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Sample records for welding residual stresses

  1. Residual stresses in welded plates

    Science.gov (United States)

    Bernstein, Edward L.

    1994-01-01

    The purpose of this project was to develop a simple model which could be used to study residual stress. The mechanism that results in residual stresses in the welding process starts with the deposition of molten weld metal which heats the immediately adjacent material. After solidification of weld material, normal thermal shrinkage is resisted by the adjacent, cooler material. When the thermal strain exceeds the elastic strain corresponding to the yield point stress, the stress level is limited by this value, which decreases with increasing temperature. Cooling then causes elastic unloading which is restrained by the adjoining material. Permanent plastic strain occurs, and tension is caused in the region immediately adjacent to the weld material. Compression arises in the metal farther from the weld in order to maintain overall static equilibrium. Subsequent repair welds may add to the level of residual stresses. The level of residual stress is related to the onset of fracture during welding. Thus, it is of great importance to be able to predict the level of residual stresses remaining after a weld procedure, and to determine the factors, such as weld speed, temperature, direction, and number of passes, which may affect the magnitude of remaining residual stress. It was hoped to use traditional analytical modeling techniques so that it would be easier to comprehend the effect of these variables on the resulting stress. This approach was chosen in place of finite element methods so as to facilitate the understanding of the physical processes. The accuracy of the results was checked with some existing experimental studies giving residual stress levels found from x-ray diffraction measurements.

  2. Residual stress simulation of circumferential welded joints

    Directory of Open Access Journals (Sweden)

    Melicher R.

    2007-11-01

    Full Text Available Residual stresses are an important consideration in the component integrity and life assessment of welded structure. The welding process is very complex time dependent physical phenomenon with material nonlinearity. The welding is a thermal process with convection between fluid flow and welding body, between welding bodyand environment. Next type of boundary conditions is radiation and thermo-mechanical contact on the outer surface of gas pipe in the near of weld. The temperature variation so obtained is utilised to find the distribution of the stress field.In this paper, a brief review of weld simulation and residual stress modelling using the finite element method (FEM by commercial software ANSYS is presented. Thermo-elastic-plastic formulations using a von Mises yield criterion with nonlinear kinematics hardening has been employed. Residual axial and hoop stresses obtained from the analysis have been shown. The commercial FEM code ANSYS was used for coupled thermalmechanical analysis.

  3. Patterns of residual stresses due to welding

    Science.gov (United States)

    Botros, B. M.

    1983-01-01

    Residual stresses caused by welding result from the nonuniform rate of cooling and the restrained thermal contraction or non-uniform plastic deformation. From the zone of extremely high temperature at the weld, heat flows into both the adjoining cool body and the surrounding atmosphere. The weld metal solidifies under very rapid cooling. The plasticity of the hot metal allows adjustment initially, but as the structure cools the rigidity of the surrounding cold metal inhibits further contraction. The zone is compressed and the weld is put under tensile stresses of high magnitude. The danger of cracking in these structural elements is great. Change in specific volume is caused by the change in temperature.

  4. The Research of Welding Residual Stress Based Finite Element Method

    Directory of Open Access Journals (Sweden)

    Qinghua Bai

    2013-06-01

    Full Text Available Welding residual stress was caused by local heating during the welding process, tensile residual stress reduce fatigue strength and corrosion resistance, Compressive residual stress decreases stability limit. So it will produce brittle fracture, reduce working life and strength of workpiece; Based on the simulation of welding process with finite element method, calculate the welding temperature field and residual stress, and then measure residual stress in experiments, So as to get the best welding technology and welding parameters, to reduce welding residual stress effective, it has very important significance.

  5. A finite element model for residual stress in repair welds

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Z. [Edison Welding Inst., Columbus, OH (United States); Wang, X.L.; Spooner, S.; Goodwin, G.M.; Maziasz, P.J.; Hubbard, C.R.; Zacharia, T. [Oak Ridge National Lab., TN (United States)

    1996-03-28

    This paper describes a three-dimensional finite element model for calculation of the residual stress distribution caused by repair welding. Special user subroutines were developed to simulate the continuous deposition of filler metal during welding. The model was then tested by simulating the residual stress/strain field of a FeAl weld overlay clad on a 2{1/4}Cr-1 Mo steel plate, for which neutron diffraction measurement data of the residual strain field were available. It is shown that the calculated residual stress distribution was consistent with that determined with neutron diffraction. High tensile residual stresses in both the longitudinal and transverse directions were observed around the weld toe at the end of the weld. The strong spatial dependency of the residual stresses in the region around the weld demonstrates that the common two-dimensional cross-section finite element models should not be used for repair welding analysis.

  6. Residual Stresses and Critical Initial Flaw Size Analyses of Welds

    Science.gov (United States)

    Brust, Frederick W.; Raju, Ivatury, S.; Dawocke, David S.; Cheston, Derrick

    2009-01-01

    An independent assessment was conducted to determine the critical initial flaw size (CIFS) for the flange-to-skin weld in the Ares I-X Upper Stage Simulator (USS). A series of weld analyses are performed to determine the residual stresses in a critical region of the USS. Weld residual stresses both increase constraint and mean stress thereby having an important effect on the fatigue life. The purpose of the weld analyses was to model the weld process using a variety of sequences to determine the 'best' sequence in terms of weld residual stresses and distortions. The many factors examined in this study include weld design (single-V, double-V groove), weld sequence, boundary conditions, and material properties, among others. The results of this weld analysis are included with service loads to perform a fatigue and critical initial flaw size evaluation.

  7. Comparison of Welding Residual Stresses of Hybrid Laser-Arc Welding and Submerged Arc Welding in Offshore Steel Structures

    DEFF Research Database (Denmark)

    Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

    2016-01-01

    induced residual stresses. It is also investigated whether the assumption of residual stresses up to yield strength magnitude are present in welded structures as stated in the design guidelines. The fatigue strength for welded joints is based on this assumption. The two welding methods investigated...... are hybrid laser-arc welding (HLAW) and submerged arc welding (SAW). Both welding methods are applied for a full penetration butt-weld of 10 mm thick plates made of thermomechanically hot-rolled, low-carbon, fine-grain S355ML grade steel used in offshore steel structures. The welding residual stress state...

  8. Residual stress analysis of an overlay weld on a dissimilar metal weld

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kang Soo; Lee, Ho Jin; Lee, Bong Sang (Korea Atomic Energy Research Institute, Daejeon (Korea)); Jung, I.C.; Byeon, J.G.; Park, K.S. (Doosan Heavy Industries and Construction Co., Changwon (Korea)), e-mail: kskim5@kaeri.re.kr

    2009-07-01

    In recent years, a dissimilar metal, Alloy 82/182 welds used to connect stainless steel piping and low alloy steel or carbon steel components in nuclear reactor piping system have experienced a cracking due to a primary water stress corrosion (PWSCC). It is well known that one reason for the cracking is the residual stress by the weld. But, it is difficult to estimate the weld residual stress exactly due to many parameters of a welding. In this paper, the analysis of 3 FEM models is performed to estimate the weld residual stress on a dissimilar metal weld exactly

  9. Numerical Simulation of Multi-repaired Weld Residual Stress

    Institute of Scientific and Technical Information of China (English)

    ZHU Yuan-xiang; ZHAO Xue-rong; ZHANG Xiao-fei; HU Lun-ji

    2004-01-01

    In order to understand the change regulation of residual stress during multi-repaired welding to provide theoretical guidance for correct repaired welding procedure and improvement of joint properties, and to simulate the magnitude and distribution of residual stress using the finite element method (FEM).A model of temperature field of weld-repaired using FEM, which was simplified, was established. The weld stress consists of thermal stress and organization stress. Models of the thermal stress and organization stress were described. ANSYS, a software of finite element, was applied to calculate the stress, BHW35 steel was taken as an example, the simulated and experimental results for the 1st, 3rd and 5th weld-repaired were analyzed, the simulated results are in good agreement with experimental results. It can be concluded that the residual stress in the weld center changes little,and the high residual stress exists in HAZ.And in the same place, the more repaired weld, the higher residual stress,and the area of residual stress becomes wider.

  10. Evaluation of similar metal weld effects on residual stress of nozzle dissimilar metal weld

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Seung Cheon; Jeong, Jae Uk; Chang, Yoon Suk; Kim, Young Jin [Sungkyunkwan Univ., Seoul (Korea, Republic of)

    2008-07-01

    Determination of weld-induced residual stress has been an important issue in nuclear power industry because several failures were reported in dissimilar metal weld parts due to primary water stress corrosion cracking. In this context, a couple of remarkable round robin analyses were conducted to quantify the welding simulation variables and to establish optimized numerical analysis process. The purpose of the present research is to introduce welding simulation results for a safety and relief nozzle, which has a dissimilar metal weld part as well as a similar metal weld part. First, finite element analyses are carried out to calculate residual stresses at the inside of nozzle considering only dissimilar metal welding. Subsequently, residual stresses taking into account both the dissimilar and similar metal welding are computed. The similar metal weld effect is evaluated by comparing these analysis results and technical findings derived from the evaluation are fully discussed.

  11. Distribution Characteristics of Weld Residual Stress on Butt Welded Dissimilar Metal Plate

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyoung Soo; Park, Chi Yong [KEPCO Research Institute, Daejeon (Korea, Republic of); Kim, Maan Won [Korea Hydro and Nuclear Power Co., Seoul (Korea, Republic of); Park, Jai Hak [Chungbuk National University, Cheongju (Korea, Republic of)

    2010-09-15

    In this study, the weld residual stress distribution at a dissimilar-metal welded plate of low alloy carbon steel and stainless steel, which are widely used in nuclear power plants, was characterized. A plate mock-up with butt welding was fabricated using SA 508 low alloy steel and Type 304 stainless steel plates and the residual stresses were measured by the X-ray diffraction method after electrolytic polishing of the plate specimen. Finite element analysis was carried out in order to simulate the butt welding of dissimilar metal plate, and the calculated weld residual stress distribution was compared with that obtained from the measured data. The characteristics of the three-dimensional residual stress distribution in a butt weld of dissimilar metal plates were investigated by comparing the measured and calculated residual stress data.

  12. Prediction of Large Structure Welding Residual Stress by Similitude Principles

    Institute of Scientific and Technical Information of China (English)

    Shude Ji; Liguo Zhang; Xuesong Liu; Jianguo Yang

    2009-01-01

    On basis of the similitude principles, the conception of virtual simulative component and the auxiliary value of welding residual stress, which is deduced by the welding conduction theory, the relation of the welding residual stress between the simulative component and the practical component was attained. In order to verify the correctness of the relation, the investigation was done from the view of the welding experiment and the numerical simulation about the simulative component and the practical component. The results show that the distribution of welding residual stress of the simulative component is the same as that of the practical component. The ratio of welding residual stress attained by the experiment or the simulation method between the practical runner and the simulative component was compared with the ratio obtained by the similitude principles. Moreover, the error is less than 10%. This provides a new idea to predict the welding stress distribution of large practical structure by the contractible physical model, which is important for the welding experiment and the numerical simulation.

  13. Butt-welding Residual Stress of Heat Treatable Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    C.M. Cheng

    2007-01-01

    This study, taking three types of aluminum alloys 2024-T351, 6061-T6 and 7075-T6 as experimental materials, conducted single V-groove GTAW (gas tungsten arc welding) butt-welding to analyze and compare the magnitude and differences of residual stress in the three aluminum alloys at different single V-groove angles and in restrained or unrestrained conditions. The results show that the larger the grooving angle of butt joint, the higher the residual tensile stress. Too small grooving angle will lead to dramatic differences due to the amount of welding bead filler metal and pre-set joint geometry. Therefore, only an appropriate grooving angle can reduce residual stress. While welding, weldment in restrained condition will lead to a larger residual stress. Also, a residual stress will arise from the restraint position. The ultimate residual stress of weldment is determined by material yield strength at equilibrium temperature. The higher the yield strength at equilibrium temperature, the higher the material residual stress. Because of its larger thermal conductivity, aluminum alloy test specimens have small temperature differential. Therefore, the residual tensile stress of all materials is lower than their yield strength.

  14. 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.

  15. Numerical simulation of weld tab length influence on welding residual stress and distortion of aero-engine disk

    Institute of Scientific and Technical Information of China (English)

    Xue-qiu ZHANG; Jian-guo YANG; Xue-song LIU; Xu-hui CHEN; Hong-yuan FANG; Shen QU

    2009-01-01

    In order to control the welding residual stress and distortion to the greatest extent, based on the MSC. MARC software platform and adopting the impending critical value methods gradually, the welding residual stress and distortion are calculated through varying the weld tab length values. The results show that different weld tab lengths only have a slight effect on welding residual stress but a significant effect on welding distortion. According to the calculation results with different weld tab lengths, the critical length value for the 100 mm-length TC4 alloy weld for electron beam welding of an integral disk should be 50 mm or so.

  16. Numerical Simulation of Residual Stresses in Linear Friction Welded Joints

    Directory of Open Access Journals (Sweden)

    R. Nikiforov

    2015-09-01

    Full Text Available A thermo-mechanical model of linear friction welding has been developed. The temperature distribution during the heating process was determined using a one-dimensional model. The distribution of temperature and stress field during the forging phase was determined by solving the coupled problem in ANSYS. The model allows to predict the effect of welding parameters on the stress field, whereas modeling data are consistent with the residual stresses in welded joints of the Ti6Al4V alloy obtained during the experiment.

  17. Residual stress analysis of an Overlay weld and a repair weld on the dissimilar Butt weld

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kang Soo, E-mail: kskim5@kaeri.re.k [Korea Atomic Energy Research Institute, 150, Dukjin-dong, Daejeon 305-353 (Korea, Republic of); Lee, Ho Jin; Lee, Bong Sang [Korea Atomic Energy Research Institute, 150, Dukjin-dong, Daejeon 305-353 (Korea, Republic of); Jung, In Chul; Park, Kwang Soo [Doosan Heavy Industries and Construction Co., 555 Gwigok Dong, Changwon 641-792 (Korea, Republic of)

    2009-12-15

    Both the experiment and FE analysis were performed to estimate the residual stresses at the parts of the dissimilar metal welds. The specimen of the dissimilar Butt welds was manufactured, and the residual stresses of this specimen were measured by the X-ray method and a Hole Drilling Technique. The values measured by two experimental methods showed a big deviation at the SUS 316L plate. Consequently, the experimental methods to estimate the residual stresses are not a superior method. The Butt FEM Model on this specimen was developed and analyzed by the ABAQUS Code. The results of the FE analysis were compared with those of the experimental methods. As a whole, the values of the Butt FEM Model showed a trend which was in agreement with the experimental values and the values of FE analysis were found reasonable. The Repair FEM Model and the Overlay FEM Model were developed and analyzed by the ABAQUS Code. The values of these results were also found reasonable data even if the experimental methods be not performed. Therefore, the residual stresses for the dissimilar metal welds can be estimated by an analysis with an appropriate FEM Model without the experimental methods.

  18. Finite element analysis of welding residual stress of aero engine blisk by controlling heat input

    Institute of Scientific and Technical Information of China (English)

    Zhang Xueqiu; Yang Jianguo; Chen Xuhui; Fang Hongyuan; Qu Shen; Wang Licheng

    2009-01-01

    In order to improve aero engine performance, it is necessary to reduce the welding residual stress of aero engine blisk. In this paper, finite element method was employed to simulate electron beam welding process of blisk, in accordance with the deducing formula (p = kh) , the heat input is changed with the weld depth to control welding residual stress of blisk. The calculation results show that welding residual stress of blisk can be controlled effectively by reducing the heat input on the conditions of meeting the demand of weld penetration and guaranteeing the welding quality, a new theoretical method and some numerical data are provided for controlling welding residual stress of blisk.

  19. 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

  20. Prediction of welding residual stress of dissimilar metal weld of nozzle using finite element analyses

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Nam Su; Kim, Jong Wook; Choi, Suhn; Kim, Tae Wan [KAERI, Daejeon (Korea, Republic of)

    2008-07-01

    The Primary Water Stress Corrosion Cracking (PWSCC) of dissimilar metal weld based on Alloy 82/182 is one of major issues in material degradation of nuclear components. It is well known that the crack initiation and growth due to PWSCC is influenced by material's susceptibility to PWSCC and distribution of welding residual stress. Therefore, modeling the welding residual stress is of interest in understanding crack formation and growth in dissimilar metal weld. Currently in Korea, a numerical round robin study is undertaken to provide guidance on the welding residual stress analysis of dissimilar metal weld. As a part of this effort, the present paper investigates distribution of welding resisual stress of a ferritic low alloy steel nozzle with dissimilar metal weld using Alloy 82/182. Two-dimensional thermo-mechanical finite element analyses are carried out to simulate multi-pass welding process on the basis of the detailed design and fabrication data. The present results are compared with those from other participants, and more works incorporating physical measurements are going to be performed to quantify the uncertainties relating to modelling assumptions.

  1. Prediction of Welding Deformation and Residual Stresses in Fillet Welds Using Indirect Couple Field FE Method

    Directory of Open Access Journals (Sweden)

    Asifa Khurram

    2013-03-01

    Full Text Available Fillet welds are extensively used in shipbuilding, automobile and other industries. Heat concentrated at a small area during welding induces distortions and residual stresses, affecting the structural strength. In this study, indirect coupled-field method is used to predict welding residual stresses and deformation in a fillet joint due to welding on both sides. 3-D nonlinear thermal finite element analysis is performed in ANSYS software followed by a structural analysis. Symmetrical boundary conditions are applied on half of the model for simplification. Results of FE structure analysis predict residual stresses in the specimen. A comparison of simulation results with experimental values proves the authenticity of the technique. The present study can be extended for complex structures and welding techniques.

  2. Influence of Hardening Model on Weld Residual Stress Distribution

    Energy Technology Data Exchange (ETDEWEB)

    Mullins, Jonathan; Gunnars, Jens (Inspecta Technology AB, Stockholm (Sweden))

    2009-06-15

    This study is the third stage of a project sponsored by the Swedish Radiation Safety Authority (SSM) to improve the weld residual stress modelling procedures currently used in Sweden. The aim of this study was to determine which material hardening model gave the best agreement with experimentally measured weld residual stress distributions. Two girth weld geometries were considered: 19mm and 65mm thick girth welds with Rin/t ratios of 10.5 and 2.8, respectively. The FE solver ABAQUS Standard v6.5 was used for analysis. As a preliminary step some improvements were made to the welding simulation procedure used in part one of the project. First, monotonic stress strain curves and a mixed isotropic/kinematic hardening model were sourced from the literature for 316 stainless steel. Second, more detailed information was obtained regarding the geometry and welding sequence for the Case 1 weld (compared with phase 1 of this project). Following the preliminary step, welding simulations were conducted using isotropic, kinematic and mixed hardening models. The isotropic hardening model gave the best overall agreement with experimental measurements; it is therefore recommended for future use in welding simulations. The mixed hardening model gave good agreement for predictions of the hoop stress but tended to under estimate the magnitude of the axial stress. It must be noted that two different sources of data were used for the isotropic and mixed models in this study and this may have contributed to the discrepancy in predictions. When defining a mixed hardening model it is difficult to delineate the relative contributions of isotropic and kinematic hardening and for the model used it may be that a greater isotropic hardening component should have been specified. The kinematic hardening model consistently underestimated the magnitude of both the axial and hoop stress and is not recommended for use. Two sensitivity studies were also conducted. In the first the effect of using a

  3. Three-dimensional finite element analysis for estimation of the weld residual stress in the dissimilar butt weld piping

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyoung Soo; Kim, Man Won; Lee, Sung Ho [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2013-01-15

    Numerous dissimilar metal welds are used to connect carbon steel and stainless steel in nuclear power plants. Recently, some cracks have occurred in the dissimilar metal welds, and welding residual stress is considered as a contributing factor to the cracks. In this study, welding residual stresses in dissimilar butt weld piping were evaluated by the 3-dimensional (3-D) finite element method. Welding residual stresses along the circumference of heat affected zones as well as weld regions were obtained through the analysis, which could not be obtainable with 2-dimensional (2-D) analysis. The differences between 2-D analysis and 3-D analysis are presented in this paper.

  4. NUMERICAL SIMULATION OF CONTROLLING IN TITANIUM ALLOY SHEETS WELDING RESIDUAL STRESS BY TRAILING PEENING

    Institute of Scientific and Technical Information of China (English)

    X.S. Liu; H. Y. Fang; W.L. Xu; Z.B. Dong; D.Y. Yu

    2004-01-01

    It is a promising and new technology to apply welding with trailing peening to control welding stress and distortion of titanium alloy. Numerical simulation of conventional welding and welding with trailing peening of the titanium alloy sheet is carried out,using nonlinear finite element theory and the engineering analysis software MARC.The result shows that welding with trailing peening technology reduces longitudinal residual stress in welding joint effectively, and it is more effective to reduce residual stress to peen the weld than to peen the weld toe. It is a effective result that other technology and method used in welding can never achieved.

  5. Residual stress analysis of 7075 aluminum alloy after vacuum electron beam welding

    Institute of Scientific and Technical Information of China (English)

    Chen Furong; Xie Ruijun; Guo Guifang

    2007-01-01

    The residual stresses distribution of 7075 aluminum alloy in vacuum electron beam welding joint was numerically simulated using nonlinear finite element method. The result shows that the longitudinal residual stress is tension stress along weld center and the stress peak value appears in the middle of the welded seam; the transversal residual stress is compression stress; the residual stress in thickness direction is very small.

  6. 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.

  7. Comparison of Residual Stress Distributions of Similar and Dissimilar Thick Butt-Weld Plates

    Science.gov (United States)

    Suzuki, Hiroshi; Katsuyama, Jinya; Morii, Yukio

    Residual stress distributions of 35 mm thick dissimilar metal butt-weld between A533B ferritic steel and Type 304 austenitic stainless steel (304SS) with Ni alloy welds and similar metal butt-weld of 304SS were measured using neutron diffraction. Effects of differences in thermal expansion coefficients (CTEs) and material strengths on the weld residual stress distributions were discussed by comparison of the residual stress distributions between the similar and dissimilar metal butt-welds. Residual stresses in the similar metal butt-weld exhibited typical distributions found in a thick butt-weld and they were distributed symmetrically on either side of the weld line. Meanwhile, asymmetric residual stress distributions were observed near the root of the dissimilar metal butt-weld, which was caused by differences in CTEs and yield strengths among both parent materials and weld metals. Transverse residual stress distribution of the dissimilar metal butt-weld was similar trend to that of the similar metal butt-weld, since effect of difference in CTEs were negligible, while magnitude of the transverse residual stress near the root depended on the yield strengths of each metal. In contrast, the normal and longitudinal residual stresses in the dissimilar metal butt-weld distributed asymmetrically on either side of weld line due to influence of differences in CTEs.

  8. Finite element analysis of residual stress in the welded zone of a high strength steel

    Indian Academy of Sciences (India)

    Li Yajiang; Wang Juan; Chen Maoai; Shen Xiaoqin

    2004-04-01

    The distribution of the residual stress in the weld joint of HQ130 grade high strength steel was investigated by means of finite element method (FEM) using ANSYS software. Welding was carried out using gas shielded arc welding with a heat input of 16 kJ/cm. The FEM analysis on the weld joint reveals that there is a stress gradient around the fusion zone of weld joint. The instantaneous residual stress on the weld surface goes up to 800 ∼ 1000 MPa and it is 500 ∼ 600 MPa, below the weld. The stress gradient near the fusion zone is higher than any other location in the surrounding area. This is attributed as one of the significant reasons for the development of cold cracks at the fusion zone in the high strength steel. In order to avoid such welding cracks, the thermal stress in the weld joint has to be minimized by controlling the weld heat input.

  9. Measurement of Residual Stress in a Welded Branch Connection and Effects on Fracture Behaviour

    Science.gov (United States)

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

    2010-11-01

    The branch analysed in this paper was not post weld heat treated, resulting in significant residual stresses. Assessment codes assume these to be at, or close to, yield. An integrity assessment of a welded branch connection was carried out using these high assumed residual stresses. The weld then had residual stresses determined by neutron diffraction, performed using ANSTO's residual stress diffractometer, Kowari. The maximum measured residual stress (290 MPa or 60% of yield) was much lower than the yield value assumed by assessment codes. Reanalysing with the actual residual stresses almost doubled the critical crack size, increasing the safety of the connection.

  10. Surface Residual Stresses in Ti-6Al-4V Friction Stir Welds: Pre- and Post-Thermal Stress Relief

    Science.gov (United States)

    Edwards, P.; Ramulu, M.

    2015-09-01

    The purpose of this study was to determine the residual stresses present in titanium friction stir welds and if a post-weld thermal stress relief cycle would be effective in minimizing those weld-induced residual stresses. Surface residual stresses in titanium 6Al-4V alloy friction stir welds were measured in butt joint thicknesses ranging from 3 to 12 mm. The residual stress states were also evaluated after the welds were subjected to a post-weld thermal stress relief cycle of 760 °C for 45 min. High (300-400 MPa) tensile residual stresses were observed in the longitudinal direction prior to stress relief and compressive residual stresses were measured in the transverse direction. After stress relief, the residual stresses were decreased by an order of magnitude to negligible levels.

  11. Neutron diffraction analysis of residual strain/stress distribution in the vicinity of high strength welds

    Directory of Open Access Journals (Sweden)

    Hamák I.

    2010-06-01

    Full Text Available Residual stresses resulting from non homogeneous heat distribution during welding process belong to most significant factor influencing behavior of welded structures. These stresses are responsible for defect occurrence during welding and they are also responsible for crack initiation and propagation at the either static or dynamic load. The significant effect of weld metal chemical composition as well as the effect of fatigue load and local plastic deformation on residual stress distribution and fatigue life have been recognized for high strength steels welds. The changes in residual stress distribution have then positive effect on cold cracking behavior and also on fatigue properties of the welds [1-3]. Several experimental methods, both destructive and non-destructive, such as hole drilling method, X-ray diffraction, neutron diffraction and others, have been used to examine residual stress distribution in all three significant orientations in the vicinity of the welds. The present contribution summarizes the results of neutron diffraction measurements of residual stress distribution in the vicinity of single-pass high-strength-steel welds having different chemical composition as well as the influence of fatigue load and local plastic deformation. It has been observed that the chemical composition of the weld metal has a significant influence on the stress distribution around the weld. Similarly, by aplying both cyclic load or pre-stress load on the specimens, stress relaxation was observed even in the region of approximately 40 mm far from the weld toe.

  12. Mechanism of biaxial pre-stress method on welding residual stress and hot cracks controlling

    Institute of Scientific and Technical Information of China (English)

    LIU Xuesong; ZHOU Guangtao; WANG Ping; LIU Haoyuan; FANG Hongyuan

    2009-01-01

    Based on the conventional uniaxial pre-tensile stress method during welding, this study presents a new method of welding with biaxial pre-stress. With the help of numerical simulation, experiments were carried out on the self-designed device. Except for the control on residual stress and distortion as-welded, the experimental results also show its effect on the prevention of hot cracks, thus this method can make up for the disadvantage of the conventional pre-stress method. Hot cracks

  13. Residual stresses analysis of friction stir welding using one-way FSI simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sung Wook; Jang, Beom Seon [Seoul National University, Seoul (Korea, Republic of); Song, Ha Cheol [Mokpo National University, Muan (Korea, Republic of)

    2015-03-15

    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.

  14. 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.

  15. Residual stress distributions in a P91 steel-pipe girth weld before and after post weld heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Paddea, S., E-mail: s.paddea@open.ac.uk [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Francis, J.A. [School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); Paradowska, A.M. [ISIS Facility, Rutherford-Appleton Laboratory, Didcot OX11 0QX, Oxon (United Kingdom); Bouchard, P.J. [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Shibli, I.A. [European Technology Development Ltd., Leatherhead KT22 7RD, Surrey (United Kingdom)

    2012-02-01

    Highlights: Black-Right-Pointing-Pointer Residual stresses in a pipe girth weld in P91 steel have been measured in both the as-welded and PWHT conditions. Black-Right-Pointing-Pointer The highest tensile residual stresses coincided with the HAZ boundary and the microstructural region that is prone to type IV cracking. Black-Right-Pointing-Pointer Compressive residual stresses were measured in the weld metal, in a location corresponding to the final weld pass. Black-Right-Pointing-Pointer The location of the peak compressive stresses can be explained by the effect of solid-state phase transformation. - Abstract: In this study the residual stresses in a pipe girth weld in a ferritic-martensitic power plant steel were measured by neutron diffraction and compared with the corresponding metallurgical zones in the weld region. It was found that, in both the as-welded and post-weld heat treated condition, the highest tensile stresses resided near the outer boundary of the heat-affected zone (HAZ), and towards the weld root region. Substantial tensile direct and hydrostatic stresses existed across the HAZ, including the fine-grained and intercritically annealed regions, where premature type IV creep failures manifest in 9-12 Cr steel welds. Compressive stresses were found in the weld metal coinciding with the last weld bead to be deposited. Constrained cooling tests on test coupons illustrated that these compressive stresses can be explained in terms of the influence that solid-state phase transformations have on the accumulation of stress in welds.

  16. Discussion and calculation on welding residual longitudinal stress and plastic strain by finite element method

    Institute of Scientific and Technical Information of China (English)

    Hong-yuan FANG; Xue-qiu ZHANG; Jian-guo WANG; Xue-song LIU; Shen QU

    2009-01-01

    In recent years, some researchers have put forward the new viewpoint that the weld is merely formed during the cooling process, not concerned with the heating process. According to this view, it can be concluded that it is not the compressive but the tensile plastic strain that may remain in the weld. To analyze the formation mechanism of the longitudinal residual stress and plastic strain, finite element method (FEM) is employed in this paper to model the welding longitudinal residual stress and plastic strain. The calculation results show that both the residual compressive plastic strain and the tensile stress in the longitudinal direction can be found in the weld.

  17. International Institute of Welding work on residual stress and its application to industry

    Energy Technology Data Exchange (ETDEWEB)

    Janosch, Jean-Jacques [Caterpillar France, 40 Avenue Leon-Blum, 38041 Grenoble (France)], E-mail: janosch_jean-jacques@cat.com

    2008-03-15

    This paper gives an overview of the International Institute of Welding (IIW) activity on residual stress and distortion prediction (RSDP) in welded structures. The overall goal of the activity is to define an IIW recommendation for prediction and determination of welding residual stress and distortion. The three main collaborative activities that were launched to support this goal (a modelling round robin, a measurement technique benchmark and definition of a compendium) are described. It is concluded that significant progress has been achieved by participants to improve the modelling approaches, and to optimize experimental technologies to calculate and measure accurately the residual stress distribution and distortion in welded assemblies.

  18. Calculation of residual stresses by means of a 3D numerical weld simulation

    Energy Technology Data Exchange (ETDEWEB)

    Nicak, Tomas; Huemmer, Matthias [AREVA NP GmbH, Postfach 1109 (Germany)

    2008-07-01

    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)

  19. Effects of stop-start features on residual stresses in a multipass austenitic stainless steel weld

    Energy Technology Data Exchange (ETDEWEB)

    Turski, M., E-mail: Mark.Turski@magnesium-elektron.com [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom); Francis, J.A. [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom)] [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Hurrell, P.R. [Rolls-Royce Plc., Raynesway, Derby DE21 7XX (United Kingdom); Bate, S.K. [Serco Technical Services, Birchwood Park, Warrington, Cheshire WA3 6GA (United Kingdom); Hiller, S. [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Withers, P.J. [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom)

    2012-01-15

    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: Black-Right-Pointing-Pointer In this study the residual stress-field surrounding weld interruptions was measured. Black-Right-Pointing-Pointer Localised stresses were found to increase at weld interruptions. Black-Right-Pointing-Pointer Both ramped and abrupt weld interruptions were investigated. Black-Right-Pointing-Pointer After subsequent weld passes, localised stresses persisted for abrupt interruptions. Black-Right-Pointing-Pointer After subsequent weld passes, localised stresses dissipated for ramped interruptions.

  20. Application of welding simulation to block joints in shipbuilding and assessment of welding-induced residual stresses and distortions

    Directory of Open Access Journals (Sweden)

    Fricke Wolfgang

    2014-06-01

    Full Text Available During ship design, welding-induced distortions are roughly estimated as a function of the size of the component as well as the welding process and residual stresses are assumed to be locally in the range of the yield stress. Existing welding simulation methods are very complex and time-consuming and therefore not applicable to large structures like ships. Simplified methods for the estimation of welding effects were and still are subject of several research projects, but mostly concerning smaller structures. The main goal of this paper is the application of a multi-layer welding simulation to the block joint of a ship structure. When welding block joints, high constraints occur due to the ship structure which are assumed to result in accordingly high residual stresses. Constraints measured during construction were realized in a test plant for small-scale welding specimens in order to investigate their and other effects on the residual stresses. Associated welding simulations were successfully performed with fine-mesh finite element models. Further analyses showed that a courser mesh was also able to reproduce the welding-induced reaction forces and hence the residual stresses after some calibration. Based on the coarse modeling it was possible to perform the welding simulation at a block joint in order to investigate the influence of the resulting residual stresses on the behavior of the real structure, showing quite interesting stress distributions. Finally it is discussed whether smaller and idealized models of definite areas of the block joint can be used to achieve the same results offering possibilities to consider residual stresses in the design process.

  1. 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.

  2. Numerical simulation of dissimilar metal welding and its verification for determination of residual stresses

    Directory of Open Access Journals (Sweden)

    Sz. Szávai

    2016-03-01

    Full Text Available This paper summarizes the results of the through-thickness residual stress distributions on dissimilar metal weld (DMW mock-up. DMWs, as welded joints between ferritic steels and either austenitic stainless steels or nickel-based alloys, are commonly found in piping systems of NPPs as well as in other industrial plants. The welding of the mock-up is simulated by the 3D finite element model using temperature and phase dependent material properties. The commercial finite element code MSC.Marc is used to obtain the numerical results by implementing the Goldak’s double ellipsoidal shaped weld heat source and combined convection radiation boundary conditions. Residual stress measurements are performed on welded joints to validate the simulation results. The validated residual stress distributions can be used for the life time assessment and failure mode predictions of the welded joints.

  3. 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.

  4. 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.

  5. Distortion and residual stresses in laser beam weld shaft-hub joints

    Science.gov (United States)

    Buschenhenke, F.; Hofmann, M.; Seefeld, T.; Vollertsen, F.

    In laser beam welding, a serious challenge is to control the distortion during the process. Understanding the whole process chain in view of different distortion potentials applied in each processing step provides the ability to control the distortion of the welded components. Every manufacturing step induces residual stresses in the component which can be released by the heat of the welding process, while further residual stresses are introduced into the welded parts upon cooling. The laser beam sources of the new generation permit a high power welding process and high beam quality at the same time. These laser beams are capable of producing deep and narrow seams. Thus the thermal strains of the joined parts are expected to be minimized. Especially axial welded shaft-hub joints show an irregular distribution of bending deformation, which is caused by the self-influencing welding gap. This work deals with the investigation of different laser beam sources and their effect on the welding distortion in axial welded shafthub joints made of steel (20MnCr5). The aim of the work done was to achieve minimal distortion after the welding process. To characterize the influences on the distortion behaviour of the welded parts, residual stresses have been determined by neutron diffraction.

  6. Optimisation of process parameters in friction stir welding based on residual stress analysis: a feasibility study

    DEFF Research Database (Denmark)

    Tutum, Cem Celal; Hattel, Jesper Henri

    2010-01-01

    The present paper considers the optimisation of process parameters in friction stir welding (FSW). More specifically, the choices of rotational speed and traverse welding speed have been investigated using genetic algorithms. The welding process is simulated in a transient, two-dimensional sequen......The present paper considers the optimisation of process parameters in friction stir welding (FSW). More specifically, the choices of rotational speed and traverse welding speed have been investigated using genetic algorithms. The welding process is simulated in a transient, two......, and this is presented as a Pareto optimal front. Moreover, a higher welding speed for a fixed rotational speed results, in general, in slightly higher stress levels in the tension zone, whereas a higher rotational speed for a fixed welding speed yields somewhat lower peak residual stress, however, a wider tension zone...

  7. 3D Finite Element Numerical Simulation of Residual Stresses on Electron Beam Welded BT20 Plates

    Institute of Scientific and Technical Information of China (English)

    Lixing HUO; Furong CHEN; Yufeng ZHANG; Li ZHANG; Fangjun LIU; Gang CHEN

    2004-01-01

    A three-dimensional finite-element model (FEM) used for calculating electron beam (EB) welding temperature and stresses fields of thin plates of BT20 titanium has been developed in which the nonlinear thermophysical and thermo-mechanical properties of the material has been considered. The welding temperature field, the distributions of residual stresses in aswelded (AW) and electron beam local post-weld heat treatment (EBLPWHT) conditions have been successfully simulated.The results show that: (1) In the weld center, the maximum magnitude of residual tensile stresses of BT20 thin plates of Ti alloy is equal to 60%~ 70% of its yield strength σs. (2) The residual tensile stresses in weld center can be even decreased after EBLPWHT and the longitudinal tensile stresses are decreased about 50% compared to joints in AW conditions. (3)The numerical calculating results of residual stresses by using FEM are basically in agreement with the experimental results.Combined with numerical calculating results, the effects of electron beam welding and EBLPWHT on the distribution of welding residual stresses in thin plates of BT20 have been analyzed in detail.

  8. Neutron diffraction analysis of residual stresses near unannealed welds in anhydrous ammonia nurse tanks.

    Science.gov (United States)

    Becker, A T; Chumbley, L S; Goettee, D; Russell, A M

    2014-01-01

    Neutron diffraction analysis was employed to measure residual stresses near welds in used anhydrous ammonia nurse tanks. Tensile residual stresses contribute to stress corrosion cracking of nurse tanks, which can cause tanks to release toxic ammonia vapor. The analysis showed that tensile residual stresses were present in the tanks measured, and the magnitudes of these stresses approached the yield strength of the steel. Implications for agricultural safety and health are discussed.

  9. 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.

  10. Weld-induced residual stresses in a prototype dragline cluster and comparison with design codes

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, S.; Semetay, C.; Price, J.W.H.; Nied, H.F. [Concordia University, Montreal, PQ (Canada). Dept. of Mechanical & Industrial Engineering

    2010-02-15

    The Australian coal mining industry employs a large fleet of thin-walled Circular Hollow Section (CHS) welded draglines built of several clusters along the length of the main boom, which are often very heavily overlapped with co-eccentric multiple tubular structures. Heat treatment processes for relieving thermally generated weld-induced residual stresses are usually not employed owing to the high costs and potential dragline downtime. However, it is estimated that these weld-induced residual stresses are usually within a tolerable range and are not the major motivating factor in the initiation and propagation of fatigue-induced cracking. This paper presents the simulation of welding-induced residual stresses in a CHS T-Joint, which would form the first of the four lacings welded on to the main chord of a typical mining dragline cluster. The paper compares numerically generated residual stresses during the welding process in a single weld pass with the approach used in two Standards: (I) R6-Revision 4, Assessment of the Integrity of Structures Containing Defects and (ii) American Petroleum Institute API 579-1/ ASME FFS-1 2007. The comparison attests to the observation that while residual stresses in the fused area at some points could be higher than the yield stress, they are generally not capable of inducing cracks in their own right.

  11. FEM Analysis and Measurement of Residual Stress by Neutron Diffraction on the Dissimilar Overlay Weld Pipe

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kang Soo; Lee, Ho Jin; Woo, Wan Chuck; Seong, Baek Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Byeon, Jin Gwi; Park, Kwang Soo; Jung, In Chul [Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)

    2010-10-15

    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

  12. 3 D FEM analysis of welding residual stress and deformation of aero-engine blisk

    Institute of Scientific and Technical Information of China (English)

    杨建国; 周号; 雷靖; 方洪渊; 张学秋; 曲伸

    2014-01-01

    Aero-engine blisk welded by electron beam welding(EBW)method is a complicated structure.Fixtures were used to control the deformation ofblisk during its manufacturing process.Finite element method was utilized to study the evolution of the welding residual stress and deformation of this structure.In which an attenuation function was applied to the double ellipsoid heat source model based on the characteristic ofEBW,and the effects offixtures on the welding residual stresses and deforamtion were also reserached.The simulation results showed that the temperature contour ofweld cross section vertical to the weld centerline followed a “V”shape.Moreover,large welding residual stress and distortion were found in the interface between blisk and fixtures.The stress concentration was reduced sufficiently in starting and end part ofweldment as the fixtures were removed after welding process,while the removing operation had almost no effects on the welding residual stress in the middle section ofweld bead.

  13. Heat sink welding of austenitic stainless steel pipes to control distortion and residual stress

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, H.; Albert, S.K.; Bhaduri, A.K. [Materials Technology Div., Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2007-07-01

    Construction of India's Prototype Fast Breeder Reactor (PFBR) involves extensive welding of austenitic stainless steels pipes of different dimensions. Due to high thermal expansion coefficient and poor thermal conductivity of this class of steels, welding can result in significant distortion of these pipes. Attempts to arrest this distortion can lead to high levels of residual stresses in the welded parts. Heat sink welding is one of the techniques often employed to minimize distortion and residual stress in austenitic stainless steel pipe welding. This technique has also been employed to repair welding of the piping of the Boiling Water Reactors (BWRs) subjected to radiation induced intergranular stress corrosion cracking (IGSCC). In the present study, a comparison of the distortion in two pipe welds, one made with heat sink welding and another a normal welds. Pipes of dimensions 350{phi} x 250(L) x 8(t) mm was fabricated from 316LN plates of dimensions 1100 x 250 x 8 mm by bending and long seam (L-seam) welding by SMAW process. Two fit ups with a root gap of 2 mm, land height of 1mm and a groove angle of 70 were prepared using these pipes for circumferential seam (C-seam) welding. Dimensions at predetermined points in the fit up were made before and after welding to check the variation in radius, circumference and and ovality of the pipes. Root pass for both the pipe fit up were carried out using conventional GTAW process with 1.6 mm AWS ER 16-8-2 as consumables. Welding of one of the pipe fit ups were completed using conventions GTAW process while the other was completed using heat sink welding. For second and subsequent layers of welding using this process, water was sprayed at the root side of the joint while welding was in progress. Flow rate of the water was {proportional_to}6 1/minute. Welding parameters employed were same as those used for the other pipe weld. Results of the dimensional measurements showed that there is no circumferential shrinkage in

  14. Residual stresses in laser welded ASTM A387 Grade 91 steel plates

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Santosh, E-mail: santosh@barc.gov.in [Bhabha Atomic Research Centre, Mumbai, Maharashtra 400094 (India); Kundu, A. [Materials Engineering, The Open University, Milton Keynes, MK7 6AA (United Kingdom); Venkata, K.A. [Department of Mechanical Engineering, University of Bristol, Bristol, BS8 1TR (United Kingdom); Evans, A. [Institut Laue Langevin, Grenoble (France); Truman, C.E. [Department of Mechanical Engineering, University of Bristol, Bristol, BS8 1TR (United Kingdom); Francis, J.A. [University of Manchester, Manchester, M13 9PL (United Kingdom); Bhanumurthy, K. [Bhabha Atomic Research Centre, Mumbai, Maharashtra 400094 (India); Bouchard, P.J. [Materials Engineering, The Open University, Milton Keynes, MK7 6AA (United Kingdom); Dey, G.K. [Bhabha Atomic Research Centre, Mumbai, Maharashtra 400094 (India)

    2013-07-15

    Residual stresses in 9 mm thick ASTM A387 Grade 91 steel plates, joined using constant power (8 kW) low and high heat input laser welding processes, are characterised using neutron diffraction. The measured longitudinal and normal components of residual stress show a bimodal distribution across the welded joint with a low tensile or compressive trough at the weld centre flanked by high magnitude tensile peaks in parent metal adjacent to the heat affected zone boundaries. The width of the central trough and spread of the outboard tensile zones are significantly greater for the high heat input weld. In both cases, the stress distributions can be explained by the strains associated with the austenite to martensite solid-state transformation as the joint cools after welding.

  15. Influence of Material Model on Prediction Accuracy of Welding Residual Stress in an Austenitic Stainless Steel Multi-pass Butt-Welded Joint

    Science.gov (United States)

    Deng, Dean; Zhang, Chaohua; Pu, Xiaowei; Liang, Wei

    2017-03-01

    Both experimental method and numerical simulation technology were employed to investigate welding residual stress distribution in a SUS304 steel multi-pass butt-welded joint in the current study. The main objective is to clarify the influence of strain hardening model and the yield strength of weld metal on prediction accuracy of welding residual stress. In the experiment, a SUS304 steel butt-welded joint with 17 passes was fabricated, and the welding residual stresses on both the upper and bottom surfaces of the middle cross section were measured. Meanwhile, based on ABAQUS Code, an advanced computational approach considering different plastic models as well as annealing effect was developed to simulate welding residual stress. In the simulations, the perfect plastic model, the isotropic strain hardening model, the kinematic strain hardening model and the mixed isotropic-kinematic strain hardening model were employed to calculate the welding residual stress distributions in the multi-pass butt-welded joint. In all plastic models with the consideration of strain hardening, the annealing effect was also taken into account. In addition, the influence of the yield strength of weld metal on the simulation result of residual stress was also investigated numerically. The conclusions drawn by this work will be helpful in predicting welding residual stresses of austenitic stainless steel welded structures used in nuclear power plants.

  16. Residual Stress and Fatigue Strength of Hybrid Laser-MIG-Welded A7N01P-T4

    Science.gov (United States)

    Wang, Qiuying; Chen, Hui; Qiu, Peixian; Zhu, Zongtao

    2017-02-01

    A7N01P-T4 aluminum alloy is widely used in some important welded components of high-speed trains. The hybrid laser-metal inert gas (MIG) welding process was studied to solve problems associated with the MIG welding process, such as low welding efficiency, high residual stress and deformation, and serious loss of strength. A high-speed camera, a voltage and current collection system, and NI DAQ were used to acquire arc profiles, welding voltage, and welding current simultaneously. Thermal cycle tests were carried out. Residual stresses induced by the welding process and fatigue strength of the joint were investigated. Large-size fatigue specimens were used in fatigue tests. The results show that the energy of the hybrid welding process is focused, and the power density of hybrid welding process is intense. The heat input per unit of the hybrid welding process is only half of that of the MIG welding process. Compared with the MIG welded joint, the overall residual stress level of the hybrid-welded joint is lower. The peak longitudinal stress of the hybrid-welded joint is reduced by 20 pct. The fatigue strength of hybrid joints is 14 pct higher than that of MIG-welded joints. Narrow weld and HAZ, weak softening behavior, and low residual stress level are the causes of the improvement of fatigue strength.

  17. Residual Stress and Fatigue Strength of Hybrid Laser-MIG-Welded A7N01P-T4

    Science.gov (United States)

    Wang, Qiuying; Chen, Hui; Qiu, Peixian; Zhu, Zongtao

    2016-09-01

    A7N01P-T4 aluminum alloy is widely used in some important welded components of high-speed trains. The hybrid laser-metal inert gas (MIG) welding process was studied to solve problems associated with the MIG welding process, such as low welding efficiency, high residual stress and deformation, and serious loss of strength. A high-speed camera, a voltage and current collection system, and NI DAQ were used to acquire arc profiles, welding voltage, and welding current simultaneously. Thermal cycle tests were carried out. Residual stresses induced by the welding process and fatigue strength of the joint were investigated. Large-size fatigue specimens were used in fatigue tests. The results show that the energy of the hybrid welding process is focused, and the power density of hybrid welding process is intense. The heat input per unit of the hybrid welding process is only half of that of the MIG welding process. Compared with the MIG welded joint, the overall residual stress level of the hybrid-welded joint is lower. The peak longitudinal stress of the hybrid-welded joint is reduced by 20 pct. The fatigue strength of hybrid joints is 14 pct higher than that of MIG-welded joints. Narrow weld and HAZ, weak softening behavior, and low residual stress level are the causes of the improvement of fatigue strength.

  18. Through-Thickness Measurements of Residual Stresses in an Overlay Dissimilar Weld Pipe using Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Wan Chuck; EM, Vyacheslav; Lee, Ho Jin; Kim, Kang Soo; Kang, Mi Hyun; Joo, Jong Dae; Seong, Baek Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Byeon, Jin Gwi; Park, Kwang Soo [Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)

    2010-10-15

    The distribution of residual stresses in dissimilar material joints has been extensively studied because of the wide applications of the dissimilar welds in many inevitable complex design structures. Especially the cracking of dissimilar welding has been a long standing issue of importance in many components of the power generation industries such as nuclear power plant, boiling pressure system, and steam generators. In particular, several failure analysis and direct observations have shown that critical fractures have frequently occurred in one side of the dissimilar welded parts. For example, the heat-affected zone on the ferrite steel side is known to critical in many dissimilar welding pipes when ferrite (low carbon steel) and austenite (stainless) steels are joined. The main cause of the residual stresses can be attributed to the mismatch in the coefficient of thermal expansion between the dissimilar metals (ferrite and austenite). Additional cladding over circumferential welds is known to reinforce the mechanical property due to the beneficial compressive residual stress imposed on the weld and heat-affected zone. However, science-based quantitative measurement of the through thickness residual stress distribution is very limited in literature. The deep penetration capability of neutrons into most metallic materials makes neutron diffraction a powerful tool to investigate and map the residual stresses of materials throughout the thickness and across the weld. Furthermore, the unique volume averaged bulk characteristic of materials and mapping capability in three dimensions are suitable for the engineering purpose. Thus, the neutron-diffraction measurement method has been selected as the most useful method for the study of the residual stresses in various dissimilar metal welded structures. The purpose of this study is to measure the distribution of the residual stresses in a complex dissimilar joining with overlay in the weld pipe. Specifically, we measured

  19. 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.

  20. 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.

  1. Residual stress measurements in the dissimilar metal weld in pressurizer safety nozzle of nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Wagner R.C.; Rabello, Emerson G.; Mansur, Tanius R.; Scaldaferri, Denis H.B.; Paula, Raphael G., E-mail: wrcc@cdtn.br, E-mail: egr@cdtn.br, E-mail: tanius@cdtn.br, E-mail: dhbs@cdtn.br, E-mail: tanius@cdtn.br, E-mail: raphaelmecanica@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Souto, Joao P.R.S.; Carvalho Junior, Ideir T., E-mail: joprocha@yahoo.com.br, E-mail: ideir_engenharia@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Metalurgica

    2013-07-01

    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)

  2. An Evaluation on the Residual Stresses Induced by EFR Welding of CEDM Nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Ho; Park, Gi Yeol; Kim, Tae Ryong [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2015-10-15

    In this paper, carried out the welding analysis to use the SYSWELD as welding interpretation code based on the reactor upper head nozzle. In this paper, evaluated the residual stress in CEDM nozzle by EFR through the SYSWELD which is the welding interpretation code. The conclusion are same as below. 1) When comparing with Hoop Stress and Axial Stress by J-Groove and EFR, after welding residual stress by EFR is lower than after J-Groove. 2) After EFR, it was confirmed that the tensile stress is reduced after increasing over the point3. The PWSCC of Dissimilar Metal Zone of reactor can degrade the integrity of the main device in nuclear power plant, and according to the power plant stopped for inspection, it can cause an enormous amount of lost sales when the crack is occurred. Various methods have been developed to reduce residual stress to prevent the PWSCC like Weld Overlay (WOL), Mechanical Stress Improvement Process (Msp), Laser Peening, Inlay Weld, etc. Among them, Wol is the most commonly used welding method in nuclear power plant. When performing a Wol, structure rigidity will be increase, and residual stress of welding zone will be changed into compressive stress from the tensile stress. This has the advantage that improved resistance to PWSCC. The most commonly used material in nuclear power plant is Inconel 600. Inconel 600 consist of a Ni-Cr-Fe and it has 14-17% of Cr content, 10% of Fe content and susceptible to PWSCC. The more Cr content is more stronger against PWSCC. Inconel 690 which has 2 times more Cr content than Inconel 600 has very strong resistance to PWSCC than Inconel 600. Embedded Flaw Repair (EFR) has been developed in Westinghouse by 1994. The welding metal with high corrosion resistance is embedded on the surface of component, and could protect cracking part from the PWSCC. It is permanent repair method that isolates the flaw from the environment, eliminating further crack propagation due to PWSCC. EFR method is that at least three layers

  3. Prediction of Welding Residual Stress in 2. 25Cr-1Mo Steel Pipe

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A numerical analysis method was proposed to predict the welding residual stress in 2.25Cr-1Mo steel pipe considering solid-state phase transformations. A thermal elastic plastic finite element (FE) model considering effects of martensite transformation was developed based on commercial ABAQUS software. Continuous cooling transformation (CCT) diagrams were employed to simulate the fraction of martensite in fusion zone, coarsegrained heat affected zone and fine-grained heat affected zone. The Koistinen-Marburger relationship was used to trace the formation of martensite. The effects of both volume change and yield strength change due to phase transformation on welding residual stress were considered using the proposed FE model. The result shows that the phase transformation has significant effects on the welding residual stress in multi-pass butt weld of pipe. The predicted simulation results by the proposed numerical method are generally in good agreement with experimental results.

  4. Numerical Analysis of Welding Residual Stress and Distortion in Laser+GMAW Hybrid Welding of Aluminum Alloy T-Joint

    Institute of Scientific and Technical Information of China (English)

    Guoxiang XU; Chuansong WU; Xuezhou MA; Xuyou WANG

    2013-01-01

    A 3-D finite element model is developed to predict the temperature field and thermally induced residual stress and distortion in laser+GMAW hybrid welding of 6061-T6 aluminum alloy T-joint.And the characteristics of residual stress distribution and deformation are numerically investigated.In the simulation,the heat source model takes into account the effect of joint geometric shape and welding torch slant on the heat flux distribution and a sequentially coupled thermo-mechanical method is used.The calculated results show that higher residual stress is distributed in and surround the weld zone.Its peak value is very close to the yield strength of base metal.Besides,a large deformation appears in the middle and rear part of the weldment.

  5. NUMERICAL ANALYSIS OF RESIDUAL STRESSES IN TITANIUM ALLOY DURING ELECTRON BEAM LOCAL POST-WELD HEAT TREATMENT

    Institute of Scientific and Technical Information of China (English)

    Chen Furong; Huo Lixing; Zhang Yufeng; Liu Fangjun; Chen Gang

    2005-01-01

    The distributions of temperature and residual stresses in thin plates of BT20 titanium alloy are numerically analyzed by three-dimensional finite element software during electron beam welding and electron beam local post-weld heat treatment (EBLPWHT). Combined with numerical calculating results, the effects of different EBLPWHT mode and parameters, including heat treating position,heating width and heating time, on the distribution of welding residual stresses are analyzed. The results show that, the residual tensile stresses in weld center can be largely decreased when the weld is heat treated at back preface of the plate. The numerical results also indicated that the magnitude of the residual longitudinal stresses of the weld and the zone vicinity of the weld is decreased, and the range of the residual longitudinal stresses is increased along with the increase of heating width and heating time.

  6. Microstructural and Residual Stress Development due to Inertia Friction Welding in Ti-6246

    Science.gov (United States)

    Attallah, Moataz M.; Preuss, Michael; Boonchareon, Chatri; Steuwer, Axel; Daniels, John E.; Hughes, Darren J.; Dungey, Christopher; Baxter, Gavin J.

    2012-09-01

    A thorough investigation has been performed to assess the microstructural properties, mechanical properties (hardness and elastic modulus), and residual stress development in Ti-6Al-2Sn-4Zr-6Mo (Ti-6246) inertia friction welds in the as-welded and postweld heat-treated conditions. It was evident that the thermomechanical deformation in the weld region occurred above the β transus, forming dynamically recrystallized β grains and precipitating acicular α within the β grains, which resulted in a localized hardness increase. In the heat-affected zone, a ghost microstructure of the base metal formed because of the absence of sufficient time for diffusion, resulting in Mo segregation in the prior primary α plates. Energy-dispersive synchrotron X-ray diffraction and neutron diffraction were used to assess the residual stress development in the three principal directions. The variation in the unstrained lattice parameters across the weld regions was established by imposing a stress balance on the axial stress component in the radial direction. It was found that the maximum stresses occurred in the hoop direction, with significantly lower stresses present in the radial and axial directions. The maximum tensile hoop stresses were located at ~4 mm from the weld centerline and not at the dynamically recrystallized β-rich weld zone. This was associated with the α → β phase transformation and the subsequent acicular α precipitation within the region surrounding the weld centerline.

  7. Welding sequence effects on residual stress distribution in offshore wind monopile structures

    Directory of Open Access Journals (Sweden)

    Ali Mehmanparast

    2016-01-01

    Full Text Available Residual stresses are often inevitably introduced into the material during the fabrication processes, such as welding, and are known to have significant effects on the subsequent fatigue crack growth behavior of welded structures. In this paper, the importance of welding sequence on residual stress distribution in engineering components has been reviewed. In addition, the findings available in the literature have been used to provide an accurate interpretation of the fatigue crack growth data on specimens extracted from the welded plates employed in offshore wind monopile structures. The results have been discussed in terms of the role of welding sequence in damage inspection and structural integrity assessment of offshore renewable energy structures.

  8. Finite Element Simulation of Residual Stresses in Butt Welding of Two AISI 304 Stainless Steel Plates

    Directory of Open Access Journals (Sweden)

    Gurinder Singh Brar

    2013-06-01

    Full Text Available Welding is one of the most reliable and efficient permanent metal joining processes in the industry. When two plates are joined by welding, a very complex thermal cycle is applied to the weldment. Thermal energy applied results in irreversible elastic-plastic deformation and consequently gives rise to the residual stresses in and around fusion zone and heat affected zone (HAZ. It is well established fact that structural integrity of components is substantially affected by the residual stresses when subjected to thermal and structural loads. Presence of residual stresses may be beneficial or harmful for the structural components depending on the nature and magnitude of residual stresses. Using finite element based commercially available software, coupled thermal-mechanical three dimensional finite element model was developed by making an approximate geometry of the butt welded joint. Finite element analysis was performed to understand the complete nature of residual stresses in manual metal arc welded joint of AISI 304 stainless steel plate. Variation of residual stress in the plates in the heat affected zone was also being studied. The results obtained by finite element method agree well with those from X-ray diffraction method as published in literature for the prediction of residual stresses.

  9. Residual Stresses in Inertia-Friction-Welded Dissimilar High-Strength Steels

    Science.gov (United States)

    Moat, R. J.; Hughes, D. J.; Steuwer, A.; Iqbal, N.; Preuss, M.; Bray, S. E.; Rawson, M.

    2009-09-01

    The welding of dissimilar alloys is seen increasingly as a way forward to improve efficiencies in modern aeroengines, because it allows one to tailor varying material property demands across a component. Dissimilar inertia friction welding (IFW) of two high-strength steels, Aermet 100 and S/CMV, has been identified as a possible joint for rotating gas turbine components and the resulting welds are investigated in this article. In order to understand the impact of the welding process and predict the life expectancy of such structures, a detailed understanding of the residual stress fields present in the welded component is needed. By combining energy-dispersive synchrotron X-ray diffraction (EDSXRD) and neutron diffraction, it has been possible to map the variations in lattice spacing of the ferritic phase on both sides of two tubular Aermet 100-S/CMV inertia friction welds (as-welded and postweld heat-treated condition) with a wall thickness of 37 mm. Laboratory-based XRD measurements were required to take into account the variation in the strain-free d-spacing across the weld region. It was found that, in the heat-affected zone (HAZ) slightly away from the weld line, residual stress fields showed tensile stresses increasing most dramatically in the hoop direction toward the weld line. Closer to the weld line, in the plastically affected zone, a sharp drop in the residual stresses was observed on both sides, although more dramatically in the S/CMV. In addition to residual stress mapping, synchrotron XRD measurements were carried out to map microstructural changes in thin slices cut from the welds. By studying the diffraction peak asymmetry of the 200- α diffraction peak, it was possible to demonstrate that a martensitic phase transformation in the S/CMV is responsible for the significant stress reduction close to the weld line. The postweld heat treatment (PWHT) chosen to avoid any overaging of the Aermet 100 and to temper the S/CMV martensite resulted in little

  10. X-Ray diffraction technique applied to study of residual stresses after welding of duplex stainless steel plates

    Energy Technology Data Exchange (ETDEWEB)

    Monin, Vladimir Ivanovitch; Assis, Joaquim Teixeira de [Instituto Politecnico do Rio e Janeiro (IPRJ), Nova Friburgo, RJ (Brazil); Lopes, Ricardo Tadeu; Turibus, Sergio Noleto; Payao Filho, Joao C., E-mail: sturibus@nuclear.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil)

    2014-08-15

    Duplex stainless steel is an example of composite material with approximately equal amounts of austenite and ferrite phases. Difference of physical and mechanical properties of component is additional factor that contributes appearance of residual stresses after welding of duplex steel plates. Measurements of stress distributions in weld region were made by X-ray diffraction method both in ferrite and austenite phases. Duplex Steel plates were joined by GTAW (Gas Tungsten Arc Welding) technology. There were studied longitudinal and transverse stress components in welded butt joint, in heat affected zone (HAZ) and in points of base metal 10 mm from the weld. Residual stresses measured in duplex steel plates jointed by welding are caused by temperature gradients between weld zone and base metal and by difference of thermal expansion coefficients of ferrite and austenite phases. Proposed analytical model allows evaluating of residual stress distribution over the cross section in the weld region. (author)

  11. Characterization of Residual Stress as a Function of Friction Stir Welding Parameters in ODS Steel MA956

    Science.gov (United States)

    2013-06-01

    OF RESIDUAL STRESS AS A FUNCTION OF FRICTION STIR WELDING PARAMETERS IN ODS STEEL MA956 by Martin S. Bennett June 2013 Thesis Advisor...characterizes the residual stresses generated by friction stir welding of ODS steel MA956 as a function of heat index. The heat index of a weld is used to...determine relative heat input among different friction stir welding conditions. It depends on a combination of the rotational speed and traverse, or

  12. 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)

  13. Weld Residual Stress and Distortion Analysis of the ARES I-X Upper Stage Simulator (USS)

    Science.gov (United States)

    Raju, Ivatury; Dawicke, David; Cheston, Derrick; Phillips, Dawn

    2008-01-01

    An independent assessment was conducted to determine the critical initial flaw size (CIFS) for the flange-to-skin weld in the Ares I-X Upper Stage Simulator (USS). The Ares system of space launch vehicles is the US National Aeronautics and Space Administration s plan for replacement of the aging space shuttle. The new Ares space launch system is somewhat of a combination of the space shuttle system and the Saturn launch vehicles used prior to the shuttle. Here, a series of weld analyses are performed to determine the residual stresses in a critical region of the USS. Weld residual stresses both increase constraint and mean stress thereby having an important effect on fatigue and fracture life. While the main focus of this paper is a discussion of the weld modeling procedures and results for the USS, a short summary of the CIFS assessment is provided.

  14. The inclusion of weld residual stress in fracture margin assessments of embrittled nuclear reactor pressure vessels

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, T.L.; Bass, B.R.; McAfee, W.J.

    1998-01-01

    Analyses were performed to determine the impact of weld residual stresses in a reactor pressure vessel (RPV) on (1) the generation of pressure temperature (P-T) curves required for maintaining specified fracture prevention margins during nuclear plant startup and shutdown, and (2) the conditional probability of vessel failure due to pressurized thermal shock (PTS) loading. The through wall residual stress distribution in an axially oriented weld was derived using measurements taken from a shell segment of a canceled RPV and finite element thermal stress analyses. The P-T curve derived from the best estimate load analysis and a t / 8 deep flaw, based on K{sub Ic}, was less limiting than the one derived from the current methodology prescribed in the ASME Boiler and Pressure Vessel Code. The inclusion of the weld residual stresses increased the conditional probability of cleavage fracture due to PTS loading by a factor ranging from 2 to 4.

  15. Residual stress relaxation in typical weld joints and its effect on fatigue and crack growth

    Institute of Scientific and Technical Information of China (English)

    Liangbi LI; Zhengquan WAN; Zili WANG; Chunyan JI

    2009-01-01

    Many factors influence the fatigue and crack growth behavior of welded joints. Some structures often undergo fairly large static loading before they enter service or variable amplitude cyclic loading when they are in service. The combined effect of both applied stress and high initial residual stress is expected to cause the residual stresses relaxation. Only a few papers seem to deal with appropriate procedures for fatigue analysis and crack growth by considering the combined effect of variable amplitude cyclic loading with residual stresses relaxation. In this article, some typical welded connections in ship-shaped structures are investigated with 3-D elastic-plastic finite element analysis. The effect of residual stress relaxation, initial residual stress, and the applied load after variable amplitude cyclic loading is revealed, and a formula for predicting the residual stress at hot spot quantitatively is proposed. Based on the formula, an improved fatigue procedure is introduced. Moreover, crack growth of typical weld joints considering residual stresses relaxation is studied.

  16. Residual stress analysis of aluminium welds with high energy synchrotron radiation at the HARWI II beamline

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Torben; Martins, Rene V.; Schreyer, Andreas [GKSS Research Centre, Geesthacht (Germany)

    2008-07-01

    In civil aircraft production advanced welding techniques, like laser beam welding or friction stir welding, are used to reduce weight and production costs. By the welding process residual stresses are introduced in the weld zone and the surrounding area. These stresses may depend on diverse factors and can have disadvantageous influence on the service performance of the weld. For strain scanning GKSS research centre built up the high energy materials science beamline HARWI II at HASYLAB. The use of high energetic photons from about 80 keV-120 keV enables diffraction experiments in transmission geometry, which provides the information about the macroscopic stresses. A large sample-detector-distance ensures a high angular resolution for the peak position determination. The heavy load diffractometer allows making use of massive sample environments. For example laser beam welded t- and butt-joints were investigated with high spatial resolution. The large grain size of the specimen makes the measurements with high spatial resolution more difficult due to the poor grain statistics. The influences of the gauge volume size and grain statistics on the strain measurements were systematically investigated. For the t-joint configuration two dimensional stress maps were calculated from the data. For the near future an in-situ FSW experiment is planed to investigate the metallophysical processes during the welding.

  17. Procedure for Computing Residual Stresses from Neutron Diffraction Data and its Application to Multi-Pass Dissimilar Weld

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei [ORNL; Feng, Zhili [ORNL; Crooker, Paul [Electric Power Research Institute (EPRI)

    2011-01-01

    Neutron diffraction is a powerful tool for non-destructive measurement of internal residual stresses of welded structures. The conventional approach for determination of residual stresses requires the knowledge of stress-free lattice spacing a priori. For multiple-pass dissimilar metal welds common to nuclear reactor pipeline systems, the stress-free lattice parameter is a complex function of position due to the chemistry inhomogeneity in the weld region and can be challenging to determine experimentally. This paper presents a new approach to calculate the residual stress field in dissimilar welds without the use of stress-free lattice parameter. The theoretical basis takes advantage of the fact that the normal component of welding residual stresses is typically small for thin plate or pipe welds. The applicability of the new approach is examined and justified in a multi-pass dissimilar metal weld consisting of a stainless steel plate and a nickel alloy filler metal. The level of uncertainties associated with this new approach is assessed. Neutron diffraction experiment is carried out to measure the lattice spacing at various locations in the dissimilar weld. A comb-shaped specimen, electro-discharge machined from a companion weld, is used to determine the stress-free lattice spacing. The calculated results from the new approach are consistent with those from the conventional approach. The new approach is found to be a practical method for determining the two in-plane residual stress components in thin plate or pipe dissimilar metal welds.

  18. Thermo-mechanical Modeling for Residual Stresses of Friction Stir Welding of Dissimilar Alloys

    OpenAIRE

    ABDUL ARIF; ABHISHEK; K. N. Pandey

    2013-01-01

    Friction stir welding is an advanced joining process that has been used for high production since 1996. FSW produces a weld that is strong than the base material because melting does not occur and joining takes place below the melting temperature of the material. FSW produces no fumes and can join aluminum alloys, magnesium, steels, copper and titanium. In this study, a thermo-mechanical model with improved potential is developed to study the formation of residual stress field in dissimilar ...

  19. A round-robin analysis of temperature and residual stresses in dissimilar metal weld

    Energy Technology Data Exchange (ETDEWEB)

    Song, Min Sup; Kang, Sun Ye; Park, June Soo; Sohn, Gap Heon [Korea Power Engineering Company, Inc., Daejeon (Korea, Republic of)

    2008-07-01

    DMWs are common feature of the PWR in the welded connections between carbon steel and stainless steel piping. The nickel-based weld metal, Alloy 82/182, is used for welding the dissimilar metals and is known to be susceptible to PWSCC. A round-robin program has been implemented to benchmark the numerical simulation of the transient temperature and weld residual stresses in the DMWs. To solve the round-robin problem related to pressurizer safety and relief nozzle, the thermal elasto-plastic analysis is performed in the DMW by using the FEM. The welding includes both the DMW of the nozzle to safe-end and the SMW of the safe-end and piping. Major results of the analyses are discussed: The axial and circumferential residual stresses are found to be -88MPa(225MPa) and -38MPa(293MPa) on the inner surface of the DMW; where the values in parenthesis are the residual stresses after the DMW. Thermo-mechanical interaction by the SMW has a significant effect on the residual stress fields in the DMW.

  20. Optimization of the Process Parameters for Controlling Residual Stress and Distortion in Friction Stir Welding

    DEFF Research Database (Denmark)

    Tutum, Cem Celal; Schmidt, Henrik Nikolaj Blicher; Hattel, Jesper Henri

    2008-01-01

    , is investigated. The welding process is simulated in 2-dimensions with a sequentially coupled transient thermo-mechanical model using ANSYS. The numerical optimization problem is implemented in modeFRONTIER and solved using the Multi-Objective Genetic Algorithm (MOGA-II). An engineering-wise evaluation or ranking......In the present paper, numerical optimization of the process parameters, i.e. tool rotation speed and traverse speed, aiming minimization of the two conflicting objectives, i.e. the residual stresses and welding time, subjected to process-specific thermal constraints in friction stir welding...

  1. Analysis of Residual Stress for Narrow Gap Welding Using Finite Element Method

    Science.gov (United States)

    Lee, Choon Yeol; Hwang, Jae Keun; Bae, Joon Woo

    Reactor coolant loop (RCL) pipes circulating the heat generated in a nuclear power plant consist of so large diameter pipes that the installation of these pipes is one of the major construction processes. Conventionally, a shield metal arc welding (SMAW) process has been mainly used in RCL piping installations, which sometimes caused severe deformations, dislocation of main equipments and various other complications due to excessive heat input in welding processes. Hence, automation of the work of welding is required and narrow-gap welding (NGW) process is being reviewed for new nuclear power plants as an alternative method of welding. In this study, transient heat transfer and thermo-elastic-plastic analyses have been performed for the residual stress distribution on the narrow gap weldment of RCL by finite element method under various conditions including surface heat flux and temperature dependent thermo-physical properties.

  2. Microstructure and Residual Stress Distributions Under the Influence of Welding Speed in Friction Stir Welded 2024 Aluminum Alloy

    Science.gov (United States)

    Moghadam, Danial Ghahremani; Farhangdoost, Khalil; Nejad, Reza Masoudi

    2016-06-01

    Friction stir welding was conducted on 8-mm-thick plates made of AA2024-T351 aluminum alloy at tool traverse speeds between 8 and 31.5 mm/minutes and tool rotational speed between 400 and 800 rpm. Metallographic analyses and mechanical tests including hardness, tensile, residual stress, and fracture toughness tests were carried out to evaluate the microstructural and mechanical properties of the joints as a function of the process parameters. The finite element simulation of the FSW process was also performed using a thermal model. The hardness test results show that the increase in rotational speed or decrease in traverse speed of the tool would cause a decrease in weld zone hardness. The best tensile properties are obtained at rotational/traverse speed ratio between 20 and 32. Also, the longitudinal residual stress profiles were evaluated by employing X-ray diffraction method. The numerical and experimental results showed that the increase in a traverse or rotational speed would increase the residual stress of the weld zone. From the fracture toughness results, it was found that the welding process decreases the joints fracture toughness 18 to 49 pct with respect to the base metal.

  3. Effects of zonal heat treatment on residual stresses and mechanical properties of electron beam welded TC4 alloy plates

    Institute of Scientific and Technical Information of China (English)

    HU Mei-juan; LIU Jin-he

    2009-01-01

    Zonal heat treatment(ZHT) was conducted in situ to 14.5 mm-thick TC4 alloy plates by means of defocused electron beam after welding. The effects of ZHT on residual stresses, microstructures and mechanical properties of electron beam welded joints were investigated. Experimental results show residual stresses after welding are mostly relieved through ZHT, and the maximum values of longitudinal tensile stress and transverse compressive stress reduce by 76% and 65%, respectively. The tensile strength and ductility of welded joint after ZHT at slow scanning velocity are improved because of the reduction of residual stress and the microstructural changes of the base and weld metal. ZHT at fast scanning velocity is detrimental to the ductility of welded joint, which is resulted from insufficiently coarsened alpha phase in the fusion zone and the appearance of martensite in the base metal.

  4. Investigation of residual stresses in welded joints of heat-resistant magnesium alloy ML10 after electrodynamic treatment

    Directory of Open Access Journals (Sweden)

    L.M. Lobanov

    2016-06-01

    Full Text Available In repair of aircraft structures of magnesium alloy ML10, the argon arc non-consumable electrode welding is used. In this case, the residual welding stresses occur in repair welds, being one of the causes for reducing the service characteristics of the restored products. Residual stresses arise as a result of welding. Post-weld heat treatment is used to reduce the residual stresses. The heat treatment, which occurs after welding, increases the cost of repair. This leads to the search for alternative methods to control the stressed state of welded joints, one of which is electrodynamic treatment, which reduces the level of residual stresses in repair welds, and as a consequence, the cost of the welding repair in restoring aircraft structures. It was found from the results of experiments carried out, that the electrodynamic treatment allows reduces the initial level of stresses in welded joints, reaching 120 MPa, to 30 MPa, and at definite geometric characteristics of the specimens forming the field of compressive stresses, the values of which are equal to –50 MPa. It is shown that the optimum distance between the zones of treatment, being 5 mm, provides the guaranteed covering the zones of electrodynamic effect and, as a consequence, the maximum efficiency of the electric dynamic treatment.

  5. Measurement and modeling of residual stress in a welded Haynes[reg] 25 cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, C. [Div. of Eng. Mat., Department of Mech. Eng., Linkoeping University, 58183 Linkoeping (Sweden)]. E-mail: clarsson@cfl.rr.com; Holden, T.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bourke, M.A.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Stout, M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Teague, J. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lindgren, L.-E. [Div. Comp. Aided Design, Lulea University of Technology and Dalarna University, 97187 Lulea (Sweden)

    2005-06-15

    An experimental and simulation study of residual stresses was made in the vicinity of a gas tungsten arc weld, used to join a hemispherical end cap to a cylinder. The capped cylinder is used in a satellite application and was fabricated from a Co-based Haynes[reg] 25 alloy. The cylinder was 34.7 mm in outer diameter and 3.3 mm in thickness. The experimental measurements were made by neutron diffraction and the simulation used the implicit Marc finite element code. The experimental resolution was limited to approximately 3 mm parallel to the axis of the cylinder (the weld was 6 mm in the same direction) and comparison over the same volume of the finite element prediction showed general agreement. Subject to the limited spatial resolution, the largest experimentally measured tensile residual stress was 180 MPa, located at the middle of the weld. However, the predictions suggest that there are regions in the weld where average tensile residual stresses as much as 400 MPa exist. One qualitative disparity between the model and the experiments was that the measurement included a larger degree of asymmetry on either side of the weld than predicted by the model.

  6. 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.

  7. Thermo-mechanical Modeling for Residual Stresses of Friction Stir Welding of Dissimilar Alloys

    Directory of Open Access Journals (Sweden)

    ABDUL ARIF

    2013-06-01

    Full Text Available Friction stir welding is an advanced joining process that has been used for high production since 1996. FSW produces a weld that is strong than the base material because melting does not occur and joining takes place below the melting temperature of the material. FSW produces no fumes and can join aluminum alloys, magnesium, steels, copper and titanium. In this study, a thermo-mechanical model with improved potential is developed to study the formation of residual stress field in dissimilar materials. The model predictions were confirmed with experimental data obtained by Jamshidi et al. on dissimilar aluminum alloys AA6061 to AA5086. A commercial finite element software ANSYS® is used for simulation of friction stir welding. Longitudinal and transverse residual stresses are obtained when AA5086-O on the advancing side and AA6061- T6 on the retreating side after 15sec.

  8. Investigation and Analysis of Weld Induced Residual Stresses in Two Dissimilar Pipes by Finite Element Modeling

    Science.gov (United States)

    Nadimi, S.; Khoushehmehr, R. J.; Rohani, B.; Mostafapour, A.

    In the present study, Manual Metal Arc Welding (MMAW) of austenitic stainless steel to carbon steel were studied. The Schaeffler diagram were used in determining suitable filler metal for this process and then the finite element analysis of residual stresses in butt welding of two dissimilar pipes is performed with the commercial software ANSYS, which includes moving heat source, material deposit, temperature dependant material properties, metal plasticity and elasticity, transient heat transfer and mechanical analysis. The residual stresses distribution and magnitude in the hoop and axial directions in the inner and outer surfaces of two dissimilar pipes were obtained. Welding simulation considered as a sequentially coupled thermo-mechanical analysis and the element birth and death technique was employed for simulation of filler metal deposition.

  9. Finite Element Analysis of Modeling Residual Stress Distribution in All-position Duplex Stainless Steel Welded Pipe

    Institute of Scientific and Technical Information of China (English)

    Xiaojun JIN; Lixing HUO; Yufeng ZHANG; Bingren BAI; Xiaowei LI; Jun CAO

    2004-01-01

    On the basis of the thermal-elastic-plastic theory, a three-dimensional finite element numerical simulation is performed on the girth welded residual stresses of the duplex stainless steel pipe with ANSYS nonlinear finite element program for the first time. Three-dimensional FEM using mobile heat source for analysis transient temperature field and welding stress field in circumferential joint of pipes is founded. Distributions of axial and hoop residual stresses of the joint are investigated. The axial and the hoop residual stresses at the weld and weld vicinity on inner surface of pipes are tensile, and they are gradually transferred into compressive with the increase of the departure from the weld. The axial residual stresses at the weld and weld vicinity on outer surface of pipes is compressive while the hoop one is tensile. The distributions of residual stresses compared positive-circle with negative-circle show distinct symmetry. These results provide theoretical knowledge for the optimization of process and the control of welding residual stresses.

  10. Predicting welding residual stresses in a dissimilar metal girth welded pipe using 3D finite element model with a simplified heat source

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Dean, E-mail: deandeng@cqu.edu.c [College of Materials Science and Engineering, Chongqing University, Shazheng Street 174, Shapingba, Chongqing 400044 (China); Kiyoshima, Shoichi [Research Center of Computational Mechanics, Inc., Togoshi NI-Bldg., 1-7-1 Togoshi, Shinagawa-ku, Tokyo 142-0041 (Japan); Ogawa, Kazuo [Japan Nuclear Energy Safety Organization, TOKYU REIT Toranomon Bldg, 3-17-1, Toranomon, Minato-ku, Tokyo 105-0001 (Japan); Yanagida, Nobuyoshi [Hitachi Ltd. 1-1, Saiwa-cho 3-chome, Hitachi-shi, Ibaraki-ken 317-8511 (Japan); Saito, Koichi [Hitachi-GE Nuclear Energy, Ltd. 2-2, Omika-cho, 5-chome, Hitachi-shi, Ibaraki-ken 319-1221 (Japan)

    2011-01-15

    Research highlights: Welding residual stresses have asymmetrical distributions in the dissimilar metal pipe. Variable length heat source model can largely save computing time. Besides welding, other thermal processes also affect residual stresses. - Abstract: Dissimilar metal welds are commonly used in nuclear power plants to connect low alloy steel components and austenitic stainless steel piping systems. The integrity assessment and life estimation for such welded structures require consideration of residual stresses induced by manufacturing processes. Because the fabrication process of dissimilar metal weld joints is considerably complex, it is very difficult to accurately predict residual stresses. In this study, both numerical simulation technology and experimental method were used to investigate welding residual stress distribution in a dissimilar metal pipe joint with a medium diameter, which were performed by a multi-pass welding process. Firstly, an experimental mock-up was fabricated to measure the residual stress distributions on the inside and the outside surfaces. Then, a time-effective 3-D finite element model was developed to simulate welding residual stresses through using a simplified moving heat source. The simplified heat source method could complete the thermo-mechanical analysis in an acceptable time, and the simulation results generally matched the measured data near the weld zone. Through comparing the simulation results and the experimental measurements, we can infer that besides the multi-pass welding process other key manufacturing processes such as cladding, buttering and heat treatment should also be taken into account to accurately predict residual stresses in the whole range of the dissimilar metal pipe.

  11. Study of Welding Distortion and Residual Stress Considering Nonlinear Yield Stress Curves and Multi-constraint Equations

    Science.gov (United States)

    Rong, Youmin; Zhang, Guojun; Huang, Yu

    2016-10-01

    Inherent strain analysis has been successfully applied to predict welding deformations of large-scale structural components, while thermal-elastic-plastic finite element method is rarely used for its disadvantages of long calculation period and large storage space. In this paper, a hybrid model considering nonlinear yield stress curves and multi-constraint equations to thermal-elastic-plastic analysis is further proposed to predict welding distortions and residual stresses of large-scale structures. For welding T-joint structural steel S355JR by metal active gas welding, the published experiment results of temperature and displacement fields are applied to illustrate the credibility of the proposed integration model. By comparing numerical results of four different cases with the experiment results, it is verified that prediction precision of welding deformations and residual stresses is apparently improved considering the power-law hardening model, and computational time is also obviously shortened about 30.14% using multi-constraint equations. On the whole, the proposed hybrid method can be further used to precisely and efficiently predict welding deformations and residual stresses of large-scale structures.

  12. Microstructure, Hardness, and Residual Stress Distributions in T-Joint Weld of HSLA S500MC Steel

    Science.gov (United States)

    Frih, Intissar; Montay, Guillaume; Adragna, Pierre-Antoine

    2017-01-01

    This paper investigates the characterization of the microstructure, hardness, and residual stress distributions of MIG-welded high-strength low-alloy S500MC steel. The T-joint weld for 10-mm-thick plates was joined using a two passes MIG welding technology. The contour method was performed to measure longitudinal welding residual stress. The obtained results highlighted a good correlation between the metallurgical phase constituents and hardness distribution within the weld zones. In fact, the presence of bainite and smaller ferrite grain size in the weld-fusion zone might be the reason for the highest hardness measured in this region. A similar trend of the residual stress and hardness distributions was also obtained.

  13. Microstructure, Hardness, and Residual Stress Distributions in T-Joint Weld of HSLA S500MC Steel

    Science.gov (United States)

    Frih, Intissar; Montay, Guillaume; Adragna, Pierre-Antoine

    2017-03-01

    This paper investigates the characterization of the microstructure, hardness, and residual stress distributions of MIG-welded high-strength low-alloy S500MC steel. The T-joint weld for 10-mm-thick plates was joined using a two passes MIG welding technology. The contour method was performed to measure longitudinal welding residual stress. The obtained results highlighted a good correlation between the metallurgical phase constituents and hardness distribution within the weld zones. In fact, the presence of bainite and smaller ferrite grain size in the weld-fusion zone might be the reason for the highest hardness measured in this region. A similar trend of the residual stress and hardness distributions was also obtained.

  14. Analysis of welding-induced residual stresses with the ADINA system

    Energy Technology Data Exchange (ETDEWEB)

    Wilkening, W.W,; Snow, J.L.

    1993-12-01

    Welding-induced residual stresses analysis procedure (WIRSAP), based on ADINA system of nonlinear finite element software, is described and results of several WIRSAP analyses are discussed. Several 2D axisymmetric WIRSAP analyses were performed for pipe girth welds and for several multi-pass girth-like welds attaching small nozzles to large, thick-walled pressure vessels. The analytical methodology follows closely Rybicki et al, enhanced by several specialized modeling techniques available in ADINA. The element birth option is used to simulate the addition of weld metal, and the mixed pressure/ displacement element formulation is used, in conjunction with temperature-dependent bi-linear plasticity material model. Some of the welds analyzed involve backing rings, which were subsequently `machined off` via use of the element death option. The auto-time-stepping algorithm and matrix update iteration scheme are used in structural solutions. WIRSAP involves, a pass-by-pass analysis of uncoupled thermal and structural problems, but some analyses have been performed with an ``enveloping`` technique for grouping several weld passes together. The analyses are all 2D, but most are large problems and pose challenge to software and hardware. Operations are performed on a network of Silicon Graphics workstations, and ADINA and ADINA-T are executed on a 64 MW, eight-processor CRAY YIMP. Nominally 50 solution steps are utilized for each weld pass and weld joints involving as many as 31 individual weld passes analyzed on a pass-by-pass basis. Results from several WIRSAP analyses are discussed, and potential use of WIRSAP in a hypothetic attachment weld design optimization study is illustrated.

  15. Roller Burnishing - A Cold Working Tool to Reduce Weld Induced Residual Stress

    Energy Technology Data Exchange (ETDEWEB)

    John Martin

    2002-02-19

    The possibility of stress corrosion cracking (SCC) in regions of tensile residual stress introduced by weld deposited material has been a concern where environmental effects can reduce component life. Roller burnishing, a form of mechanical cold-working, has been considered as a means of providing for residual stress state improvements. This paper provides a computational evaluation of the roller burnishing process to address the permanent deformation needed to introduce a desirable residual stress state. The analysis uses a series of incrementally applied pressure loadings and finite element methodology to simulate the behavior of a roller burnishing tool. Various magnitudes of applied pressure loadings coupled with different size plates and boundary conditions are examined to assess the degree and depth of the residual compressive stress state after cold working. Both kinematic and isotropic hardening laws are evaluated.

  16. Analysis of Residual Stresses in Laser-Shock-Peened and Shot-Peened Marine Steel Welds

    Science.gov (United States)

    Ahmad, Bilal; Fitzpatrick, Michael E.

    2017-02-01

    Laser peening is now the preferred method of surface treatment in many applications. The magnitude and depth of the compressive residual stress induced by laser peening can be influenced strongly by the number of peen layers (the number of laser hits at each point) and by processing conditions including the use of a protective ablative layer. In this study, residual stresses have been characterized in laser and shot-peened marine butt welds with a particular focus at the fatigue crack initiation location at the weld toe. X-ray diffraction, synchrotron X-ray diffraction, incremental center-hole drilling, and the contour method were used for determination of residual stress. Results showed that the use of ablative tape increased the surface compressive stress, and the depth of compressive stress increased with an increase in number of peening layers. A key result is that variation of residual stress profile across laser peen spots was seen, and the residual stress magnitude varies between the center and edges of the spots.

  17. Repair weld induced residual stresses in thick-walled steel pressure vessels

    Energy Technology Data Exchange (ETDEWEB)

    Smith, G.C.; Holz, P.P.

    1978-06-01

    If a flaw requiring corrective action were to be found in an operating nuclear pressure vessel, there would be considerable safety and economic implications. Should such a flaw be found, one possible corrective action would be an in situ repair weld. A repair of this type would presumably involve grinding away material in a region encompassing the flaw and then filling the resulting cavity with weld metal. Thermal stress relieving under those conditions could lead to serious difficulties associated with thermal expansion and warpage and would therefore most likely be avoided. Such a departure from normal procedure raises questions relating to residual stresses and material toughness levels which would have to be assessed before a repair could be recommended or approved. The residual stress measurements reported are intended to provide baseline information to aid in an assessment should such a repair ever have to be seriously considered.

  18. 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)

  19. The Effect of Welding Residual Stress for Making Artificial Stress Corrosion Crack in the STS 304 Pipe

    Directory of Open Access Journals (Sweden)

    Jae-Seong Kim

    2015-01-01

    Full Text Available The stress corrosion crack is one of the fracture phenomena for the major structure components in nuclear power plant. During the operation of a power plant, stress corrosion cracks are initiated and grown especially in dissimilar weldment of primary loop components. In particular, stress corrosion crack usually occurs when the following three factors exist at the same time: susceptible material, corrosive environment, and tensile stress (residual stress included. Thus, residual stress becomes a critical factor for stress corrosion crack when it is difficult to improve the material corrosivity of the components and their environment under operating conditions. In this study, stress corrosion cracks were artificially produced on STS 304 pipe itself by control of welding residual stress. We used the instrumented indentation technique and 3D FEM analysis (using ANSYS 12 to evaluate the residual stress values in the GTAW area. We used the custom-made device for fabricating the stress corrosion crack in the inner STS 304 pipe wall. As the result of both FEM analysis and experiment, the stress corrosion crack was quickly generated and could be reproduced, and it could be controlled by welding residual stress.

  20. Investigation of Residual Stresses and Distortion in Welded Pipe-Flange Joint of Different Classes

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2012-10-01

    Full Text Available ABSTRACT: Pipe and flange joints are commonly used in petrochemical, nuclear and process industries. Commonly, welding is used to make these joints which produces residual stresses and distortions. These stresses have detrimental effects on the structural integrity and service performance of the welded pipe joints. The objective of this study is to investigate the residual stresses and distortions during Gas Metal Arc Welding of pipe of schedule 40, nominal diameter 200 mm with different ANSI flanges of class numbers 150, 300, 600, 900, 1500, and 2500. Welding parameters including: voltage, current and heat as inputs were selected based on the literature available. The behaviour of the flanges of different classes is also discussed. In addition, the finite element methodology presented, in this paper, can be helpful for developing welding procedures for a range of pipe flange welded joint sizes in order to control the residual stresses and deformations. This will lead to optimised performance during bolt up and operating conditions.ABSTRAK: Paip dan sambungan flan biasanya digunakan dalam industri petrokimia, nuklear dan proses. Kimpalan menghasilkan tegasan sisa dan herotan, yang memberikan kesan yang merbahaya ke atas integriti struktur dan prestasi servis sambungan kimpalan paip. Objektif kajian ini adalah untuk mengkaji tegasan sisa dan herotan ketika kimpalan arka logam gas paip berjadual 40, diameter nominal 200mm dengan flan ANSI yang berbeza kelas # 150, 300, 600, 900, 1500, dan 2500. Parameter kimpalan termasuklah; voltan, arus dan haba input yang dipilih berdasarkan literatur sediada. Kelakuan flan yang berbeza kelas telah dibincangkan. Kaedah elemen finit yang dibentangkan adalah berguna dalam membangunkan prosedur kimpalan bagi julat saiz kimpalan flan paip unutk mengawal tegasan sisa dan canggaan i.e. bagi mengoptimakan prestasi ketika bolt up dan sedang beroperasi.                                 

  1. Residual stress determination in a dissimilar weld overlay pipe by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Wanchuck, E-mail: chuckwoo@kaeri.re.kr [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Em, Vyacheslav [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Hubbard, Camden R. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Lee, Ho-Jin [Nuclear Materials Research Center, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Park, Kwang Soo [Corporate R and D Institute, Doosan Heavy Industries and Construction, Changwon 641-792 (Korea, Republic of)

    2011-10-15

    Highlights: {yields} Determined residual stress distribution in a dissimilar weld overlay pipe. {yields} Consists of a ferritic (SA508), austenitic (F316L) steels, Alloy 182 consumable. {yields} Measured significant compression (-600 MPa) near the inner wall of overlay. {yields} Validate integrity of the inner wall for the pressurized nozzle nuclear structure. - Abstract: Residual stresses were determined through the thickness of a dissimilar weld overlay pipe using neutron diffraction. The specimen has a complex joining structure consisting of a ferritic steel (SA508), austenitic steel (F316L), Ni-based consumable (Alloy 182), and overlay of Ni-base superalloy (Alloy 52M). It simulates pressurized nozzle components, which have been a critical issue under the severe crack condition of nuclear power reactors. Two neutron diffractometers with different spatial resolutions have been utilized on the identical specimen for comparison. The macroscopic 'stress-free' lattice spacing (d{sub o}) was also obtained from both using a 2-mm width comb-like coupon. The results show significant changes in residual stresses from tension (300-400 MPa) to compression (-600 MPa) through the thickness of the dissimilar weld overlay pipe specimen.

  2. A Comparison of Residual Stress Development in Inertia Friction Welded Fine Grain and Coarse Grain Nickel-Base Superalloy

    Science.gov (United States)

    Iqbal, N.; Rolph, J.; Moat, R.; Hughes, D.; Hofmann, M.; Kelleher, J.; Baxter, G.; Withers, P. J.; Preuss, M.

    2011-12-01

    The effect of the base material microstructure on the development of residual stresses across the weld line in inertia friction welds (IFWs) of high-strength nickel-base superalloy RR1000 was studied using neutron diffraction. A comparison was carried out between tubular IFW specimens generated from RR1000 heat treated below (fine grain (FG) structure) and above (coarse grain (CG) structure) the γ'-solvus. Residual stresses were mapped in the as-welded (AW) condition and, after a postweld heat treatment (PWHT), optimized for maximum alloy strength. The highest tensile stresses were generally found in the hoop direction at the weld line near the inner diameter of the tubular-shaped specimens. A comparison between the residual stresses generated in FG and CG RR1000 suggests that the starting microstructure has little influence on the maximum residual stresses generated in the weld even though different levels of energy must be input to achieve a successful weld in each case. The residual stresses in the postweld heat treated samples were about 35 pct less than for the AW condition. Despite the fact that the high-temperature properties of the two parent microstructures are different, no significant differences in terms of stress relief were found between the FG and CG RR1000 IFWs. Since the actual weld microstructures of FG and CG RR1000 inertia welds are very similar, the results suggest that it is the weld microstructure and its associated high-temperature properties rather than the parent material that affects the overall weld stress distribution and its subsequent stress relief.

  3. Measurement and prediction of residual stress in a bead-on-plate weld benchmark specimen

    Energy Technology Data Exchange (ETDEWEB)

    Ficquet, X.; Smith, D.J. [Department of Mechanical Engineering, University of Bristol, Queen' s Building, University Walk, Bristol BS8 1TR (United Kingdom); Truman, C.E. [Department of Mechanical Engineering, University of Bristol, Queen' s Building, University Walk, Bristol BS8 1TR (United Kingdom)], E-mail: c.e.truman@bristol.ac.uk; Kingston, E.J. [Veqter Ltd, University Gate East, Park Row, Bristol BS1 5UB (United Kingdom); Dennis, R.J. [Frazer-Nash Consultancy Limited, 1 Trinity Street, College Green, Bristol BS1 5TE (United Kingdom)

    2009-01-15

    This paper presents measurements and predictions of the residual stresses generated by laying a single weld bead on a flat, austenitic stainless steel plate. The residual stress field that is created is strongly three-dimensional and is considered representative of that found in a repair weld. Through-thickness measurements are made using the deep hole drilling technique, and near-surface measurements are made using incremental centre hole drilling. Measurements are compared to predictions at the same locations made using finite element analysis incorporating an advanced, non-linear kinematic hardening model. The work was conducted as part of an European round robin exercise, coordinated as part of the NeT network. Overall, there was broad agreement between measurements and predictions, but there were notable differences.

  4. Influence of Tacking Sequence on Residual Stress and Distortion of Single Sided Fillet Submerged Arc Welded Joint

    Institute of Scientific and Technical Information of China (English)

    Arpan Kumar Mondal; Pankaj Biswas; Swarup Bag

    2015-01-01

    Submerged arc welding (SAW) is advantageous for joining high thickness materials in large structure due to high material deposition rate. The non-uniform heating and cooling generates the thermal stresses and subsequently the residual stresses and distortion. The longitudinal and transverse residual stresses and angular distortion are generally measured in large panel structure of submerged arc welded fillet joints. Hence, the objective of this present work is to quantify the amount of residual stress and distortion in and around the weld joint due to positioning of stiffeners tack. The tacking sequence influences the level of residual stress and proper controlling of tacking sequences is required to minimize the stress. In present study, an elasto-plastic material behavior is considered to develop the thermo mechanical model which predicts the residual stress and angular distortion with varying tacking sequences. The simulated result reveals that the tacking sequence heavily influences the residual stress and deformation pattern of the single sided fillet joint. The finite element based numerical model is calibrated by comparing the experimental data from published literature. Henceforth, the angular distortions are measured from an in-house developed experimental set-up. A fair agreement between the predicted and experimental results indicates the robustness of the developed numerical model. However, the most significant conclusion from present study states that tack weld position should be placed opposite to the fillet weld side to minimize the residual stress.

  5. Neutron-diffraction measurement of residual stresses in Al-Cu cold-cut welding

    CERN Document Server

    Fiori, F

    2002-01-01

    Usually, when it is necessary to join different materials with a large difference in their melting points, welding should be avoided. To overcome this problem we designed and built a device to obtain cold-cut welding, which is able to strongly decrease oxidation problems of the surfaces to be welded. Thanks to this device it is possible to achieve good joining between different pairs of materials (Al-Ti, Cu-Al, Cu-Al alloys) without reaching the material melting point. The mechanical and microstructural characterisation of the joining and the validation of its quality were obtained using several experimental methods. In particular, in this work neutron-diffraction experiments for the evaluation of residual stresses in Cu-Al junctions are described, carried out at the G5.2 diffractometer of LLB, Saclay. Neutron-diffraction results are presented and related to other experimental tests such as microstructural characterisation (through optical and scanning electron microscopy) and mechanical characterisation (ten...

  6. Evolution of microstructure and residual stress under various vibration modes in 304 stainless steel welds.

    Science.gov (United States)

    Hsieh, Chih-Chun; Wang, Peng-Shuen; Wang, Jia-Siang; Wu, Weite

    2014-01-01

    Simultaneous vibration welding of 304 stainless steel was carried out with an eccentric circulating vibrator and a magnetic telescopic vibrator at subresonant (362 Hz and 59.3 Hz) and resonant (376 Hz and 60.9 Hz) frequencies. The experimental results indicate that the temperature gradient can be increased, accelerating nucleation and causing grain refinement during this process. During simultaneous vibration welding primary δ -ferrite can be refined and the morphologies of retained δ-ferrite become discontinuous so that δ-ferrite contents decrease. The smallest content of δ-ferrite (5.5%) occurred using the eccentric circulating vibrator. The diffraction intensities decreased and the FWHM widened with both vibration and no vibration. A residual stress can obviously be increased, producing an excellent effect on stress relief at a resonant frequency. The stress relief effect with an eccentric circulating vibrator was better than that obtained using a magnetic telescopic vibrator.

  7. Finite Element Modeling and Validation of Residual Stresses in 304 L Girth Welds

    Energy Technology Data Exchange (ETDEWEB)

    Dike, J.J.; Ortega, A.R.; Cadden, C.H.; Rangaswamy, P. Brown, D.

    1998-06-01

    Three dimensional finite element simulations of thermal and mechanical response of a 304 L stainless steel pipe subjected to a circumferential autogenous gas tungsten arc weld were used to predict residual stresses in the pipe. Energy is input into the thermal model using a volumetric heat source. Temperature histories from the thermal analysis are used as loads in the mechanical analyses. In the mechanical analyses, a state variable constitutive model was used to describe the material behavior. The model accounts for strain rate, temperature, and load path histories. The predicted stresses are compared with x-ray diffraction determinations of residual stress in the hoop and circumferential directions on the outside surface of the pipe. Calculated stress profiles fell within the measured data. Reasons for observed scatter in measured stresses are discussed.

  8. Measurement of residual stresses in the dissimilar metal weld joint of a safe-end nozzle mock-up

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Kazuo (Japan Nuclear Energy Safety Organisation, Tokyo (Japan)); Kingston, E.; Chidwick, L. (VEQTER Ltd., Bristol (United Kingdom)); Smith, D. (Univ. of Bristol (United Kingdom))

    2009-07-01

    Knowledge of the origin, magnitude and distribution of residual stresses generated during the manufacture of nuclear power plants is of vital importance to their structural integrity assessment. The overall aim of this work was to measure welding residual stresses in components prone to primary water stress corrosion cracking in nuclear reactor pressure vessels. This paper describes the on-site application of the Deep-Hole Drilling (DHD) technique to measure the through-thickness residual stress distributions through a safe-end nozzle component containing a dissimilar metal weld joint at different stages of manufacture

  9. A Study on the Residual Stress Improvement of PWSCC(Primary Water Stress Corrosion Cracking) in DMW(Dissimilar Metal Weld)

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sung Sik; Kim, Seok Hun; Lee, Seung Gun [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Park, Heung Bae [KEPCO Engineering and Construction Company, Daejeon (Korea, Republic of)

    2010-10-15

    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

  10. Validating a Model for Welding Induced Residual Stress Using High-Energy X-ray Diffraction

    Science.gov (United States)

    Mach, J. C.; Budrow, C. J.; Pagan, D. C.; Ruff, J. P. C.; Park, J.-S.; Okasinski, J.; Beaudoin, A. J.; Miller, M. P.

    2017-03-01

    Integrated computational materials engineering (ICME) provides a pathway to advance performance in structures through the use of physically-based models to better understand how manufacturing processes influence product performance. As one particular challenge, consider that residual stresses induced in fabrication are pervasive and directly impact the life of structures. For ICME to be an effective strategy, it is essential that predictive capability be developed in conjunction with critical experiments. In the present work, simulation results from a multi-physics model for gas metal arc welding are evaluated through x-ray diffraction using synchrotron radiation. A test component was designed with intent to develop significant gradients in residual stress, be representative of real-world engineering application, yet remain tractable for finely spaced strain measurements with positioning equipment available at synchrotron facilities. The experimental validation lends confidence to model predictions, facilitating the explicit consideration of residual stress distribution in prediction of fatigue life.

  11. Validating a Model for Welding Induced Residual Stress Using High-Energy X-ray Diffraction

    Science.gov (United States)

    Mach, J. C.; Budrow, C. J.; Pagan, D. C.; Ruff, J. P. C.; Park, J.-S.; Okasinski, J.; Beaudoin, A. J.; Miller, M. P.

    2017-05-01

    Integrated computational materials engineering (ICME) provides a pathway to advance performance in structures through the use of physically-based models to better understand how manufacturing processes influence product performance. As one particular challenge, consider that residual stresses induced in fabrication are pervasive and directly impact the life of structures. For ICME to be an effective strategy, it is essential that predictive capability be developed in conjunction with critical experiments. In the present work, simulation results from a multi-physics model for gas metal arc welding are evaluated through x-ray diffraction using synchrotron radiation. A test component was designed with intent to develop significant gradients in residual stress, be representative of real-world engineering application, yet remain tractable for finely spaced strain measurements with positioning equipment available at synchrotron facilities. The experimental validation lends confidence to model predictions, facilitating the explicit consideration of residual stress distribution in prediction of fatigue life.

  12. High-Temperature Deformation Constitutive Law for Dissimilar Weld Residual Stress Modeling: Effect of Thermal Load on Strain Hardening

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xinghua [ORNL; Wang, Yanli [ORNL; Crooker, Paul [Electric Power Research Institute (EPRI); Feng, Zhili [ORNL

    2015-01-01

    Weld residual stress is one of the primary driving forces for primary water stress corrosion cracking in dissimilar metal welds (DMWs). To mitigate tensile residual stress in DMWs, it is critical to understand residual stress distribution by modeling techniques. Recent studies have shown that weld residual stress prediction using today s DMW residual stress models strongly depends on the strain-hardening constitutive model chosen. The commonly used strain-hardening models (isotropic, kinematic, and mixed) are all time-independent and inadequate to account for the time-dependent (viscous) plastic deformation at the elevated temperatures experienced during welding. For materials with profound strain-hardening, such as stainless steels and nickel-based alloys that are widely used in nuclear reactor and piping systems, the equivalent plastic strain the determinate factor of the flow stress can be highly dependent on the recovery and recrystallization processes. These processes are in turn a strong function of temperature, time, and deformation rate. Recently, the authors proposed a new temperature- and time-dependent strain-hardening constitutive model: the dynamic strain-hardening constitutive model. The application of such a model has resulted in improved weld residual stress prediction compared to the residual stress measurement results from the contour and deep-hole drilling methods. In this study, the dynamic strain-hardening behavior of Type 304 stainless steel and Alloy 82 used in pressure vessel nozzle DMWs is experimentally determined. The kinetics of the recovery and recrystallization of flow stress are derived from experiments, resulting in a semi-empirical equation as a function of pre-strain, time, and temperature that can be used for weld residual stress modeling. The method used in this work also provides an approach to study the kinetics of recovery and recrystallization of other materials with significant strain-hardening.

  13. Final Report: Characterization of Canister Mockup Weld Residual Stresses

    Energy Technology Data Exchange (ETDEWEB)

    Enos, David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bryan, Charles R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-12-01

    Stress corrosion cracking (SCC) of interim storage containers has been indicated as a high priority data gap by the Department of Energy (DOE) (Hanson et al., 2012), the Electric Power Research Institute (EPRI, 2011), the Nuclear Waste Technical Review Board (NWTRB, 2010a), and the Nuclear Regulatory Commission (NRC, 2012a, 2012b). Uncertainties exist in terms of the environmental conditions that prevail on the surface of the storage containers, the stress state within the container walls associated both with weldments as well as within the base metal itself, and the electrochemical properties of the storage containers themselves. The goal of the work described in this document is to determine the stress states that exists at various locations within a typical storage canister by evaluating the properties of a full-diameter cylindrical mockup of an interim storage canister. This mockup has been produced using the same manufacturing procedures as the majority of the fielded spent nuclear fuel interim storage canisters. This document describes the design and procurement of the mockup and the characterization of the stress state associated with various portions of the container. It also describes the cutting of the mockup into sections for further analyses, and a discussion of the potential impact of the results from the stress characterization effort.

  14. Possibility of Inducing Compressive Residual Stresses in Welded Joints of SS400 Steels

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Since the welded constructions produce easily stress corrosion cracking (SCC) or fatigue disruption in corrosive medium or under ripple load, two methods inducing compressive stress on structural surfaces by anti-welding-heating treatment (AWHT) and explosion treatment (ET) are presented. The results show that they are good ways to resisting SCC on the welded SS400 steel or other components.

  15. 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

  16. Influence of the microstructural changes and induced residual stresses on tensile properties of wrought magnesium alloy friction stir welds

    Energy Technology Data Exchange (ETDEWEB)

    Commin, Loreleie, E-mail: lorelei.commin@kit.edu [LMPF, Arts et Metiers ParisTech, rue St Dominique, 51000 Chalons en Champagne (France); Dumont, Myriam [Aix-Marseille Universite, CNRS, IM2NP (UMR 6242), Faculte St-Jerome, Case 261, Av. Escadrille Normandie-Niemen, 13 397 Marseille Cedex 20 (France); Rotinat, Rene; Pierron, Fabrice [LMPF, Arts et Metiers ParisTech, rue St Dominique, 51000 Chalons en Champagne (France); Masse, Jean-Eric; Barrallier, Laurent [MecaSurf, Arts et Metiers ParisTech, 2 cours des Arts et Metiers, 13100 Aix en Provence (France)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Study of AZ31 FSW mechanical behaviour. Black-Right-Pointing-Pointer Early yielding occurs in the TMAZ, the nugget and base metal zones undergo almost no plastic strains. Black-Right-Pointing-Pointer Texture gradient in the TMAZ localises the deformations in this area. Black-Right-Pointing-Pointer 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.

  17. Studies of residual stress measurement and analysis techniques for a PWR dissimilar weld joint

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Naoki, E-mail: naoki2_ogawa@mhi.co.jp [Mitsubishi Heavy Industries, Ltd., 2-1-1, Shinhama, Arai-cho, Takasago 676-8686 (Japan); Muroya, Itaru; Iwamoto, Youichi; Ohta, Takahiro; Ochi, Mayumi; Hojo, Kiminobu [Mitsubishi Heavy Industries, Ltd., 2-1-1, Shinhama, Arai-cho, Takasago 676-8686 (Japan); Ogawa, Kazuo [Japan Nuclear Energy Safety Organization, 3-17-1, Toranomon, Minato-ku, Tokyo 105-0001 (Japan)

    2012-02-15

    For evaluation of the PWSCC crack propagation behavior, a test model was produced using the same fabrication process of Japanese PWR plants and the stress distribution change was measured during a fabrication process such as a hydrostatic test, welding a main coolant pipe to the stainless steel safe end and an operation condition test. For confirmation of validity of the numerical estimation method of the stress distribution, FE analysis was performed to calculate the stress distributions for each fabrication process. From the validation procedure, a standard residual stress evaluation method was established. Furthermore for consideration of characteristics of PWSCC's propagation behavior of the dissimilar welding joint of the safe end nozzles, the influence coefficients at the deepest point for the stress intensity factors of axial cracks with large aspect ratio a/c (crack depth/half of surface crack length) was prepared. The crack shape was assumed a rectangular shape and the stress intensity factors at the deepest point of the crack were calculated with change of crack depth using FE analysis. By using these stress distribution and influence coefficients, a behavior of a PWSCC crack propagation at the safe end nozzles can be estimated easily and rationally.

  18. Investigation of effect of post weld heat treatment conditions on residual stress for ITER blanket shield blocks

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hun-Chea, E-mail: hcjung@nfri.re.kr [ITER Korea, National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, Sa-Woong [ITER Korea, National Fusion Research Institute, Daejeon (Korea, Republic of); Lee, Yun-Hee [Division of Convergence Technology, Korea Research Institute of Standard and Science (KRISS), Daejeon (Korea, Republic of); Baek, Seung-Wook [Division of Industrial Metrology, Korea Research Institute of Standard and Science (KRISS), Daejeon (Korea, Republic of); Ha, Min-Su; Shim, Hee-Jin [ITER Korea, National Fusion Research Institute, Daejeon (Korea, Republic of)

    2016-11-01

    Highlights: • PWHT for ITER blanket shield block should be performed for dimensional stability. • Investigation of the effect of PWHT conditions on properties was performed. • Instrumented indentation method for evaluation of properties was used. • Residual stress and hardness decreased with increasing PWHT temperature. • Optimization of PWHT conditions would be needed for satisfaction of requirement. - Abstract: The blanket shield block (SB) shall be required the tight tolerance because SB interfaces with many components, such as flexible support keypads, First Wall (FW) support contact surfaces, FW central bolt, electrical strap contact surfaces and attachment inserts for both FW and Vacuum Vessel (VV). In order to fulfil the tight tolerance requirement, stress relieving shall be performed for dimensional stability after cover welding operation. In this paper, effect of Post Weld Heat Treatment (PWHT) conditions, temperature and holding time, was investigated on the residual stress and hardness. The 316L Stainless Steel (SS) was prepared and welded by manual TIG welding by using filler material with 2.4 mm of diameter. Welded 316L SS plate was machined to prepare the specimen for PWHT. PWHT was implemented at 250, 300, 400 °C for 2 and 3 h (400 °C only) and residual stress after relaxation were determined. The evaluation of residual stress and hardness for each specimen was carried out by instrumented indentation technique. The residual stress and hardness were decreased with increasing the heat treatment temperature and holding time.

  19. Local Cooling during Welding: Prediction and Control of Residual Stresses and Buckling Distortion

    NARCIS (Netherlands)

    Van der Aa, E.M.

    2007-01-01

    One of the major problems during welding of thin plate structures is the occurrence of buckling distortion. This type of distortion is caused by the formation of compressive welding stresses; when these stresses exceed a certain critical stress level, the structure will buckle. Most methods for elim

  20. Residual stress in a laser welded EUROFER blanket module assembly using non-destructive neutron diffraction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, D.J., E-mail: d.hughes@warwick.ac.uk [WMG, University of Warwick, Coventry CV4 7AL (United Kingdom); Koukovini-Platia, E. [CERN, CH-1211 Geneva 23 (Switzerland); Heeley, E.L. [Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    2014-02-15

    Highlights: • Residual stresses were determined in a welded EUROFER blanket assembly with integrated cooling channels. • Good agreement was seen between experimentally determined and predicted stresses. • We show that microstructure changes that occur in EUROFER steels during welding must be considered for residual stress determination. • An experimental route is proposed for validation of predicted stresses in reactor components using non-destructive diffraction techniques. - Abstract: Whilst the structural integrity and lifetime considerations in welded joints for blanket modules can be predicted using finite element software, it is essential to prove the validity of these simulations. This paper provides detailed analysis for the first time, of the residual stress state in a laser-welded sample with integral cooling channels. State-of-the-art non-destructive neutron diffraction was employed to determine the triaxial stress state and to understand microstructural changes around the heat affected zone. Synchrotron X-ray diffraction was used to probe the variation of strain-free lattice reference parameter around the weld zone allowing correction of the neutron measurements. This paper details an important experimental route to validation of predicted stresses in complex safety-critical reactor components for future applications.

  1. Eliminating welding residual stress by laser shock%激光冲击消除焊接残余应力

    Institute of Scientific and Technical Information of China (English)

    王学德; 胡雅骥; 王路成; 张东方

    2012-01-01

    The different viewpoints of welding residual stress were analyzed and the feasibility of erasing the welding residual stress by laser shock was discussed. Nanosecond pulse and 1000MW laser irradiation on the materials could induce the high pres-sure plasma shock wave and generate the plastic deformation, thus it could effectively eliminate welding residual tensile stress. The experiments of 12Cr2Ni4A steel welding joints processed with different welding materials and methods under laser shock pro-cessing (LSP) were designed, and conducted through four different welding statuses. Results showed that laser shock could erase the welding residual tensile stress caused by argon arc welding and plasma welding, and also could improve the distribution of force on the surface of welding joints. Using NAK80 welding material and plasma welding, the compression stress reached to 848MPa, which led to a sharp increase of mechanical properties of the weld joint.%对现有焊接残余应力的理论进行分析,讨论激光冲击处理消除焊接残余应力的可行性,认为短脉冲高峰值功率密度的激光冲击焊接接头产生的等离子体冲击波,可使焊接接头表面产生塑性应变,能有效消除焊接残余拉应力.文章设计了激光冲击强化12Cr2Ni4A钢焊接接头试验,通过选择不同焊接材料和焊接方式,设计了4种焊接状态,分别进行激光冲击强化.试验结果表明,激光冲击强化均能肖除氩弧焊和等离子焊等焊接方式的焊接残余拉应力,改善焊接接头表面的力学分布,在选用NAK80焊材和等离子体焊方式时,形成的残余压应力幅值高达884MPa,极大提升了焊接接头的力学性能.

  2. Modelling residual stresses in friction stir welding of Al alloys - a review of possibilities and future trends

    DEFF Research Database (Denmark)

    Hattel, Jesper Henri; Sonne, Mads Rostgaard; Tutum, Cem C.

    2015-01-01

    Residual stresses are very important in any joining process of materials since they act as pre-stresses in the loading situation of the joint, thereby affecting the final mechanical performance of the component. This is also the case for friction stir welding (FSW) which is a complex solid-state ...

  3. Development of methodology for measurements of residual stresses in welded joint based on displacement of points in a coordinated table

    Directory of Open Access Journals (Sweden)

    Aníbal Veras Siqueira Filho

    2013-04-01

    Full Text Available Residual stresses in a welded joint of ASTM A131 grade AH32 steel was measured either by the X-ray diffraction or by displacements of referenced points measured on a coordinate measuring machine before and after heat treatment. For all tests, the welding was performed with Shielded Metal Arc Welding, vertical-up position, by a certified welder. After welding, some specimens were subjected to marking, made through small holes evenly spaced and mapped on a coordinate measuring machine. After labeling, the samples were subjected to heat treatment at temperatures nearby recrystallization. After heat treatment, the samples were subjected to new measurements by coordinate measuring machine to evaluate the displacements of the points produced by the recrystallization. In parallel, residual stress measurements were made by XRD for validation of this new methodology. The results obtained either by X-ray or by coordinate measuring machine showed a good correlation between the two measurement methodologies employed.

  4. Problems in using a comb sample as a stress-free reference for the determination of welding residual stress by diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Ganguly, S.; Edwards, L. [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Fitzpatrick, M.E., E-mail: m.e.fitzpatrick@open.ac.uk [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    2011-01-25

    Research highlights: {yields} Comb samples used as reference samples in diffraction stress measurements on welds can retain significant macro-residual stress. {yields} Measurements of the retained residual stress have been made in a comb sample extracted from a VPPA-welded aluminium plate. {yields} A method is presented for the correction of the reference lattice parameter in the presence of retained residual stress. - Abstract: Precise measurement of a stress-free reference lattice parameter is vital in the determination of residual stress by diffraction techniques using {theta}/2{theta}-based analyses. For the evaluation of the residual strain profile in fusion-welded material, it is particularly important to correct the measured strain point-by-point by a stress-free reference for each spatial location across the weld. This is to take into account the compositional and microstructural variation across the weld caused by the thermal cycle of welding, as local changes in solute content of the parent alloy cause changes in the stress-free lattice parameter. Although ideally such measurements should be obtained from small cubes machined from the weld, the use of a comb sample has previously been proposed as a macro-stress-free reference, with the assumption that each finger of the comb is of insufficient dimension to hold a macro-stress field. This paper presents an approach towards analysis of the stress-free reference values using a comb sample extracted from a variable polarity plasma arc (VPPA) welded plate. It is shown that there is inter-granular stress and retained macro-stress within the comb teeth, and an experimental approach to deal with the problem is proposed.

  5. 3-D FINITE ELEMENT ANALYSIS OF THE EFFECT OF WELDING RESIDUAL STRESS ON HYDROGEN DIFFUSION IN HYDROGEN CONTAINED ENVIRONMENT

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The hydrogen distribution of 16MnR steel weldment in hydrogen contained environment was calculated using the finite element method (FEM). The effect of welding residual stress on hydrogen diffusion has been discussed using a 3-D sequential coupling finite element analysis procedure complied by Abaqus code. The hydrogen diffusion coefficient in weld metal, the heat affected zone (HAZ), and the base metal of the 16MnR steel weldment were measured using the electrochemical permeation technique. The hydrogen diffusion without the effect of stress was also calculated and compared. Owing to the existence of welding residual stress, the hydrogen concentration was obviously increased and the hydrogen would diffuse and accumulate in the higher stress region.

  6. Effect of strain hardening and strain softening on welding distortion and residual stress of A7N01-T4 aluminum alloy by simulation analysis

    Institute of Scientific and Technical Information of China (English)

    YAN De-jun; LIU Xue-song; LI Jun; YANG Jian-guo; FANG Hong-yuan

    2010-01-01

    The effect of strain hardening and strain softening behavior of flow stress changing with temperature on welding residual stress,plastic strain and welding distortion of A7N01-T4 aluminum alloy was studied by finite simulation method.The simulation results show that the weld seam undergoes strain hardening in the temperature range of 180-250℃,however,it exhibits strain softening at temperature above 250℃ during welding heating and cooling process.As a result,the strain hardening and strain softening effects counteract each other,introducing slightly influence on the welding residual stress,residual plastic strain and distortion.The welding longitudinal residual stress was determined by ultrasonic stress measurement method for the flat plates of A7N01-T4 aluminum alloy.The simulation results are well accordant with test ones.

  7. Residual Stresses and Tensile Properties of Friction Stir Welded AZ31B-H24 Magnesium Alloy in Lap Configuration

    Science.gov (United States)

    Naik, Bhukya Srinivasa; Cao, Xinjin; Wanjara, Priti; Friedman, Jacob; Chen, Daolun

    2015-08-01

    AZ31B-H24 Mg alloy sheets with a thickness of 2 mm were friction stir welded in lap configuration using two tool rotational rates of 1000 and 1500 rpm and two welding speeds of 10 and 20 mm/s. The residual stresses in the longitudinal and transverse directions of the weldments were determined using X-ray diffraction. The shear tensile behavior of the lap joints was evaluated at low [233 K (-40 °C)], room [298 K (25 °C)], and elevated [453 K (180 °C)] temperatures. The failure load was highest for the lower heat input condition that was obtained at a tool rotational rate of 1000 rpm and a welding speed of 20 mm/s for all the test temperatures, due to the smaller hooking height, larger effective sheet thickness, and lower tensile residual stresses, as compared to the other two welding conditions that were conducted at a higher tool rotational rate or lower welding speed. The lap joints usually fractured on the advancing side of the top sheet near the interface between the thermo-mechanically affected zone and the stir zone. Elevated temperature testing of the weld assembled at a tool rotational rate of 1000 rpm and a welding speed of 20 mm/s led to the failure along the sheet interface in shear fracture mode due to the high integrity of the joint that exhibited large plastic deformation and higher total energy absorption.

  8. Measurement of residual stresses in a multi-pass low alloy ferritic steel weld using X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, E.J.; Exworthy, L.F.; Flewitt, P.E.J. [Magnox Generation, Berkeley (United Kingdom); Hallam, K. [Interface Analysis Centre, Univ. of Bristol (United Kingdom); Bell, W. [Mitsui Babcock Energy Ltd, Renfrew (United Kingdom)

    2000-07-01

    A trial part through-section excavation manual metal arc repair weld, designed with a view to minimising residual stresses, was prepared by using a critical combination of weld metal strength, bead size and deposition pattern. The repair was in a low alloy ferritic CrMoV steel plate, and the weldment was made using a lower strength C-Mn steel weld metal. Residual stresses have been measured to a high spatial resolution, 1.5 mm, across the weldment using the X-ray diffraction technique with Cr K{alpha} X-radiation. Peak tensile stresses have been identified in the heat affected zone in the parent plate adjacent to the weld metal. Further measurements have been made using the rosette strain gauge centre hole relaxation and deep hole drilling techniques. Results from the experimental techniques are compared and the measured residual stress profiles are discussed with respect to the predictions of a finite element model for this particular multi-pass repair weld. (orig.)

  9. 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.

  10. Status report. Characterization of Weld Residual Stresses on a Full-Diameter SNF Interim Storage Canister Mockup.

    Energy Technology Data Exchange (ETDEWEB)

    Enos, David [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Bryan, Charles R. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    This report documents the mockup specifications and manufacturing processes; the initial cutting of the mockup into three cylindrical pieces for testing and the measured strain changes that occurred during the cutting process; and the planned weld residual stress characterization activities and the status of those activities.

  11. Numerical sensitivity analysis of welding-induced residual stress depending on variations in continuous cooling transformation behavior

    Science.gov (United States)

    Heinze, C.; Schwenk, C.; Rethmeier, M.; Caron, J.

    2011-06-01

    The usage of continuous cooling transformation (CCT) diagrams in numerical welding simulations is state of the art. Nevertheless, specifications provide limits in chemical composition of materials which result in different CCT behavior and CCT diagrams, respectively. Therefore, it is necessary to analyze the influence of variations in CCT diagrams on the developing residual stresses. In the present paper, four CCT diagrams and their effect on numerical calculation of residual stresses are investigated for the widely used structural steel S355J2 + N welded by the gas metal arc welding (GMAW) process. Rather than performing an arbitrary adjustment of CCT behavior, four justifiable data sets were used as input to the numerical calculation: data available in the Sysweld database, experimental data acquired through Gleeble dilatometry tests, and TTT/CCT predictions calculated from the JMatPro and Edison Welding Institute (EWI) Virtual Joining Portal software. The performed numerical analyses resulted in noticeable deviations in residual stresses considering the different CCT diagrams. Furthermore, possibilities to improve the prediction of distortions and residual stress based on CCT behavior are discussed.

  12. On Residual Stresses in Resistance Spot-Welded Aluminum Alloy 6061-T6: Experimental and Numerical Analysis

    Science.gov (United States)

    Afshari, D.; Sedighi, M.; Karimi, M. R.; Barsoum, Z.

    2013-12-01

    In this study, an electro-thermal-structural-coupled finite element (FE) model and x-ray diffraction residual stress measurements have been utilized to analyze distribution of residual stresses in an aluminum alloy 6061-T6 resistance spot-welded joint with 2-mm-thickness sheet. Increasing the aluminum sheet thickness to more than 1 mm leads to creating difficulty in spot-welding process and increases the complexity of the FE model. The electrical and thermal contact conductances, as mandatory factors are applied in contact areas of electrode-workpiece and workpiece-workpiece to resolve the complexity of the FE model. The physical and mechanical properties of the material are defined as thermal dependent to improve the accuracy of the model. Furthermore, the electrodes are removed after the holding cycle using the birth-and-death elements method. The results have a good agreement with experimental data obtained from x-ray diffraction residual stress measurements. However, the highest internal tensile residual stress occurs in the center of the nugget zone and decreases toward nugget edge; surface residual stress increases toward the edge of the welding zone and afterward, the area decreases slightly.

  13. Phase Transformation and Residual Stress in a Laser Beam Spot-Welded TiAl-Based Alloy

    Science.gov (United States)

    Liu, Jie; Staron, Peter; Riekehr, Stefan; Stark, Andreas; Schell, Norbert; Huber, Norbert; Schreyer, Andreas; Müller, Martin; Kashaev, Nikolai

    2016-12-01

    The microstructure, chemical composition, residual stress, and lattice parameter evolution of the welding zone (WZ) and heat-affected zone (HAZ) of a laser-beam-welded TiAl-based alloy were investigated. It was found that both α 2 and γ phases remain highly restrained in the WZ edge, and the stresses are relieved in the HAZ. A grain refinement mechanism is proposed, which works by heating the material to the β or α + β phase field for a short time. The lamellar colonies are refined by the Nb-enriched segregations.

  14. Residual stress in a laser welded EUROFER blanket module assembly using non-destructive neutron diffraction techniques

    CERN Document Server

    Hughes, D J; Heeley, E L

    2014-01-01

    Whilst the structural integrity and lifetime considerations in welded joints for blanket modules can be predicted using finite element software, it is essential to prove the validity of these simulations. This paper provides detailed analysis for the first time, of the residual stress state in a laser-welded sample with integral cooling channels. State-of-the-art non-destructive neutron diffraction was employed to determine the triaxial stress state and to understand microstructural changes around the heat affected zone. Synchrotron X-ray diffraction was used to probe the variation of strain-free lattice reference parameter around the weld zone allowing correction of the neutron measurements. This paper details an important experimental route to validation of predicted stresses in complex safety-critical reactor components for future applications.

  15. Effects of Geometry of Reactor Pressure Vessel Upper Head Control Rod Drive Mechanism Penetration Nozzles on J-Groove Weld Residual Stress

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ju Hee; Kim, Yun Jae; Bae, Hong Yeol [Korea University, Seoul (Korea, Republic of); and others

    2011-10-15

    In pressurized water reactors (PWRs), the reactor pressure vessel (RPV) upper head contains numerous control rod drive mechanism (CRDM) nozzles. In the last 10 years, the incidences of cracking in alloy 600 CRDM nozzles and their associated welds has increased significantly. Several axial and circumferential cracks have been found in CRDM nozzles in European PWRs and U.S. nuclear power plants. These cracks are caused by primary water stress corrosion cracking (PWSCC) and have been shown to be driven by welding residual stresses and operational stresses in the weld region. Therefore, detailed finite-element (FE) simulations for the Korea Nuclear Reactor Pressure Vessel have been conducted in order to predict the magnitudes of the weld residual stresses in the tube materials. In particular, the weld residual stress results are compared in terms for nozzle location, geometry factor ro/t, geometry of fillet, and adjacent nozzle.

  16. 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.

  17. Effect of transformation on residual stress in welding. Part 5. ; Stress releasement by transformation superplasticity. Sohentai ga yosetsu zanryu oryoku ni oyobosu eikyo. 5. ; Hentai chososei ni yoru oryoku kanwa

    Energy Technology Data Exchange (ETDEWEB)

    Murata, H. (Yokogawa Medical System Ltd., Tokyo (Japan)); Kato, N. (Tokyo Inst. of Technology, Tokyo (Japan)); Tamura, H. (Nihon Univ., Tokyo (Japan))

    1993-11-05

    The residual stress and angular deformation occurred in welding are the important factors for the welding design. In the previous report, by measuring the welding angular deformation caused by the welding rod prepared experimentally with the various transformation temperatures, it was shown that the materials, which could transform at a low temperature, have been effective to restrain the welding deformation. In addition, also the elongation and stress variation in transformation after welding have been examined in detail, and consequently it has been shown quantitatively, that not only the transformation expansion, but also the transformation superplasticity have acted effectively for the stress relaxation during transformation depending on the condition. In this report, the same as in the previous report, the welding with the multilayers and multi-passes has been performed by using the welding rod prepared experimentally and of Fe-Ni-Cr system, which could transform at a low temperature and had a high stress releasement effect, and then the effect of phase transformation on the welding residual stress has been investigated. As a result, the phase transformation had a tight relation with the welding residual stress, and furthermore the compression stress has been observed on the welding metal depending on the transformation temperature. In addition, it was found that in the welding metal, the compression stress has occurred, the tensile stress has remained directly under it, and it has been connected with a peak part of the tension, and has been redistributed. 18 refs., 8 figs., 1 tab.

  18. Prediction of the Residual Welding Stress in 2.25Cr-1Mo Steel by Taking into Account the Effect of the Solid-State Phase Transformations

    Institute of Scientific and Technical Information of China (English)

    Dean DENG; Yangang TONG; Ninshu MA; Hidekazu MURAKAWA

    2013-01-01

    A computational approach based on the thermal elastic plastic finite element method was developed for predicting welding residual stress in low carbon alloyed steel welds by taking into account the effect of the solid-state phase transformations.The kinetics of phase transformations was described by Johnson Mehl Avrami Kolmogrov (JMAK) equation for bainitic transition and by Koistinen-Marburger (K-M) relationship for martensitic transition.Moreover,an additive rule depending on volumetric phase fraction was adopted to represent the material property changes during heating and cooling.Consequently,the residual welding stresses in a 2.25Cr1Mo steel TIG welded plate were computed.Early calculation results suggest that the bainitic and martensitic transformations took place in the weld the heat-affected zone drastically reduce the residual longitudinal tensile stress in the region.

  19. Reduction of Residual Stress and Distortion in HY100 and HY130 High Strength Steels During Welding

    Science.gov (United States)

    1989-06-01

    High Yields) Steels for pressure hulls and special applications like flight decks where aluminum is impractical to use. HY80 is the most famous and...most widely used of the HYQ & T steels developed. Interest waned in widely using the steels with strengths above HY80 because of cracking problems...Reduction of Residual Stress and Distortion in HYI00 and HYI30 High Strength Steels During Welding CY) by _RICHARD ALLEN BASS B.S. Electrical

  20. Effects of welding technology on welding stress based on the finite element method

    Science.gov (United States)

    Fu, Jianke; Jin, Jun

    2017-01-01

    Finite element method is used to simulate the welding process under four different conditions of welding flat butt joints. Welding seams are simulated with birth and death elements. The size and distribution of welding residual stress is obtained in the four kinds of welding conditions by Q345 manganese steel plate butt joint of the work piece. The results shown that when using two-layers welding,the longitudinal and transverse residual stress were reduced;When welding from Middle to both sides,the residual stress distribution will change,and the residual stress in the middle of the work piece was reduced.

  1. 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

  2. Numerical Evaluation of Temperature Field and Residual Stresses in an API 5L X80 Steel Welded Joint Using the Finite Element Method

    Directory of Open Access Journals (Sweden)

    Jailson A. Da Nóbrega

    2016-01-01

    Full Text Available Metallic materials undergo many metallurgical changes when subjected to welding thermal cycles, and these changes have a considerable influence on the thermo-mechanical properties of welded structures. One method for evaluating the welding thermal cycle variables, while still in the project phase, would be simulation using computational methods. This paper presents an evaluation of the temperature field and residual stresses in a multipass weld of API 5L X80 steel, which is extensively used in oil and gas industry, using the Finite Element Method (FEM. In the simulation, the following complex phenomena were considered: the variation in physical and mechanical properties of the material as a function of the temperature, welding speed and convection and radiation mechanisms. Additionally, in order to characterize a multipass weld using the Gas Tungsten Arc Welding process for the root pass and the Shielded Metal Arc Welding process for the filling passes, the analytical heat source proposed by Goldak and Chakravarti was used. In addition, we were able to analyze the influence of the mesh refinement in the simulation results. The findings indicated a significant variation of about 50% in the peak temperature values. Furthermore, changes were observed in terms of the level and profile of the welded joint residual stresses when more than one welding pass was considered.

  3. Transformation behaviour and residual stresses in welding of new LTT filler materials; Umwandlungsverhalten und Eigenspannungen beim Schweissen neuartiger LTT-Zusatzwerkstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Kromm, Arne

    2011-07-06

    It has long been recognized that phase transformation plays a prominent part in the evolution of welding residual stresses in high-strength steel. But thus far, no approaches have been available to practically utilize this effect for welding residual stress control. Innovative Low Transformation Temperature (LTT) alloys featuring a characteristic chemical composition open up the possibility for joining high strength steels on their own strength level. Furthermore, martensitic phase transformation is supposed to permit deliberate adjustment of the welding residual stresses. Even though numerous investigations can be found in the literature on this issue, they provide only little insight into the interaction between phase transformation and resulting welding residual stresses. In order to clarify the problem presented, a matrix of LTT alloys was defined based on evaluated literature. The alloys were characterized with respect to their microstructure, mechanical properties and transformation temperature. Furthermore, it was possible within the scope of this study to realize in-situ experiments during welding using energy-dispersive diffraction methods. The new design and implementation of a welding setup specifically for use at synchrotron beamlines enabled the in-situ diffraction analysis of transformation processes. In the course of these experiments it could be managed to determine the transformation temperatures prevailing in the LTT weld metal. In addition the transformation kinetics of these alloys could be analyzed. The effects of the transformation behavior were analyzed based on the residual stress distributions at the surface of varying specimen geometries. The results illustrate on the one hand that the desired residual stress control by using LTT alloys is actually feasible. This is particularly found in cases with largely free shrinkage of the weld. With increasing shrinkage restraint, however, a shift of the residual stress level into the area of tension

  4. Study of residual stresses in welded joints of dual phase HSLA steel used in automotive industry; Estudo das tensoes residuais em juntas soldadas de aco ARBL bifasico usado na industria automobilistica

    Energy Technology Data Exchange (ETDEWEB)

    Barbato, D.S.; Fonseca, M.P. Cindra; Marques Junior, A.S.; Chuvas, T.C.; Pardal, J.M., E-mail: mcindra@vm.uff.b [Universidade Federal Fluminense (PGMEC/UFF), Niteroi, RJ (Brazil). Programa de Pos-graduacao em Engenharia Mecanica; Berretta, J.R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2010-07-01

    One way of weight reduction in automotive vehicles is through the use of high strength and low alloy (HSLA) steels, which enables the use of small thickness plates. Whereas the appearance of residual stresses is intrinsic to the welding process, this study evaluates the residual stresses generated in welded joints obtained by TIG and LASER welding processes and comparing them. Residual stresses were measured by X-rays diffraction technique, using a portable device with Cr{kappa}{alpha} radiation applying the double exposure method. It also evaluates the influence of shot peening treatment applied after welding, in the bend tests conducted for both welding conditions and TIG welded joints showed higher stability of compressive stresses after welding. The metallographic analysis by optical microscopy complemented the welded joints characterization. (author)

  5. Residual stress reduction in beam welded joints by means of stress redistribution using defocused electron or laser beams; Eigenspannungsreduktion in strahlgeschweissten Naehten mittels Spannungsumlagerung durch den Einsatz defokussierter Elektronen- bzw. Laserstrahlen

    Energy Technology Data Exchange (ETDEWEB)

    Toelle, Florian

    2013-08-01

    Among the multiple advantages of beam welding processes the high longitudinal residual stresses in beam welds ranging till the local yield stress are one disadvantage. These high stresses can influence the service life of the welded components. The residual stresses in other welding processes exist in an equal high level but primarily in the transverse direction to the weld. To mitigate the high residual stresses a couple of methods were developed for these welding processes in the last decades. However these methods need large contact surfaces next to the welds for the installation of matched heating and cooling elements and other additional equipment. Furthermore, the previous developed stress mitigating processes offer a low efficiency for the small beam welds. The stress reduction by using the welding source after the welding process for a remote heat treatment of the welded components afford a flexible tool for the stress mitigation in beam welds. This method does not need any additional equipment and it is applicable for complex welding and component geometries. During this post welding heat treatment the material next to the weld is heated by the defocused electron or by the defocused laser beam, respectively, to temperatures of some hundreds degree Celsius. Hereby low plastic deformations in these regions are generated. While cooling down due to the thermal shrinkage the material between the weld and the heat treated region is compressed in longitudinal direction to the weld. This intermediate material zone constrained the shrinkage of the weld while cooling down from the melting temperature and leads to the high longitudinal residual stresses in the weld. In consequence of the compression of this intermediate zones by the heat treated zones the resistance to the shrinkage of the weld is lowered and the longitudinal stresses in the weld are reduced. In the process the quantity of the stress reduction is controlled by the selection of the process parameters

  6. Influence of treatment by vibration in residual stress generated in the laser welding of HSLA and IF steels; Influencia do tratamento de vibracao nas tensoes residuais geradas na soldagem a laser de acos ARBL e IF

    Energy Technology Data Exchange (ETDEWEB)

    Chuvas, T.C.; Fonseca, M.P. Cindra, E-mail: chuvas@vm.uff.b [Universidade Federal Fluminense (PGMEC/UFF), Niteroi, RJ (Brazil). Programa de Pos-graduacao em Engenharia Mecanica; Castello, D.A. [Universidade Federal do Rio de Janeiro (DEM/UFRJ), RJ (Brazil). Dept. de Engenharia Mecanica

    2010-07-01

    The stress relieving treatment by vibration is a new technology under development, which has many advantages over thermal methods. In this work was analyzed the surface residual stress generated in the laser welding of biphasic HSLA and IF steels, both used in the automotive industry. Residual stresses were measured by X-ray diffraction, by the sen{sup 2} {Psi} method. Residual stresses generated in the welding of the samples were tensile at all points measured. After welding, the samples were submitted to the mechanical vibration treatment. Some samples presented a significant reduction in the stress values. The welded joints were also characterized by optical microscopy. (author)

  7. An Integrated Modeling Approach for Predicting Process Maps of Residual Stress and Distortion in a Laser Weld: A Combined CFD-FE Methodology

    Science.gov (United States)

    Turner, Richard P.; Panwisawas, Chinnapat; Sovani, Yogesh; Perumal, Bama; Ward, R. Mark; Brooks, Jeffery W.; Basoalto, Hector C.

    2016-10-01

    Laser welding has become an important joining methodology within a number of industries for the structural joining of metallic parts. It offers a high power density welding capability which is desirable for deep weld sections, but is equally suited to performing thinner welded joints with sensible amendments to key process variables. However, as with any welding process, the introduction of severe thermal gradients at the weld line will inevitably lead to process-induced residual stress formation and distortions. Finite element (FE) predictions for weld simulation have been made within academia and industrial research for a number of years, although given the fluid nature of the molten weld pool, FE methodologies have limited capabilities. An improvement upon this established method would be to incorporate a computational fluid dynamics (CFD) model formulation prior to the FE model, to predict the weld pool shape and fluid flow, such that details can be fed into FE from CFD as a starting condition. The key outputs of residual stress and distortions predicted by the FE model can then be monitored against the process variables input to the model. Further, a link between the thermal results and the microstructural properties is of interest. Therefore, an empirical relationship between lamellar spacing and the cooling rate was developed and used to make predictions about the lamellar spacing for welds of different process parameters. Processing parameter combinations that lead to regions of high residual stress formation and high distortion have been determined, and the impact of processing parameters upon the predicted lamellar spacing has been presented.

  8. Influence of residual stress on the HIC resistance of high frequency induction welded pipes with regard to process-specific influencing factors

    Energy Technology Data Exchange (ETDEWEB)

    Krageloh, Joachim; Brauer, Holger; Bosch, Christoph [Salzgitter Mannesmann Line Pipe GmbH, (Germany)

    2010-07-01

    The industry needs to meet growing demand for pipes with high resistance to sour service conditions. Salzgitter Mannesmann Line Pipe is developing new product ranges of high frequency induction (HFI) welded pipes. This study investigated the influence of residual stress on the resistance of HFI welded pipes to HIC with focus on process-specific influencing factors. Four materials with different strengths were tested. Three of them were not manufactured for sour service and so were sure to show significant HIC damage during the tests. The specimens were studied using the cross-sectioning method for longitudinal and circumferential residual stress. A four-point-bend test in line with ADTM G 39 was also done to determine the HIC resistance of the pipe specimens. The results provide a characteristic HIC value and crack area ratio, CAR. This study showed that residual stress induced by HFI welding of pipes has no negative impact on resistance to HIC.

  9. Experimental determination of residual stress

    Science.gov (United States)

    Ferguson, Milton W.

    1991-01-01

    Residual stresses in finished parts have often been regarded as factors contributing to premature part failure and geometric distortions. Currently, residual stresses in welded structures and railroad components are being investigated. High residual stresses formed in welded structures due primarily to the differential contractions of the weld material as it cools and solidifies can have a profound effect on the surface performance of the structure. In railroad wheels, repeated use of the brakes causes high residual stresses in the rims which may lead to wheel failure and possible derailment. The goals of the study were: (1) to develop strategies for using x-ray diffraction to measure residual stress; (2) to subject samples of Inconel 718 to various mechanical and heat treatments and to measure the resulting stress using x-ray diffraction; and (3) to measure residual stresses in ferromagnetic alloys using magnetoacoustics.

  10. Residual stress evaluation of coating films using welding residual stress and deformation analysis system. Yosetsu zanryu oryoku/henkei kaiseki system ni yoru coating himaku no zanryu oryoku hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Y.; Tanaka, K.; Takahashi, M.; Okada, T.; Saito, M. (Toshiba Corp., Tokyo (Japan)); Toyoda, M. (Osaka Univ., Osaka (Japan). Faculty of Engineering)

    1992-09-25

    With the objective that anybody having the basic knowledge on a simple welding technique can do easily welding residual stress and deformation analysis in an interactive mode, the welding residual stress and deformation analysis system (WRED) using a lap-top personal computer is being developed. In this report, an analytical study as well as an experimental study have been made on applicability of this system from the viewpoint of evaluating the residual stress chararcteristics of coating members in the WRED. In particular, the residual stress characteristics of ceramic coating films and those of graded coating members are described in detail. Part of the obtained results is as follows; as a result of the analysis by the WRED system of ceramic coating members processed each by the CVD method, the PVD method and the plasma flame coating method, only the CVD method and the plasma flame coating method have agreed well with the result of the residual stress measurement by the X-ray method. 12 refs., 8 figs., 2 tabs.

  11. Combined effects of weld-induced residual stresses and flaws on the fracture strength of Ti-5Al-2.5Sn

    Science.gov (United States)

    Hall, L. R.

    1973-01-01

    The combined effects of weld-induced residual stresses and flaws on fracture strength were experimentally evaluated by testing Ti-5Al-2.5Sn surface flawed specimens at -320F (-195C) in liquid nitrogen. Flaws were located in weld metal with crack planes either parallel to or perpendicular to gas tungsten arc weld centerlines, and in base metal with the crack plane perpendicular to the rolling direction. Tests were conducted using two different flaw sizes to effect fracture stresses at two different levels including one level either at or near, and one level well below the tensile yield strength. Three different residual stress levels were generated, measured, and tested. Results were evaluated using modified linear elastic fracture mechanics theory.

  12. Combined effects of weld-induced residual stresses and flaws on the fracture strength of Ti-5Al-2.5Sn

    Science.gov (United States)

    Hall, L. R.

    1973-01-01

    The combined effects of weld-induced residual stresses and flaws on fracture strength were experimentally evaluated by testing Ti-5Al-2.5Sn surface flawed specimens at -320F (-195C) in liquid nitrogen. Flaws were located in weld metal with crack planes either parallel to or perpendicular to gas tungsten arc weld centerlines, and in base metal with the crack plane perpendicular to the rolling direction. Tests were conducted using two different flaw sizes to effect fracture stresses at two different levels including one level either at or near, and one level well below the tensile yield strength. Three different residual stress levels were generated, measured, and tested. Results were evaluated using modified linear elastic fracture mechanics theory.

  13. 弯曲箱型结构焊接顺序对残余应力的影响%Influence of Welding Sequence of Bend Box Structure on Welding Residual Stress

    Institute of Scientific and Technical Information of China (English)

    韩双宗; 王发展

    2016-01-01

    Finite element model of bend box structure was established.Different welding schemes were analyzed by local to whole hierarchical optimization method.The influence laws of welding sequence on the residual stress were studied,and then the optimum welding scheme was proposed.The results show that the welding sequence which can reduce transient heat input concentration could reduce the maximum residual tensile stress prominently for single weld bead,and the reduction rate is 17.7%.The change of welding sequence and direction could control the residual stress for dissimilar weld beads to some degree.But,the change of whole welding sequence could not change the value and distribution of residual stress prominently.%建立了弯曲箱形结构的有限元模型,采用从局部到整体的逐层优化法,对不同焊接方案进行分析,研究了焊接顺序对残余应力的影响规律,进而提出最优焊接方案.结果表明:对于单条焊道,减少瞬时热输入集中的焊接顺序能大幅降低残余拉应力的最大值,降低率达到17.7%;改变焊道间的焊接顺序及焊接方向也能在一定程度上控制残余应力,但是整体焊接顺序的变化并没有显著改变残余应力的大小和分布状况.

  14. Applying electron backscattering diffraction to macroscopic residual stress characterisation in a dissimilar weld

    OpenAIRE

    Abburi Venkata, K.; Truman, C.E.; Coules, H.E.; Warren, A D

    2017-01-01

    Dissimilar metal welds are complicated in nature because of the complex microstructure characteristics in the weld fusion zone. It is often necessary to know the phase distribution in a dissimilar metal weld especially at the interface such as fusion zone and heat affected zone to be able to predict the behaviour of the joint and its fitness for service. In this paper, a dissimilar metal weld made between ferritic/martensitic modified 9Cr-1Mo steel (P91) and austenitic AISI 316LN stainless st...

  15. Residual Stresses in Thick Bi-metallic Fusion Welds: a Neutron Diffraction Study

    NARCIS (Netherlands)

    Ohms, C.

    2013-01-01

    Welding is applied in many industrial sectors to join components, and has become an important manufacturing process because it enables the fabrication of structures that could not otherwise be constructed. Weld regions have inhomogeneous microstructures and are more susceptible to crack initiation a

  16. Residual Stresses in Thick Bi-metallic Fusion Welds: a Neutron Diffraction Study

    NARCIS (Netherlands)

    Ohms, C.

    2013-01-01

    Welding is applied in many industrial sectors to join components, and has become an important manufacturing process because it enables the fabrication of structures that could not otherwise be constructed. Weld regions have inhomogeneous microstructures and are more susceptible to crack initiation a

  17. Residual Stresses in Thick Bi-metallic Fusion Welds: a Neutron Diffraction Study

    NARCIS (Netherlands)

    Ohms, C.

    2013-01-01

    Welding is applied in many industrial sectors to join components, and has become an important manufacturing process because it enables the fabrication of structures that could not otherwise be constructed. Weld regions have inhomogeneous microstructures and are more susceptible to crack initiation

  18. Residual Stress Measurement and Calibration for A7N01 Aluminum Alloy Welded Joints by Using Longitudinal Critically Refracted ( LCR) Wave Transmission Method

    Science.gov (United States)

    Zhu, Qimeng; Chen, Jia; Gou, Guoqing; Chen, Hui; Li, Peng; Gao, W.

    2016-10-01

    Residual stress measurement and control are highly important for the safety of structures of high-speed trains, which is critical for the structure design. The longitudinal critically refracted wave technology is the most widely used method in measuring residual stress with ultrasonic method, but its accuracy is strongly related to the test parameters, namely the flight time at the free-stress condition ( t 0), stress coefficient ( K), and initial stress (σ0) of the measured materials. The difference of microstructure in the weld zone, heat affected zone, and base metal (BM) results in the divergence of experimental parameters. However, the majority of researchers use the BM parameters to determine the residual stress in other zones and ignore the initial stress (σ0) in calibration samples. Therefore, the measured residual stress in different zones is often high in errors and may result in the miscalculation of the safe design of important structures. A serious problem in the ultrasonic estimation of residual stresses requires separation between the microstructure and the acoustoelastic effects. In this paper, the effects of initial stress and microstructure on stress coefficient K and flight time t 0 at free-stress conditions have been studied. The residual stress with or without different corrections was investigated. The results indicated that the residual stresses obtained with correction are more accurate for structure design.

  19. Simulation of Weld Mechanical Behavior to Include Welding-Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes

    Science.gov (United States)

    2015-11-01

    JOHN J KINGMAN ROAD SUITE 0944 FORT BELVOIR, VA 22060-6218 COMMANDER ATTN: SEA 05P2 NAVAL SEA SYSTEMS COMMAND 5 1333 ISAAC HULL AVENUE S.E...was performed by the Welding, Processing, and Nondestructive Evaluation Branch (Code 611) and the Hull Response and Protection Branch (Code 664) of...COMMAND 2 1333 ISAAC HULL AVENUE S.E. WASHINGTON NAVY YARD WASHINGTON, DC 20376 ATTN: Gardner, Sensharma COMMANDER ATTN: SEA 05V NAVAL SEA

  20. Experimental investigation and finite element simulation of laser beam welding induced residual stresses and distortions in thin sheets of AA 6056-T4

    Energy Technology Data Exchange (ETDEWEB)

    Zain-ul-abdein, Muhammad [Universite de Lyon, CNRS, INSA-Lyon, LaMCoS UMR5259, F69621 (France); Nelias, Daniel, E-mail: daniel.nelias@insa-lyon.fr [Universite de Lyon, CNRS, INSA-Lyon, LaMCoS UMR5259, F69621 (France); Jullien, Jean-Francois [Universite de Lyon, CNRS, INSA-Lyon, LaMCoS UMR5259, F69621 (France); Deloison, Dominique [EADS, 12 Rue Pasteur, BP 76, 92152 Suresnes Cedex (France)

    2010-05-15

    Laser beam welding has recently found its application in the fabrication of aircraft structures where fuselage panels, made of thin sheets of AA 6056-T4 (an aluminium alloy), are welded with stiffeners of the same material in a T-joint configuration. The present work simulates laser beam welding induced residual stresses and distortions using industrially employed thermal and mechanical boundary conditions. Various measurements performed on small-scale welded test specimens provide a database of experimental results that serves as a benchmark for qualification of the simulation results. The welding simulation is performed with the commercial finite element software Abaqus and a Fortran programme encoding a conical heat source with Gaussian volumetric distribution of flux. A sequentially coupled temperature-displacement analysis is undertaken to simulate the weld pool geometry, transient temperature and displacement fields. The material is assumed to follow an elasto-plastic law with isotropic hardening behaviour (von Mises plasticity model). A comparison between the experimental and simulation results shows a good agreement. Finally, the residual stress and strain states in a T-joint are predicted.

  1. 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).

  2. Avaliação do efeito da energia de soldagem sobre as tensões residuais resultantes em juntas soldadas com multipasse Welding energy input evaluation on the final residual stresses in multipass welded joints

    Directory of Open Access Journals (Sweden)

    George Luiz Gomes de Oliveira

    2010-09-01

    Full Text Available A energia de soldagem pode ser ajustada tanto por meio do controle da potência (tensão e corrente de soldagem quanto por meio da velocidade de soldagem. Tais formas de ajustes modificam os efeitos da energia de soldagem sobre a junta, o que pode influenciar de forma distinta as tensões residuais resultantes na mesma. Desta forma, o objetivo deste trabalho é avaliar o efeito da energia de soldagem, considerando seu ajuste através da alteração individual e independente da corrente e da velocidade de soldagem, sobre as tensões residuais resultantes em juntas soldadas com multipasse. Foram empregadas amostras de aço estrutural chanfradas em meio-v e soldadas utilizando eletrodo revestido. Aplicaram-se três energias de soldagem obtidas por meio de três níveis distintos de corrente e de velocidade de soldagem. As amostras foram levadas a um difratômetro de raios-x portátil onde foram levantados os perfis de tensões residuais na superfície das mesmas. Uma verificação importante foi que diferentes parâmetros de soldagem que resultam em aportes térmicos "iguais", geram níveis diferentes de tensões residuais, ou seja, a energia de soldagem não pode ser considerada de forma isolada em análises de níveis de tensões residuais resultantes da soldagem multipasse.The energy input in welding can be adjusted by either control of welding power (voltage and welding current or welding speed. These different ways of changing can result in different residual stress profiles in the welded joint. Then, the aim of this work is to evaluate, in an independent way, the welding energy input, current and speed effect on the final residual stresses of a multipass joint. Semi-v chamfered samples of structural steel and SMAW process was used. Three different levels of welding current and speed was employed in order to get three levels of energy input. The residual stress measurement was accomplished through X-ray diffraction, using a minidiffractometer

  3. Effect of width of repair welding on stress distribution of dissimilar metal butt weld of nuclear piping

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Won Shik; Lee, Hwee Seung; Huh, Nam Su [Seoul National Univ. of Science and Technology, Seoul (Korea, Republic of)

    2013-10-15

    In the present work, the welding residual stress due to repair welding and the stress redistribution behavior due to primary pressure are investigated via 2-dimensional non-linear finite element analyses. In particular, the effect of repair welding width on stress distribution is emphasized. Although, large tensile residual stresses are produced at the PWSCC sensitive region due to repair welding, these stresses are highly reduced due to stress redistribution caused by primary load. Based on the present finite element results, it has been revealed that the effect of width of repair welding on stress distribution is not significant. In the past few years, many numerical and experimental works have been made to assess a structural integrity of cracked components subjected to primary water stress corrosion cracking in dissimilar metal weld (DMW) using Alloys 82/182 in nuclear industries worldwide. These works include a prediction of weld residual stresses in dissimilar metal weld by either numerical or experimental works since an accurate estimation of residual stress distribution in dissimilar metal weld is the most important element for integrity assessment of components subjected to primary water stress corrosion cracking. During an actual welding process, in general, a repair welding is often performed when a defect indication is detected during post-welding inspection. It has been revealed that such a repair welding could lead to higher tensile residual stress in dissimilar metal weld, which is detrimental to the crack growth due to primary water stress corrosion cracking. Thus, the prediction of residual stress considering a repair welding is needed, and then many efforts were made on this issue. In the present work, the effect of width of repair welding on stress distribution of dissimilar metal butt weld of nuclear piping is evaluated based on the detailed 2-dimensional non-linear finite element analyses. For this purpose, the welding residual stress due to

  4. Residual stresses, defects and fatigue cycling in friction stir butt welds in 5383-H321 and 5083-H321 aluminium alloys

    Energy Technology Data Exchange (ETDEWEB)

    James, M.N.; Bradley, G.R. [Mechanical and Marine Engineering, Univ. of Plymouth, Plymouth (United Kingdom); Hattingh, D.G. [Mechanical Engineering, PE Technikon, Port Elizabeth (South Africa); Hughes, D.J.; Webster, P.J. [FaME38, ILL-ESRF, Grenoble (France)

    2003-07-01

    This paper presents results from a substantial investigation of residual stresses and defects associated with single pass and double pass friction stir welds in 5083-H321 and 5383-H321 aluminium alloys. The residual stress part of the paper summarises data on their as-welded magnitude and plate-to-plate variation, together with their modification during applied bending fatigue loading corresponding to cyclic lives of 10{sup 5} and 10{sup 7} cycles. Results indicate fairly low initial peak tensile stresses both parallel with, and perpendicular to, the weld run. Peak tensile stresses occur just outside the tool shoulder with values typically in the range 0-30 MPa. Peak compressive stresses have much higher magnitudes (typically in the range -50 MPa to -140 MPa) and occur at distances of up to 40 mm from the weld centreline. Significant plate-to-plate variability in residual stress magnitudes exists, and fatigue cycling can raise peak tensile stresses by as much as a factor of four (to around 80 MPa). This has significant potential influence on fatigue life prediction. The paper also presents data on the occurrence of partial-fusion defects (PFD's or so-called 'kissing bonds' or 'onion-skin' defects) as a function of tool travel speed (in the range 80-200 mm/min), and their influence on fatigue life. Results indicate that PFD's can sometimes be associated with crack initiation, but that their major effect is more likely to appear when levels of plastic deformation are high, i.e. during relatively fast fatigue crack growth or during fast fracture. (orig.)

  5. Transformation behaviour and residual stresses in welding of new LTT filler materials; Umwandlungsverhalten und Eigenspannungen beim Schweissen neuartiger LTT-Zusatzwerkstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Kromm, Arne

    2011-07-06

    It has long been recognized that phase transformation plays a prominent part in the evolution of welding residual stresses in high-strength steel. But thus far, no approaches have been available to practically utilize this effect for welding residual stress control. Innovative Low Transformation Temperature (LTT) alloys featuring a characteristic chemical composition open up the possibility for joining high strength steels on their own strength level. Furthermore, martensitic phase transformation is supposed to permit deliberate adjustment of the welding residual stresses. Even though numerous investigations can be found in the literature on this issue, they provide only little insight into the interaction between phase transformation and resulting welding residual stresses. In order to clarify the problem presented, a matrix of LTT alloys was defined based on evaluated literature. The alloys were characterized with respect to their microstructure, mechanical properties and transformation temperature. Furthermore, it was possible within the scope of this study to realize in-situ experiments during welding using energy-dispersive diffraction methods. The new design and implementation of a welding setup specifically for use at synchrotron beamlines enabled the in-situ diffraction analysis of transformation processes. In the course of these experiments it could be managed to determine the transformation temperatures prevailing in the LTT weld metal. In addition the transformation kinetics of these alloys could be analyzed. The effects of the transformation behavior were analyzed based on the residual stress distributions at the surface of varying specimen geometries. The results illustrate on the one hand that the desired residual stress control by using LTT alloys is actually feasible. This is particularly found in cases with largely free shrinkage of the weld. With increasing shrinkage restraint, however, a shift of the residual stress level into the area of tension

  6. Study on 3D finite element simulation of high frequency welded pipe welding residual stress%高频直缝焊管焊接残余应力的三维有限元模拟研究

    Institute of Scientific and Technical Information of China (English)

    于恩林; 韩毅; 谷绪地; 张洪亮

    2012-01-01

    基于高频直缝焊管焊接热源的计算结果,综合考虑材料的物理属性随温度的高度非线性变化,以及高频加热的焊缝热影响区特有的温度分布规律,利用ANSYS有限元软件建立了高频直缝焊管焊接残余应力的三维有限元模型.获得了高频焊管温度场和残余应力场的分布规律,并对结果进行了分析.通过后处理模块,给出了焊缝部位残余应力的分布趋势,并分析了高频感应焊接残余应力的主要形成原因.发现焊缝附近的轴向残余应力较大,其中有些数值接近材料的屈服强度,而周向残余应力仅为材料屈服应力的1/3左右,径向残余应力数值较小,工程上可以忽略.%Based on the high-frequency longitudinal welding heat calculations, ANSYS finite element software is used to establish the three-dimensional finite element model of welding residual stress. Physical properties of materials with highly non-linear changes in temperature and high-frequency heating of the weld heat affected zone-specific temperature distribution are considered. High-frequency welded pipe temperature field and residual stress field distribution are obtained, and the results are analyzed. Trends of the main causes of the high frequency induction welding residual stress are analyzed through the post-processing module. The axial residual stress of near the weld seam are larger, and some of the values are close to the material yield strength. Residual stress in the circumferential direction is one-third of the material yield stress, and radial residual stress value is smaller that in projects can be ignored.

  7. 3D finite element simulation of temperature distribution, residual stress and distortion on 304 stainless steel plates using GTA welding

    Energy Technology Data Exchange (ETDEWEB)

    Venkatkumar, D.; Ravindran, D. [National Engineering College, Tamilnadu (India)

    2016-01-15

    In the present study, the distortion induced in rectangular plate of AISI 304 SS during autogenous GTA welding process is measured experimentally and further validated using Finite element (FE) analysis. The thermal histories are measured at fixed locations over the surface of the plate and the results are compared with FE analysis. The Gaussian surface and Volumetric heat source models are simulated and transient heat transfer analysis is performed. The heat source models have been tested with two different speeds. The effectiveness of change in thermal histories of the heat sources have been studied and reported. In FE analysis, the sequentially coupled thermomechanical analysis is performed using the thermal histories as input and the distortion of the plates are predicted and compared with experimental measurements. The large and small displacement theories are employed for the above purpose and the effectiveness of the theories are reported. The edge deformation of the plates have been measured and validated for both the theories. The residual stress and distortion at the mid span are predicted and discussed. The results predicted using large displacement theory is in good agreement with measured values.

  8. Induction-assisted laser beam welding of a thermomechanically rolled HSLA S500MC steel: A microstructure and residual stress assessment

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, R.S. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin (Germany); Former at Max-Planck Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Corpas, M. [Former at Max-Planck Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Moreto, J.A. [Universidade de São Paulo, Escola de Engenharia de São Carlos, CEP 13566-590 São Carlos, SP (Brazil); Jahn, A.; Standfuß, J. [Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden (Germany); Kaysser-Pyzalla, A. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin (Germany); Former at Max-Planck Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Pinto, H., E-mail: haroldo@sc.usp.br [Former at Max-Planck Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Universidade de São Paulo, Escola de Engenharia de São Carlos, CEP 13566-590 São Carlos, SP (Brazil)

    2013-08-20

    The present work deals with the effect of different combinations of induction heating and autogenous CO{sub 2} laser welding on the gradients of microstructure, microhardness and residual stresses in butt-joints of thermomechanically processed S500MC steel grade. Five strategies were pursued by varying the inductor position with respect to the laser beam. This enabled in-line pre-, post-, and simultaneous pre- and post-heating as well as annealing of the fusion and heat-affected zones. The induction-assisted CO{sub 2} laser welding strategies were compared to individual CO{sub 2} and Nd:YAG fiber welding procedures. The results demonstrate that induction heating can be combined to laser welding in order to effectively increase the cooling times. Martensite formation could be suppressed within the fusion and heat-affected zones and smooth hardness distributions were obtained by pre-heating and combined pre- and post-heating. The tensile residual stresses are, however, still of significance because of the high transformation temperatures (>500 °C) observed for the S500MC steel. This allowed for extensive thermal contraction after exhaustion of the austenite to ferrite transformation.

  9. Thermal Stresses in Welding

    DEFF Research Database (Denmark)

    Hansen, Jan Langkjær

    1998-01-01

    Studies of the transient temperature fields and the hereby induced deformations and stressses in a butt-welded mild steel plate modelledrespectively in 2D plane stress state (as well as plane strain state) and in full 3D have been done. The model has been implemented in the generalpurpose FE...

  10. 焊管残余应力研究进展及展望%Research Progress and Prospect of Residual Stress in Welded Pipe

    Institute of Scientific and Technical Information of China (English)

    李霄; 熊庆人; 石凯; 刘彦明; 李健; 胥聪敏; 张燕娜

    2009-01-01

    During the manufacturing procedure,the pipe body was formed,welded,pressurized,bended and coated successively,and residual stress was induced into the pipe body which is closely related with the service life,and many researches are about it.In this paper the main residual stress studing methodes and main research results are reviewed.It has a very strong relationship between residual stess and forming process.The residual stress of general LSAW(Longitudinal Submerged Arc Welded) pipe is lower and more uniform than HSAW(Helical Submerged Arc Welded) pipe.Hydrotest and expanding process can effectively reduce residual stress,but the relationship among hydrotest pressure,expanding parameter and residual stress need to be defined through a lot of research.Meanwhile the application of ring-slit method and magnetic method,the model of HSAW pipe forming,the distribution along thickness of residual stress need to be studied deeply.%在焊管制造过程中需进行弯曲成型、焊接、水压、弯管、防腐等工艺过程,这些工艺过程造成的残余应力关系到焊管的服役寿命.介绍了焊管残余应力的研究方法、研究成果.指出,焊管的残余应力与其成型工艺关系重大,一般直缝焊管的残余应力水平低、分布均匀,螺旋焊管的残余应力水平高,且分布均匀性差.水压试验和扩径可以有效降低残余应力,但水压和扩径参数与残余应力的具体关系仍需要进行大量研究才能确定.最后指出,对切环法与磁测法的应用、螺旋焊管成型的精确模型、残余应力沿厚度方向的分布等问题仍需要进行深入研究.

  11. Comparative study of residual stress by table of coordinates and X-ray diffraction in a welded joint; Estudo comparativo das tensoes residuais por mesa de coordenadas e DR-X numa junta soldada

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira Filho, A.V.; Rolim, T.L.; Yadava, Y.P.; Ferreira, R.A.S., E-mail: anibal_siqueira@yahoo.com.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Engenharia Mecanica; Cardoso, F.I.B. [Universidade de Pernambuco (POLI/UPE), Recife, PE (Brazil); Guimaraes, P.B. [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco, Recife, PE (Brazil)

    2010-07-01

    Residual stresses in a welded joint of naval steel ASTM AH-32 was measured either by the displacements of referenced points with a coordinated table (CT) or by x-ray diffraction (X-DR) after welding. For all tests, the welding was performed by a certified welder in the SMAW process, using an AWS E 7018 G3 electrode. Before welding, small holes evenly spaced were made in the specimens to be mapped on a coordinated table (CT). After labeling, the specimens were submitted to the welding process and new measurements by (CT) to evaluate the displacements produced by the tensions generated. In parallel, residual stress were measured by DR-X for validation of this new measurement methodology. (author)

  12. Non-destructive Residual Stress Analysis Around The Weld-Joint of Fuel Cladding Materials of ZrNbMoGe Alloys

    Directory of Open Access Journals (Sweden)

    Parikin

    2003-08-01

    Full Text Available The residual stress measurements around weld-joint of ZrNbMoGe alloy have been carried out by using X-ray diffraction technique in PTBIN-BATAN. The research was performed to investigate the structure of a cladding material with high temperature corrosion resistance and good weldability. The equivalent composition of the specimens (in %wt. was 97.5%Zr1%Nb1%Mo½%Ge. Welding was carried out by using TIG (tungsten inert gas technique that completed butt-joint with a current 20 amperes. Three region tests were taken in specimen while diffraction scanning, While diffraction scanning, tests were performed on three regions, i.e., the weldcore, the heat-affected zone (HAZ and the base metal. The reference region was determined at the base metal to be compared with other regions of the specimen, in obtaining refinement structure parameters. Base metal, HAZ and weldcore were diffracted by X-ray, and lattice strain changes were calculated by using Rietveld analysis program. The results show that while the quantity of minor phases tend to increase in the direction from the base metal to the HAZ and to the weldcore, the quantity of the ZrGe phase in the HAZ is less than the quantity of the ZrMo2 phase due to tGe element evaporation. The residual stress behavior in the material shows that minor phases, i.e., Zr3Ge and ZrMo2, are more dominant than the Zr matrix. The Zr3Ge and ZrMo2 experienced sharp straining, while the Zr phase was weak-lined from HAZ to weldcore. The hydrostatic residual stress ( in around weld-joint of ZrNbMoGe alloy is compressive stress which has minimum value at about -2.73 GPa in weldcore region

  13. Experimental investigation of the residual stresses of 304L tubular welded joints; Caracterisation des contraintes residuelles sur assemblages soudes tubulaires en acier 304L

    Energy Technology Data Exchange (ETDEWEB)

    Monin, L.; Panier, S.; Hariri, S.; Zakrzewski, D. [Ecole des Mines de Douai, 941, rue Charles Bourseul, BP 10838, 59508 DOUAI Cedex (France); Faidi, C. [EDF-SEPTEN, 12-14, avenue Dutrievoz, 69628 VILLEURBANNE (France)

    2007-07-01

    In the nuclear energy industry, the use of components made of austenitic stainless steel is widely spread, because of its specific thermal properties. The assembly of these pressure vessels and piping by welding processes often requires surface mechanical operations. These operations aim at hardening surfaces and lowering roughness. Nevertheless the main effect of these operations is the occurrence of residual stresses which can have positive or negative effects on the fatigue life. In this study, we focus on the evaluation and relaxation of residual stresses level on AISI 304L austenitic stainless steel tubular welded structures. Some of these rings are base metal rings (which stand as reference), the rest presents a longitudinal and symmetrical Y-weld joint, with or without grinding. Surface residual stresses, and their relaxation, were determined by using the X-ray diffraction method. (authors) [French] L'utilisation de composants en acier inoxydable austenitique, aux proprietes thermiques bien specifiques, est tres courante dans le domaine de la production d'energie nucleaire. Les procedes d'assemblage par soudage de ces equipements sous pression requierent des traitements de parachevement mecanique afin d'ameliorer l'etat de surface et modifier l'etat mecanique en introduisant des contraintes residuelles, qui peuvent avoir une influence sur la duree de vie de la structure. Cette etude porte sur la caracterisation et la relaxation des contraintes residuelles, determinees sur des eprouvettes annulaires specifiques en acier inoxydable austenitique de type 304L, a l'etat brut ou avec des soudures, arasees ou non. La methode de determination utilisee est la diffraction des rayons X. La relaxation de ces contraintes au cours d'essais de fatigue est egalement etudiee. (auteurs)

  14. Present Study and Prospect of Friction Stir Welding Residual Stress%搅拌摩擦焊残余应力研究现状及展望

    Institute of Scientific and Technical Information of China (English)

    牛鹏亮; 李文亚

    2015-01-01

    搅拌摩擦焊是一种新型的固相焊接技术,目前国内外的研究主要集中在工艺、组织、力学性能等方面,而有关搅拌摩擦焊缝内部残余应力的研究相对较少。由于检测设备的限制,国内主要采用有损检测方法,无损检测方法却很少。详细综述了国内有关搅拌摩擦焊件内部残余应力测试的钻孔法、云纹干涉法,以及国内外无损检测方法中的X射线衍射法、中子衍射法和高能同步辐射法的研究概况,讨论了各种检测方法的优缺点,对未来搅拌摩擦焊残余应力的研究作了展望。%Friction stir welding is a new solid-state welding technology. At present, studies of domestic and overseas focus on processes, microstructure and mechanical properties. Studies on the initial residual stress of friction stir welding are relative fewer. Because of the limited testing equipment, the destructive tests are usually adopted by domestic research-ers, but the non-destructive tests are so fewer. The destructive, such as hole-drilling and moire interferometry, and non-destructive tests, such as X-ray diffraction, neutron diffraction and synchrotron radiation, are summarized in detail. Mean-while, the advantages and disadvantages of the detection methods are discussed and a prospection for the study of friction stir welding residual stress is made.

  15. Stress Distribution in the Dissimilar Metal Butt Weld of Nuclear Reactor Piping due to the Simulation Technique for the Repair Welding

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hweeseung; Huh, Namsu [Seoul Nat' l Univ. of Science and Technology, Seoul (Korea, Republic of); Kim, Jinsu; Lee, Jinho [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2013-05-15

    During welding, the dissimilar metal butt welds of nuclear piping are typically subjected to repair welding in order to eliminate defects that are found during post-weld inspection. It has been found that the repair weld can significantly increase the tensile residual stress in the weldment, and therefore, accurate estimation of the weld residual stress due to repair weld, especially for dissimilar metal welds using Ni-based alloy 82/182 in nuclear components, is of great importance in order to assess susceptibility to primary water stress corrosion cracking. In the present study, the stress distributions of dissimilar metal butt welds in nuclear reactor piping subjected to repair weld were investigated based on detailed nonlinear finite element analyses. Particular emphasis was placed on the variation of the stress distribution in the dissimilar metal butt weld according to the finite element welding analysis sequence for the repair welding process.

  16. Evaluation of residual stresses in electron-beam welded Zr2.5Nb0.9Hf Zircadyne flange mock-up of a reflector vessel beam tube flange

    Energy Technology Data Exchange (ETDEWEB)

    Muránsky, O., E-mail: ondrej.muransky@ansto.gov.au [Institute of Material Engineering, ANSTO, Locked Bag 2001, Kirrawee DC, 2234 NSW (Australia); Holden, T.M. [Northern Stress Technologies, Deep River, Ontario, Canada K0J 1P0 (Canada); Kirstein, O. [European Spallation Source, EES AB, Tunavagen 24, SE-211 00 Lund (Sweden); James, J.A. [Open University, Materials Engineering, Milton Keynes MK7 6BJ (United Kingdom); Paradowska, A.M. [Bragg Institute, ANSTO, Locked Bag 2001, Kirrawee DC, 2234 NSW (Australia); Edwards, L. [Institute of Material Engineering, ANSTO, Locked Bag 2001, Kirrawee DC, 2234 NSW (Australia)

    2013-07-15

    The dual-phase alloy Zr2.5Nb alloy is an important nuclear material, because of its use in current and possible use in future nuclear reactors. It is, however, well-known that Zr2.5Nb weldments can fail through a time-dependent mechanism called delayed hydride cracking which is typically driven by the presence of tensile residual stresses. With a view to understanding the development of residual stresses associated with Zr2.5Nb welds the current study focuses on the evaluation of the residual stresses in a mock-up of a reactor beam tube flange made from Zr2.5Nb0.9Hf. The present results suggests that, like ferritic welds which undergo a solid-state phase transformation upon welding, Zr2.5Nb0.9Hf welds also develop high tensile residual stresses in the heat-affected zone whereas the stresses closer to the weld tip are reduced by the effects of the β → α solid-state phase transformation.

  17. A new method of welding with trailing peening for controlling welding stress and distortion

    Institute of Scientific and Technical Information of China (English)

    Zhao Jianguo; Li Jianchang; Hao Jianjun; Ma Yuejin; Jiang Hui; Wang Huiqiang

    2009-01-01

    In order to control welding stress and distortion, a new welding with trailing peening method based on the electromagnetic hammer was developed. This method uses the idea of constant frequency pulse width modulation for designing the control circuit of peening force and peening frequency. The peening force can be adjusted between 0 and 1 000 N and the peening frequency ranges from 0 to 25 Hz. Peening force is applied to the weld metal and the weld toe during the welding by peening head. The experiments show that the method is portable and flexible, and it can adjust the distribution state of welding residual stress, making grain refinement. When the peening force is changed to 700 N and the peening frequency to 3 Hz, both the transverse and longitudinal residual stresses will drop obviously.

  18. CAP1400核电站接管和安全端焊接变形与残余应力研究%Investigation on Welding Deformation and Residual Stress for Nozzle Safe-End Welded Joints of CAP1400 Nuclear Power Plant

    Institute of Scientific and Technical Information of China (English)

    谷雨; 张俊宝; 余燕

    2016-01-01

    Welding deformation and residual stress was studied for the mockup of the nozzle safe-end weld joint of CAP1400 nuclear power plant.It is showed that welding deformation occurs mainly in the welding initial stage.When the thickness of the deposited metal was a quarter of the joint,the amount of deforma-tion was about 3 mm,while 4.5 mm when the nozzle safe-end joint welding was completed.Both the cir-cumferential and axial welding residual stress are tensile stress through the whole welding joint.Max weld-ing residual stress is located in the heat affected zone.It is showed the max residual stress is mainly oc-curred near the fusion line between butt welds and buttering,as high as 500 MPa.%系统研究了 CAP1400核电站接管和安全端模拟件焊接变形与残余应力分布特点。接管和安全端在焊接过程中焊接变形主要集中于焊接的初始阶段,焊接1/4厚度时,变形量为3 mm 左右,焊接完成后,焊缝收缩量高达4.5 mm。盲孔法测试结果表明,在整个接管和安全端焊接接头内,环向与轴向焊接残余应力均为拉应力。焊接残余应力的最大值位于安全端镍基堆焊层与对接焊缝熔合线附近,测试结果达到500 MPa。

  19. VIBRATORY STRESS, SOLIDIFICATION AND MICROSTRUCTURE OF WELDMENTS UNDER VIBRATORY WELDING CONDITION-A REVIEW

    Directory of Open Access Journals (Sweden)

    AKANKSHA VERMA,

    2011-06-01

    Full Text Available Welding processes induce a state of residual stress into materials and jobs. This poses a series of problems, in terms of dimensional stability, corrosion cracking, reduced fatigue life and structural integrity . Thermal cycle produced near weld line generates residual stress and inhomogeneous plastic deformation in weldments. Understanding of grain nucleation and grain growth becomes necessary that are influenced under welding conditions. After completion of nucleation, the solidification process will continue with nucleus growth .With vibratory weld conditioning, the enhancement of weld metal microstructure can be achieved. The mechanical properties, level of residual stresses, and deformation can also be affected . Structural changes of the welds prepared under vibratory conditions affects the mechanical properties of the welds. The vibration duringwelding benefits energy absorbed in impact toughness test of weld metal and improves fracture behavior. This paper presents the microstructure, solidification behaviour and residual stress relaxation under vibratory welding condition.

  20. The use of neutron diffraction for the determination of the in-depth residual stresses profile in weld coatings; A utilizacao da difracao de neutroes na determinacao do perfil de tensoes residuais em revestimentos por soldadura

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Maria Jose; Batista, A.C.; Nobre, J.P. [Universidade de Coimbra (Portugal). Dept. de Fisica. Centro de Estudos de Materiais por Difraccao de Raios X (CEMDRX); Loureiro, Altino [Universidade de Coimbra (Portugal). Dept. de Engenharia Mecanica. Centro de Engenharia Mecanica (CEMUC); Kornmeier, Joana R., E-mail: mjvaz@fe.up.pt [Technische Universitaet Muenchen, Garching (Germany). FRM II

    2013-04-15

    The neutron diffraction is a non-destructive technique, particularly suitable for the analysis of residual stress fields in welds. The technique is used in this article to study ferritic samples, coated by submerged arc welding using stainless steel filler metals. This procedure is often used for manufacturing process equipment for chemical and nuclear industries, for ease of implementation and economic reasons. The main disadvantage of that processes is the cracking phenomenon that often occurs at the interface between the base material and coatings, which can be minimized by performing post-weld stress relief heat treatments. The samples analyzed in this study were made of carbon steel plates, coated by submerged arc welding two types of stainless steel filler metals. For the first layer was used one EN 12 072 - S 2 U 23 12 electrode, while for the second and third layers were used an EN 12 072 - 19 12 3 S L electrode. After cladding, the samples were submitted to a post-weld heat treatment for 1 hour at 620 deg C. The residual stress profiles obtained by neutron diffraction evidence the relaxation of residual stress given by the heat treatment. (author)

  1. 焊趾TIG熔修对7075铝合金接头残余应力的影响%The Influence of Welded Toe TIG Dressing To the Residual Stress of 7075 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    许志安

    2013-01-01

    In order to research the influence of welded toe TIG dressing process on 7075 aluminum alloy T-joint, we use ABAQUS finite element method to establish physical model and analyse the residual stress distribution of welded toe. The residual stresses of welded toe were also measured by using the blind-hole method. The results indicate that after TTG dressing, the longitudinal residual stresses in welded toe of steel joint are gradually transited from tensile residual stresses to compressive ones, and there is no significant change for transverse residual stresses. The TIG dressing treatment can not only improve the residual stress distribution, but also make the surface of welded toe transferred smoothly, which is useful for the increase of fatigue strength.%为了研究焊趾TIG重熔处理工艺对7075铝合金T型接头残余应力状态的影响,采用ABAQUS有限元法建立有限元物理模型分析了焊趾部位残余应力分布状态,并采用盲孔实验法测定了焊趾部位的残余应力值.结果表明,经TIG重熔处理后,焊趾部位的残余应力值有所降低,纵向残余应力由焊态的拉伸应力状态过渡到重熔后的压缩应力状态;横向残余应力为压缩应力状态,应力值略有降低.焊趾TIG重熔工艺不仅改善了焊趾部位的残余应力状态,同时使焊趾部位表面圆滑过渡,从而有利于疲劳强度的提高.

  2. An Evaluation on the Effect of Residual Stress and Phase Transformation Improvement by Welding in Half Nozzle Repair Method of BMI Nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Park, Giyeol; Lee, Sangho; Kim, Taeryong [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2015-10-15

    In this study, it is evaluated that the effect of Pad welding for the Half Nozzle Repair method in the BMI the main instrument of NPP using SYSWELD which is the weld analysis code. BMI (Bottom Mounted Instrumentation) Nozzle is less sensitive to PWSCC generation of Alloy 600 material because the operation temperature is in the relatively low temperature region. But, it is very important to ensure the maintenance of the technical preparation for the damage because Nozzle is installed at reactor bottom head which is not possible to replace. A damage of Reactor Vessel BMI Nozzle under operation was confirmed as No.1 and No.46 Nozzle was observed to find acid precipitate while inspecting the reactor vessel bottom head of STP unit 1 in April 2003. Thus maintenance technology was developed such as Half Nozzle Repair in order to prevent damage of J-Groove welding including BMI Nozzle. In case of J-Groove welding, after cutting J-Groove satisfied the condition required by welding geometry design, new Nozzle of Alloy 690 material is inserted. And then welding applied for welding process parameters is performed when welding procedure applied for Alloy 52 weld filler metal is satisfied. The result of evaluation can be obtained as the following. 1) In order to prevent PWSCC of the BMI nozzle, the Half Nozzle Repair method was performed. As the result, the material Alloy 690 which has the strong corrosion resistance, one of the main factors of PWSCC, was replaced to prevent PWSCC. However, the higher tensile stress, another factor of PWSCC, than yield strength (350MPa) was occurred for Alloy 690 in the inner diameter of the nozzle contacting with the primary water in terms of the Hoop Stress. But compared to the yield strength, it cannot be seen much difference, so the prevention of PWSCC can be estimated. However, additional mechanical surface enhancing procedure such as pinning after welding is required so as to reduce the high tensile stress of the entire welding portion. 2

  3. Finite element analysis of metallurgical phase transformations in AA 6056-T4 and their effects upon the residual stress and distortion states of a laser welded T-joint

    Energy Technology Data Exchange (ETDEWEB)

    Zain-ul-abdein, Muhammad [Universite de Lyon, CNRS, INSA-Lyon, LaMCoS UMR5259, F-69621 (France); Nelias, Daniel, E-mail: daniel.nelias@insa-lyon.f [Universite de Lyon, CNRS, INSA-Lyon, LaMCoS UMR5259, F-69621 (France); Jullien, Jean-Francois [Universite de Lyon, CNRS, INSA-Lyon, LaMCoS UMR5259, F-69621 (France); Boitout, Frederic; Dischert, Luc; Noe, Xavier [ESI Group Le Recamier 70, rue Robert 69458 Lyon Cedex 06 (France)

    2011-01-15

    Aircraft industry makes extensive use of aluminium alloy AA 6056-T4 in the fabrication of fuselage panels using laser beam welding technique. Since high temperatures are involved in the manufacturing process, the precipitation/dissolution occurrences are expected as solid state phase transformations. These transformations are likely to affect the residual distortion and stress states of the component. The present work investigates the effect of metallurgical phase transformations upon the residual stresses and distortions induced by laser beam welding in a T-joint configuration using the finite element method. Two separate models were studied using different finite element codes, where the first one describes a thermo-mechanical analysis using Abaqus; while the second one discusses a thermo-metallo-mechanical analysis using Sysweld. A comparative analysis of experimentally validated finite element models has been performed and the residual stress states with and without the metallurgical phase transformations are predicted. The results show that the inclusion of phase transformations has a negligible effect on predicted distortions, which are in agreement with the experimental data, but an effect on predicted residual stresses, although the experimentally measured residual stresses are not available to support the analyses.

  4. Empleo de explosivos en el alivio de tensiones residuales de la zona de influencia térmica de uniones soldadas Use of explosives in the reduction of residual stresses in the heated zone of welded unions

    Directory of Open Access Journals (Sweden)

    J. L. Garcia-Jacomino

    2009-06-01

    Full Text Available En el trabajo es estudiado el efecto del tratamiento con explosivos sobre las tensiones residuales de uniones soldadas de aceros al carbono. Se analizan dos modos de disposición de la carga explosiva (disposición lineal y disposición sinusoidal. Como resultado se obtiene que el tratamiento con explosivo por cualquiera de los dos métodos de colocación de carga ofrece un alivio de tensiones en el entorno de 50 - 60 %, demostrándose así la viabilidad del método para aumentar la fiabilidad de las uniones soldadas. Se concluye también que la disposición sinusoidal resulta más ventajosa al requerir de menor cantidad de carga explosiva.In this paper, the effect of explosive charges as a method to reduce the residual stresses in the heated zone of welded unions was studied. A comparative analysis of two geometries of the explosive charge applied on welded unions was made: linear and sinusoidal. The comparative results obtained before and after the explosive treatment demonstrate its effectiveness by the reduction of the residual stresses. Residual stress reduction ranged in the order of 50 and 60%, confirming that explosive treatment offers a viable solution to extend the life of the welded unions.

  5. Modelling the residual stresses and microstructural evolution in Friction Stir Welding of AA2024-T3 including the Wagner-Kampmann precipitation model

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Hattel, Jesper Henri

    In this work, a numerical finite element model for friction stir welding of 2024-T3 aluminum alloy, consisting of a heat transfer analysis and a sequentially coupled quasi-static stress analysis is proposed. Metallurgical softening of the material is properly considered and included...

  6. Avaliação das tensões residuais em tubos de pequeno diâmetro soldados pelo processo TIG orbital Residual stress evaluation in small diameter pipes welded using orbital TIG process

    Directory of Open Access Journals (Sweden)

    George Luiz Gomes de Oliveira

    2009-06-01

    Full Text Available O objetivo desse trabalho é avaliar o efeito da soldagem TIG orbital sobre o nível de tensões residuais da junta, sobre a microestrutura resultante e sobre o aspecto superficial do cordão de solda, considerando os efeitos da energia de soldagem, do número de passes e do tipo de pulsação (corrente e rotação em tubos de pequeno diâmetro e contribuir para a análise de decisões de se aplicar ou não testes hidrostáticos ou TTPS. Os corpos de prova soldados com diferentes níveis de energia, pulsação e número de passes foram submetidos à medição de tensões residuais em um difratômetro de Raios-X. As amostras também foram submetidas a análises metalográficas. Conclui-se que as tensões residuais na superfície externa dos tubos são de caráter compressivo. O nível de tensões residuais nos tubos cai com o aumento da energia de soldagem e é menor para tubos soldados utilizando pulsação do que com os soldados sem pulsação e, para esse trabalho, não foi influenciado substancialmente pelo número de passes. As amostras analisadas apresentaram microestruturas convencionais para o aço empregado.This work aims in evaluate the effect of orbital TIG welding on the joint's residual stress level, the final microstructure and the superficial aspect of the weld filet, observing the welding energy, number of passes and the type of pulsation effects in small diameter pipes. The test specimens were welded with different energy, pulsation and number of passes levels and after that it were submitted to residual stress measurement in a X-Ray diffractometer, samples were extracted from the test specimens and it were submitted to metallographic analysis. The ending of this work is that: residual stress in the pipes outer surface are compressive, residual stress level in pipes goes down with increasing welding energy, it is smaller for pipes welded with pulsation and in this work it were not effectively influenced by number of passes

  7. U肋加劲板焊接残余应力数值模拟分析%NUMERICAL ANALYSIS OF WELDING RESIDUAL STRESS OF U-RIB STIFFENED PLATE

    Institute of Scientific and Technical Information of China (English)

    赵秋; 吴冲

    2012-01-01

    通过数值模拟和实验方法对U肋加劲板焊接残余应力进行了估算和分析,建立了三维热弹塑性有限元模型,采用生死单元法模拟焊缝填充和焊接热输入过程,实现了整个焊接过程中的动态应力和变形变化,得到了U肋加劲板的焊接温度场和应力场,分析了u肋加劲板的焊接残余应力分布,并与残余应力测试试验结果比较。结果显示:u肋加劲板近焊缝区残余拉应力达到材料屈服强度,母板远离焊缝区残余压应力平均值约为材料屈服强度的0.2倍,其分布趋势与实验测试得到的残余应力分布比较接近,证明了所采用的焊接数值模拟方法的正确性。%In order to take into account the change of stress and deformation during the whole process of welding and the thermal field distribution of a U-rib stiffened plate, a thermal elastic-plastic FEM model was adopted and element birth and death was used to simulate the weld seam fill-in and heat input. And the residual stress distribution was investigated by numerical simulations and experiments. The comparison of numerical analyses and experimental results of distribution and magnitude of residual stress showed that residual stress near the weld seam is close to material yielding stress, the average value of the residual stress far from weld seam on the mother board was around 0.2 time of material yielding stress. The residual stress distribution tendency derived from numerical simulation was close to the experiment result, which proved the validity of the numerical simulation.

  8. Analytical Method for Reduction of Residual Stress Using Low Frequency and Ultrasonic Vibrations

    Science.gov (United States)

    Aoki, Shigeru; Kurita, Katsumi; Koshimizu, Shigeomi; Nishimura, Tadashi; Hiroi, Tetsumaro; Hirai, Seiji

    Welding is widely used for construction of many structures. It is well known that residual stress is generated near the bead because of locally given heat. Tensile residual stress on the surface degrades fatigue strength. On the other hand, welding is used for repair of mold and die. In this case, reduction of residual stress is required because of protection from crack of welded part in mold and die. In this paper, a new method for reduction of residual stress of welded joint is proposed for repair welding of mold and die. In this method, low frequency and ultrasonic vibrations are used during welding. Thick plates are used as specimens of mold and die. Residual stresses are reduced when low frequency and ultrasonic vibrations are used during welding. Experimental results are examined by simulation method using an analytical model. One mass model considering plastic deformation is used as an analytical model. Experimental results are demonstrated by simulation method.

  9. 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.

  10. Formation of welding residual stresses in low transformation temperature (LTT materials Tensões residuais de soldagem em materias de baixa temperatura de transformação (BTT

    Directory of Open Access Journals (Sweden)

    Thomas Kannengiesser

    2009-03-01

    Full Text Available For the safety and cost efficiency of welded high-strength steel structures, precise knowledge of the level and distribution of welding- and cooling-specific stresses and residual stresses is essential, since they exert a decisive influence on strength, crack resistance, and finally on the bearable service load. This paper presents innovative filler materials, of which the phase transformation temperature was deliberately adjusted via the chemical composition. The transformation behaviour of these martensitic Low Transformation Temperature (LTT- filler materials shows direct effects on the local residual stresses in the weld and the HAZ. These effects can purposefully be exploited to counteract the thermally induced shrinkage of the material and to produce significant compressive residual stresses in the weld. Comparative welding experiments were carried out on 690 MPa high-strength base materials using various LTT-filler materials. High energy synchrotron radiation was used for residual stress measurement. Particularly the use of high energy synchrotron radiation makes it possible to detect the residual stress condition fast without destruction of material. Thereby, residual stress depth gradients can be determined simultaneously without removing material. In steel, gradients of up to 150 µm can be resolved in such a way. Furthermore, the application of high energy radiation permits determination of residual stresses of any available residual austenite contents. Results show significant dependence of transformation temperatures on the resulting residual stress level and distribution.Para a segurança e eficiência do custo de estruturas soldadas de aço de alta resistência, um conhecimento preciso do nível e distribuição das tensões residuais de soldagem é essencial pois estas exercem uma influência decisiva na resistência à fissuração e na carga suportada em serviço. Este artigo apresenta metais de adição inovativos nos quais a

  11. Systematic Review of Ultrasonic Impact Treatment Parameters on Residual Stresses of Welded Non-Sensitized Versus Sensitized Aluminum-Magnesium

    Science.gov (United States)

    2015-03-01

    plastic deformation UIT ultrasonic impact treatment UTS ultimate tensile strength wt% weight percent XRD x-ray diffractometry xv THIS PAGE...steel Excellent corrosion resistance Weldability Ease of forming, bending and machining High thermal and electrical conductivity Recyclable Non...stresses are internal to the material and are generated when a material undergoes plastic deformation (fabrication or joining of materials), large

  12. Numerical modeling of AA2024-T3 friction stir welding process for residual stress evaluation, including softening effects

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Carlone, Pierpaolo; Palazzo, Gaetano S.;

    2014-01-01

    In the present paper, a numerical finite element model of the precipitation hardenable AA2024-T3 aluminum alloy, consisting of a heat transfer analysis based on the Thermal Pseudo Mechanical model for heat generation, and a sequentially coupled quasi-static stress analysis is proposed. Metallurgi...

  13. Numerical simulation of stress and deformation of in-service welding onto gas pipeline

    Institute of Scientific and Technical Information of China (English)

    Chen Yuhua; Wang Yong; Han Bin; Wang Zhengfang

    2006-01-01

    SYSWELD was used to simulate in-service welding process of gas pipeline of X70 pipeline steel. Welding thermal cycle, stress and deformation of in-service welded joint were studied. The results show that peak temperature of coarse grain heat-affected zone (CGHAZ) of in-service welding onto gas pipeline is the same with routine welding, but t8/5 ,t8/3 and t8/1 decrease at certain degree. For the zone near welded seam, axial stress and hoop stress in the inner pipe wall are compressive stress when welding source passes through the cross-section that is studied, but residual axial stress and residual hoop stress after welded are all tensile stress. Transient deformation and residual deformation are all convex deformation compared with the original pipe diameter size. Deformation achieves maximum when welding thermal source passes through the cross-section that is studied and then decreases during the cooling process after welding.

  14. Influence of welding-induced residual stress on underwater acoustic radiation of ring stiffened cylindrical shell%焊接残余应力对环肋圆柱壳水下声辐射影响研究

    Institute of Scientific and Technical Information of China (English)

    李磊鑫; 刘勇; 陈炉云

    2016-01-01

    文章重点研究了焊接残余应力对环肋圆柱壳水下声辐射的影响。通过运用热弹塑性有限元法数值模拟环肋圆柱壳对接焊接过程,得到厚板环形焊缝的三维残余应力场和应变场,然后对含有残余应力的环肋圆柱壳动力特性进行研究,并运用有限元法和边界元法分析了低频激励下其水下声辐射的特点。研究结果表明焊接残余应力对环肋圆柱壳声辐射有较明显的影响,不仅使声辐射功率曲线和外场声压曲线向低频移动,而且使在大部分激励频率上含有焊接残余应力结构的声辐射功率和外场声压均大于无焊接残余应力结构。%This paper focuses on the influence of welding residual stress on underwater acoustic radiation of ring stiffened cylindrical shell. The thermal elastic-plastic finite element method is used to simulate ring stiffened cylindrical shell butt welding process and to calculate the three-dimensional welding-induced residual stress and strain field. And the dynamic characteristic of ring stiffened cylindrical shell with residu-al stress is investigated. Finally, its acoustic radiation is solved by combining direct boundary element method with finite element method. The results show that residual stress has a significant impact on underwater a-coustic radiation of ring stiffened cylindrical shell under low frequency excitation. It makes acoustic radia-tion power and sound pressure curve integrally move toward lower frequency, and makes acoustic radiation power and sound pressure increase at most excitation frequencies comparing with structure without residual stress.

  15. Finite element analysis of residual stress of welded joints modified by spray fusing%喷熔修形后的焊接接头残余应力有限元分析

    Institute of Scientific and Technical Information of China (English)

    赵小辉; 王东坡; 邓彩艳

    2011-01-01

    In this paper,Ni60 alloy powders were used to improve the fatigue strength of cruciform joints of Q235B through modification of spray fusing.Test results showed that the section shape of welded joints can be improved by flame spraying.High cycle fatigue test results showed that 2×106 cycles offset fatigue strength of the welded joints spray fused by Ni60 increased by 64.5%.The thermal stress was simulated by the finite element(ANSYS12.0) based on spraying parameters.Simulation results show that,the residual stress of substrate material and coating layer is still tensile stress and compared with as-welded joints,the magnitude of tensile stress decreases slightly.The residual stress of as-welded and coating surface is about 238 MPa and 182 MPa respectively.Thus,the residual stress is decreased by 24% after spray fusing.%采用Ni60合金粉末对Q235B钢焊态十字接头进行了氧—乙炔火焰喷熔处理,同时进行了高频疲劳试验.分析认为喷熔修形改善了焊接接头的几何外形.喷熔修形态十字接头在2×106循环周次下的疲劳强度比原始焊态提高了64.5%.基于氧—乙炔火焰喷熔工艺参数,采用ANSYS12.0软件对喷熔过程进行了热-应力耦合的有限元模拟,分析认为,焊缝和涂层表面的残余应力仍为拉应力,但是残余拉应力的大小和喷熔前原始焊态接头表层的残余拉应力相比略微减小.原始焊态接头表层的拉应力约为238 MPa,喷熔修形后喷熔层表面的残余拉应力约

  16. Effect of Welding Residual Stress and Deformation in CO2 Gas Shielded Welded Joints of Q345D Steel%残余应力和变形在Q345D钢CO2气体保护焊接接头中的分布

    Institute of Scientific and Technical Information of China (English)

    王玉仓; 王向杰

    2012-01-01

    基于有限元分析软件,采用数值模拟方法分析了Q345D低合金高强钢T型接头双面焊接残余应力和变形的分布.数值分析时,选择双椭球焊接热源模型,考虑了材料热物理性能与温度的非线性关系,以及相变潜热对温度场的影响,重点研究了焊缝及临近焊缝区域焊接残余应力和变形的分布特征,并进行了理论分析.研究结果可为同类素材的实际焊接提供理论借鉴.%Based on the finite element analysis software, the distribution of welding residual stress and deformation in CO2 gas shielded double-welded Q345D low alloy high strength steel T-joint were analyzed by numerical simulation. In simulation, a double ellipsoid welding heat source model was employed, and the nonlinear relationship between temperature and thermal physical properties of material, as well as the influences of latent heat on the temperature field were taken into account After the simulation, the distribution characteristics of welding residual stresses and deformation in and near the weld region were focused on. The findings provide theoretical references for the actual welding of similar material.

  17. The Effects of Welding Residual Stress on the Structure' s Vibration and Acoustic Radiation%焊缝对环肋圆柱壳振动声辐射的影响

    Institute of Scientific and Technical Information of China (English)

    杨念; 易宏; 刘勇

    2014-01-01

    This paper studies the effect of welding residual stress on the structure's vibration and acoustic radiation,by choosing the natural frequency as the intermediate quantity. First,the relationship between welding residual stress and natural frequency is analyzed and validated with the experimental method;the result shows that the welding residual stress directly affects the natural frequency. Then,the theoretical derivation about the sensitivity between the natural frequency and acoustic radiated power is conducted, which indicates that the natural frequency serves as an important variable to the acoustic radiated power. In conclusion,the welding residual stress is closely related to the structure's acoustic radiated power and should not be ignored when performing dynamic analysis.%将结构固有频率作为中间变量,研究焊接残余应力、结构固有频率和结构声辐射特性之间的关系。首先,分析焊接残余应力与结构固有频率之间的关系,并通过实验进行验证,结果显示焊接残余应力使结构固有频率发生了显著改变。然后,对固有频率—声辐射功率的灵敏度进行理论推导,并运用有限元法结合边界元法建立数值模型,计算该模型在指定范围内的固有频率—声辐射功率灵敏度,结果证明结构声辐射功率会随着固有频率的变化而发生显著变化。最后,综合分析焊接残余应力与结构声辐射之间的关系。结果表明,研究复杂结构的振动声辐射等动力学特性时,焊接残余应力是不能忽视的影响因素。

  18. Stress Engineering of Multi-pass Welds of Structural Steel to Enhance Structural Integrity

    Science.gov (United States)

    Ganguly, Supriyo; Sule, Jibrin; Yakubu, Mustapha Y.

    2016-08-01

    In multi-pass welding, the weld metal and the associated heat-affected zone are subjected to repeated thermal cycling from successive deposition of filler metals. The thermal straining results into multi-mode deformation of the weld metal which causes a variably distributed residual stress field through the thickness and across the weld of a multi-pass weldment. In addition to this, the as-welded fusion zone microstructure shows dendritic formation of grains and segregation of alloying element. This may result in formation of micro-corrosion cells and the problem would aggravate in case of highly alloyed materials. Local mechanical tensioning is an effective way of elimination of the weld tensile residual stress. It has been shown that application of cold rolling is capable not only of removing the residual stress, but depending on its magnitude it may also form beneficial compressive stress state. Multi-pass structural steel welds used as structural alloy in general engineering and structural applications. Such alloys are subjected to severe in-service degradation mechanisms e.g., corrosion and stress corrosion cracking. Welds and the locked-in residual stress in the welded area often initiate the defect which finally results in failure. In the present study, a multi-pass structural steel weld metal was first subjected to post-weld cold rolling which was followed by controlled heating by a fiber laser. Cold straining resulted in redistribution of the internal stress through the thickness and controlled laser processing helps in reforming of the grain structure. However, even with controlled laser, processing the residual stress is reinstated. Therefore, a strategy has been adopted to roll the metal post-laser processing so as to obtain a complete stress-free and recrystallized microstructure.

  19. Residual stresses within sprayed coatings

    Institute of Scientific and Technical Information of China (English)

    JIANG Yi; XU Bin-shi; WANG Hai-dou

    2005-01-01

    Some important developments of residual stress researches for coating-based systems were studied. The following topics were included the sources of residual stresses in coatings: error analysis of Stoney's equation in the curvature method used for the measurement of coating residual stress, the modeling of residual stress and some analytical models for predicting the residual stresses in coatings. These topics should provide some important insights for the fail-safe design of the coating-based systems.

  20. Laser ultrasonic diagnostics of residual stress.

    Science.gov (United States)

    Karabutov, Alexander; Devichensky, Anton; Ivochkin, Alexander; Lyamshev, Michael; Pelivanov, Ivan; Rohadgi, Upendra; Solomatin, Vladimir; Subudhi, Manomohan

    2008-11-01

    Ultrasonic NDE is one of the most promising methods for non-destructive diagnostics of residual stresses. However the relative change of sound velocity, which is directly proportional to applied stress, is extremely small. An initial stress of 100 MPa produces the result of deltaV/V approximately 10(-4). Therefore measurements must be performed with high precision. The required accuracy can be achieved with laser-exited ultrasonic transients. Radiation from a Nd-YAG laser (pulse duration 7 ns, pulse energy 100 microJ) was absorbed by the surface of the sample. The exited ultrasonic transients resembled the form of laser pulses. A specially designed optoacoustic transducer was used both for the excitation and detecting of the ultrasonic pulses. The wide frequency band of the piezodetector made it possible to achieve the time-of-flight measurements with an accuracy of about 0.5 ns. This technique was used for measuring of plane residual stress in welds and for in-depth testing of subsurface residual stresses in metals. Plane stress distribution for welded metallic plates of different thicknesses (2-8 mm) and the subsurface stress distribution for titanium and nickel alloys were obtained. The results of conventional testing are in good agreement with the laser ultrasonic method.

  1. Definition of Locked-up Stresses around a Rectilinear Welding Seam

    Science.gov (United States)

    Velikanov, N. L.; Koryagin, S. I.; Sharkov, O. V.

    2016-04-01

    In article one of the ways of modelling of the locked-up stresses caused by imposing of a welding seam in a plate is described. These stresses are caused by residual deformations of welding seams. In the settlement scheme the welding seam is presented in the form of an element by the thickness equal to the thickness of a plate, inserted in it with a longitudinal and cross-section tightness. The field of locked-up stresses around the welding seam experiences longitudinal and cross-section shrinkage under cooling and it is defined in work with the use of complex potentials of the theory of elasticity.

  2. Numerical analysis of thermal stresses in welded joint smade of steels X20 and X22

    OpenAIRE

    Mladenović Saša M.; Šijački-Zeravčić Vera M.; Bakić Gordana M.; Lozanović-Šajić Jasmina V.; Rakin Marko P.; Đurđević Andrijana A.; Đukić Miloš B.

    2014-01-01

    Stress calculation of steam pipeline is presented, focused on the welded joint. Numerical calculation was performed using the finite element method to obtain stress distribution in the welded joint made while replacing the valve chamber. Dissimilar materials were used, namely steel 10CrMoV9-10 according to EN 10216-2 for the valve chamber, the rest of steam pipeline was steel X20, whereas the transition piece material was steel X22. Residual stresses were c...

  3. Measurement of residual stresses using fracture mechanics weight functions

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Y. [Bettis Atomic Power Laboratory, West Mifflin, PA (United States)

    2001-07-01

    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)

  4. Effects of cutting and specimen size on neutron measurement of residual stresses

    Science.gov (United States)

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

    2010-11-01

    To perform neutron residual stress measurements it is often necessary to cut samples to a manageable size. The effects of cutting a girth welded pipe were investigated with analytical methods and finite element analysis. The effect of cutting on measured stresses was calculated. A simplified method of modelling residual stresses in welds, "chill modelling", is introduced. In ring slitting a cut is made in the axial direction and the deformation is maeesured. The change in elastic stress can be calculated and added to neutron diffraction measurements made on a cut ring to calculate the original stresses. Residual stress measurements were performed to validate the ring slitting correction using ANSTO's residual stress diffractometer Kowari.

  5. Numerical analysis of thermal stresses in welded joint smade of steels X20 and X22

    Directory of Open Access Journals (Sweden)

    Mladenović Saša M.

    2014-01-01

    Full Text Available Stress calculation of steam pipeline is presented, focused on the welded joint. Numerical calculation was performed using the finite element method to obtain stress distribution in the welded joint made while replacing the valve chamber. Dissimilar materials were used, namely steel 10CrMoV9-10 according to EN 10216-2 for the valve chamber, the rest of steam pipeline was steel X20, whereas the transition piece material was steel X22. Residual stresses were calculated, in addition to design stresses, indicating critical regions and necessity for post-weld heat treatment.

  6. Residual Stress in Welded Beryllium Ring by Neutron Diffraction and Finite Element Modeling%铍环焊接残余应力的中子衍射测试与有限元分析

    Institute of Scientific and Technical Information of China (English)

    董平; 王虹; 李建; 孙光爱; 廖哲; 杨江荣

    2015-01-01

    利用稳态堆上的中子衍射应力谱仪开展了铍环激光焊接后的残余应力测试.先进行铍材中子衍射应力测试的参数及其优化研究 ,在固定堆功率、衍射晶面和规范体积的条件下 ,选取测试时间分别为600 s和6 000 s进行铍环上同一点的中子衍射峰的重复性测试 ,结果表明 ,后者测试铍材应变的统计误差仅为前者的1/3 ,其标准偏差约为1. 10 × 10-5 .取后者测试时间作为优化参数 ,对铍环焊缝附近轴向应变和环向应变方向的中子衍射峰进行测试 ,获得两个方向的残余应变分布 ,进一步计算出焊接残余应力分布.对铍环激光焊接过程的温度场和应力场进行三维有限元数值模拟 ,将有限元计算得到的铍环焊缝附近中间壁厚处的残余应力和应变与中子衍射测试结果进行对比 ,结果表明二者分布规律较为一致 .%The residual stresses in a laser welded beryllium ring were measured using neutron diffraction stress instrument on a stable reactor .Firstly ,the parameters of neu-tron diffraction stress measurement for beryllium were studied and optimized .Keeping the reactor power ,diffraction plane and gauge volume fixed ,the neutron diffraction curves at a point in the beryllium ring were measured repeatedly by using the measure time of 600 s and 6 000 s ,then the statistical errors for the strains of beryllium were deduced ,w hich for the later is only 1/3 of the former ,and the standard error is about 1.10 × 10-5 .The neutron diffraction curves along axial strain and hoop strain near the weld line of the beryllium ring were measured using the optimized time 6 000 s .Both of the residual strains in the beryllium ring were obtained ,and the residual stresses were also calculated . The temperature and stress fields in the beryllium ring during laser welding process were simulated by using a 3D finite element model . The computed residual stress and strain at the middle of thick wall in

  7. Nondestructive Testing Residual Stress Using Ultrasonic Critical Refracted Longitudinal Wave

    Science.gov (United States)

    Xu, Chunguang; Song, Wentao; Pan, Qinxue; Li, Huanxin; Liu, Shuai

    Residual stress has significant impacts on the performance of the mechanical components, especially on its strength, fatigue life and corrosion resistance and dimensional stability. Based on theory of acoustoelasticity, the testing principle of ultrasonic LCR wave method is analyzed. The testing system of residual stress is build. The method of calibration of stress coefficient is proposed in order to improve the detection precision. At last, through experiments and applications on residual stress testing of oil pipeline weld joint, vehicle's torsion shaft, glass and ceramics, gear tooth root, and so on, the result show that it deserved to be studied deeply on application and popularization of ultrasonic LCR wave method.

  8. RAPID AND NONDESTRUCTIVE MEASUREMENT SYSTEM FOR WELDING RESDIUAL STRESS BY ULTRASONIC METHOD

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Traditional methods of residual stress measurement are generally destructive or semi-destructive, as well as expensive, time-consuming and complex to implement. With the new development of welded structure, traditional methods can not satisfy the need of full life task management. So the acoustical theory is introduced, since the ultrasonic technique provides a useful nondestructive tool in the evaluation of stresses. In this study an ultrasonic stress measurement experimental installation is established, which consists of a special transducer, a signal emission unit and a signal recipient processing unit. Longitudinal critically refracted wave is selected as the measurement wave mode. The supporting software is programmed by Labview software. The longitudinal residual stress and transverse residual stress of twin wire welded plate are measured by this installment, in which the measuring process is real-time, quick and nondestructive. The experiment results indicate that the system can satisfy the need of life evaluation for welded structure. The system is light and portable.

  9. ANSYS Simulation of Residual Strains in Butt-welded Joints

    Directory of Open Access Journals (Sweden)

    A. Atroshenko

    2014-07-01

    Full Text Available The effect of thermal-strain cycle on residual strains in thin-walled circular seams of cylindrical shells using TIG butt welds was studied. Estimates were calculated using numerical modelling. The structure was made of corrosion-resistant austenitic steels.

  10. 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.

  11. Residual stress state in titanium alloy remelted using GTAW method

    Directory of Open Access Journals (Sweden)

    A. Dudek

    2009-04-01

    Full Text Available Test materials comprised two-phase titanium alloy Ti6Al4V (Grade5. The surface of the tested alloy was remelted by means of TIG welding method using variable current-voltage parameters. The investigations aimed to determine surface geometry and residual stresses in the remelted surface layer in the investigated alloy.

  12. Three dimension simulation analysis of the interpass stress and deformation during multipass welding

    Institute of Scientific and Technical Information of China (English)

    Zhang Huajun; Zhang Guangjun; Zhang Xiulan; Cai Chunbo; Gao Hongming

    2008-01-01

    It has been widely studied about the final residual stress and deformation in multipass welding of thick weldments. But there is a lack of a clear understanding of the interrelationship of interpass stress and deformation during multipass welding. In this study, a three dimension numerical model of a sixteen-pass double V-groove welded joint with 50 mm plate is developed to compute the stress field and deformation by using multiple CPU parallel processing technology. The following factors such as the non-linear of temperature, heat radiation, filling of material step by step and so on are considered. Distribution and evolution law of welding stress in the transverse and longitudinal section is analyzed in this paper, and the interpass stresses are studied also. At the same time the evolution course of angular deformation amount is analyzed, and the experimental results show that the calculated results accord with the measured results of angular deformation.

  13. Distribution of Inherent Strains and Residual Stresses in Medium Thickness Plate Weldment

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A fundamental theory for the analysis of residual weldingstresses and deformation based on the inherent strain distribution along the welded joint is introduced. Distribution of inherent strains and longitudinal residual stresses in medium thickness plate weldment is calculated and analyzed.A new method of calculating inherent strains and longitudinal residual stresses is proposed.

  14. Investigation on residual stress in Q460 high strength steel welded box sections%Q460高强钢焊接箱形截面残余应力研究

    Institute of Scientific and Technical Information of China (English)

    班慧勇; 施刚; 石永久; 王元清

    2013-01-01

    In order to investigate the residual stress in Q460 high strength steel welded box sections, an experimental program including 6 section specimens with various dimensions was described in which the sectioning method was employed. The residual stress distribution over the entire section was obtained through original data. The effects from the plate width-thickness ratio and plate thickness as well as the human error and interaction between component plates were clarified. It is indicated that the compressive residual stress is correlated with sectional dimension while the tensile one has no clear relation with the sectional dimension. The human error of measurements is quite small, and residual stress equilibrium within each component plate is found. Finally, a distribution model and calculation formulae were established which took into account the effects from sectional dimensions and had a good agreement with test results.%为研究国产Q460高强钢焊接箱形截面的残余应力分布规律,采用分割法对6个不同截面尺寸的试件进行了试验研究.基于测量数据,得到了不同试件全截面残余应力分布,研究了板件宽厚比、板件厚度等几何尺寸对残余应力的影响以及测量过程中人为产生的误差、截面板件间残余应力的相互影响及自平衡性等.试验结果表明:残余压应力与截面尺寸直接相关,残余拉应力与截面尺寸关系不大;采用分割法测量时人为操作产生的误差很小;截面4块板件的残余应力能够分别满足自平衡条件.提出了适用于Q460高强钢焊接箱形截面的残余应力分布模型和计算式,该模型能够准确反映截面尺寸的影响,且与试验结果吻合良好.

  15. Measurement of the stressed state of welded joints in the NPP process components and circulation pipelines based on acoustoelasticity theory

    Directory of Open Access Journals (Sweden)

    A.I. Trofimov

    2016-09-01

    Full Text Available The paper presents the results of a theoretical justification and an experimental research for a method to measure the stressed state of welded joints in the nuclear power plant (NPP process components and circulation pipelines based on acoustoelasticity theory, as well as for ways to implement them technically. Devices for measuring the stressed state of welded joints in the NPP process components and circulation pipelines based on acoustoelasticity theory allow online measurement of residual stresses along the weld height and detection of crack formation points. The use of such devices will enable early crack detection in welded joints for an increased safety of the NPP operation.

  16. Welding Stress and Welding Distortion of 6061 Aluminium Alloy Thin Plate%6061铝合金薄板焊接应力与焊接变形

    Institute of Scientific and Technical Information of China (English)

    陈丽华; 封艳

    2013-01-01

    the relationship between the plate size, welding current, welding voltage and welding stress, the welding distortion for 6061 aluminum alloy sheet TIG welding is studied. With the increase of welding current, welding voltage,aluminium alloy of the longitudinal and lateral contraction deformation increase; With the increase of the length of the plate, due to the much more constraint, the plate of the longitudinal residual deformation decrease,for the bending stress in thickness direction increases,the transverse deformation increases. Residual stress of welding is tensile, and the parent metal close to weld is compressive stress, and the rest of the parent metal is tensile stress, the more the welding energy is, the greater the residual stress.%研究了6061铝合金薄板TIG焊焊接应力、焊接变形与焊接电流、焊接电压和板材尺寸的关系.随着焊接线能量的增加,铝合金的纵向和横向收缩变形增加;随着板的长度的增加,由于约束增加,板的纵向残余变形减少,厚度方向的抗弯增大,横向变形增大.板焊后,焊缝处受拉应力,而紧靠焊缝的母材处却受压应力,其余部分受拉应力且焊接线能量越大,残余应力越大.

  17. Numerical and Experimental Analyses of Residual Stresses in

    DEFF Research Database (Denmark)

    Hansen, Jan Langkjær; Hattel, Jesper; Lorentzen, Torben

    1999-01-01

    Butt-welding in one pass with SMAW of two 10mm mild steel plates is investigated. In order to predict the residual stress fields associated with the welding procedure, a finite element model in 3D has been developed in ABAQUS. This model applies a sequential thermal and mechanical numerical...... analysis. In order to evaluate and refine the model parameters for the thermal analysis, the numerical results from this analysis are compared with experimental measurements of the temperature. To evaluate the predicted stress/strain fields, the mechanical model has been validated experimentally. This has...

  18. Interferometric Measurement Of Residual Stress

    Science.gov (United States)

    Danyluk, Steven; Andonian, A. T.

    1990-01-01

    Stress averaged through thickness of plate measured nondestructively. Theory of elasticity combined with laser interferometric technique into technique for measurement of residual stresses in solid objects - usually in thin, nominally-flat plates. Measurements particularly useful in inspection of wafers of single-crystal silicon for making solar cells or integrated circuits, because stresses remaining after crystal-growing process cause buckling or fracture. Used to predict deflections of plates caused by known applied loads under specified boundary condition, or to infer applied loads that cause known deflections. Also used to relate known deflections to residual stresses equivalent to stresses produced by fictitious applied loads.

  19. Influence of residual stresses on failure pressure of cylindrical pressure vessels

    Institute of Scientific and Technical Information of China (English)

    M. Jeyakumar; T. Christopher

    2013-01-01

    The utilization of pressure vessels in aerospace applications is manifold. In this work, finite element analysis (FEA) has been carried out using ANSYS software package with 2D axisym-metric model to access the failure pressure of cylindrical pressure vessel made of ASTM A36 carbon steel having weld-induced residual stresses. To find out the effect of residual stresses on failure pressure, first an elasto-plastic analysis is performed to find out the failure pressure of pressure vessel not having residual stresses. Then a thermo-mechanical finite element analysis is performed to assess the residual stresses developed in the pressure vessel during welding. Finally one more elasto-plastic analysis is performed to assess the effect of residual stresses on failure pressure of the pressure vessel having residual stresses. This analysis indicates reduction in the failure pressure due to unfavorable residual stresses.

  20. Numerical analysis of welded joint treated by explosion shock waves

    Institute of Scientific and Technical Information of China (English)

    GUAN Jianjun; CHEN Huaining

    2007-01-01

    This paper focuses on the simulation of welding residual stresses and the action of explosion shock waves on welding residual stresses. Firstly, the distributions of welding temperature field and residual stress on a butt joint were numerically simulated with the sequentially coupled method. Secondly, the effect of explosion shock waves, produced by plastic strip-like explosive, on welding residual stress distri-bution was predicted with coupled Lagrange-ALE algorithm.It was implicated that explosion treatment could effectively reduce welding residual stresses. The simulation work lays a foundation for the further research on the rule of explosion treatment's effect on welding residual stresses and the factors that may influence it.

  1. Measurement of Residual Stress Field of Hardfacing Metal with RE Oxide and Its Numerical Simulation

    Institute of Scientific and Technical Information of China (English)

    杨庆祥; 姚枚

    2003-01-01

    The temperature and residual stress fields of a medium-high carbon steel, welded by a cracking resistance electrode with rare earth (RE) oxide, were measured by thermo-vision analyzer and X-ray stress analyzer respectively. Meanwhile, the martensitic transformation temperatures of matrix, hard-face welding (hardfacing) metal welded by conventional hardfacing electrode and that welded by cracking resistance electrode with RE oxide were determined. According to the expe rimental data and the thermo-physical, mechanical parameters of materials, finite element method (FEM) of temperature and stress fields was established. In this FEM, the effect of martensitic transformation on residual stress of hardfacing metal of medium-high carbon steel was taken into account. The results show that, by adding RE oxide in the coat of hardfacing electrode, the martensitic trans formation temperature can be decreased, so that the residual tensile stress on the dangerous position can be decreased. Therefore, the cracking resistance of hardfacing metal can be improved.

  2. Electromechanical Apparatus Measures Residual Stress

    Science.gov (United States)

    Chern, Engmin J.; Flom, Yury

    1993-01-01

    Nondestructive test exploits relationship between stress and eddy-current-probe resistance. Yields data on residual stress or strain in metal tension/compression specimen (stress or strain remaining in specimen when no stress applied from without). Apparatus is assembly of commercial equipment: tension-or-compression testing machine, eddy-current probe, impedance gain-and-phase analyzer measuring impedance of probe coil, and desktop computer, which controls other equipment and processes data received from impedance gain-and-phase analyzer.

  3. Numerical simulation about the effect of fixture on the welding stress and distortion of thin aluminum plate joints

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effect of welding jig on the welding stress and buckling distortion of thin aluminum plate joints was simulated by finite element method (FEM). The results show that the restraint distance and the heat conduction ability of the fixture do have essential effects on the residual stress and distortion. The residual compressive stress and distortion will be increasing with the increase of the restraint distance, while the residual compressive stress and distortion will be decreasing with the increase of the heat conduction ability of the fixture.

  4. Simulation of multi-pass welding residual stress in thick plate based on ANSYS%基于ANSYS的厚板多道焊焊接残余应力模拟

    Institute of Scientific and Technical Information of China (English)

    张晓飞

    2012-01-01

    利用ANSYS参数化有限元分析APDL语言编制相关程序,对980钢平板对接焊的温度场及应力场进行模拟,为实际生产过程中分析焊接结构性能、优化焊接工艺提供了有效指导.%In this paper, using the ANSYS parametric finite element analysis of APDL language procedures, simulates the butt-welding thermal field and stress field on 980 sleel plate,as the actual production process analysis of welding structure properties, optimizing welding technology provides effective guidance.

  5. 摩托车后平叉CO2保护焊接过程残余应力和变形的有限元预测%Finite Element Prediction on Residual Stress and Deformation in CO2 Arc Welding of Motorcycle Rear Fork

    Institute of Scientific and Technical Information of China (English)

    夏成宇; 马健; 黄扬; 钱利勤

    2012-01-01

    Based on the finite element analysis theory of the welding process, taking into account of thermal physical properties the material changing with the temperature, convection and radiation heat transfer boundary conditions, a welding-specific finite element analysis software of SYSWELD was employed to simulate the CO2 protection welding process of motorcycle fork. Furthermore, the evolution of the transient temperature field was analyzed. The distribution of residual deformation and residual stress in welding structures at room temperature was predicted in theory.%基于焊接过程有限元分析理论,考虑材料随温度变化的热物理性能和对流、辐射换热边界条件,应用SYSWELD焊接专用有限元分析软件,对摩托车后平叉CO2保护焊接全过程进行了数值仿真,分析了焊接过程瞬态温度场的演变,预测了焊接结构冷却至室温状态时的残余变形和残余应力分布,并进行了理论分析.

  6. The influence of heat treatment by annealing on clad plates residual stresses

    Directory of Open Access Journals (Sweden)

    B. Mateša

    2011-10-01

    Full Text Available The influence of applied clad procedure as well as heat treatment by annealing (650 °C/2h on level and nature of residual stresses was researched. Three clad procedures are used i.e. hot rolling, submerged arc welding (SAW with strip electrode and explosion welding. The relaxed deformation measurement on clad plate surfaces was performed by applying centre-hole drilling method using special measuring electrical resistance strain gauges (rosettes. After performed measuring, size and nature of residual stresses were determined using analytical method. Depending of residual stresses on depth of drilled blind-hole is studied.

  7. A new nondestructive instrument for bulk residual stress measurement using tungsten kα1 X-ray

    Science.gov (United States)

    Ma, Ce; Dou, Zuo-yong; Chen, Li; Li, Yun; Tan, Xiao; Dong, Ping; Zhang, Jin; Zheng, Lin; Zhang, Peng-cheng

    2016-11-01

    We describe an experimental instrument used for measuring nondestructively the residual stress using short wavelength X-ray, tungsten kα1. By introducing a photon energy screening technology, the monochromatic X-ray diffraction of tungsten kα1 was realized using a CdTe detector. A high precision Huber goniometer is utilized in order to reduce the error in residual stress measurement. This paper summarizes the main performance of this instrument, measurement depth, stress error, as opposed to the neutron diffraction measurements of residual stress. Here, we demonstrate an application on the determination of residual stress in an aluminum alloy welded by the friction stir welding.

  8. The effect of hardening laws and thermal softening on modeling residual stresses in FSW of aluminum alloy 2024-T3

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Tutum, Cem Celal; Hattel, Jesper Henri;

    2013-01-01

    or kinematic hardening together with the metallurgical softening model were applied in order to give a first impression of the tendencies in residual stresses in friction stir welds when choosing different hardening and softening behaviors. Secondly, real friction stir butt welding of aluminum alloy 2024-T3...... were simulated and compared with experimentally obtained results for both temperatures and residual stresses (using the slitting method). The comparisons showed good agreement regarding temperatures whereas the residual stress comparisons indicated different sensitivities for the cold and hot welding...

  9. Stress Analysis and Evaluating of Stream Residual Tank

    Institute of Scientific and Technical Information of China (English)

    DAI; Shou-tong

    2013-01-01

    Entrusted by China Nuclear Engineer Lit.,we’ve analyzed and evaluated the stress of stream residual tank,one of the high level radioactive waste vitrification process equipments,which is classified asradiochemical ClassⅠ,anti-seismic TypeⅠ.The container consists of upper and bottom dished covers,barrel body,four cylinder shell supporting legs which are welded on the equipment’s foundation

  10. Prediction of residual stresses induced by TIG welding of a martensitic steel (X10CrMoVNb9-1); Prevision des contraintes residuelles induites par le soudage TIG d'un acier martensitique (X10CrMoVNb9-1)

    Energy Technology Data Exchange (ETDEWEB)

    Roux, G.M

    2007-11-15

    Within the frame of the development of very high temperature nuclear reactors (VHTR) with gas as heat transfer fluid, some technological challenges are to be faced because of these high temperatures, notably the selection of the material used for the reactor vessel and its welding process. This research thesis aims at developing and validating numerical tools and behaviour models for the thermal-metallurgical-mechanical simulation of the multi-pass TIG welding process. The first part describes the development of simple welding tests (Disk-Spot and Disk-Cycle), the use of temperature and displacement measurement during these tests, and deep residual stress measurements, as well as the identification of the thermal limit conditions for the Disk-Spot test. It then discusses the choice and the identification of the thermal-metallurgical-mechanical behaviour model, with a particular attention to phase transformations and to their coupling with thermal and mechanical aspects. Experimental and simulation results are compared, notably in terms of residual stresses. The numerical implementation of the behaviour model and its integration into the CAST3M finite element software are also described.

  11. Neutron residual stress measurements in linepipe

    Energy Technology Data Exchange (ETDEWEB)

    Law, Michael [ANTSO, PMB1 Menai, NSW, 2234 (Australia)]. E-mail: michael.law@ansto.gov.au; Gnaepel-Herold, Thomas [Department of Materials Science and Engineering, NCNR and University of Maryland (United States); Luzin, Vladimir [Department of Materials Science and Engineering, NCNR and University of Maryland (United States); Bowie, Graham [cNCNR and State University of New York at Stoneybrook (United States): Blue Scope Steel (Australia)

    2006-11-15

    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.

  12. Mitigation of Tensile Weld Stresses in Alloy 22 Using Laser Peening

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H L; Evans, K J; Hackel, L A; Rankin, J E; Yamamoto, R M; Demma, A G; Dewald, A T; Lee, M J; Hill, M R

    2002-11-27

    The goal of the Yucca Mountain Project (YMP) is safe permanent disposal of high-level nuclear waste. One of the many technical challenges to this plan is the design of the Engineered Barrier System (EBS) including the waste package that will contain the radioactive waste. One potential failure mode of the waste package is stress corrosion cracking (SCC), which occurs when three criteria simultaneously exist. These criteria are a potentially corrosive environment, a material susceptible to SCC, and the presence of tensile residual stresses at the surface of the material. While many design decisions have been made to attempt to minimize the occurrence of the first two conditions, it is necessary to control the third condition, the presence of tensile residual stresses. These stresses occur as a result of a variety of manufacturing techniques, including welding. While most of the residual stresses due to the welding of the waste package can be mitigated through solution heat-treating, the final closure weld, which occurs after the radioactive waste has been placed in the waste package, must be treated to eliminate the presence of tensile residual stress near the surface. Laser peening is a commercially proven technology that has been shown to create compressive residual stress in both unstressed materials, as well as materials containing tensile surface residual stresses generated by welding. Lawrence Livermore National Laboratory (LLNL) has developed the laser peening process and the associated hardware for use by the YMP. Upon completion of the testing and engineering phases, LLNL will transfer the laser peening technology to U.S. industry and assist DOE in developing vendors to supply production units to be installed at the YMP facilities. The overall testing effort is divided into-two phases. Phase I of this project consisted of a study into the effectiveness of laser peening in generating compressive stress in small Alloy 22 base metal coupons and converting

  13. The influence of the weld toe grinding and wig remelting weld toe rehabilitation techniques, on variable stresses, in case of cross fillet welds, reinforced with additional welding rows

    Directory of Open Access Journals (Sweden)

    Babis Claudiu

    2017-01-01

    Full Text Available Variable stresses where the load value varies between a maximum and a minimum value, or varies the position in time, cause after accumulating a large number of load cycles in those structures, the emergence of drug fatigue. Fatigue is characterized by failure on values of the applied stress from the load cycles, below the material flow, values which in case of static stress would not have caused problems. Knowing that the variable stressed structures are sensitive to stress concentrators, the paper aims to highlight the influence of two techniques to reduce stress concentrator weld toe grinding and WIG remelting weld toe, on the behavior of variable tensile test of cross corner welded specimens, reinforced with additional welding rows.

  14. Relief of Residual Stresses in 800 MPa Grade High Strength Steel Weldments by Explosion Treatment and its Effect on Mechanical Properties

    Institute of Scientific and Technical Information of China (English)

    Changzhong WU; Huaining CHEN; Jing CHEN; Quanhong LIN; Jianjun GUAN

    2006-01-01

    The explosion treatment technique has been used in the relief of residual stresses in 800 MPa grade high strength steel manual welded joints. The residual stresses on surface and through thickness of the weldment were measured for both as-welded and explosion-treated sample, the mechanical properties of welded joints under different conditions were also tested. The effect of explosion treatment on the fracture toughness of materials with a residual defect was investigated by crack opening displacement (COD) test. The results show that explosion treatment can reduce not only the surface residual stress but also the residual stress through thickness in the welded joints. The effect of explosion treatment on the mechanical properties and a residual defect in welded joint were inconspicuous.

  15. 超声冲击对海洋工程大厚度高强钢焊接残余应力的影响%Effect of ultrasonic impact treatment on residual stress of large-thickness and high-strength steel welding structure in offshore engineering

    Institute of Scientific and Technical Information of China (English)

    朱海洋; 刘川; 邹家生

    2015-01-01

    Large-thickness and high-strength steel welding joints for offshore engineering are treated by ultrasonic impact treatment ( UIT) on weld and local parent material .X-ray diffraction ( XRD) and hole-drilling method are used to measure the as-welded stress and the stress after UIT .The effect of UIT on welding residual stress and the appropriate UIT strength are studied .Research results show that the as-welded residual stresses are sig-nificantly reduced after UIT , the as-welded tensile stresses within treated area are converted into compressive stresses, and the compressive stresses are uniform , the average value of compressive stress is 0.50~0.80 times nominal yield strength of the parent material in UIT area by XRD and 1.10~1.30 times by hole-drilling method:For an impact strength of 10 s/cm2 or 20 s/cm2 , the similar compressive stress values occur in the impacted area of EQ47 weld joint, the magnitude of longitudinal stress is similar to that of the transverse stress , and the effect of 20 s/cm2 is better than that of 10 s/cm2 .%对海洋工程大厚度高强钢焊接结构焊后焊缝及母材进行局部超声冲击处理,采用X射线衍射法和小孔法测试冲击前后的残余应力,分析超声冲击工艺对焊接残余应力的影响.研究结果表明:大厚度高强钢焊接结构经覆盖焊缝及母材局部超声冲击处理后,焊接残余应力显著降低,冲击区域拉应力全部转化为压应力,压应力大小均匀,XRD测试压应力均值达到母材理论屈服强度的0.50~0.80倍,小孔法测试压应力均值达到母材理论屈服强度的1.10~1.30倍;EQ47拘束态高强钢焊接结构分别采用冲击强度10 s/cm2与20 s/cm2冲击后,冲击区域形成的压应力基本一致,纵向应力与横向应力大小接近,20 s/cm2冲击强度下纵向应力与横向应力接近水平优于10 s/cm2.

  16. Ares I-X Upper Stage Simulator Residual Stress Analysis

    Science.gov (United States)

    Raju, Ivatury S.; Brust, Frederick W.; Phillips, Dawn R.; Cheston, Derrick

    2008-01-01

    The structural analyses described in the present report were performed in support of the NASA Engineering and Safety Center (NESC) Critical Initial Flaw Size (CIFS) assessment for the Ares I-X Upper Stage Simulator (USS) common shell segment. An independent assessment was conducted to determine the critical initial flaw size (CIFS) for the flange-to-skin weld in the Ares I-X Upper Stage Simulator (USS). The Ares system of space launch vehicles is the US National Aeronautics and Space Administration s plan for replacement of the aging space shuttle. The new Ares space launch system is somewhat of a combination of the space shuttle system and the Saturn launch vehicles used prior to the shuttle. Here, a series of weld analyses are performed to determine the residual stresses in a critical region of the USS. Weld residual stresses both increase constraint and mean stress thereby having an important effect on fatigue and fracture life. The results of this effort served as one of the critical load inputs required to perform a CIFS assessment of the same segment.

  17. Residual stresses of thin, short rectangular plates

    Science.gov (United States)

    Andonian, A. T.; Danyluk, S.

    1985-01-01

    The analysis of the residual stresses in thin, short rectangular plates is presented. The analysis is used in conjunction with a shadow moire interferometry technique by which residual stresses are obtained over a large spatial area from a strain measurement. The technique and analysis are applied to a residual stress measurement of polycrystalline silicon sheet grown by the edge-defined film growth technique.

  18. Evaluation of near-surface stress distributions in dissimilar welded joint by scanning acoustic microscopy.

    Science.gov (United States)

    Kwak, Dong Ryul; Yoshida, Sanichiro; Sasaki, Tomohiro; Todd, Judith A; Park, Ik Keun

    2016-04-01

    This paper presents the results from a set of experiments designed to ultrasonically measure the near surface stresses distributed within a dissimilar metal welded plate. A scanning acoustic microscope (SAM), with a tone-burst ultrasonic wave frequency of 200 MHz, was used for the measurement of near surface stresses in the dissimilar welded plate between 304 stainless steel and low carbon steel. For quantitative data acquisition such as leaky surface acoustic wave (leaky SAW) velocity measurement, a point focus acoustic lens of frequency 200 MHz was used and the leaky SAW velocities within the specimen were precisely measured. The distributions of the surface acoustic wave velocities change according to the near-surface stresses within the joint. A three dimensional (3D) finite element simulation was carried out to predict numerically the stress distributions and compare with the experimental results. The experiment and FE simulation results for the dissimilar welded plate showed good agreement. This research demonstrates that a combination of FE simulation and ultrasonic stress measurements using SAW velocity distributions appear promising for determining welding residual stresses in dissimilar material joints.

  19. 振动时效在大型焊接结构件中的应用%Application of Stress Relief by Vibration on Large Welded Structure

    Institute of Scientific and Technical Information of China (English)

    杨新华; 杨国华

    2012-01-01

    The influences of VSR on welding residual stress were studied through measuring the welding residual stress of welding lines in the pre-weld and post-weld by blind-hole method, and the feasibility and effectiveness of VSR process was employed, which can provide technology reference for production of large welded structures.%通过盲孔法对轨道焊缝振动时效前后残余应力的测量对比,研究振动时效工艺对焊接残余应力的影响,总结振动时效(VSR)工艺的可行性和有效性,从而为大型焊接结构件的生产提供技术参考.

  20. Modeling of Residual Stresses In Toughened Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    2006-01-01

    -depth knowledge of the residual stresses in toughened glass near holes and edges where the total stress state is a combination of contact stresses and residual stresses. The present paper, presenting the derivation and results for a model predicting the residual stresses in a glass plate far from edges and holes......, is a step towards such a model. The model is based on the Instant Freeze concept with a few modifications. Current work, using a partial differential equation approach for the modeling and state-of-the-art in modeling residual stresses in glass is briefly presented, and a short description of the toughening...

  1. Effects of simulation parameters on residual stresses for laser shock peening finite element analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ju Hee [Korea Military Academy, Seoul (Korea, Republic of); Kim, Yun Jae [Korea University, Seoul (Korea, Republic of); Kim, Joung Soo [KAERI, Daejeon (Korea, Republic of)

    2013-07-15

    By using finite element analysis, we proposed an applicable finite element method of laser shock peening (LSP) and discussed various parameters, such as solution time, stability limit, dynamic yield stress, peak pressure, pressure pulse duration, laser spot size, and multiple LSP. The effects of parameters related to the finite element simulation of the LSP process on the residual stresses of 35CD4 30HRC steel alloy are discussed. Parametric sensitivity analyses were performed to establish the optimum processing variables of the LSP process. In addition, we evaluated the effects of initial residual stress, such as welding-induced residual stress field.

  2. Assessment of Residual Stresses in 3013 Inner and Outer Containers and Teardrop Samples

    Energy Technology Data Exchange (ETDEWEB)

    Stroud, Mary Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Prime, Michael Bruce [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); Clausen, Bjorn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Worl, Laura Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); DeWald, Adrian T. [Hill Engineering, LLC, Rancho Cordova, CA (United States)

    2015-12-08

    This report is an assessment performed by LANL that examines packaging for plutonium-bearing materials and the resilience of its design. This report discusses residual stresses in the 3013 outer, the SRS/Hanford and RFETS/LLNL inner containers, and teardrop samples used in studies to assess the potential for SCC in 3013 containers. Residual tensile stresses in the heat affected zones of the closure welds are of particular concern.

  3. USING LASER ULTRASONICS FOR NONDESTRUCTIVE RESIDUAL STRESS EVALUATION

    Institute of Scientific and Technical Information of China (English)

    贺玲凤; Shoichi Kobayashi

    2002-01-01

    A non-contact measuring technique of ultrasonic waves velocity is proposed, in which Rayleigh waves are detected by a laser Doppler velocimeter and the velocity is measured precisely by means of a sing-around unit and a digital oscilloscope. With the proposed technique, the acoustoelastic coefficient of Rayleigh waves in mild steel SS41 is obtained, which is in good agreement with that obtained by the contact method. Furthermore the non-contact technique is applied to evaluate the residual stress in a butt-welded steel plate, the result is reasonable.

  4. Thermal Residual Stresses in Multilayered Coatings

    Institute of Scientific and Technical Information of China (English)

    Xiancheng ZHANG; Binshi XU; Haidou WANG; Yixiong WU

    2005-01-01

    The mechanical integrity and reliability of coated devices are strongly affected by the residual stresses in thin films and coatings. However, due to the metallurgical complexity of materials, it is rather difficult to obtain a closed-form solution of residual stresses within multilayered coatings (e.g. functionally graded coatings, FGCs). In this paper,an analytical model is developed to predict the distribution of residual stresses within multilayered coatings. The advantage of this model is that the solution of residual stresses is independent of the number of layers. Specific results are obtained by calculating elastic thermal stresses in ZrO2/NiCoCrAIY FGCs, which consist of different material layers. Furthermore, the residual stress distribution near the edges and the stress-induced failure modes of coating are also analyzed. The topics discussed provide some insights into the development of a methodology for designing fail-safe coating systems.

  5. Cryogenic Treatment of Al-Li Alloys for Improved Weldability, Repairability, and Reduction of Residual Stresses

    Science.gov (United States)

    Malone, Tina W.; Graham, Benny F.; Gentz, Steven J. (Technical Monitor)

    2001-01-01

    Service performance has shown that cryogenic treatment of some metals provides improved strength, fatigue life, and wear resistance to the processed material. Effects such as these were initially discovered by NASA engineers while evaluating spacecraft that had returned from the cold vacuum of space. Factors such as high cost, poor repairability, and poor machinability are currently prohibitive for wide range use of some aerospace aluminum alloys. Application of a cryogenic treatment process to these alloys is expected provide improvements in weldability and weld properties coupled with a reduction in repairs resulting in a significant reduction in the cost to manufacture and life cycle cost of aerospace hardware. The primary purpose of this effort was to evaluate the effects of deep cryogenic treatment of some aluminum alloy plate products, welds, and weld repairs, and optimize a process for the treatment of these materials. The optimized process is being evaluated for improvements in properties of plate and welds, improvements in weldability and repairability of treated materials, and as an alternative technique for the reduction of residual stresses in repaired welds. This paper will present the results of testing and evaluation conducted in this effort. These results will include assessments of changes in strength, toughness, stress corrosion susceptability, weldability, repairability, and reduction in residual stresses of repaired welds.

  6. Modeling of residual stress mitigation in austenitic stainless steel pipe girth weldment

    Energy Technology Data Exchange (ETDEWEB)

    Li, M.; Atteridge, D.G.; Anderson, W.E. [Oregon Graduate Inst., Portland, OR (United States); West, S.L. [Westinghouse Savannah River Co., Aiken, SC (United States)

    1994-03-01

    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.

  7. Residual thermal stresses in injection molded products

    NARCIS (Netherlands)

    Zoetelief, W.F.; Douven, L.F.A.; Ingen Housz, A.J.

    1996-01-01

    Nonisothermal flow of a polymer melt in a cold mold cavity introduces stresses that are partly frozen-in during solidification. Flow-induced stresses cause anisotropy of mechanical, thermal, and optical properties, while the residual thermal stresses induce warpage and stress-cracking. In this study

  8. Residual stresses in injection molded products

    NARCIS (Netherlands)

    Jansen, K.M.B.

    2015-01-01

    During the molding process residual stresses are formed due to thermal contraction during cooling as well as the local pressure history during solidification. In this paper a simple analytical model is reviewed which relates residual stresses, product shrinkage as well as warpage to the temperature

  9. Residual stress distribution in rabbit limb bones.

    Science.gov (United States)

    Yamada, Satoshi; Tadano, Shigeru; Fujisaki, Kazuhiro

    2011-04-29

    The presence of the residual stresses in bone tissue has been noted and the authors have reported that there are residual stresses in bone tissue. The aim of our study is to measure the residual stress distribution in the cortical bone of the extremities of vertebrates and to describe the relationships with the osteon population density. The study used the rabbit limb bones (femur, tibia/fibula, humerus, and radius/ulna) and measured the residual stresses in the bone axial direction at anterior and posterior positions on the cortical surface. The osteons at the sections at the measurement positions were observed by microscopy. As a result, the average stresses at the hindlimb bones and the forelimb bones were 210 and 149 MPa, respectively. In the femur, humerus, and radius/ulna, the residual stresses at the anterior position were larger than those at the posterior position, while in the tibia, the stress at the posterior position was larger than that at the anterior position. Further, in the femur and humerus, the osteon population densities in the anterior positions were larger than those in the posterior positions. In the tibia, the osteon population density in the posterior position was larger than that in the anterior position. Therefore, tensile residual stresses were observed at every measurement position in the rabbit limb bones and the value of residual stress correlated with the osteon population density (r=0.55, P<0.01).

  10. A utilização da difração de neutrões na determinação do perfil de tensões residuais em revestimentos por soldadura The use of neutron diffraction for the determination of the in-depth residual stresses profile in weld coatings

    Directory of Open Access Journals (Sweden)

    Maria José Marques

    2013-06-01

    Full Text Available A técnica de difração de neutrões é usada neste artigo para estudar amostras ferríticas, revestidas comaços inoxidáveisausteníticos através de soldadura por arco submerso. Este procedimento é frequentemente usado no fabrico de equipamentos de processo para as indústrias química e nuclear, por facilidade de execução e razões económicas. A principal desvantagem deste processo de revestimento é a fissuração que frequentemente ocorre na interface material base/soldadura, potenciada pela presença de tensões residuais resultantes da operação de soldadura, a qual pode ser minimizada com a realização de tratamentos térmicos de relaxação de tensões. As amostras foram produzidas a partir de placas em aço ao carbono, tendo uma das superfícies sido revestida com dois tipos de aço inoxidável. Para a primeira camada foi usado um elétrodo EN 12072 - S 23 12 2 L e para a segunda e a terceira camadas foi usado um elétrodo EN 12072 - S 19 12 3 L. Após a soldadura, as amostras foram submetidas a um tratamento térmico de relaxação de tensões, durante 1 hora, à temperatura de 620ºC. Os perfis de tensões residuais obtidos por difração de neutrões evidenciam a relaxação de tensões residuais após o tratamento térmico realizado. A técnica de difração de neutrões revelou-se muito adequada na avaliação de tensões residuais neste tipo de ligações.The neutron diffraction is a non-destructive technique, particularly suitable for the analysis of residual stress fields in welds. The technique is used in this article to study ferritic samples, coated by submerged arc welding using stainless steel filler metals. This procedure is often used for manufacturing process equipment for chemical and nuclear industries, for ease of implementation and economic reasons. The main disadvantage of that processes is the cracking phenomenon that often occurs at the interface between the base material and coatings, which can be

  11. Dynamic residual stress in thermal sprayed coatings

    Institute of Scientific and Technical Information of China (English)

    Wang Zhiping; Yang Yuanyuan

    2005-01-01

    With the modified Almen method, the forming and development process of residual stress in a thermal sprayed coating has been obtained. The test results identify that the residual stress in a coating is depend on coating material properties, technique and coating thickness. The paper pays much attention to the hysteresis between the coating temperature and residual stress in the coating or between the applied stress and the strain of the coating, and confirms that the fact is resulted from the"Gas Fix" character of a thermal sprayed coating.

  12. Axial residual stresses in boron fibers

    Science.gov (United States)

    Behrendt, D. R.

    1978-01-01

    A method of measuring axial residual stresses in boron fibers is presented. With this method, the axial residual stress distribution as a function of radius is determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diam fibers are similar, being compressive at the surface and changing monotonically to a region of tensile stress within the boron. At approximately 25% of the original radius, the stress reaches a maximum tensile stress of about 860 MN sq m and then decreases to a compressive stress near the tungsten boride core. Data are presented for 203-micron diam B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102-micron diam B/W and boron on carbon (B/C) show that the residual stresses are similar in the outer regions of the fibers, but that large differences near and in the core are observed. Fracture of boron fibers is discussed.

  13. Modeling of Residual Stresses In Toughened Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    2006-01-01

    The motivation for this work is the need for more extended guidelines considering structural design of glass structures. Realistic models predicting the strength of bolted connections are a step towards improvement of such guidelines. Improvement of guidelines for bolted connections require in......-depth knowledge of the residual stresses in toughened glass near holes and edges where the total stress state is a combination of contact stresses and residual stresses. The present paper, presenting the derivation and results for a model predicting the residual stresses in a glass plate far from edges and holes......, is a step towards such a model. The model is based on the Instant Freeze concept with a few modifications. Current work, using a partial differential equation approach for the modeling and state-of-the-art in modeling residual stresses in glass is briefly presented, and a short description of the toughening...

  14. EFFECT OF MEAN STRESS ON FATIGUE PERFORMANCE OF WELDED JOINTS TREATED BY UPT

    Institute of Scientific and Technical Information of China (English)

    Wang Dongpo; Huo Lixing; Wang Ting; Li Jie; Zhang Yufeng

    2004-01-01

    The fatigue contrast tests of unload longitudinal direction corner joints as original welded and treated by ultrasonic peening of Q235B in various stress ratio are directed. The improvements of fatigue performance of unload longitudinal direction corner joints resulted by ultrasonic peening are studied. The effect pattern of stress ratio on fatigue performance of welded joints that are treated by ultrasonic peening is studied. As tests results indicate that: ① In the condition of stress ratio R= -1, the fatigue strength of specimen treated by ultrasonic peening is increased by 165% of that of the original welded specimen. And the fatigue life of specimen treated by ultrasonic peening is as much as 75~210 times of that of the latter. When R=0.1, the fatigue strength is increased by 87% and the fatigue life is extended by 21~29 times. When R= -0.5, the fatigue strength is increased by 123% and the fatigue life is extended by 42~59 times. When R=0.45, the fatigue strength is increased by 51% and the fatigue life is extended by 3~14 times. ② If the welded joints are treated by ultrasonic peening, the fatigue strength is no longer independent on the applied mean stress. The more the stress ratio R, the less the fatigue stress range which can be sustained by the joints is. ③ Whether the high value residual stress is in the joints or not, the dead load portion of the applied load must be considered in the design of the joints which should be treated by ultrasonic peening.

  15. SIMULATION OF VIBRATION STRESS RELIEF AFTER WELDING BASED ON FEM

    Institute of Scientific and Technical Information of China (English)

    X.C.Zhao; Y.D.Zhang; H.W.Zhang; Q.Wu

    2008-01-01

    A finite element model is developed for the simulation of vibration stress relief (VSR) after welding.For the nonresonant vibration,the reduction in stress strongly depends on the amplitude of vibration.For the resonant vibration,the vibration frequency is the key for stress relief.The vibration frequency should be close to the structure natural frequency for the desired vibration mode.Only small vibration amplitude is required,which will be amplified during vibration.Vibration time does not have a major impact on vibration stress relief.When the amplitude of vibration stress relief is large,the treatment will be more effective.

  16. Round robin analysis on stress intensity factor of inner surface cracks in welded stainless steel pipes

    Energy Technology Data Exchange (ETDEWEB)

    Han, Chang Gi; Chang, Yoon Suk [Dept. of Nuclear Engineering, College of Engineering, Kyung Hee University, Yongin (Korea, Republic of); Kim, Jong Sung [Dept. of Mechanical Engineering, Sunchon National University, Sunchon (Korea, Republic of); Kim, Maan Won [Central Research Institute, Korea Hydro and Nuclear Power Company, Daejeon (Korea, Republic of)

    2016-12-15

    Austenitic stainless steels (ASSs) are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs) were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

  17. Round Robin Analyses on Stress Intensity Factors of Inner Surface Cracks in Welded Stainless Steel Pipes

    Directory of Open Access Journals (Sweden)

    Chang-Gi Han

    2016-12-01

    Full Text Available Austenitic stainless steels (ASSs are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

  18. Recover the story of a component or the determination of the welding residual stresses; Parcourir l`histoire d`un composant ou la determination des contraintes residuelles de soudage

    Energy Technology Data Exchange (ETDEWEB)

    Genette, P. [Electricite de France (EDF), 69 - Villeurbanne (France). Service Etudes et Projets Thermiques et Nucleaires; Dupas, Ph. [Electricite de France, 77 - Moret sur Loing (France). Dept. Mecanique et Technologie des Composants; Waeckel, F. [Electricite de France (EDF), 92 - Clamart (France). Dept. Mecanique et Modeles Numerique

    1998-10-01

    Mechanical components in nuclear power plants can keep track of the welding processes they had undergone before to entrying into service. The memory of these past events can postpone or enhance possible damage phenomena on these components. Nowadays, numerical simulation software, such as the Code ASTER, enable to reproduce numerically these welding processes so that their mechanical consequences be retrieved. (authors)

  19. Characterization of the structural details of residual austenite in the weld metal of a 9Cr1MoNbV welded rotor

    Institute of Scientific and Technical Information of China (English)

    Xia Liu; Hui-jun Ji; Peng Liu; Peng Wang; Feng-gui Lu; Yu-lai Gao

    2014-01-01

    The existence of residual austenite in weld metal plays an important role in determining the properties and dimensional accuracy of welded rotors. An effective corrosive agent and the metallographic etching process were developed to clearly reveal the characteristics of residual austenite in the weld metal of a 9Cr1MoNbV welded rotor. Moreover, the details of the distribution, shape, length, length-to-width ratio, and the content of residual austenite were systematically characterized using the Image-Pro Plus image analysis software. The results revealed that the area fraction of residual austenite was approximately 6.3% in the observed weld seam; the average area, length, and length-to-width ratio of dispersed residual austenite were quantitatively evaluated to be (5.5 ± 0.1)μm2, (5.0 ± 0.1)μm, and (2.2 ± 0.1), re-spectively. The newly developed corrosive agent and etching method offer an appropriate approach to characterize residual austenite in the weld metal of welded rotors in detail.

  20. Reduction of longitudinal axial residual stresses in near-root region of circumferential joint of steam pipeline in technological way

    Directory of Open Access Journals (Sweden)

    V. M. Prokhorenko

    2013-10-01

    Full Text Available The paper proposes a variant for solving the problem of reduction of longitudinal residual stresses in near-root region of a circumferential welded joint of section of steam pipeline by FEM simulation of the stress-strain state of repaired section of a circumferential weld in the zone of lack of root penetration on a thin-wall shell of 89 mm diameter and 6 mm wall thickness from steel 20. The result of solving the problem is total distribution of stresses and residual plastic deformations in the repaired zone.

  1. Virtual Welded - Joint Design Integrating Advanced Materials and Processing Technology

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhishang; Ludewig, Howard W.; Babu, S. Suresh

    2005-06-30

    Virtual Welede-Joint Design, a systematic modeling approach, has been developed in this project to predict the relationship of welding process, microstructure, properties, residual stress, and the ultimate weld fatique strength. This systematic modeling approach was applied in the welding of high strength steel. A special welding wire was developed in this project to introduce compressive residual stress at weld toe. The results from both modeling and experiments demonstrated that more than 10x fatique life improvement can be acheived in high strength steel welds by the combination of compressive residual stress from the special welding wire and the desired weld bead shape from a unique welding process. The results indicate a technology breakthrough in the design of lightweight and high fatique performance welded structures using high strength steels.

  2. Residual Stress Analysis in Thick Uranium Films

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-12-06

    Residual stress analysis was performed on thick, 1.0 to 25 {micro}m, 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 (0-300V). 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.

  3. TIG-dressing of High Strength Butt Welded Connection. Part 2: Physical Testing and Modelling

    NARCIS (Netherlands)

    Van Es, S.H.J.; Kolstein, M.H.; Pijpers, R.J.M.; Bijlaard, F.S.K.

    2014-01-01

    Weld improvement techniques are aimed at reducing the notch effects of welds and generally focus on two aspects: a change of geometry of the weld toe and a change of the weld residual stresses. In this paper, fatigue tests are discussed, performed on butt welded specimens in steel grades ranging

  4. TIG-dressing of high strength butt welded connection - Part 2: physical testing and modelling

    NARCIS (Netherlands)

    Es, S.H.J. van; Kolstein, M.H.; Pijpers, R.J.M.; Bijlaard, F.S.K.

    2013-01-01

    Weld improvement techniques are aimed at reducing the notch effects of welds and generally focus on two aspects: a change of geometry of the weld toe and a change of the weld residual stresses. In this paper, fatigue tests are discussed, performed on butt welded specimens in steel grades ranging

  5. TIG-dressing of high strength butt welded connection - Part 2: physical testing and modelling

    NARCIS (Netherlands)

    Es, S.H.J. van; Kolstein, M.H.; Pijpers, R.J.M.; Bijlaard, F.S.K.

    2013-01-01

    Weld improvement techniques are aimed at reducing the notch effects of welds and generally focus on two aspects: a change of geometry of the weld toe and a change of the weld residual stresses. In this paper, fatigue tests are discussed, performed on butt welded specimens in steel grades ranging fro

  6. TIG-dressing of High Strength Butt Welded Connection. Part 2: Physical Testing and Modelling

    NARCIS (Netherlands)

    Van Es, S.H.J.; Kolstein, M.H.; Pijpers, R.J.M.; Bijlaard, F.S.K.

    2014-01-01

    Weld improvement techniques are aimed at reducing the notch effects of welds and generally focus on two aspects: a change of geometry of the weld toe and a change of the weld residual stresses. In this paper, fatigue tests are discussed, performed on butt welded specimens in steel grades ranging fro

  7. Experimental Study of Inducing Compressive Stress by Anti-welding Heating Treatment in a Thin Plate Weldment with Variant Temperatures

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Significant compressive stress may be induced in thin plate weldment by anti-welding heating treatment (AWHT)with a temperature difference above 350℃, and an interesting phenomenon of obvious residual stress reduction on non-treated surface was discovered. The method of AWHT has no great effect on the mechanical properties including hardness, strength and toughness of the metal material. The results in the paper prompt a possibility application in shipbuilding industry.

  8. 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.

  9. Residual stresses in rubber formed thermoplastic composites

    NARCIS (Netherlands)

    Wijskamp, Sebastiaan; Lamers, E.A.D.; Akkerman, Remko; Brucato, V.

    2003-01-01

    The rubber pressing process is applied for the rapid production of thermoplastic composite products. However, rubber pressed products show geometrical distortions, such as warpage, due to processinduced residual stresses. An experimental study is performed to measure the curvature after rubber

  10. 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...

  11. Measurment Of Residual Stress In Ferromagnetic Materials

    Science.gov (United States)

    Namkung, Min; Yost, William T.; Kushnick, Peter W.; Grainger, John L.

    1992-01-01

    Magnetoacoustic (MAC) and magnetoacoustic emission (MAE) techniques combined to provide complete characterization of residual stresses in ferromagnetic structural materials. Combination of MAC and MAE techniques makes it possible to characterize residual tension and compression without being limited by surface conditions and unavailability of calibration standards. Significant in field of characterization of materials as well as detection of fatigue failure.

  12. Measurment Of Residual Stress In Ferromagnetic Materials

    Science.gov (United States)

    Namkung, Min; Yost, William T.; Kushnick, Peter W.; Grainger, John L.

    1992-01-01

    Magnetoacoustic (MAC) and magnetoacoustic emission (MAE) techniques combined to provide complete characterization of residual stresses in ferromagnetic structural materials. Combination of MAC and MAE techniques makes it possible to characterize residual tension and compression without being limited by surface conditions and unavailability of calibration standards. Significant in field of characterization of materials as well as detection of fatigue failure.

  13. Welding technology for rails. Rail no setsugo gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Okumura, M.; Karimine, K. (Nippon Steel Corp., Tokyo (Japan)); Uchino, K.; Sugino, K. (Nippon Steel Corp., Kitakyushu, Fukuoka (Japan). Technical Research Inst. of Yawata Works); Ueyama, K. (JR Railway Technical Research Inst., Tokyo (Japan))

    1993-08-01

    The rail joining technology is indispensable for making long welded rails. Flush butt welding, gas welding, enclosed arc welding, and thermit welding are used properly as the welding methods. A method for improving the joint reliability by controlling the residual stress distribution of welded joint is investigated to prepare high carbon component weld metal similar to the rail. Problems with each of the welding methods and the newly developed technology to solve the problems are outlined. Composition of the coating is improved also, and a high C system welding rod is developed which has satisfactory weldability. High performance and high efficient new enclosed arc welding technology not available by now is developed which utilizes high carbon welding metal as a new EA welding work technology, and put to practical use. As a result of this study, useful guides are obtained for the establishment of satisfactory thermit welding technology. 17 refs., 16 figs., 1 tab.

  14. Compared FEM and neutron diffraction study of residual strains in Eurofer97 prototype laser welds for fusion reactor technology

    Energy Technology Data Exchange (ETDEWEB)

    Coppol, R. [ENEA - Casaccia, FPN, CP Roma (Italy); Asserin, O. [CEA Saclay, 91 - Gif sur Yvette (France); Hughes, D.J. [Institut Max von Laue - Paul Langevin, 38 - Grenoble (France)

    2007-07-01

    Full text of publication follows: A reliable characterization of residual strains and stresses is a crucial step in the development of high quality welds for Helium-Cooled-Lithium-Lead (HCLL) blanket modules for DEMO. This contribution will present the first results of a comparative study, carried out using Finite Element Model (FEM) calculations and neutron diffraction measurements to determine the strain and stress field in an Eurofer97 (9Cr, 0.01C, 1W, 0.2V Fe bal wt%) prototype laser weld. The neutron diffraction measurements were carried out at the SALSA diffractometer at the High Flux Reactor of the Institut Max von Laue-Paul Langevin, Grenoble, France. A diffracting volume of approximately 1 x 1 x 5 mm{sup 3} was defined, giving appropriate neutron counting times and allowing a significant comparison with the material volume sampled by FEM. The measurements were carried out at various distances from the weld and within the Heat Affected Zone (HAZ), where the analysis of the detected diffraction line-widths provides information on the metallurgic phases produced during the heat treatment. The neutron diffraction results are compared with the theoretical calculations in view of providing them with an experimental validation. (authors)

  15. Long-Term Stability of Residual Stress Improvement by Water Jet Peening Considering Working Processes.

    Science.gov (United States)

    Hashimoto, Tadafumi; Osawa, Yusuke; Itoh, Shinsuke; Mochizuki, Masahito; Nishimoto, Kazutoshi

    2013-06-01

    To prevent primary water stress corrosion cracking (PWSCC), water jet peening (WJP) has been used on the welds of Ni-based alloys in pressurized water reactors (PWRs). Before WJP, the welds are machined and buffed in order to conduct a penetrant test (PT) to verify the weld qualities to access, and microstructure evolution takes place in the target area due to the severe plastic deformation. The compressive residual stresses induced by WJP might be unstable under elevated temperatures because of the high dislocation density in the compressive stress layer. Therefore, the stability of the compressive residual stresses caused by WJP was investigated during long-term operation by considering the microstructure evolution due to the working processes. The following conclusions were made: The compressive residual stresses were slightly relaxed in the surface layers of the thermally aged specimens. There were no differences in the magnitude of the relaxation based on temperature or time. The compressive residual stresses induced by WJP were confirmed to remain stable under elevated temperatures. The stress relaxation at the surface followed the Johnson-Mehl equation, which states that stress relaxation can occur due to the recovery of severe plastic strain, since the estimated activation energy agrees very well with the self-diffusion energy for Ni. By utilizing the additivity rule, it was indicated that stress relaxation due to recovery is completed during the startup process. It was proposed that the long-term stability of WJP under elevated temperatures must be assessed based on compressive stresses with respect to the yield stress. Thermal elastic-plastic creep analysis was performed to predict the effect of creep strain. After 100 yr of simulated continuous operation at 80% capacity, there was little change in the WJP compressive stresses under an actual operating temperature of 623 K. Therefore, the long-term stability of WJP during actual operation was

  16. Prediction of vulnerable zones based on residual stress and microstructure in CMT welded aluminum alloy joint%基于残余应力和微观组织形貌的铝合金CMT焊接接头薄弱环节的预测

    Institute of Scientific and Technical Information of China (English)

    舒凤远; 田泽; 吕耀辉; 贺文雄; 吕飞洋; 林建军; 赵洪运; 徐滨士

    2015-01-01

    Numerical simulation and experimental results were employed for the identification of the most vulnerable zones in three-pass cold-metal-transferring (CMT) welded joint. The residual stress distribution in the joint was predicted by finite element (FE) method, while the structural morphology of distinctive zones was obtained through metallographic experiments. The highest principal stress made the symmetric face of the joint most sensitive to tensile cracks under service conditions. Whereas, the boundaries between the weld seam and the base plates were sensitive to cracks because the equivalent von Mises stress was the highest when the first interpass cooling was finished. The third weld pass and the inter-pass remelted zones exhibited the modest mechanical performances as a result of the coarse grain and coarse grain boundary, respectively. The most vulnerable zones were regarded to be the crossed parts between the zones identified by numerical and experimental methods.%采用数值模拟与实验相结合的方法预测3道冷金属过渡(CMT)焊接接头的薄弱环节。通过有限元方法预测焊接接头中残余应力的分布特征;通过金相实验获得焊接接头中不同特征区域的微观组织形貌特征。接头对称面上的最大主应力值最高,故该区域在服役过程中较易产生拉伸裂纹。第一次层间冷却结束后,焊缝金属与基板的交界面上因等效von-Mises应力最大而具有较高的裂纹敏感性。根据金相分析结果,第3道焊缝中晶粒最为粗大,而层间的熔合区则具有粗大的晶间析出物组织特征,两种现象均意味着较差的力学性能。焊接接头中最为薄弱的区域则位于分别通过数值方法和实验方法得出的薄弱区域的交叉区域。

  17. Avaliação do campo de tensões residuais por difração de raios - X utilizando o método do sen²ψ em revestimentos metálicos do aço inoxidável E308-L Evaluation of residual stress field by x-ray diffraction using the sen²ψ method on E308-L stainless steel weld overlays

    Directory of Open Access Journals (Sweden)

    Raphael. H. F. Melo

    2013-03-01

    Full Text Available A aplicação por soldagem de revestimentos metálicos de aços e ligas nobres resistentes à corrosão é uma alternativa bastante razoável economicamente frente à fabricação de componentes maciços nestas ligas. Entretanto há uma carência de informações sobre as alterações mecânico/metalúrgicas causadas pelos ciclos térmicos de soldagem quando da aplicação destes revestimentos, principalmente sobre a influência sobre o nível de tensões residuais , que é mister no entendimento do fenômeno da corrosão assistida por tensão. O objetivo deste trabalho foi avaliar o nível de tensões residuais superficiais em revestimentos do aço inoxidável AWS E308-L T-1 aplicados pelo processo de soldagem ao Arco Elétrico com Arame Tubular sobre chapas do aço ASTM A36. As medições das tensões residuais foram realizadas por um difratômetro portátil de raios - X na superfície dos revestimentos e os principais resultados obtidos foram que a natureza das tensões residuais na superfície dos revestimentos sempre se apresentou compressivas e não observou-se uma linearidade da magnitude das tensões residuais em função da energia de soldagem.The application of metal coatings by welding of steels and alloys resistant to corrosion is an alternative quite reasonable economically facing the manufacturing of solid components in these alloys. However there is a lack of information about the mechanical / metallurgical changes caused by thermal cycles of welding due to the application of these coatings, especially on the influence on the level of residual stresses, that it is essential to understand the phenomenon of stress-assisted corrosion. The aim of this study was to evaluate the level of the superficial residual stresses in coatings of AWS E308L T-1 stainless steel applied by the FCAW process on steel plates of ASTM A36. The measurements of residual stresses were performed by a portable X - ray diffractometer on the surface of the

  18. 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.

  19. Modeling Stress-Strain State in Butt-Welded Joints after TIG Welding

    Directory of Open Access Journals (Sweden)

    V. Atroshenko

    2015-09-01

    Full Text Available In this paper mathematical model was developed for definition of thermal-welding cycle influence on welding deformations distribution in flat samples of austenitic steels after TIG welding and developed recommendations to reduce the welding deformation on o the machinery for welding with a copper backing.

  20. Effect of residual stress on peak cap stress in arteries.

    Science.gov (United States)

    Vandiver, Rebecca

    2014-10-01

    Vulnerable plaques are a subset of atherosclerotic plaques that are prone to rupture when high stresses occur in the cap. The roles of residual stress, plaque morphology, and cap stiffness on the cap stress are not completely understood. Here, arteries are modeled within the framework of nonlinear elasticity as incompressible cylindrical structures that are residually stressed through differential growth. These structures are assumed to have a nonlinear, anisotropic, hyperelastic response to stresses in the media and adventitia layers and an isotropic response in the intima and necrotic layers. The effect of differential growth on the peak stress is explored in a simple, concentric geometry and it is shown that axial differential growth decreases the peak stress in the inner layer. Furthermore, morphological risk factors are explored. The peak stress in residually stressed cylinders is not greatly affected by changing the thickness of the intima. The thickness of the necrotic layer is shown to be the most important morphological feature that affects the peak stress in a residually stressed vessel.

  1. Residual stress measurements in carbon steel

    Science.gov (United States)

    Heyman, J. S.; Min, N.

    1986-01-01

    External dc magnetic field-induced changes in natural velocity of Rayleigh surface waves were measured in steel specimens under various stress conditions. The low field slopes of curves representing the fractional changes of natural velocity were proved to provide correct stress information in steels with different metallurgical properties. The slopes of curves under uniaxial compression, exceeding about one third of the yield stress, fell below zero in all the specimens when magnetized along the stress axis. The slopes under tension varied among different steels but remained positive in any circumstances. The stress effect was observed for both applied and residual stress. A physical interpretation of these results is given based on the stress-induced domain structure changes and the delta epsilon effect. Most importantly, it is found that the influence of detailed metallurgical properties cause only secondary effects on the obtained stress information.

  2. Numerical investigation on stress corrosion cracking behavior of dissimilar weld joints in pressurized water reactor plants

    Directory of Open Access Journals (Sweden)

    Lingyan Zhao

    2014-07-01

    Full Text Available There have been incidents recently where stress corrosion cracking (SCC observed in the dissimilar metal weld (DMW joints connecting the reactor pressure vessel (RPV nozzle with the hot leg pipe. Due to the complex microstructure and mechanical heterogeneity in the weld region, dissimilar metal weld joints are more susceptible to SCC than the bulk steels in the simulated high temperature water environment of pressurized water reactor (PWR. Tensile residual stress (RS, in addition to operating loads, has a great contribution to SCC crack growth. Limited experimental conditions, varied influence factors and diverging experimental data make it difficult to accurately predict the SCC behavior of DMW joints with complex geometry, material configuration, operating loads and crack shape. Based on the film slip/dissolution oxidation model and elastic-plastic finite element method (EPFEM, an approach is developed to quantitatively predict the SCC growth rate of a RPV outlet nozzle DMW joint. Moreover, this approach is expected to be a pre-analytical tool for SCC experiment of DMW joints in PWR primary water environment.

  3. Mechanically induced residual stresses: Modelling and characterisation

    Science.gov (United States)

    Stranart, Jean-Claude E.

    Accurate characterisation of residual stress represents a major challenge to the engineering community. This is because it is difficult to validate the measurement and the accuracy is doubtful. It is with this in mind that the current research program concerning the characterisation of mechanically induced residual stresses was undertaken. Specifically, the cold expansion of fastener holes and the shot peening treatment of aerospace alloys, aluminium 7075 and titanium Ti-6Al-4V, are considered. The objective of this study is to characterise residual stresses resulting from cold working using three powerful techniques. These are: (i) theoretical using three dimensional non-linear finite element modelling, (ii) semi-destructive using a modified incremental hole drilling technique and (iii) nondestructive using a newly developed guided wave method supplemented by traditional C-scan measurements. The three dimensional finite element results of both simultaneous and sequential cold expansion of two fastener holes revealed the importance of the separation distance, the expansion level and the loading history upon the development and growth of the plastic zone and unloading residual stresses. It further showed that the commonly adopted two dimensional finite element models are inaccurate and incapable of predicting these residual stresses. Similarly, the dynamic elasto-plastic finite element studies of shot peening showed that the depth of the compressed layer, surface and sub-surface residual stresses are significantly influenced by the shot characteristics. Furthermore, the results reveal that the separation distance between two simultaneously impacting shots governs the plastic zone development and its growth. In the semi-destructive incremental hole drilling technique, the accuracy of the newly developed calibration coefficients and measurement techniques were verified with a known stress field and the method was used to measure peening residual stresses. Unlike

  4. Study of residual stresses in tailor rolled blanked Al5J32-T4 sheets

    Institute of Scientific and Technical Information of China (English)

    KIM Dongok; KIM Jinpyeong; LEE Yong; KWAK Heeman; RYU Yongmun; HAN Beomsuck

    2006-01-01

    Several automotive parts such as door panels have been manufactured by using load-adapted blanks for crash optimization and weight minimization.Recently, Tailor Rolled Blanks (TRB) has been introduced to remove the disadvantages of a welding process which was used in joining panel components.TRB offers better structural design capabilities due to the seamless transitions on the panels with different thicknesses.In spite of the advantages of the process, TRB leaves internal stresses in the panel.This residual stresses lower the formability of Tailor Rolled Blanked (TRBed) parts and cause cracks near severe curvature during subsequent forming processes.In this research, the residual stresses of TRBed Al5J32-T4 sheets were studied by X-ray stress analysis, and also microstructure was observed along the rolling direction.In addition, heat treatment was done after TRB process in order to compare the residual stresses to that of the TRBed sheets before the heat treatment.

  5. Study of Residual Stresses and Distortion in Structural Weldments in High-Strength Steels.

    Science.gov (United States)

    1981-11-30

    and Cracking due to Stress Relieving Heat Treatment of HY80 Steel ", Welding in the World, 10 (1/2), 1972. -114- elastic-plastic and creep analysis...900°F (500C) is adequate. In these steels stress relief treatments are beneficial for the prevention of stress corrosion and reheat cracking . For...of * Contract NOO014-75-C-0469 (M.I.T. OSP #82558) STUDY OF RESIDUAL STRESSES AND DISTORTION IN - . -- ISTRUCTURAL WELT*IENTS IN HIGH-STRENGTH STEELS

  6. Microstructure and Residual Stress of Shot Coating

    Science.gov (United States)

    Itoh, Yoshiyasu; Suyama, Shoko; Fuse, Toshiaki

    A shot coating process for metalizing at the surface of ceramics has been newly developed as the shot peening treatment. However, microstructure and residual stress of shot coatings, which have an important effect on the adherent strength of coatings and the strength of ceramic substrates, have not always been clarified. An experimental investigation on the microstructure and residual stress was carried out for the shot coating of aluminum on zinc-oxide substrate by comparison with the atmospheric plasma sprayed aluminum coatings. As a result, low porosity, low oxide content and flat surface could be obtained from the aluminum coatings formed by shot coating process in comparison with the atmospheric plasma sprayed aluminum coatings. Also, it was confirmed by the X-ray diffraction technique that the residual stress of shot coated aluminum over zinc-oxide substrate was high compressive in comparison with the atmospheric plasma spraying process.

  7. Residual contact stresses in cryotechnical environments

    Science.gov (United States)

    Cretegny, J. F.; Demonicault, J. M.

    Two examples were chosen to show the use of residual stress measurements in the evaluation and comprehension of possible ruptures of parts subjected to the working conditions of cryogenic turbomachines which induce wear of the surfaces in dry contact. The examples concern the ball bearings and spline of the liquid hydrogen pump of the Vulcain engine to be used on Ariane 5. The Ariane program is introduced and tribological problems of the cryogenic technique are discussed. The utility of the residual stress measurements is assessed.

  8. Stellite failure on a P91 HP valve - failure investigation and modelling of residual stresses

    DEFF Research Database (Denmark)

    Thorborg, Jesper; Hald, John; Hattel, Jesper Henri

    2006-01-01

    The sequence of the primary welding process and the following secondary processes of machining, and heat treatment has been modelled to predict the residual conditions in a Stellite 6 overlay weld on a P91 steam turbine valve. The different process steps are coupled in order to transfer the resid......The sequence of the primary welding process and the following secondary processes of machining, and heat treatment has been modelled to predict the residual conditions in a Stellite 6 overlay weld on a P91 steam turbine valve. The different process steps are coupled in order to transfer...... temperature dependent. The welding process is modelled by adding material to the calculation domain, while the machining process is modelled by removing material from the calculation domain to redistribute the stress fields. An in-house iso-parametric FEM-code is used for the implementation of the material...... models and the discretization of the appropriate addition and removal of material. The return mapping algorithm is used for the time discretization of the time independent plasticity model, and a Norton’s power law model is used for the time dependent model. Results from the numerical calculations...

  9. Numerical stress analysis of crack at welded beam-to-column connection

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the past, brittle fracture of steel structure was reported rarely under earthquake. However, recent earthquakes, especially Northridge Earthquake (USA) and Hyogoken-Nanbu earthquake (Japan), astonished engineers in the field of construction. The experience from recent earthquakes of USA and Japan shows that brittle fracture of welded steel structure always starts from high stress zone with welded crack[1~5]. As backing bar for grooved weld on beam flange exists, artificial crack is formed because of lack-of-fusion at the root of flange weld. In this paper stress distribution of connection is computed with FEM, and stress concentration at the root of flange weld is also analyzed. Stress intensity factors (SIFs), KI, at the root of flange weld are computed in the method of fracture mechanics. The computation shows that stress intensity factor on bottom flange weld is obviously higher than that on top flange weld. It is proved by the fact that brittle fracture is liable to start at the root of bottom flange weld on actual earthquake[1,4]. Finally measures are brought forward to avoid fracture of weld structure against earthquake.

  10. Residual stresses in bilayer dental ceramics.

    Science.gov (United States)

    Taskonak, Burak; Mecholsky, John J; Anusavice, Kenneth J

    2005-06-01

    It is clinically observed that lithia-disilicate-based all-ceramic fixed partial dentures (FPD) can fail because of the fragmentation of the veneering material. The hypothesis of this study is that the global residual stresses within the surface of those veneered FPDs may be responsible for partial fragmentation of the veneering ceramic. Bilayer and monolithic ceramic composites were prepared using a lithia disilicate based (Li2OSiO2) glass-ceramic core and a glass veneer. A four-step fracture mechanics approach was used to analyze residual stress in bilayered all-ceramic FPDs. We found a statistically significant increase in the mean flexural strengths of bilayer specimens compared with monolithic glass specimens (p < or = 0.05). There was a statistically significant difference between the mean longitudinal and transverse indentation-induced crack sizes in bilayer specimens (p < or = 0.05), which indicates the existence of residual stress. Global residual stresses in the veneer layer, calculated using a fracture mechanics equation, were determined to be responsible for the increased strength and observed chipping, i.e., spallation in bilayer ceramic composites.

  11. Residual stress in high modulus carbon fibers

    Science.gov (United States)

    Chen, K. J.; Diefendorf, R. J.

    1982-01-01

    The modulus and residual strain in carbon fibers are measured by successively electrochemically milling away the fiber surface. Electrochemical etching is found to remove the carbon fiber surface very uniformly, in contrast to air and wet oxidation. The precision of fiber diameter measurements is improved by using a laser diffraction technique instead of optical methods. More precise diameter measurements reveal that past correlations of diameter and fiber modulus are largely measurement artifact. The moduli of most carbon fibers decrease after the outer layers of the fibers are removed. Owing to experimental difficulties, the moduli and strengths of the fibers at their centers are not determined, and moduli are estimated on the basis of microstructure. The calculated residual stresses are found to be insensitive to these moduli estimates as well as the exact form of regression equation used to describe the moduli and residual strain distributions. Axial compressive residual stresses are found to be very high for some higher modulus carbon fibers. It is pointed out that the compressive stress makes the fibers insensitive to surface flaws when loaded in tension but it may initiate failure by buckling when loaded in compression.

  12. Distribution of Longitudinal Inherent Strains in Multiple-passes Welding

    Institute of Scientific and Technical Information of China (English)

    Peng HE; Jiuhai ZHANG; Toshio Terasaki; Testuya Akiyama

    2001-01-01

    A fundamental theory for the analysis of residual welding stresses and deformation based on the inherent strain distribution along the welded joint is introduced. The computing method of distribution of longitudinal inherent strains in multiple-passes welding in heavy plate weldment is proposed. Distribution of longitudinal inherent strains in one-pass welding and two-passes welding are compared and analyzed. The effect of cutting on inherent strain is discussed.

  13. Reduction of Residual Stress in Low Alloy Steel with Magnetic Treatment in Different Directions

    Institute of Scientific and Technical Information of China (English)

    SONG Yanli; HUA Lin; WANG Ben

    2009-01-01

    The behavior that different magnetic treatment directions induce various amounts of welding residual stress reductions in low alloy steel was studied.Reductions of 26%-28% in the lon-gitudinal stress σ_x were obtained when low frequency alternating magnetic treatment was applied perpendicularly to the welding bead,whereas reductions of 20%-21% in σ_x were measured by using the same treatment parameters except that the field direction was applied parallel to the bead.It is proposed that different extent of stress reductions caused by the above two treatment directions is at-tributed primarily to the alteration of the energy absorbed by domains from the external magnetic field,which part of energy can arouse plastic deformation in microstructures by the motion of domain walls.

  14. Numerical Simulation of Similar and Dissimilar Materials Welding Process; Quantifications of Temperature, Stress, Strain and Deformation

    Directory of Open Access Journals (Sweden)

    Ranjit Shrestha

    2015-02-01

    Full Text Available In the present paper, 3 Dimensional welding simulation was carried out in the FE software ANSYS in order to predict temperature, stress, strain and deformation in the joining of similar and dissimilar materials. The numerical simulation shows that temperature exceeds well above the melting temperature of the substrate material in the welding region. It is found that, higher residual stress is distributed in the weld bead area and surrounding heat affected zone. The stress and strain distribution patterns in the specimen showed that both tended to concentrate at or near points of application of thermal load, and were generally not uniform in these areas. It is also found that Stress and strain were concentrated at corners, edges, and other areas of abrupt change in the shape of the specimen and was also not uniform where the cross-section of the structure changed suddenly, and had large gradients at localized points. The deformation was found maximum at the beginning and the end of welding direction (Y-axis and minimum at the ends of X-axis as they are simply supported in both ends. In addition, among the six different cases of similar and dissimilar materials (S40C+S40C, STS304+STS304, STS316L+STS316L, S40C+STS304, S40C+STS316L, STS304+STS316L, the minimum temperature was found in S40C+STS304 whereas the maximum temperature was S40C+STS316L; the minimum stress was found in case of S40C+STS304 and maximum stress was found in 40C+STS316L; the minimum strain was found in case of S40C+STS304 and maximum strain was found in STS304+STS304; the minimum deformation was found in S40C+S40C and maximum in S40C+STS316L.The prediction show qualitative good agreement with the experimental results found in the literature and hence it was confirmed that the method of finite elements has proved to be successful for proper design analysis.

  15. MEASUREMENT OF NON-UNIFORM RESIDUAL STRESSES BY COMBINED MOIRE INTERFEROMETRY AND HOLE-DRILLING METHOD: THEORY, EXPERIMENTAL METHOD AND APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    亚敏; 戴福隆; 谢惠民; 吕坚

    2003-01-01

    Hole-drilling method is one of the most convenient methods for engineering residual ment data, hole-drilling technique can be used to solve non-uniform residual stress problems, both (MIIHD) for non-uniform residual stress measurement is introduced. Three dimensional finite element model is constructed by ABAQUS to obtain the coefficients for the residual stress calculation.An experimental system including real-time measurement, automatic data processing and residual stresses calculation is established. Two applications for non-uniform in-depth residual stress of surface nanocrystalline material and non-uniform in-plane residual stress of friction stir welding are presented.Experimental results show that MIIHD is effective for both non-uniform in-depth and in-plane residual stress measurements.

  16. Improving Fatigue Performance of AHSS Welds

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [ORNL; Yu, Xinghua [ORNL; ERDMAN III, DONALD L [ORNL; Wang, Yanli [ORNL; Kelly, Steve [ArcelorMittal USA; Hou, Wenkao [ArcelorMittal USA; Yan, Benda [ArcelorMittal USA; Wang, Zhifeng [Colorado School of Mines, Golden; Yu, Zhenzhen [Colorado School of Mines, Golden; Liu, Stephen [Colorado School of Mines, Golden

    2015-03-01

    Reported herein is technical progress on a U.S. Department of Energy CRADA project with industry cost-share aimed at developing the technical basis and demonstrate the viability of innovative in-situ weld residual stresses mitigation technology that can substantially improve the weld fatigue performance and durability of auto-body structures. The developed technology would be costeffective and practical in high-volume vehicle production environment. Enhancing weld fatigue performance would address a critical technology gap that impedes the widespread use of advanced high-strength steels (AHSS) and other lightweight materials for auto body structure light-weighting. This means that the automotive industry can take full advantage of the AHSS in strength, durability and crashworthiness without the concern of the relatively weak weld fatigue performance. The project comprises both technological innovations in weld residual stress mitigation and due-diligence residual stress measurement and fatigue performance evaluation. Two approaches were investigated. The first one was the use of low temperature phase transformation (LTPT) weld filler wire, and the second focused on novel thermo-mechanical stress management technique. Both technical approaches have resulted in considerable improvement in fatigue lives of welded joints made of high-strength steels. Synchrotron diffraction measurement confirmed the reduction of high tensile weld residual stresses by the two weld residual stress mitigation techniques.

  17. The reliability of untempered end plug welds on HT9-clad IFR fuel elements

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, D C; Porter, D L

    1987-02-01

    Welding generally leaves residual stresses in transformed weld zones, which can initiate cracks from flaws already present in the weld zones. When HT9 cools from welding temperatures, a martensite phase forms in the weld fusion zone and heat-affected zone. Because this martensite phase is hard and brittle, it is particularly susceptible to cracking aggravated by residual stresses. This causes concern over the use of untempered welds on HT9-clad fuel elements. To determine if residual stresses present in end-plug weld zones would affect fuel pin performance, HT9 capsules with prototypic TIG- and CD-welded end plugs (in the tempered and as-welded conditions) were pressurized to failure at room temperature, 550{sup 0}C, and 600{sup 0}C. None of the capsules failed in a weld zone. To determine the effects of reactor operating temperatures on untempered welds, prototypic TIG welds were tempered at reactor bulk sodium temperature and an expected sodium outlet temperature for various lengths of time. Subsequent tensile and burst tests of these specimens proved that any embrittling effects that may have been induced in these welds were of no consequence. Hardness tests on longitudinal sections of welds indicated the amount of tempering a weld will receive inreactor after relatively short lengths of time. The pressure burst tests proved that untemperted welds on HT9-clad fuel elements are as reliable as tempered welds; any residual stresses in untempered weld zones were of no consequence. The tempering test showed that welds used in the as-welded condition will sufficiently temper in 7 days at 550{sup 0}C, but will not, sufficiently temper in 7 days at bulk sodium temperature. A comparison of the structure of laser welds to those of CD and TIG welds indicated that untempered laser welds will perform and temper in a manner similar to the TIG welds tested in this effort.

  18. Thermal stress measurement in continuous welded rails using the hole-drilling method

    Science.gov (United States)

    Zhu, Xuan; Lanza di Scalea, Francesco; Fateh, Mahmood

    2016-04-01

    The absence of expansion joints in Continuous Welded Rail (CWR) has created the need for the railroad industry to determine the in-situ level of thermal stresses so as to prevent train accidents caused by rail buckling in hot weather and by rail breakage in cold weather. The development of non-destructive or semi-destructive methods for determining the level of thermal stresses in rails is today a high research priority. This study explores the known hole-drilling method as a possible solution to this problem. A new set of calibration coefficients to compute the relieved stress field with the finer hole depth increments was determined by a 3D Finite Element Analysis that modeled the entire hole geometry, including the mechanics of the hole bottom and walls. To compensate the residual stress components, a linear relationship was experimentally established between the longitudinal and the vertical residual stresses of two common sizes of rails, the 136RE and the 141RE, with statistical significance. This result was then utilized to isolate the longitudinal thermal stress component in hole-drilling tests conducted on the 136RE and 141RE thermally-loaded rails at the Large-scale CWR Test-bed of UCSD's Powell Research Laboratories. The results from the Test-bed showed that the hole-drilling procedure, with the appropriate residual stress compensation, can indeed estimate the in-situ thermal stresses to achieve a +/-5°F accuracy of Neutral Temperature determination with a 90% statistical confidence, which is the desired industry gold standard.

  19. Thermal Stress Analysis of Welded Joint in 1420 Al-Li Alloy Induced by Thermal Cycling

    Institute of Scientific and Technical Information of China (English)

    Hongbin GENG; Song HE; Dezhuang YANG

    2003-01-01

    A model of double grains under plane stress state has been established. According to the double grain model, thermal stress induced by thermal cycling in welding fusion zone is numerically simulated by finite element method, and the microstructures before

  20. Virtual Welded-Joint Design Integrating Advanced Materials and Processing Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Z.; Dong, P.; Liu, S.; Babu, S.; Olson, G.; DebRoy, T.

    2005-04-15

    The primary goal of this project is to increase the fatigue life of a welded-joint by 10 times and to reduce energy use by 25% through product performance and productivity improvements using an integrated modeling approach. The fatigue strength of a welded-joint is currently the bottleneck to design high performance and lightweight welded structures using advanced materials such as high strength steels. In order to achieve high fatigue strength in a welded-joint it is necessary to manage the weld bead shape for lower stress concentration, produce preferable residual stress distribution, and obtain the desired microstructure for improved material toughness and strength. This is a systems challenge that requires the optimization of the welding process, the welding consumable, the base material, as well as the structure design. The concept of virtual welded-joint design has been proposed and established in this project. The goal of virtual welded-joint design is to develop a thorough procedure to predict the relationship of welding process, microstructure, property, residual stress, and the ultimate weld fatigue strength by a systematic modeling approach. The systematic approach combines five sub-models: weld thermal-fluid model, weld microstructure model, weld material property model, weld residual stress model, and weld fatigue model. The systematic approach is thus based on interdisciplinary applied sciences including heat transfer, computational fluid dynamics, materials science, engineering mechanics, and material fracture mechanics. The sub-models are based on existing models with further development. The results from modeling have been validated with critical experiments. The systematic modeling approach has been used to design high fatigue resistant welds considering the combined effects of weld bead geometry, residual stress, microstructure, and material property. In particular, a special welding wire has been developed in this project to introduce

  1. 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....

  2. 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....

  3. Quantifying Residual Stresses by Means of Thermoelastic Stress Analysis

    Science.gov (United States)

    Gyekenyesi, Andrew L.; Baaklini, George Y.

    2001-01-01

    This study focused on the application of the Thermoelastic Stress Analysis (TSA) technique as a tool for assessing the residual stress state of structures. TSA is based on the fact that materials experience small temperature changes when compressed or expanded. When a structure is cyclically loaded, a surface temperature profile results which correlates to the surface stresses. The cyclic surface temperature is measured with an infrared camera. Traditionally, the amplitude of a TSA signal was theoretically defined to be linearly dependent on the cyclic stress amplitude. Recent studies have established that the temperature response is also dependent on the cyclic mean stress (i.e., the static stress state of the structure). In a previous study by the authors, it was shown that mean stresses significantly influenced the TSA results for titanium- and nickel-based alloys. This study continued the effort of accurate direct measurements of the mean stress effect by implementing various experimental modifications. In addition, a more in-depth analysis was conducted which involved analyzing the second harmonic of the temperature response. By obtaining the amplitudes of the first and second harmonics, the stress amplitude and the mean stress at a given point on a structure subjected to a cyclic load can be simultaneously obtained. The experimental results showed good agreement with the theoretical predictions for both the first and second harmonics of the temperature response. As a result, confidence was achieved concerning the ability to simultaneously obtain values for the static stress state as well as the cyclic stress amplitude of structures subjected to cyclic loads using the TSA technique. With continued research, it is now feasible to establish a protocol that would enable the monitoring of residual stresses in structures utilizing TSA.

  4. Estudo das tensões residuais em juntas soldadas de materiais dissimilares e determinação dos limites de resistência à fadiga dos metais de base Study of residual stress in welds of dissimilar material and determination of fatigue strength limits of base metals

    Directory of Open Access Journals (Sweden)

    Tanius Rodrigues Mansur

    2011-09-01

    in design, choice of manufacturing process, choice of consumables and obviously in the preservation and integrity of the equipment. This paper presents results achieved for the residual stresses in dissimilar welds and SNP curves relating tension with the number of cycles and the failure probability for four metals: electrolytic copper, austenitic AISI 304 and AISI 316L stainless steels and A36 carbon steel which were subsequently welded together.

  5. Mechanism of Residual Stress Reduction in Low Alloy Steel by a Low Frequency Alternating Magnetic Treatment

    Institute of Scientific and Technical Information of China (English)

    Yanli Song; Lin Hua

    2012-01-01

    Residual stress reduction in low alloy steel by a low frequency alternating magnetic treatment and its mechanism were investigated. Experimental results revealed that average stress reductions of 20%-24% were obtained in the welded samples. Moreover, compared with the zones with lower initial stress levels, more remarkable stress reductions were obtained in the stress concentration zones. The microstructures and magnetic domains were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Based on the analysis of the microstructure and magnetic domain changes, the mechanism of stress reduction by the magnetic treatment has been concluded: (1) the magneto-plastic deformations mainly due to the more uniform redistribution of dislocations are the fundamental cause of stress relaxation; and (2) surface topography is also proved to affect the magnetic treatment results to some degree by influencing magnetic domains.

  6. 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)

  7. Residual stress distribution in injection molded parts

    Directory of Open Access Journals (Sweden)

    P. Postawa

    2006-08-01

    Full Text Available Purpose: The paper presents the results of the investigations of influence of the amorphous polystyrene (PSprocessing on the diversity of the internal stresses observed in the injection moulded piece.Design/methodology/approach: For the tests, the standardized mould piece designed for the investigations ofthe processing shrinkage of thermoplastics materials has been used. The samples have been prepared using theDesign of Experiment (DoE theory.The state of internal stresses has been analysed by means of photoelastic method (used stress viewer equipmenton the basis of the layout and size of the isochromatics (fields with the same colour, which determine the mouldpiece’s areas where the same value for the difference of main tensions. In the article the results of investigationsof influence of 5 chosen processing parameters such as injection temperature Tw, mould temperature Tf,clamping pressure pd, cooling time tch and the injection speed vw on the changes in isochromatics layout as adeterminant for diversity of internal stresses in injection moulded pieces have been presented.Findings: The performed investigations of the influence of injection conditions on the state of internal stressesreached for injection mould pieces were to determine the parameters of injection at which the achieved state ofthe stresses in the mould piece (described by the difference of main tensions will show the lowest values.Practical implications: Effects of examinations of influence of processing conditions on residual stress ininjection molded parts (presented in the article could find practical application in polymer industry, both smalland large enterprises.Originality/value: New approach to fast estimation of value of residual stresses were present in the paper.

  8. Simulation of three-dimensional stress field in welding process of high-frequency welded pipe%高频焊管在焊接过程中三维应力场的模拟

    Institute of Scientific and Technical Information of China (English)

    何世权; 刘飞; 徐德怀; 钟辉

    2011-01-01

    In the production process of high-frequency welded pipe, the elimination of the high-frequency welding residual stresses caused by high-frequency welding is an important working operation. A knowledge of the residual stress of the welded pipe in advance of welding is significant for the residual stress elimination. Making use of APDL language embedded in ANSYS, a finite element model of high-frequency welded pipe was established. Then the linear thermal source model was used to conduct the computation.Meantime, the thermal boundary conditions and the physical structure of the constraints of this finite element model were also taken into account, so that the three-dimensional stress field and displacement field could be obtained for the high-frequency pipe welding process. From the analysis of result of the finite element simulation, the stress field and displacement field of the welded pipe could be theoretically obtained in advance of the stress relief process.%在高频焊管生产过程中,消除因高频焊接造成的焊管残余应力是一项重要的工序,预先得出焊管残余应力场对于消除焊管残余应力具有指导意义.利用ANSYS参数化语言APDL,建立高频焊管的有限元模型,采用高频焊接线热源模型进行计算,同时考虑高频焊管有限元模型的热边界条件及物理结构约束,从而获得高频焊管在焊接过程中三维应力场及位移场.通过对有限元模拟结果的分析,可以从理论上得出焊管在进行消除残余应力工序前的应力和位移分布.

  9. Residual stresses and vector hysteresis modeling

    Energy Technology Data Exchange (ETDEWEB)

    Ktena, Aphrodite, E-mail: aktena@teiste.gr

    2016-04-01

    Residual stresses in magnetic materials, whether the result of processing or intentional loading, leave their footprint on macroscopic data, such hysteresis loops and differential permeability measurements. A Preisach-type vector model is used to reproduce the phenomenology observed based on assumptions deduced from the data: internal stresses lead to smaller and misaligned grains, hence increased domain wall pinning and angular dispersion of local easy axes, favouring rotation as a magnetization reversal mechanism; misaligned grains contribute to magnetostatic fields opposing the direction of the applied field. The model is using a vector operator which accounts for both reversible and irreversible processes; the Preisach concept for interactions for the role of stress related demagnetizing fields; and a characteristic probability density function which is constructed as a weighed sum of constituent functions: the material is modeled as consisting of various subsystems, e.g. reversal mechanisms or areas subject to strong/weak long range interactions and each subsystem is represented by a constituent probability density function. Our assumptions are validated since the model reproduces the hysteresis loops and differential permeability curves observed experimentally and calculations involving rotating inputs at various residual stress levels are consistent and in agreement with experimental evidence.

  10. Residual stresses and vector hysteresis modeling

    Science.gov (United States)

    Ktena, Aphrodite

    2016-04-01

    Residual stresses in magnetic materials, whether the result of processing or intentional loading, leave their footprint on macroscopic data, such hysteresis loops and differential permeability measurements. A Preisach-type vector model is used to reproduce the phenomenology observed based on assumptions deduced from the data: internal stresses lead to smaller and misaligned grains, hence increased domain wall pinning and angular dispersion of local easy axes, favouring rotation as a magnetization reversal mechanism; misaligned grains contribute to magnetostatic fields opposing the direction of the applied field. The model is using a vector operator which accounts for both reversible and irreversible processes; the Preisach concept for interactions for the role of stress related demagnetizing fields; and a characteristic probability density function which is constructed as a weighed sum of constituent functions: the material is modeled as consisting of various subsystems, e.g. reversal mechanisms or areas subject to strong/weak long range interactions and each subsystem is represented by a constituent probability density function. Our assumptions are validated since the model reproduces the hysteresis loops and differential permeability curves observed experimentally and calculations involving rotating inputs at various residual stress levels are consistent and in agreement with experimental evidence.

  11. Effect of heat input on the microstructure, residual stresses and corrosion resistance of 304L austenitic stainless steel weldments

    Energy Technology Data Exchange (ETDEWEB)

    Unnikrishnan, Rahul, E-mail: rahulunnikrishnannair@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Idury, K.S.N. Satish, E-mail: satishidury@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Ismail, T.P., E-mail: tpisma@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Bhadauria, Alok, E-mail: alokbhadauria1@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Shekhawat, S.K., E-mail: satishshekhawat@gmail.com [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay (IITB), Powai, Mumbai 400076, Maharashtra (India); Khatirkar, Rajesh K., E-mail: rajesh.khatirkar@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Sapate, Sanjay G., E-mail: sgsapate@yahoo.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India)

    2014-07-01

    Austenitic stainless steels are widely used in high performance pressure vessels, nuclear, chemical, process and medical industry due to their very good corrosion resistance and superior mechanical properties. However, austenitic stainless steels are prone to sensitization when subjected to higher temperatures (673 K to 1173 K) during the manufacturing process (e.g. welding) and/or certain applications (e.g. pressure vessels). During sensitization, chromium in the matrix precipitates out as carbides and intermetallic compounds (sigma, chi and Laves phases) decreasing the corrosion resistance and mechanical properties. In the present investigation, 304L austenitic stainless steel was subjected to different heat inputs by shielded metal arc welding process using a standard 308L electrode. The microstructural developments were characterized by using optical microscopy and electron backscattered diffraction, while the residual stresses were measured by X-ray diffraction using the sin{sup 2}ψ method. It was observed that even at the highest heat input, shielded metal arc welding process does not result in significant precipitation of carbides or intermetallic phases. The ferrite content and grain size increased with increase in heat input. The grain size variation in the fusion zone/heat affected zone was not effectively captured by optical microscopy. This study shows that electron backscattered diffraction is necessary to bring out changes in the grain size quantitatively in the fusion zone/heat affected zone as it can consider twin boundaries as a part of grain in the calculation of grain size. The residual stresses were compressive in nature for the lowest heat input, while they were tensile at the highest heat input near the weld bead. The significant feature of the welded region and the base metal was the presence of a very strong texture. The texture in the heat affected zone was almost random. - Highlights: • Effect of heat input on microstructure, residual

  12. Experience with the Notch Stress Approach for Fatigue Assessment of Welded Joints

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Melters; Mouritsen, Ole Ø.; Hansen, Michael Rygaard

    2010-01-01

    In this paper, fatigue assessment using the notch stress approach is discussed based on re-analysis of many fatigue test results and experience from practical application. Three topics are treated; evaluation of the fatigue strength for as-welded details (FAT225) in the notch stress system......, problems regarding assessment of mild-SCF details and a novel proposal for extension of the notch stress approach for use with post-weld treated details....

  13. Fundamentals of evaluation and diagnostics of welded structures

    CERN Document Server

    Nedoseka, Anatoliy Yakovlevich

    2012-01-01

    Provides an essential guide to the key principles and problems involved in the analysis of welded structures. This title discusses design issues, key equations and calculations, and the effects of varied heat sources in relation to the temperature field in welding. It goes on to explore welding stresses and strains.$bFundamentals of evaluation and diagnostics of welded structures provides an essential guide to the key principles and problems involved in the analysis of welded structures. Chapter one discusses design issues, key equations and calculations, and the effects of varied heat sources in relation to the temperature field in welding. Chapter two goes on to explore welding stresses and strains. Fracture mechanics and the load-carrying capacity of welded structures are the focus of chapter three. Chapter four considers diagnostics and prediction of the residual life of welded structures, whilst acoustic emission techniques for the analysis of welded structures are reviewed in Chapter five. Finally, chap...

  14. Residual stress around the cortical surface in bovine femoral diaphysis.

    Science.gov (United States)

    Yamada, Satoshi; Tadano, Shigeru

    2010-04-01

    Residual stress in living tissue plays an important role in mechanical strength. We have reported that residual stress exists in the bone tissue of a rabbit's tibiofibula. The purpose of this study is to measure the residual stress around the outer cortical region of bovine femoral diaphysis and to discuss the distribution of the stress. This work proposed the sin(2) psi method of X-ray diffraction to the measurement of residual stresses in bone tissue. In this method, residual stress can be estimated from the variation in the interplanar spacings orientated to a number of directions without the lattice strain in the stress direction. Four-point bending tests of strip specimens taken from bovine femoral diaphysis were carried out during X-ray irradiation in advance. In the proximal, middle, and distal sections of bovine femoral diaphyses, the residual stresses at the cortical surface were measured using characteristic Mo-Kalpha X-rays. The bending tests of strip specimens with X-ray irradiation showed that the method could reliably estimate residual stresses in the bone tissue. The residual stress of the bone axial direction was larger than that of the circumferential direction. The stresses in the middle part of five diaphyses along the bone axial direction were tensile. The maximum stress was 162 MPa at the lateral position and the minimum was 78 MPa at the posterior position. The residual stress in the bone axial direction varies around the circumferential region. In addition, the bone axial distributions of residual stresses were different in the proximal, middle, and distal sections of the individual femur. Furthermore, it was confirmed that residual stress in the bone tissue was released by the cutting out of the specimen. The residual stresses in bone tissue could be measured by this method. The results show that residual stress in the bone axial direction at the cortical surface in bovine femoral diaphysis is tensile and varies around the circumferential

  15. Impact of the Weld Geometry on the Stress Intensity Factor of the Welded T-Joint Exposed to the Tensile Force and the Bending Moment

    Science.gov (United States)

    Djoković, Jelena M.; Nikolić, Ružica R.; Bujňák, Ján

    2015-12-01

    In this paper it is analyzed the welded T-joint exposed to the axial tensile force and the bending moment, for determining the impact of the weld geometry on the fracture mechanics parameters. The stress intensity factor was calculated analytically, based on the concept of the linear elastic fracture mechanics (LEFM), by application of the Mathematica® programming routine. The presence of the weld was taken into account through the corresponding correction factors. The results show that increase of the size of the triangular welds leads to decrease of the stress intensity factor, while the SIF increases with increase of the welds' width. The ratio of the two welded plates' thicknesses shows that plate thicknesses do not exhibit significant influence on the stress intensity factor behavior.

  16. 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

    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...... 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....

  17. Measurements of residual stress in fracture mechanics coupons

    Energy Technology Data Exchange (ETDEWEB)

    Prime, Michael B [Los Alamos National Laboratory; Hill, Michael R [U.C. DAVIS; Nav Dalen, John E [HILL ENGINEERING

    2010-01-01

    This paper describes measurements of residual stress in coupons used for fracture mechanics testing. The primary objective of the measurements is to quantify the distribution of residual stress acting to open (and/or close) the crack across the crack plane. The slitting method and the contour method are two destructive residual stress measurement methods particularly capable of addressing that objective, and these were applied to measure residual stress in a set of identically prepared compact tension (C(T)) coupons. Comparison of the results of the two measurement methods provides some useful observations. Results from fracture mechanics tests of residual stress bearing coupons and fracture analysis, based on linear superposition of applied and residual stresses, show consistent behavior of coupons having various levels of residual stress.

  18. Residual Stresses Modeled in Thermal Barrier Coatings

    Science.gov (United States)

    Freborg, A. M.; Ferguson, B. L.; Petrus, G. J.; Brindley, W. J.

    1998-01-01

    Thermal barrier coating (TBC) applications continue to increase as the need for greater engine efficiency in aircraft and land-based gas turbines increases. However, durability and reliability issues limit the benefits that can be derived from TBC's. A thorough understanding of the mechanisms that cause TBC failure is a key to increasing, as well as predicting, TBC durability. Oxidation of the bond coat has been repeatedly identified as one of the major factors affecting the durability of the ceramic top coat during service. However, the mechanisms by which oxidation facilitates TBC failure are poorly understood and require further characterization. In addition, researchers have suspected that other bond coat and top coat factors might influence TBC thermal fatigue life, both separately and through interactions with the mechanism of oxidation. These other factors include the bond coat coefficient of thermal expansion, the bond coat roughness, and the creep behavior of both the ceramic and bond coat layers. Although it is difficult to design an experiment to examine these factors unambiguously, it is possible to design a computer modeling "experiment" to examine the action and interaction of these factors, as well as to determine failure drivers for TBC's. Previous computer models have examined some of these factors separately to determine their effect on coating residual stresses, but none have examined all the factors concurrently. The purpose of this research, which was performed at DCT, Inc., in contract with the NASA Lewis Research Center, was to develop an inclusive finite element model to characterize the effects of oxidation on the residual stresses within the TBC system during thermal cycling as well as to examine the interaction of oxidation with the other factors affecting TBC life. The plasma sprayed, two-layer thermal barrier coating that was modeled incorporated a superalloy substrate, a NiCrAlY bond coat, and a ZrO2-8 wt % Y2O3 ceramic top coat. We

  19. Residual stress in bone structure and tissue of rabbit's tibiofibula.

    Science.gov (United States)

    Tadano, Shigeru; Okoshi, Taro

    2006-01-01

    This paper presents an X-ray diffraction method of measuring the residual stress/strain in bone tissue of rabbit's tibia. To derive the residual stress, bone powder of the diameter less than 40 micrometers was used as a control specimen at non-stressed state. From the X-ray measurements, it was clear that the distribution of residual stress existed in the bone tissue. The tensile residual stress at bone axial direction occurred in the proximal-medial region of rabbit's tibia. The compressive stress occurred in the other regions. In addition, the mechanism to generate the residual stress was investigated by sequential cutting of the tibiofibula system from bone structure scale to bone tissue scale. The remodeling is a phenomenon that the bone structure adapts functionally to mechanical environment. The residual stress will become a mechanical trigger to induce the remodeling.

  20. Numerical simulation on temperature and stress fields of CLAM steel TIG weld%CLAM钢TIG焊接头温度场和应力场数值模拟

    Institute of Scientific and Technical Information of China (English)

    雷玉成; 朱强; 尹莎; 巨新

    2011-01-01

    ANSYS thermal-structural coupling technology, Parametric Design Language, life-death element technique, and double ellipsoid heat source were applied togegher in the numerical simulation of temperature and stress fields on single layer welding and the single-sided double layer welding of CLAM steel TIG weld joints. Without considering phase change and only considering the effects of residual stress field, the stress field based on temperature field data was calculated. The results of simulation with that of experiment were compared. The numerical results of residual stress distribution are almost consistent with the experimental ones. On middle section of the surface, longitudinal stress is tensile stress near the weld zone, reaches the maximum in the fusion area, and turn to compressive stress away from weld zone.The transverse stress is small tensile stress. Residual stress of single-sided double-layer welding specimen is lower than that of single layer welding specimen.%运用ANSYS的热-结构耦合技术,采用APDL参数化语言及生死单元技术,以双椭球热源作为内热源,对CLAM钢TIG焊对接单层焊和单面双层焊的温度场进行了数值模拟.在不考虑焊接温度场对材料相变影响,而仅考虑对残余应力场影响的条件下,以温度场的计算数据为依据进行应力场的计算,并将应力场的模拟结果与试验结果进行比较.分析结果表明:焊件残余应力的实测值和模拟结果中残余应力分布比较吻合;在焊件截面上表面,纵向残余应力在近缝区为拉应力,且在熔合区附近达到最大,而远离焊缝处转变为压应力;横向残余应力比较小,且均为拉应力;单面双层焊件表面残余应力比单层焊件的残余应力小.

  1. Minimization and Mitigation of Wire EDM Cutting Errors in the Application of the Contour Method of Residual Stress Measurement

    Science.gov (United States)

    Ahmad, Bilal; Fitzpatrick, Michael E.

    2016-01-01

    The contour method of residual stress measurement relies on the careful application of wire electro-discharge machining (WEDM) for the cutting stage. Changes in material removal rates during the cut lead to errors in the final calculated values of residual stress. In this study, WEDM cutting parameters have been explored to identify the optimum conditions for contour method residual stress measurements. The influence of machine parameters on the surface roughness and cutting artifacts in the contour cut is discussed. It has been identified that the critical parameter in improving the surface finish is the spark pulse duration. A typical cutting artifact and its impact on measured stress values have been identified and demonstrated for a contour cut in a welded marine steel. A procedure is presented to correct contour displacement data from the influence of WEDM cutting artifacts, and is demonstrated on the correction of a measured weld residual stress. The corrected contour method improved the residual stress magnitude up to 150 MPa. The corrected contour method results were validated by X-ray diffraction, incremental center hole drilling, and neutron diffraction.

  2. Welding Curriculum.

    Science.gov (United States)

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This competency-based curriculum guide is a handbook for the development of welding trade programs. Based on a survey of Alaskan welding employers, it includes all competencies a student should acquire in such a welding program. The handbook stresses the importance of understanding the principles associated with the various elements of welding.…

  3. Re-analysis of fatigue data for welded joints using the notch stress approach

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Melters; Mouritsen, Ole Ø.; Hansen, Michael Rygaard

    2010-01-01

    Experimental fatigue data for welded joints have been collected and subjected to re-analysis using the notch stress approach according to IIW recommendations. This leads to an overview regarding the reliability of the approach, based on a large number of results (767 specimens). Evidently......-welded joints agree quite well with the FAT 225 curve; however a reduction to FAT 200 is suggested in order to achieve approximately the same safety as observed in the nominal stress approach....

  4. Nondestructive testing and characterization of residual stress field using an ultrasonic method

    Science.gov (United States)

    Song, Wentao; Xu, Chunguang; Pan, Qinxue; Song, Jianfeng

    2016-03-01

    To address the difficulty in testing and calibrating the stress gradient in the depth direction of mechanical components, a new technology of nondestructive testing and characterization of the residual stress gradient field by ultrasonic method is proposed based on acoustoelasticity theory. By carrying out theoretical analysis, the sensitivity coefficients of different types of ultrasonic are obtained by taking the low carbon steel(12%C) as a research object. By fixing the interval distance between sending and receiving transducers, the mathematical expressions of the change of stress and the variation of time are established. To design one sending-one receiving and oblique incidence ultrasonic detection probes, according to Snell law, the critically refracted longitudinal wave (LCR wave) is excited at a certain depth of the fixed distance of the tested components. Then, the relationship between the depth of LCR wave detection and the center frequency of the probe in Q235 steel is obtained through experimental study. To detect the stress gradient in the depth direction, a stress gradient LCR wave detection model is established, through which the stress gradient formula is derived by the relationship between center frequency and detecting depth. A C-shaped stress specimen of Q235 steel is designed to conduct stress loading tests, and the stress is measured with the five group probes at different center frequencies. The accuracy of ultrasonic testing is verified by X-ray stress analyzer. The stress value of each specific depth is calculated using the stress gradient formula. Accordingly, the ultrasonic characterization of residual stress field is realized. Characterization results show that the stress gradient distribution is consistent with the simulation in ANSYS. The new technology can be widely applied in the detection of the residual stress gradient field caused by mechanical processing, such as welding and shot peening.

  5. Nondestructive Testing and Characterization of Residual Stress Field Using an Ultrasonic Method

    Institute of Scientific and Technical Information of China (English)

    SONG Wentao; XU Chunguang; PAN Qinxue; SONG Jianfeng

    2016-01-01

    To address the difficulty in testing and calibrating the stress gradient in the depth direction of mechanical components, a new technology of nondestructive testing and characterization of the residual stress gradient field by ultrasonic method is proposed based on acoustoelasticity theory. By carrying out theoretical analysis, the sensitivity coefficients of different types of ultrasonic are obtained by taking the low carbon steel(12%C) as a research object. By fixing the interval distance between sending and receiving transducers, the mathematical expressions of the change of stress and the variation of time are established. To design one sending-one receiving and oblique incidence ultrasonic detection probes, according to Snell law, the critically refracted longitudinal wave (LCR wave) is excited at a certain depth of the fixed distance of the tested components. Then, the relationship between the depth of LCR wave detection and the center frequency of the probe in Q235 steel is obtained through experimental study. To detect the stress gradient in the depth direction, a stress gradient LCR wave detection model is established, through which the stress gradient formula is derived by the relationship between center frequency and detecting depth. A C-shaped stress specimen of Q235 steel is designedto conduct stress loading tests, and the stress is measured with the five group probes at different center frequencies. The accuracy of ultrasonic testing is verified by X-ray stress analyzer. The stress value of each specific depth is calculated using the stress gradient formula. Accordingly, the ultrasonic characterization of residual stress field is realized. Characterization results show that the stress gradient distribution is consistent with the simulation in ANSYS. The new technology can be widely applied in the detection of the residual stress gradient field caused by mechanical processing, such as welding and shot peening.

  6. Stress-strain state and durability of mechanically inhomogeneous welds under low-cycle loading

    Science.gov (United States)

    Brazenas, A.; Daunis, M.

    2008-02-01

    Relations are proposed for the determination of the stress-strain state, strength, and life of butt welds with mild and hard interlayers under cyclic elastoplastic tension-compression. The accumulation of cyclic and quasistatic damages is determined with allowance for the redistribution of the cyclic elastoplastic strains and hardness of the stress state due to changes in the cyclic properties of separate regions of welds. The theoretical distribution of cyclic strains and the durability of welds under cyclic elastoplastic loading are supported by experimental data

  7. Accelerated crack growth, residual stress, and a cracked zinc coated pressure shell

    Science.gov (United States)

    Dittman, Daniel L.; Hampton, Roy W.; Nelson, Howard G.

    1987-01-01

    During a partial inspection of a 42 year old, operating, pressurized wind tunnel at NASA-Ames Research Center, a surface connected defect 114 in. long having an indicated depth of a 0.7 in. was detected. The pressure shell, constructed of a medium carbon steel, contains approximately 10 miles of welds and is cooled by flowing water over its zinc coated external surface. Metallurgical and fractographic analysis showed that the actual detect was 1.7 in. deep, and originated from an area of lack of weld penetration. Crack growth studies were performed on the shell material in the laboratory under various loading rates, hold times, and R-ratios with a simulated shell environment. The combination of zinc, water with electrolyte, and steel formed an electrolytic cell which resulted in an increase in cyclic crack growth rate by as much as 500 times over that observed in air. It was concluded that slow crack growth occurred in the pressure shell by a combination of stress corrosion cracking due to the welding residual stress and corrosion fatigue due to the cyclic operating stress.

  8. Accelerated crack growth, residual stress, and a cracked zinc coated pressure shell

    Science.gov (United States)

    Dittman, Daniel L.; Hampton, Roy W.; Nelson, Howard G.

    1987-01-01

    During a partial inspection of a 42 year old, operating, pressurized wind tunnel at NASA-Ames Research Center, a surface connected defect 114 in. long having an indicated depth of a 0.7 in. was detected. The pressure shell, constructed of a medium carbon steel, contains approximately 10 miles of welds and is cooled by flowing water over its zinc coated external surface. Metallurgical and fractographic analysis showed that the actual detect was 1.7 in. deep, and originated from an area of lack of weld penetration. Crack growth studies were performed on the shell material in the laboratory under various loading rates, hold times, and R-ratios with a simulated shell environment. The combination of zinc, water with electrolyte, and steel formed an electrolytic cell which resulted in an increase in cyclic crack growth rate by as much as 500 times over that observed in air. It was concluded that slow crack growth occurred in the pressure shell by a combination of stress corrosion cracking due to the welding residual stress and corrosion fatigue due to the cyclic operating stress.

  9. Stress corrosion crack initiation of alloy 182 weld metal in primary coolant - Influence of chemical composition

    Energy Technology Data Exchange (ETDEWEB)

    Calonne, O.; Foucault, M.; Steltzlen, F. [AREVA (France); Amzallag, C. [EDF SEPTEN (France)

    2011-07-01

    Nickel-base alloys 182 and 82 have been used extensively for dissimilar metal welds. Typical applications are the J-groove welds of alloy 600 vessel head penetrations, pressurizer penetrations, heater sleeves and bottom mounted instrumented nozzles as well as some safe end butt welds. While the overall performance of these weld metals has been good, during the last decade, an increasing number of cases of stress corrosion cracking of Alloy 182 weld metal have been reported in PWRs. In this context, the role of weld defects has to be examined. Their contribution in the crack initiation mechanism requires laboratory investigations with small scale characterizations. In this study, the influence of both alloy composition and weld defects on PWSCC (Stress Corrosion Cracking in Primary Water) initiation was investigated using U-bend specimens in simulated primary water at 320 C. The main results are the following: -) the chemical compositions of the weld deposits leading to a large propensity to hot cracking are not the most susceptible to PWSCC initiation, -) macroscopically, superficial defects did not evolve during successive exposures. They can be included in large corrosion cracks but their role as 'precursors' is not yet established. (authors)

  10. Damage Tolerance Assessment of Friction Pull Plug Welds

    Science.gov (United States)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process developed and patented by The Welding Institute in Cambridge, England. Friction stir welding has been implemented in the aerospace industry in the fabrication of longitudinal welds in pressurized cryogenic propellant tanks. As the industry looks to implement friction stir welding in circumferential welds in pressurized cryogenic propellant tanks, techniques to close out the termination hole associated with retracting the pin tool are being evaluated. Friction pull plug welding is under development as a one means of closing out the termination hole. A friction pull plug weld placed in a friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite, plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size in the test or service environments. Test data relating residual strength capability to flaw size in two aluminum alloy friction plug weld configurations is presented.

  11. Study on cracking of welding overlay based on the theory of diffusion-induced stress

    Institute of Scientific and Technical Information of China (English)

    Xiliang ZHANG; Changyu ZHOU

    2011-01-01

    Hydrogen diffusion in the wall of hydrogenation reactor for three situations,i.e. operating,normal shutdown and abnormal shutdown,was numerically simulated based on the finite element program-ABAQUS. The formula of diffusion-induced stress was deduced for model of the thin walled cylinder. Distribution of diffusion-induced stress in the wall of hydrogenation reactor was studied. The results showed that the maximum stress was at the fusion surface between welding overlay and base metal,and which would increase with cooling rate. The crack will initiate and propagate from fusion surface to welding overlay when the diffusion-induced stress is higher than yield stress,but it will not propagate to the base metal. Diffusion-induced stress is one of the important factors for crack initiation and propagation of welding overlay of hydrogenation reactor.

  12. Residual stress in quenched 7075 aluminum alloy thick plates

    Institute of Scientific and Technical Information of China (English)

    林高用; 张辉; 朱伟; 彭大暑; 梁轩; 周鸿章

    2003-01-01

    The influence of quenching water temperature, pre-stretching amount and aging temperature and times on residual stress in 7075 aluminum thick plate was studied by the measurement of residual stress using drilling hole method. The results indicate that residual stress decreases by 30% with increasing quenching water temperature from 40 ℃ to 80 ℃, 20% with increasing aging temperature from 100 ℃ to 180 ℃,and 20% with increasing aging times from 5 h to 25 h. Also, residual stress decreases to zero with increasing pre-stretching amount to approximately 2%. Hence, residual stress in 7075 aluminum thick plate is reduced by the control of quenching water temperature at 80 ℃ and with pre-stretching amount of about 2%. An optimal aging temperature and time should be systemically investigated to obtain combination of high mechanical performances and lower residual stress for manufacturing of 7075 aluminum alloy thick plates.

  13. Residual Stress Determination from a Laser-Based Curvature Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Swank, William David; Gavalya, Rick Allen; Wright, Julie Knibloe; Wright, Richard Neil

    2000-05-01

    Thermally sprayed coating characteristics and mechanical properties are in part a result of the residual stress developed during the fabrication process. The total stress state in a coating/substrate is comprised of the quench stress and the coefficient of thermal expansion (CTE) mismatch stress. The quench stress is developed when molten particles impact the substrate and rapidly cool and solidify. The CTE mismatch stress results from a large difference in the thermal expansion coefficients of the coating and substrate material. It comes into effect when the substrate/coating combination cools from the equilibrated deposit temperature to room temperature. This paper describes a laser-based technique for measuring the curvature of a coated substrate and the analysis required to determine residual stress from curvature measurements. Quench stresses were determined by heating the specimen back to the deposit temperature thus removing the CTE mismatch stress. By subtracting the quench stress from the total residual stress at room temperature, the CTE mismatch stress was estimated. Residual stress measurements for thick (>1mm) spinel coatings with a Ni-Al bond coat on 304 stainless steel substrates were made. It was determined that a significant portion of the residual stress results from the quenching stress of the bond coat and that the spinel coating produces a larger CTE mismatch stress than quench stress.

  14. Residual stress profiling of an aluminum alloy by laser ultrasonics

    Institute of Scientific and Technical Information of China (English)

    PAN Yondong; QIAN Menglu; XU Weijiang; M. OURAK

    2004-01-01

    A residual-stress profile along the thickness of an aluminum alloy sheet is determined by laser-ultrasonic technique. Surface acoustic waves are generated by a Nd:YAG pulse laser and detected by a Heterodyne interferometer on a lateral free surface of the sheet. The distribution of residual stress is determined by measuring the relative variation of the wavevelocities at different location of the sample along its thickness. This technique is validated by three different residual stress profiles obtained experimentally.

  15. Impact of the Weld Geometry on the Stress Intensity Factor of the Welded T-Joint Exposed to the Tensile Force and the Bending Moment

    Directory of Open Access Journals (Sweden)

    Djoković Jelena M.

    2015-12-01

    Full Text Available In this paper it is analyzed the welded T-joint exposed to the axial tensile force and the bending moment, for determining the impact of the weld geometry on the fracture mechanics parameters. The stress intensity factor was calculated analytically, based on the concept of the linear elastic fracture mechanics (LEFM, by application of the Mathematica® programming routine. The presence of the weld was taken into account through the corresponding correction factors. The results show that increase of the size of the triangular welds leads to decrease of the stress intensity factor, while the SIF increases with increase of the welds’ width. The ratio of the two welded plates’ thicknesses shows that plate thicknesses do not exhibit significant influence on the stress intensity factor behavior.

  16. Modelling and Analysis of Phase Transformations and Stresses in Laser Welding Process / Modelowanie I Analiza Przemian Fazowych I Naprężeń W Procesie Spawania Laserowego

    Directory of Open Access Journals (Sweden)

    Piekarska W.

    2015-12-01

    Full Text Available The work concerns the numerical modelling of structural composition and stress state in steel elements welded by a laser beam. The temperature field in butt welded joint is obtained from the solution of heat transfer equation with convective term. The heat source model is developed. Latent heat of solid-liquid and liquid-gas transformations as well as latent heats of phase transformations in solid state are taken into account in the algorithm of thermal phenomena. The kinetics of phase transformations in the solid state and volume fractions of formed structures are determined using classical formulas as well as Continuous-Heating-Transformation (CHT diagram and Continuous-Cooling-Transformation (CCT diagram during welding. Models of phase transformations take into account the influence of thermal cycle parameters on the kinetics of phase transformations during welding. Temporary and residual stress is obtained on the basis of the solution of mechanical equilibrium equations in a rate form. Plastic strain is determined using non-isothermal plastic flow with isotropic reinforcement, obeying Huber-Misses plasticity condition. In addition to thermal and plastic strains, the model takes into account structural strain and transformation plasticity. Changing with temperature and structural composition thermophysical parameters are included into constitutive relations. Results of the prediction of structural composition and stress state in laser butt weld joint are presented.

  17. Investigation on the effects of geometric variables on the residual stresses and PWSCC growth in the RPV BMI penetration nozzles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Sung; Ra, Myoung Soo [Sunchon National University, Suncheon (Korea, Republic of); Lee, Kyoung Soo [Korea Hydro Nuclear Company, Daejeon (Korea, Republic of)

    2015-03-15

    This study investigated the effects of various geometric variables on the residual stresses and PWSCC growth of RPV BMI penetration nozzles. An FE residual stress analysis procedure was developed and validated from the viewpoint of FFS assessment. The validated FE residual stress analysis procedure and the PWSCC growth assessment procedure in the ASME B and PV Code, Sec.XI were applied to the BMI penetration nozzles with specified ranges of the geometric variables. The total stresses at steady state during normal operation including welding residual stresses increase with increasing inclination angle of the BMI nozzles, and with tilt angle, depth, and root width of the J-groove weld. The lifetime from the assumed initial crack to the acceptance criteria according to the ASME B and PV Code, Sec.XI also decreases under these conditions. The total stresses decrease and the lifetime increases with increasing nozzle thickness, but outer radius of the BMI nozzles has an insignificant effect on both of these factors.

  18. 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.

  19. Blocks and residual stresses in shaped sapphire single crystals

    Science.gov (United States)

    Krymov, V. M.; Nosov, Yu. G.; Bakholdin, S. I.; Maslov, V. N.; Shul‧pina, I. L.; Nikolaev, V. I.

    2017-01-01

    The formation of blocks and residual stresses in shaped sapphire crystals grown from the melt by the Stepanov method (EFG) has been studied. The probability of block formation is higher for the growth along the c axis compared to that grown in the a-axis direction. The distribution of residual stress in sapphire crystals of tubular, rectangular and round cross section was measured by the conoscopy method. It was found that the magnitude of the residual stress increases from the center to the periphery of the crystal and reaches up to about 20 MPa. Residual stress tensor components for solid round rod and tubular single crystals were determined by numerical integration.

  20. Tensiones residuales en uniones soldadas por FSW en aluminio 7075-T651 Residual stresses in 7075-T651 FSW joint

    Directory of Open Access Journals (Sweden)

    Leonardo N. Tufaro

    2012-12-01

    the structural integrity of a component in service and usually have a major influence on their fatigue life, among other failure mechanisms. In recent years Friction-Stir Welding (FSW has revolutionized the welding technology. Its main application has been given in aluminum alloys, but nowadays can be applicable to different materials. One of the several advantages of this process is a lower level of residual stresses, because the thermal gradients introduced during welding are lower. Among aluminum alloys used for structural applications, 7XXX strain-aged series are usually employed in the aerospace industry, because of their high strength. The aim of this paper is to analyze the effect of welding speed of FSW on residual stresses in aluminum AA7075-T651 joints, using sectioning technique. Coupons were welded AA7075-T651 FSW of 150x150x4 mm by varying the welding speed between 51 and 206 mm.min-1. During the welding thermal cycles were acquired. Subsequently, longitudinal residual stresses measured at different distances from the weld, in each case. Based on the acquired thermal cycling thermal gradients were obtained in the measurement area. Maximum residual stresses ranged from 52 to 78 MPa, corresponding to a range of 10 and 15% of the yield strength. They increased with increasing welding speed, consistent with an increase in the thermal gradient observed. These residual stresses values are lower than those obtained for the welding of these materials by type GMAW processes.

  1. Welding.

    Science.gov (United States)

    Cowan, Earl; And Others

    The curriculum guide for welding instruction contains 16 units presented in six sections. Each unit is divided into the following areas, each of which is color coded: terminal objectives, specific objectives, suggested activities, and instructional materials; information sheet; transparency masters; assignment sheet; test; and test answers. The…

  2. 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.

  3. Analysis of overlay weld effect on preventing PWSCC in dissimilar metal weld

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Gun; Oh, Chang Kyun; Jin, Tae Eun [Korea Power Engineering Co., Inc., Yongin (Korea, Republic of); Kim, Yong Tae [Korea Plant Service and Engineering Co., Ltd., Seongnam (Korea, Republic of); Yoo, Sung Soo [Korea Hydro and Nuclear Power Co., Ltd., Seoul (Korea, Republic of)

    2009-07-01

    PWSCC(Primary Stress Corrosion Cracking) in Alloy 82/182 butt welds is the problem affecting safety and integrity of nuclear power plant. PWSCC can be occurred in high magnitude of tensile residual stress, such as Alloy 82/182 dissimilar metal welds in Pressurizer(PZR) nozzles. There have been related incidents recently at the dissimilar metal welds in overseas nuclear power plants. Overlay weld is the one of the effective methods to decrease tensile residual stress of inside surface, which will result in preventing PWSCC. In this paper, overlay weld conditions on the purpose of preventing PWSCC was explained and the benefit of the overlay weld was confirmed performing finite element analysis.

  4. Analysis of Overlay Weld Effect on Preventing PWSCC in Dissimilar Metal Weld

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Gun; Oh, Chang Kyun; Park, Heung Bae; Jin, Tae Eun [Korea Power Engineering Company, Daejeon (Korea, Republic of)

    2010-01-15

    PWSCC(Primary Stress Corrosion Cracking) in Alloy 82/182 butt welds is the problem affecting safety and integrity of nuclear power plant. PWSCC can be occurred in the area that is at high magnitude of tensile residual stress, such as Alloy 82/182 dissimilar metal welds in PZR(pressurizer) nozzles. There have been a number of incidents recently at the dissimilar metal welds in overseas nuclear power plants. Overlay weld is the one of the effective methods to decrease tensile residual stress of inside surface, which will result in preventing PWSCC. In this paper, overlay weld conditions on the purpose of preventing PWSCC was explained and the benefit of the overlay weld was confirmed performing finite element analysis.

  5. Residual stresses and durability in cold drawn eutectoid steel wires

    Science.gov (United States)

    Atienza, J. M.; Elices, M.; Ruiz-Hervias, J.; Caballero, L.; Valiente, A.

    2007-04-01

    Prestressing steel wires have excellent mechanical properties but there is a need to improve their durability in aggressive environments. In this work, the influence of residual stresses on the environmentally assisted cracking of these wires is studied. A good correlation has been found between residual stresses at the surface of the wires and the time to rupture during stress corrosion test proposed by the International Federation of Prestressing. Wires with the same microstructure, surface quality and mechanical properties show very different behaviour in aggressive environments depending on their residual stress state. Research shows that environmentally assisted cracking can be improved significantly by acting on the surface residual stresses produced by wire drawing. In addition, in this study a post-drawing treatment to generate compressive residual stresses at the surface of the wires is proposed.

  6. Computer modeling of the stress-strain state of a linear friction welded disk

    Directory of Open Access Journals (Sweden)

    V. Bychkov

    2015-09-01

    Full Text Available The paper is dedicated to design issues of tooling for linear friction welding (LFW machine. Computer model of a LFW machine was built. As a result of computer simulation, the stress-strain state of the machine and disk module for linear friction welding of aluminum alloy blisks also was obtained. On the basis of the results of computer simulation a module with a replaceable unit and a new variant fixing of disc in the module were designed.

  7. Validations of Computational Weld Models: Comparison of Residual Stresses

    Science.gov (United States)

    2010-08-01

    valider la capacité du modèle informatique de calculer les contraintes résiduelles dans des structures réparées par ce type de soudage de rechargement...modèle informatique . Les mesures de la dureté de la plaque laissent supposer que cette propriété varie grandement dans l’espace, c.-à-d. qu’elle est

  8. 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.

  9. 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.

  10. Thermal Residual Stress in Environmental Barrier Coated Silicon Nitride - Modeled

    Science.gov (United States)

    Ali, Abdul-Aziz; Bhatt, Ramakrishna T.

    2009-01-01

    When exposed to combustion environments containing moisture both un-reinforced and fiber reinforced silicon based ceramic materials tend to undergo surface recession. To avoid surface recession environmental barrier coating systems are required. However, due to differences in the elastic and thermal properties of the substrate and the environmental barrier coating, thermal residual stresses can be generated in the coated substrate. Depending on their magnitude and nature thermal residual stresses can have significant influence on the strength and fracture behavior of coated substrates. To determine the maximum residual stresses developed during deposition of the coatings, a finite element model (FEM) was developed. Using this model, the thermal residual stresses were predicted in silicon nitride substrates coated with three environmental coating systems namely barium strontium aluminum silicate (BSAS), rare earth mono silicate (REMS) and earth mono di-silicate (REDS). A parametric study was also conducted to determine the influence of coating layer thickness and material parameters on thermal residual stress. Results indicate that z-direction stresses in all three systems are small and negligible, but maximum in-plane stresses can be significant depending on the composition of the constituent layer and the distance from the substrate. The BSAS and REDS systems show much lower thermal residual stresses than REMS system. Parametric analysis indicates that in each system, the thermal residual stresses can be decreased with decreasing the modulus and thickness of the coating.

  11. Residual stress measurement in silicon sheet by shadow moire interferometry

    Science.gov (United States)

    Kwon, Y.; Danyluk, S.; Bucciarelli, L.; Kalejs, J. P.

    1987-01-01

    A shadow moire interferometry technique has been developed to measure residual strain in thin silicon sheet. The curvature of a segment of sheet undergoing four-point bending is analyzed to include the applied bending moments, the in-plane residual stresses, and the 'end effect' of the sheet since it is of finite length. The technique is applied to obtain residual stress distributions for silicon sheet grown by the edge-defined film-fed growth technique.

  12. Study and practice of decreasing residual stress with residual heat of casting

    Institute of Scientific and Technical Information of China (English)

    Tong Siyi; Liu Lin

    2008-01-01

    A new technique for reducing the residual stress within a casting by using of the residual heat in the casting is presented. The new technique has been applied by Guangxi Yuchai Machinery Company Limited and the result shows remarkably applicable. The casting's residual stress can be reduced to less than 60 MPa while the saving in energy can be about 101.1 kW·h per ton of castings, as compared with traditional technique.

  13. Effects of distance between arc and heat sink on stress and distortion in DC-LSND welding technology

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The characteristics of temperatures, stresses and strains fields have been studied numerically for a titanium alloy sheet welded with an improved gas tungsten arc welding method, in which a trailing spot heat sink is introduced to control the welding stress and distortion. The impinging jet model is employed to describe the intense heat transfer between the cooling media and the top surface of the workpiece. The influence of the distance between arc and heat sink is investigated. Results show that there is an ideal range of distance. Using the ideal distance, a low stress and no distortion welding structure can be derived.

  14. Multiaxial fatigue assessment of welded joints using the notch stress approach

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Melters

    2016-01-01

    This paper presents an evaluation of the safety involved when performing fatigue assessment of multiaxially loaded welded joints. The notch stress approach according to the IIW is used together with 8 different multiaxial criteria, including equivalent stress-, interaction equation- and critical...

  15. Characterization of residual stresses generated during inhomogeneous plastic deformation

    DEFF Research Database (Denmark)

    Lorentzen, T.; Faurholdt, T.; Clausen, B.;

    1998-01-01

    Residual stresses generated by macroscopic inhomogeneous plastic deformation are predicted by an explicit finite element (FE) technique. The numerical predictions are evaluated by characterizing the residual elastic strains by neutron diffraction using two different (hkl) reflections. Intergranular...... residual elastic strains between subsets of grains are predicted numerically and verified by neutron diffraction. Subsequently, the measured residual strain profiles in the test samples are modified by the intergranular strains and compared to the engineering predictions of the FE technique. Results...

  16. 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......: the far-field stress, plate thickness, hole diameter and the interaction between holes and edges and corners. The work presents novel results for the sensitivity of the residual stresses to geometric features and provides a design tool for estimating residual stresses at holes for different geometries....... An example of how to extrapolate the results in terms of far-field stresses is given....

  17. Behavior of a crack within a Dissimilar Metal Weld Part by using an Overlay Weld

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kang Soo; Lee, Ho Jin; Lee, Bong Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-05-15

    In recent years, the dissimilar metal welds, Alloy 82/182 welds, used to connect the stainless steel piping and low alloy steel or carbon steel components in a nuclear reactor piping system have experienced a cracking due to a primary water stress corrosion (PWSCC).It is well known that one reason for the cracking is the residual stress by the weld. But, it is difficult to estimate the weld residual stress exactly due to the many parameters for the welding process. In this paper, a Butt model weld specimen was manufactured and the residual stresses of the weld specimen were measured by the X-Ray method and a Hole Drilling Technique. These results were compared with the results of the Butt FEM Model to confirm the confidence of the FEM input. Also, an analysis of the Crack FEM models made by the ABAQUS Code was performed to estimate the behavior of a crack within a Dissimilar Metal Weld Part (DMWP) when an overlay weld on the DMWP was done.

  18. Ceramic laminates with tailored residual stresses

    Directory of Open Access Journals (Sweden)

    Baudín, C.

    2009-12-01

    Full Text Available Severe environments imposed by new technologies demand new materials with better properties and ensured reliability. The intrinsic brittleness of ceramics has forced scientists to look for new materials and processing routes to improve the mechanical behaviour of ceramics in order to allow their use under severe thermomechanical conditions. The laminate approach has allowed the fabrication of a new family of composite materials with strength and reliability superior to those of monolithic ceramics with microstructures similar to those of the constituent layers. The different ceramic laminates developed since the middle 1970´s can be divided in two large groups depending on whether the development of residual stresses between layers is the main design tool. This paper reviews the developments in the control and tailoring of residual stresses in ceramic laminates. The tailoring of the thickness and location of layers in compression can lead to extremely performing structures in terms of strength values and reliability. External layers in compression lead to the strengthening of the structure. When relatively thin and highly compressed layers are located inside the material, threshold strength, crack bifurcation and crack arrest during fracture occur.

    Las severas condiciones de trabajo de las nuevas aplicaciones tecnológicas exigen el uso de materiales con mejores propiedades y alta fiabilidad. La potencialidad de uso de materiales frágiles, como los cerámicos, en estas aplicaciones exige el desarrollo de nuevos materiales y métodos de procesamiento que mejoren su comportamiento mecánico. El concepto de material laminado ha permitido la fabricación de una nueva familia de materiales con tensiones de fractura y fiabilidad superiores a las de materiales monolíticos con microestructuras similares a las de las láminas que conforman el laminado. Los distintos materiales laminados desarrollados desde mediados de los años 70 se pueden

  19. Effect of Stress Relief Annealing on Microstructure & Mechanical Properties of Welded Joints Between Low Alloy Carbon Steel and Stainless Steel

    Science.gov (United States)

    Nivas, R.; Das, G.; Das, S. K.; Mahato, B.; Kumar, S.; Sivaprasad, K.; Singh, P. K.; Ghosh, M.

    2017-01-01

    Two types of welded joints were prepared using low alloy carbon steel and austenitic stainless steel as base materials. In one variety, buttering material and weld metal were Inconel 82. In another type, buttering material and weld metal were Inconel 182. In case of Inconel 82, method of welding was GTAW. For Inconel 182, welding was done by SMAW technique. For one set of each joints after buttering, stress relief annealing was done at 923 K (650 °C) for 90 minutes before further joining with weld metal. Microstructural investigation and sub-size in situ tensile testing in scanning electron microscope were carried out for buttered-welded and buttered-stress relieved-welded specimens. Adjacent to fusion boundary, heat-affected zone of low alloy steel consisted of ferrite-pearlite phase combination. Immediately after fusion boundary in low alloy steel side, there was increase in matrix grain size. Same trend was observed in the region of austenitic stainless steel that was close to fusion boundary between weld metal-stainless steel. Close to interface between low alloy steel-buttering material, the region contained martensite, Type-I boundary and Type-II boundary. Peak hardness was obtained close to fusion boundary between low alloy steel and buttering material. In this respect, a minimum hardness was observed within buttering material. The peak hardness was shifted toward buttering material after stress relief annealing. During tensile testing no deformation occurred within low alloy steel and failure was completely through buttering material. Crack initiated near fusion boundary between low alloy steel-buttering material for welded specimens and the same shifted away from fusion boundary for stress relieved annealed specimens. This observation was at par with the characteristics of microhardness profile. In as welded condition, joints fabricated with Inconel 82 exhibited superior bond strength than the weld produced with Inconel 182. Stress relief annealing

  20. The mechanical measuring method of welding heat source efficiency

    Institute of Scientific and Technical Information of China (English)

    Zhang Jianqiang; Zhang Guodong; He Jie; Wang Chengquan; Chen Bingquan

    2007-01-01

    Based on the principle of residual deformation induced by superposition of the welding residual stress and working stress, the welding heat source efficiency has been determined by measuring displacement changes of specimens under loading and unloading in tensile tests, and combining with calculating welding parameters. Meanwhile, the welding heat source efficiencies obtained are compared with those of the measuring-calculating method. The research results show that the welding heat source efficiencies are almost the same as those obtained by the measuring-calculating method. Therefore, the welding heat source efficiency can be determined accurately by this method, and a new determining method of the heat source efficiency for the welding heat process calculating has been provided.

  1. A Review on Solidification and Change in Mechanical Properties Under Vibratory Welding Condition

    Directory of Open Access Journals (Sweden)

    Jyoti Prakash

    2010-04-01

    Full Text Available Welding has been applied to various industries in particular, automotive, aerospace and microelectronics. Thermal cycle produced near weld line generates residual stress and inhomogeneous plastic deformation in weldments. However there are many methods for welding the workpieces and one of the method among these is vibratory welding. It has the advantages of less investment, more convenient operation, less pollution and shorter manufacturing period. In vibratory welding, workpiece vibrates in the whole welding process and it mainly effects the welding solidification to improve the quality. Vibration facilitates the release of dissolved gases and the resulting weld beads greatly exhibit reduced porosity. Mechanical properties of the welds prepared under vibratory conditions are dependent on the structural changes of the welds This paper presents the solidification behaviour and changes occurs in mechanical properties under vibratory welding condition.

  2. TIG-dressing of High Strength Butt Welded Connection. Part 2: Physical Testing and Modelling

    OpenAIRE

    Van Es, S.H.J.; Kolstein, M.H.; Pijpers, R.J.M.; Bijlaard, F.S.K.

    2014-01-01

    Weld improvement techniques are aimed at reducing the notch effects of welds and generally focus on two aspects: a change of geometry of the weld toe and a change of the weld residual stresses. In this paper, fatigue tests are discussed, performed on butt welded specimens in steel grades ranging from S460 to S1100 in the TIG-dressed condition. The test results are compared with modelled fatigue strength according to the notch stress theory and similar specimens in the as-welded condition. The...

  3. Residual stresses and their effects in composite laminates

    Science.gov (United States)

    Hahn, H. T.; Hwang, D. G.

    1983-01-01

    Residual stresses in composite laminates are caused by the anisotropy in expansional properties of constituent unidirectional plies. The effect of these residual stresses on dimensional stability is studied through the warping of unsymmetric (0 sub 4/90 sub 4)sub T graphite/epoxy laminates while their effect on ply failure is analyzed for (0/90)sub 2s Kevlar 49/epoxy laminate. The classical laminated plate theory is used to predict the warping of small and large panels. The change of warping does not indicate a noticeable stress relaxation at 75 C while it is very sensitive to moisture content and hence to environment. A prolonged gellation at the initial cure temperature reduces residual stresses while postcure does not. The matrix/interface cracking in dry (0/90)sub 2s Kevlar 49/epoxy laminate is shown to be the result of the residual stress exceeding the transverse strength.

  4. Residual stresses in cross-ply composite tubes

    Science.gov (United States)

    Cohen, D.; Hyer, M. W.

    1984-01-01

    The residual thermal stresses in 4-layer cross-ply tubes are studied. The tubes considered has a small radius to wall-thickness ratios and so elasticity solutions were used. The residual thermal stress problem was considered to be axisymmetric and three elasticity solutions were derived and the results compared with the results using classical lamination theory. The comparison illustrates the limitations of classical lamination theory. The three elasticity solutions derived were: plane stress, plane strain, and generalized plane strain, the latter being the most realistic. Residual stresses in both the hoop and axial direction is significant. Stacking arrangement effects the residual stress to some extent, as do the material properties of the individual lamina. The benefits of hybrid construction are briefly discussed.

  5. Welding Distortion Control of Thin A1 Alloy Plate by Static Thermal Tensioning

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The mechanism and effectiveness of welding distortion mitigation by static thermal tensioning were investigated by both finite element analysis and experiments. It shows that preset thermal tensioning can reduce longitudinal plastic compression remained in the weld and its adjacent zone significantly, so decrease the longitudinal residual stress and the susceptibility to welding distortion.

  6. Water aging reverses residual stresses in hydrophilic dental composites.

    Science.gov (United States)

    Park, J W; Ferracane, J L

    2014-02-01

    Dental composites develop residual stresses during polymerization due to shrinkage. These stresses may change with time because of relaxation and water sorption in the oral environment. This phenomenon is likely dependent on the composition of the materials, specifically their hydrophilic characteristics, and could result in deleterious stresses on restorative materials and tooth structure. The purpose of this experiment was to use the thin ring-slitting method to compare the residual stress generated within composite materials of varying hydrophilicity when aged in wet and dry conditions after polymerization. Water sorption, solubility, elastic modulus, and residual stresses were measured in 6 commercial composites/cements aged in water and dry conditions. The self-adhesive resin cement showed the highest water sorption and solubility. All composites showed initial residual contraction stresses, which were maintained when aged dry. Residual stresses in 2 of the self-adhesive cements and the polyacid-modified composite aged in wet conditions resulted in a net expansion. This experiment verified that residual shrinkage stresses in dental composites can be reversed during aging in water, resulting in a net expansion, with the effect directly related to their hydrophilic properties.

  7. 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.

  8. A new method for welding aluminum alloy LY12CZ sheet with high strength

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    From the viewpoint of welding mechanics, a new welding technology-trailing peening was applied firstly to weld aluminum alloy LY12CZ sheet with high susceptibility to hot cracking. Trailing peening can exert a transverse extrusion strain on the metal in brittle temperature region (BTR) which can compensate for the tensioning strain during the cooling procedure post welding. So, welding hot cracking of LY12CZ sheet can be controlled effectively on the special jig for hot cracking experiment, and the phenomenon of hot cracking can't be found in specimens with large dimensions finally. At the same time, welding with trailing peening can decrease welding distortion caused by longitudinal and transverse shrinkage of weld obviously. Due to strengthening the poor position-weld toe during the process of welding, the residual stress distribution of welded joint is more reasonable. Contrast with conventional welding, mechanical properties such as tensile strength, prolongation ratio and cold-bending angle of welded joint with trailing peening can be improved obviously, and rupture position of welded joint transits from weld toe at conventional welding to weld metal at trailing peening. So, welding with trailing peening can be regarded as a dynamic welding method with low stress, little distortion and hot cracking-free really. As far as theoretical analysis is concerned, the technology of trailing peening can be used to weld the materials with high susceptibility to hot cracking such as LY12CZ and LD10, and solve the welding distortion of thin plate-shell welded structures which contain closed welds such as flange. In addition, the technology of trailing peening has many advantages: simple device, high efficiency, low cost and flexible application which make the welding method have widely applied foreground in the field of aeronautics and aerospace.

  9. 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.

  10. Thermal Recovery of Plastic Deformation in Dissimilar Metal Weld

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Dongxiao [Tsinghua Univ., Beijing (China); Yu, Xinghua [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhang, Wei [The Ohio State Univ., Columbus, OH (United States); Crooker, Paul [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); David, Stan A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Feng, Zhili [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-05-23

    Stainless steel has been widely used in challenging environments typical to nuclear power plant structures, due its excellent corrosion resistance. Nickel filler metals containing high chromium concentration, including Alloy 82/182, are used for joining stainless steel to carbon steel components to achieve similar high resistance to stress corrosion cracking. However, the joint usually experience weld metal stress corrosion cracking (SCC), which affects the safety and structural integrity of light water nuclear reactor systems. A primary driving force for SCC is the high tensile residual stress in these welds. Due to large dimension of pressure vessel and limitations in the field, non-destructive residual stress measurement is difficult. As a result, finite element modeling has been the de facto method to evaluate the weld residual stresses. Recent studies on this subject from researchers worldwide report different residual stress value in the weldments [5]. The discrepancy is due to the fact that most of investigations ignore or underestimate the thermal recovery in the heat-affect zone or reheated region in the weld. In this paper, the effect of heat treatment on thermal recovery and microhardness is investigated for materials used in dissimilar metal joint. It is found that high equivalent plastic strains are predominately accumulated in the buttering layer, the root pass, and the heat affected zone, which experience multiple welding thermal cycles. The final cap passes, experiencing only one or two welding thermal cycles, exhibit less plastic strain accumulation. Moreover, the experimental residual plastic strains are compared with those predicted using an existing weld thermo-mechanical model with two different strain hardening rules. The importance of considering the dynamic strain hardening recovery due to high temperature exposure in welding is discussed for the accurate simulation of weld residual stresses and plastic strains. In conclsuion, the

  11. Application of magnetic Barkhausen noise in non-destructive testing fields of residual stress

    Institute of Scientific and Technical Information of China (English)

    Yin Hechi; Zhang Guangye; Chen Ligong; Ni Chunzhen

    2007-01-01

    Magnetic Barkhausen noise (MBN) is a phenomenon of electromagnetic energy due to the movement of magnetic domain walls inside ferromagnetic materials when they are locally magnetized by an alternating magnetic fields. According to Faraday's law of electromagnetic induction, the noise can be received by the coil attached to the surface of the material being magnetized and the noise carries the message of the characteristics of the material such as stresses, hardness, phase content, etc. Based on the characteristic of the noise, researching about the relationship between the residual stress in the welding assembly and the noise are carried out. Furthermore, data process is performed by RMS (Root Mean Square) equation and Power Spectrum analysis.

  12. 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....

  13. Ultrasonic measurement of residual stress in shot peened aluminum alloy

    Science.gov (United States)

    Lavrentyev, Anton I.; Veronesi, William A.

    2001-04-01

    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 non-destructively evaluate the near surface residual stress would greatly aid the assurance of proper fatigue life in shot-peened components. This paper addresses issues encountered in near-surface residual stress measurement by an ultrasonic surface wave method. In this method, a variation of ultrasonic surface wave speed with shot peening intensity is measured. Since the effective wave penetration depth inversely related to the excitation frequency, by making measurements at different frequencies, the 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 from 4A-16A. Several factors were found to contribute to the measured responses: surface roughness, near surface texture change, dislocation density increase and residual stress. In this paper, the contributions of residual stress, dislocation density and surface roughness to the overall effect are separately estimated. It is shown that the experimentally observed velocity change in shot peened samples is dominated by the effect of surface roughness while the role of residual stress is much smaller.

  14. 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.

  15. Braze welding of cobalt with a silver–copper filler

    Directory of Open Access Journals (Sweden)

    Everett M. Criss

    2015-01-01

    Full Text Available A new method of joining cobalt by braze-welding it with a silver–copper filler was developed in order to better understand the residual stresses in beryllium–aluminum/silicon weldments which are problematic to investigate because of the high toxicity of Be. The base and filler metals of this new welding system were selected to replicate the physical properties, crystal structures, and chemical behavior of the Be–AlSi welds. Welding parameters of this surrogate Co–AgCu system were determined by experimentation combining 4-point bending tests and microscopy. Final welds are 5 pass manual TIG (tungsten inert gas, with He top gas and Ar back gas. Control of the welding process produces welds with full penetration melting of the cobalt base. Microscopy indicates that cracking is minimal, and not through thickness, whereas 4-point bending shows failure is not by base-filler delamination. These welds improve upon the original Be–AlSi welds, which do not possess full penetration, and have considerable porosity. We propose that utilization of our welding methods will increase the strength of the Be–AlSi weldments. The specialized welding techniques developed for this study may be applicable not only for the parent Be–AlSi welds, but to braze welds and welds utilizing brittle materials in general. This concept of surrogacy may prove useful in the study of many different types of exotic welds.

  16. INFLUENCE OF BLADES' STRESS STATE ON FRANCIS TURBINE RUNNER'S INVALIDATION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Numerical simulation on Francis turbine runner's welding temperature field and welding stress field is carried out on the base of solving the problem of welding heat source's movement along any spatial routes and the problem of heat elimination between the complicated blade and air. The evolvement law of welding stress and the distribution of the stress field after welding are obtained.The results indicate that the peak value of the welding residual stress appears on the outlet edge of blade near the contact area between blade and band or blade and crown. Associated with the distribution of the runner's working stress, the invalidation reason of the Francis turbine runner is explained.

  17. Cold compression residual stress reduction in aluminium alloy 7010

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, D.A. [Limerick Univ. (Ireland). Materials Research Centre; Robinson, J.S. [Dept. of Materials Science and Technology, Univ. of Limerick (Ireland); Cudd, R.L. [HDA Forgings Ltd., Redditch, Worchestershire (United Kingdom)

    2000-07-01

    7010 is one of the high strength aluminium alloys used mainly as plate and forgings in the aerospace industry. Its high strength is achieved through a quenching operation where the material is rapidly cooled from the solution heat treatment temperature (475 C) to room temperature. As with all rapid quenching operations, residual stresses develop, leaving the material unsuitable for further machining operations and for service. Regular shaped forgings are generally cold compressed after quenching to relieve residual stresses. The effect of friction, increasing/decreasing the amount of cold compression and applying cold compression in 'bites' on residual stress magnitudes is unknown. This paper aims to study the effect that these variables have on final residual stress patterns through use of a finite element model. (orig.)

  18. Laser cutting of thick sheet metals: Residual stress analysis

    Science.gov (United States)

    Arif, A. F. M.; Yilbas, B. S.; Aleem, B. J. Abdul

    2009-04-01

    Laser cutting of tailored blanks from a thick mild steel sheet is considered. Temperature and stress field in the cutting sections are modeled using the finite element method. The residual stress developed in the cutting section is determined using the X-ray diffraction (XRD) technique and is compared with the predictions. The structural and morphological changes in the cut section are examined using the optical microscopy and scanning electron microscopy (SEM). It is found that temperature and von Mises stress increase sharply in the cutting section, particularly in the direction normal to the cutting direction. The residual stress remains high in the region close to the cutting section.

  19. Residual stress in glass: indentation crack and fractography approaches.

    Science.gov (United States)

    Anunmana, Chuchai; Anusavice, Kenneth J; Mecholsky, John J

    2009-11-01

    To test the hypothesis that the indentation crack technique can determine surface residual stresses that are not statistically significantly different from those determined from the analytical procedure using surface cracks, the four-point flexure test, and fracture surface analysis. Soda-lime-silica glass bar specimens (4 mm x 2.3 mm x 28 mm) were prepared and annealed at 650 degrees C for 30 min before testing. The fracture toughness values of the glass bars were determined from 12 specimens based on induced surface cracks, four-point flexure, and fractographic analysis. To determine the residual stress from the indentation technique, 18 specimens were indented under 19.6N load using a Vickers microhardness indenter. Crack lengths were measured within 1 min and 24h after indentation, and the measured crack lengths were compared with the mean crack lengths of annealed specimens. Residual stress was calculated from an equation developed for the indentation technique. All specimens were fractured in a four-point flexure fixture and the residual stress was calculated from the strength and measured crack sizes on the fracture surfaces. The results show that there was no significant difference between the residual stresses calculated from the two techniques. However, the differences in mean residual stresses calculated within 1 min compared with those calculated after 24h were statistically significant (p=0.003). This study compared the indentation technique with the fractographic analysis method for determining the residual stress in the surface of soda-lime-silica glass. The indentation method may be useful for estimating residual stress in glass.

  20. Corner Crack Propagation in the Presence of Residual Stresses (Preprint)

    Science.gov (United States)

    2006-05-01

    used to produce compressive residual stresses in regions of a component, such as a bolt hole or blade attachment, that were prone to crack...plasticity burnishing (LPB), have been developed more recently to provide ways of inducing deeper compressive residual stresses while limiting surface...experiments performed for this work were designed to simulate fastener holes like those found in turbine engine components. A double-edge notch tension

  1. The Effect of Ultrasonic Peening Treatment on Fatigue Performance of Welded Joints

    Directory of Open Access Journals (Sweden)

    Xiaohui Zhao

    2016-06-01

    Full Text Available Ultrasonic peening treatment (UPT as a method of severe plastic deformation was used to treat cruciform welded joints of Q345 steel. The application of UPT achieves material surface nanocrystallization of the peening zone, reduces stress concentration, and produces residual compressive stresses at the welded toe. Micro-structure, hardness, stress relief, S-N curve, and the fatigue fracture mechanism of cruciform welded joint of Q345 steel, both before and after UPT, were analyzed in detail. The main results show that: stress concentration and residual tensile stress are the main reasons to reduce fatigue strength of cruciform welded joints. The fatigue life of cruciform welded joints is improved for surface hardening, compressive stress, and grain refinement by UPT. Residual compressive stress caused by UPT is released with the increase of fatigue life. A very significant fatigue strength improvement happens when UPT is replenished repeatedly after a certain number of cycles.

  2. 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...

  3. Expanded austenite, crystallography and residual stress

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Hummelshøj, Thomas Strabo; Somers, Marcel A. J.

    2010-01-01

    compositions and (b) unravelling of the contributions of stress-depth and composition-depth profiles in expanded austenite layers are summarised and discussed. It is shown through simulation of line profiles that the combined effects of composition gradients, stress gradients and stacking fault gradients can...

  4. Stress corrosion cracking in canistered waste package containers: Welds and base metals

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J.S.

    1998-03-01

    The current design of waste package containers include outer barrier using corrosion allowable material (CAM) such as A516 carbon steel and inner barrier of corrosion resistant material (CRM) such as alloy 625 and C22. There is concern whether stress corrosion cracking would occur at welds or base metals. The current memo documents the results of our analysis on this topic.

  5. Material properties of a dissimilar metal weld Inconel 600/ Inconel 82 weld filler/ Carbon Steel (Gr.106 B)

    Energy Technology Data Exchange (ETDEWEB)

    Knapp, S. [Univ. of Ottawa, Ottawa, Ontario (Canada); Duan, X. [CANDU Energy Inc., Mississauga, Ontario (Canada); Weck, A., E-mail: aweck@uottawa.ca [Univ. of Ottawa, Ottawa, Ontario (Canada)

    2012-07-01

    Inconel 600 pipes welded to Carbon-Steel are used in CANDU nuclear reactors. Fracture of these welded pipes has important consequences in term of safety, and therefore their mechanical properties need to be better understood. In this study, the weld region was analyzed at various length-scales using optical microscopy, micro hardness testing, small and large scale tensile testing, and Digital Image Correlation (DIC). Micro-hardness profiles showed variations across the weld and through thickness and were justified in terms of residual stresses. Local stress-strain curves were built using DIC and showed good agreement with stress-strain curves obtained from miniature tensile samples. (author)

  6. Residual stresses in non-symmetrical carbon/epoxy laminates

    NARCIS (Netherlands)

    Wijskamp, S.; Akkerman, R.; Lamers, E.A.D.

    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 result

  7. 焊接工艺对奥氏体不锈钢应力腐蚀行为的影响%Effect of Welding Procedure on Stress Corrosion of Austenitic Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    赵尔冰; 张亦良; 陈鴒志

    2011-01-01

    It is difficult to release residual stress for welding of austenitic stainless steel, therefore, its chlorine stress corrosion always occurs in engineering. The stress corrosion testing was done on different welding procedures of three different materials (304, 316 L of China, and 304 of German). The welding procedure includes shielded metal arc welding and flux cored CO2 shielded are welding through air cooling and water cooling after welding. The base metal, starting point and ending point of welding arc were tested. The better procedure is obtained through 100 samples, and the stress-life relationship of stress corrosion in boiled MgCl2 of two types of materials are formulated. The conclusion is that life of stress corrosion of 316 L is 15 times of 304, life of the starting point is longer than the ending point of welding arc, life of the butt weld is longer than the fillet weld, and faster cooling after welding is efficient for life of stress corrosion.%针对氯离子环境中奥氏体不锈钢焊缝较高的焊接残余应力极易引发应力腐蚀开裂的普遍性工程难题,对国产304、316L、德国304钢3种材料的不同焊接工艺进行了系列应力腐蚀实验研究.焊接工艺包括手工焊条电弧焊及CO2保护药芯电弧焊、焊后空冷及浇水速冷,取样位置包括母材、焊缝起弧及收弧.通过100多个试样的应力腐蚀对比实验,研究了各种工艺之间的优劣,拟合了2种材料在沸腾氯化镁环境中应力一寿命的数学关系.结果表明,对应力腐蚀寿命而言,316L是304钢的15倍以上、焊接起弧点高于收弧点、对接焊缝高于角焊缝;焊后速冷工艺可提高焊接接头抗应力腐蚀能力.

  8. 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)

  9. Propagation of dissection in a residually-stressed artery model.

    Science.gov (United States)

    Wang, Lei; Roper, Steven M; Hill, Nicholas A; Luo, Xiaoyu

    2017-02-01

    This paper studies dissection propagation subject to internal pressure in a residually-stressed two-layer arterial model. The artery is assumed to be infinitely long, and the resultant plane strain problem is solved using the extended finite element method. The arterial layers are modelled using the anisotropic hyperelastic Holzapfel-Gasser-Ogden model, and the tissue damage due to tear propagation is described using a linear cohesive traction-separation law. Residual stress in the arterial wall is determined by an opening angle [Formula: see text] in a stress-free configuration. An initial tear is introduced within the artery which is subject to internal pressure. Quasi-static solutions are computed to determine the critical value of the pressure, at which the dissection starts to propagate. Our model shows that the dissection tends to propagate radially outwards. Interestingly, the critical pressure is higher for both very short and very long tears. The simulations also reveal that the inner wall buckles for longer tears, which is supported by clinical CT scans. In all simulated cases, the critical pressure is found to increase with the opening angle. In other words, residual stress acts to protect the artery against tear propagation. The effect of residual stress is more prominent when a tear is of intermediate length ([Formula: see text]90[Formula: see text] arc length). There is an intricate balance between tear length, wall buckling, fibre orientation, and residual stress that determines the tear propagation.

  10. Determination of Residual Stress in Composite Materials Using Ultrasonic Waves

    Science.gov (United States)

    Rokhlin, S. I.

    1997-01-01

    The performance of high temperature composites can be significantly affected by the presence of residual stresses. These stresses arise during cooling processes from fabrication to room temperature due to mismatch of thermal expansion coefficients between matrix and fiber materials. This effect is especially pronounced in metal matrix and intermetallic composites. It can lead to plastic deformations, matrix cracking and fiber/matrix interface debonding. In this work the feasibility of ultrasonic techniques for residual stress assessment in composites is addressed. A novel technique for absolute stress determination in orthotropic materials from angular dependencies of ultrasonic velocities is described. The technique is applicable for determination of both applied and residual stresses and does not require calibration measurements on a reference sample. The important advantage of this method is that stress is determined simultaneously with stress-dependent elastic constants and is thus decoupled from the material texture. It is demonstrated that when the principal plane stress directions coincide with acoustical axes, the angular velocity data in the plane perpendicular to the stress plane may be used to determine both stress components. When the stress is off the acoustical axes, the shear and the difference of the normal stress components may be determined from the angular dependence of group velocities in the plane of stresses. Synthetic sets of experimental data corresponding to materials with different anisotropy and stress levels are used to check the applicability of the technique. The method is also verified experimentally. A high precision ultrasonic wave transmission technique is developed to measure angular dependence of ultrasonic velocities. Examples of stress determination from experimental velocity data are given. A method is presented for determination of velocities of ultrasonic waves propagating through the composite material with residual

  11. Determination of residual stresses in sintered ceramics. A hypoelastic model

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, F. (Advanced Materials Engineering Centre, Halifax, NS (Canada)); Murphy, J.G. (General Compiste Technology, Halifax, NS (Canada))

    1991-04-01

    The ceramic firing cycles necessary for sintering often produce high thermal gradients. Such thermal cycles, especially in materials with low thermal conductivity, can cause different densification rates. The result of such mechanical nonuniformity is the formation of residual stress patterns in the materials. The magnitude of these stresses is sufficient to cause microcracks to occur. In this study, a practical and versatile methodology used in evaluating the residual stresses resulting from mechanical nonuniformity in slip cast ceramics will be discussed. The analysis uses the commercial finite element program ABAQUS in conjunction with a hypoelastic material constitutive model. The qualitative results obtained from the preliminary finite element method (FEM) investigations illustrate that this numerical methodology can be used to emulate the sintering mechanism, and estimate the residual stresses caused by sintering processes. (orig.).

  12. 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.

  13. Characterization of 2.25Cr1Mo welded ferritic steel plate by using diffractometric and ultrasonic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Cernuschi, F.; Ghia, S. [Ente Nazionale per l`Energia Elettrica, Milan (Italy); Albertini, G.; Ceretti, M.; Rustichelli, F. [Ancona Univ. (Italy). Ist. di Fisica Medica; Castelnuovo, A.; Depero, L. [Univ. degli studi, Brescia.Fac. di ingegneria, dip. di ingegneria meccanica (Italy); Giamboni, S.; Gori, M. [Centro Elettrotecnico Sperimentale Italiano (CESI), Milan (Italy)

    1995-12-01

    Four different techniques (X-ray and neutron diffraction, ultrasonic birefringence and incremental hole drilling method) were applied for evaluating residual stress in a butt-welded ferritic steel palte. Measurements were carried out both before and after welding. Effects of post-welding heat treatment is also considered. A comparison between results obtained by using four different techniques is done.

  14. Development of a comprehensive weld process model

    Energy Technology Data Exchange (ETDEWEB)

    Radhakrishnan, B.; Zacharia, T.; Paul, A.

    1997-05-01

    This cooperative research and development agreement (CRADA) between Concurrent Technologies Corporation (CTC) and Lockheed Martin Energy Systems (LMES) combines CTC`s expertise in the welding area and that of LMES to develop computer models and simulation software for welding processes. This development is of significant impact to the industry, including materials producers and fabricators. The main thrust of the research effort was to develop a comprehensive welding simulation methodology. A substantial amount of work has been done by several researchers to numerically model several welding processes. The primary drawback of most of the existing models is the lack of sound linkages between the mechanistic aspects (e.g., heat transfer, fluid flow, and residual stress) and the metallurgical aspects (e.g., microstructure development and control). A comprehensive numerical model which can be used to elucidate the effect of welding parameters/conditions on the temperature distribution, weld pool shape and size, solidification behavior, and microstructure development, as well as stresses and distortion, does not exist. It was therefore imperative to develop a comprehensive model which would predict all of the above phenomena during welding. The CRADA built upon an already existing three-dimensional (3-D) welding simulation model which was developed by LMES which is capable of predicting weld pool shape and the temperature history in 3-d single-pass welds. However, the model does not account for multipass welds, microstructural evolution, distortion and residual stresses. Additionally, the model requires large resources of computing time, which limits its use for practical applications. To overcome this, CTC and LMES have developed through this CRADA the comprehensive welding simulation model described above.

  15. Stress corrosion cracking of austenitic weld deposits in a salt spray environment

    Science.gov (United States)

    Cai, J. B.; Yu, C.; Shiue, R. K.; Tsay, L. W.

    2015-10-01

    ER 308L and 309LMo were utilized as the filler metals for the groove and overlay welds of a 304L stainless steel substrate, which was prepared via a gas tungsten arc-welding process in multiple passes. U-bend and weight-loss tests were conducted by testing the welds in a salt spray containing 10 wt% NaCl at 120 °C. The dissolution of the skeletal structure in the fusion zone (FZ) caused the stress corrosion cracking (SCC) of the weld. The FZ in the cold-rolled condition showed the longest single crack length in the U-bend tests. Moreover, sensitization treatment at 650 °C for 10 h promoted the formation of numerous fine cracks, which resulted in a high SCC susceptibility. The weight loss of the deposits was consistent with the SCC susceptibility of the welds in a salt spray. The 309LMo deposit was superior to the 308L deposit in the salt spray.

  16. Analysis of welding distortion due to narrow-gap welding of upper port plug

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Pankaj, E-mail: panu012@yahoo.co.i [Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology, Kharagpur, Pin 721302 (India); Mandal, N.R., E-mail: nrm@naval.iitkgp.ernet.i [Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology, Kharagpur, Pin 721302 (India); Vasu, Parameswaran, E-mail: parameswaran.vasu@iter-india.or [ITER-India, Institute of Plasma Research, Ahmedabad (India); Padasalag, Shrishail B., E-mail: subhasis.panja@iter-india.or [ITER-India, Institute of Plasma Research, Ahmedabad (India)

    2010-08-15

    Narrow-gap welding is a low distortion welding process. This process allows very thick plates to be joined using fewer weld passes as compared to conventional V-groove or double V-groove welding. In case of narrow-gap arc welding as the heat input and weld volume is low, it reduces thermal stress leading to reduction of both residual stress and distortion. In this present study the effect of narrow-gap welding was studied on fabrication of a scaled down port plug in the form of a trapezoidal box made of 10 mm thick mild steel (MS) plates using gas tungsten arc welding (GTAW). Inherent strain method was used for numerical prediction of resulting distortions. The numerical results compared well with that of the experimentally measured distortion. The validated numerical scheme was used for prediction of weld induced distortion due to narrow-gap welding of full scale upper port plug made of 60 mm thick SS316LN material as is proposed for use in ITER project. It was observed that it is feasible to fabricate the said port plug keeping the distortions minimum within about 7 mm using GTAW for root pass welding followed by SMAW for filler runs.

  17. Local residual stress measurements on nitride layers

    NARCIS (Netherlands)

    Mansilla, C.; Ocelik, V.; De Hosson, J. Th. M.

    2015-01-01

    In this work, local stresses in different nitrided maraging steel samples of high practical interest for industrial applications were studied through the so-called micro-slit milling method using a focused ion beam. The nitrogen concentration profiles were acquired by glow discharge optical emission

  18. 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

  19. Residual circulation and tidal stress in the Gulf of California

    Science.gov (United States)

    Salas-De-León, David Alberto; Carbajal-PéRez, Noel; Monreal-Gómez, Maria Adela; Barrientos-MacGregor, Gerardo

    2003-10-01

    Results of a three-dimensional nonlinear barotropic shelf model are used to study the effect of the M2 tidal stress on the residual current in the Gulf of California. The tidal stress summarizes the nonlinear interactions and forces the residual circulation. It is calculated following the method developed by [1975]. The vertical structure of the tidal stress reveals clearly the zones where the interaction between tidal currents and the basin geometry is strong. The highest values of tidal stress were found over the Salsipuedes sill and in the Ballenas Channel in the central archipelago and in the Colorado River Delta. Relatively high values of tidal stress were also found in deeper layers in the southern part. The high tidal stress values coincide well with the anomalous cold-water patches observed in the archipelago area, attributed to tidal mixing. The calculated residual currents show a maximum of about 15 cm s-1 in the upper layers in the archipelago area. At subsurface layers an anticyclonic circulation is observed. Divergence patterns in the upper layers suggest that M2 tide residuals contribute, to significant upward movements of water, on the west side of Tiburón island. This barotropic process may contribute to the generation of the observed cold patches.

  20. Effects on mechanical properties in electron beam welding of TC4 alloy by laser shock processing

    Institute of Scientific and Technical Information of China (English)

    LU Jinzhong; ZHANG Yongkang; KONG Dejun; REN Xudong; GE Tao; ZOU Shikun

    2007-01-01

    The surface of TC4 titanium alloy welding line by electron beam welding (EBW) was processed by high power Q-switched and repetition-rate Nd: glass laser. Effects of laser power and spot diameter on residual stress and microhardness of the TC4 alloy welding line by laser shock processing (LSP) have been analyzed. Results show that residual stresses almost do not change as laser poweris 45.9 J,spot diameter is φ9 mm; While laser power is 45.9 J, spot diameter less than φ3 mm, the distribution of residual stress in welding line occurs obvious variation, which residual stress increase obviously with spot diameter decrease. When power density is bigger than 1.8×1010W/cm2, residual stresses of electron beam welding line occur change by LSP,which improve obviously residual stress distribution; while laser power is bigger than 1.2×1010W/cm2, the surface micro-hardness of electron beam welding line occurs change by LSP, which improve obviously micro-hardness distribution. Mechanical properties of TC4 titanium alloy welding line will be improved by LSP, which provides experimental foundation for further controlling the distributions of residual stress and micro-hardness during laser shock processing.

  1. Numerical simulation and experimental validation of arc welding of DMR-249A steel

    Directory of Open Access Journals (Sweden)

    Rishi Pamnani

    2016-08-01

    Full Text Available The thermo-mechanical attributes of DMR-249A steel weld joints manufactured by shielded metal arc welding (SMAW and activated gas tungsten arc welding (A-GTAW processes were studied using Finite Element Model (FEM simulation. The thermal gradients and residual stresses were analyzed with SYSWELD software using double ellipsoidal heat source distribution model. The numerically estimated temperature distribution was validated with online temperature measurements using thermocouples. The predicted residual stresses profile across the weld joints was compared with the values experimentally measured using non-destructive techniques. The measured and predicted thermal cycles and residual stress profile was observed to be comparable. The residual stress developed in double sided A-GTAW joint were marginally higher in comparison to five pass SMAW joint due to phase transformation associated with high heat input per weld pass for A-GTAW process. The present investigations suggest the applicability of numerical modeling as an effective approach for predicting the thermo-mechanical properties influenced by welding techniques for DMR-249A steel weld joints. The tensile, impact and micro-hardness tests were carried to compare the welds. Considering benefits of high productivity and savings of labor and cost associated with A-GTAW compared to SMAW process, the minor variation in residual stress build up of A-GTAW joint can be neglected to develop A-GTAW as qualified alternative welding technique for DMR-249A steel.

  2. Residual stresses in injection molded shape memory polymer parts

    Science.gov (United States)

    Katmer, Sukran; Esen, Huseyin; Karatas, Cetin

    2016-03-01

    Shape memory polymers (SMPs) are materials which have shape memory effect (SME). SME is a property which has the ability to change shape when induced by a stimulator such as temperature, moisture, pH, electric current, magnetic field, light, etc. A process, known as programming, is applied to SMP parts in order to alter them from their permanent shape to their temporary shape. In this study we investigated effects of injection molding and programming processes on residual stresses in molded thermoplastic polyurethane shape memory polymer, experimentally. The residual stresses were measured by layer removal method. The study shows that injection molding and programming process conditions have significantly influence on residual stresses in molded shape memory polyurethane parts.

  3. Finite element calculation of residual stress in dental restorative material

    Science.gov (United States)

    Grassia, Luigi; D'Amore, Alberto

    2012-07-01

    A finite element methodology for residual stresses calculation in dental restorative materials is proposed. The material under concern is a multifunctional methacrylate-based composite for dental restorations, activated by visible light. Reaction kinetics, curing shrinkage, and viscoelastic relaxation functions were required as input data on a structural finite element solver. Post cure effects were considered in order to quantify the residual stresses coming out from natural contraction with respect to those debited to the chemical shrinkage. The analysis showed for a given test case that residual stresses frozen in the dental restoration at uniform temperature of 37°C are of the same order of magnitude of the strength of the dental composite material per se.

  4. The Effect of Laser Scan Strategy on Distortion and Residual Stresses of Arches Made With Selective Laser Melting

    Science.gov (United States)

    Bagg, Stacey D.; Sochalski-Kolbus, Lindsay M.; Bunn, Jeffrey R.

    2016-01-01

    The NASA Marshall Space Flight Center (MSFC) is developing Additive Manufacturing (AM) - both in-space AM for on-demand parts, tools, or structures, and on-earth AM for rapid, reduced-cost, small volume production of complex space-flight hardware. Selective Laser Melting (SLM) is an on-earth AM technology that MSFC is using to build Alloy 718 rocket engine components. An understanding of the SLM-718 material properties is required to design, build, and qualify these components for space flight. Residual stresses and are of particular interest for this AM process, since SLM is a series of approximately 100 micron-wide welds, where highly non-linear heating and cooling, severe thermal gradients and repeated thermal cycling can result in high residual stresses within the component. These stresses may cause degraded material properties, and warp or distort the geometry of the SLM component. The distortions can render the component out-of-tolerance when inspected, and even interrupt or halt the build process if the warped material prevents the SLM machine from operating properly. The component must be scrapped and re-designed, which is time consuming and costly. If residual stresses are better understood, and can be predicted, these effects can be mitigated early in the component's design. the compressive residual stresses in the z-direction were highest in the chess sample, followed by island then continuous. This may be due to the binding nature of the segments

  5. Analysis of weld fatigue for steel crane beam based on equivalent structural stress%基于等效结构应力的钢吊车梁焊缝疲劳分析

    Institute of Scientific and Technical Information of China (English)

    张新萍; 唐柏鉴; 王飞

    2016-01-01

    This paper introduces the principle of equivalent structure stress method for weld fatigue evaluation. Taking T type welded joint as an example, the equivalent structural stress method is verified to be non-sensitive to the grid. Then taking a crane beam as the research object, the result of finite element static analysis has been calculated with the equivalent structure stress method by ANSYS/FE-SAFE. Finally, considering the influence of welding residual stress, weld fatigue life has been evaluated. The results show that the fatigue life of the weld is not sensitive, and the residual stress has reduced the fatigue life of the weld seam.%介绍等效结构应力法对焊缝疲劳评定的原理,以T型焊接接头对比验证等效结构应力法具有网格不敏感。然后以某钢吊车梁作为研究对象,对其进行了静力分析,并且利用有限元分析软件ANSYS/FE-SAFE对吊车梁主焊缝进行了评定。最后,考虑焊接残余应力的影响,对焊缝疲劳寿命进行评估。研究表明,基于等效结构应力法进行焊缝疲劳评定得到的疲劳寿命对网格大小不敏感;残余应力的存在降低了焊缝的疲劳寿命。

  6. 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.

  7. Elastic Plastic Stress Distributions in Weld-bonded Lap Joint under Axial Loading

    Directory of Open Access Journals (Sweden)

    Essam A. Al-Bahkali

    2014-06-01

    Full Text Available Weld-bonding process is increasingly used in many industries such like automobile and aerospace. It offers significant improvements of sheet metal joints in static, dynamic, corrosion, noise resistance, stiffness and impact toughness properties. A full understanding of this process, including the elastic-plastic stress distribution in the joint, is a must for joints design and automation of manufacturing. Also, the modelling and analysis of this process, though it is complex, proves to be of prime importance. Thus, in this study a systematic experimental and theoretical study employing Finite Element Analysis (FEA is conducted on the weld-bonded joint, fabricated from Austenitic Stainless steel (AISI 304 sheets of 1.00 mm thickness and Epoxy adhesive Araldite 2011, subjected to axial loading. Complete 3-D finite element models are developed to evaluate the normal, shear and triaxial Von Mises stresses distributions across the entire joint, in both the elastic and plastic regions. The, needed quantities and properties, for the FE modelling and analysis, of the base metals and the adhesive, such like the elastic-plastic properties, modulus of elasticity, fracture limit, the nugget and Heat Affected Zones (HAZ properties, etc., are obtained from the experiments. The stress distribution curves obtained are found to be consistent with those obtained from the FE models and in excellent agreement with the experimental and theoretical published data, particularly in the elastic region. Furthermore, the stress distribution curves obtained for the weld-bonded joint display the best uniform smooth distribution curves compared to those obtained for the spot and bonded joint cases. The stress concentration peaks at the edges of the weld-bonded region, are almost eliminated resulting in achieving the strongest joint.

  8. Simulated Service and Stress Corrosion Cracking Testing for Friction Stir Welded Spun Formed Domes

    Science.gov (United States)

    Stewart, Thomas J.; Torres, Pablo D.; Caratus, Andrei A.; Curreri, Peter A.

    2010-01-01

    Simulated service testing (SST) development was required to help qualify a new 2195 aluminum lithium (Al-Li) alloy spin forming dome fabrication process for the National Aeronautics and Space Administration (NASA) Exploration Development Technology Program. The application for the technology is to produce high strength low weight tank components for NASA s next generation launch vehicles. Since plate material is not currently manufactured large enough to fabricate these domes, two plates are joined by means of friction stir welding. The plates are then pre-contour machined to near final thicknesses allowing for a thicker weld land and anticipating the level of stretch induced by the spin forming process. The welded plates are then placed in a spin forming tool and hot stretched using a trace method producing incremental contours. Finally the dome receives a room temperature contour stretch to final dimensions, heat treatment, quenching, and artificial aging to emulate a T-8 condition of temper. Stress corrosion cracking (SCC) tests were also performed by alternate immersion in a sodium chloride (NaCl) solution using the typical double beam assembly and with 4-point loaded specimens and use of bent-beam stress-corrosion test specimens under alternate immersion conditions. In addition, experiments were conducted to determine the threshold stress intensity factor for SCC (K(sub ISCC)) which to our knowledge has not been determined previously for Al-Li 2195 alloy. The successful simulated service and stress corrosion testing helped to provide confidence to continue to Ares 1 scale dome fabrication

  9. Advanced holographic nondestructive testing system for residual stress analysis

    CERN Document Server

    Kniazkov, Anatoli; Dovgalenko, George; Salamo, Gregory; Latychevskaia, Tatiana; 10.1117/12.347399

    2013-01-01

    The design and operating of a portable holographic interferometer for residual stress analysis by creating a small scratch along with a new mathematical algorithm of calculations are discussed. Preliminary data of the stress investigations on aluminum and steel alloys have been obtained by the automatic processing of the interference pattern using a notebook computer. A phase-shift compensation technique in real-time reflection interferometry is used to measure the out-of-plane stress release surface displacement surrounding a small scratch (25 um depth and 0.5 mm width) in a plate with residual stress of around 50 MPa. Comparison between theoretical models for a rectangular and triangular shaped scratch with the experimental data are presented.

  10. Residual stress characterization with an ultrasonic/magnetic technique

    Science.gov (United States)

    Namkung, M.; Heyman, J. S.

    1984-01-01

    A potentially useful new technique for residual stress characterization in ferromagnetic material is described. The unique feature of this technique is the measurement of small changes in ultrasonic wave velocity by the application of external dc magnetic field in the material under various stress conditions. It was found, in steel, that the fractional change in the natural velocity Delta W/W of waves propagating along the external field direction is affected by the uniaxial stress applied in the same axis. External compression lowers the slope of the Delta W/W curve in the low field region, while external tension generally does the opposite. For most cases, the slope in this region falls below zero under external compression. The result of measurements in specimens with residual stress shows exactly the same tendency.

  11. 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...... 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...... 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...

  12. Structural integrity analyses for preemptive weld overlay on the dissimilar metal weld of a pressurizer nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chin-Cheng, E-mail: cchuang@iner.gov.tw [Institute of Nuclear Energy Research, Taiwan (China); Liu, Ru-Feng [Institute of Nuclear Energy Research, Taiwan (China)

    2012-02-15

    This paper presents structural integrity analyses for preemptive weld overlay on the dissimilar metal weld (DMW) of a pressurizer nozzle in a pressurized water reactor (PWR). Based on MRP-169 and ASME Code Case N-504-2, weld overlay sizing calculation, residual stress improvement, shrinkage evaluation, fatigue crack growth and fatigue usage analysis are performed. The weld overlay procedure has to be confirmed to improve the residual stresses around the inside surface of DMW. The residual compressive stress distribution is thus addressed to be resistant to subsequent primary water stress corrosion cracking (PWSCC) initiation and further crack growth. To ensure the structural integrity of the original attached piping system, the measured displacement is transformed to temperature gradient to simulate the shrinkage after overlay and is used to determine the post weld distortion and stress situation. Further, the conservative postulated surface cracks are assumed in the DMW for fatigue crack growth analysis with system design cycles. The stress limits and cumulative fatigue usages of the pressurizer nozzle with overlay are also evaluated to meet ASME Code, Section III. Based on the present results, the structural integrity of the pressurizer nozzle with preemptive weld overlay is shown.

  13. Thermomechanical Modelling of Friction Stir Welding

    DEFF Research Database (Denmark)

    Hattel, Jesper Henri; Schmidt, Henrik Nikolaj Blicher; Tutum, Cem Celal

    2009-01-01

    Friction Stir Welding (FSW) is a fully coupled thermomechanical process and should in general be modelled as such. Basically, there are two major application areas of thermomechanical models in the investigation of the FSW process: i) Analysis of the thermomechanical conditions such as e.g. heat...... generation and local material deformation (often referred to as flow) during the welding process itself. ii) Prediction of the residual stresses that will be present in the joint structure post to welding. While the former in general will call for a fully-coupled thermomechanical procedure, however...... for the FSW process at hand, the heat generation must either be prescribed analytically or based on a fully coupled analysis of the welding process itself. Along this line, a recently proposed thermal-pseudo-mechanical model is presented in which the temperature dependent yield stress of the weld material...

  14. Laser Peening for Mitigation of Stress Corrosion Cracking at Welds in Marine Aluminum

    Science.gov (United States)

    2011-06-01

    Second Reader: Joseph C. Farmer THIS PAGE INTENTIONALLY LEFT BLANK i REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden...Advisor Joseph C. Farmer Second Reader Knox Millsaps Chair, Department of Mechanical and Aerospace Engineering iv THIS PAGE...Cruisers, in Defense News2010. p. 4. [4] K. N. Tran, M. R. Hill, et al., Welding Journal, 85 (2006) 28. [5] M. G. Fontana , Stress Corrosion, in Corrosion

  15. The impact of the residual stress on the EUV pellicle

    Science.gov (United States)

    Park, Eun-Sang; Choi, Jae-Keun; Kim, Min-Ha; Hwang, Sollee; Shamsi, Zahid Hussain; Kim, Dai-Gyoung; Oh, Hye-Keun

    2016-05-01

    High resolution patterning on the chip could be achieved by extreme ultraviolet lithography (EUVL). However, the defect on the mask becomes more important issue with very short wavelength (13.5 nm). Using the pellicle which could protect the mask from the defects can support high volume manufacturing (HVM). Most of the materials considered for pellicle have relatively high extinction coefficient in EUV region. Therefore, the thickness of the pellicle should be ~ nm thin. The stress of the pellicle is dependent not only on the temperature but also on the mechanical properties of the pellicle. The stress induced by the gravity was small compared to the thermal stress. However, the residual stress should be also considered since it is dependent on the pellicle manufacturing environment and this stress is comparable with the thermal stress. Our result shows the importance of the lowering the pellicle fabrication temperature in terms of the extending the lifetime during the scanning process.

  16. Thermal residual stress analysis of coated diamond grits

    Institute of Scientific and Technical Information of China (English)

    Zi-qian Huang; Bo Xiang; Yue-hui He; Bai-yun Huang

    2009-01-01

    Residual stresses of coated diamond grits were analyzed by a finite element unit cell model.Diamond grits coated with four types of metals, W, Mo, Ti, and Cr, were considered.The numerical results show that compressive stress occurs in the diamond particles and tensile stress occurs in the metal matrix; compressive stress is concentrated in the diamond sharp comer; interface stresses decrease by more than 1000 MPa with a metal interlayer; plastic deformation of the matrix begins near the sharp comer of diamond grits and extends toward the peripheral zone.Stress concentration dramatically decreases due to plastic deformation of the matrix.The deposition of transition metals on a diamond surface can dramatically promote the adhesion between diamond grits and the metal bond.

  17. Thermo-Mechanical Analysis of a Single-Pass Weld Overlay and Girth Welding in Lined Pipe

    Science.gov (United States)

    Obeid, Obeid; Alfano, Giulio; Bahai, Hamid

    2017-08-01

    The paper presents a nonlinear heat-transfer and mechanical finite-element (FE) analyses of a two-pass welding process of two segments of lined pipe made of a SUS304 stainless steel liner and a C-Mn steel pipe. The two passes consist of the single-pass overlay welding (inner lap weld) of the liner with the C-Mn steel pipe for each segment and the single-pass girth welding (outer butt weld) of the two segments. A distributed power density of the moving welding torch and a nonlinear heat-transfer coefficient accounting for both radiation and convection have been used in the analysis and implemented in user subroutines for the FE code ABAQUS. The modeling procedure has been validated against previously published experimental results for stainless steel and carbon steel welding separately. The model has been then used to determine the isotherms induced by the weld overlay and the girth welding and to clarify their influence on the transient temperature field and residual stress in the lined pipe. Furthermore, the influence of the cooling time between weld overlay and girth welding and of the welding speed have been examined thermally and mechanically as they are key factors that can affect the quality of lined pipe welding.

  18. Thermo-Mechanical Analysis of a Single-Pass Weld Overlay and Girth Welding in Lined Pipe

    Science.gov (United States)

    Obeid, Obeid; Alfano, Giulio; Bahai, Hamid

    2017-07-01

    The paper presents a nonlinear heat-transfer and mechanical finite-element (FE) analyses of a two-pass welding process of two segments of lined pipe made of a SUS304 stainless steel liner and a C-Mn steel pipe. The two passes consist of the single-pass overlay welding (inner lap weld) of the liner with the C-Mn steel pipe for each segment and the single-pass girth welding (outer butt weld) of the two segments. A distributed power density of the moving welding torch and a nonlinear heat-transfer coefficient accounting for both radiation and convection have been used in the analysis and implemented in user subroutines for the FE code ABAQUS. The modeling procedure has been validated against previously published experimental results for stainless steel and carbon steel welding separately. The model has been then used to determine the isotherms induced by the weld overlay and the girth welding and to clarify their influence on the transient temperature field and residual stress in the lined pipe. Furthermore, the influence of the cooling time between weld overlay and girth welding and of the welding speed have been examined thermally and mechanically as they are key factors that can affect the quality of lined pipe welding.

  19. On the Eigenstrain Application of Shot-peened Residual Stresses within a Crystal Plasticity Framework: Application to Ni-base Superalloy Specimens (Postprint)

    Science.gov (United States)

    2015-07-08

    public release; distribution unlimited. See additional restrictions described on inside pages STINFO COPY AIR FORCE RESEARCH LABORATORY MATERIALS AND...relate to them. Qualified requestors may obtain copies of this report from the Defense Technical Information Center (DTIC) (http://www.dtic.mil...Tan ML, Ganguly S, Irving PE, Fitzpatrick ME, Zhang X, Edwards L. Weld residual stress effects on fatigue crack growth behaviour of aluminium alloy

  20. finite element model for predicting residual stresses in shielded ...

    African Journals Online (AJOL)

    eobe

    The generated residual stresses were measured using an X. E066 electrodes were used ... direction (σx) had a maximum value of 375MPa (tensile) and minimum value of ... method are in fair agreement with the experimental results. Based on ...

  1. Thermal residual stresses and stress distributions under tensile and compressive loadings of short fiber reinforced metal matrix composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The thermal residual stresses and the stress distributions of short fiber reinforced metal matrix composite under tensile and compressive loadings were studied using large strain axisymmetric elasto-plastic finite element method. It is demonstrated that the thermal residual stresses can result in asymmetrical stress distributions and matrix plasticity. The thermal residual stresses decrease the stress transfer in tension and enhance the stress transfer in compression. The fiber volume fraction has more important effects on the thermal residual stresses and the stress distributions under tensile and compressive loadings than the fiber aspect ratio and the fiber end distance.

  2. Damage Tolerance Assessment of Friction Pull Plug Welds in an Aluminum Alloy

    Science.gov (United States)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process used in the fabrication of cryogenic propellant tanks. Self-reacting friction stir welding is one variation of the friction stir weld process being developed for manufacturing tanks. Friction pull plug welding is used to seal the exit hole that remains in a circumferential self-reacting friction stir weld. A friction plug weld placed in a self-reacting friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data relating residual strength capability to flaw size in an aluminum alloy friction plug weld will be presented.

  3. Measurement of the Residual Stresses and Investigation of Their Effects on a Hardfaced Grid Plate due to Thermal Cycling in a Pool Type Sodium-Cooled Fast Reactor

    Directory of Open Access Journals (Sweden)

    S. Balaguru

    2016-01-01

    Full Text Available In sodium-cooled fast reactors (SFR, grid plate is a critical component which is made of 316 L(N SS. It is supported on core support structure. The grid plate supports the core subassemblies and maintains their verticality. Most of the components of SFR are made of 316 L(N/304 L(N SS and they are in contact with the liquid-metal sodium which acts as a coolant. The peak operating temperature in SFR is 550°C. However, the self-welding starts at 500°C. To avoid self-welding and galling, hardfacing of the grid plate has become necessary. Nickel based cobalt-free colmonoy 5 has been identified as the hardfacing material due to its lower dose rate by Plasma Transferred Arc Welding (PTAW. This paper is concerned with the measurement and investigations of the effects of the residual stress generated due to thermal cycling on a scale-down physical model of the grid plate. Finite element analysis of the hardfaced grid plate model is performed for obtaining residual stresses using elastoplastic analysis and hence the results are validated. The effects of the residual stresses due to thermal cycling on the hardfaced grid plate model are studied.

  4. Cold Cracking of Flux Cored Arc Welded Armour Grade High Strength Steel Weldments

    Institute of Scientific and Technical Information of China (English)

    G.Magudeeswaran; V.Balasubramanian; G.Madhusudhan Reddy

    2009-01-01

    In this investigation, an attempt has been made to study the influence of welding consumables on the factors that influence cold cracking of armour grade quenched and tempered (Q&T) steel welds. Flux cored arc welding (FCAW) process were used making welds using austenitic stainless steel (ASS) and low hydrogen ferritic steel (LHF) consumables. The diffusible hydrogen levels in the weld metal of the ASS and LHF consumables were determined by mercury method. Residual stresses were evaluated using X-ray stress analyzer and implant test was carried out to study the cold cracking of the welds. Results indicate that ASS welds offer a greater resistance to cold cracking of armour grade Q&T steel welds.

  5. Technique for the residual life assessment of high temperature components based on creep-rupture testing on welded miniature specimens

    Energy Technology Data Exchange (ETDEWEB)

    Garzillo, A.; Guardamagna, C.; Moscotti, L.; Ranzani, L. [Ente Nazionale per l`Energia Elettrica, Milan (Italy)

    1995-06-01

    Following the present trend in the development of advanced methodologies for residual life assessment of high temperature components operating in power plants, particularly in non destructive methods, a testing technique has been set up at ENEL-CRAM based on creep-rupture testa in an argon on welded miniature specimens. Five experimental systems for creep-rupture tests in an argon atmosphere have been set up which include high accuracy systems, vacuum chambers and exrwnsometer devices. With the aim of establishing and validating the suitability of the experimental methodology, creep-rupture and interrupted creep testing programmes have been performed on miniature specimens (2 mm diameter and 10 mm gauge lenght). On the basis of experience gathered by various European research laboratories, a miniature specimen construction procedure has been developed using a laser welding technique for joining threaded heads to sample material. Low alloy ferritic steels, such as virgin 2.25CrlMo, 0.5Cr 0.5Mo 0.25V, and IN 738 superalloy miniature specimens have been investigated and the results, compared with those from standard specimens, show a regular trend in deformation vs time. Additional efforts to provide guidelines for material sampling from each plant component will be required in order to reduce uncertainties in residual life prediction.

  6. Residual stresses in continuous graphite fiber Al metal matrix composites

    Science.gov (United States)

    Park, Hun Sub; Zong, Gui Sheng; Marcus, Harris L.

    1988-01-01

    The residual stresses in graphite fiber reinforced aluminum (Gr/Al) composites with various thermal histories are measured using X-ray diffraction (XRD) methods. The XRD stress analysis is based on the determination of lattice strains by precise measurements of the interplanar spacings in different directions of the sample. The sample is a plate consisting of two-ply P 100 Gr/Al 6061 precursor wires and Al 6061 overlayers. Prior to XRD measurement, the 6061 overlayers are electrochemically removed. In order to calibrate the relationship between stress magnitude and lattice spacing shift, samples of Al 6061 are loaded at varying stress levels in a three-point bend fixture, while the stresses are simultaneously determined by XRD and surface-attached strain gages. The stresses determined by XRD closely match those determined by the strain gages. Using these calibrations, the longitudinal residual stresses of P 100 Gr/Al 6061 composites are measured for various heat treatments, and the results are presented.

  7. Determination of Mechanical Properties of Micromembranes with Compressive Residual Stress

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel model of a load-deflection method to determine the mechanical properties of micromembranes with compressive residual stress is described. Since thin film structures are frequently used in micro devices, characterisation of mechanical properties of thin films is desired by the design and fabrication of micromachines. In this paper, the mechanical properties of thin micromembranes under compressive stress are characterised, which are fabricated by bulk micromachining. The relation between the center deflection and the load pressure on a square membrane is deduced by modelling the membrane as an elastic plate having large deflection with clamped boundaries. According to the model, whether the membrane has initial deflection or not has no effect on the measurement result. The Young's modulus and residual stress are simultaneously determined. The mechanical properties of siliconoxide, silicon nitride membranes and composite membranes of polysilicon with silicon nitride are measured.

  8. Effect of welding techniques on microstructure and mechanical properties of aluminium-lithium alloy welds

    Energy Technology Data Exchange (ETDEWEB)

    Madhusudhan Reddy, G.; Gokhale, A.A.; Saxena, V.K. [Defence Metallurgical Research Lab., Hyderabad (India); Prasad Rao, K.

    2000-07-01

    The tensile properties and fatigue crack growth behaviour of sheets of an Al-1.9Li-1.8Cu-1.0 Mg-0.1Zr alloy welded under different conditions were evaluated. The basic welding technique was constant current (CC) gas tungsten arc (GTA) welding. Two modifications viz. pulsed current (PC) and magnetic arc oscillation (AO) were introduced to study effects on microstructure and properties. Both PC and AO resulted in microstructural refinement in the fusion zone. The tensile residual stresses present in CC welds reduced when either PC or AO welding was used. The tensile strength and ductility increased, and fatigue crack growth rates lowered when PC or AO conditions replaced CC welding. (orig.)

  9. Microstructure, local mechanical properties and stress corrosion cracking susceptibility of an SA508-52M-316LN safe-end dissimilar metal weld joint by GTAW

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Hongliang; Zhu, Ruolin [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049 (China); Zhang, Zhiming [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Jianqiu, E-mail: wangjianqiu@imr.ac.cn [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Han, En.-Hou.; Ke, Wei [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Su, Mingxing [Shanghai Research Center for Weld and Detection Engineering Technique of Nuclear Equipment, Shanghai 201306 (China)

    2016-07-04

    The microstructure, local mechanical properties and local stress corrosion cracking susceptibility of an SA508-52M-316LN domestic dissimilar metal welded safe-end joint used for AP1000 nuclear power plant prepared by automatic gas tungsten arc welding was studied in this work by optical microscopy, scanning electron microscopy (with electron back scattering diffraction and an energy dispersive X-ray spectroscopy system), micro-hardness testing, local mechanical tensile testing and local slow strain rate tests. The micro-hardness, local mechanical properties and stress corrosion cracking susceptibility across this dissimilar metal weld joint vary because of the complex microstructure across the fusion area and the dramatic chemical composition change across the fusion lines. Briefly, Type I boundaries and Type II boundaries exist in 52Mb near the SA508-52Mb interface, a microstructure transition was found in SA508 heat affected zone, the residual strain and grain boundary character distribution changes as a function of the distance from the fusion boundary in 316LN heat affected zone, micro-hardness distribution and local mechanical properties along the DMWJ are heterogeneous, and 52Mw-316LN interface has the highest SCC susceptibility in this DMWJ while 316LN base metal has the lowest one.

  10. Surface preparation for XRD residual stress measurements; Preparacao de superficie para medicao de tensoes residuais em soldagem por DRX

    Energy Technology Data Exchange (ETDEWEB)

    Mishchenko, Andrii; Oliveira, Bruno Jose de; Scotti, Americo, E-mail: asmwelder@gmail.com, E-mail: brunojoliveira7@gmail.com, E-mail: ascotti@mecanica.ufu.br [Universidade Federal de Uberlandia (UFU), MG (Brazil)

    2016-10-15

    A characteristic feature of the X Ray Diffraction (XRD) method for stress determination is that measurements occur at a thin surface layer. Steel sheets come with surfaces modified by lamination, cleaning (sandblasting, grinding) and even corrosion, which induce residual stresses or roughness inherent to the material. Therefore, surface preparation prior to the residual stress measurement is essential, although no standard procedure seems to be available. A general recommendation is to remove a thin layer so that only residual stresses related to the welding process will be measured. In this study, the use of portable electrolytic equipment was evaluated for mechanized surface material removal. Chemical compositions of electrolytic solutions and the influence of current on the removed material, removal time and temperature during the process were studied. As a result, a suitable chemical solution for electro etching of low carbon steel was developed and a set of “soft” parameters that allowed the removal of about 300 um in a reasonable time was found. Higher currents reduce the removal time, yet increasing the consumption of the solution and plate temperature (which could adversely alter the microstructure or generate thermal stresses). Furthermore, the influence of these parameters on the operability of the process was demonstrated. (author)

  11. Thermal Stress and Residual Stress Control of Thermally Sprayed 80Ni20Cr Coating

    OpenAIRE

    Ishida, Tsuyoshi; Setoguchi, Katsuya; Hiraki, Kunihiro

    1999-01-01

    In order to find an effective method to control the residual coating stress after thermal spraying, an analysis and experiment were carried out on a cylindrical member of 80Ni20Cr/SUS304. Temperature measurements during the processes of thermal spraying, heating and cold thermal shock were carried out. Using these measured results, thermal stress analyses were perfomed by the finite element method(FEM) and a proposed simplified method for estimating the coating stress. Thermal stress of the c...

  12. Quantifying residual stress in nanoscale thin polymer films via surface wrinkling.

    Science.gov (United States)

    Chung, Jun Young; Chastek, Thomas Q; Fasolka, Michael J; Ro, Hyun Wook; Stafford, Christopher M

    2009-04-28

    Residual stress, a pervasive consequence of solid materials processing, is stress that remains in a material after external forces have been removed. In polymeric materials, residual stress results from processes, such as film formation, that force and then trap polymer chains into nonequilibrium stressed conformations. In solvent-cast films, which are central to a wide range of technologies, residual stress can cause detrimental effects, including microscopic defect formation and macroscopic dimensional changes. Since residual stress is difficult to measure accurately, particularly in nanoscale thin polymer films, it remains a challenge to understand and control. We present here a quantitative method of assessing residual stress in polymer thin films by monitoring the onset of strain-induced wrinkling instabilities. Using this approach, we show that thin (>100 nm) polystyrene films prepared via spin-coating possess residual stresses of approximately 30 MPa, close to the crazing and yield stress. In contrast to conventional stress measurement techniques such as wafer curvature, our technique has the resolution to measure residual stress in films as thin as 25 nm. Furthermore, we measure the dissipation of residual stress through two relaxation mechanisms: thermal annealing and plasticizer addition. In quantifying the amount of residual stress in these films, we find that the residual stress gradually decreases with increasing annealing time and plasticizer amounts. Our robust and simple route to measure residual stress adds a key component to the understanding of polymer thin film behavior and will enable identification of more effective processing routes that mitigate the detrimental effects of residual stress.

  13. Relating Residual Stress and Substructural Evolution During Tensile Deformation of an Aluminum-Manganese Alloy

    Science.gov (United States)

    Lodh, Arijit; Tak, Tawqeer Nasir; Prakash, Aditya; Guruprasad, P. J.; Hutchinson, Christopher; Samajdar, Indradev

    2017-08-01

    Interrupted tensile tests were coupled with ex situ measurements of residual stress and microtexture. The residual stress quantification involved measurements of six independent Laue spots and conversion of the interplanar spacings to the residual stress tensor. A clear orientation-dependent residual stress evolution emerged from the experiments and the numerical simulations. For the orientations undergoing negligible changes in ρ GND (density of geometrically necessary dislocation), the residual stress developments appeared to be governed by the elastic stiffness of the grain clusters. For the others, the evolution of the residual stress and ρ GND exhibited a clear orientation-dependent scaling.

  14. Residual Stress Measurements After Proof and Flight: ETP-0403

    Science.gov (United States)

    Webster, Ronald L..

    1997-01-01

    The intent of this testing was to evaluate the residual stresses that occur in and around the attachment details of a case stiffener segment that has been subjected to flight/recovery followed by proof loading. Not measured in this test were stresses relieved at joint disassembly due to out-of-round and interference effects, and those released by cutting the specimens out of the case segment. The test article was lightweight case stiffener segment 1U50715, S/N L023 which was flown in the forward stiffener position on flight SRM 14A and in the aft position on flight SRM24A. Both of these flights were flown with the 3 stiffener ring configuration. Stiffener L023 had a stiffener ring installed only on the aft stub in its first flight, and it had both rings installed on its second flight. No significant post flight damage was found on either flight. Finally, the segment was used on the DM-8 static test motor in the forward position. No stiffener rings were installed. It had only one proof pressurization prior to assignment to its first use, and it was cleaned and proof tested after each flight. Thus, the segment had seen 3 proof tests, two flight pressurizations, and two low intensity water impacts prior to manufacturing for use on DM-8. On DM-8 it received one static firing pressurization in the horizontal configuration. Residual stresses at the surface and in depth were evaluated by both the x-ray diffraction and neutron beam diffraction methods. The x-ray diffraction evaluations were conducted by Technology for Energy Corporation (TEC) at their facilities in Knoxville, TN. The neutron beam evaluations were done by Atomic Energy of Canada Limited (AECL) at the Chalk River Nuclear Laboratories in Ontario. The results showed general agreement with relatively high compressive residual stresses on the surface and moderate to low subsurface tensile residual stresses.

  15. Numerical aspects for efficient welding computational mechanics

    Directory of Open Access Journals (Sweden)

    Aburuga Tarek Kh.S.

    2014-01-01

    Full Text Available The effect of the residual stresses and strains is one of the most important parameter in the structure integrity assessment. A finite element model is constructed in order to simulate the multi passes mismatched submerged arc welding SAW which used in the welded tensile test specimen. Sequentially coupled thermal mechanical analysis is done by using ABAQUS software for calculating the residual stresses and distortion due to welding. In this work, three main issues were studied in order to reduce the time consuming during welding simulation which is the major problem in the computational welding mechanics (CWM. The first issue is dimensionality of the problem. Both two- and three-dimensional models are constructed for the same analysis type, shell element for two dimension simulation shows good performance comparing with brick element. The conventional method to calculate residual stress is by using implicit scheme that because of the welding and cooling time is relatively high. In this work, the author shows that it could use the explicit scheme with the mass scaling technique, and time consuming during the analysis will be reduced very efficiently. By using this new technique, it will be possible to simulate relatively large three dimensional structures.

  16. 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

  17. New Developed Welding Electrode for Improving the Fatigue Strength of Welded Joints

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new welding electrode, low transformation temperatur e electrode (LTTE), was introduced in this paper. It was described in design principle, mechanics, chemical compositions of their deposited metal and manufacturing methods.It was proved that the best transformation starting temperature from austenite to martensite of the deposited metal of LTTE was at about 191℃ and it was obtained by adding alloying elements such as Cr, Ni, Mn and Mo. The microstructure of the weld metal of the LTTE was low carbon martensite and residual austenite. The compressive residual stress was induced around the weld of the LTTE and the -145 MPa in compression could be obtained in middle of weld metal. The fatigue tests showed that the fatigue strength of the longitudinal welded joints welded with the LTTE at 2×106 cycles was improved by 59% compared with that of the same type of welded joints welded with conventional E5015 and the fatigue life was increased by 47 times at 162 MPa. It is a very valuable method to improve the fatigue performance of welded joints.

  18. Development of a Comprehensive Weld Process Model

    Energy Technology Data Exchange (ETDEWEB)

    Radhakrishnan, B.; Zacharia, T.

    1997-05-01

    This cooperative research and development agreement (CRADA) between Concurrent Technologies Corporation (CTC) and Lockheed Martin Energy Systems (LMES) combines CTC's expertise in the welding area and that of LMES to develop computer models and simulation software for welding processes. This development is of significant impact to the industry, including materials producers and fabricators. The main thrust of the research effort was to develop a comprehensive welding simulation methodology. A substantial amount of work has been done by several researchers to numerically model several welding processes. The primary drawback of most of the existing models is the lack of sound linkages between the mechanistic aspects (e.g., heat transfer, fluid flow, and residual stress) and the metallurgical aspects (e.g., microstructure development and control). A comprehensive numerical model which can be used to elucidate the effect of welding parameters/conditions on the temperature distribution, weld pool shape and size, solidification behavior, and microstructure development, as well as stresses and distortion, does not exist. It was therefore imperative to develop a comprehensive model which would predict all of the above phenomena during welding. The CRADA built upon an already existing three- dimensional (3-D) welding simulation model which was developed by LMES which is capable of predicting weld pool shape and the temperature history in 3-d single-pass welds. However, the model does not account for multipass welds, microstructural evolution, distortion and residual stresses. Additionally, the model requires large resources of computing time, which limits its use for practical applications. To overcome this, CTC and LMES have developed through this CRADA the comprehensive welding simulation model described above. The following technical tasks have been accomplished as part of the CRADA. 1. The LMES welding code has been ported to the Intel Paragon parallel computer at

  19. Effect of Spraying Condition and Material Properties on the Residual Stress in Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    Xiancheng ZHANG; Jianming GONG; Shandong TU

    2004-01-01

    The thermomechanical behavior and the distribution of residual stresses due to thermal spraying of NiCoCrAIY coating were studied by thermomechanical finite dement analysis. The effects of phase transformation due to solidifying process of coating particles, thickness and material properties of coating on the residual stresses were discussed.Results showed that residual stress decreases little with the stress relaxation due to the phase transformation. For the substrates with the same thickness, the residual stress increases with the increase in coating thickness. The state of residual stresses relates to the material properties of coating and substrate closely. The stress-induced failure model of coating is also discussed.

  20. Bioinjection treatment: effects of post-injection residual stress on left ventricular wall stress.

    Science.gov (United States)

    Lee, Lik Chuan; Wall, Samuel T; Genet, Martin; Hinson, Andy; Guccione, Julius M

    2014-09-22

    Injection of biomaterials into diseased myocardium has been associated with decreased myofiber stress, restored left ventricular (LV) geometry and improved LV function. However, its exact mechanism(s) of action remained unclear. In this work, we present the first patient-specific computational model of biomaterial injection that accounts for the possibility of residual strain and stress introduced by this treatment. We show that the presence of residual stress can create more heterogeneous regional myofiber stress and strain fields. Our simulation results show that the treatment generates low stress and stretch areas between injection sites, and high stress and stretch areas between the injections and both the endocardium and epicardium. Globally, these local changes are translated into an increase in average myofiber stress and its standard deviation (from 6.9 ± 4.6 to 11.2 ± 48.8 kPa and 30 ± 15 to 35.1 ± 50.9 kPa at end-diastole and end-systole, respectively). We also show that the myofiber stress field is sensitive to the void-to-size ratio. For a constant void size, the myofiber stress field became less heterogeneous with decreasing injection volume. These results suggest that the residual stress and strain possibly generated by biomaterial injection treatment can have large effects on the regional myocardial stress and strain fields, which may be important in the remodeling process.

  1. Effects of laser heat treatment on the fracture morphologies of X80 pipeline steel welded joints by stress corrosion

    Institute of Scientific and Technical Information of China (English)

    De-jun Kong; Cun-dong Ye

    2014-01-01

    The surfaces of X80 pipeline steel welded joints were processed with a CO2 laser, and the effects of laser heat treatment (LHT) on H2S stress corrosion in the National Association of Corrosion Engineers (NACE) solution were analyzed by a slow strain rate test. The frac-ture morphologies and chemical components of corrosive products before and after LHT were analyzed by scanning electron microscopy and energy-dispersive spectroscopy, respectively, and the mechanism of LHT on stress corrosion cracking was discussed. Results showed that the fracture for welded joints was brittle in its original state, while it was transformed to a ductile fracture after LHT. The tendencies of hydro-gen-induced corrosion were reduced, and the stress corrosion sensitivity index decreased from 35.2%to 25.3%, indicating that the stress corrosion resistance of X80 pipeline steel welded joints has been improved by LHT.

  2. Fatigue Strength and Residual Stress Analysis of Deep Rolled Crankshafts

    Directory of Open Access Journals (Sweden)

    Imran M Quraishi

    2012-12-01

    Full Text Available The endurance life of an engine crankshaft is closely related to its fatigue strength, in addition to other material properties and shape parameters. Deep rolling, moreover, enhances the fatigue limit by applying compressive residual stress within the fillet radius area as a major surface hardening technique. The objective of this paper isto maximize fatigue life of engine through crankshaft design optimization by quantifying fatigue strength for microalloyed steels versus Cr-Mo alloy steel, and to examine the effects of deep rolling load and rolled fillet geometry. Fatigue tests have been made with standard rotary bending test samples from both bar and forged blanks. Rig tests for actual crankshafts have been made to show how the fatigue strength correlates with different sample types. A correlation of stress distribution with bending moment was demonstrated by applying a strain gauging technique on crankshaft specimens. Therefore, an analysis of combined stresses could be made by considering the effect of static residual stress in addition to the applied dynamic bending stress. Optimum conditions for rolling load, fillet geometry and material were identified. Consequently, these results will be adapted to CAE analysis database to enable an optimization of safety factors.

  3. INTERFACE DEVICE FOR NONDESTRUCTIVE TESTING OF RESIDUAL SURFACE STRESSES

    Directory of Open Access Journals (Sweden)

    Gennady A. Perepelkin

    2016-01-01

    Full Text Available The paper considers the organization of connection of a personal computer with a device for nondestructive testing of residual surface stresses. The device works is based on the phenomenon of diffraction of ionizing radiation from the crystal lattice near the surface of the crystallites. Proposed software interface to the organization for each type of user: the device developers, administrators, users. Some aspects of the organization of communication microcontroller to a PC via USB-port

  4. Residual formability of preformed and subsequently welded advanced high strength steels (Reform): Final Report

    OpenAIRE

    Standfuß, Jens; Jahn, Axel; Weber, P; Neges, J.; Wischmann, S.; Höfemann, M.; Sierlinger, R.; Cretteur, L.; Veldt, T. van der; Veit, R.; Trattnig, G.; Pickett, A.; D Aiuto, F.

    2014-01-01

    The research project Reform was situated within the scope of research and technological development of steel and its utilisation. The central point of investigation was the determination of the load capability of preformed and subsequently welded parts made of high-strength steels. In order to cover a wide spectrum of automotive steel applications and with respect to the current development of modern high-strength steels, - two dual phase steels (HCT780X, HCT980X), - one trip steel (HCT690T),...

  5. Fluid-structure-interaction analysis for welded pipes with flow-accelerated corrosion wall thinning

    Energy Technology Data Exchange (ETDEWEB)

    Sun, L.; Ding, Y., E-mail: lan.sun@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2016-06-15

    The flow-accelerated corrosion (FAC) entrance effect results in enhanced wall thinning immediately downstream of a weld if the weld connects an upstream FAC-resistant material with a downstream less resistant material. The weld regions, especially those with local repairs, are susceptible to cracking due to the high residual stresses induced by fabrication. The combined effects of the FAC entrance effect and high stresses at a weld might compromise the structural integrity of the piping and lead to a failure. Weld degradation by FAC entrance effect has been observed at nuclear and fossil power plants. This paper describes an application using fluid-structure-interaction (FSI) modelling to study the combined effects of FAC wall thinning, weld residual stresses, and in-service loads on welded structures. Simplified cases analyzed were based on CANDU outlet feeder conditions. The analysis includes the flow and mass transfer modelling of the FAC entrance effect using computational fluid dynamics (CFD) and nonlinear structural analyses of the welded structures with wall thinning and an assumed weld residual stress and strain distribution. The FSI analyses were performed using ANSYS Workbench, an integrated platform that enables the coupling of CFD and structural analysis solutions. The obtained results show that the combination of FAC, weld residual stresses, in-service loads (including the internal pressure) and (or) extreme loads could cause high stresses and affect the integrity of the welded pipes. The present work demonstrated that the FSI modelling can be used as an effective approach to assess the integrity of welded structures. (author)

  6. Modelling Of Residual Stresses Induced By High Speed Milling Process

    Science.gov (United States)

    Desmaison, Olivier; Mocellin, Katia; Jardin, Nicolas

    2011-05-01

    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® software, is based on data taken from Outeiro & 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&D to those given by numerical simulations is achieved.

  7. Residual stresses determination in textured substrates for plasma sprayed coatings

    Science.gov (United States)

    Capek, J.; Pala, Z.; Kovarik, O.

    2015-04-01

    In this contribution, we have striven to respond to the desire of obtaining the residual stress tensor in the both cold-rolled and hot-rolled substrates designated for deposition of thermal coatings by plasma spraying. Residual stresses play an important role in the coating adhesion to the substrate and, as such, it is a good practice to analyse them. Prior to spraying, the substrate is often being grit blasted. Residual stresses and texture were quantitatively assessed in both virgin and grit blasted sample employing three attitudes. Firstly without taking preferred orientation into account, secondly from measurements of interplanar lattice spacings of planes with high Miller indices using MoKα radiation. And eventually, by calculating anisotropic elastic constants as a weighted average between single-crystal and X-ray elastic constants with weighting being done according to the amount of textured and isotropic material in the irradiated volume. In the ensuing verification analyses, it was established that the latter approach is suitable for materials with either very strong or very weak presence of texture.

  8. 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.

  9. Thermoelastic Stress Analysis: An NDE Tool for the Residual Stress Assessment of Metallic Alloys

    Science.gov (United States)

    Gyekenyesi, Andrew L.; Baaklini, George Y.

    2000-01-01

    During manufacturing, certain propulsion components that will be used in a cyclic fatigue environment are fabricated to contain compressive residual stresses on their surfaces because these stresses inhibit the nucleation of cracks. Overloads and elevated temperature excursions cause the induced residual stresses to dissipate while the component is still in service, lowering its resistance to crack initiation. Research at the NASA Glenn Research Center at Lewis Field has focused on employing the Thermoelastic Stress Analysis technique (TSA, also recognized as SPATE: Stress Pattern Analysis by Thermal Emission) as a tool for monitoring the residual stress state of propulsion components. TSA is based on the fact that materials experience small temperature changes when they are compressed or expanded. When a structure is cyclically loaded (i.e., cyclically compressed and expanded), the resulting surface-temperature profile correlates to the stress state of the structure s surface. The surface-temperature variations resulting from a cyclic load are measured with an infrared camera. Traditionally, the temperature amplitude of a TSA signal has been theoretically defined to be linearly dependent on the cyclic stress amplitude. As a result, the temperature amplitude resulting from an applied cyclic stress was assumed to be independent of the cyclic mean stress.

  10. FEM SIMULATION OF RESIDUAL STRESSES INDUCED BY LASER SHOCK WITH OVERLAPPING LASER SPOTS

    Institute of Scientific and Technical Information of China (English)

    Y.X. Hu; Z.Q. Yao

    2008-01-01

    The finite element method is presented to attain the numerical simulation of the residual stresses field in the material treated by laser shock processing. The distribution of residual stresses generated by a single laser shock with square and round laser spot is predicted and validated by experimental results. With the Finite Element Method (FEM) model, effects of different overlapping rates and impact sequences on the distribution of residual stresses are simulated. The results indicate that: (1) Overlapping laser shock can increase the compressive residual stresses. However, it is not effective on the growth of plastically affected depth; (2) Overlapping rate should be optimized and selected carefully for the large area treatment. Appropriate overlapping rate is beneficial to obtain a homogeneous residual stress field; (3) The impact sequence has a great effect on the residual stress field. It can greatly attenuate the phenomenon of the "residual stress hole" to obtain a homogeneous residual stress field.

  11. Using of abrasive water jet for measurement of residual stress in railway wheels

    OpenAIRE

    Hlaváček, P. (Petr); Brumek, J.; Horsák, L.

    2012-01-01

    The paper provides a general introduction to methods of measurement of residual stresses on railway wheels. Determination of residual stress distribution is necessary for the prediction of wheel service life and possible catastrophic failure. Therefore experimental section is devoted to residual stress measurement using strain gauges according to standard EN 13262 + A1. During measurement, several segments of tested wheel were cut by abrasive water jet to detect changes of residual stresses o...

  12. Evaluation of residual stress relief of aluminum alloy 7050 by using crack compliance method

    Institute of Scientific and Technical Information of China (English)

    王秋成; 柯映林; 邢鸿燕; 翁泽宇; 杨芳儿

    2003-01-01

    High strength aluminum alloys of 7xxx series have unacceptable levels of quenching residual stresses from solution heat treatment. The residual stress not only results in machining distortion and dimensional instability, but also increases the possibility of stress corrosion cracks. Therefore, it is necessary to reduce the residual stress to an acceptable level. The crack compliance method was adopted to study the influences of various stress relief methods on residual stress patterns in 7050 aluminum alloy. The results show that 90% residual stress can be eliminated by the cold stretching(Tx51) method. And a lower level of residual stress can be achieved by the uphill quenching(Tx53) method or the cold compression(Tx52). However, there is a very steep residual stress gradient normal to exterior surfaces.

  13. Mitigation of stress corrosion cracking in pressurized water reactor (PWR) piping systems using the mechanical stress improvement process (MSIP{sup R)} or underwater laser beam welding

    Energy Technology Data Exchange (ETDEWEB)

    Rick, Grendys; Marc, Piccolino; Cunthia, Pezze [Westinghouse Electric Company, LLC, New York (United States); Badlani, Manu [Nu Vision Engineering, New York (United States)

    2009-04-15

    A current issue facing pressurized water reactors (PWRs) is primary water stress corrosion cracking (PWSCC) of bi metallic welds. PWSCC in a PWR requires the presence of a susceptible material, an aggressive environment and a tensile stress of significant magnitude. Reducing the potential for SCC can be accomplished by eliminating any of these three elements. In the U.S., mitigation of susceptible material in the pressurizer nozzle locations has largely been completed via the structural weld overlay (SWOL) process or NuVision Engineering's Mechanical Stress Improvement Process (MSIP{sup R)}, depending on inspectability. The next most susceptible locations in Westinghouse designed power plants are the Reactor Vessel (RV) hot leg nozzle welds. However, a full SWOL Process for RV nozzles is time consuming and has a high likelihood of in process weld repairs. Therefore, Westinghouse provides two distinctive methods to mitigate susceptible material for the RV nozzle locations depending on nozzle access and utility preference. These methods are the MSIP and the Underwater Laser Beam Welding (ULBW) process. MSIP applies a load to the outside diameter of the pipe adjacent to the weld, imposing plastic strains during compression that are not reversed after unloading, thus eliminating the tensile stress component of SCC. Recently, Westinghouse and NuVision successfully applied MSIP on all eight RV nozzles at the Salem Unit 1 power plant. Another option to mitigate SCC in RV nozzles is to place a barrier between the susceptible material and the aggressive environment. The ULBW process applies a weld inlay onto the inside pipe diameter. The deposited weld metal (Alloy 52M) is resistant to PWSCC and acts as a barrier to prevent primary water from contacting the susceptible material. This paper provides information on the approval and acceptance bases for MSIP, its recent application on RV nozzles and an update on ULBW development.

  14. 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.

  15. 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

  16. 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

  17. Effect of transformation on stress releasement of stress concentration area in welding. Part 6. ; Stress releasement by transformation superplasticity. Sohentai ga oryoku shuchubu no oryoku kanwa tokusei ni oyobosu eikyo. 6. ; Hentai chososei ni yoru oryoku kanwa

    Energy Technology Data Exchange (ETDEWEB)

    Murata, H. (Yokogawa Medical System Ltd., Tokyo (Japan)); Kato, N.; Iiyama, T. (Tokyo Inst. of Technology, Tokyo (Japan)); Tamura, H. (Nihon Univ., Tokyo (Japan))

    1993-11-05

    As the various contrivances are being done for raising the strength and reliability of the joints in the usual welding execution, the welding defects out of them are thought that they impair the reliability of the joints, and therefore the efforts not so as to let them occur, and in addition, to secure the safety by screening them through the nondestructive inspection, are being performed. In this report, through the double end constraint thermal cycle tests by using the smooth and notched round bar specimen prepared by the friction pressure welding of 9%Ni steel, which could transform at a low temperature, with SUS 304, and moreover through welding by using the welding rod prepared experimentally of the Fe-Ni-Cr system, which could transform at a low temperature, and furthermore through measuring the thermal contraction stress when the extreme strains have been concentrated in the weld metal parts on the way of cooling off, the fracture character of the weld metal has been investigated. In case of actual welding, even when the extreme stress concentration has been created so excessively as D4316 has started to be fractured on its way of cooling off, no crack has occurred in the welding rod of the low temperature transformation. This is thought because of that the superplasticity phenomena due to the martensite transfomation act effectively on the stress releasement. 12 refs., 14 figs., 2 tabs.

  18. Modeling and fatigue assessment of weld start-end locations based on the effective notch stress approach

    Energy Technology Data Exchange (ETDEWEB)

    Malikoutsakis, M. [Aristotle University of Thessaloniki, Faculty of Mechanical Engineering, Laboratory of Machine Elements Machine Design, 54124 Thessaloniki (Greece); Savaidis, G.

    2011-04-15

    The present paper contains a methodology for modeling and life assessment of fatigue loaded welded components providing distinct weld start and end locations. The proposed methodology follows the IIW recommendation regarding modeling and finite element meshing of weld toe and root by means of an effective notch radius and uses the corresponding Woehler curve (FAT class) to assess the durability. Geometrical singularities and, therewith, numerical discontinuities, can be overcome especially when 3D weld root problems are treated. The fatigue life assessment is performed on the basis of normal stresses acting at the failure-critical weld toe and root locations. Comprehensive experimental database containing stress and fatigue life results derived from motor truck's hypoid rear axles providing complex 3D welds subject to vertical, longitudinal, and torsional loading is used to verify the calculation accuracy of the proposed methodology. The agreement between experimentally determined and calculated fatigue results is satisfactory. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Quantification of residual stress from photonic signatures of fused silica

    Science.gov (United States)

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

    2014-02-01

    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 × 10-12 Pa-1. 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.

  20. Phase composition and residual stresses in thermal barrier coatings

    Science.gov (United States)

    Lozovan, A. A.; Betsofen, S. Ya; Ashmarin, A. A.; Ryabenko, B. V.; Ivanova, S. V.

    2016-07-01

    X-ray study of the phase composition and residual stresses distribution in two-layer APS coatings showed that the ceramic layer consists of t-ZrO2 phase with tetragonal lattice and the metal underlayer γ-solid solution based on nickel. In the transition zone thickness of ∼ 100 pm as the distance from the surface was revealed a gradual transition from t-ZrO2 to γ-solid solution. Increase in the specific volume of the metal underlayer resulting TGO growing leads to the formation of this layer high compressive stresses up to 600 MPa. In this case, the ceramic layer contains tensile stress up to 200 MPa.

  1. Experimental examination of fatigue life of welded joint with stress concentration

    Directory of Open Access Journals (Sweden)

    Miodrag Arsic

    2016-03-01

    Full Text Available This paper presents results of experimental examinations of stress concentration influence to fatigue life of butt welded joints with K-groove, produced from the most frequently used structural steel S355J2+N. One group of experiments comprised examinations carried out on the K-groove specimens with stress concentrators of edged notch type. Specimens with short cracks (limited length of initial crack, defined on the basis of the experience from fracture mechanics by the three points bending examinations, have been examined according to standard for the determination of S-N curve, and aimed to determine fatigue strengths for different lengths of initial crack and Relationship between fatigue strength and crack length. Other group of experiments comprised examinations of specimens with edge notch, prepared in accordance with ASTM E 399 for three points bending, in order to establish regularity between crack growth and range of exerted stress intensity factor aimed to determine resistance of welded joint to initial crack growth, namely fatigue threshold (ΔKth.

  2. Intergranular stress corrosion cracking of welded ferritic stainless steels in high temperature aqueous environments

    Energy Technology Data Exchange (ETDEWEB)

    Fukuzuka, Toshio; Shimogori, Kazutoshi; Fujiwara, Kazuo; Tomari, Haruo (Kobe Steel Ltd. (Japan). Central Research and Development Lab.); Kanda, Masao

    1982-07-01

    In considering the application of ferritic stainless steels to heat exchanger tubing materials for moisture separator-reheaters in LWRs, the effects of environmental conditions (temperature, chloride, dissolved oxygen, pH), thermal history, and steel composition (content of C, N, Cr and Ti) on the Inter-Granular Stress Corrosion Cracking (IGSCC) in high temperature aqueous environments, were studied. The IGSCC was proved to depend on steel composition and thermal history rather than environment. From these results, a steel was designed to prevent IGSCC of the welding HAZ for 18Cr and 13Cr steels.

  3. AZ31B镁合金TIG焊接件应力腐蚀性能研究%Research on the Properties of Stress Corrosion Cracking for Tungsten Inert-Gas Arc Welded AZ31B Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    葛茂忠; 项建云; 张永康

    2013-01-01

    为了研究AZ31B镁合金钨极氩弧焊接件应力腐蚀性能,室温下采用三点加载的方式,在去离子水中对试样进行应力腐蚀试验.利用光学显微镜(OM)观测试样微观结构,利用扫描电镜(SEM)观测应力腐蚀断口,利用X-350A型X射线应力仪和CHI660B型电化学工作站分别测定试样表面残余应力和动电位极化曲线.试验结果表明:采用单面焊双面成型工艺,在45~50 A的焊接电流及合适的焊接速度条件下,焊接2.2 mm厚AZ31B镁合金薄板时,钨极氩弧焊能够获得理想的焊接接头,抗拉强度达到209 MPa;焊接件热影响区表面残余拉应力为60 MPa;同母材相比,焊接件自腐蚀电位减小27 mV,腐蚀电流增大了41.4%,从而增加焊接件腐蚀倾向;AZ31B焊接件在去离子水中浸没192 h后出现应力腐蚀开裂,属于穿晶型脆性断裂,这表明AZ31B镁合金焊接件在去离子水中具有很高的应力腐蚀敏感性.%In order to study the properties of the stress corrosion cracking (SCO for the tungsten inert-gas (TIG) arc welded AZ31B magnesium alloy sheets, the SCC susceptibility of the welded samples was assessed by three points loading method in deionized water at room temperature. The microstructure of specimens and fracture surfaces were analyzed by OM and SEM, respectively. Surface residual stress and potentiodynamic polarization behaviors of the welded samples were examined by using X-ray diffraction technology and a CHI660B electrochemical workstation, respectively. The results show that when TIG arc welding was used to weld AZ31B Mg alloy plates with the thickness of 2. 2 mm by using single-side welding double-side molding process, the ideal welding joints can be obtained at the welding current range from 45 A to 50 A and appropriate welding speed, the ultimate tensile strength of the welded joints is 209 Mpa; The residual tensile stress is 60 Mpa in the surface of heat effected zone of the welded joints; corrosion potential

  4. Microstructural residual stress in particle-filled dental composite.

    Science.gov (United States)

    Prejzek, Ondřej; Spaniel, Miroslav; Mareš, Tomáš

    2015-01-01

    The main goal of this study is to develop a micromechanical model of a particle-filled dental composite focused on the residual stress (RS) field developed during the curing process in its microstructure. A finite element model of a representative volume element of filler and resin was developed, and volumetric shrinkage was simulated during the curing process. Four material models (von Mises plasticity model, Drucker-Prager plasticity model, von Mises plasticity model with stress relaxation and Drucker-Prager plasticity with stress relaxation) of the polymer resin were built to assess the influence of the material model on the resulting internal stress. The relationship between the curing process and the magnitude of the stress components will be described, and an analysis of the post-curing state of the material in particular microstructure locations will be conducted in this study. Obtained RS is comparable to the stresses developed in the material under the external load. The substantial dependence on the choice of material model for resin is to be observed, and the suitability of particular models is discussed.

  5. Dependence of diffuse ultrasonic backscatter on residual stress in 1080 steel.

    Science.gov (United States)

    Du, Hualong; Turner, Joseph A

    2016-04-01

    In this article, the effects of residual stress on the ultrasonic scattering in a quenched steel sample are investigated by calculating the change of spatial variance amplitudes of ultrasonic signals after removing residual stress via annealing. The experimental results show that the average spatial variance amplitude decreases by about 11.89% for a scan area on the quenched surface after removing residual stress. This quantity was used to estimate the residual stress based on the developed stress-dependent backscatter model. In addition, the residual stress on the whole scan area was mapped by calculating the change of the spatial variance amplitude for each subarea after annealing, respectively. Diffuse ultrasonic backscatter signals show a high sensitivity to residual stress such that this technique has potential as a non-destructive method for measuring residual