (author)
Weld repair practices without post weld heat treatment for ferritic alloys and their consequences on residual stresses: A review

International Nuclear Information System (INIS)

Aloraier, A.; Al-Mazrouee, A.; Price, J.W.H.; Shehata, T.

2010-01-01

The use of the half-bead, temper bead welding (TBW), and cold repair techniques is proving to reduce the cost of repairs and extend the life of aged components in power plants, petrochemical and hydrocarbon processing industries. It has been a significant area of interest for more than twenty years. A critical factor in this context is residual stress. The presence of residual stresses can lead to cracking which ultimately results in structural failure. This paper reviews the half-bead, TBW, and cold repair technique practices and their consequences on residual stresses within the nuclear, power, refinery and petrochemical industries and some of the contributions made by our group of researchers in this area. This paper reviews recent work by the Monash University group. We report our work on TBW residual stresses when measured using neutron diffraction which shows very little reduction in residual stresses over normally completed welds. The use of automatic FCAW has been explored in our group and is reported.
A Simplified Model for the Effect of Weld-Induced Residual Stresses on the Axial Ultimate Strength of Stiffened Plates

Science.gov (United States)

Chen, Bai-Qiao; Guedes Soares, C.

2018-03-01

The present work investigates the compressive axial ultimate strength of fillet-welded steel-plated ship structures subjected to uniaxial compression, in which the residual stresses in the welded plates are calculated by a thermo-elasto-plastic finite element analysis that is used to fit an idealized model of residual stress distribution. The numerical results of ultimate strength based on the simplified model of residual stress show good agreement with those of various methods including the International Association of Classification Societies (IACS) Common Structural Rules (CSR), leading to the conclusion that the simplified model can be effectively used to represent the distribution of residual stresses in steel-plated structures in a wide range of engineering applications. It is concluded that the widths of the tension zones in the welded plates have a quasi-linear behavior with respect to the plate slenderness. The effect of residual stress on the axial strength of the stiffened plate is analyzed and discussed.

Residual stresses and critical diameter in vitreous matrix materials

International Nuclear Information System (INIS)

Mastelaro, Valmor R.; Zanotto, Edgar D.

1995-01-01

The present study was undertaken to test the validity of existing models for: i) the residual internal stresses which arise due to thermal and elastic mismatch in duplex systems, and ii) the critical particle diameter for spontaneous cracking. Partially crystallized 1,07 Na 2 O-2 Ca O-3 Si O 2 - 6% P 2 O 5 glasses were studied. The experimental residual stress was in excellent agreement with the calculated value, however, the critical particle diameter, estimated by an energy balance approach, was more than ten times smaller than the experimental value. This discrepancy indicates that the energy model is not applicable in this case. (author)
Reduction of Residual Stresses in Sapphire Cover Glass Induced by Mechanical Polishing and Laser Chamfering Through Etching

Directory of Open Access Journals (Sweden)

Shih-Jeh Wu

2016-10-01

Full Text Available Sapphire is a hard and anti-scratch material commonly used as cover glass of mobile devices such as watches and mobile phones. A mechanical polishing using diamond slurry is usually necessary to create mirror surface. Additional chamfering at the edge is sometimes needed by mechanical grinding. These processes induce residual stresses and the mechanical strength of the sapphire work piece is impaired. In this study wet etching by phosphate acid process is applied to relief the induced stress in a 1” diameter sapphire cover glass. The sapphire is polished before the edge is chamfered by a picosecond laser. Residual stresses are measured by laser curvature method at different stages of machining. The results show that the wet etching process effectively relief the stress and the laser machining does not incur serious residual stress.
Residual stress and mechanical properties of SiC ceramic by heat treatment

International Nuclear Information System (INIS)

Yoon, H.K.; Kim, D.H.; Shin, B.C.

2007-01-01

Full text of publication follows: Silicon carbide is a compound of relatively low density, high hardness, elevated thermal stability and good thermal conductivity, resulting in good thermal shock resistance. Because of these properties, SiC materials are widely used as abrasives and refractories. In this study, SiC single and poly crystals was grown by the sublimation method using the SiC seed crystal and SiC powder as the source material. Mechanical properties of SiC single and poly crystals are carried out by using the nano-indentation method and small punch test after the heat treatment. As a result, mechanical properties of SiC poly crystal had over double than single. And SiC single and poly crystals were occurred residual stress, but residual stress was shown relaxant properties by the effect of heat treatment. (authors)
Residual stress state in pipe cut ring specimens for fracture toughness testing

Energy Technology Data Exchange (ETDEWEB)

Damjanovic, Darko [J.J. Strossmayer Univ. of Osijek, Slavonski Brod (Croatia). Mechanical Engineering Faculty; Kozak, Drazan [Zagreb Univ. (Croatia). Dept. for Mechanical Design; Marsoner, Stefan [Materials Center, Leoben (Austria).; Gubeljak, Nenad [Maribor Univ. (Slovenia). Chair of Mechanics

2017-07-01

Thin-walled pipes are not suitable for measuring fracture toughness parameters of vital importance because longitudinal crack failure is the most common failure mode in pipes. This is due to the impossibility to manufacture standard specimens for measuring fracture toughness, such as SENB or CT specimens, from the thin wall of the pipe. Previous works noticed this problem, but until now, a good and convenient solution has not been found or developed. To overcome this problem, very good alternative solution was proposed, the so-called pipe ring notched bend specimen (PRNB) [1-5]. Until now, only the idealized geometry PRNB specimen is analyzed, i. e., a specimen which is not cut out from an actual pipe but produced from steel plate. Based on that, residual stresses are neglected along with the imperfections in geometry (elliptical and eccentricity). The aim of this research is to estimate the residual stress state(s) in real pipes used in the boiler industry produced by hot rolling technique. These types of pipes are delivered only in normalized condition, but not stress relieved. Therefore, there are residual stresses present due to the manufacturing technique, but also due to uneven cooling after the production process. Within this paper, residual stresses are estimated by three methods: the incremental hole drilling method (IHMD), X-ray diffraction (XRD) and the splitting method (SM). Knowing the residual stress state in the ring specimen, it is possible to assess their impact on fracture toughness measured on the corresponding PRNB specimen(s).
Residual stress state in pipe cut ring specimens for fracture toughness testing

International Nuclear Information System (INIS)

Damjanovic, Darko; Kozak, Drazan; Marsoner, Stefan; Gubeljak, Nenad

2017-01-01

Thin-walled pipes are not suitable for measuring fracture toughness parameters of vital importance because longitudinal crack failure is the most common failure mode in pipes. This is due to the impossibility to manufacture standard specimens for measuring fracture toughness, such as SENB or CT specimens, from the thin wall of the pipe. Previous works noticed this problem, but until now, a good and convenient solution has not been found or developed. To overcome this problem, very good alternative solution was proposed, the so-called pipe ring notched bend specimen (PRNB) [1-5]. Until now, only the idealized geometry PRNB specimen is analyzed, i. e., a specimen which is not cut out from an actual pipe but produced from steel plate. Based on that, residual stresses are neglected along with the imperfections in geometry (elliptical and eccentricity). The aim of this research is to estimate the residual stress state(s) in real pipes used in the boiler industry produced by hot rolling technique. These types of pipes are delivered only in normalized condition, but not stress relieved. Therefore, there are residual stresses present due to the manufacturing technique, but also due to uneven cooling after the production process. Within this paper, residual stresses are estimated by three methods: the incremental hole drilling method (IHMD), X-ray diffraction (XRD) and the splitting method (SM). Knowing the residual stress state in the ring specimen, it is possible to assess their impact on fracture toughness measured on the corresponding PRNB specimen(s).
Tensile Residual Stress Mitigation Using Low Temperature Phase Transformation Filler Wire in Welded Armor Plates

Energy Technology Data Exchange (ETDEWEB)

Feng, Zhili [ORNL; Bunn, Jeffrey R [ORNL; Tzelepis, Demetrios A [ORNL; Payzant, E Andrew [ORNL; Yu, Xinghua [ORNL

2016-01-01

Hydrogen induced cracking (HIC) has been a persistent issue in welding of high-strength steels. Mitigating residual stresses is one of the most efficient ways to control HIC. The current study develops a proactive in-process weld residual stress mitigation technique, which manipulates the thermal expansion and contraction sequence in the weldments during welding process. When the steel weld is cooled after welding, martensitic transformation will occur at a temperature below 400 C. Volume expansion in the weld due to the martensitic transformation will reduce tensile stresses in the weld and heat affected zone and in some cases produce compressive residual stresses in the weld. Based on this concept, a customized filler wire which undergoes a martensitic phase transformation during cooling was developed. The new filler wire shows significant improvement in terms of reducing the tendency of HIC in high strength steels. Bulk residual stress mapping using neutron diffraction revealed reduced tensile and compressive residual stresses in the welds made by the new filler wire.
Reliability assessment of underground pipelines under the combined effect of active corrosion and residual stress

International Nuclear Information System (INIS)

Amirat, A.; Mohamed-Chateauneuf, A.; Chaoui, K.

2006-01-01

Lifetime management of underground pipelines is mandatory for safe hydrocarbon transmission and distribution systems. Reliability analysis is recognized as a powerful decision-making tool for risk-based design and maintenance. Both the residual stresses generated during the manufacturing process and in-service corrosion reduce the ability to resist internal and external loading. In this study, the residual stress distribution in large diameter pipes has been characterized experimentally in order to be coupled with the corrosion model. During the pipe lifetime, residual stress relaxation occurs due to the loss of pipe thickness as material layers are consumed by corrosion. The reliability-based assessment of residual stress effects is applied to underground pipelines under a roadway, with and without active corrosion. It has been found that the residual stress greatly increases the failure probability, especially in the early stage of the pipe lifetime
In-situ observation of dislocation and analysis of residual stresses by FEM/DDM modeling in water cavitation peening of pure titanium

International Nuclear Information System (INIS)

Ju, D Y; Han, B

2015-01-01

In this paper, in order to approach this problem, specimens of pure titanium were treated with WCP, and the subsequent changes in microstructure, residual stress, and surface morphologies were investigated as a function of WCP duration. The influence of water cavitation peening (WCP) treatment on the microstructure of pure titanium was investigated. A novel combined finite element and dislocation density method (FEM/DDM), proposed for predicting macro and micro residual stresses induced on the material subsurface treated with water cavitation peening, is also presented. A bilinear elastic-plastic finite element method was conducted to predict macro-residual stresses and a dislocation density method was conducted to predict micro-residual stresses. These approaches made possible the prediction of the magnitude and depth of residual stress fields in pure titanium. The effect of applied impact pressures on the residual stresses was also presented. The results of the FEM/DDM modeling were in good agreement with those of the experimental measurements. (paper)
Residual thermal stresses in a solid sphere cast from a thermosetting material

Science.gov (United States)

Levitsky, M.; Shaffer, B. W.

1975-01-01

Expressions are developed for the residual thermal stresses in a solid sphere cast from a chemically hardening thermosetting material in a rigid spherical mold. The description of the heat generation rate and temperature variation is derived from a first-order chemical reaction. Solidification is described by the continuous transformation of the material from an inviscid liquidlike state into an elastic solid, with intermediate properties determined by the degree of chemical reaction. Residual stress components are obtained as functions of the parameters of the hardening process and the properties of the hardening material. Variation of the residual stresses with a nondimensionalized reaction rate parameter and the relative compressibility of the hardened material is discussed in detail.
Research on fatigue behavior and residual stress of large-scale cruciform welding joint with groove

International Nuclear Information System (INIS)

Zhao, Xiaohui; Liu, Yu; Liu, Yong; Gao, Yuan

2014-01-01

Highlights: • The fatigue behavior of the large-scale cruciform welding joint with groove was studied. • The longitudinal residual stress of the large-scale cruciform welding joint was tested by contour method. • The fatigue fracture mechanism of the large-scale cruciform welding joint with groove was analyzed. - Abstract: Fatigue fracture behavior of the 30 mm thick Q460C-Z steel cruciform welded joint with groove was investigated. The fatigue test results indicated that fatigue strength of 30 mm thick Q460C-Z steel cruciform welded joint with groove can reach fatigue level of 80 MPa (FAT80). Fatigue crack source of the failure specimen initiated from weld toe. Meanwhile, the microcrack was also found in the fusion zones of the fatigue failure specimen, which was caused by weld quality and weld metal integrity resulting from the multi-pass welds. Two-dimensional map of the longitudinal residual stress of 30 mm thick Q460C-Z steel cruciform welded joint with groove was obtained by using the contour method. The stress nephogram of Two-dimensional map indicated that longitudinal residual stress in the welding center is the largest
Effect of preemptive weld overlay on residual stress mitigation for dissimilar metal weld of nuclear power plant pressurizer

International Nuclear Information System (INIS)

Song, Tae Kwang; Bae, Hong Yeol; Chun, Yun Bae; Oh, Chang Young; Kim, Yun Jae; Lee, Kyoung Soo; Park, Chi Yong

2008-01-01

Weld overlay is one of the residual stress mitigation methods which arrest crack initiation and crack growth. Therefore weld overlay can be applied to the region where cracking is likely to be. An overlay weld used in this manner is termed a Preemptive Weld OverLay(PWOL). In Pressurized Water Reactor(PWR) dissimilar metal weld is susceptible region for Primary Water Stress Corrosion Cracking(PWSCC). In order to examine the effect of PWOL on residual stress mitigation, PWOL was applied to a specific dissimilar metal weld of Kori nuclear power plant by finite element analysis method. As a result, strong compressive residual stress was made in PWSCC susceptible region and PWOL was proved effective preemptive repair method for weldment
Effect of preemptive weld overlay on residual stress mitigation for dissimilar metal weld of nuclear power plant pressurizer

Energy Technology Data Exchange (ETDEWEB)

Song, Tae Kwang; Bae, Hong Yeol; Chun, Yun Bae; Oh, Chang Young; Kim, Yun Jae [Korea University, Seoul (Korea, Republic of); Lee, Kyoung Soo; Park, Chi Yong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

2008-10-15

Weld overlay is one of the residual stress mitigation methods which arrest crack initiation and crack growth. Therefore weld overlay can be applied to the region where cracking is likely to be. An overlay weld used in this manner is termed a Preemptive Weld OverLay(PWOL). In Pressurized Water Reactor(PWR) dissimilar metal weld is susceptible region for Primary Water Stress Corrosion Cracking(PWSCC). In order to examine the effect of PWOL on residual stress mitigation, PWOL was applied to a specific dissimilar metal weld of Kori nuclear power plant by finite element analysis method. As a result, strong compressive residual stress was made in PWSCC susceptible region and PWOL was proved effective preemptive repair method for weldment.
Evaluation of residual stress on pipe welded joints using laser interferometry

Energy Technology Data Exchange (ETDEWEB)

Chang, Ho Seob; Na, Man Gyun; Kim, Koung Suk [Chosun University, Gwangju (Korea, Republic of)

2014-02-15

Residual stresses that occur during the welding process, are the main cause of failure and defects in welded structures. This paper, presents the use of an electronic processing laser speckle interferometer to measure the residual stress of a welded pipe for a nuclear power plant. A tensile testing machine was used to evaluate a welded pipe that failed in compression. The inform plane deformation and modulus of elasticity of the base metal and welds were measured using an interferometer. Varying the load on the welded pipe had a larger effect on the deformation of the base metal the other properties of the base metal and welds. The elastic moduli of the base metal and weld of the welded pipe were 202.46 and 212.14 GPa, respectively, the residual stress was measured to be 6.29 MPa.
Experimental determination of residual stress by neutron diffraction in a boiling water reactor core shroud

International Nuclear Information System (INIS)

Payzant, A.; Spooner, S.; Zhu, Xiaojing; Hubbard, C.R.

1996-01-01

Residual strains in a 51 mm (2-inch) thick 304L stainless steel plate have been measured by neutron diffraction and interpreted in terms of residual stress. The plate, measuring (300 mm) in area, was removed from a 6m (20-ft.) diameter unirradiated boiling water reactor core shroud, and included a multiple-pass horizontal weld which joined two of the cylindrical shells which comprise the core shroud. Residual stress mapping was undertaken in the heat affected zone, concentrating on the outside half of the plate thickness. Variations in residual stresses with location appeared consistent with trends expected from finite element calculations, considering that a large fraction of the residual hoop stress was released upon removal of the plate from the core shroud cylinder
Residual stress in ion implanted titanium nitride studied by parallel beam glancing incidence x-ray diffraction

International Nuclear Information System (INIS)

Geist, D.E.; Perry, A.J.; Treglio, J.R.; Valvoda, V.; Rafaja, D.

1995-01-01

Ion implantation is known to increase the lifetime of cutting tools. Current theories are the increase in lifetime is caused by an increase in the residual stress, or by work hardening of the surface associated with the implantation. In this work the effect of ion implantation on the residual stress in titanium nitride coatings made by the standard industrial methods of chemical and physical vapor deposition (CVD and PVD) is studied. It is found in the as-received condition (unimplanted), the residual stress levels are near zero for CVD materials and highly compressive, of the order of 6 GPa, for PVD materials. Ion implantation has no effect on the residual stress in the coatings made by CVD. Nitrogen does increase the compressive residual stress by some 10% in the near surface regions of PVD coatings, while nickel-titanium dual metal ion implantation does not have any effect. It appears that the lifetime increase is not associated with residual stress effects
Improvement in accuracy of the measurements of residual stresses due to circumferential welds in thin-walled pipe using Rayleigh wave method

International Nuclear Information System (INIS)

Akhshik, Siamak; Moharrami, Rasool

2009-01-01

To achieve an acceptable safety in many industrial applications such as nuclear power plants and power generation, it is extremely important to gain an understanding of the magnitudes and distributions of the residual stresses in a pipe formed by joining two sections with a girth butt weld. Most of the methods for high-accuracy measurement of residual stress are destructive. These destructive measurement methods cannot be applied to engineering systems and structures during actual operation. In this paper, we present a method based on the measurement of ultrasonic Rayleigh wave velocity variations versus the stress state for nondestructive evaluation of residual stress in dissimilar pipe welded joint. We show some residual stress profile obtained by this method. These are then compared with other profiles determined using a semi-destructive technique (hole-drilling) that makes it possible to check our results. According to the results, we also present a new method for adjusting the ultrasonic measurements to improve the agreement with the results obtained from other techniques.
Surface mechanical property and residual stress of peened nickel-aluminum bronze determined by in-situ X-ray diffraction

Science.gov (United States)

Wang, Chengxi; Jiang, Chuanhai; Zhao, Yuantao; Chen, Ming; Ji, Vincent

2017-10-01

As one of the most important surface strengthening method, shot peening is widely used to improve the fatigue and stress corrosion crack resistance of components by introducing the refined microstructure and compressive residual stress in the surface layer. However, the mechanical properties of this thin layer are different from the base metal and are difficult to be characterized by conventional techniques. In this work, a micro uniaxial tensile tester equipped with in-situ X-ray stress analyzer was employed to make it achievable on a nickel-aluminum bronze with shot peening treatment. According to the equivalent stress-strain relationship based on Von Mises stress criterion, the Young's modulus and yield strength of the peened layer were calculated. The results showed that the Young's modulus was the same as the bulk material, and the yield strength corresponding to the permanent plastic strain of 0.2% was increased by 21% after SP. But the fractographic analysis showed that the fracture feature of the surface layer was likely to transform from the dimple to the cleavage, indicating the improved strength might be attained at the expense of ductility. The monotonic and cyclic loading were also performed via the same combined set-up. In addition, the specific relaxation behavior of compressive residual stress was quantified by linear logarithm relationship between residual stress and cycle numbers. It was found that the compressive residual stress mainly relaxed in the first few cycles, and then reached steady state with further cycles. The relaxation rate and the stable value were chiefly depended on the stress amplitude and number of cycles. The retained residual stress kept in compressive under all given applied stress levels, suggesting that the shot peening could introduce a more stable surface layer of compressive residual stress other than the elevated strength of nickel-aluminum bronze alloy.
Through-Thickness Residual Stress Profiles in Austenitic Stainless Steel Welds: A Combined Experimental and Prediction Study

Science.gov (United States)

Mathew, J.; Moat, R. J.; Paddea, S.; Francis, J. A.; Fitzpatrick, M. E.; Bouchard, P. J.

2017-12-01

Economic and safe management of nuclear plant components relies on accurate prediction of welding-induced residual stresses. In this study, the distribution of residual stress through the thickness of austenitic stainless steel welds has been measured using neutron diffraction and the contour method. The measured data are used to validate residual stress profiles predicted by an artificial neural network approach (ANN) as a function of welding heat input and geometry. Maximum tensile stresses with magnitude close to the yield strength of the material were observed near the weld cap in both axial and hoop direction of the welds. Significant scatter of more than 200 MPa was found within the residual stress measurements at the weld center line and are associated with the geometry and welding conditions of individual weld passes. The ANN prediction is developed in an attempt to effectively quantify this phenomenon of `innate scatter' and to learn the non-linear patterns in the weld residual stress profiles. Furthermore, the efficacy of the ANN method for defining through-thickness residual stress profiles in welds for application in structural integrity assessments is evaluated.
X-ray diffraction and measurement of residual stresses

International Nuclear Information System (INIS)

Maeder, G.; Lebrun, J.L.; Corcaud, L.

1977-01-01

X-ray diffraction technique is a non destructive method for measuring the residual stresses in mechanical parts. This method, called sin 2 PSI method is investigated. It is applied to the measurement of elastic constants in different directions of crystals of Zr alloy (Zircaloy 4) and Ti alloy (TA6V). Stresses in TA6V sheets welded by TIG and electron beam processes are also studied [fr
Simulation of Distortion and Residual Stress Development During Heat Treatment of Steel Castings

Energy Technology Data Exchange (ETDEWEB)

Beckermann, Christoph; Carlson, Kent

2011-07-22

Heat treatment and associated processing, such as quenching, are critical during high strength steel casting production. These processes must be managed closely to prevent thermal and residual stresses that may result in distortion, cracking (particularly after machining), re-work, and weld repair. The risk of casting distortion limits aggressive quenching that can be beneficial to the process and yield an improved outcome. As a result of these distortions, adjustments must be made to the casting or pattern design, or tie bars must be added. Straightening castings after heat treatments can be both time-consuming and expensive. Residual stresses may reduce a casting's overall service performance, possibly resulting in catastrophic failure. Stress relieving may help, but expends additional energy in the process. Casting software is very limited in predicting distortions during heat treatment, so corrective measures most often involve a tedious trial-and-error procedure. An extensive review of existing heat treatment residual stress and distortion modeling revealed that it is vital to predict the phase transformations and microstructure of the steel along with the thermal stress development during heat treatment. After reviewing the state-of-the-art in heat treatment residual stress and distortion modeling, an existing commercial code was selected because of its advanced capabilities in predicting phase transformations, the evolving microstructure and related properties along with thermal stress development during heat treatment. However, this software was developed for small parts created from forgings or machined stock, and not for steel castings. Therefore, its predictive capabilities for heat treatment of steel castings were investigated. Available experimental steel casting heat treatment data was determined to be of insufficient detail and breadth, and so new heat treatment experiments were designed and performed, casting and heat treating modified versions

Residual transpiration as a component of salinity stress tolerance mechanism: a case study for barley.

Science.gov (United States)

Hasanuzzaman, Md; Davies, Noel W; Shabala, Lana; Zhou, Meixue; Brodribb, Tim J; Shabala, Sergey

2017-06-19

While most water loss from leaf surfaces occurs via stomata, part of this loss also occurs through the leaf cuticle, even when the stomata are fully closed. This component, termed residual transpiration, dominates during the night and also becomes critical under stress conditions such as drought or salinity. Reducing residual transpiration might therefore be a potentially useful mechanism for improving plant performance when water availability is reduced (e.g. under saline or drought stress conditions). One way of reducing residual transpiration may be via increased accumulation of waxes on the surface of leaf. Residual transpiration and wax constituents may vary with leaf age and position as well as between genotypes. This study used barley genotypes contrasting in salinity stress tolerance to evaluate the contribution of residual transpiration to the overall salt tolerance, and also investigated what role cuticular waxes play in this process. Leaves of three different positions (old, intermediate and young) were used. Our results show that residual transpiration was higher in old leaves than the young flag leaves, correlated negatively with the osmolality, and was positively associated with the osmotic and leaf water potentials. Salt tolerant varieties transpired more water than the sensitive variety under normal growth conditions. Cuticular waxes on barley leaves were dominated by primary alcohols (84.7-86.9%) and also included aldehydes (8.90-10.1%), n-alkanes (1.31-1.77%), benzoate esters (0.44-0.52%), phytol related compounds (0.22-0.53%), fatty acid methyl esters (0.14-0.33%), β-diketones (0.07-0.23%) and alkylresorcinols (1.65-3.58%). A significant negative correlation was found between residual transpiration and total wax content, and residual transpiration correlated significantly with the amount of primary alcohols. Both leaf osmolality and the amount of total cuticular wax are involved in controlling cuticular water loss from barley leaves under well
Type I and type II residual stress in iron meteorites determined by neutron diffraction measurements

Science.gov (United States)

Caporali, Stefano; Pratesi, Giovanni; Kabra, Saurabh; Grazzi, Francesco

2018-04-01

In this work we present a preliminary investigation by means of neutron diffraction experiment to determine the residual stress state in three different iron meteorites (Chinga, Sikhote Alin and Nantan). Because of the very peculiar microstructural characteristic of this class of samples, all the systematic effects related to the measuring procedure - such as crystallite size and composition - were taken into account and a clear differentiation in the statistical distribution of residual stress in coarse and fine grained meteorites were highlighted. Moreover, the residual stress state was statistically analysed in three orthogonal directions finding evidence of the existence of both type I and type II residual stress components. Finally, the application of von Mises approach allowed to determine the distribution of type II stress.
The influence of long-range residual stress on plastic collapse of pressurised pipes with and without flaws

International Nuclear Information System (INIS)

Wu, Gui-Yi; Smith, David J.; Pavier, Martyn J.

2013-01-01

Structural integrity assessments of pressurised pipes include plastic collapse as a potential failure mode. This paper uses analytical and numerical models to explore the effect of the end conditions of the pipe on the collapse pressure. The pipe is open-ended and two bounding conditions are addressed: one where axial loading is applied to the ends of the pipe and the other where a fixed axial displacement is applied. The fixed axial displacement condition represents long-range or fit-up residual stress. It is common practice to treat long-range residual stress in the same way as axial loading, leading to the conclusion that such long-range residual stress reduces the collapse pressure. Pipes in a number of states are considered: pipes with no flaws, pipes with fully circumferential flaws and pipes with part circumferential flaws. The flaws consist of either a crack or a slot on the external surface of the pipe. For the axial load condition, the collapse pressure for a flawed pipe is reduced when higher magnitudes of tensile or compressive axial loads are applied. For the fixed displacement condition however, the magnitude of the displacement may have little or no effect on the collapse pressure. The results of the work indicate that substantially conservative assessments may be made of the collapse pressures of pipes containing flaws, when long-range residual stress is taken to be a form of axial loading. -- Highlights: • The effect of end conditions on the collapse pressure of a pipe has been explored. • Fixed displacement conditions represent long-range residual stress. • Long-range residual stress is commonly thought to contribute to plastic collapse. • We show long-range residual stress has no influence on collapse for flawed pipes. • It is therefore possible to reduce conservatism in structural integrity assessment
Effect of preemptive weld overlay on residual stress of repaired weldment in surge nozzle

Energy Technology Data Exchange (ETDEWEB)

Oh, Chang Young; Song, Tae Kwang; Bae, Hong Yeol; Chun, Yun Bae; Kim, Yun Jae [Korea Univ., Seoul (Korea, Republic of); Lee, Kyoung Soo; Park, Chi Yong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

2008-07-01

In the welding process, weldments usually include repair weld during the manufacturing process. Repair welds is supposed to cause strong tensile residual stress. Moreover weldments, usually made by Alloy 82/182, is susceptible to PWSCC. Therefore, mitigation of welding residual stress in weldments is important for reliable operating. PWOL is one of the methods for mitigation and verified for over twenty years. In this paper, residual stress distribution of repaired weldments and the effect of PWOL on mitigation is examined for surge nozzle.
Residual Stress Induced by Nitriding and Nitrocarburizing

DEFF Research Database (Denmark)

Somers, Marcel A.J.

2005-01-01

The present chapter is devoted to the various mechanisms involved in the buildup and relief of residual stress in nitrided and nitrocarburized cases. The work presented is an overview of model studies on iron and iron-based alloys. Subdivision is made between the compound (or white) layer......, developing at the surfce and consisting of iron-based (carbo)nitrides, and the diffusion zone underneath, consisting of iron and alloying element nitrides dispersed in af ferritic matrix. Microstructural features are related directly to the origins of stress buildup and stres relief....
Residual stress in the first wall coating materials of TiC and TiN for fusion reactor

International Nuclear Information System (INIS)

Qiu Shaoyu

1997-01-01

Residual stresses measurement in the first wall coating of a fusion reactor of TiC and TiN films by X-ray diffraction 'sin 2 ψ methods' were described. The authors have studied on the effect of conditions of specimen preparation (such as coating method, substrate materials, film thickness and deposition temperature) on the residual stress of TiC and TiN films coated onto Mo, 316LSS and Pocographite by chemical vapor deposition (CVD) and physical vapor deposition (PVD) method. All films prepared in this study were found to have a compressive stresses and the CVD method gave lower residual stress than PVD method. TiC film coated on Mo substrate at 1100 degree C by CVD method showed that residual stress as the film thickness was raised from 14 μm to 60 μm, on the other hand, residual stress by PVD method exhibited a high compressive stresses, this kind of stress was principally the intrinsic stress, and a marked decrease in the residual with raising the deposition temperature (200 degree C∼650 degree C) was demonstrated. Origins of the residual stress were discussed by correlation with differences between thermal expansion coefficients, and also with fabrication methods
Residual stresses in a bulk metallic glass-stainless steel composite

Energy Technology Data Exchange (ETDEWEB)

Aydiner, C.C. [Department of Materials and Science Engineering, Iowa State University, Ames, IA 50011 (United States); Uestuendag, E. [Department of Materials and Science Engineering, Iowa State University, Ames, IA 50011 (United States)]. E-mail: ustundag@iastate.edu; Clausen, B. [Lujan Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hanan, J.C. [Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125 (United States); Winholtz, R.A. [Department of Mechanical and Aerospace Engineering and Research Reactor Center, University of Missouri, Columbia, MO 65211 (United States); Bourke, M.A.M. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Peker, A. [Liquidmetal Technologies, Lake Forest, CA 92630 (United States)

2005-06-15

Bulk metallic glasses (BMGs) are new structural materials with impressive mechanical properties. They can now be cast into large dimensions, which can lead to significant residual stress generation due to thermal tempering. In this process, a surface compression develops balanced with tension in the interior. To evaluate this phenomenon non-destructively, a model cylindrical stainless steel (SS)-BMG composite was prepared and studied using neutron diffraction and finite element (FE) modeling. The residual strain data from the SS obtained by diffraction were used in modeling calculations to show that significant tempering could be achieved in the composite (about -200 MPa surface compression in the SS). The strong bond between the SS and BMG allowed efficient load transfer and facilitated stress generation. The final values of the residual stresses were seen to be relatively insensitive to the high temperature constitutive behavior of the SS due to the physics of the thermal tempering in BMGs. The approach presented here constitutes an effective means to study non-destructively thermal tempering in BMGs.
Residual stresses in a bulk metallic glass-stainless steel composite

International Nuclear Information System (INIS)

Aydiner, C.C.; Uestuendag, E.; Clausen, B.; Hanan, J.C.; Winholtz, R.A.; Bourke, M.A.M.; Peker, A.

2005-01-01

Bulk metallic glasses (BMGs) are new structural materials with impressive mechanical properties. They can now be cast into large dimensions, which can lead to significant residual stress generation due to thermal tempering. In this process, a surface compression develops balanced with tension in the interior. To evaluate this phenomenon non-destructively, a model cylindrical stainless steel (SS)-BMG composite was prepared and studied using neutron diffraction and finite element (FE) modeling. The residual strain data from the SS obtained by diffraction were used in modeling calculations to show that significant tempering could be achieved in the composite (about -200 MPa surface compression in the SS). The strong bond between the SS and BMG allowed efficient load transfer and facilitated stress generation. The final values of the residual stresses were seen to be relatively insensitive to the high temperature constitutive behavior of the SS due to the physics of the thermal tempering in BMGs. The approach presented here constitutes an effective means to study non-destructively thermal tempering in BMGs
Modeling and Parameter Optimization for Surface Roughness and Residual Stress in Dry Turning Process

Directory of Open Access Journals (Sweden)

M. H. El-Axir

2017-10-01

Full Text Available The influence of some turning variables and tool overhang on surface roughness parameters and residual stress induced due to machining 6061-T6 aluminum alloy is investigated in this paper. Four input parameters (cutting speed, feed rate, depth of cut and tool overhang are considered. Tests are carried out by precision turning operation on a lathe. Design of experiment techniques, i.e. response surface methodology (RSM and Taguchi's technique have been used to accomplish the objective of the experimental study. Surface roughness parameters are measured using a portable surface roughness device while residual stresses are measured employing deflection-etching technique using electrochemical analysis. The results obtained reveal that feed and rotational speed play significant role in determining the average surface roughness. Furthermore, the depth of cut and tool overhang are less significant parameters, whereas tool overhang interacts with feed rate. The best result of surface roughness was obtained using low or medium values of overhang with low speed and /or feed rate. Minimum maximum tensile residual stress can be obtained with a combination of tool overhang of 37 mm with very low depth of cut, low rotational speed and feed rate of 0.188 mm/rev.
Measurement of the residual stress distribution in a thick pre-stretched aluminum plate

Science.gov (United States)

Yuan, S. X.; Li, X. Q.; M, S.; Zhang, Y. C.; Gong, Y. D.

2008-12-01

Thick pre-stretched aluminum alloy plates are widely used in aircraft, while machining distortion caused by initial residual stress release in thick plates is a common and serious problem. To reduce the distortion, the residual stress distribution in thick plate must be measured. According to the characteristics of the thick pre-stretched aluminum alloy plate, based the elastic mechanical theory, this article deduces the modified layer-removal strain method adapting two different strain situations, which are caused by tensile and compressive stress. To validate this method, the residual stresses distribution along the thick direction of plate 2D70T351 is measured by this method, it is shown that the new method deduced in this paper is simple and accurate, and is very useful in engineering.
3-D Characteristics of the Residual Stress in the Plate Butt Weld Between SA508 and F316L SS

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyoung Soo; Kim, Tae Ryong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); Park, Jai Hak [Chungbuk National University, Cheongju (Korea, Republic of); Kim, Man Won [GNEC, Daejeon (Korea, Republic of); Cho, Seon Yeong [KLES, Daejeon (Korea, Republic of)

2009-04-15

This study is performed to check the three dimensional characteristics of residual stress in the dissimilar metal weld. Although two dimensional analysis has been widely used for the assessment of weld residual stress, it has limitations to understand the stress distribution of the third direction. 3-D analysis was done to understand residual stress distribution of the welded plate. A simple butt-welded plate was considered to show the stress variation on all direction. A mock-up plate weldment was fabricated with SA-508 and F316L, which are widely used in nuclear power plants. The analysis results were validated with the measured values in the mock-up.
Influence of the microstructural changes and induced residual stresses on tensile properties of wrought magnesium alloy friction stir welds

International Nuclear Information System (INIS)

Commin, Loreleï; Dumont, Myriam; Rotinat, René; Pierron, Fabrice; Masse, Jean-Eric; Barrallier, Laurent

2012-01-01

Highlights: ► Study of AZ31 FSW mechanical behaviour. ► Early yielding occurs in the TMAZ, the nugget and base metal zones undergo almost no plastic strains. ► Texture gradient in the TMAZ localises the deformations in this area. ► Residual stresses have a major influence in FSW mechanical behaviour. - Abstract: Friction stir welding induces a microstructural evolution and residual stresses that will influence the resulting mechanical properties. Friction stir welds produced from magnesium alloy hot rolled plates were studied. Electron back scattered diffraction was used to determine the texture evolution, residual stresses were analysed using X ray diffraction and tensile tests coupled with speckle interferometry were performed. The residual stresses induced during friction stir welding present a major influence on the final mechanical properties.
Modeling of Residual Stress and Machining Distortion in Aerospace Components (PREPRINT)

Science.gov (United States)

2010-03-01

John Gayda, “The Effect of Heat Treatment on Residual Stress and Machining Distortions in Advanced Nickel Base Disk Alloys,” NASA/TM-2001-210717. 2...Wei-Tsu Wu, Guoji Li, Juipeng Tang, Shesh Srivatsa, Ravi Shankar, Ron Wallis, Padu Ramasundaram and John Gayda, “A process modeling system for heat...Materials Processing Technology 98 (2000) 189-195. 6. M.A. Rist, S. Tin, B.A. Roder, J.A. James, and M.R. Daymond , “Residual Stresses in a
Residual stress measurement inside a dissimilar metal weld mock-up of the pressurizer safety and relief nozzle

International Nuclear Information System (INIS)

Campos, Wagner R.C.; Rabello, Emerson G.; Silva, Luiz L.; Mansur, Tanius R.; Martins, Ketsia S.

2015-01-01

Residual stresses are present in materials or structural component in the absence of external loads or changes in temperatures. The most common causes of residual stresses being present are the manufacturing or assembling processes. All manufacturing processes, such as casting, welding, machining, molding, heat treatment, among others, introduces residual stresses into the manufactured object. The residual stresses effects could be beneficial or detrimental, depending on its distribution related to the component or structure, its load service and if it is compressive or tensile. In this work, the residual strains and stresses inside a mock-up that simulates the safety and relief nozzle of Angra 1 Nuclear Power Plant pressurizer were studied. The current paper presents a blind hole-drilling method residual stress measurements both at the inner surface of dissimilar metal welds of dissimilar metal weld nozzle mock-up. (author)
Residual stress measurement inside a dissimilar metal weld mock-up of the pressurizer safety and relief nozzle

Energy Technology Data Exchange (ETDEWEB)

Campos, Wagner R.C.; Rabello, Emerson G.; Silva, Luiz L.; Mansur, Tanius R., E-mail: wrcc@cdtn.br, E-mail: egr@cdtn.br, E-mail: silvall@cdtn.br, E-mail: tanius@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte (Brazil). Servico de Integridade Estrutural; Martins, Ketsia S., E-mail: ketshinoda@hotmail.com [Universidade Federal de Minas Gerais (UFMG), Nelo Horizonte (Brazil). Departamento de Engenharia Metalurgica

2015-07-01

Residual stresses are present in materials or structural component in the absence of external loads or changes in temperatures. The most common causes of residual stresses being present are the manufacturing or assembling processes. All manufacturing processes, such as casting, welding, machining, molding, heat treatment, among others, introduces residual stresses into the manufactured object. The residual stresses effects could be beneficial or detrimental, depending on its distribution related to the component or structure, its load service and if it is compressive or tensile. In this work, the residual strains and stresses inside a mock-up that simulates the safety and relief nozzle of Angra 1 Nuclear Power Plant pressurizer were studied. The current paper presents a blind hole-drilling method residual stress measurements both at the inner surface of dissimilar metal welds of dissimilar metal weld nozzle mock-up. (author)
Assessment of possibility of primary water stress corrosion cracking occurrence based on residual stress analysis in pressurizer safety nozzle of nuclear power plant

International Nuclear Information System (INIS)

Lee, Kyoung Soo; Kim, W.; Lee, Jeong Geun

2012-01-01

Primary water stress corrosion cracking (PWSCC) is a major safety concern in the nuclear power industry worldwide. PWSCC is known to initiate only in the condition in which sufficiently high tensile stress is applied to alloy 600 tube material or alloy 82/182 weld material in pressurized water reactor operating environments. However, it is still uncertain how much tensile stress is required to generate PWSCC or what causes such high tensile stress. This study was performed to predict the magnitude of weld residual stress and operating stress and compare it with previous experimental results for PWSCC initiation. For the study, a pressurizer safety nozzle was selected because it is reported to be vulnerable to PWSCC in overseas plants. The assessment was conducted by numerical analysis. Before performing stress analysis for plant conditions, a preliminary mock-up analysis was done. The result of the preliminary analysis was validated by residual stress measurement in the mockup. After verification of the analysis methodology, an analysis under plant conditions was conducted. The analysis results show that the stress level is not high enough to initiate PWSCC. If a plant is properly welded and operated, PWSCC is not likely to occur in the pressurizer safety nozzle.
Mapping residual stress fields from Vickers hardness indents using Raman microprobe spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sparks, R.G.; Enloe, W.S.; Paesler, M.A.

1988-12-01

Micro-Raman spectroscopy is used to map the residual stress fields in the vicinity of Vickers hardness indents. Both 514.5 and 488.0 nm, light is used to excite the effect and the resulting shifted and broadened Raman peaks are analyzed using computer deconvolution. Half-wave plates are used to vary the orientation of the incident later light`s polarization state with respect to crystal orientation. The Raman scattered light is then analyzed for polarization dependences which are indicative of the various components of the Raman scattering tensor. Such studies can yield valuable information about the orientation of stress components in a well known stress field. The results can then be applied to the determination of stress components in machined semiconductor materials.
Combined effect of electric field and residual stress on propagation of indentation cracks in a PZT-5H ferroelectric ceramic

International Nuclear Information System (INIS)

Huang, H.Y.; Chu, W.Y.; Su, Y.J.; Qiao, L.J.; Gao, K.W.

2005-01-01

The combined effect of electric field and residual stress on propagation of unloaded indentation cracks in a PZT-5 ceramic has been studied. The results show that residual stress itself is too small to induce delayed propagation of the indentation cracks in silicon oil. If applied constant electric field is larger than 0.2 kV/cm, the combined effect of electric field and residual stress can cause delayed propagation of the indentation crack after passing an incubation time in silicon oil, but the crack will arrest after propagating for 10-30 μm because of decrease of the resultant stress intensity factor induced by the field and residual stress with increasing the crack length. The threshold electric field for delayed propagation of the indentation crack in silicon oil is E DP = 0.2 kV/cm. If the applied electric field is larger than 5.25 kV/cm, combined effect of the electric field and residual stress can cause instant propagation of the indentation crack, and under sustained electric field, the crack which has propagated instantly can propagate continuously, until arrest at last. The critical electric field for instant propagation of the indentation crack is E P = 5.25 kV/cm. If the applied electric field is larger than 12.6 kV/cm, the microcracks induced by the electric field initiate everywhere, grow and connect in a smooth specimen, resulting in delayed failure, even without residual stress. The threshold electric field for delayed failure of a smooth specimen in silicon oil is E DF = 12.6 kV/cm and the critical electric field for instant failure is E F = 19.1 kV/cm
Influence of quenching cooling rate on residual stress and tensile properties of 2A14 aluminum alloy forgings

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yu-xun, E-mail: zhangyuxun198@163.com; Yi, You-ping, E-mail: yyp@csu.edu.cn; Huang, Shi-quan, E-mail: huangsqcsu@sina.com; Dong, Fei

2016-09-30

To balance the quenching residual stress and the mechanical properties of aluminum alloys, the influence of cooling rate on the residual stress and tensile properties was investigated by numerical simulation and quenching experiments. During the quenching experiments, 2A14 aluminum alloy samples were treated with different water temperatures (20 °C, 70 °C, 100 °C) and a step quenching process. X-ray diffraction (XRD) was used to measure the residual stress. Prior to them, the quenching sensitivity was studied. For this purpose, the time-temperature-properties (TTP) curves were measured and the alloy microstructure was observed using transmission electron microscopy (TEM). The results indicated that the mechanical properties of 2A14 aluminum alloys were mainly determined by the cooling rate within the quenching sensitive temperature range from 300 to 400 °C. Lower cooling rates reduced the tensile strength and yield strength due to a decrease amount of fine precipitates, and reduced the residual stress with the reduction of plastic strain and the degree of inhomogeneous plastic deformation. In addition, the residual stress changed faster than the tensile properties with decreasing cooling rate. Therefore, warm water (70 °C) was used to balance the residual stress and tensile properties of 140-mm-thick 2A14 aluminum alloy forgings, since it can achieve low cooling rates. Furthermore, by combining this characteristic and the material quenching sensitivity, step quenching produced similar tensile properties and lower residual stress, compared with the sample quenched in warm water (70 °C), by increasing cooling rate within quenching sensitivity range and reducing it in other ranges.
Influence of quenching cooling rate on residual stress and tensile properties of 2A14 aluminum alloy forgings

International Nuclear Information System (INIS)

Zhang, Yu-xun; Yi, You-ping; Huang, Shi-quan; Dong, Fei

2016-01-01

To balance the quenching residual stress and the mechanical properties of aluminum alloys, the influence of cooling rate on the residual stress and tensile properties was investigated by numerical simulation and quenching experiments. During the quenching experiments, 2A14 aluminum alloy samples were treated with different water temperatures (20 °C, 70 °C, 100 °C) and a step quenching process. X-ray diffraction (XRD) was used to measure the residual stress. Prior to them, the quenching sensitivity was studied. For this purpose, the time-temperature-properties (TTP) curves were measured and the alloy microstructure was observed using transmission electron microscopy (TEM). The results indicated that the mechanical properties of 2A14 aluminum alloys were mainly determined by the cooling rate within the quenching sensitive temperature range from 300 to 400 °C. Lower cooling rates reduced the tensile strength and yield strength due to a decrease amount of fine precipitates, and reduced the residual stress with the reduction of plastic strain and the degree of inhomogeneous plastic deformation. In addition, the residual stress changed faster than the tensile properties with decreasing cooling rate. Therefore, warm water (70 °C) was used to balance the residual stress and tensile properties of 140-mm-thick 2A14 aluminum alloy forgings, since it can achieve low cooling rates. Furthermore, by combining this characteristic and the material quenching sensitivity, step quenching produced similar tensile properties and lower residual stress, compared with the sample quenched in warm water (70 °C), by increasing cooling rate within quenching sensitivity range and reducing it in other ranges.

Proposed residual stress model for roller bent wide flange sections

NARCIS (Netherlands)

Spoorenberg, R.C.; Snijder, H.H.; Hoenderkamp, J.C.D.

2011-01-01

The manufacturing process of structural wide flange steel sections introduces residual stresses in the material. These stresses due to hot-rolling or welding influence the inelastic buckling response of structural steel members and need to be taken into account in the design. Based on experimental
Effects on residual stresses of aluminum alloy LC4 by laser shock processing

Science.gov (United States)

Zhang, Yong-kang; Lu, Jin-zhong; Kong, De-jun; Yao, Hui-xue; Yang, Chao-jun

2007-12-01

The influences of processing parameters on laser-induced shock waves in metal components are discussed and analyzed. The effects of different parameters of laser shock processing (LSP) on residual stress of aerospace aluminum alloy LC4 were investigated. LSP was performed by using an Nd: glass phosphate laser with 23 ns pulse width and up to ~45 J pulse energy at power densities above GW/mm -2. Special attention is paid to the residual stresses from laser shock processing. Modification of microstructure, surface morphology by laser shock processing is also discussed. Results to date indicate that laser shock processing has great potential as a means of improving the mechanical performance of components.
Residual stress measurements in the dissimilar metal weld in pressurizer safety nozzle of nuclear power plant

International Nuclear Information System (INIS)

Campos, Wagner R.C.; Rabello, Emerson G.; Mansur, Tanius R.; Scaldaferri, Denis H.B.; Paula, Raphael G.; Souto, Joao P.R.S.; Carvalho Junior, Ideir T.

2013-01-01

Weld residual stresses have a large influence on the behavior of cracking that could possibly occur under normal operation of components. In case of an unfavorable environment, both stainless steel and nickel-based weld materials can be susceptible to stress-corrosion cracking (SCC). Stress corrosion cracks were found in dissimilar metal welds of some pressurized water reactor (PWR) nuclear plants. In the nuclear reactor primary circuit the presence of tensile residual stress and corrosive environment leads to so-called Primary Water Stress Corrosion Cracking (PWSCC). The PWSCC is a major safety concern in the nuclear power industry worldwide. PWSCC usually occurs on the inner surface of weld regions which come into contact with pressurized high temperature water coolant. However, it is very difficult to measure the residual stress on the inner surfaces of pipes or nozzles because of inaccessibility. A mock-up of weld parts of a pressurizer safety nozzle was fabricated. The mock-up was composed of three parts: an ASTM A508 C13 nozzle, an ASTM A276 F316L stainless steel safe-end, an AISI 316L stainless steel pipe and different filler metals of nickel alloy 82/182 and AISI 316L. This work presents the results of measurements of residual strain from the outer surface of the mock-up welded in base metals and filler metals by hole-drilling strain-gage method of stress relaxation. (author)
Residual stresses in surface induction hardening of steels: Comparison between experiment and simulation

International Nuclear Information System (INIS)

Coupard, Dominique; Palin-luc, Thierry; Bristiel, Philippe; Ji, Vincent; Dumas, Christian

2008-01-01

Deep induction hardening has been performed on two batches of smooth cylindrical specimens with a hardening depth respectively around 2 mm and 3 mm. The distributions of axial and circumferential residual stresses are analysed for the two specimen batches by X-ray diffraction technique. The radial normal stress field is estimated through the use of the well known Moore and Evans correction. Finally, the experimental residual stresses are compared with those obtained from a multiphysic finite element modelling of the whole induction treatment process, including electromagnetic, thermal, metallurgical and mechanical phenomena. The simulated residual stress field is in good agreement with X-ray analysis especially at depths lower than one-tenth the specimen diameter. At deeper depths, a correction of the experimental X-ray analysis has been done to obtain realistic values
Consideration of microstructure evolution and residual stress measurement near severe worked surface using high energy x-ray

International Nuclear Information System (INIS)

Hashimoto, Tadafumi; Mochizuki, Masahito; Shobu, Takahisa

2012-01-01

It is necessary to establish a measurement method that can evaluate accurate stress on the surface. However, the microstructure evolution takes place near the surface due to severe plastic deformation, since structural members have been superpositioned a lot of working processes to complete. As well known, a plane stress can't be assumed on the severe worked surface. Therefore we have been proposed the measurement method that can be measured the in-depth distribution of residual stress components by using high energy X-ray from a synchrotron radiation source. There is the combination of the constant penetration depth method and tri-axial stress analysis. Measurements were performed by diffraction planes for the orientation parameter Γ=0.25 of which elastic constants are nearly equal to the mechanical one. The stress components obtained must be converted to the stress components in real space by using optimization technique, since it corresponds to the weighted average stress components associated with the attenuation of X-ray in materials. The predicted stress components distribution agrees very well with the corrected one which was measured by the conventional removal method. To verify the availability of the proposed method, thermal aging variation of residual stress components on the severe worked surface under elevated temperature was investigated using specimen superpositioned working processes (i.e., welding, machining, peening). It is clarified that the residual stress components increase with thermal aging, using the diffraction planes in hard elastic constants to the bulk. This result suggests that the thermal stability of residual stress has the dependence of the diffraction plane. (author)
Prediction of residual stress distribution in multi-stacked thin film by curvature measurement and iterative FEA

International Nuclear Information System (INIS)

Choi, Hyeon Chang; Park, Jun Hyub

2005-01-01

In this study, residual stress distribution in multi-stacked film by MEMS (Micro-Electro Mechanical System) process is predicted using Finite Element Method (FEM). We develop a finite element program for REsidual Stress Analysis (RESA) in multi-stacked film. The RESA predicts the distribution of residual stress field in multi-stacked film. Curvatures of multi-stacked film and single layers which consist of the multi-stacked film are used as the input to the RESA. To measure those curvatures is easier than to measure a distribution of residual stress. To verify the RESA, mean stresses and stress gradients of single and multilayers are measured. The mean stresses are calculated from curvatures of deposited wafer by using Stoney's equation. The stress gradients are calculated from the vertical deflection at the end of cantilever beam. To measure the mean stress of each layer in multi-stacked film, we measure the curvature of wafer with the film after etching layer by layer in multi-stacked film
Predictions and measurements of residual stress in repair welds in plates

Energy Technology Data Exchange (ETDEWEB)

Brown, T.B. [Mitsui Babcock Energy Limited, Technology and Engineering, Porterfield Road, Renfrew, PA4 8DJ, Scotland (United Kingdom)]. E-mail: bbrown@mitsuibabcock.com; Dauda, T.A. [Mitsui Babcock Energy Limited, Technology and Engineering, Porterfield Road, Renfrew, PA4 8DJ, Scotland (United Kingdom); Truman, C.E. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, England (United Kingdom); Smith, D.J. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Memhard, D. [Fraunhofer-Institut fuer Werkstoffmechanik, Freiburg (Germany); Pfeiffer, W. [Fraunhofer-Institut fuer Werkstoffmechanik, Freiburg (Germany)

2006-11-15

This paper presents the work, from the European Union FP-5 project ELIXIR, on a series of rectangular repair welds in P275 and S690 steels to validate the numerical modelling techniques used in the determination of the residual stresses generated during the repair process. The plates were 1,000 mm by 800 mm with thicknesses of 50 and 100 mm. The repair welds were 50%, 75% and 100% through the plate thickness. The repair welds were modelled using the finite element method to make predictions of the as-welded residual stress distributions. These predictions were compared with surface-strain measurements made on the parent plates during welding and found to be in good agreement. Through-thickness residual stress measurements were obtained from the test plates through, and local to, the weld repairs using the deep hole drilling technique. Comparisons between the measurements and the finite element predictions generally showed good agreement, thus providing confidence in the method.
Predictions and measurements of residual stress in repair welds in plates

International Nuclear Information System (INIS)

Brown, T.B.; Dauda, T.A.; Truman, C.E.; Smith, D.J.; Memhard, D.; Pfeiffer, W.

2006-01-01

This paper presents the work, from the European Union FP-5 project ELIXIR, on a series of rectangular repair welds in P275 and S690 steels to validate the numerical modelling techniques used in the determination of the residual stresses generated during the repair process. The plates were 1,000 mm by 800 mm with thicknesses of 50 and 100 mm. The repair welds were 50%, 75% and 100% through the plate thickness. The repair welds were modelled using the finite element method to make predictions of the as-welded residual stress distributions. These predictions were compared with surface-strain measurements made on the parent plates during welding and found to be in good agreement. Through-thickness residual stress measurements were obtained from the test plates through, and local to, the weld repairs using the deep hole drilling technique. Comparisons between the measurements and the finite element predictions generally showed good agreement, thus providing confidence in the method
Mapping residual and internal stress in materials by neutron diffraction

International Nuclear Information System (INIS)

Withers, Ph.J.

2007-01-01

Neutron diffraction provides one of the few means of mapping residual stresses deep within the bulk of materials and components. This article reviews the basic scientific methodology by which internal strains and stresses are inferred from recorded diffraction peaks. Both conventional angular scans and time-of-flight measurements are reviewed and compared. Their complementarity with analogous synchrotron X-ray methods is also highlighted. For measurements to be exploited in structural integrity calculations underpinning the safe operation of engineering components, measurement standards have been defined and the major findings are summarised. Examples are used to highlight the unique capabilities of the method showing how it can provide insights ranging from the basic physics of slip mechanisms in hexagonal polycrystalline materials, through the materials optimisation of stress induced transformations in smart nano-materials, to the industrial introduction of novel friction welding processes exploiting stress residual measurements transferred from prototype sub-scale tests to the joining of full-scale aero-engine assemblies. (author)
Residual stress measurements in a ferritic steel/In625 superalloy dissimilar metal weldment using neutron diffraction and deep-hole drilling

International Nuclear Information System (INIS)

Skouras, A.; Paradowska, A.; Peel, M.J.; Flewitt, P.E.J.; Pavier, M.J.

2013-01-01

This paper reports the use of non-invasive and semi-invasive techniques to measure the residual stresses in a large dissimilar weldment. This took the form of a butt weld between two sections of a P92 steel pipe, joined using an In625 welding consumable. Residual stress measurements have been carried out on the 30 mm thick welded pipe using the deep-hole drilling technique to characterise the through wall section residual stress distribution for the weld metal, HAZ and parent material. In addition, neutron diffraction measurements have been carried out within the weld zone. Diffraction patterns presented a high intensity and sharp peaks for the base P92 steel material. However measurements in the weld superalloy material were proven problematic as very weak diffraction patterns were observed. A thorough examination of the weld material suggested that the likely cause of this phenomenon was texture in the weld material created during the solidification phase of the welding procedure. This paper discusses the challenges in the execution and interpretation of the neutron diffraction results and demonstrates that realistic measurements of residual stresses can be achieved, in complex dissimilar metal weldments. Highlights: ► One of the few papers to measure residual stresses on dissimilar metal welds. ► Paper managed to provide realistic measurements of residual stresses using the DHD and ND technique. ► Results of this study have demonstrated the effect of texture during the ND measurements.
Temperature Field Prediction for Determining the Residual Stresses Under Heat Treatment of Aluminum Alloys

Directory of Open Access Journals (Sweden)

A. V. Livshits

2014-01-01

Full Text Available The article is devoted to non-stationary temperature field blanks from aluminum alloys during heat treatment. It consists of the introduction and two smaller paragraphs. In the introduction the author concerns the influence of residual stresses arising in the manufacturing process of details, on the strength of the whole aircraft construction and, consequently, on their technical and economic parameters, such as weight, reliability, efficiency, and cost. He also notes that the residual stresses appeared during the production of parts change their location, size and direction under the influence of the elastic deformations that occur during the exploitation of aircraft. Redistributed residual stresses may have a chaotic distribution that may cause overlap of these stresses on the stresses caused by the impact of workload of constructions and destruction or damage of aircraft components.The first paragraph is devoted to the existing methods and techniques for determining the residual stresses. The presented methods and techniques are analyzed to show the advantages and disadvantages of each of them. The conclusion is drawn that the method to determine the residual stresses is necessary, its cost is less than those of existing ones, and an error does not exceed 10%.In the second section, the author divides the problem of determining the residual stresses into two parts, and describes the solution methods of the first one. The first problem is to define the temperature field of the work piece. The author uses a Fourier equation with the definition of initial and boundary conditions to describe a mathematical model of the heat cycle of work piece cooling. He draws special attention here to the fact that it is complicated to determine the heat transfer coefficient, which characterizes the process of cooling the work piece during hardening because of its dependence on a number of factors, such as changing temperature-dependent material properties of
Effects of interface edge configuration on residual stress in the bonded structures for a divertor application

International Nuclear Information System (INIS)

Kitamura, K.; Nagata, K.; Shibui, M.; Tachikawa, N.; Araki, M.

1998-01-01

Residual stresses in the interface region, that developed at the cool down during the brazing, were evaluated for several bonded structures to assess the mechanical strength of the bonded interface, using thermoelasto-plastic stress analysis. Normal stress components of the residual stresses around the interface edge of graphite-copper (C-Cu) bonded structures were compared for three types of bonded features such as flat-type, monoblock-type and saddle-type. The saddle-type structure was found to be favorable for its relatively low residual stress, easy fabrication accuracy on bonded interface and armor replacement. Residual stresses around the interface edge in three armor materials/copper bonded structures for a divertor plate were also examined for the C-Cu, tungsten-copper (W-Cu) and molybdenum alloy-copper (TZM-Cu), varying the interface wedge angle from 45 to 135 . An optimal bonded configuration for the least value of residual stress was found to have a wedge angle of 45 for the C-Cu, and 135 for both the W-Cu and TZM-Cu bonded ones. (orig.)
Effect of the weld joint configuration on stressed components, residual stresses and mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Cevik, Bekir; Oezer, Alpay; Oezcatalbas, Yusuf [Gazi Univ., Ankara (Turkey)

2014-03-01

The effect of the weld joint configuration on components has been studied, which are under service loads, under repair or construction and the residual stresses as well as the mechanical properties of the joint have been determined. For this purpose, a horizontal positioned tensile testing device and a semi-automatic MIG welding machine have been used and then the weld joints of the plates were subjected to different elastic stresses. When the temperature of the joined elements decreased to room temperature, applied elastic stresses were released. By this means, the effects of the existing tensile stresses in the joined parts and the tensile stresses created by the welding processes were investigated. The tensile stresses occurring in the joined elements were determined by using the photo-elasticity analysis method and the hole-drilling method. Also, tensile-shear tests were applied in order to determine the effect of permanent tensile loads on the mechanical properties of the joint. Experimental results showed that the application of corner welded lap joints for components under tensile loading significantly decrease the shear strength and yielding capacities of the joint. (orig.)
Analysis of Residual Stress and Deformation of Rolling Strengthen Crankshaft Fillet

Directory of Open Access Journals (Sweden)

Han Shaojun

2016-01-01

Full Text Available Based on the analysis of crankshaft fillet rolling process, used ANSYS finite element analysis software to conduct the elastic-plastic mechanical simulation of crankshaft rolling process, and gained the variation law of the residual stress and plastic deformation in the radial path of the fillet under different rolling laps and rolling pressure. Established the relationship between the rolling pressure and the plastic deformation and residual stress of the fillet, and provided theoretical support for the evaluation and detection of the crankshaft rolling quality.
Influence of heat input and radius to pipe thickness ratio on the residual stresses in circumferential arc welded pipes of API X46 steels

International Nuclear Information System (INIS)

Hemmatzadeh, Majid; Moshayedi, Hessamoddin; Sattari-Far, Iradj

2017-01-01

The present work aims to study residual stresses caused by circumferentially welding of two similar API X46 steel pipes by means of finite element modeling. Considering the metallurgical phase transformations and through thermal-mechanical uncoupled analysis, the 3D modeling was carried out by SYSWELD software. Materialistic thermal and mechanical properties of all phases were defined in terms of temperature as well as phase transformation properties. Residual stress was measured through hole-drilling method. The obtained results were used to verify the finite element model. By means of full factorial experiment designing method, effects of heat input and radius to pipe thickness ratio on maximum values of hoop and axial residual stresses were investigated. The effect of each factor was studied in 3 levels and by 9 experiments. Results of statistical analysis revealed that increase in heat input and radius-thickness ratio would lead to higher values of maximum hoop and axial residual stresses. However, interactions of high level of heat input and a low level of radius-thickness ratio increased inter-pass temperature and consequently caused a sudden raise in maximum values of residual stresses. - Highlights: • A FEM model was developed to simulate welding considering phase transformations. • The obtained residual stresses were validated by experiments. • Effect of heat input and radius-to-thickness ratio on residual stress were investigated. • Increasing heat input for 100% caused increasing hoop and axial residual stress until 200%. • Interaction of high heat input and low R/t causes a sudden increase in axial residual stresses.
Study on residual stress across the pipes' thickness using outer surface rapid heating. Development of pipe outer surface irradiated laser stress improvement process (L-SIP)

International Nuclear Information System (INIS)

Ohta, Takahiro; Terasaki, Toshio

2009-01-01

The new process called L-SIP (outer surface irradiated Laser Stress Improvement Process) is developed to improve the tensile residual stress of the inner surface near the butt welded joints of pipes in the compression stress. The temperature gradient occurs in the thickness of pipes in heating the outer surface rapidly by laser beam. By the thermal expansion difference between the inner surface and the outer surface, the compression plastic strain generates near the outer surface and the tensile plastic strain generates near the inner surface of pipes. The compression stress occurs near the inner surface of pipes by the plastic deformation. In this paper, the theoretical equation which calculates residual stress distribution from the inherent strain distribution in the thickness of pipes is derived. And, the relation between the distribution of temperature and the residual stress in the thickness is examined for various pipes size. (1) By rapidly heating from the outer surface, the residual stress near the inner surface of the pipe is improved to the compression stress. (2) Pipes size hardly affects the distribution of the residual stress in the stainless steel pipes for piping (JISG3459). (3) The temperature rising area from the outside is smaller, the area of the compression residual stress near the inner surface becomes wider. (author)
Measurement of the residual stresses in a PWR Control Rod Drive Mechanism nozzle

OpenAIRE

Coules, Harry; Smith, David

2018-01-01

Residual stress in the welds that attach Control Rod Drive Mechanism nozzles into the upper head of a PWR reactor vessel can influence the vessel's structural integrity and initiate Primary Water Stress Corrosion Cracking. PWSCC at Alloy 600 CRDM nozzles has caused primary coolant leakage in operating PWRs. We have used Deep Hole Drilling to characterise residual stresses in a PWR vessel head. Measurements of the internal cladding and nozzle attachment weld showed that although modest tensile...
Residual stress distribution analysis of heat treated APS TBC using image based modelling.

Science.gov (United States)

Li, Chun; Zhang, Xun; Chen, Ying; Carr, James; Jacques, Simon; Behnsen, Julia; di Michiel, Marco; Xiao, Ping; Cernik, Robert

2017-08-01

We carried out a residual stress distribution analysis in a APS TBC throughout the depth of the coatings. The samples were heat treated at 1150 °C for 190 h and the data analysis used image based modelling based on the real 3D images measured by Computed Tomography (CT). The stress distribution in several 2D slices from the 3D model is included in this paper as well as the stress distribution along several paths shown on the slices. Our analysis can explain the occurrence of the "jump" features near the interface between the top coat and the bond coat. These features in the residual stress distribution trend were measured (as a function of depth) by high-energy synchrotron XRD (as shown in our related research article entitled 'Understanding the Residual Stress Distribution through the Thickness of Atmosphere Plasma Sprayed (APS) Thermal Barrier Coatings (TBCs) by high energy Synchrotron XRD; Digital Image Correlation (DIC) and Image Based Modelling') (Li et al., 2017) [1].
Influences of lumped passes on welding residual stress of a thick-walled nuclear rotor steel pipe by multipass narrow gap welding

Energy Technology Data Exchange (ETDEWEB)

Tan, Long, E-mail: mse.longtan@gmail.com [State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Zhang, Jianxun; Zhuang, Dong [State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Liu, Chuan [Provincial Key Lab of Advanced Welding Technology, Jiangsu University of Science and Technology, Zhenjiang 212003 (China)

2014-07-01

Highlights: • The internal residual stress of the thick-walled pipe is measured by using the local removal blind hole method. • Two lumped-pass models are developed to reduce computational cost. • The effect of lumped passes on the welding residual stress is discussed. • Reasonable lumped-pass model can guarantee the accuracy and improve the computational efficiency. - Abstract: The purpose of this study is to investigate the effect of the lumped passes simulation on the distribution of residual stresses before and after heat treatment in a thick-walled nuclear power rotor pipe with a 89-pass narrow gap welding process. The local removal blind hole method was used to measure internal residual stress of the thick-walled pipe after post weld heat treatment (PWHT). Based on the ANSYS software, a two-dimensional axisymmetric finite element model is employed. Two lumped-pass models of M-5th model (five weld beads as one lumped pass) and M-10th model (ten weld beads as one lumped pass) were developed to reduce computational cost. Based on the results in this study, the distributions of residual stresses of a thick-walled welded pipe before and after PWHT are developed. Meanwhile, the distribution of the through-wall axial residual stress along the weld center line is demonstrated to be a self-equilibrating type. In addition, the investigation results show that reasonable and reliable lumped-pass model can not only guarantee the accuracy of the simulated results, but also improve the computational efficiency in the thermo-elastic–plastic FE analysis procedure. Therefore, from the viewpoint of engineering application the developed lumped-pass computational procedure is a promising and useful method to predict residual stress of large and complex welded structures.
Influences of lumped passes on welding residual stress of a thick-walled nuclear rotor steel pipe by multipass narrow gap welding

International Nuclear Information System (INIS)

Tan, Long; Zhang, Jianxun; Zhuang, Dong; Liu, Chuan

2014-01-01

Highlights: • The internal residual stress of the thick-walled pipe is measured by using the local removal blind hole method. • Two lumped-pass models are developed to reduce computational cost. • The effect of lumped passes on the welding residual stress is discussed. • Reasonable lumped-pass model can guarantee the accuracy and improve the computational efficiency. - Abstract: The purpose of this study is to investigate the effect of the lumped passes simulation on the distribution of residual stresses before and after heat treatment in a thick-walled nuclear power rotor pipe with a 89-pass narrow gap welding process. The local removal blind hole method was used to measure internal residual stress of the thick-walled pipe after post weld heat treatment (PWHT). Based on the ANSYS software, a two-dimensional axisymmetric finite element model is employed. Two lumped-pass models of M-5th model (five weld beads as one lumped pass) and M-10th model (ten weld beads as one lumped pass) were developed to reduce computational cost. Based on the results in this study, the distributions of residual stresses of a thick-walled welded pipe before and after PWHT are developed. Meanwhile, the distribution of the through-wall axial residual stress along the weld center line is demonstrated to be a self-equilibrating type. In addition, the investigation results show that reasonable and reliable lumped-pass model can not only guarantee the accuracy of the simulated results, but also improve the computational efficiency in the thermo-elastic–plastic FE analysis procedure. Therefore, from the viewpoint of engineering application the developed lumped-pass computational procedure is a promising and useful method to predict residual stress of large and complex welded structures

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