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Sample records for cast austenitic piping

  1. LOW-FREQUENCY PHASED-ARRAY METHODS FOR CRACK DETECTION IN CAST AUSTENITIC PIPING COMPONENTS

    International Nuclear Information System (INIS)

    Studies at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, are being conducted to evaluate nondestructive examination (NDE) approaches for inspecting coarse-grained, austenitic stainless steel reactor components. The work provides information to the United States Nuclear Regulatory Commission (NRC) on the utility, effectiveness, limitations, and reliability of advanced inspection techniques for application on safety-related components in commercial nuclear power plants. This paper describes results from recent assessments using a low-frequency phased-array methodology for detecting cracks in cast austenitic piping welds. Piping specimens that contain thermal and mechanical fatigue cracks located adjacent to welds were examined. The specimens have surface geometrical conditions and weld features that simulate portions of primary piping systems in many U.S. pressurized water reactors (PWRs). In addition, segments of vintage centrifugally cast piping were examined to assess inherent acoustic noise and scattering due to grain structures and determine consistency of ultrasonic (UT) responses from varied circumferential locations. The phased-array UT methods were applied from the outside surface of the specimens using automated scanning devices and water coupling, and employed a modified instrument operating between 500 kHz and 1.0 MHz. Composite volumetric images of the specimens were generated. Results from laboratory studies for assessing crack detection and sizing effectiveness are discussed, including acoustic parameters observed in centrifugally cast piping base materials

  2. Using Low-Frequency Phased Arrays to Detect Cracks in Cast Austenitic Piping Components

    International Nuclear Information System (INIS)

    As part of a multi-year program funded by the United States Nuclear Regulatory Commission (US NRC) to address NDE reliability of inservice inspection (ISI) programs, recent studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, have focused on assessing novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the US NRC on the utility, effectiveness and reliability of ultrasonic testing (UT) and eddy current testing (ET) inspection techniques as related to the ISI of primary piping components in pressurized water reactors (PWRs). This paper describes progress, recent developments and early results from an assessment of a portion of this work relating to the ultrasonic low frequency phased array inspection technique. Westinghouse Owner's Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks, PNNL samples containing thermal fatigue cracks and several blank vintage specimens having very coarse grains that are representative of early centrifugally cast piping installed in PWRs, are being used for assessing the inspection method. The phased array approach was implemented using an R/D Tech Tomoscan III system operating at 1.0 MHz and 500 kHz, providing composite volumetric images of the samples. Several dual, transmit-receive, custom designed low-frequency arrays are employed in laboratory trials. Results from laboratory studies for assessing detection of thermal and mechanical fatigue cracks in cast stainless steel piping welds are discussed

  3. Low Frequency Phased Array Application for Crack Detection in Cast Austenitic Piping

    International Nuclear Information System (INIS)

    As part of a multi-year program funded by the United States Nuclear Regulatory Commission (US NRC) to address nondestructive examination (NDE) reliability of inservice inspection (ISI) programs, studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, have focused on assessing novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the US NRC on the utility, effectiveness and reliability of ultrasonic testing (UT) as related to the ISI of primary piping components in US commercial nuclear power plants. This paper describes progress, recent developments and results from an assessment of a portion of the work relating to the ultrasonic low frequency phased array inspection technique. Westinghouse Owner's Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks, PNNL samples containing thermal fatigue cracks and several blank vintage specimens having very coarse grains that are representative of early centrifugally cast piping installed in PWRs, were used for assessing the inspection method. The phased array approach was implemented using an R/D Tech Tomoscan III system operating at 1.0 MHz and 500 kHz, providing composite volumetric images of the samples. Several dual, transmit-receive, custom designed low-frequency arrays were employed in laboratory trials. Results from laboratory studies for assessing detection, localization and length sizing effectiveness are discussed.

  4. Improvements in Low-Frequency, Ultrasonic Phased-Array Evaluation for Thick Section Cast Austenitic Stainless Steel Piping Components

    International Nuclear Information System (INIS)

    Research is being conducted for the U.S. Nuclear Regulatory Commission (NRC) at the Pacific Northwest National Laboratory (PNNL) to assess the effectiveness and reliability of advanced nondestructive examination (NDE) methods for the inspection of light water reactor (LWR) components. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in coarse-grained steel components. This particular study focused on the evaluation of custom-designed, low-frequency (500 kHz) phased-array (PA) probes for examining welds in thick-section cast austenitic stainless steel (CASS) piping. In addition, research was conducted to observe ultrasonic sound field propagation effects from known coarse-grained microstructures found in parent CASS material. The study was conducted on a variety of thick-wall, coarse-grained CASS specimens that were previously inspected by an older generation 500-kHz PA-UT probe and acquisition instrument configuration. This comparative study describes the impact of the new PA probe design on flaw detection and sizing in a low signal-to-noise environment. The set of Pressurized Water Reactor Owners Group (PWROG) CASS specimens examined in this study are greater than 50.8-mm (2.0-in.) thick with documented flaws and microstructures. These specimens are on loan to PNNL from the Electric Power Research Institute (EPRI) NDE Center in Charlotte, North Carolina. The flaws contained within these specimens are thermal fatigue cracks (TFC) or mechanical fatigue cracks (MFC) and range from 13% to 42% in through-wall extent. In addition, ultrasonic signal continuity was evaluated on two CASS parent material ring sections by examining the edge-of-pipe response (corner geometry) for regions of signal loss.

  5. Technical Letter Report Assessment of Ultrasonic Phased Array Inspection Method for Welds in Cast Austenitic Stainless Steel Pressurizer Surge Line Piping JCN N6398, Task 1B

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Aaron A.; Cinson, Anthony D.; Crawford, Susan L.; Mathews, Royce; Moran, Traci L.; Anderson, Michael T.

    2009-07-28

    Research is being conducted for the U.S. Nuclear Regulatory Commission (NRC) at the Pacific Northwest National Laboratory (PNNL) to assess the effectiveness and reliability of advanced nondestructive examination (NDE) methods for the inspection of light water reactor components. The scope of this research encompasses primary system pressure boundary materials including cast austenitic stainless steels (CASS); dissimilar metal welds; piping with corrosion-resistant cladding; weld overlays, inlays and onlays; and far-side examinations of austenitic piping welds. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in coarse-grained steel components. In this effort, PNNL supports cooperation with Commissariat à l’Energie Atomique (CEA) to assess reliable inspection of CASS materials. The NRC Project Manager has established a cooperative effort with the Institut de Radioprotection et de Surete Nucleaire (IRSN). CEA, under funding from IRSN, are supporting collaborative efforts with the NRC and PNNL. Regarding its work on the NDE of materials, CEA is providing its modeling software (CIVA) in exchange for PNNL offering expertise and data related to phased-array detection and sizing, acoustic attenuation, and back scattering on CASS materials. This collaboration benefits the NRC because CEA performs research and development on CASS for Électricité de France (EdF). This technical letter report provides a summary of a technical evaluation aimed at assessing the capabilities of phased-array (PA) ultrasonic testing (UT) methods as applied to the inspection of welds in CASS pressurizer (PZR) surge line nuclear reactor piping. A set of thermal fatigue cracks (TFCs) was implanted into three CASS PZR surge-line specimens (pipe-to-elbow welds) that were fabricated using vintage CASS materials formed in the 1970s, and flaw responses from these cracks were used to evaluate detection and sizing

  6. Fabrication and ageing of cast austenitic steels

    International Nuclear Information System (INIS)

    An investigation has been undertaken to determine the magnitude of any reduction in properties which may occur in cast duplex stainless steels and weldments during long term exposure to reactor operating conditions. Test panels were fabricated in CF3 stainless steel by a manual metal arc (MMA) process using 19.9.L (Type 308L) consumables. The mechanical properties and intergranular corrosion resistance of parent material and weldments were measured following accelerated ageing at 3750 and 4000C for up to 10,000 hours. Both the impact energy and J/sub R/ fracture toughness properties of the cast austenitic/ferritic stainless steel were reduced following aging at 4000C for 10,000 hours, whereas austenitic stainless steel MMA weld metals exhibited a reduction in J/sub R/ fracture toughness but no change in impact energy. Even in the unaged state, MMA weld metals were shown to have a much lower resistance to stable crack growth than the parent cast steel, and, following aging, there is a further reduction in the ductile tearing resistance of such weld metals. Therefore, in any assessment of the structural integrity of the reactor coolant pump bowl for a pressurized water reactor (PWR), the weld metal fracture properties during service are likely to be of considerable importance

  7. Austenitic steel piping testing exercises in PISC

    International Nuclear Information System (INIS)

    In this paper capability and reliability studies of NDT procedures for the inspection of wrought and cast stainless steel piping used in nuclear power plants will be presented. The capability study was designed to identify procedures that have the potential to detect and size defects and to discriminate between flawed and unflawed material. The reliability study was undertaken to quantify on real and realistic flaws in-service inspection performance (detection and false call capability) under realistic field conditions. Furthermore parametric studes were performed to complement the capability and reliability studies by evaluating the effect of important material and flaw variables.The specimens used in these studies were cast-to-cast, cast-to-wrought, and wrought-to-wrought pipework welds. The evaluation methods used to quantify the inspection performance were selected to be as comparable as possible to the PISC II methods. These were adapted to allow also the evaluation of the effect of false calls. During the PISC II screening exercise for the cast-to-cast stainless steel round robin test and other piping round robin studies, it was indeed found that false call probabilities were large and could not be ignored in the evaluation of the inspection performance. The matrix of samples has also been designed to allow the implementation of specific statistical analysis procedures for the evaluation of results such as for example the relative operative characteristics analysis. (orig.)

  8. Improvements in 500-kHz Ultrasonic Phased-Array Probe Designs for Evaluation of Thick Section Cast Austenitic Stainless Steel Piping Welds

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Susan L.; Cinson, Anthony D.; Moran, Traci L.; Anderson, Michael T.; Diaz, Aaron A.

    2011-02-01

    PNNL has been studying and performing confirmatory research on the inspection of piping welds in coarse-grained steels for over 30 years. More recent efforts have been the application of low frequency phased array technology to this difficult to inspect material. The evolution of 500 kHz PA probes and the associated electronics and scanning protocol are documented in this report. The basis for the probe comparisons are responses from one mechanical fatigue crack and two thermal fatigue cracks in large-bore cast mockup specimens on loan from the Electric Power Research Institution. One of the most significant improvements was seen in the use of piezo-composite elements in the later two probes instead of the piezo-ceramic material used in the prototype array. This allowed a reduction in system gain of 30 dB and greatly reduced electronic noise. The latest probe had as much as a 5 dB increase in signal to noise, adding to its flaw discrimination capability. The system electronics for the latest probe were fully optimized for a 500 kHz center frequency, however significant improvements were not observed in the center frequency of the flaw responses. With improved scanner capabilities, smaller step sizes were used, allowing both line and raster data improvements to be made with the latest probe. The small step sizes produce high resolution images that improve flaw discrimination and, along with the increased signal-to-noise ratio inherent in the latest probe design, enhanced detection of the upper regions of the flaw make depth sizing more plausible. Finally, the physical sizes of the probes were progressively decreased allowing better access to the area of interest on specimens with weld crowns, and the latest probe was designed with non-integral wedges providing flexibility in focusing on different specimen geometries.

  9. A simplified LBB evaluation procedure for austenitic and ferritic steel piping

    International Nuclear Information System (INIS)

    The NRC previously has approved application of LBB analysis as a means to demonstrate that the probability of pipe rupture was extremely low so that dynamic loads associated with postulated pipe break could be excluded from the design basis (1). The purpose of this work was to: (1) define simplified procedures that can be used by the NRC to compute allowable lengths for circumferential throughwall cracks and assess margin against pipe fracture, and (2) verify the accuracy of the simplified procedures by comparison with available experimental data for piping having circumferential throughwall flaws. The development of the procedures was performed using techniques similar to those employed to develop ASME Code flaw evaluation procedures. The procedures described in this report are applicable to pipe and pipe fittings with: (1) wrought austenitic steel (Ni-Cr-Fe alloy) having a specified minimum yield strength less than 45 ksi, and gas metal-arc, submerged arc and shielded metal-arc austentic welds, and (2) seamless or welded wrought carbon steel having a minimum yield strength not greater than 40 ksi, and associated weld materials. The procedures can be used for cast austenitic steel when adequate information is available to place the cast material toughness into one of the categories identified later in this report for austenitic wrought and weld materials

  10. A simplified LBB evaluation procedure for austenitic and ferritic steel piping

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, R.M.; Wichman, K.R.

    1997-04-01

    The NRC previously has approved application of LBB analysis as a means to demonstrate that the probability of pipe rupture was extremely low so that dynamic loads associated with postulated pipe break could be excluded from the design basis (1). The purpose of this work was to: (1) define simplified procedures that can be used by the NRC to compute allowable lengths for circumferential throughwall cracks and assess margin against pipe fracture, and (2) verify the accuracy of the simplified procedures by comparison with available experimental data for piping having circumferential throughwall flaws. The development of the procedures was performed using techniques similar to those employed to develop ASME Code flaw evaluation procedures. The procedures described in this report are applicable to pipe and pipe fittings with: (1) wrought austenitic steel (Ni-Cr-Fe alloy) having a specified minimum yield strength less than 45 ksi, and gas metal-arc, submerged arc and shielded metal-arc austentic welds, and (2) seamless or welded wrought carbon steel having a minimum yield strength not greater than 40 ksi, and associated weld materials. The procedures can be used for cast austenitic steel when adequate information is available to place the cast material toughness into one of the categories identified later in this report for austenitic wrought and weld materials.

  11. Detection by ultrasonic waves of discontinuities in cast steels and weldings of austenitic stainless steels

    International Nuclear Information System (INIS)

    The study of discontinuities in cast iron and austenitic weldings by means of ultrasound is extremely difficult when materials present rough structures. By virtue of the necessity existing in nuclear power plants and others, of verify to the integrity of cast pieces an austenitic weldings, such a verification is being studying at global level. Materials with a rough grain structure, frequently present in industry, are: bombs to moving fluids, pipe fittings, elbows and austenitic weldings. This problem, traditionally, has been studied varying the frequency in gropers. A new approach will be presented here, based in the use of the high sensibility of the equipment and piezoelectric tablet, as well as the maximum withdrawal of perturbation zone in X-ray tube (Author)

  12. Model of Primary Austenite Dendrite Structure in Hypoeutectic Cast Iron

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The solidification of primary austenite in hypoeutectic gray cast iron was studied by stepped grinding and quantitative metallography. The dendrite structure of primary austenite can be described by three models: typical dendrite crystal model, metamorphic dendrite crystal model and network dendrite crystal model. The dendrite crystals formed according to 3rd model is much more than those formed according to other models in this experiment. The primary austenites are connected each other, and the primary stems of austenite could be regarded as secondary arms and vice versa.

  13. 49 CFR 192.275 - Cast iron pipe.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Cast iron pipe. 192.275 Section 192.275... Cast iron pipe. (a) Each caulked bell and spigot joint in cast iron pipe must be sealed with mechanical leak clamps. (b) Each mechanical joint in cast iron pipe must have a gasket made of a...

  14. Thermodynamic stability of austenitic Ni-Mn-Cu cast iron

    Directory of Open Access Journals (Sweden)

    A. Janus

    2014-07-01

    Full Text Available The performed research was aimed at determining thermodynamic stability of structures of Ni-Mn-Cu cast iron castings. Examined were 35 alloys. The castings were tempered at 900 °C for 2 hours. Two cooling speeds were used: furnace-cooling and water-cooling. In the alloys with the nickel equivalent value less than 20,0 %, partial transition of austenite to martensite took place. The austenite decomposition ratio and the related growth of hardness was higher for smaller nickel equivalent value and was clearly larger in annealed castings than in hardened ones. Obtaining thermodynamically stable structure of castings requires larger than 20,0 % value of the nickel equivalent.

  15. Cast alumina forming austenitic stainless steels

    Science.gov (United States)

    Muralidharan, Govindarajan; Yamamoto, Yukinori; Brady, Michael P

    2013-04-30

    An austenitic stainless steel alloy consisting essentially of, in terms of weight percent ranges 0.15-0.5C; 8-37Ni; 10-25Cr; 2.5-5Al; greater than 0.6, up to 2.5 total of at least one element selected from the group consisting of Nb and Ta; up to 3Mo; up to 3Co; up to 1W; up to 3Cu; up to 15Mn; up to 2Si; up to 0.15B; up to 0.05P; up to 1 total of at least one element selected from the group consisting of Y, La, Ce, Hf, and Zr; alumina, and a stable essentially single phase FCC austenitic matrix microstructure, the austenitic matrix being essentially delta-ferrite free and essentially BCC-phase-free. A method of making austenitic stainless steel alloys is also disclosed.

  16. 76 FR 43981 - Circular Welded Austenitic Stainless Pressure Pipe From the People's Republic of China: Final...

    Science.gov (United States)

    2011-07-22

    ... International Trade Administration Circular Welded Austenitic Stainless Pressure Pipe From the People's Republic... antidumping duty order on circular welded austenitic stainless pressure pipe from the People's Republic of..., 2010. \\1\\ See Circular Welded Austenitic Stainless Pressure Pipe From the People's Republic of...

  17. Evaluation of thermal embrittlement susceptibility in cast austenitic stainless steel using artificial neural network

    International Nuclear Information System (INIS)

    Cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing and valve bodies in light water reactors. These components are subject to thermal aging at the reactor operating temperature. Thermal aging results in spinodal decomposition of the delta-ferrite leading to increased strength and decreased toughness. This study shows that ferrite content can be predicted by use of the artificial neural network. The neural network has trained learning data of chemical components and ferrite contents using backpropagation learning process. The predicted results of the ferrite content using trained neural network are in good agreement with experimental ones

  18. Numerical simulation of centrifugal casting of pipes

    International Nuclear Information System (INIS)

    A numerical simulation model for the horizontal centrifugal pipe casting process was developed with the commercial simulation package Flow3D. It considers - additionally to mass, energy and momentum conservation equations and free surface tracking - the fast radial and slower horizontal movement of the mold. The iron inflow is not steady state but time dependent. Of special importance is the friction between the liquid and the mold in connection with the viscosity and turbulence of the iron. Experiments with the mold at controlled revolution speeds were carried out using a high-speed camera. From these experiments friction coefficients for the description of the interaction between mold and melt were obtained. With the simulation model, the influence of typical process parameters (e.g. melts inflow, mold movement, melt temperature, cooling media) on the wall thickness of the pipes can be studied. The comparison to results of pipes from production shows a good agreement between simulation and reality.

  19. Numerical simulation of centrifugal casting of pipes

    Science.gov (United States)

    Kaschnitz, E.

    2012-07-01

    A numerical simulation model for the horizontal centrifugal pipe casting process was developed with the commercial simulation package Flow3D. It considers - additionally to mass, energy and momentum conservation equations and free surface tracking - the fast radial and slower horizontal movement of the mold. The iron inflow is not steady state but time dependent. Of special importance is the friction between the liquid and the mold in connection with the viscosity and turbulence of the iron. Experiments with the mold at controlled revolution speeds were carried out using a high-speed camera. From these experiments friction coefficients for the description of the interaction between mold and melt were obtained. With the simulation model, the influence of typical process parameters (e.g. melts inflow, mold movement, melt temperature, cooling media) on the wall thickness of the pipes can be studied. The comparison to results of pipes from production shows a good agreement between simulation and reality.

  20. Residual-stresses in austenitic stainless-steel primary coolant pipes and welds of pressurized-water reactors

    International Nuclear Information System (INIS)

    Surface and through thickness residual stress measurements were performed on an aged cast austenitic-ferritic stainless steel pipe and on an orbital TIG weld representative of those of primary coolant pipes in pressurized water reactors. An abrasive-jet hole drilling method and a block removal and layering method were used. Surface stresses and through thickness stress profiles are strongly dependent upon heat treatments, machining and welding operations. In the aged cast stainless steel pipe, stresses ranged between -250 and +175 MPa. On and near the orbital TIG weld, the outside surface of the weld was in tension both in the axial and hoop directions, with maximum values reaching 420 MPa in the weld. On the inside surface, the hoop stresses were compressive, reaching -300 MPa. However, the stresses in the axial direction at the root of the weld were tensile within 4 mm depth from the inside surface, locally reaching 280 MPa. (author)

  1. 75 FR 70908 - Circular Welded Austenitic Stainless Pressure Pipe From the People's Republic of China: Extension...

    Science.gov (United States)

    2010-11-19

    ... International Trade Administration Circular Welded Austenitic Stainless Pressure Pipe From the People's Republic... of the antidumping duty order on circular welded austenitic stainless pressure pipe from the People's... for Revocation in Part, 75 FR 22107 (April 27, 2010). The period of review (``POR'') is September...

  2. Austenite Grain Growth and the Surface Quality of Continuously Cast Steel

    Science.gov (United States)

    Dippenaar, Rian; Bernhard, Christian; Schider, Siegfried; Wieser, Gerhard

    2014-04-01

    Austenite grain growth does not only play an important role in determining the mechanical properties of steel, but certain surface defects encountered in the continuous casting industry have also been attributed to the formation of large austenite grains. Earlier research has seen innovative experimentation, the development of metallographic techniques to determine austenite grain size and the building of mathematical models to simulate the conditions pertaining to austenite grain growth during the continuous casting of steel. Oscillation marks and depressions in the meniscus region of the continuously casting mold lead to retarded cooling of the strand surface, which in turn results in the formation of coarse austenite grains, but little is known about the mechanism and rate of formation of these large austenite grains. Relevant earlier research will be briefly reviewed to put into context our recent in situ observations of the delta-ferrite to austenite phase transition. We have confirmed earlier evidence that very large delta-ferrite grains are formed very quickly in the single-phase region and that these large delta-ferrite grains are transformed to large austenite grains at low cooling rates. At the higher cooling rates relevant to the early stages of the solidification of steel in a continuously cast mold, delta-ferrite transforms to austenite by an apparently massive type of transformation mechanism. Large austenite grains then form very quickly from this massive type of microstructure and on further cooling, austenite transforms to thin ferrite allotriomorphs on austenite grain boundaries, followed by Widmanstätten plate growth, with almost no regard to the cooling rate. This observation is important because it is now well established that the presence of a thin ferrite film on austenite grain boundaries is the main cause of reduction in hot ductility. Moreover, this reduction in ductility is exacerbated by the presence of large austenite grains.

  3. The PISC parametric study on the effect of the texture of cast austenitic stainless steel

    International Nuclear Information System (INIS)

    Within the framework of Action 4 (Austenitic Steel Testing) of PISC III, a parametric study was carried out on a set of centrifugally cast stainless steel samples, representative of the main coolant piping of pressurized water nuclear reactors. The samples are obtained from different manufacturers, and feature various grain textures and dimensions. Artificial and realistic flaws were used to assess the detection and sizing capability of ultrasonic examination techniques. The paper analyzes the data as a function of the metal structure and of the main parameter of the testing techniques, which include TRL contact probes and immersion focusing transducers. Guidelines are deduced as to the selection of inspection techniques, in relation with the metallurgical texture of each specimen. In addition, the influence of the presence of a weld across the wavepath is evaluated, as well as the similarity between the responses obtained from crack-like machined reflectors and mechanical fatigue cracks

  4. Fracture formation in austenitic cast steel during thermal fatigue

    Directory of Open Access Journals (Sweden)

    J. Tuleja

    2008-04-01

    Full Text Available In the paper are presented the results of numerical analyses of carburisation and thermal shock effect on fracture formation in stable austenitic cast steel of Fe–Ni–Cr–C type used in the charge–carrying elements of carburising furnaces. Using the method of finite element method, the distribution of stresses developing in carbides and their surrounding matrix were determined during rapid temperature changes. It was showed that very large tensile stresses developed in the carbides “out–coming” onto the alloy surface, regardless of the volume, type and anisotropy of properties, which could have led to their cracking as early as in the first cycles of heating and rapid cooling.

  5. The Influence of Saturation of Cast Iron Austenite with Carbon on the Ausferrite Transformation

    OpenAIRE

    T. Giętka; T. Szykowny; S. Dymski

    2007-01-01

    Austenitizing during quench hardening of the ductile cast iron influences the content of carbon in austenite depending on the soaking heat. On the other hand, the saturation of austenite impacts its transformation in the ausferritizing process of a metal matrix and forming of microstructure. Ductile cast iron with the ferrite matrix was hardened with isothermal transformation in the range of ausferritizing in temperature tpi = 400 i 300 0C and the range of time τpi = 7,5 �� 240 min. Specimens...

  6. CONTINUOUS HORIZONTAL CASTING OF PIPE BRONZE BILLET

    Directory of Open Access Journals (Sweden)

    E. I. Marukovich

    2015-05-01

    Full Text Available An experimental and calculated thermal analysis of the continuous casting of bronze tube billets is developed. Calculated allowable thermal conditions of drawing for stable casting.

  7. Evaluation of material properties considering thermal embrittlement for accelerated aged CF-8M and CF-8A cast austenitic stainless steel

    International Nuclear Information System (INIS)

    Cast austenitic stainless steel have been widely used for primary coolant piping in light water reactors. This material is subject to thermal embrittlement at reactor operating temperature. CF-8M and CF-8A cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing, and valve bodies in light water reactors. Thermal embrittlement results in spinodal decomposition of delta-ferrite leading to decreased fracture toughness. In this study, the specimens were prepared using an accelerated aging method. The measurement of ferrite content, Charpy impact test and J-R test were performed to verify the predicting equation for aged material properties. In case of above 25% ferrite content, predicted result of J-R curve might be non-conservative

  8. Tearing resistance of aged cast austenitic stainless steels

    International Nuclear Information System (INIS)

    CF8 and CF8M type cast stainless steels containing about 10 to 25 % ferrite are used in the primary piping of light water reactors (PWRs and BWRs). It is now recognized that these materials are embrittled by thermal aging at the operating temperature (between 2900C and 3300C), mainly due to precipitation hardening of the ferrite by α', and other phases. Extensive research programs are under way in several countries to better understand the mechanisms of embrittlement and to determine the mechanical properties of components as a function of aging time and temperature. In earlier studies thermal aging embrittlement was mainly characterized by the evolutions of the tensile and Charpy impact properties. However the evaluation of reactor coolant circuit integrity through mechanical analyses requires the knowledge of fracture toughness properties. The first measurements of the tearing resistance of a CF8M type severely aged material were presented in 1983 by SLAMA, PETREQUIN and MAGER. Other contributions to the knowledge of the fracture toughness of aged materials were published, but were relative to medium or high toughness materials. The objective of this paper is to present the results of tearing resistance measurements made on a large spectrum of severely embrittled materials, which allow to give lower bound properties for aged CF8 and CF8M type cast stainless steels

  9. The Influence of Saturation of Cast Iron Austenite with Carbon on the Ausferrite Transformation

    Directory of Open Access Journals (Sweden)

    T. Giętka

    2007-07-01

    Full Text Available Austenitizing during quench hardening of the ductile cast iron influences the content of carbon in austenite depending on the soaking heat. On the other hand, the saturation of austenite impacts its transformation in the ausferritizing process of a metal matrix and forming of microstructure. Ductile cast iron with the ferrite matrix was hardened with isothermal transformation in the range of ausferritizing in temperature tpi = 400 i 300 0C and the range of time τpi = 7,5 �� 240 min. Specimens were gradually austenitized. They were soaked in the nominal temperature tγ = 950 0C, then precooled to the temperature tγ’ = 850 and 800 0C. Microstructure was investigated, there were also defined the proportion of austenite in the matrix of the cast iron and the content of carbon in it and hardness and impact strength in unnotched specimens. It was stated, that the precooling temperature deciding on the content of carbon in austenite influences kinetics of the ausferritic transformation, the content of carbon in the γ phase and impact strength and, in a less degree, hardness. As a result of gradual austenitizing the cast iron after quench hardening, in some conditions of treatment, reached mechanical properties corresponding, according to the ASTM A 897 standard, with high grades of ADI. Chilling in the range of austenitizing in temperature 850 and 800 0C led to the decrease of carbon in austenite what influenced positively on the matrix microstructure and properties of the ADI. Investigations in this range will be continued.

  10. Investigation on thermally aged cast duplex stainless steel piping

    International Nuclear Information System (INIS)

    In order to evaluate integrity of PWR primary coolant pipes, four-point bending test of cast duplex stainless steel pipe specimen had been conducted for seven years until March 2006. Materials testing of tensile properties and fracture toughness, and elastic-plastic analysis of crack growth of test pipe specimen were also performed. Simplified prediction curves of stress vs. strain and fracture toughness (J kJ/m2) of cast stainless steel were prepared for parameters of ferrite number, thermal aging temperature and period. Four-point bending test of pipe specimen with initial inner crack measured load vs. displacement and crack growth curve and showed fracture behavior. Plastic collapse occurred before thermal aging, and ductile crack growth due to thermal aging and tearing instability followed. Ductile crack growth behavior of thermally aged specimen was tested. Numerical analysis of test pipe specimen was performed to simulate ductile crack growth behavior based on obtained stress vs. strain curve and compared with J (kJ/m2) vs. crack depth (mm) curve in good conformity. Numerical analysis of full size pipe based on validated method of test specimen analysis was performed to establish database of J (kJ/m2) for evaluation of thermally aged cast stainless steel piping (T. Tanaka)

  11. Effects of Cr - Ni 18/9 Austenitic Cast Steel Modification by Mischmetal

    OpenAIRE

    Gajewski, M; J. Kasińska

    2012-01-01

    This paper presents the results of Cr - Ni 18/9 austenitic cast steel modifications by mischmetal. The study was conducted on industrial melts. Cast steel was melted in an electric induction furnace with a capacity of 2000 kg and a basic lining crucible. .The mischmetal was introduced into the ladle during tapping of the cast steel from the furnace. The effectiveness of modification was examined with the carbon content of 0.1% and the presence of δ ferrite in the structure of cast steel stabi...

  12. Microstructures and mechanical properties of cast austenite stainless steels after long-term thermal aging at low temperature

    International Nuclear Information System (INIS)

    Highlights: ► The primary circuit piping materials from Ling Ao Nuclear Power Plant was thermally aged for as long as 20,000 h. ► G-phase precipitation was characterized by HRTEM. ► Hardness in ferrite and austenite, tensile properties and impact behaviors of the long-term aged materials were studied. ► The mechanism of thermal aging embrittlement was proposed. - Abstract: The cast austenite stainless steels were investigate in order to understand the microstructural evolution and mechanical properties in the long-term thermal aging at 400 °C for up to 20,000 h. Spinodal decomposition and G-phase precipitation in ferrite after long-term thermal aging lead to the degradation of mechanical properties. Ferrite hardness increases with aging time, but the austenite hardness does not change. Tensile strength is not strongly affected by aging time, but the plasticity has a significant decrease after long-term aging. Under impact with high strain rate, the ferrite phases deform by the way of deformation twinning. High stress concentration on the phase boundaries cause the phase boundary separating and the austenite’s tearing off

  13. Characteristics of low nickel ferritic-austenitic corrosion resistant cast steel

    Directory of Open Access Journals (Sweden)

    B. Kalandyk

    2014-10-01

    Full Text Available The article presents the results of microscopic examinations of corrosion resistant cast steel with reduced nickel content obtained in a test casting with varying wall thickness. Investigations were carried out in as-cast condition and after heat treatment. Regardless of the casting wall thickness, increasing the manganese and nitrogen content to about 5 % and 2 500 ppm, respectively, yields the material with a two-phase microstructure containing ferrite in an amount of 55,6 ÷ 57,2 % (magnetic method and 52,3 ÷ 55,2 % (analytical method. Based on the results of metallographic examinations, total elimination of the secondary austenite from the microstructure was observed. Microhardness measurements showed average values of 352,3 μHV20 and 267 μHV20 for the chromium ferrite and austenite, respectively.

  14. TDA method application to austenite transformation in nodular cast iron with carbides assessment

    Directory of Open Access Journals (Sweden)

    G. Gumienny

    2011-07-01

    Full Text Available In this paper the possibility of TDA method using to austenite transformation in nodular cast iron with carbides assessment is presented. Studies were conducted on cast iron with about 2% molybdenum and 0,70% to 4,50% nickel. On diagrams, where TDA curves are pre- sented, on time axis a logarithmic scale was applied. It has not been used up to now. It was found, that during cooling and crystallization of cast iron in TDA probe, on the derivative curve there is a slight thermal effect from austenite to upper bainite or martensite transformation. Depending on nickel concentration austeniteupper bainite transformation start temperature changed (Bus, while MS temperature was independent of it. An influence of nickel on eutectic transformation temperature in nodular cast iron with carbides was determined too.

  15. Impact Strength of Austenitic and Ferritic-Austenitic Cr-Ni Stainless Cast Steel in -40 and +20°C Temperature

    Directory of Open Access Journals (Sweden)

    Kalandyk B.

    2014-10-01

    Full Text Available Studies described in this paper relate to common grades of cast corrosion resistant Cr-Ni steel with different matrix. The test materials were subjected to heat treatment, which consisted in the solution annealing at 1060°C followed by cooling in water. The conducted investigations, besides the microstructural characteristics of selected cast steel grades, included the evaluation of hardness, toughness (at a temperature of -40 and +20oC and type of fracture obtained after breaking the specimens on a Charpy impact testing machine. Based on the results of the measured volume fraction of ferrite, it has been found that the content of this phase in cast austenitic steel is 1.9%, while in the two-phase ferritic-austenitic grades it ranges from 50 to 58%. It has been demonstrated that within the scope of conducted studies, the cast steel of an austenitic structure is characterised by higher impact strength than the two-phase ferritic-austenitic (F-A grade. The changing appearance of the fractures of the specimens reflected the impact strength values obtained in the tested materials. Fractures of the cast austenitic Cr-Ni steel obtained in these studies were of a ductile character, while fractures of the cast ferritic-austenitic grade were mostly of a mixed character with the predominance of brittle phase and well visible cleavage planes.

  16. Damage mechanism of piping welded joints made from austenitic Steel for the type RBMK reactor

    International Nuclear Information System (INIS)

    In the process of operation of RBMK reactors the damages were taking place on welded piping, produced from austenitic stainless steel of the type 08X18H10T. The inspection of damaged sections in piping has shown that in most cases crack-like defects are of corrosion and mechanical character. The paper considers in details the reasons of damages appearance and their development for this type of welded joints of downcomers 325xl6 mm, which were fabricated from austenitic stainless steel using TlG and MAW welding methods. (author)

  17. Progress in EPRI-programs on the inspection of cast austenitic stainless steel

    International Nuclear Information System (INIS)

    This document presents the progress in EPRI programs on in-service inspection of Cast austenitic Stainless Steel (CSS). The CSS examination strategy is presented, together with results concerning thermal fatigue cracks and mechanical fatigue cracks. A statistical analysis method is provided, in order to estimate the crack detectability and the false call (a non-crack called crack). (TEC)

  18. The PISC parametric study on the effect of cast austenitic steel texture on the capability of ultrasonic examination

    International Nuclear Information System (INIS)

    Within the framework of Action 4 (Austenitic Steel Testing) of PISC III (Programme for the Inspection of Steel Components), a parametric study was carried out on a set of centrifugally cast stainless steel samples, representative of the main coolant piping of pressurized water nuclear reactors. The samples are obtained from different manufacturers, and feature various grain textures and dimensions. Artificial and realistic flaws were used to assess the detection and sizing capability of ultrasonic examination techniques. The paper analyzes the data as a function of the metal structure and of the main parameters of the testing techniques, which include TRL contact probes and immersion focusing transducers. Guidelines are deduced as to the selection of inspection techniques, in relation with the metallurgical texture of each specimen. In addition, the influence of the presence of a weld across the wave path is evaluated, as well as the similarity between the responses obtained from crack-like machined reflectors and mechanical fatigue cracks

  19. TDA method application to austenite transformation in nodular cast iron with carbides assessment

    OpenAIRE

    G. Gumienny

    2011-01-01

    In this paper the possibility of TDA method using to austenite transformation in nodular cast iron with carbides assessment is presented. Studies were conducted on cast iron with about 2% molybdenum and 0,70% to 4,50% nickel. On diagrams, where TDA curves are pre- sented, on time axis a logarithmic scale was applied. It has not been used up to now. It was found, that during cooling and crystallization of cast iron in TDA probe, on the derivative curve there is a slight thermal effect from aus...

  20. Fatigue crack growth rate studies on pipes and pipe welds made of austenitic stainless steel and carbon steel

    International Nuclear Information System (INIS)

    The objective of the present study is to understand the fatigue crack growth behavior in austenitic stainless steel and carbon steel pipes and pipe welds by carrying out analysis/predictions and experiments. The Paris law has been used for the prediction of fatigue crack growth life. To carry out the analysis, Paris constants have been determined for pipe (base) and pipe weld materials by using Compact Tension (CT)/Three Point Bend (TPB) specimens machined from the actual pipe/pipe weld. Analyses have been carried out to predict the fatigue crack growth life of pipes/pipe welds having part through cracks on the outer surface. In the analyses, Stress Intensity Factors (K) have been evaluated through two different schemes. The first scheme considers the 'K' evaluations at two points of the crack front i.e. maximum crack depth and crack tip at the outer surface. The second scheme accounts for the area averaged root mean square stress intensity factor (KRMS) at deepest and surface points. In order to validate the analytical procedure/results, experiments have been carried out on full scale pipe and pipe welds with part through circumferential crack. Fatigue crack growth life evaluated using both schemes have been compared with experimental results. Use of stress intensity factor (KRMS) evaluated using second scheme gives better fatigue crack growth life prediction compared to that of first scheme. (author)

  1. Stress corrosion cracking susceptibility of various austenitic stainless steel pipe welds in high temperature oxygenated water

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) susceptibility of various austenitic stainless steel pipe welds has been studied by means of constant load tensile tests and pipe tests in 2880C water containing 26 ppm dissolved oxygen. The results obtained are summarized as follows: (1) SCC susceptibility of SUS 304 pipe welds is comparatively low under the condition of as-welded. It becomes, however, high remarkably by grinder operation and/or low temperature sensitization heat treatment. The distribution of time of failure on SUS 304 pipe welds can be expressed as a log-normal or Weibull distribution. (2) SUS 304L, 304NG, 316NG, and 347 stainless steel pipe welds have a good SCC resistance and sensitization resistance. Furthermore, the life estimation on alternate pipe welds was conducted statistically. (author)

  2. Evaluation of residual stress distribution in austenitic stainless steel pipe butt-welded joint

    International Nuclear Information System (INIS)

    This paper reports measured and estimated results of residual stress distributions of butt-welded austenitic stainless steel pipe in order to improve estimation accuracy of welding residual stress. Neutron diffraction and strain gauge method were employed for the measurement of the welding residual stress and its detailed distributions on inner and outer surface of the pipe as well as the distributions within the pipe wall were obtained. Finite element method was employed for the estimation. Transient and residual stresses in 3D butt-welded joint model were computed by employing Iterative Substructure Method and also commercial FEM code ABAQUS for a reference. The measured and estimated distributions presented typical characteristic of straight butt-welded pipe which had decreasing trend along the axial direction and bending type distributions through wall of the pipe. Both results were compared and the accuracy of measurement and estimation was discussed. (author)

  3. Effect of aging on mechanical properties of austenitic stainless steel castings and welds

    International Nuclear Information System (INIS)

    Study of the influence of long time aging on the properties of the cast austenitic steel and associated welds or cladding in the components of the primary loop of nuclear plants: embrittlement by precipitation of α'(chromium rich) in ferrite islands (mostly for castings); precipitation hardens the ferrite wich breaks by cleavage. The impact energy and Isub(IC) value are lowered by this phenomenon. Low cycle fatigue properties and fatigue crack growth rates are not modified by aging. Study of correlation between KCU impact toughness at the end of the life of a component, chemical composition and ferrite content

  4. Structure and properties of metal of commercial steam pipes produced by centrifugal casting

    International Nuclear Information System (INIS)

    Structure and properties of metal of large diameter pipes produced by centrifugal casting of 15Kh1M1FL steel are investigated. It is shown that the structure of centrifugally cast pipe metal is much more in homogeneous than that of hot-rolled pipes

  5. Fatigue crack growth in austenitic stainless steel piping

    International Nuclear Information System (INIS)

    The study presented in this paper is being carried out with a view to substantiating the calculations of the fatigue crack growth in pipes made of 316 L stainless steel. The results obtained may be applied to P.W.R. primary piping. It is divided into two parts. First, fatigue tests (cyclic pressure) are carried out under hot and cold conditions with straight pipes machined with notches of various dimensions. The crack propagation and the fatigue crack growth rate are measured here. Second, calculations are made in order to interpret experimental results. From elastic calculations the stress intensity factor is assessed to predict the crack growth rate. The results obtained until now and presented in this paper relate to longitudinal notches

  6. Effects of Cr - Ni 18/9 Austenitic Cast Steel Modification by Mischmetal

    Directory of Open Access Journals (Sweden)

    M. Gajewski

    2012-12-01

    Full Text Available This paper presents the results of Cr - Ni 18/9 austenitic cast steel modifications by mischmetal. The study was conducted on industrial melts. Cast steel was melted in an electric induction furnace with a capacity of 2000 kg and a basic lining crucible. .The mischmetal was introduced into the ladle during tapping of the cast steel from the furnace. The effectiveness of modification was examined with the carbon content of 0.1% and the presence of δ ferrite in the structure of cast steel stabilized with titanium. The changes in the structure of cast steel and their effect on mechanical properties and intergranular corrosion were studied. It was found that rare earth metals decrease the sulfurcontent in cast steel and above all, they cause a distinct change in morphology of the δ ferrite and non-metallic inclusions. These changes have improved mechanical properties. R02, Rm, and A5 and toughness increased significantly. There was a great increase of the resistance to intergranular corrosion in the Huey test. The study confirmed the high efficiency of cast steel modification by mischmetal in industrial environments. The final effect of modification depends on the form and manner of placing mischmetal into the liquid metal and the melting technology, ie the degree of deoxidation and desulfurization of the metal in the furnace.

  7. Mechanized ultrasonic inspection of austenitic pipe systems; Mechanisierte Ultraschallpruefung von austenitischen Rohrleitungen

    Energy Technology Data Exchange (ETDEWEB)

    Dressler, K.; Luecking, J.; Medenbach, S. [ABB ZAQ GmbH, Essen (Germany)

    1999-08-01

    The contribution explains the system of standard testing methods elaborated by ABB ZAQ GmbH for inspection of austenitic plant components. The inspection tasks explained in greater detail are basic materials testing (straight pipes, bends, and pipe specials), and inspection of welds and dissimilar welds. The techniques discussed in detail are those for detection and sizing of defects. (orig./CB) [Deutsch] Das Ziel dieses Beitrages ist die Vorstellung der von der ABB ZAQ GmbH eingesetzten Standardprueftechniken fuer die Pruefung austenitischer Anlagenkomponenten. Im einzelnen wird die Grundwerkstoffpruefung (Rohre, Boegen, Formstuecke), die Schweissnahtpruefung und die Mischnahtpruefung angesprochen. Es werden dabei die Techniken fuer `Detection` und `Sizing` differenziert betrachtet und erlaeutert. (orig.)

  8. Ultrasonic flaw detection of austenitic stainless steel longitudinally welded pipe and tubing

    International Nuclear Information System (INIS)

    Recently there has been the trend that the welded austenitic stainless steel pipe and tubing are used in the nuclear industry in place of the seamless pipe and tubing. For most of the nuclear components, the pipe and tubing must be examined with ultrasonic method by the demands of ASME SA-655. But the ultrasonic flaw detection of the austenitic welds is generally difficult because of scattering and deflection of the acoustic beam due to the coarse grained and elastically anisotropic preferred oriented structure of dendrite. For the thinner welds of pipe and tubing, the attenuation and deflection of the beam do not make the serious problems, however, the deterioration of the signal-to-noise ratio by the coherent structural noise from the welds may still disturb the flaw detection. The longitudinal wave can be employed to suppress the structural noise. This depends upon its longer wave length. In the automatic examination of the pipe and tubing, however, the customary shear wave angle beam technique must be applied to use the skipped beam

  9. Effect of electromagnetic stirring on solidification structure of austenitic stainless steel in horizontal continuous casting

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An investigation on the influence of low frequency rotary electromagnetic stirring on solidification structure of austenitic stainless steel in horizontal continuous casting was experimentally conducted and carried out on an industrial trial basis. The results show that application of appropriate electromagnetic stirring parameters can obviously improve the macrostructure of austenitic stainless steel, in which both columnar and equiaxed grains can be greatly refined and shrinkage porosity or cavity zone along centerline can be remarkably decreased due to eliminating intracrystalline and enlarging equiaxed grains zone. The industrial trials verify that the electromagnetic stirring intensity of austenitic stainless steel should be higher than that of plain carbon steel. Electromagnetic stirring has somewhat affected the macrostructure of austenitic stainless steel even if the magnetic flux density of the electromagnetic stirring reaches 90 mT (amplitude reaches 141 mT ) in average at frequency f=3-4Hz, which provides a reference for the optimization of design and process parameters when applying the rotary electromagnetic stirrer

  10. Effect of heavy ion irradiation on microstructural evolution in CF8 cast austenitic stainless steel

    Science.gov (United States)

    Chen, Wei-Ying; Li, Meimei; Kirk, Marquis A.; Baldo, Peter M.; Lian, Tiangan

    2016-04-01

    The microstructural evolution in ferrite and austenitic in cast austenitic stainless steel (CASS) CF8, as received or thermally aged at 400 °C for 10,000 h, was followed under TEM with in situ irradiation of 1 MeV Kr ions at 300 and 350 °C to a fluence of 1.9 × 1015 ions/cm2 (∼3 dpa) at the IVEM-Tandem Facility. For the unaged CF8, the irradiation-induced dislocation loops appeared at a much lower dose in the austenite than in the ferrite. At the end dose, the austenite formed a well-developed dislocation network microstructure, while the ferrite exhibited an extended dislocation structure as line segments. Compared to the unaged CF8, the aged specimen appeared to have lower rate of damage accumulation. The rate of microstructural evolution under irradiation in the ferrite was significantly lower in the aged specimen than in the unaged. This difference is attributed to the different initial microstructures in the unaged and aged specimens, which implies that thermal aging and irradiation are not independent but interconnected damage processes.

  11. Effect of electromagnetic stirring on solidification structure of austenitic stainless steel in horizontal continuous casting

    Directory of Open Access Journals (Sweden)

    ZHOU Shu-cai

    2007-08-01

    Full Text Available An investigation on the influence of low frequency rotary electromagnetic stirring on solidification structure of austenitic stainless steel in horizontal continuous casting was experimentally conducted and carried out on an industrial trial basis. The results show that application of appropriate electromagnetic stirring parameters can obviously improve the macrostructure of austenitic stainless steel, in which both columnar and equiaxed grains can be greatly refined and shrinkage porosity or cavity zone along centerline can be remarkably decreased due to eliminating intracrystalline and enlarging equiaxed grains zone. The industrial trials verify that the electromagnetic stirring intensity of austenitic stainless steel should be higher than that of plain carbon steel. Electromagnetic stirring has somewhat affected the macrostructure of austenitic stainless steel even if the magnetic flux density of the electromagnetic stirring reaches 90 mT (amplitude reaches 141 mT in average at frequency f=3-4Hz, which provides a reference for the optimization of design and process parameters when applying the rotary electromagnetic stirrer.

  12. 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

  13. Eddy current testing of longitudinal welds in austenitic steel pipes

    International Nuclear Information System (INIS)

    The existing steel-iron test sheet 1914 'Nondestructive Testing of Fusion Welded Joints in Tubes of Stainless Steels' (SEP 1914) had to be revised. The physical correlation between test frequency, phase position, amplitude and defect size for different pipe dimensions were pointed out and discussed on the basis of numerous measurement series. The influence of coil-specific parameters, filtration and electromagnetic magnetization on the eddy current signal were clarified. Additionally, the transferability of the amplitude and phase behaviour of simulated defects on naturally occurring defects was investigated in order to guarantee that the determined test parameters for the revision of existing test regulations are practice-oriented. As the most important result, it is stated that the definition of the test sensitivity in the steel-iron test sheet 1914 is too insensitive for a great number of pipe dimensions. Therefore, the existing steel-iron test sheet 1914 was revised with regard to the definition of the test sensitivity on the basis of the required detection sensitivity of a 20% internal groove. (orig./HP)

  14. Crack resistance of austenitic pipes with circumferential through-wall cracks

    International Nuclear Information System (INIS)

    For monotonously increasing load the correct evaluation of the crack resistance properties of a structure is essential for safety analyses. Considerable attention has been given to the through-wall case, since this is generally believed to be the controlling case with regard to complete pipe failure. The maximum load conditions for circumferential crack growth in pipes under displacement-controlled loadings has been determined. The need for crack resistance curves, measured on circumferentially through-wall cracked straight pipes of austenitic stainless steel 316L under bending, is emphasized by the limitation in the data range on small specimens and by the differences in the procedures. To answer open questions and to improve calculational methods a joint fracture mechanics program is being performed by Electricite de France, Novatome and Siemens-Interatom. The working program contains experimental and theoretical investigations on the applicability of small-specimen data to real structures. 10 refs., 10 figs., 4 tabs

  15. Precipitation kinetics in austenitic 18Cr-30Ni-Nb cast steel

    OpenAIRE

    M. Garbiak; R. Chylińska

    2008-01-01

    The study presents the results of investigations on the precipitation kinetics in austenitic 18%Cr-30%Ni cast steel stabilised with an addition of 1.84 wt% niobium. Phase analysis of isolates extracted from the alloy subjected to annealing within the temperature range of 600–1000oC during 10–1000 h was made. The phase constitution of the isolates mainly comprised niobium carbides of the NbC type and complex chromium carbides of the Cr23C6 type. In specimens annealed within the temperature ran...

  16. Reliability examination of the radiography of austenitic pipe welds

    International Nuclear Information System (INIS)

    The radiographic examination of pipe welds with stress corrosion cracks is a sophisticated testing task. Enhanced reliability is achieved primarily through better seam preparation, welding technique, and post-welding treatment. The statistical methods ROC and POD are very suitable for quantitative measurement of the reliability of NDE, with POD requiring a broader statistical basis. Digital image evaluation requires object-related filtering (longitudinal cracks) or profile generation in order to represent the information describing the crack as an optical optimization. Training and on-screen training is required, and testing experts ought to have good experience with defect types possible. Experienced evaluators will be able to detect with high reliability cracks located half through wall. (orig./MM)

  17. 77 FR 17119 - Pipeline Safety: Cast Iron Pipe (Supplementary Advisory Bulletin)

    Science.gov (United States)

    2012-03-23

    ... Pipeline and Hazardous Materials Safety Administration Pipeline Safety: Cast Iron Pipe (Supplementary...; October 11, 1991 and ALN-92-02; June 26, 1992) covering the continued use of cast iron pipe in natural gas... INFORMATION CONTACT: Jeff Gilliam, Director, Engineering and Research, 202-366-0568 or by email at...

  18. Ultrasonic testing of austenitic and austenitic-ferritic welds made possible by NDT-based optimization of welding techniques, illustrated for some circumferential pipe welds at NPP components, and their qualification

    International Nuclear Information System (INIS)

    The paper summarizes practical results of the making and testing of austenitic and austenitic-ferritic welds in compliance with the KTA codes. The subsequent evaluation is based on mechanized ultrasonic testing for longitudinal flaws in pipe welds made by narrow-gap TIG welding. It is shown that NDT of austenitic as well as austenitic-ferritic root welds produced after optimization of welding techniques can be done with shear wave transducers, and yields satisfactory results. (orig./CB)

  19. Research of estimation method of thermal aging embrittlement on cast austenitic stainless steel

    International Nuclear Information System (INIS)

    Thermal aging embrittlement of cast austenitic stainless steel components from the decommissioned Advanced Thermal prototype Reactor (ATR) Fugen power station has been characterized. Cast stainless steel materials were obtained from recirculation pump casing. The actual time at temperature for the materials was 138,000 h at 275°C. The Fugen serviced material show modest decrease in Charpy-impact properties and a small increase in micro-Vickers hardness in ferrite phase because of thermal aging at relatively low service temperatures. The fracture toughness prediction method (H3T model) predicts slightly lower values for Charpy-impact energy obtained from the Fugen material. The results from microstructural analysis suggest that the prediction method have the potential to provide higher accuracy by considering activation energy for embrittlement at low service temperatures. (author)

  20. NDE Assessments of Cast Stainless Steel Reactor Piping Components

    International Nuclear Information System (INIS)

    Studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, have focused on developing and evaluating the effectiveness and reliability of novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the utility, effectiveness and reliability of ultrasonic testing (UT) and eddy current testing (ET) inspection techniques as related to the in-service inspection of primary piping components in pressurized water reactors (PWRs). This paper describes recent developments and results from assessments of three different NDE approaches including an ultrasonic phased array inspection methodology, an eddy current testing technique and a low-frequency ultrasonic inspection methodology coupled with a synthetic aperture focusing technique (SAFT). Westinghouse Owner's Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks located close to the weld roots, were used for assessing the inspection methods. ET studies were conducted on the inner diameter (ID) surface of piping specimens while the ultrasonic inspection methods were performed from the outer diameter (OD) surface of the specimens. The ET technique employed a ZETEC MIZ-27SI Eddy Current instrument and a ZETEC Z0000857-1 cross point spot probe with an operating frequency of 250 kHz. On some samples where noise levels were high, degaussing of the sample resulted in significant improvements. The phased array approach was implemented using an RD Tech Tomoscan III system operating at 1 MHz and composite volumetric images of the samples were generated. The low-frequency ultrasonic method employs a zone-focused, multi-incident angle; inspection protocol (operating at 250-450 kHz) coupled with a synthetic aperture focusing technique (SAFT) for improved signal-to-noise and advanced imaging capabilities

  1. Corrosion resistance of various bio-films deposited on austenitic cast steel casted by lost-wax process and in gypsum mould

    Directory of Open Access Journals (Sweden)

    J. Gawroński

    2010-01-01

    Full Text Available This work is the next of a series concerning the improvement of austenitic cast steel utility predicted for use in implantology for complicated long term implants casted by lost-wax process and in gypsum mould. Austenitic cast steel possess chemical composition of AISI 316L medical steel used for implants. In further part of present work investigated cast steel indicated as AISI 316L medical steel. Below a results of electrochemical corrosion resistance of carbon layer and bi-layer of carbon/HAp deposited on AISI 316L researches are presented. Coatings were manufactured by RF PACVD and PLD methods respectively. Obtained results, unequivocally indicates on the improvement of this type of corrosion resistance by substrate material with as deposited carbon layer. While bi-layer of carbon/HAp are characterized by very low corrosion resistance.

  2. Ultrasonic Characterization of Cast Austenitic Stainless Steel Microstructure: Discrimination between Equiaxed- and Columnar-Grain Material – An Interim Study

    Energy Technology Data Exchange (ETDEWEB)

    Ramuhalli, Pradeep; Good, Morris S.; Diaz, Aaron A.; Anderson, Michael T.; Watson, Bruce E.; Peters, Timothy J.; Dixit, Mukul; Bond, Leonard J.

    2009-10-27

    Ultrasonic nondestructive evaluation (NDE) and inspection of cast austenitic stainless steel (CASS) components used in the nuclear power industry is neither as effective nor reliable as is needed due to detrimental effects upon the interrogating ultrasonic beam and interference from ultrasonic backscatter. The root cause is the coarse-grain microstructure inherent to this class of materials. Some ultrasonic techniques perform better for particular microstructural classifications and this has led to the hypothesis that an ultrasonic inspection can be optimized for a particular microstructural class, if a technique exists to reliably classify the microstructure for feedback to the inspection. This document summarizes scoping experiments of in-situ ultrasonic methods for classification and/or characterization of the material microstructures in CASS components from the outside surface of a pipe. The focus of this study was to evaluate ultrasonic methods and provide an interim report that documents results and technical progress. An initial set of experiments were performed to test the hypothesis that in-service characterization of cast austenitic stainless steel (CASS) is feasible, and that, if reliably performed, such data would provide real-time feedback to optimize in-service inspections in the field. With this objective in mind, measurements for the experiment were restricted to techniques that should be robust if carried forward to eventual field implementation. Two parameters were investigated for their ability to discriminate between different microstructures in CASS components. The first parameter was a time-of-flight ratio of a normal incidence shear wave to that of a normal incidence longitudinal wave (TOFRSL). The ratio removed dependency on component thickness which may not be accurately reported in the field. The second parameter was longitudinal wave attenuation. The selected CASS specimens provided five equiaxed-grain material samples and five columnar

  3. Structure and properties of tubes made of radiation-resistant austenitic steels, produced by centro fugal vacuum casting

    International Nuclear Information System (INIS)

    The perspectives and effectiveness of centrifugal vacuum casting for manufacturing materials for fuel cladding of nuclear reactors were shown. Temperature and deformation conditions have been selected to manufacture tubes from radiation-resistant steels obtained by centrifugal casting in vacuum. Basically, the possibility is established for using the existing equipment and traditional schemes for thin-walled tube production out of austenitic stainless steels alloyed with scandium or gadolinium

  4. Investigation of Residual Stress Distributions of Induction Heating Bended Austenitic Stainless Steel (316 Series) Piping

    International Nuclear Information System (INIS)

    The induction heating bending process, which has been recently applied to nuclear piping, can generate residual stresses due to thermomechanical mechanism during the process. This residual stress is one of the crack driving forces that have important effects on crack initiation and propagation. However, previous studies have focused only on geometric shape variations such as the change in thickness and ovality. Moreover, very few studies are available on the effects of process variables on residual stresses. This study investigated the effects of process variables on the residual stress distributions of induction heating bended austenitic stainless steel (316 series) piping using parametric finite element analysis. The results indicated that the heat generation rate and feed velocity have significant effects on the residual stresses whereas the moment and bending angle have insignificant effects

  5. Comparison between shear wave ultrasonic examination and radiographic examination of some austenitic stainless steel pipe welds

    International Nuclear Information System (INIS)

    This paper compares the results of the ultrasonic and radiographic examinations of five austenitic pipe to pipe welds, which contained different types of intentional weld defects. Both the ultrasonic and radiographic examinations were made under laboratory conditions, and thus the results cannot directly be generalized to workshop examinations. The ultrasonic examination was performed using a conventional shear wave angle beam technique due to the geometric conditions of the welds. Longitudinal wave angle beam probes were not used in this work. Comparison between the results of the ultrasonic and radiographic examinations leads to the conclusion that neither method gives quite satisfactory results. Both methods missed some defects and the correlation between the results of the methods was not very good. In the ultrasonic examination the most difficult problem was the evaluation of the defects. (author)

  6. Survey report on unmanned site welding of austenitic stainless steel pipe and its ultrasonic examination

    International Nuclear Information System (INIS)

    In the field welding of austenitic stainless steel pipings and its non-destructive test in complicated and narrow places, reliable welding method and non-destructive testing method are required, and also, it is desirable to mechanize them (unmanned operation). In this study, the present state of the automatic welding of austenitic stainless steel pipings and ultrasonic flaw detection was investigated through the literatures in Japan and foreign countries. As the result, it was clarified that energetic research has been made recently to mechanize the welding, and though many points are left for future research and development, it is promising. In the ultrasonic flaw detection, many technical problems concerning the detectability of flaws remain at present, but is is expected to become feasible by future systematic research and development. The design of weld joints, the welding method and the remote automatic control of welding operation must be appropriate for guaranteeing the quality of welding, and these points were surveyed. The problems in the ultrasonic flaw detection are the attenuation of ultrasonic waves, the conditions of probes, the mode of wave motion and frequency, and the welding suitable to the ultrasonic flaw detection. (Kako, I.)

  7. The Effects of Austenitizing Conditions on the Microstructure and Wear Resistance of a Centrifugally Cast High-Speed Steel Roll

    Science.gov (United States)

    Kang, Minwoo; Lee, Young-Kook

    2016-07-01

    The influences of austenitizing conditions on the microstructure and wear resistance of a centrifugally cast high-speed steel roll were investigated through thermodynamic calculation, microstructural analysis, and high-temperature wear tests. When the austenitizing temperature was between 1323 K and 1423 K (1050 °C and 1150 °C), coarse eutectic M2C plates were decomposed into a mixture of MC and M6C particles. However, at 1473 K (1200 °C), the M2C plates were first replaced by both new austenite grains and MC particles without M6C particles, and then remaining M2C particles were dissolved during the growth of MC particles. The wear resistance of the HSS roll was improved with increasing austenitizing temperature up to 1473 K (1200 °C) because the coarse eutectic M2C plates, which are vulnerable to crack propagation, changed to disconnected hard M6C and MC particles.

  8. The Effects of Austenitizing Conditions on the Microstructure and Wear Resistance of a Centrifugally Cast High-Speed Steel Roll

    Science.gov (United States)

    Kang, Minwoo; Lee, Young-Kook

    2016-04-01

    The influences of austenitizing conditions on the microstructure and wear resistance of a centrifugally cast high-speed steel roll were investigated through thermodynamic calculation, microstructural analysis, and high-temperature wear tests. When the austenitizing temperature was between 1323 K and 1423 K (1050 °C and 1150 °C), coarse eutectic M2C plates were decomposed into a mixture of MC and M6C particles. However, at 1473 K (1200 °C), the M2C plates were first replaced by both new austenite grains and MC particles without M6C particles, and then remaining M2C particles were dissolved during the growth of MC particles. The wear resistance of the HSS roll was improved with increasing austenitizing temperature up to 1473 K (1200 °C) because the coarse eutectic M2C plates, which are vulnerable to crack propagation, changed to disconnected hard M6C and MC particles.

  9. Technical basis for the extension of ASME Code Case N-494 for assessment of austenitic piping

    International Nuclear Information System (INIS)

    In 1990, the ASME Boiler and Pressure Vessel Code for Nuclear Components approved Code Case N-494 as an alternative procedure for evaluating flaws in light water reactor (LWR) ferritic piping. The approach is an alternate to Appendix H of the ASME Code and allows the user to remove some unnecessary conservatism in the existing procedure by allowing the use of pipe specific material properties. The Code case is an implementation of the methodology of the deformation plasticity failure assessment diagram (DPFAD). The key ingredient in the application of DPFAD is that the material stress-strain curve must be in the format of a simple power law hardening stress-strain curve such as the Ramberg-Osgood (R-O) model. Ferritic materials can be accurately fit by the R-O model and, therefore, it was natural to use the DPFAD methodology for the assessment of LWR ferritic piping. An extension of Code Case N-494 to austenitic piping required a modification of the existing DPFAD methodology. The modified DPFAD approach, coined piecewise failure assessment diagram (PWFAD), extended an approximate engineering approach proposed by Ainsworth in order to consider materials whose stress-strain behavior cannot be fit to the R-O model. The Code Case N-494 approach was revised using the PWFAD procedure in the same manner as in the development of the original N-494 approach for ferritic materials

  10. Reliability and Sensitivity Analysis of Cast Iron Water Pipes for Agricultural Food Irrigation

    Directory of Open Access Journals (Sweden)

    Yanling Ni

    2014-07-01

    Full Text Available This study aims to investigate the reliability and sensitivity of cast iron water pipes for agricultural food irrigation. The Monte Carlo simulation method is used for fracture assessment and reliability analysis of cast iron pipes for agricultural food irrigation. Fracture toughness is considered as a limit state function for corrosion affected cast iron pipes. Then the influence of failure mode on the probability of pipe failure has been discussed. Sensitivity analysis also is carried out to show the effect of changing basic parameters on the reliability and life time of the pipe. The analysis results show that the applied methodology can consider different random variables for estimating of life time of the pipe and it can also provide scientific guidance for rehabilitation and maintenance plans for agricultural food irrigation. In addition, the results of the failure and reliability analysis in this study can be useful for designing of more reliable new pipeline systems for agricultural food irrigation.

  11. Precipitation kinetics in austenitic 18Cr-30Ni-Nb cast steel

    Directory of Open Access Journals (Sweden)

    M. Garbiak

    2008-08-01

    Full Text Available The study presents the results of investigations on the precipitation kinetics in austenitic 18%Cr-30%Ni cast steel stabilised with an addition of 1.84 wt% niobium. Phase analysis of isolates extracted from the alloy subjected to annealing within the temperature range of 600–1000oC during 10–1000 h was made. The phase constitution of the isolates mainly comprised niobium carbides of the NbC type and complex chromium carbides of the Cr23C6 type. In specimens annealed within the temperature range of 700–900oC, a high-silicon G phase was additionally identified. The highest kinetics of the precipitation process was recorded after annealing at the temperatures of 800 and 900oC.

  12. Abnormal image appearing in radiographic film of continuously cast austenite stainless steel

    International Nuclear Information System (INIS)

    Investigation of abnormal image appearance in radiographic films and the analysis of its cause have been performed with test pieces of coarse grain sizes cut from a continuously cast billet of austenitic stainless steel. The image is a long, narrow and stripped pattern in horizontally cut test piece and squamouse pattern in vertically cut test pieces, although the pattern of the macrostructure were identical. It has been experimentally verified that this abnormal image is caused mainly by X-ray diffraction which occurs when X-ray penetrates the solidified structure in the test piece and is not due to any segregation of chemical compositions; and further that the precipitated Δ-ferrite is the factor that affects the contrast of the abnormal image. (author)

  13. Evaluation of thermal stratification and primary water environment effects on fatigue life of austenitic piping

    International Nuclear Information System (INIS)

    During the last two decades, lots of efforts have been devoted to resolve thermal stratification phenomenon and primary water environment issues. While several effective methods were proposed especially in related to thermally stratified flow analyses and corrosive material resistance experiments, however, lack of details on specific stress and fatigue evaluation make it difficult to quantify structural behaviors. In the present work, effects of the thermal stratification and primary water are numerically examined from a structural integrity point of view. First, a representative austenitic nuclear piping is selected and its stress components at critical locations are calculated in use of four stratified temperature inputs and eight transient conditions. Subsequently, both metal and environmental fatigue usage factors of the piping are determined by manipulating the stress components in accordance with NUREG/CR-5704 as well as ASME B and PV Codes. Key findings from the fatigue evaluation with applicability of pipe and three-dimensional solid finite elements are fully discussed and a recommendation for realistic evaluation is suggested

  14. Improvement of austenitic pipings with welds-corrosion resistance, non-destructive testing and loadability

    International Nuclear Information System (INIS)

    Pipes made from austenitic materials are employed extensively in power plant technology and in the chemical industry. An important aspect is the integrity of the piping, proof of which is quite complex especially due to connecting welds. In the case of an inappropriate application of energy when welding, precipitations develop. For example, M23C6 type precipitations, which weaken the corrosion resistance considerably and give rise to residual stresses which interfere with the load stresses. Simultaneously wrinkles and notches can occur in the area of the root of the weld seam, which in general is medium contacting, and this increases stress and corrosion susceptibility and reduces the loadability as well as the critical crack size. This is especially disadvantageous, as due to the development of the microstructure with non-destructive testing measures, it is very unlikely that small cracks can be detected. In the contribution these influencing variables are covered quantitatively and the optimization possibilities are shown using experimental and numerical simulations. On real pipes of the dimension DN 200 the success of the measures undertaken dependant on the crack sizes, especially the loadability, is verified experimentally. (author)

  15. Report on Japanese performance demonstration examinations for depth sizing of SCC in austenitic stainless steel pipes

    International Nuclear Information System (INIS)

    The PD Center of Central Research Institute of Electric Power Industry (CRIEPI) commenced Performance Demonstration examinations for flaw depth sizing of austenitic stainless steel pipes in March 2006. As of January 2013, 37 examination sessions have been completed and 44 candidates have passed the examination. The total number of tests administered including re-tests and re-certification was 89. It was noted that depth sizing using a phased array plus the manual UT technique was the procedure most used by successful PD applicants. A major reason for failure is 'the overestimation caused by the lack of skill in distinguishing the base metal-to-weld metal interface echo and the SCC tip echo'. Moreover, the possibility of psychological bias is also incontrovertible because candidates are under pressure not to make a -4.4 mm critical mistake. (author)

  16. Crack growth of intergranular stress corrosion cracks in austenitic stainless steel pipes of boiling water reactors

    International Nuclear Information System (INIS)

    Intergranular stress corrosion cracking (IGSCC) of boiling water reactor (BWR) piping is considered from the crack growth rate point of view. Crack growth rate of sensitized austenitic stainless steel welds is dependent on the degree of sensitization of the material and the severity of the environment as well as the stress state. In evaluation of actual crack growth rate there are three major sources of uncertainty: knowledge of actual crack size and shape, actual stress distribution in he area of the crack and the degree of sensitization. In the report the crack growth calculations used in the USA and in Sweden are presented. Finally, the crack growth rate predictions based on mechanistic modelling of IGSCC and some needs of further research in Finland are considered

  17. Castings for stainless steel primary piping in PWR nuclear power plant

    International Nuclear Information System (INIS)

    Primary piping steel of Z3CN20-09M for nuclear power plant is melted by combination of electric furnace and AOD furnace, ferrite content of Z3CN20-09M are adjusted based on the compute result of Scharffler. Measures by enlarging the wall thickness of shell, decreasing inside diameter of the baffle, selecting greater g value and increasing machining allowances of internal surface, etc, in centrifugal casting process, sample of primary piping are cast. Measure results show that various performance of sample of primary piping the needs of RCC-M are without exception meet

  18. Cracking behavior of thermally aged and irradiated CF-8 cast austenitic stainless steel

    Science.gov (United States)

    Chen, Y.; Alexandreanu, B.; Chen, W.-Y.; Natesan, K.; Li, Z.; Yang, Y.; Rao, A. S.

    2015-11-01

    To assess the combined effect of thermal aging and neutron irradiation on the cracking behavior of CF-8 cast austenitic stainless steel, crack growth rate (CGR) and fracture toughness J-R curve tests were carried out on compact-tension specimens in high-purity water with low dissolved oxygen. Both unaged and thermally aged specimens were irradiated at ∼320 °C to 0.08 dpa. Thermal aging at 400 °C for 10,000 h apparently had no effect on the corrosion fatigue and stress corrosion cracking behavior in the test environment. The cracking susceptibility of CF-8 was not elevated significantly by neutron irradiation at 0.08 dpa. Transgranular cleavage-like cracking was the main fracture mode during the CGR tests, and a brittle morphology of delta ferrite was often seen on the fracture surfaces at the end of CGR tests. The fracture toughness J-R curve tests showed that both thermal aging and neutron irradiation can induce significant embrittlement. The loss of fracture toughness due to neutron irradiation was more pronounced in the unaged than aged specimens. After neutron irradiation, the fracture toughness values of the unaged and aged specimens were reduced to a similar level. G-phase precipitates were observed in the aged and irradiated specimens with or without prior aging. The similar microstructural changes resulting from thermal aging and irradiation suggest a common microstructural mechanism of inducing embrittlement in CF-8.

  19. Methods for the In-Situ Characterization of Cast Austenitic Stainless Steel Microstructures

    International Nuclear Information System (INIS)

    Cast austenitic stainless steel (CASS) that was commonly used in U.S. nuclear power plants is a coarse-grained, elastically anisotropic material. Its engineering properties made it a material of choice for selected designs of nuclear power reactor systems. However, the fabrication processes result in a variety of coarse-grain microstructures that make current ultrasonic in-service inspection of components quite challenging. To address inspection needs, new ultrasonic inspection approaches are being sought. However, overcoming the deleterious and variable effects of the microstructure on the interrogating ultrasonic beam may require knowledge of the microstructure, for potential optimization of inspection parameters to enhance the probability of detection (POD). The ability to classify microstructure type (e.g. polycrystalline or columnar) has the potential to guide selection of optimal NDE approaches. This paper discusses the application of ultrasonic and electromagnetic methods for classifying CASS microstructures, when making measurements from the outside surface of the component. Results to date demonstrate the potential of these measurements to discriminate between two consistent microstructures - equiaxed-grain material versus columnar-grain material. The potential for fusion of ultrasonic and electromagnetic measurements for in-situ microstructure characterization in CASS materials will be explored.

  20. Automated flaw detection scheme for cast austenitic stainless steel weld specimens using Hilbert-Huang transform of ultrasonic phased array data

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Tariq; Majumdar, Shantanu; Udpa, Lalita [Dept. of Electrical and Comupter Engineering, Michian State University, East Lansing, MI 48824 (United States); Ramuhalli, Pradeep; Crawford, Susan; Diaz, Aaron; Anderson, Michael T. [Pacific Northwest National Laboratory, Richland, WA 99354 (United States)

    2012-05-17

    The objective of this work is to develop processing algorithms to detect and localize flaws using ultrasonic phased-array data. Data was collected on cast austenitic stainless stell (CASS) weld specimens onloan from the U.S. nuclear power industry' Pressurized Walter Reactor Owners Group (PWROG) traveling specimen set. Each specimen consists of a centrifugally cast stainless stell (CCSS) pipe section welded to a statically cst(SCSS) or wrought (WRSS) section. The paper presents a novel automated flaw detection and localization scheme using low frequency ultrasonic phased array inspection singals from the weld and heat affected zone of the based materials. The major steps of the overall scheme are preprocessing and region of interest (ROI) detection followed by the Hilbert-Huang transform (HHT) of A-scans in the detected ROIs. HHT offers time-frequency-energy distribution for each ROI. The Accumulation of energy in a particular frequency band is used as a classification feature for the particular ROI.

  1. Computation of Phase Fractions in Austenite Transformation with the Dilation Curve for Various Cooling Regimens in Continuous Casting

    Science.gov (United States)

    Dong, Zhihua; Chen, Dengfu; Long, Mujun; Li, Wei; Chen, Huabiao; Vitos, Levente

    2016-06-01

    A concise model is applied to compute the microstructure evolution of austenite transformation by using the dilation curve of continuously cast steels. The model is verified by thermodynamic calculations and microstructure examinations. When applying the model, the phase fractions and the corresponding transforming rates during austenite transformation are investigated at various cooling rates and chemical compositions. In addition, ab initio calculations are performed for paramagnetic body-centered-cubic Fe to understand the thermal expansion behavior of steels at an atomic scale. Results indicate that by increasing the cooling rate, the final volume fraction of ferrite/pearlite will gradually increase/decrease with a greater transforming rate of ferrite. The ferrite fraction increases after austenite transformation with lowering of the carbon content and increasing of the substitutional alloying fractions. In the austenite transformation, the thermal expansion coefficient is sequentially determined by the forming rate of ferrite and pearlite. According to the ab initio theoretical calculations for the single phase of ferrite, thermal expansion emerges from magnetic evolution and lattice vibration, the latter playing the dominant role. The theoretical predictions for volume and thermal expansion coefficient are in good agreement with the experimental data.

  2. Development of Cast Alumina-forming Austenitic Stainless Steel Alloys for use in High Temperature Process Environments

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan [ORNL; Yamamoto, Yukinori [ORNL; Brady, Michael P [ORNL; Pint, Bruce A [ORNL; Pankiw, Roman [Duraloy Technologies Inc; Voke, Don [Duraloy Technologies Inc

    2015-01-01

    There is significant interest in the development of alumina-forming, creep resistant alloys for use in various industrial process environments. It is expected that these alloys can be fabricated into components for use in these environments through centrifugal casting and welding. Based on the successful earlier studies on the development of wrought versions of Alumina-Forming Austenitic (AFA) alloys, new alloy compositions have been developed for cast products. These alloys achieve good high-temperature oxidation resistance due to the formation of protective Al2O3 scales while multiple second-phase precipitation strengthening contributes to excellent creep resistance. This work will summarize the results on the development and properties of a centrifugally cast AFA alloy. This paper highlights the strength, oxidation resistance in air and water vapor containing environments, and creep properties in the as-cast condition over the temperature range of 750°C to 900°C in a centrifugally cast heat. Preliminary results for a laboratory cast AFA composition with good oxidation resistance at 1100°C are also presented.

  3. An experience with in-service fabrication and inspection of austenitic stainless steel piping in high temperature sodium system

    International Nuclear Information System (INIS)

    Highlights: • Procedure for changing 304L SS pipe to 316L SS in sodium loop has been established. • Hot leg made of 304L SS was isolated from existing cold leg made of 316LN SS. • Innovative welding was used in joining the new 316L SS pipe with existing 316LN SS. • The old components of 304L SS piping have been integrated with the new piping. - Abstract: A creep testing facility along with dynamic sodium loop was installed at Indira Gandhi Centre for Atomic Research, Kalpakkam, India to assess the creep behavior of fast reactor structural materials in flowing sodium. Type 304L austenitic stainless steel was used in the low cross section piping of hot-leg whereas 316LN austenitic stainless steel in the high cross section cold-leg of the sodium loop. The intended service life of the sodium loop was 10 years. The loop has performed successfully in the stipulated time period. To enhance its life time, it has been decided to replace the 304L piping with 316L piping in the hot-leg. There were more than 300 welding joints involved in the integration of cold-leg with the new 316L hot-leg. Continuous argon gas flow was maintained in the loop during welding to avoid contamination of sodium residue with air. Several innovative welding procedures have been adopted for joining the new hot-leg with the existing cold-leg in the presence of sodium residue adopting TIG welding technique. The joints were inspected for 100% X-ray radiography and qualified by performing tensile tests. The components used in the discarded hot-leg were retrieved, cleaned and integrated in the renovated loop. A method of cleaning component of sodium residue has been established. This paper highlights the in-service fabrication and inspection of the renovation

  4. Residual Stresses Due to Circumferential Girth Welding of Austenitic Stainless Steel Pipes

    Science.gov (United States)

    Tarak, Farzan

    Welding, as a joining method in fabrication of engineering products and structural elements, has a direct influence on thermo-mechanical behavior of components in numerous structural applications. Since these thermo-mechanical behaviors have a major role in the life of welding components, predicting thermo-mechanical effects of welding is a major factor in designing of welding components. One of the major of these effects is generation of residual stresses due to welding. These residual stresses are not the causes of failure in the components solely, but they will add to external loads and stresses in operating time. Since, experimental methods are time consuming and expensive, computational simulation of welding process is an effective method to calculate these residual stresses. This investigation focuses on the evaluation of residual stresses and distortions due to circumferential girth welding of austenitic stainless steel pipes using the commercial finite element software ESI Visual-Environment and SYSWELDRTM to simulate welding process. Of particular importance is the comparison of results from three different types of mechanics models: 1) Axisymmetric, 2) Shell, and 3) Full 3-D.

  5. Z factors for aged cast duplex stainless steel pipes and welds

    International Nuclear Information System (INIS)

    This paper provides the Z factors of aged cast duplex stainless steel pipes and their welds with circumferential through-wall crack obtained form the Japanese material data. Z factors are used for elastic-plastic evaluation in ASME Code Section XI. Stress-strain curve and J-resistance curve taken from the base metal of cast duplex stainless steel with ferrite contents of about 23.5% and its adjoining welds of TIG (Tungsten Inert Gas), SMAW (Shielded Metal Arc Welding), and SAW (Submerged Arc Welding) were used. These material were aged for 20000 to 40000 hours at 400 degrees C. The calculated Z factors were formulated in using the approximation with a linear equation of logarithm to the base ten. The proposed Z factors were compared with the Z factors in ASME Code Section XI. In the case of TIG and SMAW, the proposed Z factors give almost the same as the Z factors in ASME Code Section XI. In the case of SAW and cast stainless steel, the proposed Z factors were higher than the Z factors in ASME Code Section XI. Besides, In order to verify the availability of proposed Z factors, the critical bending moments by Z factors were compared with experimental data of aged cast duplex stainless steel pipes. The proposed Z factor for SAW and aged cast duplex stainless steel would be applied to estimate the failure moment of aged cast duplex stainless steel pipes. (author)

  6. Effects of Thermocapillary Forces during Welding of 316L-Type Wrought, Cast and Powder Metallurgy Austenitic Stainless Steels

    CERN Document Server

    Sgobba, Stefano

    2003-01-01

    The Large Hadron Collider (LHC) is now under construction at the European Organization for Nuclear Research (CERN). This 27 km long accelerator requires 1248 superconducting dipole magnets operating at 1.9 K. The cold mass of the dipole magnets is closed by a shrinking cylinder with two longitudinal welds and two end covers at both extremities of the cylinder. The end covers, for which fabrication by welding, casting or Powder Metallurgy (PM) was considered, are dished-heads equipped with a number of protruding nozzles for the passage of the different cryogenic lines. Structural materials and welds must retain high strength and toughness at cryogenic temperature. AISI 316L-type austenitic stainless steel grades have been selected because of their mechanical properties, ductility, weldability and stability of the austenitic phase against low-temperature spontaneous martensitic transformation. 316LN is chosen for the fabrication of the end covers, while the interconnection components to be welded on the protrud...

  7. Long time thermal aging of static cast SA 351 grade CF8M austenitic stainless steel elbow from Beznau unit 2

    International Nuclear Information System (INIS)

    Due to the degradation of the Inconel steam generator tubing, NOK replaced steam generators (SGs) in both Beznau Units 1 and 2. Beznau Unit 1 SGs were replaced in 1993 after approximately 175,000 hours of operation. Beznau Unit 2 SGs were replaced in 1998 after approximately 207,000 hours of operation. During the replacement of the SGs, NOK also replaced the hot and crossover leg elbows directly attached to the SGs. Thus SA 351 Grade CF8M austenitic stainless steel material from the hot and cold leg elbows including the weld metal joining the elbows to piping were available for evaluation of thermal aging. Thermal embrittlement of cast duplex stainless steel, in the case of Beznau Units 1 and 2 SG elbows SA 351 Grade CF8M, can result in either cleavage of the ferrite or separation of the ferrite/austenite grain boundaries. Thermal aging of cast duplex stainless steel at operating temperatures of Pressurized Water Reactors (PWR) can lead to precipitation of phases in the ferrite. The temperature at which the precipitation of the additional phases in the ferrite is decreased in Mo-bearing CF8M steels. Testing of the thermally aged (175,000 hours) Beznau Unit 1 crossover leg elbow and hot leg elbow materials was completed in 1996. Both the crossover leg and hot leg elbows'material exhibited relatively high fracture toughness values after 175,000 hours of operation. This paper presents the fracture toughness and ferrite measurement test results from the thermally aged (207,000 hours) Beznau Unit 2 hot leg materials. The hot leg elbow static casting material (SA 351 Grade CF8M) exhibited relatively high fracture toughness properties, JIC and Tearing Modulus, after thermal aging for 207,000 hours at operating temperature. The test results of the fracture mechanics specimens showed that the degradation had saturated. Comparison of the fracture toughness values used in the Leak-Before Break (LBB) analysis with the fracture toughness values obtained for the Beznau Unit 2

  8. Resonant modes in centrifugally cast stainless steel (CCSS) pipes

    International Nuclear Information System (INIS)

    In general, Lamb-wave modes can be grouped into two fundamental types: symmetric modes or antisymmetric modes, depending on whether their displacement vector is symmetric or antisymmetric with respect to the median plane of the solid plate. The resonant modes of a CCSS pipe are more general because a pipe is a cylindrical shell and, in the case of columnar-grain CCSS, has to be treated as a anisotropic medium. In this paper, we evaluate how the resonant modes of a CCSS pipe deviate from those of an isotropic plate. The deviation due to either the material anisotropy or the cylindrical curvature is examined. We focus on the Lamb-type modes of a thick cylindrical shell and model the CCSS as a transversely isotropic plate. For reference, a quick review of the dispersion properties of an isotropic plate is provided

  9. Development of Stronger and More Reliable Cast Austenitic Stainless Steels (H-Series) Based on Scientific and Design Methodology

    Energy Technology Data Exchange (ETDEWEB)

    Pankiw, Roman I; Muralidharan, G. (Murali); Sikka, Vinod K.

    2006-06-30

    The goal of this project was to increase the high-temperature strength of the H-Series of cast austenitic stainless steels by 50% and the upper use temperature by 86 to 140 degrees fahrenheit (30 to 60 degrees celsius). Meeting this goal is expected to result in energy savings of 35 trillion Btu/year by 2020 and energy cost savings of approximately $230 million/year. The higher-strength H-Series cast stainless steels (HK and HP type) have applications for the production of ethylene in the chemical industry, for radiant burner tubes and transfer rolls for secondary processing of steel in the steel industry, and for many applications in the heat treating industry, including radiant burner tubes. The project was led by Duraloy Technologies, Inc., with research participation by Oak Ridge National Laboratory (ORNL) and industrial participation by a diverse group of companies.

  10. Microstructural evolution in austenitic heat-resistant cast steel 35Cr25Ni12NNbRE during long-term service

    International Nuclear Information System (INIS)

    The microstructural evolution of austenitic heat-resistant cast steel 35Cr25Ni12NNbRE during aging and long-term service was investigated using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The microstructure of the as cast steel consists of the dendritic austenite, the block-like eutectic carbide M7C3 spreaded among austenitic dendrite, and a small quantity of M23C6 carbide. The microstructure of the steel aged at 600 deg. C consists of eutectic carbide M23C6 transformed from eutectic carbide M7C3 and dendritic austenite in which fine secondary carbide particles M23C6 precipitated. The precipitated carbide M23C6 kept a cubic-cubic orientation relationship (OR) with austenite matrix. There existed a carbide precipitation free zone (PFZ) around the eutectic carbide. For the long-term serviced samples, the secondary carbide precipitated in the austenite strikingly increased and the PFZ disappeared. Part of the M23C6 transformed into M6C, which always kept a twin OR, [114]M6C//[110]A//[110]M23C6, with the austenite and the M23C6 secondary carbide. In addition, a small quantity of σ phase FeCr and ε-Cr2N were also identified. The effects of alloy composition and service condition on the microstructural evolution of the steel were discussed.

  11. Cracking in stabilized austenitic stainless steel piping of German boiling water reactors - characteristic features and root cause

    International Nuclear Information System (INIS)

    Cracks have been found in the welds of piping systems made from stabilized austenitic stainless steels in German boiling water reactors (BWR). In the course of the intensive failure analysis metallographic examinations, microstructural investigations by electron microscopy, corrosion experiments and welding tests have been performed. The results show that cracking under the given medium conditions is due to intergranular stress corrosion cracking (IGSCC) in those parts of the heat affected zone (HAZ) which are overheated during welding and where solution of titanium carbides and subsequent precipitation of chromium carbides and depletion of chromium along the affected grain boundaries could occur. (orig.)

  12. Internal Crack Propagation in a Continuously Cast Austenitic Stainless Steel Analyzed by Actual Residual Stress Tensor Distributions

    Science.gov (United States)

    Saito, Youichi; Tanaka, Shun-Ichiro

    2016-04-01

    Initiation, propagation, and termination of internal cracks in a continuously cast austenitic stainless steel has been investigated with emphasis on stress loading of the solidified shell during casting. Cracks were formed at the center of the slab, parallel to the width of the cast, and were observed near the narrow faces. Optimized two-dimensional X-ray diffraction method was employed to measure residual stress tensor distributions around the cracks in the as-cast slab with coarse and strongly preferentially oriented grains. The tensor distributions had a sharp peak, as high as 430 MPa, at the crack end neighboring the columnar grains. On the other hand, lower values were measured at the crack end neighboring the equiaxed grains, where the local temperatures were higher during solidification. The true residual stress distributions were determined by evaluating the longitudinal elastic constant for each measured position, resulting in more accurate stress values than before. Electron probe micro-analysis at the terminal crack position showed that Ni, Ti, and Si were concentrated at the boundaries of the equiaxed grains, where the tensile strength was estimated to be lower than at the primary grains. A model of the crack formation and engineering recommendations to reduce crack formation are proposed.

  13. Characteristics of low nickel ferritic-austenitic corrosion resistant cast steel

    OpenAIRE

    B. Kalandyk; Zapała, R.; Sobula, S.; M. Górny; Ł. Boroń

    2014-01-01

    The article presents the results of microscopic examinations of corrosion resistant cast steel with reduced nickel content obtained in a test casting with varying wall thickness. Investigations were carried out in as-cast condition and after heat treatment. Regardless of the casting wall thickness, increasing the manganese and nitrogen content to about 5 % and 2 500 ppm, respectively, yields the material with a two-phase microstructure containing ferrite in an amount of 55,6 ÷ 57,2 % (magneti...

  14. In situ TEM study of G-phase precipitates under heavy ion irradiation in CF8 cast austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei-Ying [Argonne National Laboratory, Argonne, IL 60439 (United States); University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Li, Meimei; Zhang, Xuan; Kirk, Marquis A.; Baldo, Peter M. [Argonne National Laboratory, Argonne, IL 60439 (United States); Lian, Tiangan [Electric Power Research Institute, Palo Alto, CA 94304 (United States)

    2015-09-15

    Thermally-aged cast austenitic stainless steels (CASS) CF8 was irradiated with 1 MeV Kr ions at 300, 350 and 400 °C to 1.88 × 10{sup 19} ions/m{sup 2} (∼3 dpa) at the IVEM-Tandem Facility at the Argonne National Laboratory. Before irradiation, the distribution of G-phase precipitates in the ferrite showed spatial variations, and both their size and density were affected by the ferrite–austenite phase boundary and presence of M{sub 23}C{sub 6} carbides. Under 300 °C irradiation, in situ TEM observation showed G-phase precipitates were relatively unchanged in the vicinity of the phase boundary M{sub 23}C{sub 6} carbides, while the density of G-phase precipitates increased with increasing dose within the ferrite matrix. Coarsening of G-phase precipitates was observed in the vicinity of phase boundary M{sub 23}C{sub 6} carbides at 350 °C and 400 °C.

  15. Assessment of thermal aging embrittlement of cast austenitic stainless steel components in the Babcock and Wilcox -designed PWR reactor internals

    International Nuclear Information System (INIS)

    The currently operating Babcock and Wilcox (BW) designed pressurized water reactors (PWRs) were constructed during the late sixties and seventies. Some of the reactor internals components were fabricated from cast austenitic stainless steel (CASS). The selection of CASS for the internals components was made to expedite the construction schedule by reducing machining and allowing production in large quantities. Since then, test data have shown that some CASS materials are susceptible to thermal aging embrittlement at PWR operating temperatures and its effect on functionality is of concern. Recently, the US nuclear power industry has developed inspection and evaluation guidelines (MRP-227, Rev.0) for managing aging degradation in PWR reactor internals for both the current and extended license periods. The MRP-227, Rev.0 guidelines recommend additional inspections for certain internals components including CASS components in BW PWRs due to thermal aging embrittlement concerns. The thermal aging embrittlement susceptibility for CASS can be assessed by the casting method and ferrite content if sufficient information in the original fabrication records is available. AREVA NP has performed a fabrication records search to identify several CASS components in the BW PWR internals and reviewed the archived fabrication records. A database has been assembled as a result of this records search. Based on the fabrication records, the ferrite content is determined using Hull's equivalent factors. Grade CF8 castings (without molybdenum) have been found to not be susceptible to thermal aging embrittlement. However, thermal aging embrittlement is a potential concern for Grade CF3M castings (containing 2 to 3% molybdenum). As a result of this assessment, several CASS components in the BW PWRs are concluded to not be susceptible to thermal aging embrittlement. The findings provide the basis for the removal of these CASS components from the additional inspection requirements in MRP-227

  16. Ferrite Measurement in Austenitic and Duplex Stainless Steel Castings - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Lundin, C.D.; Zhou, G.; Ruprecht, W.

    1999-08-01

    The ability to determine ferrite rapidly, accurately and directly on a finished casting, in the solution annealed condition, can enhance the acceptance, save on manufacturing costs and ultimately improve service performance of duplex stainless steel cast products. If the suitability of a non-destructive ferrite determination methodology can be demonstrated for standard industrial measurement instruments, the production of cast secondary standards for calibration of these instruments is a necessity. With these concepts in mind, a series of experiments were carried out to demonstrate, in a non-destructive manner, the proper methodology for determining ferrite content. The literature was reviewed, with regard to measurement techniques and vagaries, an industrial ferrite measurement round-robin was conducted, the effects of casting surface finish, preparation of the casting surface for accurate measurement and the evaluation of suitable means for the production of cast secondary standards for calibration were systematically investigated. The data obtained from this research program provide recommendations to ensure accurate, repeatable, and reproducible ferrite measurement and qualifies the Feritscope for field use on production castings.

  17. Ferrite Measurement in Austenitic and Duplex Stainless Steel Castings - Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Lundin, C.D.; Zhou, G.; Ruprecht, W.

    1999-08-01

    The ability to determine ferrite rapidly, accurately and directly on a finished casting, in the solution annealed condition, can enhance the acceptance, save on manufacturing costs and ultimately improve service performance of duplex stainless steel cast products. If the suitability of a non-destructive ferrite determination methodology can be demonstrated for standard industrial measurement instruments, the production of cast secondary standards for calibration of these instruments is a necessity. With these concepts in mind, a series of experiments were carried out to demonstrate, in a non-destructive manner, the proper methodology for determining ferrite content. The literature was reviewed, with regard to measurement techniques and vagaries, an industrial ferrite measurement round-robin was conducted, the effects of casting surface finish, preparation of the casting surface for accurate measurement and the evaluation of suitable means for the production of cast secondary standards for calibration were systematically investigated. The data obtained from this research program provides recommendations to insure accurate, repeatable and reproducible ferrite measurement and qualifies the Feritscope for field use on production castings.

  18. Residual stress and microstructure evolution by manufacturing processes for welded pipe joint in austenitic stainless steel type 316L

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) has been observed near the heat affected zone (HAZ) of welded pipe joint made of austenitic stainless steel type 316L, even though sensitization is not observed. Therefore, It can be considered that the effect of residual stress on SCC is more important. In the joining process of pipes, butt-welding is conducted after machining. Residual stress is generated by both processes. In case of welding after machining, it can be considered that residual stress due to machining is changed by welding thermal cycle. In this study, residual stress and microstructure evolution due to manufacturing processes is investigated. Change of residual stress distribution caused by processing history is examined by X-ray diffraction method. Residual stress distribution has a local maximum stress in the middle temperature range of the HAZ caused by processing history. Hardness measurement result also has a local maximum hardness in the same range of the HAZ. By using FE-SEM/EBSD, it is clarified that microstructure shows recovery in the high temperature range of HAZ. Therefore, residual stress distribution is determined by microstructure evolution and superposition effect of processing history. In summary, not only any part of manufacturing processes such as welding or machining but also treating all processes as processing history of pipes are important to evaluate SCC. (author)

  19. Mechanized radiation testing of austenitic pipe welds. Testing of media filled pipes and determination of the flaw depth by tomosynthesis

    International Nuclear Information System (INIS)

    A compact detection system was built for multi-angle inspection of pipes, consisting of a high-sensitivity radiometric line scanner and an ultrasonic manipulator. Improved flaw imaging quality is achieved with this system as compared to film radiography. Measurements have been carried out on site in a nuclear power plant and in a laboratory. Better flaw imaging quality was also achieved in the testing of water-filled pipes. Non-linear tomosynthesis was applied for processing and interpretation of measured data. The system delivers considerably better images of planary materials inhomogeneitites, (such as cracks and lack-of-bond defects). (orig./CB)

  20. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kiran M. Kothari; Gerard T. Pittard

    2003-01-01

    Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. The bell-and-spigot joints tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple cast-iron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs while the pipe remains in service by traveling through the pipe, cleaning each joint surface, and attaching a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service (which results in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1--Program Management was previously completed. Two reports, one describing the program management plan and the other consisting of the technology assessment, were submitted to the DOE COR in the first quarter. Task 2--Establishment of Detailed Design Specifications and Task 3--Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves are now well underway. First-quarter activities included conducting detailed analyses to determine the capabilities of coiled-tubing locomotion for entering and repairing gas mains and the first design iteration of the joint-sealing sleeve. The maximum horizontal reach of coiled tubing inside a pipeline before buckling prevents further access was calculated for a

  1. Study of biofilm influenced corrosion on cast iron pipes in reclaimed water

    Science.gov (United States)

    Zhang, Haiya; Tian, Yimei; Wan, Jianmei; Zhao, Peng

    2015-12-01

    Biofilm influenced corrosion on cast iron pipes in reclaimed water was systemically studied using the weight loss method and electrochemical impedance spectroscopy (EIS). The results demonstrated that compared to sterile water, the existence of the biofilm in reclaimed water promoted the corrosion process significantly. The characteristics of biofilm on cast iron coupons were examined by the surface profiler, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The bacterial counts in the biofilm were determined using the standard plate count method and the most probable number (MPN). The results demonstrated that the corrosion process was influenced by the settled bacteria, EPS, and corrosion products in the biofilm comprehensively. But, the corrosion mechanisms were different with respect to time and could be divided into three stages in our study. Furthermore, several corresponding corrosion mechanisms were proposed for different immersion times.

  2. Residual stress distribution in austenitic stainless steel pipe butt-welded joint measured by neutron diffraction technique

    International Nuclear Information System (INIS)

    Residual stress is inevitable consequence of welding or manufacturing process, which might greatly affect propagation of high-cycle fatigue or SCC crack. In order to evaluate damages due to the crack, it is required to estimate residual stress and to reflect them to the evaluation process as well. The magnitude and distribution of residual stress greatly depend on the individual process of welding or manufacturing, while the accuracy of prediction or measurement is still insufficient. This paper reports the result of residual stress measurement of butt-welded pipe made of austenitic stainless steel. It also intended to improve prediction and measurement techniques concerning to residual stress. The measurement was conducted by neutron diffraction technique employing the diffractometer for residual stress analysis developed by Japan Atomic Energy Agency. The measured results showed typical characteristics of butt-welded pipe both in decline of stress along axial direction and in radial distribution of bending due to axial stress. The measured result agreed qualitatively with the result predicted by the finite element analysis. A quantitative comparison between measured result and analysis showed a shift of the measured stress toward higher tensile. The measured result was also compared with the results by X-ray diffraction and strain-gauge methods to grasp the distinctive results of the methods. (author)

  3. MICROSTRUCTURAL CHARACTERIZATION OF PRIMARY COOLANT PIPE STEEL

    OpenAIRE

    Miller, M; Bentley, J.

    1986-01-01

    Atom probe field-ion microscopy, analytical electron microscopy, and optical microscopy have been used to investigate the changes that occur in the microstructure of cast CF 8 primary coolant pipe stainless steel long term thermal aging. The cast duplex microstructure consisted of austenite with 15% δ-ferrite. Investigation of the aged material revealed that the ferrite spinodally decomposed into a fine scaled network of α and α'. A fine G-phase precipitate was also observed in the ferrite. T...

  4. Experimental and numerical assessment of thermal fatigue in 316 austenitic steel pipes

    OpenAIRE

    PAFFUMI Elena; Nilsson, Karl-Fredrik; Szaraz, Zoltan

    2013-01-01

    This paper presents an experimental and numerical investigation of thermal fatigue of 316L steel pipe components with 14 mm wall thickness heated by induction to 300–550 °C on the outer surface and cyclically cooled internally with room temperature water. The damage is initiated as network of surface cracks where some cracks become dominant. At 550 °C the pipe fails after typically 50,000 cycles whereas at 300 °C the deepest cracks have only penetrated half the thickness after 250,000 cycles....

  5. Modeling of ultrasonic propagation in heavy-walled centrifugally cast austenitic stainless steel based on EBSD analysis.

    Science.gov (United States)

    Chen, Yao; Luo, Zhongbing; Zhou, Quan; Zou, Longjiang; Lin, Li

    2015-05-01

    The ultrasonic inspection of heavy-walled centrifugally cast austenitic stainless steel (CCASS) is challenging due to the complex metallurgical structure. Numerical modeling could provide quantitative information on ultrasonic propagation and plays an important role in developing advanced and reliable ultrasonic inspection techniques. But the fundamental obstacle is the accurate description of the complex metallurgical structure. To overcome this difficulty, a crystal orientation map of a CCASS specimen in the 96 mm × 12 mm radial-axial cross section was acquired based on the electron backscattered diffraction (EBSD) technique and it was used to describe the coarse-grained structure and grain orientation. A model of ultrasonic propagation for CCASS was built according to the EBSD map. The ultrasonic responses of the CCASS sample were also tested. Some experimental phenomena such as structural noise and signal distortion were reproduced. The simulated results showed a good consistence with the experiments. The modeling method is expected to be effective for the precise interpretation of ultrasonic propagation in the polycrystalline structures of CCASS. PMID:25670411

  6. Behavior of surface residual stress in explosion hardened high manganese austenitic cast steel due to repeated impact loads

    International Nuclear Information System (INIS)

    Explosion hardened high manganese austenitic cast steel is being tried for rail crossing recently. From the previous studies, it became clear that high tensile residual stress was generated in the hardened surface layer by explosion and microcracks were observed. In this study, therefore, the behavior of surface residual stress in explosion hardened steel due to repeated impact loads was examined and compared with those of the original and shot peened steels. The results obtained are summarized as follows: (1) In the initial stage of the repetition of impact, high tensile surface residual stress in explosion hardened steel decreased rapidly with the repetition of impact, while those of the original and shot peened steels increased rapidly. This difference was attributed to the difference in depth of the work hardened layer in three testing materials. (2) Beyond 20 impacts the residual stress of three test specimens decreased gradually, and at more than 2000 impacts the compressive stress of about 500 MPa was produced regardless of the histories of working of testing materials. (3) The linear law in the second stage of residual stress fading was applicable to this case, and the range of the linear relationship was related to the depth of the work hardened layer of testing material. (4) From the changes in half-value breadth and peak intensity of diffraction X-ray, it was supposed that a peculiar microscopic strain exists in explosion hardened steel. (author)

  7. Effect of aging on the predicted maximum moment-carrying capacity of circumferentially cracked cast stainless steel pipe

    International Nuclear Information System (INIS)

    Cast stainless steel used in LWR primary system components such as valve bodies, pump castings, pipe fittings, and piping is susceptible to thermal embrittlement at reactor operating temperatures, 280-320 C (536-608 F). This process of thermal aging causes an increase in the hardness and ultimate tensile strength of the steel, and at the same time a decrease in toughness. Work at Argonne National Laboratories (ANL) has shown that such thermal embrittlement due to changes in the microstructure can occur during the reactor lifetime of 40 years. The effect of this thermal degradation on the load- carrying capacity of circumferentially cracked piping is the subject of this work. In this study, both lower-bound and typical values of the J-R curves and the tensile properties for CF8M and CF8A cast stainless steels, which have been artificially aged to simulate 4, 8, 16, 32, and 48 years of service at 300 C (572 F), were used to predict the maximum load-carrying capacity of circumferentially cracked pipes. The effect of aging, that is, reduced toughness and increased strength, for different pipe diameters, crack geometries [i.e., through-wall cracks (TWC) and surface cracks (SC)], and crack sizes has been investigated. Since complete stress-strain curve fits as a function of aging were not available at this time, only three analyses methods could be used. The three analyses methods used to estimate the maximum load-carrying capacity of cracked pipes were: (1) a J-estimation scheme for TWC pipes developed by Paris, (2) a Plastic-Zone-Screening Criteria (DPZP) developed at Battelle which is applicable to both TWC and SC pipe, and (3) the R6 Option 1 method developed by CEGB which is also applicable for both TWC and SC pipe

  8. Assessment of Crack Detection in Heavy-Walled Cast Stainless Steel Piping Welds Using Advanced Low-Frequency Ultrasonic Methods

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Michael T.; Crawford, Susan L.; Cumblidge, Stephen E.; Denslow, Kayte M.; Diaz, Aaron A.; Doctor, Steven R.

    2007-03-01

    Studies conducted at the Pacific Northwest National Laboratory in Richland, Washington, have focused on assessing the effectiveness and reliability of novel approaches to nondestructive examination (NDE) for inspecting coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the U.S. Nuclear Regulatory Commission on the effectiveness and reliability of advanced NDE methods as related to the inservice inspection of safety-related components in pressurized water reactors (PWRs). This report provides progress, recent developments, and results from an assessment of low frequency ultrasonic testing (UT) for detection of inside surface-breaking cracks in cast stainless steel reactor piping weldments as applied from the outside surface of the components. Vintage centrifugally cast stainless steel piping segments were examined to assess the capability of low-frequency UT to adequately penetrate challenging microstructures and determine acoustic propagation limitations or conditions that may interfere with reliable flaw detection. In addition, welded specimens containing mechanical and thermal fatigue cracks were examined. The specimens were fabricated using vintage centrifugally cast and statically cast stainless steel materials, which are typical of configurations installed in PWR primary coolant circuits. Ultrasonic studies on the vintage centrifugally cast stainless steel piping segments were conducted with a 400-kHz synthetic aperture focusing technique and phased array technology applied at 500 kHz, 750 kHz, and 1.0 MHz. Flaw detection and characterization on the welded specimens was performed with the phased array method operating at the frequencies stated above. This report documents the methodologies used and provides results from laboratory studies to assess baseline material noise, crack detection, and length-sizing capability for low-frequency UT in cast stainless steel piping.

  9. Assessment of Crack Detection in Heavy-Walled Cast Stainless Steel Piping Welds Using Advanced Low-Frequency Ultrasonic Methods

    International Nuclear Information System (INIS)

    Studies conducted at the Pacific Northwest National Laboratory in Richland, Washington, have focused on assessing the effectiveness and reliability of novel approaches to nondestructive examination (NDE) for inspecting coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the U.S. Nuclear Regulatory Commission on the effectiveness and reliability of advanced NDE methods as related to the inservice inspection of safety-related components in pressurized water reactors (PWRs). This report provides progress, recent developments, and results from an assessment of low frequency ultrasonic testing (UT) for detection of inside surface-breaking cracks in cast stainless steel reactor piping weldments as applied from the outside surface of the components. Vintage centrifugally cast stainless steel piping segments were examined to assess the capability of low-frequency UT to adequately penetrate challenging microstructures and determine acoustic propagation limitations or conditions that may interfere with reliable flaw detection. In addition, welded specimens containing mechanical and thermal fatigue cracks were examined. The specimens were fabricated using vintage centrifugally cast and statically cast stainless steel materials, which are typical of configurations installed in PWR primary coolant circuits. Ultrasonic studies on the vintage centrifugally cast stainless steel piping segments were conducted with a 400-kHz synthetic aperture focusing technique and phased array technology applied at 500 kHz, 750 kHz, and 1.0 MHz. Flaw detection and characterization on the welded specimens was performed with the phased array method operating at the frequencies stated above. This report documents the methodologies used and provides results from laboratory studies to assess baseline material noise, crack detection, and length-sizing capability for low-frequency UT in cast stainless steel piping

  10. Development of Stronger and More Reliable Cast Austenitic Stainless Steels (H-Series) Based on Scientific Design Methodology

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, G.; Sikka, V.K.; Pankiw, R.I.

    2006-04-15

    The goal of this program was to increase the high-temperature strength of the H-Series of cast austenitic stainless steels by 50% and upper use temperature by 86 to 140 F (30 to 60 C). Meeting this goal is expected to result in energy savings of 38 trillion Btu/year by 2020 and energy cost savings of $185 million/year. The higher strength H-Series of cast stainless steels (HK and HP type) have applications for the production of ethylene in the chemical industry, for radiant burner tubes and transfer rolls for secondary processing of steel in the steel industry, and for many applications in the heat-treating industry. The project was led by Duraloy Technologies, Inc. with research participation by the Oak Ridge National Laboratory (ORNL) and industrial participation by a diverse group of companies. Energy Industries of Ohio (EIO) was also a partner in this project. Each team partner had well-defined roles. Duraloy Technologies led the team by identifying the base alloys that were to be improved from this research. Duraloy Technologies also provided an extensive creep data base on current alloys, provided creep-tested specimens of certain commercial alloys, and carried out centrifugal casting and component fabrication of newly designed alloys. Nucor Steel was the first partner company that installed the radiant burner tube assembly in their heat-treating furnace. Other steel companies participated in project review meetings and are currently working with Duraloy Technologies to obtain components of the new alloys. EIO is promoting the enhanced performance of the newly designed alloys to Ohio-based companies. The Timken Company is one of the Ohio companies being promoted by EIO. The project management and coordination plan is shown in Fig. 1.1. A related project at University of Texas-Arlington (UT-A) is described in Development of Semi-Stochastic Algorithm for Optimizing Alloy Composition of High-Temperature Austenitic Stainless Steels (H-Series) for Desired

  11. Case study of qualification of remote automated ultrasonic inspection of austenitic pipe weld

    International Nuclear Information System (INIS)

    This paper describes a recent specific example of how Nuclear Electric has demonstrated the capability of a remote automated ultrasonic inspection on its Advanced Gas Cooled Reactor plant. Following the discovery of a small leak in a 300 mm diameter austenitic steam tube there was an urgent requirement to develop a capability for inspecting all similar welds and to provide a demonstration of capability of the inspection. The first part of the paper describes the inspection requirements, the ultrasonic techniques used and the procedure and equipment which was developed. The second part describes how the capability was demonstrated: all the evidence to support the capability was embodied in a technical justification which was prepared under contract by the AEA Technology Inspection Validation Centre (WC). The technical justification included a combination of theoretical evidence and practical evidence from open and blind test block trials together with experience of inspection of other similar components. Within a period of less than two months from initial request, an inspection capability had been developed and justified and was then successfully deployed on-site

  12. Numeric and experimental studies on surface cracking of disks and pipes of ferritic and austenitic steels

    International Nuclear Information System (INIS)

    For safeguarding the transmission chain from the two-dimensional sample to real three-dimensional structural components, the behavior of surface cracks in disks and pipes was investigated in an experimental and a theoretic-numerical way. The objective was a quantitative failure analysis which covers essential phases resulting from operation and breakdown conditions, in fact from the first propagation of the incipient crack under fatigue loading to stabile crack growth under monotonously increasing load up to wall breakthrough and a possible subsequent instability. The investigations of the growth of fatigue cracks show that the growth of partial through-cracks in disks and pipes is generally overestimated in analytic calculations, if the constants of the crack propagation determined for CT samples are used for these calculations. The results presented here show that the J-integral concept is suited to give a good description of the behavior of cracks in constructional components under shear fracture conditions as to the quality and quantity, if the influence of the multi-axiality of the state of stress on the resistance against crack propagation is appropriately considered. The transferability of samples to constructional components seems to be possible for purely mechanical strain even with a superposed amount of bending for a crack propagation which is not too great. (orig.)

  13. Progress in the reliable inspection of cast stainless steel reactor piping components

    International Nuclear Information System (INIS)

    Studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, have focused on assessing the effectiveness and reliability of novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the utility, effectiveness and reliability of ultrasonic testing (UT) and eddy current testing (ET) inspection techniques as related to the inservice ultrasonic inspection of primary piping components in pressurized water reactors (PWRs). This paper describes progress, recent developments and results from assessments of three different NDE approaches including ultrasonic phased array inspection techniques, eddy current testing for surface-breaking flaws, and a low-frequency ultrasonic inspection methodology coupled with a synthetic aperture focusing technique (SAFT). Westinghouse Owner's Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks, PNNL samples containing thermal fatigue cracks and several blank spool pieces were used for assessing the inspection methods. Eddy current studies were conducted on the inner diameter (ID) surface of piping specimens while the ultrasonic inspection methods were applied from the outer diameter (OD) surface of the specimens. The eddy current technique employed a Zetec MIZ-27SI Eddy Current instrument and a Zetec Z0000857-1 cross point spot probe with an operating frequency of 250 kHz. In order to reduce noise effects, degaussing of a subset of the samples resulted in noticeable improvements. The phased array approach was implemented using an R/D Tech Tomoscan III system operating at 1 MHz, providing composite volumetric images of the samples. The low-frequency ultrasonic method employs a zone-focused, multi-incident angle inspection protocol (operating at 250-500 kHz) coupled with SAFT for improved signal-to-noise and

  14. Progress in the Reliable Inspection of Cast Stainless Steel Reactor Piping Components

    International Nuclear Information System (INIS)

    Studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, have focused on assessing the effectiveness and reliability of novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the utility, effectiveness and reliability of ultrasonic testing (UT) and eddy current testing (ET) inspection techniques as related to the inservice ultrasonic inspection of primary piping components in pressurized water reactors (PWRs). This paper describes progress, recent developments and results from assessments of three different NDE approaches including ultrasonic phased array inspection techniques, eddy current testing for surface-breaking flaws, and a low-frequency ultrasonic inspection methodology coupled with a synthetic aperture focusing technique (SAFT). Westinghouse Owner's Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks, PNNL samples containing thermal fatigue cracks and several blank spool pieces were used for assessing the inspection methods. Eddy current studies were conducted on the inner diameter (ID) surface of piping specimens while the ultrasonic inspection methods were applied from the outer diameter (OD) surface of the specimens. The eddy current technique employed a Zetec MIZ-27SI Eddy Current instrument and a Zetec Z0000857-1 cross point spot probe with an operating frequency of 250 kHz. In order to reduce noise effects, degaussing of a subset of the samples resulted in noticeable improvements. The phased array approach was implemented using an R/D Tech Tomoscan III system operating at 1 MHz, providing composite volumetric images of the samples. The low-frequency ultrasonic method employs a zone-focused, multi-incident angle inspection protocol (operating at 250-500 kHz) coupled with SAFT for improved signal-to-noise and

  15. Problematic and metallurgy of welding in the maintenance of the EDF's PWRs. Some applications from the return on experience - Weldability of aged cast austenitic-ferritic stainless steels

    International Nuclear Information System (INIS)

    Peculiar specifications are applied to welding operations during the maintenance of pressurized equipment of EDF's PWR nuclear plants. These specifications can differ from fabrication technical requirements for different reasons: evolution of regulation, taking of material ageing into account and evolution of material weldability characteristics, intervention geometrical conditions, return on experience, impossibility to perform post-welding thermal treatments. Various examples are presented to illustrate these peculiarities: repair of coatings in austenitic stainless steel (either by working or by local welding), multiple assignments of heat-affected-zones, weldability of in-service aged cast austeno-ferritic stainless steels (tests on models)

  16. Experience with one-layer high-strength ferrite and austenite bellous of pipe joint compensators in 20 ata hot steam pipelines

    International Nuclear Information System (INIS)

    Numerous signs of damage have occured on one-layer high-strength ferrite and austenite bellows of pipe joint compensators in 20 ata superheated-steam pipelines. From a precise analysis of the damage cases, it was found that in ferrite material, the high creep-alternating stress lead to damage, whereas in the austenite material, above all the difficult workability and the slight ductility at operational temperature were determining factors. An attempt was made to prolong the lifetime of the compensators equipped with ferrite bellows by increasing the bellow wall thickness from 3 to 4 mm. These new compensators have so far achieved an operational time of about 10,000 hours with 50 drives without visible deformations or damage. (orig./LH)

  17. Leak before break behaviour of austenitic and ferritic pipes containing circumferential defects

    Energy Technology Data Exchange (ETDEWEB)

    Stadtmueller, W.; Sturm, D.

    1997-04-01

    Several research projects carried out at MPA Stuttgart to investigate the Leak-before-Break (LBB) behavior of safety relevant pressure bearing components are summarized. Results presented relate to pipes containing circumferential defects subjected to internal pressure and external bending loading. An overview of the experimentally determined results for ferritic components is presented. For components containing postulated or actual defects, the dependence of the critical loading limit on the defect size is shown in the form of LBB curves. These are determined experimentally and/or by calculation for through-wall slits, and represent the boundary curve between leakage and massive fracture. For surface defects and a given bending moment and internal pressure, no fracture will occur if the length at leakage remains smaller than the critical defect length given by the LBB curve for through-wall defects. The predictive capability of engineering calculational methods are presented by way of example. The investigation programs currently underway, testing techniques, and initial results are outlined.

  18. Impact Strength of Austenitic and Ferritic-Austenitic Cr-Ni Stainless Cast Steel in -40 and +20°C Temperature

    OpenAIRE

    Kalandyk B.; Zapała R.; Boroń Ł.; Solecka M.

    2014-01-01

    Studies described in this paper relate to common grades of cast corrosion resistant Cr-Ni steel with different matrix. The test materials were subjected to heat treatment, which consisted in the solution annealing at 1060°C followed by cooling in water. The conducted investigations, besides the microstructural characteristics of selected cast steel grades, included the evaluation of hardness, toughness (at a temperature of -40 and +20oC) and type of fracture obtained after breaking the specim...

  19. Creep Behavior at 1273 K (1000 °C) in Nb-Bearing Austenitic Heat-Resistant Cast Steels Developed for Exhaust Component Applications

    Science.gov (United States)

    Zhang, Yinhui; Li, Mei; Godlewski, Larry A.; Zindel, Jacob W.; Feng, Qiang

    2016-05-01

    A series of Nb-bearing austenitic heat-resistant cast steels with variations of N/C ratios were investigated, and the morphological change of Nb(C,N) from faceted blocks, mixed flake-blocks to "Chinese-script" was observed as N/C ratios decreased. The creep behavior of these alloys was studied at 1273 K (1000 °C), and the longest creep life and lowest creep rate occurred in model alloys with script Nb(C,N). Residual δ-ferrites and (Cr,Fe)23C6 were adverse to creep properties. This work indicates that the control of N/C ratio is required for the as-cast microstructural strengthening.

  20. Creep Behavior at 1273 K (1000 °C) in Nb-Bearing Austenitic Heat-Resistant Cast Steels Developed for Exhaust Component Applications

    Science.gov (United States)

    Zhang, Yinhui; Li, Mei; Godlewski, Larry A.; Zindel, Jacob W.; Feng, Qiang

    2016-07-01

    A series of Nb-bearing austenitic heat-resistant cast steels with variations of N/C ratios were investigated, and the morphological change of Nb(C,N) from faceted blocks, mixed flake-blocks to "Chinese-script" was observed as N/C ratios decreased. The creep behavior of these alloys was studied at 1273 K (1000 °C), and the longest creep life and lowest creep rate occurred in model alloys with script Nb(C,N). Residual δ-ferrites and (Cr,Fe)23C6 were adverse to creep properties. This work indicates that the control of N/C ratio is required for the as-cast microstructural strengthening.

  1. Microstructure and local strain fields in a high-alloyed austenitic cast steel and a steel-matrix composite material after in situ tensile and cyclic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Weidner, A.; Biermann, H. [Institute of Materials Engineering, Technische Universitaet Bergakademie Freiberg (Germany); Yanina, A.; Guk, S.; Kawalla, R. [Institute of Metal Forming, Technische Universitaet Bergakademie Freiberg (Germany)

    2011-09-15

    The tensile and cyclic deformation behaviour of a new metastable austenitic stainless cast TRIP (TRansformation Induced Plasticity) steel and a composite material consisting of austenitic steel matrix (AISI 304) with 5% MgO partially stabilized ZrO{sub 2} (MgO-PSZ) was studied in-situ in a scanning electron microscope (SEM). In-situ tests in the SEM show the evolution of the microstructure with the strain for uniaxial deformation and the number of cycles during fatigue, respectively. Initially, deformation bands develop. In these bands, the face-centred cubic austenite transforms into the hexagonal {epsilon}-martensite and subsequently to the body-centred cubic {alpha}'- martensite. This evolution was studied by different SEM techniques. Electron backscatter diffraction (EBSD) was applied for phase and orientation identification. The dislocation arrangement was investigated applying the electron channelling contrast imaging (ECCI) technique to different deformation stages. The studies are completed with measurements of local displacement fields using digital image correlation (DIC). (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Effect of Tempering and Strain on Decomposition of Metastable Austenite in X210CrW12 Thixo-Cast Steel

    Science.gov (United States)

    Rogal, Ł.; Bonarski, J. T.; Bobrowski, P.

    2016-03-01

    Thixoforming of hot rolled X210CrW12tool steel led to the formation of globular austenitic grains (82.4 vol.%) surrounded by eutectic mixture (α-Fe and M7C3 carbides). The thixo-cast steel reached compression strength 4.8 GPa at plastic strain 34%. The analysis of pole figures after deformation indicated distinct texturization of microstructure in comparison with undeformed steel. Main texture components for austenite were {101}, , while ferrite did not reveal clearly formed orientation. DSC analysis confirmed that austenitic structure in the X210CrW12 steel was metastable and temperature of decomposition depended on the strain applied at 634 °C for the un-deformed sample and at 599 °C for sample compressed up to 4.8 GPa. Discontinuous transformation of austenite into perlite, that started mainly at grain boundaries and proceeded to the center, was the predominant mechanism responsible for the decomposition of globular grains in thixoformed X210CrW12 steel. The decomposition caused by tempering of supersaturated and severely strained steel led to obtaining characteristic product of transformation of higher hardness in comparison with only tempered sample. In the deformed sample the reaction started on slip bands and twins which revealed high density of defects, promoting precipitation of carbides, followed by local depletion in carbon as a result of α'- Fe formation. In contrast to non-deformed state they covered the area of grains. Two fronts of reaction α-Fe plate +M3C → mixture of α-Fe and M7C3 carbides were also observed.

  3. A study of austenitization of SG iron

    Indian Academy of Sciences (India)

    Uma Batra; Pankaj Tandon; Kulbir Kaur

    2000-10-01

    Austenitization process of three SG irons with varying compositions and as cast matrix microstructure has been studied at three austenitization temperatures of 850, 900 and 950C for different time periods. Microstructure, hardness and X-ray diffraction have been used to reveal the nature of dependence of the process on austenitization temperature, time and as cast structure. The optimum austenitization time is maximum for ferritic and minimum for pearlitic matrix.

  4. Review of environmental effects on fatigue crack growth of austenitic stainless steels

    International Nuclear Information System (INIS)

    Fatigue and environmentally assisted cracking of piping, pressure vessel cladding, and core components in light water reactors are potential concerns to the nuclear industry and regulatory agencies. The degradation processes include intergranular stress corrosion cracking of austenitic stainless steel (SS) piping in boiling water reactors (BWRs), and propagation of fatigue or stress corrosion cracks (which initiate in sensitized SS cladding) into low-alloy ferritic steels in BWR pressure vessels. Crack growth data for wrought and cast austenitic SSs in simulated BWR water, developed at Argonne National Laboratory under US Nuclear Regulatory Commission sponsorship over the past 10 years, have been compiled into a data base along with similar data obtained from the open literature. The data were analyzed to develop corrosion-fatigue curves for austenitic SSs in aqueous environments corresponding to normal BWR water chemistries, for BWRs that add hydrogen to the feedwater, and for pressurized water reactor primary-system-coolant chemistry

  5. Detection and sizing of large-scale cracks in centrifugally cast stainless steel pipes using Lamb waves

    International Nuclear Information System (INIS)

    Application of conventional ultrasonic nondestructive evaluation (NDE) techniques to centrifugally cast stainless steel (CCSS) pipes in pressurized water reactors (PWRs) has been limited, mainly due to the anisotropy of the CCSS materials. Phenomena such as beam skewing and distortion are directly attributable to this anisotropy and cause severe difficulties in crack detection and sizing. To improve CCSS inspectability, the feasibility of using Lamb waves as the probing mechanism for detecting and characterizing a surface-breaking crack originating from the pipe interior surface is discussed. A similar research effort has been reported by Rokhlin who investigated the interaction of Lamb waves with delaminations in thin sheets. Rokhlin and Adler also reported recently on the use of Lamb waves for evaluating spot welds. The motivation for using this probing mechanism derives from the recognition that the difficulties introduced by beam skewing, beam distortion, and high attenuation are circumvented, since Lamb waves are not bulk waves, but are resonant vibrational modes of a solid plate

  6. Concept for the monitoring of weld seams on pressure pipes made of austenitic steel using ultrasonic processes

    International Nuclear Information System (INIS)

    A concept for the repeat testing of weld seams in pipelines made of Austenitic steel using ultrasonic processes is developed and tested. Even with varying sound attenuation in the material and on the occurence of 'ghost' indications, it ensures certain indication of faults. Further, the depth of cracks can be assessed, for example by the height of echos, even for large extents. (orig.)

  7. Plastic fracture toughness of austenitic welding connection for Ver-1000 nuclear reactor piping of 300-350 mm diameter

    International Nuclear Information System (INIS)

    The outside welding technology for circular welds in a pearlitic tube using austenitic welding wire materials is developed and applied in manufacturing pipelines of CPP and ECC. Mechanical properties and fracture toughness of austenitic welded joints in pearlitic tubes are determined to substantiate by calculation the practicality of the leakage prior to failure concept. The work is accomplished on experimental tube manufactured by hand arc welding. When manufactured the tube is cut into 5 rings. From the rings the tensile specimens are cut for testing at 20 and 350 deg C as well as Charpy V-notch impact specimens and compact specimens ST-1T. It is shown that the materials of the experimental tube meet the standard requirements. Only axial specimens cut across the weld are not in conformity with the requirements for specific elongation

  8. Characterisation of the fatigue properties of cast irons used in the water industry and the effect on pipe strength and performance

    International Nuclear Information System (INIS)

    As part of an on going programme to characterise the residual properties and understand the failure mechanisms of in-service grey cast iron water pipes, the fatigue crack propagation behaviour of grey cast iron samples has been studied. Specimens were sourced from three ex-service pipes. For each pipe the microstructure and composition were characterised and the fracture toughness was determined. The fatigue behaviour was investigated in terms of the crack growth rate (da/dN) as a function of the applied stress intensity factor range. Clear differences in the fatigue behaviour of the samples from different pipes were observed. The result from these investigations, which indicate that microstructural differences play a role in mechanical behaviour, will support the development of asset management tools for use in the water industry.

  9. An evaluation of depth sizing ability of ultrasonic testing by the large aperture transducer for axial crack in cast stainless steel pipe weld

    International Nuclear Information System (INIS)

    Ultrasonic testing is difficult for cast stainless steel which is used as the material of main coolant pipes in pressurized water reactors, because of the large attenuation and scattering of ultrasonic waves caused by its macro structure. Ultrasonic testing for the axial fatigue crack on welding area in the test piece of the cast stainless pipe was performed, using the double large aperture ultrasonic probes. In this study, depth sizing of defects was performed under the positive result of the detection of defects in former study. As a result, sizing of defects with over 20mm target depth for the specimen thickness 69mm is highly possible. (author)

  10. Simulation and control of the cyclic damage of the NPP pipe made of austenite steel after long-term service

    International Nuclear Information System (INIS)

    Simulation of the cyclic damage of austenite steel 12Kh18N10T and simultaneous control and study of the metal structure using nondestructive methods were performed. The metal was studied at the initial stage and at different stages of aging according to the low-cycle fatigue mechanism. The local magnetic method thus used is highly informative and the results obtained correspond to the character of changes in the cyclic strength properties of steel 12Kh18N10T. The structure study revealed that structure change attributed to plastic deformation at different stages of cyclic damage correlates with the magnetic signal

  11. Cast heat-resistant austenitic steel with improved temperature creep properties and balanced alloying element additions and methodology for development of the same

    Science.gov (United States)

    Pankiw, Roman I; Muralidharan, Govindrarajan; Sikka, Vinod Kumar; Maziasz, Philip J

    2012-11-27

    The present invention addresses the need for new austenitic steel compositions with higher creep strength and higher upper temperatures. The new austenitic steel compositions retain desirable phases, such as austenite, M.sub.23C.sub.6, and MC in its microstructure to higher temperatures. The present invention also discloses a methodology for the development of new austenitic steel compositions with higher creep strength and higher upper temperatures.

  12. Fracture mechanics evaluation for at typical PWR primary coolant pipe

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, T. [Kansai Electric Power Company, Osaka (Japan); Shimizu, S.; Ogata, Y. [Mitsubishi Heavy Industries, Ltd., Kobe (Japan)

    1997-04-01

    For the primary coolant piping of PWRs in Japan, cast duplex stainless steel which is excellent in terms of strength, corrosion resistance, and weldability has conventionally been used. The cast duplex stainless steel contains the ferrite phase in the austenite matrix and thermal aging after long term service is known to change its material characteristics. It is considered appropriate to apply the methodology of elastic plastic fracture mechanics for an evaluation of the integrity of the primary coolant piping after thermal aging. Therefore we evaluated the integrity of the primary coolant piping for an initial PWR plant in Japan by means of elastic plastic fracture mechanics. The evaluation results show that the crack will not grow into an unstable fracture and the integrity of the piping will be secured, even when such through wall crack length is assumed to equal the fatigue crack growth length for a service period of up to 60 years.

  13. Elimination of casting heterogeneities by high temperature heat treatment on a titanium stabilized austenitic alloy. Effect on the microstructure

    International Nuclear Information System (INIS)

    Microstructural observation on a longitudinal section of stainless steels often reveals the presence of a ''veined'' structure showing a segregation remainder due to the setting of the ingot. This casting heterogeneity can be eliminated by high temperature treatments. This study shows the change in the structure and the state of solubilization produced by these high temperature treatments and the effect of a stabilizing element such as titanium on Z6CNDT17.13 and Z10CNDT15.15B alloys compared with the Z6CND17.13 alloy. It is also shown that a high temperature treatment applied to these stabilized alloys deeply modifies the recrystallization kinetics

  14. Transmission electron microscopy study of cast duplex austenitic stainless steels with varying ferrite content: as-cast and deformed at 4 K

    International Nuclear Information System (INIS)

    The evolution of dislocation substructure and residual delta morphology in the as-cast state was studied by transmission electron microscopy and selected area electron diffraction in a series of CF8M alloys with varying ferrite content. Results were correlated with a previous light microscopy study. A well recovered dislocation substructure existed in both phases and was correlated with the delta → γ transformation and thermal history. The lattice correspondence observed by electron diffraction and habit planes of facets in the delta/γ interfacial morphology were consistent with a model based on a semicoherent interface. All results were consistent with a proposed model for evolution of residual delta morphology analogous to the proeutectoid γ → α transformation. The evolution of substructure was detailed in 17.2 volume percent and 28.5 volume percent alloys that were strained at 4 K. Low strain specimens were characterized by dislocation generation in both phases in the vicinity of the delta/γ interface, dislocation-dislocation interactions and dislocation-sub-boundary interactions in γ. Later stages displayed formation and intersection of shear/deformation bands in γ and was followed by α' formation at the intersections. Bands of dislocations formed in the delta followed by deformation twinning in that phase. The results of γ deformation were considered in light of current theories of the strain-induced γ → α' transformation and work hardening in metastable γ in addition to theories regarding plastically non-homogeneous alloys

  15. Comparative analysis of the behavior to corrosion of forged and cast austenitic stainless steel when used in a surgical prosthesis

    International Nuclear Information System (INIS)

    The selection of a material to be used in implants involves tests that cover aspects relative to its resistance to corrosion and its bio-compatibility. Testing the material implanted in the human body is a very difficult process or it is impossible via direct electrochemistry. Because of this laboratory tests have been developed that simulate the natural setting of the material in the organism using saline solutions that are kept at 37oC and pH 7.4. The material that is to be used should be resistant to corrosion in the body so that ions are not released into the organism and the device should maintain its integrity in service and not to suffer degradation. This work compares the behavior to corrosion of samples of a cast prosthesis (lower tibia, made of stainless steel ACI CF 3M) and a forged prosthesis (femorals, made of stainless steel ASTM F 621) with laminated bars of the same quality (stainless steel ASTM F 138). The samples were characterized with physical and electrochemical tests under three different thermal conditions: solubilized, annealed and forged or cast. The test pieces were submitted to electrochemical direct current tests during their immersion in a 0.9% deoxygenated NaCl solution and thermostatisized at 37oC. The Cr and Fe content in solution at the end of the electrochemical test was evaluated together with the micro hardness of the material and the characterization of the final stage of the material was carried out by optic microscopy and sweep electronics (CW)

  16. Carbon Concentration of Austenite

    Directory of Open Access Journals (Sweden)

    Z. Ławrynowicz

    2007-07-01

    Full Text Available The investigation was carried out to examine the influence of temperature and times of austempering process on the maximum extend towhich the bainite reaction can proceed and the carbon content in retained austenite. It should be noted that a small percentage change in theaustenite carbon content can have a significant effect on the subsequent austempering reaction changing the volume fraction of the phasespresent and hence, the resulting mechanical properties. Specimens were prepared from an unalloyed ductile cast iron, austenitised at 950oCfor 60 minutes and austempered by the conventional single-step austempering process at four temperatures between BS and MS, eg., 250,300, 350 and 400oC. The samples were austempered at these temperatures for 15, 30, 60, 120 and 240 minutes and finally quenched toambient temperature. Volume fractions of retained austenite and carbon concentration in the residual austenite have been observed byusing X-ray diffraction. Additionally, carbon concentration in the residual austenite was calculated using volume fraction data of austeniteand a model developed by Bhadeshia based on the McLellan and Dunn quasi-chemical thermodynamic model. The comparison ofexperimental data with the T0, T0' and Ae3' phase boundaries suggests the likely mechanism of bainite reaction in cast iron is displacive rather than diffusional. The carbon concentration in retained austenite demonstrates that at the end of bainite reaction the microstructure must consist of not only ausferrite but additionally precipitated carbides.

  17. Environmentally assisted cracking and irradiation embrittlement of CF-8 and CF-8M cast austenitic stainless steels in high-purity water

    International Nuclear Information System (INIS)

    Cast austenitic stainless steels (CASS) are used for components with complex geometries in the cooling system of light water reactors (LWRs). Due to both thermal ageing and irradiation embrittlement, the long-term performance of CASS materials is of concern. To assess the impact of thermal ageing and irradiation embrittlement on the cracking behaviour of CASS materials, crack growth rate and fracture toughness JR curve tests were carried out on CF-8 and CF-8M compact-tension specimens in high-purity water with low dissolved oxygen. The as-received and thermally aged CASS specimens were irradiated to 0.08 dpa to investigate the combined effect of thermal ageing and neutron irradiation. The crack growth rates of irradiated CASS materials were compared with previous results on unirradiated specimens. While no elevated cracking susceptibility was observed for the irradiated specimens at this dose level, a slightly better corrosion fatigue performance was found in the CF-8 than in CF-8M materials. Thermal ageing history had little effect on the crack growth behaviour in the test environment. Trans-granular cleavage-like cracking was the main fracture mode in the crack growth rate tests, and delta ferrite morphology could be seen in some areas on the fracture surfaces. Compared to thermal ageing, neutron irradiation had a dominant role in the fracture toughness JR curve tests. The loss of toughness due to neutron irradiation was much more significant in the as-received than in the thermally aged CASS specimens. The fracture toughness of CASS specimens was reduced to a similar level after neutron irradiation regardless of their thermal ageing history. This suggests a more rapid development of embrittlement in the as-received than in the thermally aged CASS specimens under neutron irradiation. (authors)

  18. Ultrasonic testing of austenitic stainless steel welds

    International Nuclear Information System (INIS)

    Ultrasonic testing of austenitic stainless steel welds has been considered difficult because of the high noise level and remarkable attenuation of ultrasonic waves. To improve flaw detectability in this kind of steel, various inspection techniques have been studied. A series of tests indicated: (1) The longitudinal angle beam transducers newly developed during this study can detect 4.8 mm dia. side drilled holes in dissimilar metal welds (refraction angle: 550 from SUS side, 450 from CS side) and in cast stainless steel welds (refraction angle: 450, inspection frequency: 1 MHz). (2) Cracks more than 5% t in depth in the heat affected zones of fine-grain stainless steel pipe welds can be detected by the 450 shear wave angle beam method (inspection frequency: 2 MHz). (3) The pattern recognition method using frequency analysis technology was presumed useful for discriminating crack signals from spurious echoes. (author)

  19. Ultrasonic wave propagation considerations for centrifugally cast stainless steel pipe inspection

    International Nuclear Information System (INIS)

    This paper reports on an investigation of the ultrasonic wave propagation in centrifugally cast stainless steel (CCSS). CCSS can have an anisotropic grain structure which affects the ultrasonic wave propagation. Such parameters as wave velocity, attenuation, beam deviation, and beam scattering are also affected. An understanding of the grain structure influences on the wave propagation is necessary before compensation can be made to improve examination effectiveness. During the investigations, the grain effects on wave propagation were investigated, and an ultrasonic technique for grain structure identification was developed

  20. An evaluation of detection ability of ultrasonic testing with a large aperture transducer for axial cracks in cast stainless steel pipe welds

    International Nuclear Information System (INIS)

    Ultrasonic testing is difficult to apply to cast stainless steel which is the material of the main coolant pipes in pressurized water reactors, because of the large attenuation and scattering of ultrasonic waves caused by its macro structure. In this study, ultrasonic testing for progression of axial fatigue cracks of a welded area in the test piece of cast stainless steel pipe was performed using double big-size ultrasonic probes which were formerly developed in INSS. It was found that detection of defects that were over 6% of the target depth for the specimen thickness of 69mm is possible, and detection of defects with over 10% of the target depth is possible for all test conditions. (author)

  1. Performance evaluation of cast iron pipe for crude oil and salt water transportation; Avaliacao e desempenho de duto de aco fundido no transporte de petroleo com aguas salgadas

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Carlos Alexandre Martins da [PETROBRAS Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil); Mainier, Fernando B. [Universidade Federal Fluminense, Niteroi, RJ (Brazil)

    2005-07-01

    The present paper aims to study and to evaluate the performance of casting iron pipe for transportation of salty and produced waters, presented in the oil industry, where salt contents ranging on very large values. The cast iron above mentioned has an yield strength of 23 kg/mm{sup 2}, tensile strength of de 46 kg/mm{sup 2} (minimum) and an elongation of 15%, and contents of some chemical alloys, such as Cr (0,8 -1,3 %), Mn (1,5 % max) and Si (1,%). Nevertheless it is an exploratory study, the dynamic tests of weight loss carried out in laboratory, with specimens machined from a used pipe piece, with salty solution (3,5 % NaCl) aerated media, has shown very promising results, enabling to qualify, satisfactorily, such material for using in transportation and transferring operations of fluids with a high salty contents, such as crude oil. (author)

  2. Development of the ultrasonic technique for examination of centrifugally-cast stainless steel in pressure piping

    International Nuclear Information System (INIS)

    Centrifugally - cast stainless steel (CCSS) are used to manufacture a large variety of components in the nuclear industry. Weldments are also made to join these parts to carbon steel items. These welds are usually made of stainless steel or inconel alloys. CCSS is sophisticated material and justification for its use in critical components is safety and reliability. These steels, as any other materials, need to be inspected to assess their structural integrity. Ultrasonic testing is one of the possible techniques. In some cases it is the only one of the feasible methods for this examination. This mainly concerns components in the primary and auxiliary circuits of nuclear plants. For a long time it has been recognized that CCSS items can be extremely difficult to inspect using ultrasonics. Many attempts in various research laboratories were conducted to improve the testing technique

  3. Cast pipe joints of Fe-15Mn-5Si-8Cr-5Ni-0.25C shape memory alloy with high carbon content

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, M.; Li, J.C.; Jiang, Q. [Department of Materials Science and Engineering, Jilin University at Nanling Campus, Renmin Street 142, Changchun 130025 (China)

    2003-08-01

    The cast pipe joint of the Fe-15Mn-5Si-8Cr-5Ni-0.25C alloy was manufactured (the numbers in the composition denote the weight percentage of the elements while the weight percentage of Fe is the balance). The corresponding microstructure and shape memory effect are compared with those of a forged alloy. The results show that the cast joint has a good shape memory effect and may be industrially applied while the cast joint keeps jointing under a tensile force of 20 kN and a sealing pressure of 5 MPa. Moreover, it is found that the addition of nitrogen in the alloy doesn't evidently improve the shape memory effect of the alloy. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  4. Evaluation of the degradation characteristics of CF-8A cast stainless steel using EDS and nano-indentation

    International Nuclear Information System (INIS)

    Cast austenitic stainless steel piping pump, valve casings, and elbows are susceptible to reductions in toughness and ductility because of long term exposure at the operating temperatures in LWR(Light Water Reactor). In this paper, we have measured the material properties of long term aged CF-8A cast stainless steel, accelerated aging at 400 .deg. C. These studies have been carried out using indentation tests(automated ball indentation and nano-indentation) and EDS(Energy Dispersive Spectroscopy). The fracture toughness of Cf-8A cast stainless steel was also determined by using standard fracture toughness and automated ball indentation

  5. Some characteristics properties of structure of stainless steel pipe blanks produced by vacuum centrifugal casting for nuclear power

    International Nuclear Information System (INIS)

    Results of studies macro- and microstructures of centrifugal castings and distributions of inclusions and alloying elements and impurities are presented. It was established that distribution of components of steels in castings is uniform. The macro structure is band and the microstructure is dendritic. Principal feature of centrifugal castings is redistribution of inclusions, main part of casting being free from conclusions. 1 refs.; 4 figs.; 3 tabs. (author)

  6. Progress report on a NDT round robin on austenitic circumferential pipe welds; Fortschrittsbericht ueber einen ZfP-Ringversuch an austenitischen Rohrleitungs-Rundschweissnaehten

    Energy Technology Data Exchange (ETDEWEB)

    Brast, G. [Preussische Elektrizitaets-AG (Preussenelektra), Hannover (Germany); Maier, H.J.; Knoch, P.; Mletzko, U. [Stuttgart Univ. (Germany). Staatliche Materialpruefungsanstalt

    1998-11-01

    The objective of the project is establish on the basis of Round Robin tests the current state of efficiency of various, defined testing methods, so that required or achievable optimizations can be defined and made. The project work up to date encompasses mon-destructive examinations of 15 austenitic welds with nominal widths DN 150/200/250 and wall thicknesses from 8 to 18 mm. Except for one test piece, (elbow/elbow), the joining welds are straight pipe to elbow welds. The results of the Round Robin tests show that the NDE detection limits for the fault examined (intercrystalline stress corrosion cracking) are in the range assumed so far, i.e. from about 20 to 25% of the wall thickness to be examined. The defect detection rates of the ultrasonic test methods applied are approx. 70% and thus are about equal in achievement with comparable international Round Robin tests (PISC; ASME/PDI, ENIQ, etc.). Clearly better are the fault detection rates of radiography. Evaluation of the individual results indicates the detection limits can be improved, by 1. reducing the misalignment of edges, 2. grinding of welds, 3. avoiding sharp notches at the root, 4. producing coaxial surfaces. (orig./CB) [Deutsch] Ein Ziel des Vorhabens ist es, mit Ringversuchen den derzeitigen Stand der Leistungsfaehigkeit einzelner Pruefverfahren und -techniken zu erkennen, um moeglicherweise notwendige Optimierungen vornehmen zu koennen. Das Vorhaben umfasst bis jetzt zerstoerungsfreie Pruefungen an 15 austenitischen Naehten mit Nennweiten DN 150/200/250 und Wandstaerken zwischen 8 und 18 mm. Mit einer Ausnahme (Bogen/Bogen) handelt es sich um Verbindungen Geradrohr/Bogen. Die Ergebnisse des Ringversuches weisen darauf hin, dass die Nachweisgrenzen der ZfP fuer den vorliegenden Fehlertyp (Interkristalline Spannungsrisskorrosion) in der bisher schon angenommenen Groessenordnung von ca. 20-25% der geprueften Wanddicke liegen. Die Fehlerauffind-Raten der US-Pruefung liegen mit ca. 70% im Rahmen

  7. 铸钢件与无缝钢管焊接技术%Cast Steel and Seamless Steel Pipe Welding Technology

    Institute of Scientific and Technical Information of China (English)

    臧盐龙

    2012-01-01

    结合京沪高速铁路镇江南站站房工程铸钢件同无缝钢管焊接施工中一些技术工作及相关经验,通过设计院的相关设计文件及现场焊接工艺的指导,经过权威专家的评审,最终根据焊接的成果总结出了在管桁架结构的现场安装中铸钢件同无缝钢管的焊接工艺及注意要点。%In combination with the steel castings with seamless steel pipe welding construction technology and related work experience of Beijing-Shanghai High Speed Railway Zhenjiang south railway station building engineering, through the design of the related design documents and field welding process guidance, through the assessment of experts, based on the final welding results, the paper summarized steel castings with seamless steel pipe welding process and points for attention in pipe truss structure installation.

  8. Bainite obtaining in cast iron with carbides castings

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2010-01-01

    Full Text Available In these paper the possibility of upper and lower bainite obtaining in cast iron with carbides castings are presented. Conditions, when in cast iron with carbides castings during continuous free air cooling austenite transformation to upper bainite or its mixture with lower bainte proceeds, have been given. A mechanism of this transformation has been given, Si, Ni, Mn and Mo distribution in the eutectic cell has been tested and hardness of tested castings has been determined.

  9. Probability of pipe fracture in the primary coolant loop of a PWR plant. Volume 5: probabilistic fracture mechanics analysis. Final report

    International Nuclear Information System (INIS)

    The purpose of the portion of the Load Combination Program covered in this volume was to estimate the probability of a seismic induced loss-of-coolant accident (LOCA) in the primary piping of a commercial pressurized water reactor (PWR). Such results are useful in rationally assessing the need to design reactor primary piping systems for the simultaneous occurrence of these two potentially high stress events. The primary piping system at Zion I was selected for analysis. Attention was focussed on the girth butt welds in the hot leg, cold leg and cross-over leg, which are centrifugally cast austenitic stainless steel lines with nominal outside diameters of 32 - 37 inches

  10. The heat treatment of Fermanal cast steel

    OpenAIRE

    F. Binczyk; A. Smoliński; J. Szymszal

    2007-01-01

    The study discloses the results of microstructural examinations, testing of magnetic properties and hardness measurements as cast and after heat treatment conducted on the Fermanal cast steel. A characteristic feature of this cast steel is its density lower by about 10% than the density of carbon cast steel [4]. It has been proved that the factor deciding about the composition of microstructure (fraction of ferrite and austenite) is the content of aluminium. The matrix totally austenitic is p...

  11. Characteristics of Friction Welding Between Solid Bar of 6061 Al Alloy and Pipe of Al-Si12CuNi Al Cast Alloy

    Science.gov (United States)

    Kimura, M.; Sakaguchi, H.; Kusaka, M.; Kaizu, K.; Takahashi, T.

    2015-11-01

    This paper describes the characteristics of friction welding between a solid bar of 6061 Al alloy and a pipe of Al-Si12CuNi (AC8A) Al cast alloy. When the joint was made by a continuous drive friction welding machine (conventional method), the AC8A portion of the joint showed heavy deformation and the AA6061 showed minimal deformation. In particular, the joint could not be successfully made with following conditions, because AC8A pipe side crushed due to insufficient friction heat or high pressure: a short friction time such as 0.3 s, high friction pressure such as 100 MPa, or high forge pressure such as 150 MPa. The heavy deformation of AC8A side was caused by increasing friction torque during braking. To prevent braking deformation until rotation stops, a joint was made by a continuous drive friction welding machine that has an electromagnetic clutch. When the clutch was released, the relative speed between both specimens simultaneously decreased to zero. When the joint was made with friction pressure of 25 MPa, friction time of 0.3 s, and forge pressure of 125 MPa, the joining could be successfully achieved and that had approximately 16% efficiency. In addition, when the joint was made with friction pressure of 25 MPa, friction time of 0.7 s, and forge pressure of 125 MPa, it had approximately 54% efficiency. However, all joints showed the fracture between the traveled weld interface and the AC8A side, because the weld interface traveled in the longitudinal direction of AC8A side from the first contacted position of both weld faying surfaces. Hence, it was clarified that the friction welding between a solid bar of AA6061 and a cast pipe of AC8A was not desirable since the traveling phenomena of the weld interface were caused by the combination of the shapes of the friction welding specimens.

  12. Statistical laws of IGSCC of welded joints in the austenitic Du-300 piping of the multiple forced circulation circuit of the RBMK reactors

    International Nuclear Information System (INIS)

    The process of intergranular corrosion stress cracking is analyzed for welded joints of Du-300 austenitic pipelines of multiple forced circulation circuit of the RBMK reactor. Statistical estimates of parameters determining the service life of pipelines are obtained. The calculation procedure is developed for residual lifetime of Du-300 pipeline welded joints with taking into account the scatter in the data on critical degree of sensitization and crack growth rates

  13. Evidence of cracks in austenitic pipe weldings with a radiometric inspection system; Nachweis von Rissen in austenitischen Rohrleitungsnaehten mit einem radiometrischen Pruefsystem

    Energy Technology Data Exchange (ETDEWEB)

    Maier, H.J.; Wuensch, W. [Stuttgart Univ. (Germany). Staatliche Materialpruefungsanstalt

    1999-08-01

    The paper reports the development of a radiometric prototype device and its application to inspection of austenitic weldings with intercrystalline crack defects. The device initially was intended to be used for supplemental inspection for clarification of contradictory or unclear testing results, but the results obtained justify to consider the possibility of using it as an independent, full-scope testing instrument. (orig./CB) [Deutsch] Berichtet wird ueber die Entwicklung eines Prototypes eines Radiometrie-Geraetes zur Pruefung von austenitischen Schweissnaehten mit interkristalliner Rissbildung, zunaechst als Entscheidungshilfe bei unklaren bzw. sich widersprechenden Pruefresultaten. Zwischenzeitlich wird auch daran gedacht, ein solches Geraet fuer eine vollstaendige Pruefung weiter zu entwickeln. (orig./DGE)

  14. Metal properties of centrifugal cast pipes of 15Kh1M1F and 15 GS steels

    International Nuclear Information System (INIS)

    In the present work the properties of the parent metla of experimental-industrial batches of centrifugally-cast tubes of 15Cr1Mo1V and 15MnSi (16MnSi) steel are investigated. The specimens were tested for creep and rupture strength; the macro- and microstructures of a large number of sections were studied. The tubes were carefully tested ultrasonically with the aid of a UDM1F flaw detector. A characteristic of the tube metal was the fairly dense structure. The results obtained showed that it is possible to use centrifugally-cast tubes, but that it is necessary to carry out improvement work and to ensure stability of the cycle of fabrication and treatment of the tubes

  15. Effect of micro segregation on pitting corrosion of SCS 14 austenitic stainless steel castings in sea water environments; SCS 14 osutenaitokei sutenresuchuko no kaisuichu deno koshoku kyodo ni oyobosu mikuro henseki no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Tomoya. [Hitachi Ltd., Tokyo (Japan). Hitachi Research Laboratory; Yokosuka, Tsunenobu. [Hitachi Kyowa Engineering Ltd., Ibaraki (Japan); Honda, Takashi. [Hitachi Nuclear Engineering Ltd., Ibaraki (Japan)

    1999-06-15

    Austenitic stainless steel castings, such as SCS 13, SCS 14, which consists of {delta}/{gamma} duplex phase, are extensively used as structural material in seawater environments. It is known that SCS 14 involving 2wt% Mo is more resistant to pitting corrosion than SCS 13. In this paper, effects of Mo on the pitting corrosion are discussed in terms of microstructure of the material. The corrosion behavior of the materials with different {delta} ferrite contents and cleanlinesses have been evaluated by seawater exposure testing, electrochemical polarization, and TEM-EDX analysis. The results indicate that pits mainly nucleate at nonmetallic inclusions such as MnS and {delta}/{gamma} boundaries, and materials containing {delta} ferrite above 7vol% have high pitting corrosion resistance. The nucleation at {delta}/{gamma} boundaries is assumed to be due to the segregation of P. It is considered that because of segregation of Mo along {delta}/{gamma} boundaries, SCS 14 is much resistant to pitting corrosion than SCS 13. (author)

  16. Numerical modelling of solidification of thin walled hypereutectic ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Hattel, Jesper; Tiedje, Niels

    2006-01-01

    the presence of austenite dendrites even in hypereutectic castings. In thin-walled castings the presence of austenite dendrites is even more pronounced, which increases the risk of shrinkage porosities. This off-eutectic austenite is therefore an important part that should be taken into account during...

  17. Influence of Thermal Aging on Primary Water Stress Corrosion Cracking of Cast Duplex Stainless Steels

    International Nuclear Information System (INIS)

    In order to evaluate the SCC (stress corrosion cracking) susceptibility of cast duplex stainless steels which are used for the main coolant piping material of pressurized water reactors (PWRs), the slow strain rate test (SSRT) and the constant load test (CLT) were performed in simulated PWR primary water at 360 C. The main coolant piping materials contain ferrite phase with ranging from 8 to 23 % and its mechanical properties are affected by long time thermal aging. The 23% ferrite material was prepared for test as the maximum ferrite content of main coolant pipes in Japanese PWRs. The brittle fracture in the non-aged materials after SSRT is mainly caused by quasi-cleavage fracture in austenitic phase. On the other hand, a mixture of quasi-cleavage fracture in austenite and ferrite phases was observed on long time aged material. Also on CLT, (2 times σy), after 3,000 hours exposure, microcracks were observed on the surface of non-aged and aged for 10,000 hours at 400 C materials. The crack initiation site of CLT is similar to that of SSRT. The SCC susceptibility of the materials increases with aging time. It is suggested that the ferrite hardening with aging affect SCC susceptibility of cast duplex stainless steels. (authors)

  18. Austenitic stainless steels for cryogenic service

    Energy Technology Data Exchange (ETDEWEB)

    Dalder, E.N.C.; Juhas, M.C.

    1985-09-19

    Presently available information on austenitic Fe-Cr-Ni stainless steel plate, welds, and castings for service below 77 K are reviewed with the intent (1) of developing systematic relationships between mechanical properties, composition, microstructure, and processing, and (2) of assessing the adequacy of these data bases in the design, fabrication, and operation of engineering systems at 4 K.

  19. Austenitic stainless steels for cryogenic service

    International Nuclear Information System (INIS)

    Presently available information on austenitic Fe-Cr-Ni stainless steel plate, welds, and castings for service below 77 K are reviewed with the intent (1) of developing systematic relationships between mechanical properties, composition, microstructure, and processing, and (2) of assessing the adequacy of these data bases in the design, fabrication, and operation of engineering systems at 4 K

  20. Development of ultrasonic testing techniques for welding parts of austenitic stainless. Part 2. Development of ultrasonic testing system and numerical analysis of wave propagation for field pipes

    International Nuclear Information System (INIS)

    An automatic ultrasonic testing system is developed for circumferential seam-weld inspection of pipes, in which not only advanced phased array and TOFD methods but also other conventional methods are applicable. Various specimens with slit or stress corrosion crack are used to verify the system. The verification shows (1) the detectability of the system is 100% and (2) the error between actual height and the measured is smaller than 4.4 mm, namely the system has sufficient precision. However, due to the effect of scattering at the boundaries of large crystal grains, receiving diffracted waves from crack tips is difficult. FEM analysis of wave propagation considering crystal grains is performed to investigate this effect. Numerical results show that attenuation coefficient increases and the central frequency of back echo decreases with increment in grain size, which is in good agreement with experimental ones. (author)

  1. Effects of microbial redox cycling of iron on cast iron pipe corrosion in drinking water distribution systems.

    Science.gov (United States)

    Wang, Haibo; Hu, Chun; Zhang, Lili; Li, Xiaoxiao; Zhang, Yu; Yang, Min

    2014-11-15

    Bacterial characteristics in corrosion products and their effect on the formation of dense corrosion scales on cast iron coupons were studied in drinking water, with sterile water acting as a reference. The corrosion process and corrosion scales were characterized by electrochemical and physico-chemical measurements. The results indicated that the corrosion was more rapidly inhibited and iron release was lower due to formation of more dense protective corrosion scales in drinking water than in sterile water. The microbial community and denitrifying functional genes were analyzed by pyrosequencing and quantitative polymerase chain reactions (qPCR), respectively. Principal component analysis (PCA) showed that the bacteria in corrosion products played an important role in the corrosion process in drinking water. Nitrate-reducing bacteria (NRB) Acidovorax and Hydrogenophaga enhanced iron corrosion before 6 days. After 20 days, the dominant bacteria became NRB Dechloromonas (40.08%) with the protective corrosion layer formation. The Dechloromonas exhibited the stronger corrosion inhibition by inducing the redox cycling of iron, to enhance the precipitation of iron oxides and formation of Fe3O4. Subsequently, other minor bacteria appeared in the corrosion scales, including iron-respiring bacteria and Rhizobium which captured iron by the produced siderophores, having a weaker corrosion-inhibition effect. Therefore, the microbially-driven redox cycling of iron with associated microbial capture of iron caused more compact corrosion scales formation and lower iron release. PMID:25150521

  2. Mechanized radiation testing of austenitic pipe welds. Testing of media filled pipes and determination of the flaw depth by tomosynthesis; Mechanisierte Durchstrahlungspruefung von Rundschweissnaehten. Pruefung mediengefuellter Rohrleitungen und Tiefenlagenbestimmung durch Tomosynthese

    Energy Technology Data Exchange (ETDEWEB)

    Ewert, U.; Redmer, B. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany); Mueller, J. [COMPRA GmbH, Frechen (Germany); Trobitz, M. [Kernkraftwerke Gundremmingen Betriebsgesellschaft mbH, Gundremmingen (Germany); Baranov, V.A. [Institute for Introscopy, Tomsk (Russian Federation)

    1999-08-01

    A compact detection system was built for multi-angle inspection of pipes, consisting of a high-sensitivity radiometric line scanner and an ultrasonic manipulator. Improved flaw imaging quality is achieved with this system as compared to film radiography. Measurements have been carried out on site in a nuclear power plant and in a laboratory. Better flaw imaging quality was also achieved in the testing of water-filled pipes. Non-linear tomosynthesis was applied for processing and interpretation of measured data. The system delivers considerably better images of planary materials inhomogeneitites, (such as cracks and lack-of-bond defects). (orig./CB) [Deutsch] Eine hoch empfindliche radiometrische Zeilenkamera wurde mit einem Ultraschall-Manipulator zu einem Gesamtsystem aufgebaut und fuer Mehrwinkel-Inspektionen von Rohrleitungen angewandt. Bei der Inspektion von Rundschweissnaehten an Rohren mit ca. 8... 20 mm Wanddicke wurde eine Verbesserung der Bildqualitaet im Vergleich zur Filmradiographie erreicht. Diese Messungen wurden in einem Kernkraftwerk unter Vor-Ort-Bedingungen sowie im Labor ausgefuehrt. Ein signifikantes Ansteigen der Bildqualitaet wurde auch bei der Pruefung von wassergefuellten Rohren erzielt. Methoden der nicht-linearen Tomosynthese wurden fuer die Verarbeitung und Interpretation der gemessenen Projektionsdaten genutzt. Das entwickelte System gestattet eine erhebliche Verbesserung der Anzeige von planaren Materialinhomogenitaeten (z.B. Risse und Bindefehler). (orig./DGE)

  3. Authors's reply to `Generation of surface degraded layer on austenitic stainless steel piping exposed to flowing sodium in a loop: inter comparison of long term exposure data', by S. Rajendran Pillai

    Science.gov (United States)

    Ganesan, Vaidehi; Ganesan, V.; Borgstedt, H. U.

    2004-09-01

    This is an elaborate author's reply to a comment `Generation of surface degraded layer on austenitic steel piping exposed to flowing sodium in a loop: inter comparison of long term exposure data' by S. Rajendran Pillai appearing in this proceedings. The basic misunderstanding as seen in the above comment about the mass loss due to sodium exposure, which is reflected throughout the above comment, has been explained in detail in this reply for better understanding of the phenomenon. It is precisely mentioned and understood that Thorley and Tyzack model deals with complete mass loss and not mere degradation. The total mass loss corresponds to mass loss due to wall thinning and that due to degraded layer formation. Though Thorley and Tyzack model is the most pioneering model in the field of sodium corrosion, the inadequacies of this model for materials without molybdenum such as SS 304 with very long exposure in sodium is clearly brought out in this paper. This model has been successfully applied to calculate life of clad tubes, which have relatively short stay in reactor core. Yoshida models are highlighted and compared with our experimental results. Yoshida models are not valid below certain durations owing to the empirical nature of such expressions. Thorley and Tyzack model can be used for SS 316 LN as this alloy contains molybdenum and nitrogen both of which imparts corrosion resistance in sodium. What is required is that one needs to establish the extent to which this model can be applied for materials exposed to high temperatures and very long durations. The details are discussed in this reply.

  4. Cementite Solidification in Cast Iron

    Science.gov (United States)

    Coronado, J. J.; Sinatora, A.; Albertin, E.

    2014-06-01

    Two hypereutectic cast irons (5.01 pct Cr and 5.19 pct V) were cast and the polished surfaces of test pieces were deep-etched and analyzed via scanning electron microscopy. The results show that graphite lamellae intersect the cementite and a thin austenite film nucleates and grows on the cementite plates. For both compositions, graphite and cementite can coexist as equilibrium phases, with the former always nucleating and growing first. The eutectic carbides grow from the austenite dendrites in a direction perpendicular to the primary plates.

  5. 铸钢管道的电磁激励红外热像无损检测数值模拟研究%Numerical simulation study on NDT of cast steel pipe by electromagnetically excited thermography

    Institute of Scientific and Technical Information of China (English)

    方俊雅; 李国华; 高聚春; 胡宇; 林晓凤

    2012-01-01

    The cast steel pipe is often applied to petrochemical industry, and non-destructive testing has very important meaning in ensuring its product quality. According to the electromagnetic heat coupling analysis theory, a large-scale finite element analysis software ANSYS was used to conduct the simulation and calculation of the cast steel pipe so as to reduce the time and cost of non-destructive testing. The defect inspection laws such as the maximum temperature difference of defect surface, continuable defect inspec- tion duration, maximum detectable continuous defect length etc. was obtained by altering electromagnetic excited frequency, intensity of excited current and defect depth. The inspection results offered valuable ref- erences for non-destructive testing of cast steel pipe by electromagnetically excited thermography.%铸钢管道常用于石油化工工业中,无损检测是保障其质量的重要手段。为了减少无损检测的时间和成本,根据电磁热耦合分析原理,采用大型有限元分析软件ANSYS,对铸钢管道进行模拟仿真运算,通过改变电磁激励频率、激励电流强度和缺陷深度,得到缺陷表面的最大温差、缺陷可检测的持续时间、缺陷可检测的最大连续长度等缺陷规律检测,检测结果为铸钢电磁激励红外热像无损检测提供了有价值的参考。

  6. Steels for large steam pipes

    International Nuclear Information System (INIS)

    Presented are the results of pilot-scale operation and scientific investigation of metal of pipes 500 to 1100 mm in diameter manufactured by various techniques from 15Kh1M1F steel. The structure and the properties of the metal of ten meltings were investigated for homogeneity in the following zones: base metal, near-weld zone and weld metal. It was found that the macrostructure of pipes cast by a centrifugal method has a fairly dense structure; there is homogeneity across and lengthwise of the pipe. After a heat treatment, the metal of centrifugally cast pipes has both high short-time and long-time properties. Introduction of centrifugally cast pipe manufacture opens possibilities for using larger pipes in steam conduits of hot intermediate superheating devices

  7. Studies of aged cast stainless steel from the Shippingport reactor

    International Nuclear Information System (INIS)

    The cast stainless steels used for primary coolant piping in many pressurized water reactors and for valve bodies, fittings, and coolant pump casings in most light water reactors are subject to embrittlement after extended service at reactor operating temperatures. Most studies pertaining to embrittlement of cast stainless steels involve simulation of end-of-life reactor conditions by accelerated aging at ≥400 degrees C since the time period for operation of a power plant is far longer than can generally be considered for laboratory studies. Thus, an assessment of the end-of-life mechanical properties is almost always based on an extrapolation of the accelerated test data. Because the embrittlement mechanisms and kinetics are complex, microstructural studies and mechanical testing of actual component materials that have completed long in-reactor service are needed to ensure that the mechanisms observed in accelerated aging experiments are the same as those occurring in reactor. Cast stainless steel materials from the decommissioned Shippingport reactor offered a unique opportunity to validate and benchmark the laboratory studies. Cast stainless steel materials were obtained from four primary coolant system check valves, two manual hot-leg isolation valves, and two pump volutes. Microstructural examination of the cast materials indicates that the primary mechanism of thermal embrittlement is the same as that of laboratory-aged materials, i.e., spinodal decomposition of the ferrite to form chromium-rich α' phase. Other phases, such as nickel- and silicon-rich G phase precipitated in the ferrite, and the presence of carbides at the austenite/ferrite phase boundary also contribute to embrittlement. Charpy-impact, tensile, and J-R curve tests were conducted on several cast stainless steels from the Shippingport reactor

  8. Analysis of the structure of castings made from chromium white cast iron resistant to abrasive wear

    Directory of Open Access Journals (Sweden)

    D. Kopyciński

    2009-10-01

    Full Text Available It has been proved that an addition of boron carbide and disintegrated steel scrap introduced as an inoculant to the chromium white cast iron changes the structure of castings. The said operation increases the number of crystallization nuclei for dendrites of the primary austenite. In this case, the iron particles act as substrates for the nucleation of primary austenite due to a similar crystallographic lattice. The more numerous are the dendrites of primary austenite and the structure more refined and the mechanical properties higher. Castings after B4C inoculation revealed a different structure of fine grained fracture. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  9. Effect of Manganese on As-Cast Microstructure and Hardening Behavior of High Chromium White Cast Iron

    Institute of Scientific and Technical Information of China (English)

    SUN Zhi-ping; SHEN Bao-luo; WANG Jun; LIU Hao-huai; LUO Cheng

    2005-01-01

    The effect of manganese on the as-cast structure and hardening behavior of high chromium white cast iron subjected to sub-critical treatment was studied. The results indicate that the fraction of retained austenite and the manganese distribution in as-cast alloys are controlled by manganese content. The manganese distribution in as-cast alloys is not homogeneous. The manganese content in carbide is higher than that in matrix. Whether the secondary hardening occurs or not and the peak hardness of secondary hardening is controlled by manganese content in retained austenite in as-cast structure. Higher manganese content can cause more retained austenite. The secondary hardening occurs in sub-critical treating process if the fraction of retained austenite is high.

  10. Pitting corrosion resistant austenite stainless steel

    Science.gov (United States)

    van Rooyen, D.; Bandy, R.

    A pitting corrosion resistant austenite stainless steel comprises 17 to 28 wt. % chromium, 15 to 26 wt. % nickel, 5 to 8 wt. % molybdenum, and 0.3 to 0.5 wt. % nitrogen, the balance being iron, unavoidable impurities, minor additions made in the normal course of melting and casting alloys of this type, and may optionally include up to 10 wt. % of manganese, up to 5 wt. % of silicon, and up to 0.08 wt. % of carbon.

  11. Degradation of stainless castings. A literature study

    International Nuclear Information System (INIS)

    Duplex cast stainless steels, containing mainly austenite and some ferrite, is used for different components in light water reactors. These alloys have good mechanical properties, good weldability, and they are resistant to intergranular stress corrosion cracking (IGSCC). Examples of components where cast duplex stainless steel is used are pump housings, valves and pipe elbows. A model for the aging/embrittlement of these materials when used in light water reactors has been developed. The model is based on regression of a large data matrix. It is mainly the impact energy (Charpy V) that has been regarded. The model only requires knowledge of the chemical composition of the material but the prediction can be improved if additional data like initial impact properties and measured ferrite content are available. The model is also capable of predicting fracture toughness. The susceptibility to IGSCC in BWR environment is primarily determined by the amount of ferrite and the carbon content of the material. When the amount of ferrite exceeds 12%, IGSCC has not been observed regardless of the carbon content. At carbon contents lower than 0.035% in weld-sensitized material IGSCC was not observed regardless of the ferrite content. Data for corrosion fatigue in primary PWR and BWR environment are available. Under BWR conditions the crack propagation rate is decreased with decreasing corrosion potential, consequently also with decreasing oxygen content of the water. Some areas have been identified where additional work is needed. In all cases the efforts should focus on characterizing cast duplex stainless steel components removed from Swedish reactors. The characterization should include: Microstructure and chemical analysis, susceptibility to IGSCC, and a comparison with existing models for embrittlement. 24 refs, 12 figs

  12. QUALITY CONTROL ON THE AUSTENITIC-BAINITIC DUCTILE IRON GEAR

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    By reasonable casting, spheroidizing , inoculating and heat treating processes to control cupola metallurgy and the lipuid iron chemical compositions, a new kind of austenitic-bainitic ductile iron which can substitute for 20CrMnTi carburizing steel is studied. The gears made by the cast iron are high in quality,low in weight and the production cost is greatly reduced. The mechanical properties of the gear, including wear resistance, fatigue resistance, durability and others, can be greatly improved.

  13. Ice plugging of pipes using liquid nitrogen

    International Nuclear Information System (INIS)

    This report presents a study on the ice plugging of pipe using liquid nitrogen, and is based on a literature review and on discussions with individuals who use the technique. Emphasis is placed on ferritic alloys, primarily carbon steels, in pipe sized up to 60 cm in diameter and on austenitic stainless steels in pipe sizes up to 30 cm in diameter. This technique is frequently used for leak testing in nuclear facilities

  14. 49 CFR 192.373 - Service lines: Cast iron and ductile iron.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Cast iron and ductile iron. 192.373... Regulators, and Service Lines § 192.373 Service lines: Cast iron and ductile iron. (a) Cast or ductile iron... cast iron pipe or ductile iron pipe is installed for use as a service line, the part of the...

  15. 铸铁管道胶圈承插接口抗震性能试验研究%Experimental research on seismic capability of cast-iron pipe with rubber gasket joints

    Institute of Scientific and Technical Information of China (English)

    陈春光; 杨庆华; 孔杰; 解晓杰; 廖倩

    2012-01-01

    Ductile cast iron pipe is a tubular product, which is frequently used in city water-supply project. The seismic capability of joints is one of the factors, which must be considered in the design of water-supply network in seismic areas. To study the mechanical parameters of rubber gasket joints, a series of prototype drawing experiment are performed lo investigate the regularity of joints drawing force and the joints displacement. The experimental results show that, rubber gasket joints for ductile cast iron pipe is favorable for earthquake-resistance; the allowed maximum joints displacement is about 3 ~4cm; the joints spring coefficient is between 32N/cm· cm-2 to 125 N/ cm ·cm-2and the maximum resistance is about 45 ~75N/cm2.%铸铁管道是城市供水工程常用的管材,其接口的抗震性能是地震多发地区供水管网设计必须考虑的因素之一.为研究胶圈承插接口的力学性能参数,采用了原型拉拔试验,测定了管道胶圈接口拉拔力与接口变形量,通过试验数据分析,证明了胶圈承插接口具有良好的抗震性能,接头最大允许变形量可达3~4cm,测定出铸铁管胶圈承插接口单位接触面积弹簧系数值在32~125N/(cm·cm2)之间、单位接触面积接头最大抗力为45~75N/cm2.

  16. Life evaluation of cast duplex stainless steel elbows in French PWR NPP

    International Nuclear Information System (INIS)

    The principal primary circuit cast elbows of French PWR are in austenitic-ferritic cast stainless steel CF8 - CF8M types. This material is sensitive to thermal aging at PWR operating temperatures. The aging results in a diminishment of tearing resistance characteristics, and with the possible presence of foundry flaws this could lead to a fear of increased break risk. An extensive program on material properties, inspection, tests in laboratory, flaw evaluations, etc, has been covered out in the last 5 years between EDF and FRAMATOME. This paper presents the major tasks performed to justify a good behaviour of these elbows, and they will remain operational at least for the 40-year design lifetime, the consequences at the maintenance level and the utility point of view. CF8 and CF8M are cast materials, that can have casting defects that we generally assume conservatively as a perfect crack for fracture mechanics analysis. The other fact is that materials can be sensitive to thermal aging that were not clearly quantified at the design level by any international code in the 70's. This paper shows EDF's maintenance strategy for those nuclear power plants at present being operated. One important task described in this paper is the material toughness evaluation work proposed to cover all the pipe elbows in 3 loops and 4 loops nuclear power plants. Presently, all the EDF PWR elbows can be used safely for the 40 year design period, some complementary work is in progress to support this conclusion. (author)

  17. Cast functional accessories for heat treatment furnaces

    Directory of Open Access Journals (Sweden)

    A. Drotlew

    2010-10-01

    Full Text Available The study gives examples of the cast functional accessories operating in furnaces for the heat treatment of metals and alloys. The describeddesign solutions of castings and their respective assemblies are used for charge preparation and handling. They were put in systematicorder depending on furnace design and the technological purpose of heat treatment. Basic grades of austenitic cast steel, used for castings of this type, were enumerated, and examples of general guidelines formulated for their use were stated. The functional accessories described in this study were designed and made by the Foundry Research Laboratory of West Pomeranian University of Technology.

  18. Exploitation of rare earth metals in cast steel production for power engineering

    Directory of Open Access Journals (Sweden)

    J. Kasińska

    2008-12-01

    Full Text Available The paper presents results of experiments carried out on industrial melts. There has been tested the REM influence on carbon properties (0.20%C as well as austenitic cast steel Cr-Ni 18/8+Ti type.It was found that REM cause an essential improvement of cast steels impact strength and in case of austenitic cast steel – also the corrosion resistance improvement in boiling 65%HNO3 (Huey test.

  19. RESEARCH AND APPLICATION OF AS-CAST WEAR RESISTANCE HIGH CHROMIUM CAST IRON

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The influence of alloy elements, such as boron and silicon, on the microstructure and properties of as-cast high chromium cast iron is studied. The results show that boron and silicon have a great effect on the mechanical properties and the wear resistance. Through proper addition of boron and silicon, the properties of as-cast high chromium cast iron can be improved effectively. Through analyzing the distribution of elements by scanning electron microscope, it has been shown that the addition of boron and silicon lowers the mass fraction of chromium saturated in as-cast austenite, and makes it unstable and liable to be transformed into martensite. The as-cast high chromium cast iron with proper content of boron and silicon is suitable for the manufacture of lining for asphalt concrete mixer and its wear resistance is 14 times that of lining made of low alloy white cast iron.

  20. Failure of austenitic stainless steel tubes during steam generator operation

    OpenAIRE

    M. Głowacka; J. Łabanowski; S. Topolska

    2012-01-01

    Purpose: of this study is to analyze the causes of premature failure of steam generator coil made of austenitic stainless steel. Special attention is paid to corrosion damage processes within the welded joints.Design/methodology/approach: Examinations were conducted several segments of the coil made of seamless cold-formed pipes Ø 23x2.3 mm, of austenitic stainless steel grade X6CrNiTi18-10 according to EN 10088-1:2007. The working time of the device was 6 months. The reason for the withdrawa...

  1. Effect of heat treatment on the high temperature ductility of 00 Cr24 Ni13 austenitic stainless steel casting billets%热处理对奥氏体不锈钢00 Cr24 Ni13铸坯高温热塑性的影响

    Institute of Scientific and Technical Information of China (English)

    舒玮; 李俊; 廉晓洁; 王学敏

    2015-01-01

    采用热处理实验方法,同时结合热模拟压缩和热模拟拉伸试验,研究了热处理对奥氏体不锈钢00Cr24Ni13铸坯高温热塑性的影响。实验结果表明:热处理能够明显改变实验钢铸坯中δ铁素体的形貌;经1200℃保温3 h空冷后,原始铸坯中存在的大面积连续网状δ铁素体完全转变为弥散分布的细小颗粒状组织。具有颗粒状δ铁素体的热处理试样与热处理前相比,不同温度压缩时的变形抗力略有增加,但并没有急剧恶化;热模拟抗拉强度基本保持不变;相同温度下的断面收缩率( Z)显著提高,其中Z≥60%的温度区间由1150~1280℃扩展为1050~1300℃,高塑性(Z≥80%)温度范围在150℃左右(1150~1300℃)。%The effect of heat treatment on the high temperature ductility of 00Cr24Ni13 austenitic stainless steel casting billets was investigated by heat treatment experiment, thermo-compression test and thermal tensile test. The result showed thatδferrite morpholo-gy in the casting billet could be significantly changed through the heat treatment process. After air cooling from 1200℃ for 3 h, large area of continuous reticularδferrite in the casting billet completely changed into dispersed granular phases. Compared with the casting billet before heat treatment, heat-treated samples which are composed of granularδferrite had a higher value of deformation resistance at different compression temperatures, but there was no sharp deterioration in deformation resistance, the thermal simulation tensile strength remained almost the same and the reduction of area ( Z) at the same temperature increased obviously. The temperature region of Z≥60% extended from 1150-1280℃ to 1050-1300℃, and the high plasticity ( Z≥80%) range is about 150℃ ( 1150-1300℃).

  2. The heat treatment of Fermanal cast steel

    Directory of Open Access Journals (Sweden)

    F. Binczyk

    2007-12-01

    Full Text Available The study discloses the results of microstructural examinations, testing of magnetic properties and hardness measurements as cast and after heat treatment conducted on the Fermanal cast steel. A characteristic feature of this cast steel is its density lower by about 10% than the density of carbon cast steel [4]. It has been proved that the factor deciding about the composition of microstructure (fraction of ferrite and austenite is the content of aluminium. The matrix totally austenitic is present in cast steel containing from 0,8 to 0,9% C, from 22 to 24% Mn, and from 4,5 to 5,5% Al. The magnetic properties examined on samples of the Fermanal cast steel were determined by spectroscopy of the Mössbauer effect with isotope 57Fe. The magnetic properties represented by a mean value of the hyperfine magnetic field Bhf and relative magnetic permeability were determined. It has been stated that the level of magnetic properties of the Fermanal cast steel depends on the content of ferrite. The effect of the parameters of solutioning and ageing on the cast steel microstructure and hardness after modification with additions of B, Ti and Nb was investigated.

  3. The quality of the joint between alloy steel and unalloyed cast steel in bimetallic layered castings

    Directory of Open Access Journals (Sweden)

    T. Wróbel

    2012-01-01

    Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. ferritic-pearlitic unalloyed cast steel, whereas working part (layer is plate of austenitic alloy steel sort X2CrNi 18-9. The ratio of thickness between bearing and working part is 8:1. The aim of paper was assessed the quality of the joint between bearing and working part in dependence of pouring temperature and carbon concentration in cast steel. The quality of the joint in bimetallic layered castings was evaluated on the basis of ultrasonic non-destructive testing, structure and microhardness researches.

  4. Numerical simulation of residual stress in piping components at Framatome-ANP

    International Nuclear Information System (INIS)

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

  5. Recent development of ductile cast iron production technology in China

    Directory of Open Access Journals (Sweden)

    Cai Qizhou

    2008-05-01

    Full Text Available Recent progress in the production and technology of ductile cast iron castings in China is reviewed. The manufacture and process control of as-cast ductile iron are discussed. The microstructure, properties and application of partial austenitization normalizing ductile iron and austempered ductile iron (ADI are briefl y depicted. The new development of ductile iron production techniques, such as cored-wire injection (wire-feeding nodularization process, tundish cover ladle nodularizing process, horizontal continuous casting, and EPC process (lost foam for ductile iron castings, etc., are summarized.

  6. Recent development of ductile cast iron production technology in China

    Institute of Scientific and Technical Information of China (English)

    Cai Qizhou; Wei Bokang

    2008-01-01

    Recent progress in the production and technology of ductile cast iron castings in China is reviewed.The manufacture and process control of as-cast ductile iron are discussed.The microstructure.properties and application of partial austenitization normalizing ductile iron and austempered duclile iron(ADI)are briefly depicted.The new development of duclile iron production techniques,such as cored-wire injection(wire-feeding nodularization)process,tundish cover ladle nodularizing process,horizontal continuous casting,and EPC process (lost foam)for ductile iron castings,etc.,are summarized.

  7. Improving chill control in iron powder treated slightly hypereutectic grey cast irons

    OpenAIRE

    Iulian Riposan; Mihai Chisamera; Stelian Stan

    2011-01-01

    Recent studies revealed that in eutectic to slightly hypereutectic grey irons (CE = 4.3%-4.5%) the presence of austenite dendrites provides an opportunity to improve the cast iron properties, as a high number of eutectic cells are “reinforced” by austenite dendrites. An iron powder addition proved to be important by promoting dendritic austenite in hypereutectic irons, but was accompanied by adverse effect on the characteristics of potential nuclei for graphite. The purpose of the present pap...

  8. Effect of casting technology on microstructure and phases of high carbon high speed steel

    OpenAIRE

    Zhang Tianming; Wang Qinjuan; Song Xuding

    2011-01-01

    The as-cast microstructures of high carbon high speed steels (HC-HSS) made by sand casting, centrifugal casting and electromagnetic centrifugal casting, respectively, were studied by using of optical microscopy (OM) and D/max2200pc X-ray diffraction. The results show that the microstructure of as-cast HC-HSS is dominated by alloy carbides (W2C, VC, Cr7C3), martensite and austenite. The centrifugal casting and electromagnetic centrifugal casting apparently improve the solidification structure ...

  9. A repair process for an heterogenous welded joint between a nuclear reactor component tube and a pipe

    International Nuclear Information System (INIS)

    The repairing process involves cutting a tubular section of the tube and the pipe, which includes the welded joint, and preparing an austenitic stainless steel tubular section for substitution; the section is then narrow-joint welded with the low-alloy steel tube, and finally welded to the austenitic stainless steel pipe. Application to repairing a welded joint between a PWR pressurizer tube and the expansion pipe of the pressurizer. (authors). 7 refs., 3 figs

  10. Proceedings of the specialists' meeting on reliability of the ultrasonic inspection of austenitic materials

    International Nuclear Information System (INIS)

    The contributions of this meeting addressed several topics: the fundamentals of ultrasonic examination of austenitic materials (effect of anisotropy on propagation, improvement of ultrasonic testing to thick bimetallic welds, aspects of the ultrasonic testing of austenitic steel structures, utilization of a Fisher linear discriminant function in intergranular stress corrosion cracking or IGSCC detection, case of coarse grain austenitic welds, efforts of the Argonne National Laboratory), instruments and methods (longitudinal wave ultrasonic inspection, Grass echo suppression technique during the ultrasonic inspection of fuel cladding tubes, inspections of fillet and butt welds, improvement by signal averaging techniques, multiple bearing angle crack detector for cladded pipes examinations, flow-to-grain echo enhancement by split-spectrum processing, ultrasonic imaging techniques, ultrasonic inspection of pipe weldments for IGSCC), industrial practice (ultrasonic testing techniques for fabrication and in-service inspection, experiences in ultrasonic examination of austenitic steel components, experience and practice on nuclear piping in Spain, detection of underclad defects, sizing of cracks perpendicular to stainless overlay), and reliability (survey of ultrasonic testing in austenitic weld material, examination of electron beam welds, factors affecting the reliability of ultrasonic examination, detectability of IGSCC, ultrasonic inspection reliability for primary piping systems)

  11. Technical Letter Report, An Evaluation of Ultrasonic Phased Array Testing for Reactor Piping System Components Containing Dissimilar Metal Welds, JCN N6398, Task 2A

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Aaron A.; Cinson, Anthony D.; Crawford, Susan L.; Anderson, Michael T.

    2009-11-30

    Research is being conducted for the U.S. Nuclear Regulatory Commission at the Pacific Northwest National Laboratory to assess the effectiveness and reliability of advanced nondestructive examination (NDE) methods for the inspection of light-water reactor components. The scope of this research encom¬passes primary system pressure boundary materials including dissimilar metal welds (DMWs), cast austenitic stainless steels (CASS), piping with corrosion-resistant cladding, weld overlays, inlays and onlays, and far-side examinations of austenitic piping welds. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in steel components that challenge standard and/or conventional inspection methodologies. This interim technical letter report provides a summary of a technical evaluation aimed at assessing the capabilities of phased-array (PA) ultrasonic testing (UT) methods as applied to the inspection of small-bore DMW components that exist in the reactor coolant systems (RCS) of pressurized water reactors (PWRs). Operating experience and events such as the circumferential cracking in the reactor vessel nozzle-to-RCS hot leg pipe at V.C. Summer nuclear power station, identified in 2000, show that in PWRs where primary coolant water (or steam) are present under normal operation, Alloy 82/182 materials are susceptible to pressurized water stress corrosion cracking. The extent and number of occurrences of DMW cracking in nuclear power plants (domestically and internationally) indicate the necessity for reliable and effective inspection techniques. The work described herein was performed to provide insights for evaluating the utility of advanced NDE approaches for the inspection of DMW components such as a pressurizer surge nozzle DMW, a shutdown cooling pipe DMW, and a ferritic (low-alloy carbon steel)-to-CASS pipe DMW configuration.

  12. COMPLEX RECONSTRUCTION OF THE CONTINUOUS CASTING MACHINES OF BELARUSIAN STEEL WORKS

    Directory of Open Access Journals (Sweden)

    A. A. Sotnikov

    2012-01-01

    Full Text Available Set of activities performed by the machine for continuous casting mill № 3 has enhanced its productivity and also master a new product - continuous casting round billet for seamless drawn pipes in tube-rolling shop

  13. Effects of Rare Earths and Al on Structure and Performance of High Chromium Cast Iron Containing Wolfram

    Institute of Scientific and Technical Information of China (English)

    Guo Erjun; Wang Liping; Huang Yongchang; Fu Yuanke

    2006-01-01

    Effects of RE and Al on the structure, impact toughness, hardness, and wear resistance of high chromium cast iron containing wolfram were investigated.The results show that without modification the volume fraction of austenite is high and the carbide appears to be thick lath and the grain size is relatively large;proper modification using RE combined with Al can reduce volume fraction of residual austenite in the as-cast structure obviously, refine grain size of primary austenite notably, and make the morphology of carbide changing from thick lath to thin lath, rosette, and feather-like modification can also increase hardness, wear resistance and impact toughness of cast iron.

  14. Investigation on Mechanical Property of Seamless Pipe

    Institute of Scientific and Technical Information of China (English)

    ZHAO Li-ming; YANG Xiao-yong; LIU Ye

    2004-01-01

    The mechanical properties of the steel pipe rolled with continuously casting round billet after determining the chemical composition in steel were studied. The results show that the total reduction ratio should be higher than 5.2 when the line pipes of grade B, grade 20 and other general seamless pipe were rolled with continuously casting round billet. And the total reduction ratio should be higher than 10.2 and the grain size should be controlled more than grade 7 for casing of oil countryside tubular goods (OCTG).

  15. Thermal-aging evaluation of on site aged cast duplex stainless steel

    International Nuclear Information System (INIS)

    Cast duplex stainless steel was widely used for main coolant pipe in pressurized water reactors, they can suffer a loss of toughness after long-term thermal-aging. To evaluate mechanical properties of such as thermal-aged materials was investigated in laboratory using accelerated aged materials. In addition, to investigate the degradation mechanism, micro-structural behaviors were also investigated. According to such as laboratory data, main cause of degradation of these materials was considered ferrite hardening by spinodal decomposition and G-phase precipitation in the ferrite phase. In this study, thermal-aging evaluation has been performed using service aged elbow pipe in PWR plant, aged at 320℃ for 196,500h. Thermal-aging were evaluated using atom-probe analysis, scanning transmission electron microscope, and micro-Vickers hardness measurement. And then those parameters were compared accelerated thermal-aged materials. As a result, micro Vickers hardness of ferrite in service material (SCS14A), HV(0.025) was 616-630. Since micro Vickers hardness of un-aged ferrite phase is about HV(0.025)=300 in commercial SCS14A, the increasing of ferrite hardness during aging was 300. Cr-rich and Fe-rich regions were observed in the ferrite phase using Atom-probe analysis. In addition, Ni, Si and Mo clustering were also observed in the ferrite phase. So the ferrite phase was hardened caused by these micro-structural changes. Micro Vickers hardness of austenite phase, HV (0.025) was 155-180. Since micro Vickers hardness of un-aged austenite phase is about HV (0.025)=180-200, and no micro-structural change was observed in the austenite phase, so no change was observed in the austenite phase during aging. To compare the micro Vickers hardness of ferrite in service and accelerated materials using activation energy, Q=100kJ/mol, the ferrite hardness of in service material was very low rather than predictive line. This seems the activation energy was too conservative. (author)

  16. Results of VGB research work with respect to operation of BWR pipes made of austenitic SS; Ergebnisse des VGB-Forschungsvorhabens zur Absicherung des Betriebsverhaltens austenitischer Staehle in SWR-Rohrleitungen

    Energy Technology Data Exchange (ETDEWEB)

    Kilian, R. [Siemens AG Energieerzeugung KWU, Erlangen (Germany); Bruemmer, G. [Hamburgische Electricitaets-Werke AG, Hamburg (Germany)

    1998-11-01

    The VGB research project was to examine and characterize various, operation-induced impacts on the crack formation in stabilized austenitic steels, caused by intercrystalline stress corrosion cracking as a result of sensitization after chromium depletion at the grain boundaries. The results of this project as well as available operating experience show that the measures taken so far for the future operation of the German BWR plants, for avoiding in these plants intercrystalline stress corrosion cracking, correspond to the state of the art and achieve the wanted purpose. These measures are: use of optimized material W-No. 1.4550 with reduced carbon contents; use of optimized welding techniques for reducing the heat input and the welding shrinkage (cold deformation.); optimized preparation of welding work in order to avoid shape defects during welding (eg. edge misalignment, defective mash welds); reduction of tensile stresses occurring during welding; compliance with the recent VGB water chemistry code. (orig./CB) [Deutsch] Das VGB-Forschungsvorhaben sollte verschieden gelagerte Einfluesse auf die Rissbildung im Betrieb von stabilisierten austenitischen Staehlen, verursacht durch interkristalline Spannungsrisskorrosion infolge Sensbilisierung durch Chromverarmung an den Korngrenzen, systematisch erfassen. Aus den Forschungsergebnissen dieses VGB-Programms sowie den bisher vorliegenden Betriebserfahrungen ist festzuhalten, dass die bisher durchgefuehrten Massnahmen fuer den zukuenftigen Betrieb der deutschen SWR-Anlagen zur Vermeidung von interkristalliner Spannungsrisskorrosion zielgerichtet waren und dem heutigen Wissensstand entsprechen. Diese Massnahmen sind: 1. Einsatz von optimiertem Werkstoff W.-Nr. 1.4550 mit abgesenktem Kohlenstoffgehalt; 2. Einsatz von optimierten Schweissverfahren zur Verminderung der Waermeeinbringung und zur Verringerung des Schweissschrumpfes (Kaltverformung.); 3. Durchfuehrung einer optimierten Schweissnahtvorbereitung zur Vermeidung

  17. Fracture toughness of CF8 stainless steel castings in liquid helium

    International Nuclear Information System (INIS)

    Fracture toughness measurements for CF8 stainless steel castings in liquid helium at 4 K are reported. Single-phase (austenite) and duplex (austenite + delta-ferrite) castings were tested. On the basis of estimates from J-integral data, the plane-strain fracture toughness (K/sub Ic/) of castings containing 3.2 to 14.5% delta-ferrite ranged from 84 to 179 MPa.m/sup 1/2/ at 4 K. In contrast, a fully austenitic casting (0% delta-ferrite) exhibited a K/sub Ic/ value of 331 MPa.m/sup 1/2/, which is nearly equivalent to the toughness of a wrought AISI 304 stainless steel of a similar strength. Optical and scanning electron microscopy studies indicate that the inferior toughness of castings containing delta-ferrite may be chiefly attributed to the brittlemenss of this body-centered-cubic phase at cryogenic temperatures and its distribution in the microstructure

  18. Influence of the cooling rate on the corrosion resistance of duplex cast steel

    Directory of Open Access Journals (Sweden)

    B. Kalandyk

    2013-01-01

    Full Text Available The results of the influence of the cooling rate of the casting made of the acid-resistant ferritic - austenitic cast steel on the microstructure and corrosion resistance are presented in the paper. Samples cut out from the walls of the casting being cooled at the cooling rate of 3,2 - 0,5 ºC/s were used in the study. Different cooling rates create favorable conditions for the segregation processes lowering properties of castings. It was found, that differences in the polarization curves occur only in the more aggressive corrosive environment. The reason of such behaviour of cast steel is the segregation of elements dissolved in austenite and the difference in the volume fraction of ferrite and austenite in the walls of the different thickness.

  19. Failure of austenitic stainless steel tubes during steam generator operation

    Directory of Open Access Journals (Sweden)

    M. Głowacka

    2012-12-01

    Full Text Available Purpose: of this study is to analyze the causes of premature failure of steam generator coil made of austenitic stainless steel. Special attention is paid to corrosion damage processes within the welded joints.Design/methodology/approach: Examinations were conducted several segments of the coil made of seamless cold-formed pipes Ø 23x2.3 mm, of austenitic stainless steel grade X6CrNiTi18-10 according to EN 10088-1:2007. The working time of the device was 6 months. The reason for the withdrawal of the generator from the operation was leaks in the coil tube caused by corrosion damage. The metallographic investigations were performed with the use of light microscope and scanning electron microscope equipped with the EDX analysis attachment.Findings: Examinations of coil tubes indicated severe corrosion damages as pitting corrosion, stress corrosion cracking, and intergranular corrosion within base material and welded joints. Causes of corrosion was defined as wrong choice of austenitic steel grade, improper welding technology, lack of quality control of water supply and lack of surface treatment of stainless steel pipes.Research limitations/implications: It was not known the quality of water supply of steam generator and this was the reason for some problems in the identification of corrosion processes.Practical implications: Based on the obtained research results and literature studies some recommendations were formulated in order to avoid failures in the application of austenitic steels in the steam generators. These recommendations relate to the selection of materials, processing technology and working environment.Originality/value: Article clearly shows that attempts to increase the life time of evaporator tubes and steam coils by replacing non-alloy or low alloy structural steel by austenitic steel, without regard to restrictions on its use, in practice often fail.

  20. Finite element thermal analysis of the fusion welding of a P92 steel pipe

    OpenAIRE

    Yaghi, A. H.; Tanner, D. W. J.; Hyde, T.H.; A. A. Becker; Sun, W.

    2012-01-01

    Fusion welding is common in steel pipeline construction in fossil-fuel power generation plants. Steel pipes in service carry steam at high temperature and pressure, undergoing creep during years of service; their integrity is critical for the safe operation of a plant. The high-grade martensitic P92 steel is suitable for plant pipes for its enhanced creep strength. P92 steel pipes are usually joined together with a similar weld metal. Martensitic pipes are sometimes joined to austenitic steel...

  1. Evaluation of aging of cast stainless steel components

    International Nuclear Information System (INIS)

    Cast stainless steel is used extensively in nuclear reactors for primary-pressure-boundary components such as primary coolant pipes, elbows, valves, pumps, and safe ends. These components are, however, susceptible to thermal aging embrittlement in light water reactors because of the segregation of Cr atoms from Fe and Ni by spinodal decomposition in ferrite and the precipitation of Cr-rich carbides on ferrite/austenite boundaries. A recent advance in understanding the aging kinetics is presented. Aging kinetics are strongly influenced by the synergistic effects of other metallurgical reactions that occur in parallel with spinodal decomposition, i.e., clustering of Ni, Mo, and Si solute atoms and the nucleation and growth of G-phase precipitates in the ferrite phase. A number of methods are outlined for estimating aging embrittlement under end-of-life of life-extension conditions, depending on several factors such as degree of permissible conservatism, availability of component archive material, and methods of estimating and verifying the activation energy of aging. 33 refs., 6 figs., 3 tabs

  2. Thermal Aging Phenomena in Cast Duplex Stainless Steels

    Science.gov (United States)

    Byun, T. S.; Yang, Y.; Overman, N. R.; Busby, J. T.

    2016-02-01

    Cast stainless steels (CASSs) have been extensively used for the large components of light water reactor (LWR) power plants such as primary coolant piping and pump casing. The thermal embrittlement of CASS components is one of the most serious concerns related to the extended-term operation of nuclear power plants. Many past researches have concluded that the formation of Cr-rich α'-phase by Spinodal decomposition of δ-ferrite phase is the primary mechanism for the thermal embrittlement. Cracking mechanism in the thermally-embrittled duplex stainless steels consists of the formation of cleavage at ferrite and its propagation via separation of ferrite-austenite interphase. This article intends to provide an introductory overview on the thermal aging phenomena in LWR-relevant conditions. Firstly, the thermal aging effect on toughness is discussed in terms of the cause of embrittlement and influential parameters. An approximate analysis of thermal reaction using Arrhenius equation was carried out to scope the aging temperatures for the accelerated aging experiments to simulate the 60 and 80 years of services. Further, an equilibrium precipitation calculation was performed for model CASS alloys using the CALPHAD program, and the results are used to describe the precipitation behaviors in duplex stainless steels. These results are also to be used to guide an on-going research aiming to provide knowledge-based conclusive prediction for the integrity of the CASS components of LWR power plants during the service life extended up to and beyond 60 years.

  3. Thermal Aging Phenomena in Cast Duplex Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Thak Sang; Yang, Ying; Overman, Nicole R.; Busby, Jeremy T.

    2016-02-28

    Cast stainless steels (CASSs) have been extensively used for the large components of light water reactor (LWR) power plants such as primary coolant piping and pump casing. The thermal embrittlement of CASS components is one of the most serious concerns related to the extended-term operation of nuclear power plants. Many past researches have concluded that the formation of Cr–rich α'-phase by Spinodal decomposition of δ-ferrite phase is the primary mechanism for the thermal embrittlement. Cracking mechanism in the thermally-embrittled duplex stainless steels consists of the formation of cleavage at ferrite and its propagation via separation of ferrite-austenite interphase. This article intends to provide an introductory overview on the thermal aging phenomena in LWR relevant conditions. Firstly, the thermal aging effect on toughness is discussed in terms of the cause of embrittlement and influential parameters. An approximate analysis of thermal reaction using Arrhenius equation was carried out to scope the aging temperatures for the accelerated aging experiments to simulate the 60 and 80 years of services. Further, equilibrium precipitation calculation was performed for model CASS alloys using the CALPHAD program and the results are used to describe the precipitation behaviors in duplex stainless steels. These results are also to be used to guide an on-going research aiming to provide knowledge-based conclusive prediction for the integrity of the CASS components of LWR power plants during the service life extended up to and beyond 60 years.

  4. A repair process for an heterogenous welded joint between a nuclear reactor component tube and a pipe

    International Nuclear Information System (INIS)

    The repairing process involves cutting a tubular section of the tube (made of low alloy steel) and the pipe (made of austenitic stainless steel), which includes the welded joint, and preparing an heterogenous tubular section for substitution (a first section, made of ferritic steel, is butt welded to a second section, made of austenitic stainless steel); the tubular section is then narrow-joint welded with the low-alloy steel tube, and finally welded to the austenitic stainless steel pipe. Application to repairing a welded joint between a pressurizer tube and an expansion pipe connected to the primary circuit. (author). 5 refs., 4 figs

  5. SPRAY CASTING

    OpenAIRE

    SALAMCI, Elmas

    2010-01-01

    ABSTRACT This paper is designed to provide a basic review of spray casting. A brief overview of the historical development of spray  casting and the description of plant and equipment have been given. Following metallurgical characteristics of spray formed alloys, process parameters and solidification mechanism of spray deposition have been discussed in detail. Finally, microstructure and mechanical properties of the selected spray cast Al-Zn-Mg-Cu alloys have been presented and compared...

  6. Fracture toughness of CF8 castings at four kelvin

    International Nuclear Information System (INIS)

    The first fracture toughness measurements for CF8 stainless steel castings in liquid helium at 4 K are reported. Single-phase (austenite) and duplex (austenite + delta-ferrite) castings were tested. On the basis of estimates from J-integral data, the plane-strain fracture toughness (K /SUB lc/ ) of castings containing 3.2 to 14.5 pct delta-ferrite ranged from 84 to 179 MPa X m /SUP 1/2/ at 4 K. In contrast, a fully austenitic casting (0 pct delta-ferrite) exhibited a K /SUB lc/ value of 331 MPa X m /SUP 1/2/ , which is nearly equivalent to the toughness of a wrought AISI 304 stainless steel of a similar strength. Light and scanning electron microscop studies indicate that the inferior toughness of castings containing delta-ferrite may be attributed to the brittleness of this body-centered-cubic phase at cryogenic temperatures and its distribution in th microstructure. The relative stability of the austenitic phase with respect to martensitic phase transformation may also play a significant role

  7. Expanded austenite in nitrided layers deposited on austenitic and super austenitic stainless steel grades

    International Nuclear Information System (INIS)

    In this work nitrided layers deposited on austenitic and super austenitic stainless steels were analyzed through optical microscopy and X-rays diffraction analysis (XRD). It was observed that the formation of N supersaturated phase, called expanded austenite, has promoted significant increment of hardness (> 1000HV). XRD results have indicated the anomalous displacement of the diffracted peaks, in comparison with the normal austenite. This behavior, combined with peaks broadening, it was analyzed in different nitriding temperatures which results showed good agreement with the literature. (author)

  8. Study on thermal aging mechanism of cast duplex stainless steel

    International Nuclear Information System (INIS)

    Cast duplex stainless steel is used for reactor coolant piping in pressurized water reactors. However, its toughness is reduced by aging after long time operation. R and D on non-destructive techniques for evaluating the level of aging during in-service inspections has been carried out. A practical technique to evaluate accuracy has not, however, been developed yet. This is because the relationship between microstructural changes and mechanical property changes has not been clearly identified. The aim of this study is to clarify the relationship between the microstructural and mechanical property changes due to aging by examining the process of generation of precipitates. The specimens used in this study were SCS 14 A centrifuged cast stainless steel with three different ferrite content types of 8, 15 and 23%. They were aged at temperatures of 350degC and 400degC for up to 10,000 hours. The mechanical properties were investigated with Charpy impact testing and Vickers hardness testing, and microstructural changes studied with a transmission electron microscope, atom probe analysis and Moessbauer spectroscopy. As a result, the Charpy impact value of the specimen with larger ferrite content decreased the most. The hardness of the austenite phase remained almost unchanged while the hardness of the ferrite phase significantly increased. The ferrite hardness increase and the phase decomposition rate were almost the same among the three specimens with different ferrite contents. G phase precipitation was observed for the ferrite materials of 15% and 23% after the long period of thermal aging. In conclusion, the thermal aging degradation can be evaluated by detecting the ferrite phase decomposition rate, the ferrite content and the G phase precipitation. (author)

  9. Modelling of Eutectic Saturation Influence on Microstructure in Thin Wall Ductile Iron Casting Using Cellular Automata

    Directory of Open Access Journals (Sweden)

    M. Górny

    2012-12-01

    Full Text Available The mathematical model of the globular eutectic solidification in 2D was designed. Proposed model is based on the Cellular AutomatonFinite Differences (CA-FD calculation method. Model has been used for studies of the primary austenite and of globular eutectic grainsgrowth during the ductile iron solidification in the thin wall casting. Model takes into account, among other things, non-uniformtemperature distribution in the casting wall cross-section, kinetics of the austenite and graphite grains nucleation, and non-equilibriumnature of the interphase boundary migration. Calculation of eutectic saturation influence (Sc = 0.9 - 1.1 on microstructure (austenite and graphite fraction, density of austenite and graphite grains and temperature curves in 2 mm wall ductile iron casting has been done.

  10. Changes of Tempering Microstructure and Properties of Fe-Cr-V-Ni-Mn-C Cast Alloys

    Institute of Scientific and Technical Information of China (English)

    LIU Yan-xia; MA Yong-qing; WANG Yue-hua; ZHANG Zhan-ping; ZHANG Yang

    2004-01-01

    The changes of tempering microstructure and properties of Fe-Cr-V-Ni-Mn-C cast alloys with martensite matrix and much retained austenite are studied. The results showed that when tempering at 200℃ the amount of retained austenite in the alloys is so much that is nearly to as-cast, and a lot of retained austenite decomposes when tempering at 350℃ and the retained austenite decomposes almost until tempering at 560℃. When tempering at 600℃, the retained austenite in the alloys all decomposes. At 560℃ the hardness is highest due to secondary hardening. The effect of nickel and manganese on the microstructure and properties of Fe-Cr-V-C cast alloy were also studied. The results show that the Fe-Cr-V-C cast alloy added nickel and manganese can obtain martensite matrix and much retained austenite microstructure, and nickel can also prevent pearlite transformation. With the increasing content of nickel and manganese, the hardness of as-cast alloy will decreases gradually, so one can improve the hardness of alloy by tempering process. When the content of nickel and manganese is 1.3~1.7%, the hardness of secondary hardening is the highest (HRC64). But when the content of nickel and manganese increase continually, the hardness of secondary hardening is low slightly, and the tempering temperature of secondary hardening rises.

  11. Phase Transformation in Cast Superaustenitic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Nathaniel Steven Lee Phillips

    2006-12-12

    Superaustenitic stainless steels constitute a group of Fe-based alloys that are compositionally balanced to have a purely austenitic matrix and exhibit favorable pitting and crevice corrosion resistant properties and mechanical strength. However, intermetallic precipitates such as sigma and Laves can form during casting or exposure to high-temperature processing, which degrade the corrosion and mechanical properties of the material. The goal of this study was to accurately characterize the solid-solid phase transformations seen in cast superaustenitic stainless steels. Heat treatments were performed to understand the time and temperature ranges for intermetallic phase formations in alloys CN3MN and CK3MCuN. Microstructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy and wavelength dispersive spectroscopy (EDS, WDS). The equilibrium microstructures, composed primarily of sigma and Laves within purely austenitic matrices, showed slow transformation kinetics. Factors that determine the extent of transformation, including diffusion, nucleation, and growth, are discussed.

  12. Inoculated Slightly Hypereutectic Gray Cast Irons

    Science.gov (United States)

    Chisamera, Mihai; Riposan, Iulian; Stan, Stelian; Militaru, Cristina; Anton, Irina; Barstow, Michael

    2012-03-01

    The current experimental investigation in this article was designed to characterize the structure of mold (M) and ladle (L) inoculated, low-S (0.025 wt.% S), low-Al (0.003 wt.% Al), slightly hypereutectic (CE = 4.4-4.5 wt.%) electric melted gray irons, typical for high performance thin-wall castings. It describes the effect of a Ca, Al, Zr-FeSi inoculant addition of 0-0.25 wt.% on structure characteristics, and compares to similar treatments with hypoeutectic irons (3.5-3.6 wt.% CE, 0.025 wt.% S, and 0.003 wt.% Al). A complex structure including primary graphite, austenite dendrites, and eutectic cells is obtained in hypereutectic irons, as the result of nonequilibrium solidification following the concept of a coexisting region. Dendrites appear to be distributed between eutectic cells at higher eutectic undercooling, while in inoculated irons and for lower undercooling, the eutectic cells are "reinforced" by eutectic austenite dendrites. A Zr, Ca, Al-FeSi alloy appears to be an effective inoculant in low S, low Al, gray cast irons, especially for a late inoculation technique, with beneficial effects on both graphite and austenite phases. First, inoculation influenced the nucleation of graphite/eutectic cell, and then their characteristics. A further role of these active elements directly contributed to form nucleation sites for austenite, as complex (Mn,X)S particles.

  13. Electron theory study on the effect of Mn on as-cast structure of Fe-C-Cr-Mn cast irons

    Institute of Scientific and Technical Information of China (English)

    SUN Zhi-ping; SHEN Bao-luo; WANG Jun; LIU Hao-huai; YANG Hong-shan; HUANG Si-jiu

    2008-01-01

    The valence electron structure of alloying austenite of 3C-15Cr high chromium White cast iron with different Mn contents from 1%to 6% is analyzed by BLD method and EET.Results shoW that the addition of Mn has major influence on the valence electron structure of the alloying austenite,especially on that of Fe-C,Fe-C-Cr and Fe-C-Cr-Mn unit cells of it.The effect becomes weak when Mn content is over 4%.Based on the effect of nA,F Dc,the weighting of each unit cell and the degree of underceoling on phase transition of the austenite,we can calculate the retained austenite content of as-cast structure of the hish chromium white cast iron.The calculation results coincide well with those of the experiment.The phase transition characters of the austenite in high chromium white cast iron can be forecasted through valence electron structure analysis of alloying austenite by BLD method and EET on the basis of Fe-C-Cr equilibrium phase diagram.

  14. Numerical modelling of thin-walled hypereutectic ductile cast iron parts

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Hattel, Jesper Henri; Tiedje, Niels Skat

    2006-01-01

    Solidification of hypereutectic thin-walled ductile cast iron has been modelled in one dimension taking into account the precipitation of off-eutectic austenite dendrites during solidification. The simulations have been compared with casting experiments on plate geometries with plate thicknesses...

  15. TO SELECTION OF TECHNOLOGICAL SCHEME OF SOFTENING HEAT TREATMENT FOR HIGH CHROMIUM CAST IRON

    Directory of Open Access Journals (Sweden)

    V. G. Efremenko

    2014-03-01

    Full Text Available Purpose. High chromium cast irons with austenitic matrix have low machinability. The aim of work is search of new energy-saving modes of preliminary softening heat treatment enhancing the machinability of castings by forming an optimum microstructure. Methodology. Metallographic analysis, hardness testing and machinability testing are applied. Findings. It was found out that high temperature annealing with continuous cooling yields to martensite-austenite matrix in cast iron 270Х15Г2Н1MPhT, which abruptly affects the machinability of cast iron. Significant improvement of machinability is achieved by forming of structure "ferrite + granular carbides" and by decline of hardness to 37-39 HRC in the case of two-stage isothermal annealing in the subcritical temperature range or by the use of quenching and tempering (two-step or cyclic. Originality. It was found that the formation of the optimal structure of the matrix and achievement of desired hardness level needed for improving machinability of high chromium cast iron containing 3 % austenite-forming elements, can be obtained: 1 due to pearlite original austenite followed by spherodization eutectoid carbides, and 2 by getting predominantly martensite structure followed by the decay of martensite and carbides coagulation at high-temperature tempering. Practical value. The new energy-saving schemes of softening heat treatment to ensure the growth of machinability of high chromium cast iron, alloyed by higher quantity of austenite forming elements, are proposed.

  16. Residual stress studies of austenitic and ferritic steels

    International Nuclear Information System (INIS)

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

  17. Early detection of damage in austenitic materials under thermocyclic stress

    International Nuclear Information System (INIS)

    Austenitic pipe systems in nuclear power plants are subject to thermomechanical stress. Temperature gradients resulting from alternating cold and warm fluids in the pipelines lead to stress gradients, especially in the surge line, lines of the volume control and aftercooling system, and spray lines. The thermomechanical stress induces microstructural changes and fatigue of the pipeline material. The project focused on the development of new, nondestructive sensor systems and concepts for detecting and interprating fatigue-induced microstructural changes prior to crack initiation. In a joint research project of IZFP (Fraunhofer Institute of Non-Destructive Test Methods) and the WKK (Materials Science Department) of TU Kaiserslautern University, thermo-elastic/plastic load states of an austenitic pipeline steel were investigated systematically in fatigue tests. Conventional and nondestructive in-situ characterisation of the fatigue characteristics were applied to find an early detection concept for selective component monitoring in the context of pro-active ageing management.

  18. Urinary casts

    Science.gov (United States)

    ... necrosis , viral disease (such as CMV nephritis ), and kidney transplant rejection . Waxy casts can be found in people with advanced kidney disease and chronic kidney failure . White blood cell ( ...

  19. Hair casts

    Directory of Open Access Journals (Sweden)

    Sweta S Parmar

    2014-01-01

    Full Text Available Hair casts or pseudonits are circumferential concretions,which cover the hair shaft in such a way that, it could be easily removed. They are thin, cylindrical, and elongated in length. We present an unusual case of an 8-year-old girl presenting with hair casts. Occurrence of these is unusual, and they may have varied associations. This patient was suffering from developmental delay. It is commonly misdiagnosed as and very important to differentiate from pediculosis capitis.

  20. Improved cast stainless steels for shield module applications

    International Nuclear Information System (INIS)

    Full text of publication follows: Casting of austenitic stainless steels offers the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the divertor cassette for the International Tokamak Experimental Reactor (ITER). Casting offers major cost savings when compared to fabrication via welding together quarter modules machined from large forgings. However, because of the large grain size, low dislocation density and extensive segregation of alloying elements, the strength properties of such cast components are frequently inferior to those of conventionally forged and annealed components. To improve and validate cast stainless steel as a substitute for wrought stainless steel for shield module applications, a series of test cast steels based on the commercially available CF3M specification have been designed and fabricated. These modifications utilize combinations of Mn and N,which are expected to synergistically result in significant increases in strength. In addition, two other alloys will enhance solid solution strengthening with Cu and W additions to increase strength. It will be necessary to demonstrate that these compositional modifications do not adversely affect performance in the ITER water corrosion and radiation environments Computational thermodynamics and solidification modeling predict that these improved cast steel compositions to be fully austenitic throughout the solidification process. Post-cast heat treatments are a second-route for improving strength and properties of cast materials. Homogenizing treatments to remove second particles have also been explored as means of improving strength in cast stainless steel. In this paper, the physical metallurgy, mechanical properties, and irradiation tolerance of the improved cast stainless steel compositions and heat treatments will be compared to standard cast stainless steel. Fracture toughness, weldability, and non-destructive analysis of

  1. Colour Metallography of Cast Iron - Chapter 3: Spheroidal Graphite Cast Iron (Ⅰ

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2010-02-01

    Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour

  2. Colour Metallography of Cast Iron - Chapter 4: Vermicular Graphite Cast Iron (Ⅱ

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2011-05-01

    Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour

  3. Colour Metallography of Cast Iron - Chapter 3: Spheroidal Graphite Cast Iron (Ⅳ

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2010-11-01

    Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour

  4. Spinodal decomposition of austenite in long-term-aged duplex stainless steel

    International Nuclear Information System (INIS)

    Spinodal decomposition of austenite phase in the cast duplex stainless steels CF-8 and -8M grades has been observed after long- term thermal aging at 400 and 350/degree/C for 30,000 h (3.4 yr). At 320/degree/C, the reaction was observed only at the limited region near the austenite grain boundaries. Ni segregation and ''worm-holes'' corresponding to the spatial microchemical fluctuations have been confirmed. The decomposition was observed only for heats containing relatively high overall Ni content (9.6--12.0 wt %) but not in low-Ni (8.0--9.4 wt %) heats. In some specimens showing a relatively advanced stage of decomposition, localized regions of austenite with a Vickers hardness of 340--430 were observed. However, the effect of austenite decomposition on the overall material toughness appears secondary for aging up to 3--5 yr in comparison with the effect of the faster spinodal decomposition in ferrite phase. The observation of the thermally driven spinodal decomposition of the austenite phase in cast duplex stainless steels validates the proposition that a miscibility gap occurs in Fe-Ni and ancillary systems. 16 refs., 7 figs., 1 tab

  5. Experimental data on seismic response of piping

    International Nuclear Information System (INIS)

    Displacement-controlled, sinusoidal vibration tests were performed on one-inch to four-inch diameter pipe segments. Straight pipe segments; straight pipe with a local reduced wall thickness; double spans; pipe segments with back-to-back flanges, socket welds, and elbows were tested at the Berkeley Nuclear Laboratories. Test results demonstrate that, within the limits of the test parameters, pipe spans will not collapse at extreme levels of dynamic loading. Extreme, in this case, means input levels as much as 16 times the Section III Level D allowable of 3 Sm or 2Sy. Material ductility limits the response to levels such that the fatigue damage from one seismic event of ten equivalent maximum stress cycles should be insignificant if the pressure is limited to the design pressure of 2/3 Sy. The cyclic life of austenitic pipe is superior to that of carbon steel. The fundamental frequency of the pipe span has a significant effect on pipe response. The lower the frequency, the greater the acceleration response at the same input acceleration. The lowest frequency tested was 5 Hz. Dramatic levels of material dynamic strain hardening were noted

  6. Solidification and casting

    CERN Document Server

    Cantor, Brian

    2002-01-01

    INDUSTRIAL PERSPECTIVEDirect chillcasting of aluminium alloysContinuous casting of aluminium alloysContinuous casting of steelsCastings in the automotive industryCast aluminium-silicon piston alloysMODELLING AND SIMULATIONModelling direct chill castingMold filling simulation of die castingThe ten casting rulesGrain selection in single crystal superalloy castingsDefects in aluminium shape castingPattern formation during solidificationPeritectic solidificationSTRUCTURE AND DEFECTSHetergeneous nucleation in aluminium alloysCo

  7. Nitrogen bearing austenitic stainless steels for surgical implants

    Energy Technology Data Exchange (ETDEWEB)

    Tschiptschin, A.P.; Aidar, C.H.; Alonso-Falleiros, N. [Sao Paulo Univ. (Brazil). Escola Politecnica; Neto, F.B. [Instituto de Pesquisas Tecnologicas, Sao Paulo (Brazil)

    1999-07-01

    Nitrogen addition promotes substantial improvements on general and localized corrosion performance of stainless steels. In recent times high nitrogen (up to 0.6 wt%) and Mn bearing super austenitic stainless steel has been studied for medical applications due to its low Ni content, the so called body friendly alloys. 18%Cr, 0.4%N and 15%Mn stainless steels were cast either from electrolytic or commercial master alloys in induction furnace, forged, solubilized at 1423K for 3 hours and water quenched. Delta ferrite and carbide precipitate free structures were observed. (orig.)

  8. Effect of long-term thermal aging on the mechanical properties of casting duplex stainless steels

    International Nuclear Information System (INIS)

    Highlights: ► The micro-hardness change tendency of ferrite and austenite by aging was studied. ► Embrittlement behavior of Z3CN20-09M CDSSs by aging was investigated by SP test. ► The crack propagation energy Wt − Wiu slightly changes with the thermal aging time. ► Spinodal decomposition and spinodally coarsening take place in ferrite by aging. ► Z3CN20-09M CDSSs become embrittlement after long-term thermal aging treatment. - Abstract: Casting duplex stainless steels (CDSSs) used for pressurized water reactor (PWR) pipes are susceptible to thermal aging brittleness during long-term service at its working temperature from 288 °C to 327 °C. In order to investigate its thermal aging behavior, Z3CN20-09M CDSSs have been thermally aged at 400 °C up to 15,000 h. The micro-hardness of austenite and ferrite phases, conventional tensile properties, impact properties and SPT properties at different aging duration have been measured. The results show that the micro-hardness in ferrite gradually increases with increase of long thermal aging time, while the effect of the long aging time on the micro-hardness in austenite is negligible. The tensile strength and yield strength progressively and slightly increase with the long aging time, respectively. The impact property test confirms that there is the same change tendency as the percentage of elongation which decreases with the long aging time. The changes of SPT ultimate strength, SPT yield strength and SPT specific fracture energy by aging individually show that there is an almost same tendency as the tensile strength, the yield strength and the percentage of elongation with the thermal aging time. All above the mechanical properties changes of Z3CN20-09M CDSSs are associated with the changes of the dislocation configurations in austenite, the precipitation of G-phase on the dislocation line and in ferrite phase, the spinodal decomposition and the coarsening of the spinodally decomposed structure in ferrite

  9. Abrasion Resistance of as-Cast High-Chromium Cast Iron

    Directory of Open Access Journals (Sweden)

    Pokusová Marcela

    2014-12-01

    Full Text Available High chromium cast irons are widely used as abrasion resistant materials. Their properties and wear resistance depend on carbides and on the nature of the matrix supporting these carbides. The paper presents test results of irons which contain (in wt.% 18-22 Cr and 2-5 C, and is alloyed by 1.7 Mo + 5 Ni + 2 Mn to improve the toughness. Tests showed as-cast irons with mostly austenitic matrix achieved hardness 36-53 HRC but their relative abrasion-resistance was higher than the tool steel STN 19436 heat treated on hardness 60 HRC.

  10. Steel castings Ultrasonic examination, Part 2: Steel castings for highly stressed components

    CERN Document Server

    International Organization for Standardization. Geneva

    2004-01-01

    This European Standard specifies the requirements for the ultrasonic examination of steel castings (with ferritic structure) for highly stressed components and the methods for determining internal discontinuities by the pulse echo technique. This European Standard applies to the ultrasonic examination of steel castings which have usually received a grain refining heat treatment and which have wall thicknesses up to and including 600 mm. For greater wall thicknesses, special agreements apply with respect to test procedure and recording levels. This European Standard does not apply to austenitic steels and joint welds.

  11. Predictions for fatigue crack growth life of cracked pipes and pipe welds using RMS SIF approach and experimental validation

    International Nuclear Information System (INIS)

    The objective of the present study is to understand the fatigue crack growth behavior in austenitic stainless steel pipes and pipe welds by carrying out analysis/predictions and experiments. The Paris law has been used for the prediction of fatigue crack growth life. To carry out the analysis, Paris constants have been determined for pipe (base) and pipe weld materials by using Compact Tension (CT) specimens machined from the actual pipe/pipe weld. Analyses have been carried out to predict the fatigue crack growth life of the austenitic stainless steel pipes/pipes welds having part through cracks on the outer surface. In the analyses, Stress Intensity Factors (K) have been evaluated through two different schemes. The first scheme considers the 'K' evaluations at two points of the crack front i.e. maximum crack depth and crack tip at the outer surface. The second scheme accounts for the area averaged root mean square stress intensity factor (KRMS) at deepest and surface points. Crack growth and the crack shape with loading cycles have been evaluated. In order to validate the analytical procedure/results, experiments have been carried out on full scale pipe and pipe welds with part through circumferential crack. Fatigue crack growth life evaluated using both schemes have been compared with experimental results. Use of stress intensity factor (KRMS) evaluated using second scheme gives better fatigue crack growth life prediction compared to that of first scheme. Fatigue crack growth in pipe weld (Gas Tungsten Arc Welding) can be predicted well using Paris constants of base material but prediction is non-conservative for pipe weld (Shielded Metal Arc Welding). Further, predictions using fatigue crack growth rate curve of ASME produces conservative results for pipe and GTAW pipe welds and comparable results for SMAW pipe welds. - Highlights: → Predicting fatigue crack growth of Austenitic Stainless Steel pipes and pipe welds. → Use of RMS-SIF and local SIF at maximum

  12. Microstructure and Mechanical Properties of ADI Depending on Austenitization Methods and Parameters

    OpenAIRE

    T. Giętka; T. Szykowny

    2012-01-01

    Ductile iron was quenched using two-variant isothermal transformation. The first treatment variant consisted of one-phase austenitization at a temperature t = 830, 860 or 900 C, cooling down to an isothermal transformation temperature of 300 or 400 C and holding from 8 to 64 minutes. The second treatment variant consisted of two-phase austenitization. Cast iron was austenitizied at a tem- perature t = 950 C and cooled down to a supercritical temperature t ’ = 900, 860 or 830 C. Isothermal tra...

  13. Mechanism of silicon influence on the chill of cast iron

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2007-12-01

    Full Text Available In this work an analytical solution of general validity is used to explain mechanism of the silicon influence on the absolute chill tendency (CT and chill (w of cast iron. It is found that CT can be related to nucleation potential of graphite (Nv, growth parameter (μ of eutectic cells, temperature range (ΔTsc and the pre-eutectic austenite volume fraction (fγ. It has been shown that silicon additions: a impede the growth of graphite eutectic cells, μ, b expands the temperature range ΔTsc, c increases the nucleation potential of graphite Nv, d lowers the pre-eutectic austenite volume fraction, fγ. and in consequence the absolute chilling tendency, CT decreases. The minimum wall thicknesses for chilled castings, or chill widths (w in wedge shaped castings is related to CT and as silcon contents increases, the w value also increases.

  14. Effect of austempering parameters on microstructure and mechanical properties of horizontal continuous casting ductile iron dense bars

    Directory of Open Access Journals (Sweden)

    Chun-jie Xu

    2015-03-01

    Full Text Available In the present research, the orthogonal experiment was carried out to investigate the influence of different austempering process parameters (i.e. austenitizing temperature and time, and austempering temperature and time on microstructure and mechanical properties of LZQT500-7 ductile iron dense bars with 172 mm in diameter which were produced by horizontal continuous casting (HCC. The results show that the major factors influencing the hardness of austempered ductile iron (ADI are austenitizing temperature and austempering temperature. The fraction of retained austenite increases as the austenitizing and austempering temperatures increase. When austenitizing temperature is low, acicular ferrite and retained austenite can be efficiently obtained by appropriately extending the austenitizing time. The proper austmepering time could ensure enough stability of retained austenite and prevent high carbon austenite decomposition. The optimal mechanical properties of ADI can be achieved with the following process parameters: austenitizing temperature and time are 866 °C and 135 min, and austempering temperature and time are 279 °C and 135 min, respectively. The microstructure of ADI under the optimal austempering process consists of fine acicular ferrite and a small amount of retained austenite, and the hardness, tensile strength, yield strength, elongation and impact toughness of the bars are HBW 476, 1670 MPa, 1428 MPa, 2.93% and 25.7 J, respectively.

  15. Development status of ultrasonic test techniques for cast stainless steel

    International Nuclear Information System (INIS)

    Ultrasonic testing has been thought to be difficult to apply to cast stainless steel which is used as the material for the main coolant pipes in pressurized water reactors (PWRs). An ultrasonic testing technique using large aperture twin crystal transducers was developed in INSS for application to inspection of the main coolant pipes. The method was evaluated in an application to detect circumferential and axial defects in the cast stainless steel pipes. It was found that (1) the defects could be detected which had a depth that was so small that their evaluation was not required; and (2) depth sizing and length sizing of detected defects were also possible. (author)

  16. Cast construction elements for heat treatment furnaces

    Directory of Open Access Journals (Sweden)

    B. Piekarski

    2011-07-01

    Full Text Available The study presents sketches and photos of the cast creep-resistant components used in various types of heat treatment furnaces. The shape of the elements results from the type of the operation carried out in the furnace, while dimensions are adjusted to the size of the furnace working chamber. The castings are mainly made from the high-alloyed, austenitic chromium-nickel or nickel-chromium steel, selecting the grade in accordance with the furnace operating conditions described by the rated temperature, the type and parameters of the applied operating atmosphere, and the charge weight. Typical examples in this family of construction elements are: crucibles, roller tracks, radiant tubes and guides. The majority of castings are produced in sand moulds.

  17. Thin wall ductile and austempered iron castings

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2010-07-01

    Full Text Available It has been shown that it is possible to produce thin wall castings made of ductile iron with wall thickness in the range of 1.2 to 2.9 mm(without chills, cold laps and misruns. Thin wall ductile iron castings can be lighter (380 g than their substitutes made of aluminium alloys (580g. The kinetics of austenitising transformation was studied in unalloyed ductile iron. The advance of transformations during austenitising was monitored by measurement the fraction of martensite and also by dilatometic studies. It has been shown that in thin wall ductile iron castings austenitising at 880 oC for 20 minutes is adequate to obtain the austenite matrix at the end of the first stage of austempering heat treatment cycle.

  18. Solar axion search with the CAST experiment

    CERN Document Server

    Arik, E; Autiero, D; Barth, K; Belov, A; Beltrán, B; Borghi, S; Boydag, F S; Bräuninger, H; Cantatore, G; Carmona, J M; Cetin, S A; Collar, J I; Dafni, T; Davenport, M; Di Lella, L; Dogan, O B; Eleftheriadis, C; Elias, N; Fanourakis, G K; Ferrer-Ribas, E; Fischer, H; Franz, J; Galan, J; Gazis, E; Geralis, T; Giomataris, Yu; Gninenko, S; Gomez, H; Hasinoff, M; Heinsius, F H; Hikmet, I; Hoffmann, D H H; Irastorza, I G; Jacoby, J; Jakovcic, K; Kang, D; Karageorgopoulou, T; Karuza, M; Königsmann, K C; Kotthaus, R; Krcmar, M; Kousouris, K; Kuster, M; Lakic, B; Lasseur, C; Liolios, A; Ljubcici, A; Lozza, V; Lutz, G; Luzón, G; Miller, D; Morales, J; Niinikoski, T; Nordt, A; Ortiz, A; Papaevangelou, T; Pivovaroff, M; Placci, A; Raiteri, G; Raffelt, G; Riege, H; Rodríguez, A; Ruz, J; Savvidis, I; Semertzidis, Y; Serpico, P; Solanki, S K; Soufli, R; Stewart, L; Tsagri, M; Van Bibber, K; Villar, J; Vogel, J; Walckiers, L; Zioutas, K

    2008-01-01

    The CAST (CERN Axion Solar Telescope) experiment is searching for solar axions by their conversion into photons inside the magnet pipe of an LHC dipole. The analysis of the data recorded during the first phase of the experiment with vacuum in the magnet pipes has resulted in the most restrictive experimental limit on the coupling constant of axions to photons. In the second phase, CAST is operating with a buffer gas inside the magnet pipes in order to extent the sensitivity of the experiment to higher axion masses. We will present the first results on the $^4{He}$ data taking as well as the system upgrades that have been operated in the last year in order to adapt the experiment for the $^3{He}$ data taking. Expected sensitivities on the coupling constant of axions to photons will be given for the recent $^3{He}$ run just started in March 2008.

  19. Mechanical Properties of Thermally Aged Austenitic Stainless Steel Welds and Cast Austenitic Stainless Steel

    International Nuclear Information System (INIS)

    Conventional test methods for tensile and J-R properties of such weld require large size specimens. Meanwhile, small punch (SP) test has advantages of using small size samples at specific location. In this study, the mechanical property changes caused by the thermal aging were evaluated for the stainless steel welds and CASSs using tensile, J-R, and SP test. Based on the results, correlations were developed to estimate the fracture toughness using the load-displacement curve of SP tests. Finally, the fracture surfaces of compact tension (CT) and SP test specimens are compared and discussed in view of the effect of thermal aging on microstructure. Stainless steel welds of ER316L and ER347 as well as CASS (CF8M) were thermally aged at 400 .deg. C for 5,000 h. So far, tensile properties and fracture toughness of un-aged materials were carried out at room temperature and 320 .deg. C as a reference data. In order to evaluate the effect of thermal aging on mechanical properties, aged specimens are being tested and the changes in these properties will be discussed. In addition, correlations will be developed to estimate the fracture toughness in between J-R curve and SP curve

  20. Cast iron with spherical graphite is a perspective material for NPP equipment manufacture

    International Nuclear Information System (INIS)

    High-plasticity austenitic and ferritic spheroidal graphite cast irons are designed. The ferritic spheroidal graphite cast iron is shown to have a high fracture toughness after additional recrystallization heat treatment. The nodular cast iron is noted to show promise for components operating under irradiation. Domestic experience of production of ferritic and austenitic nodular cast irons of high fracture toughness permits to cast any complex-shaped components. This fact in combination with good workability gives the possibility of decreasing the number of labour consuming operations in manufacturing as spent fuel storage and shipping casks so other components of NPPs. The nodular irons are recommended to be used instead of steel 00Kh13NDP and 0Kh18N9T forgings

  1. Austenite formation during intercritical annealing

    Directory of Open Access Journals (Sweden)

    A. Lis

    2008-07-01

    Full Text Available Purpose: of this paper is the effect of the soft annealing of initial microstructure of the 6Mn16 steel on the kinetics of the austenite formation during next intercritical annealing.Design/methodology/approach: Analytical TEM point analysis with EDAX system attached to Philips CM20 was used to evaluate the concentration of Mn, Ni and Cr in the microstructure constituents of the multiphase steel and mainly Bainite- Martensite islands.Findings: The increase in soft annealing time from 1-60 hours at 625°C increases Mn partitioning between ferrite and cementite and new formed austenite and decreases the rate of the austenite formation during next intercritical annealing in the (α+γ temperature range at 700 and 750°C. The general equations for carbide dissolution and austenite formation in intercritical temperature range were established.Research limitations/implications: The final multiphase microstructure can be optimised by changing the time / temperature parameters of the intercritical heating in the (α+γ temperature range.Originality/value: The knowledge of partitioning of alloying elements mainly Mn during soft annealing and intercritical heating is very important to optimise the processing technology of intercritical annealing for a given amount of the austenite.

  2. Heat pipes

    CERN Document Server

    Dunn, Peter D

    1994-01-01

    It is approximately 10 years since the Third Edition of Heat Pipes was published and the text is now established as the standard work on the subject. This new edition has been extensively updated, with revisions to most chapters. The introduction of new working fluids and extended life test data have been taken into account in chapter 3. A number of new types of heat pipes have become popular, and others have proved less effective. This is reflected in the contents of chapter 5. Heat pipes are employed in a wide range of applications, including electronics cooling, diecasting and injection mo

  3. Uniaxial Fatigue of HDPE-100 Pipe. Experimental Analysis

    OpenAIRE

    Djebli, A.; A. Aid; M. Bendouba; Talha, A.; Benseddiq, N.; M. Benguediab; S. Zengah

    2014-01-01

    In this paper, an experimental analysis for determining the fatigue strength of PE-100, one of the most used High Density Polyethylene (HDPE) materials for pipes, under cyclic axial loadings is presented. HDPE is a thermoplastic material used for piping systems, such as natural gas distribution systems, sewer systems and cold water systems, which provides a good alternative to metals such as cast iron or carbon steel. One of the causes for failures of HDPE pipes is fatigue which is the result...

  4. Effect of casting technology on microstructure and phases of high carbon high speed steel

    Directory of Open Access Journals (Sweden)

    Zhang Tianming

    2011-05-01

    Full Text Available The as-cast microstructures of high carbon high speed steels (HC-HSS made by sand casting, centrifugal casting and electromagnetic centrifugal casting, respectively, were studied by using of optical microscopy (OM and D/max2200pc X-ray diffraction. The results show that the microstructure of as-cast HC-HSS is dominated by alloy carbides (W2C, VC, Cr7C3, martensite and austenite. The centrifugal casting and electromagnetic centrifugal casting apparently improve the solidification structure of HC-HSS. With the increase of magnetic intensity (B, the volume fraction of austenite in the HC-HSS solidification structure increases significantly while the eutectic ledeburite decreases. Moreover, the secondary carbides precipitated from the austenite are finer with more homogeneous distribution in the electromagnetic centrifugal castings. It has also been found that the lath of eutectic carbide in ledeburite becomes finer and carbide phase spacing in eutectic ledeburite increases along with the higher magnetic field strength.

  5. Eutectic solidification mode of spheroidal graphite cast iron and graphitization

    Directory of Open Access Journals (Sweden)

    Hideo Nakae

    2007-02-01

    Full Text Available The shrinkage and chilling tendency of spheroidal graphite (abbreviated SG cast iron is much greater than that of the flake graphite cast iron in spite of its higher amount of C and Si contents. Why? The main reason should be the difference in their graphitization during the eutectic solidification. In this paper, we discuss the difference in the solidification mechanism of both cast irons for solving these problems using unidirectional solidification and the cooling curves of the spheroidal graphite cast iron. The eutectic solidification rate of the SG cast iron is controlled by the diffusion of carbon through the austenite shell, and the final thickness is 1.4 times the radius of the SG, therefore, the reduction of the SG size, namely, the increase in the number, is the main solution of these problems.

  6. Study on the microstructure and mechanical properties of medium carbon Cr-Si-Mn-Mo-V steel for cast inserted dies

    OpenAIRE

    Hao, Xiao-Yan; LI Guo-lu; LIU Jin-hai

    2005-01-01

    The microstructure and mechanical properties of cast inserted dies for automobile covering components were studied. The results show that the as-cast microstructures of cast inserted dies are composed of pearlite, martensite,bainite, and austenite; and that the annealed microstructure is granular pearlite. The mechanical properties of cast inserted dies approach that of forged inserted dies. The tensile strength is 855 MPa, the elongation is 16%, the impact toughness is 177 J/cm2, and the har...

  7. Surface modification of investment cast-316L implants: microstructure effects.

    Science.gov (United States)

    El-Hadad, Shimaa; Khalifa, Waleed; Nofal, Adel

    2015-03-01

    Artificial femur stem of 316L stainless steel was fabricated by investment casting using vacuum induction melting. Different surface treatments: mechanical polishing, thermal oxidation and immersion in alkaline solution were applied. Thicker hydroxyapatite (HAP) layer was formed in the furnace-oxidized samples as compared to the mechanically polished ones. The alkaline treatment enhanced the precipitation of HAP on the samples. It was also observed that the HAP precipitation responded differently to the different phases of the microstructure. The austenite phase was observed to have more homogeneous and smoother layer of HAP. In addition, the growth of HAP was sometimes favored on the austenite phase rather than on ferrite phase. PMID:25579929

  8. In-Situ Austenite Steel Matrix Composite Reinforced by Granular γ+(Fe,Mn)3C Eutectic

    Institute of Scientific and Technical Information of China (English)

    LIANG Gao-fei; XU Zhen-ming; JIANG Qi-chuan; LI Jian-guo

    2004-01-01

    A new in-situ austenite matrix composite reinforced by granular γ+(Fe, Mn)3C binary eutectics (abbreviated to in-situ AMGE) was prepared in as-cast state, in which the modifier, yttrium-based heavy rare earth alloy, was used to influence carbon segregation, manganese segregation and phase formation. The eutectics are formed in the molten pools among austenite dendrites at the later stage of non-equilibrium solidification because the modifier enhances carbon segregation and manganese segregation greatly. Pin-on-disc dry wear tests show that the wear resistance of in-situ AMGE is 1-3 times higher than that of austenite medium manganese steel under low and medium loads, and the loads under which serious wear of in-situ AMGE occurs are much higher than that of austenite medium manganese steel.

  9. Transformation Behavior and Microstructure in a 40Cr2Ni2MoV Cast Steel

    Institute of Scientific and Technical Information of China (English)

    Cheng Liu; Zhenbo Zhao; Sanjiwan. D. Bhole1; Derek O. Northwood

    2004-01-01

    The transformation behavior of a 40Cr2Ni2MoV cast steel manufactured by electroslag remelting (ESR) has been investigated. Compared to a forged steel, the incubation periods for both the pearlite and bainite transformations are shorter, but the transformation times are longer. The austenite is easier to transform into martensite. Optical microscopy and TEM indicated that there were variations in microstructure during the super-cooled austenite transformation. This is attributed to an inhomogeneous austenite, resulting from the segregation of elements during the ESR solidification.

  10. Investigation on ductile fracture behavior of 3-inch diameter Type 304 stainless steel pipe with a circumferential through-wall crack

    International Nuclear Information System (INIS)

    At Japan Atomic Energy Research Institute (JAERI), a pipe fracture test program has been conducted as a part of the Leak-Before-Break (LBB) verification research in LWR pressure boundary pipings. In this program, fracture behavior and fracture criteria of the circumferentially cracked pipe have been investigated, using austenitic stainless steel pipes and carbon steel pipes. This report presents a four-point bending test results of 3-inch diameter Type 304 austenitic stainless steel pipes with circumferential through-wall crack at room temperature. Pipe fracture data were obtained from the test in regard to load-loadline displacement, crack extension, crack opening area, and so on. Discussions are performed on the effect of pipe ovalization ratio at maximum load, the application of the net-section collapse criterion, and the effect of initial crack angle, wall-thickness etc. on J-R curve. Furthermore, the crack opening area was estimated by assuming a simple crack model. (author)

  11. Nodular cast iron and casting monitoring

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2008-10-01

    Full Text Available In this paper quality monitoring of nodular cast iron and casting made of it is presented. A control system of initial liquid cast iron to spheroidization, after spheroidization and inoculation with using of TDA method was shown. An application of an ultrasonic method to assessment of the graphite form and the metal matrix microstructure of castings was investigated.

  12. High temperature corrosion of cast irons and cast steels in dry air

    Energy Technology Data Exchange (ETDEWEB)

    Tholence, F.; Norell, M. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Engineering Metals

    2001-07-01

    The oxidation in dry air of four cast alloys intended for exhaust gas systems has been examined. Particular interest was directed to how the oxide growth was related to the microstructures. The examined alloys were two cast ductile irons, a SiMo alloy (Fe3,86Si0,6Mo3C) and a Ni-Resist alloy (Fe32Ni5,3Si2,1C), and two cast stainless steels, one ferritic (Fe18Cr2,1Mn0,32C) and one austenitic (Fe20Cr9Ni0,47C). Coupons were oxidised for 50 h at temperatures between 650 C and 1050 C. The samples were characterised by using XRD, SEM/EDX and AES. As expected, the overall oxide thickness increased with temperature and partial spallation occurred at the highest temperatures for all alloys. Porous Fe oxide nodules nucleate at the graphite nodules on the ductile irons. These Fe-oxide nodules formed above a continuous layer of Fe-Si-oxide for the SiMo and mixed Fe-Ni-Si oxides for the Ni-Resist. The total oxide thickness is about (60 {mu}m). Thick oxides at the interdendritic regions in the cast steels were attributed to non-Cr-carbides. Segregation of Cr directed the formation of iron oxide nodules to the centre of the dendrites in the austenitic alloy. (orig.)

  13. Examination of overlay repaired BWR pipe joints

    International Nuclear Information System (INIS)

    Intergranular stress corrosion cracking (IGSCC) in a large number of austenitic stainless steel girth welds in boiling water reactor (BWR) piping has prompted the development of the weld overlay for repair (WOR) as a short-term remedy. It is necessary to examine the deposited overlay weld material for adequate definition of its condition and to monitor the overlaid IGSCC to determine if it grows past the bounds assumed in the design of the repair. This paper reports on NDE techniques evaluated using weld overlaid pipe samples containing known defects, overlaid samples removed from BWR service, and overlaid weld joints in plant. These samples included overlays containing fabrication defects and overlaid pipes containing deep and shallow laboratory- and service-induced IGSCC

  14. Systematic Microstructural and Corrosion Performance Evaluation of CK-3MCuN and CN-3MN High Molybdenum Stainless Steel Castings

    Energy Technology Data Exchange (ETDEWEB)

    C.D. Lundin; S. Wen; W. Liu; G. Zhou

    2001-10-01

    High molybdenum austenitic stainless steel castings are widely accepted for their high strength, excellent weldability, and good corrosion resistance over a wide range of temperatures in highly oxidizing aqueous and gaseous media in chemical processing and other environments. With their desirable performance, high molybdenum austenitic stainless steel castings are increasingly applied in industry in a similar manner as wrought materials. In general, cast and wrought stainless and high alloy steels are anticipated to possess equivalent resistance to corrosive media, and they are frequently used in conjunction with each other. However, alloying element segregation usually is more evident in castings than in wrought counterparts. Segregation of alloying elements can lead to the formation of secondary phases, such as sigma. Mechanical properties and especially the corrosion resistance of castings may be affected by the secondary phases. In addition, improper heat treatment procedures c an also lead to the formation of carbides and secondary phases in high alloy and austenitic stainless steels.

  15. Transformation of austenite to duplex austenite-ferrite assembly in annealed stainless steel 316L consolidated by laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Saeidi, K.; Gao, X. [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden); Lofaj, F. [Institute of Materials Research of the Slovak Academy of Sciences, Watsonova 47, Košice (Slovakia); Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 916 24 Trnava (Slovakia); Kvetková, L. [Institute of Materials Research of the Slovak Academy of Sciences, Watsonova 47, Košice (Slovakia); Shen, Z.J. [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden)

    2015-06-05

    Highlights: • Mechanical properties, phase and microstructure stability of laser melted steel was studied. • Duplex austenite-ferrite assembly with improved mechanical properties was formed. • Dissolution of Mo in the steel matrix resulted in ferrite stabilization and stress relief. • Enhanced mechanical properties were achieved compared to conventionally casted and annealed steel. - Abstract: Laser melting (LM), with a focused Nd:YAG laser beam, was used to form solid bodies from 316L austenite stainless steel powder and the laser melted samples were heat treated at various temperatures. The phase changes in heat treated samples were characterized using X-ray diffraction (XRD). Samples heat treated at 800 °C and 900 °C remained single austenite while in samples heat treated at 1100 °C and 1400 °C a dual austenite-ferrite phase assembly was formed. The ferrite formation was further verified by electron back scattering diffraction (EBSD) and selective area diffraction (SAD). Microstructural changes were studied by scanning and transmission electron microscopy (SEM, TEM). In samples heat treated up to 900 °C, coalescence of the cellular-sub grains was noticed, whereas in sample heat treated at and above 1100 °C the formation of ferrite phase was observed. The correlation between the microstructure/phase assembly and the measured strength/microhardness were investigated, which indicated that the tensile strength of the laser melted material was significantly higher than that of the conventional 316L steel even after heat treatment whereas caution has to be taken when laser melted material will be exposed to an application temperature above 900 °C.

  16. Transformation of austenite to duplex austenite-ferrite assembly in annealed stainless steel 316L consolidated by laser melting

    International Nuclear Information System (INIS)

    Highlights: • Mechanical properties, phase and microstructure stability of laser melted steel was studied. • Duplex austenite-ferrite assembly with improved mechanical properties was formed. • Dissolution of Mo in the steel matrix resulted in ferrite stabilization and stress relief. • Enhanced mechanical properties were achieved compared to conventionally casted and annealed steel. - Abstract: Laser melting (LM), with a focused Nd:YAG laser beam, was used to form solid bodies from 316L austenite stainless steel powder and the laser melted samples were heat treated at various temperatures. The phase changes in heat treated samples were characterized using X-ray diffraction (XRD). Samples heat treated at 800 °C and 900 °C remained single austenite while in samples heat treated at 1100 °C and 1400 °C a dual austenite-ferrite phase assembly was formed. The ferrite formation was further verified by electron back scattering diffraction (EBSD) and selective area diffraction (SAD). Microstructural changes were studied by scanning and transmission electron microscopy (SEM, TEM). In samples heat treated up to 900 °C, coalescence of the cellular-sub grains was noticed, whereas in sample heat treated at and above 1100 °C the formation of ferrite phase was observed. The correlation between the microstructure/phase assembly and the measured strength/microhardness were investigated, which indicated that the tensile strength of the laser melted material was significantly higher than that of the conventional 316L steel even after heat treatment whereas caution has to be taken when laser melted material will be exposed to an application temperature above 900 °C

  17. Crack growth rates and fracture toughness of irradiated austenitic stainless steels in BWR environments.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Shack, W. J.

    2008-01-21

    In light water reactors, austenitic stainless steels (SSs) are used extensively as structural alloys in reactor core internal components because of their high strength, ductility, and fracture toughness. However, exposure to high levels of neutron irradiation for extended periods degrades the fracture properties of these steels by changing the material microstructure (e.g., radiation hardening) and microchemistry (e.g., radiation-induced segregation). Experimental data are presented on the fracture toughness and crack growth rates (CGRs) of wrought and cast austenitic SSs, including weld heat-affected-zone materials, that were irradiated to fluence levels as high as {approx} 2x 10{sup 21} n/cm{sup 2} (E > 1 MeV) ({approx} 3 dpa) in a light water reactor at 288-300 C. The results are compared with the data available in the literature. The effects of material composition, irradiation dose, and water chemistry on CGRs under cyclic and stress corrosion cracking conditions were determined. A superposition model was used to represent the cyclic CGRs of austenitic SSs. The effects of neutron irradiation on the fracture toughness of these steels, as well as the effects of material and irradiation conditions and test temperature, have been evaluated. A fracture toughness trend curve that bounds the existing data has been defined. The synergistic effects of thermal and radiation embrittlement of cast austenitic SS internal components have also been evaluated.

  18. Effect of annealing on mechanical properties of ledeburitic cast steel

    Directory of Open Access Journals (Sweden)

    E. Rożniata

    2007-01-01

    Full Text Available Purpose: The paper presents evaluation of influence of grain normalization (refinement as a result of repeatedaustenitizing, and the inclination to precipitate the hypereutectoid cementite in Widmannstätten structure inG200CrMoNi4-6-3 cast steel. Four temperatures of heat refining have been applied.Design/methodology/approach: Basic research of G200CrMoNi4-6-3 cast steel included metallographicanalysis, and hardness and impact strength tests. The heat treatment has been planned on the basis of CCTdiagram prepared for that alloy cast steel.Findings: The test material has been G200CrMoNi4-6-3 hypereutectoid cast steel. The evaluation has beencarried out for four annealing temperatures, i.e. 850°C, 900°C, 950°C and 1050°C. At all annealing temperaturesin the structure of cast steel the precipitation of hypereutectoid cementite along grain boundaries of formeraustenite took place. At the temperature of 850°C one may observe the coagulated hypereutectoid cementiteprecipitates inside of primary grains of austenite. Whereas beginning from the temperature of 900°C thecementite in G200CrMoNi4-6-3 cast steel forms distinct „subgrains” inside of primary grains of austenite.Research limitations/implications: Research financed by the Ministry of Scientific Research and InformationTechnology, grant No. 3 T08B 057 29.Practical implications: G200CrMoNi4-6-3 cast steel of ledeburite class is used mainly for rolls production.Any data related to the structure and mechanical properties of that cast steel are precious for the manufacturersand users of the mill rolls.Originality/value: The new heat treatment of G200CrMoNi4-6-3 cast steel

  19. Remote controlled in-pipe manipulators for dye-penetrant inspection and grinding of weld roots inside of pipes

    International Nuclear Information System (INIS)

    Technical plants which have to satisfy stringent safety criteria must be continuously kept in line with the state of art. This applies in particular to nuclear power plants. The quality of piping in nuclear power plants has been improved quite considerably in recent years. By virtue of the very high quality requirements fulfilled in the manufacture of medium-carrying and pressure-retaining piping, one of the focal aspects of in-service inspections is the medium wetted inside of the piping. A remote controlled pipe crawler has been developed to allow to perform dye penetrant testing of weld roots inside piping (ID ≥ 150 mm). The light crawler has been designed such that it can be inserted into the piping via valves (gate valves, check valves,...) with their internals removed. Once in the piping, all crawler movements are remotely controlled (horizontal and vertical pipes incl. the elbows). If indications are found these discontinuities are ground according to a qualified procedure using a special grinding head attached to the crawler with complete extraction of all grinding residues. The in-pipe grinding is a special qualified three (3) step performance that ensures no residual tensile stress (less than 50 N/mm2) in the finish machined austenitic material surface. The in-pipe inspection system, qualified according to both the specifications of the German Nuclear Safety Standards Commission (KTA) and the American Society of Mechanical Engineers (ASME), has already been used successfully in nuclear power plants on many occasions. (author)

  20. Influences of copper on solidification structure and hardening behavior of high chromium cast irons

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; XIONG Ji; FAN Hong-yuan; SHEN Bao-luo; GAO Sheng-ji

    2008-01-01

    The influences of copper on microstructure and the hardening behavior of high chromium cast irons subjected to sub-critical treatment were investigated.The results show that the mierostructure of the as-cast high chromium cast irons consists of retained austenite,martensite and M7 C3 type eutectic carbide.When copper is added into high chromium cast irons,austenite and carbide contents are increased.The increased addition of copper content from 0%to 1.84%leads to the increase of austenite and carbide from 15.9%and 20.0% to 61.0%and 35.5%,respectively.In the process of sub-critical treatment,the retained austenite in the matrix can be precipitated into secondary carbides and then transforms into martensite in cooling process,which causes the secondary hardening of the alloy under sub-critical treatment.High chromium cast irons containing copper in sub-critical treatment appear the second hardening curve peak due to the precipitation of copper from supersaturated matrix.

  1. Influence of thermal aging on primary water stress corrosion cracking of cast duplex stainless steel (second report). Consideration on fractography after slow strain rate technique

    International Nuclear Information System (INIS)

    In order to evaluate the stress corrosion cracking (SCC) susceptibility of cast duplex stainless steel which is used for the main coolant pipe of pressurized water reactors (PWRs), the slow strain rate technique (SSRT) and the constant load test (CLT) of the materials were performed in simulated primary water at 360degC. The cast duplex stainless steel contains ferrite phase with ranging from 8 to 23% and its mechanical properties are affected by long time thermal aging. Therefore, we paid attention to the influence of its ferrite content and thermal aging on the SCC susceptibility of this unaged and aged stainless steel and prepared three kinds of specimen with different ferrite contents (23%, 15% and 8%). The brittle fracture of the unaged specimens after SSRT mainly consists of quasi-cleavage fracture in austenitic phase. After aging, it changes to a mixture of quasi-cleavage fracture in both austenitic and ferritic phases. Microcracks were observed on the unaged specimen surfaces and aged ones for 10,000 hours at 400degC after about 10,000 hours of the CLT under the load condition of 1.2∼2.0 times of yield strength. The crack initiation sites of CLT specimens are similar to SSRT fracture surfaces. The SCC susceptibility of this 23% ferrite material increases with aging time at 400degC. The SCC susceptibility of 15% and 23% ferrite materials are higher than that of 8% ferrite material with aging condition for 30,000h at 400degC. (author)

  2. Effect of Chemical Composition on Number of Eutectic Colonies in Ni-Mn-Cu Cast Iron

    Directory of Open Access Journals (Sweden)

    A. Janus

    2013-01-01

    Full Text Available Determined were direction and intensity of influence of alloying additions on the number of eutectic graphite colonies in austenitic cast iron Ni-Mn-Cu. Chemical composition of the cast iron was 1.7 to 3.3% C, 1.4 to 3.1% Si, 2.8 to 9.9% Ni, 0.4 to 7.7% Mn, 0 to 4.6% Cu,0.14 to 0.16% P and 0.03 to 0.04% S. Analysed were structures of mottled (20 castings and grey (20 castings cast iron. Obtained wereregression equations determining influence intensity of individual components on the number of graphite colonies per 1 cm2 (LK. It wasfound that, in spite of high total content of alloying elements in the examined cast iron, the element that mainly decides the LK value is carbon, like in a plain cast iron.

  3. Heat Pipes

    Science.gov (United States)

    1996-01-01

    Heat Pipes were originally developed by NASA and the Los Alamos Scientific Laboratory during the 1960s to dissipate excessive heat build- up in critical areas of spacecraft and maintain even temperatures of satellites. Heat pipes are tubular devices where a working fluid alternately evaporates and condenses, transferring heat from one region of the tube to another. KONA Corporation refined and applied the same technology to solve complex heating requirements of hot runner systems in injection molds. KONA Hot Runner Systems are used throughout the plastics industry for products ranging in size from tiny medical devices to large single cavity automobile bumpers and instrument panels.

  4. An approach to prior austenite reconstruction

    International Nuclear Information System (INIS)

    One area of interest in Friction Stir Welding (FSW) of steels is to understand microstructural evolution during the process. Most of the deformation occurs in the austenite temperature range. Quantitative microstructural measurements of prior austenite microstructure are needed in order to understand evolution of the microstructure. Considering the fact that room temperature microstructure in ferritic steels contains very little to no retained austenite, prior austenite microstructure needs to be recovered from the room temperature ferrite. In this paper, an approach based on Electron Backscattered Diffraction (EBSD) is introduced to detect Bain zones. Bain zone detection is used to reconstruct prior austenite grain structure. Additionally, a separate approach based on phase transformation orientation relationships is introduced in order to recover prior austenite orientation. - Highlights: ►This approach provides a tool to reconstruct large-scale austenite microstructures. ► It recovers prior austenite orientation without relying on retained austenite. ► It utilizes EBSD data from the room temperature microstructure. ► Higher number of active variants leads to more accurate reconstructions. ► At least two variants are needed in order to recover prior austenite orientation.

  5. Piping inspection round robin

    International Nuclear Information System (INIS)

    The piping inspection round robin was conducted in 1981 at the Pacific Northwest National Laboratory (PNNL) to quantify the capability of ultrasonics for inservice inspection and to address some aspects of reliability for this type of nondestructive evaluation (NDE). The round robin measured the crack detection capabilities of seven field inspection teams who employed procedures that met or exceeded the 1977 edition through the 1978 addenda of the American Society of Mechanical Engineers (ASME) Section 11 Code requirements. Three different types of materials were employed in the study (cast stainless steel, clad ferritic, and wrought stainless steel), and two different types of flaws were implanted into the specimens (intergranular stress corrosion cracks (IGSCCs) and thermal fatigue cracks (TFCs)). When considering near-side inspection, far-side inspection, and false call rate, the overall performance was found to be best in clad ferritic, less effective in wrought stainless steel and the worst in cast stainless steel. Depth sizing performance showed little correlation with the true crack depths

  6. Colour Metallography of Cast Iron - Chapter 1: Introduction (Ⅰ

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2009-02-01

    Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour

  7. Application of evolutionary algorithm for cast iron latent heat identification

    Directory of Open Access Journals (Sweden)

    J. Mendakiewicz

    2008-12-01

    Full Text Available In the paper the cast iron latent heat in the form of two components corresponding to the solidification of austenite and eutectic phases is assumed. The aim of investigations is to estimate the values of austenite and eutectic latent heats on the basis of cooling curve at the central point of the casting domain. This cooling curve has been obtained both on the basis of direct problem solution as well as from the experiment. To solve such inverse problem the evolutionary algorithm (EA has been applied. The numerical computations have been done using the finite element method by means of commercial software MSC MARC/MENTAT. In the final part of the paper the examples of identification are shown.

  8. Manufacture of centrifugal Castings

    OpenAIRE

    Minář, Martin

    2015-01-01

    The main goal of this bachelor thesis is to collect basic information related to the production of castings by centrifugal casting. It is focused on horizontal and vertical centrigugal casting, casting of various metals and their alloys, such as zinc, aluminum, iron, steel and silumin. This technology is compared with other casting methods in terms of specific characteristics, amount of usage, production economics, advantages, disadvantages, the resulting quality of castings and other factors.

  9. The UK Casting Industry

    Institute of Scientific and Technical Information of China (English)

    Jincheng Liu

    2006-01-01

    The casting production in the UK in 2004 is presented and analysed. The UK casting industry has played an important role in world casting and manufacturing production. However recent years the rapid development of some developing countries has been shifting the casting production from the western industrialized countries including the UK. The UK casting industry and associated research and technology organizations, universities have been working together very hard to face the serious competition to make the UK casting industry have a sustainable future. The UK casting industry remains strong and plays an important role in world casting and manufacturing production.

  10. Ultrasonic inspection of austenitic welds

    International Nuclear Information System (INIS)

    The metallurgical structure of austenitic welds is described and contrasted with that found in ferritic welds. It is shown that this structure imparts a marked elastic anisotropy in the ultrasonic propagation parameters. Measurements of variations in the apparent attenuation of sound and deviations in the beam direction are described. The measurements are interpreted in terms of the measured velocity anisotropy. Two applications of the fundamental work are described. In the first it is shown how, by using short pulse compression wave probes, and with major modification of the welding procedure, a stainless steel fillet weld in an AGR boiler can be inspected. In the second application, alternative designs of a transition butt weld have been compared for ease of ultrasonic inspection. The effects of two different welding processes on such an inspection are described. Finally, the paper examines the prospects for future development of inspection and defect-sizing techniques for austenitic welds. (author)

  11. Identification of scale formed on Cr-Ni cast steel

    Directory of Open Access Journals (Sweden)

    B. Kalandyk

    2010-10-01

    Full Text Available An attempt has been made to identify the scale formed on austenitic chromium-nickel cast steel with additions of Ti and Zr duringoxidising at temperatures of 820 and 1000 °C. The scale identification was done by the technique of scanning microscopy, by X-raydiffraction phase analysis in Bragg-Brentano geometry with constant angle of incidence, and by scratch test.

  12. CA Investment Casting Process of Complex Castings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    CA (Computer aided) investment casting technique used in superalloy castings of aerospace engine parts was presented. CA investment casting integrated computer application, RP (Rapid Prototyping) process, solidification simulation and investment casting process. It broke the bottle neck of making metal die. Solid model of complex parts were produced by UGII or other software, then translated into STL(Stereolithography) file, after RP process of SLS(Selective Laser Sintering), wax pattern used in investment ...

  13. Application of experimental data for numerical simulation of cast iron solidification

    Directory of Open Access Journals (Sweden)

    J. Mendakiewicz

    2008-12-01

    Full Text Available Numerical analysis of cast iron solidification process is presented. The system casting – shell mould is discussed. The parameter controlling the solidification process called a substitute thermal capacity (STC has been constructed in this way in order to take into account the evolution of latent heats connected with the solidification of austenite and eutectic phases. The information concerning the proper approximation of STC results from the experimental data using the thermal and derivative analysis (TDA.

  14. Numerical modelling of thin-walled hypereutectic ductile cast iron parts

    OpenAIRE

    Pedersen, Karl Martin; Hattel, Jesper Henri; Tiedje, Niels Skat

    2006-01-01

    Solidification of hypereutectic thin-walled ductile cast iron has been modelled in one dimension taking into account the precipitation of off-eutectic austenite dendrites during solidification. The simulations have been compared with casting experiments on plate geometries with plate thicknesses from 2.8 to 8.0 mm with good agreement for both cooling curves and nodule counts. The experimental results revealed that the eutectic solidification of plates with thicknesses less than 4.3 mm was cha...

  15. Developments in austenitic steels containing manganese

    International Nuclear Information System (INIS)

    Two broad categories of austenitic steels are considered in this review: (a) alloys based on the Fe-Mn-C system, typified by austenitic wear resistant (Hadfield) steels and (b) alloys based on the Fe-Mn-Cr system, typified by austenitic corrosion resistant steels. Advances made in recent years in understanding and improving the relevant properties and manufacturing methods of these steels are critically appraised. The development of austenitic manganese bearing high technology steels for fusion reactor and other non-magnetic applications, as well as those that can be used in cryogenic structures, is also considered. (author)

  16. The ancient Chinese casting techniques

    OpenAIRE

    Tan Derui; Lian Haiping

    2011-01-01

    In the course of Chinese civilization, which lasted more than 5,000 years, casting production has made a huge contribution. In this paper, some representative metal castings were presented. According to their forming techniques, they can be grouped into stone mould casting, clay mould casting, ablation casting, lost wax casting, stack casting, permanent mould casting, sand casting, etc. According to their materials, they can be categorized into tin bronze, bimetallic bronze, malleable cast ir...

  17. Special thermite cast irons

    OpenAIRE

    Yu. Zhiguts; I. Kurytnik

    2008-01-01

    The given paper deals with the problems of the synthesis of cast iron by metallothermy synthesis. On the basis of investigated method of calculations structures of charges have been arranged and cast iron has been synthesized further. Peculiarities metallothermic smelting were found, mechanical properties and structure of received cast iron were investigated and different technologies for cast iron receiving were worked out.

  18. Thin Wall Iron Castings

    Energy Technology Data Exchange (ETDEWEB)

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

    2001-10-31

    Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

  19. Numerical modeling of coupled heat transfer and phase transformation for solidification of the gray cast iron

    DEFF Research Database (Denmark)

    Jabbari, Masoud; Hosseinzadeh, Azin

    2013-01-01

    In the present study the numerical model in 2D is used to study the solidification bahavior of the gray cast iron. The conventional heat transfer is coupled with the proposed micro-model to predict the amount of different phases, i.e. total austenite (c) phase, graphite (G) and cementite (C), in...

  20. Thermal deformation behavior and microstructure of nuclear austenitic stainless steel

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Gleeble-1500D thermal simulation tester was employed in the hot-compression investigation of as-cast nuclear 304 austenitic stainless steel under conditions: deformation temperature 950―1200℃; deformations 30% and 50%; deformation rates 0.01 and 0.1 s?1. The results show that the flow stress decreases with temperature rise under the same strain rate and deformation, that the flow stress increases with deformation under the same temperature and strain rate, and that the flow stress increases with strain rate under the same temperature condition, i.e., work hardening becomes distinct. Materials exhibit better strength-toughness when the strain rate is 0.01 s-1, the deformation is 50%, and the temperature is 1050℃.

  1. Solidification of cast iron - A study on the effect of microalloy elements on cast iron

    DEFF Research Database (Denmark)

    Moumeni, Elham

    of the austenite, in the last region to solidify. The superfine graphite which forms in this type of irons is short (10-20µm) and stubby. The microstructure of this kind of graphite flakes in titanium alloyed cast iron is studied using electron microscopy techniques. The methods to prepare samples of...... the unetched, colour-etched and deep-etched samples. It was confirmed that in irons with high sulphur content (0.12 wt%) nucleation of type-A and type-D graphite occurs on Mn sulphides that have a core of complex Al, Ca, Mg oxide. An increased titanium level of 0.35% produced superfine interdendritic...

  2. Measurement of residual stresses in weld overlay pipe component

    International Nuclear Information System (INIS)

    Weld overlay is one of the improvement methods for austenitic stainless steel suffered intergranular stress corrosion cracking (IGSCC). The weld overlay itself increases the wall thickness and change the stress field from inner to outer surface of pipes. To insure the improvement of the stress field on the pipe after weld overlay, the stress distribution of 10 inches pipes weld overlay mock up specimens were insured in this study. The strain-gage hole-drilling method and FEM analysis were applied to measure and calculate the residual stress along the pipe wall thickness. The results show that it behaves good agreement on the residual stress from the measurement and calculation. The weld overlay also induces a compressive stress field on the inner wall, whereas the tensile stress field is created on the outer wall surface. The mechanical grinding on the weld overlay surface will affect the residual stress distribution about 0.04 inches in depth. (author)

  3. Mechanical characterization of microconstituents in a cast duplex stainless steel by micropillar compression

    International Nuclear Information System (INIS)

    The mechanical properties of individual constituent in a cast austenitic–ferritic stainless steel were studied using uniaxial micropillar compression tests. The results of compression tests of the micropillars with the diameter ranging from 1 to 5 and 1 to 10 µm for ferrite and austenite, respectively, reveal that the strength of both austenite and ferrite increases with a decrease in sample size. The compression results also confirm that the strength of ferrite phase is higher than the austenite. The average yield stress value of ferrite is approximately 200 MPa higher than that of the austenite phase with the same sample size. The critical resolved shear stress (CRSS) was also calculated based on pillar compression and electron backscatter diffraction (EBSD) results

  4. SPHERICAL MICROSTRUCTURE FORMATION OF THE SEMI-SOLID HIGH CHROMIUM CAST IRON Cr20Mo2

    Institute of Scientific and Technical Information of China (English)

    W.M. Mao; A.M. Zhao; X.Y. Zhong

    2004-01-01

    The nondendritic semi-solid slurry preparation of high chromium cast iron Cr20Mo2 has been studied in this paper. The experiments show that the proeutectic austenitic particles are more spherical under a larger stirring power condition, even if the stirring time is shorter, while the proeutectic austenitic particles are not very much spherical under a smaller stirring power condition and some proeutectic austenitic dendrites also exist, even if the stirring time is very long. The experiments also show that when stirred for 5 6 minutes under the test condition, the semi-solid slurry with 40vol. %-50vol. % solid fraction and spherical proeutectic austenite in the size of 50-80μm can be obtained.

  5. Chromium and copper influence on the nodular cast iron with carbides microstructure

    Directory of Open Access Journals (Sweden)

    G. Gumienny

    2010-10-01

    Full Text Available In this paper chromium to 1,00% and copper to 1,50% influence at constant molybdenum content of about 1,50% on the nodular cast ironwith carbides microstructure has been presented. It was found, that as a result of synergic addition of above-mentioned elements there isthe possibility obtaining an ausferrite in nodular cast iron with carbides castings. Conditions have been given, when in nodular cast iron with carbides at cooling at first in the form, then air-cooling austenite transformation to upper bainite, its mixture with lower bainite, martensite or ausferrite takes place. Transformations proceed during cooling and the crystallization of cast iron have been determined and the casting hardness has been presented.

  6. Improvement of austenitic Hadfield Mn-steel properties by thermomechanical processing

    International Nuclear Information System (INIS)

    A thermomechanical processing technique is used to improve austenitic Hadfield Mn-steel wear properties. ASTM A128 grade C steel billets were sized and multi-pass hot rolled. Rolling has been successfully carried out up to an 80% reduction in thickness on four passes in the temperature range 1200 to 800 oC. The inter-pass time ranged between 9 to 13 seconds. The steel was then solution treated at 900, 1000 and 1100 oC for 30 min. at temperature. Austenite grain size was measured and the carbide volume fraction was evaluated. The austenitic grains of the as-cast structure are surrounded by a network of carbides. The carbides have a lamellar structure and are richer in Cr and Mn than the austenitic grains. Austenitizing at 1100 oC was the optimum to dissolve the network of carbides. However, solution treatment at the higher temperature coarsens the austenite grains while decreasing the carbide volume fraction. By contrast, hot rolling creates finer grains and significantly reduces the carbide content. Furthermore, hot rolling followed by solution treatment further decreases the carbide content and distributes them homogeneously. This process has a positive effect on both the mechanical and wear properties. High reductions by hot rolling of the Hadfield steel creates both deformation bands and a twinned structure. These twinning boundaries are considered as slip obstacles to provide strengthening. A thick sheet martensitic structure is created accompanying twinning. Moreover, solution treatment of the hot deformed steel leads to the formation of a thin martensitic structure. (author)

  7. Phase transformations of under-cooled austenite of new bainitic materials for scissors crossovers

    Directory of Open Access Journals (Sweden)

    J. Pacyna

    2008-07-01

    Full Text Available The paper contains CCT diagrams presenting a transformation kinetics of under-cooled austenite from two new bainitic cast steels which the scissors crossovers for heavy-duty railway tracks (min. 230kN/axle at the speed up to 200 km/h are made of. The cooling ranges of UIC60 type railway tracks plot on the CCT diagrams indicate that there is a 100% bainitic structure in the scissors crossovers made of these cast steels as well, but mainly it would be a favourable for cracking resistance lower bainite. The achievable hardness of scissors crossovers made of new materials make it possible to use high–temperature tempering resulting in obtaining of good crack resistance. However one should provide a good quality of castings made.

  8. Measurements of the radioactive inventory of the old effluent pipe line on the BNL site

    International Nuclear Information System (INIS)

    When Berkeley Nuclear Laboratory (BNL) was built, a 3 inch cast iron pipe was laid to carry the radioactive effluent from the BNL effluent treatment plant to the power station for further treatment and/or discharge. In 1980/81 a new pipe line was installed and since then the old line has remained unused. As part of the refurbishment of certain parts of the BNL site currently in progress, the majority of the pipe is to be dug up in two stages, although a small length of the pipe which runs under existing foundations will be left in the ground. This report gives the radioactive inventory of the pipe based on measurements made during the first state of removal. Samples from the trench dug to expose the pipe were taken before and after the removal of the pipe and analysed to determine whether the pipe had leaked and the level of contamination caused by the pipe's removal. (author)

  9. Fatigue crack propagation in welded joint of austenitic steel for nuclear power engineering

    International Nuclear Information System (INIS)

    The crack propagation characteristics were obtained for Cr-Ni type austenitic steel 08Kh18N10T under variable stress in the individual zones of a welded joint on a pipe. Measurements of the threshold deviation of the stress intensity factor, ΔKp, showed that the root zone of the pipe welded joint was the weakest point as concerns crack propagation. The threshold values obtained for the filler metal on the pipe outer surface were considerably greater than those for the root zone of the welded joint and slightly greater than those for the base material and for the transition between the joint and the base material. The measured propagation response showed that the rate of fatigue crack propagation was for the base material higher by up to one order for low ΔK than for the filler joint and the root zone of the joint. (J.B.). 5 figs., 3 tabs., 6 refs

  10. Expanded austenite, crystallography and residual stress

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Hummelshøj, Thomas Strabo; Somers, Marcel A. J.

    2010-01-01

    The identity of expanded austenite as developing during low temperature nitriding and/or carburising of austenitic stainless steel has been under debate since the very first observation of this phase. In the present article, recent results obtained with (a) homogeneous samples of various uniform ...

  11. Expanded austenite; crystallography and residual stress

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Hummelshøj, Thomas Strabo; Somers, Marcel A. J.

    2009-01-01

    The identity of expanded austenite as developing during low temperature nitriding and/or carburizing of austenitic stainless steel has been under debate since the very first observation of this phase. In the present article recent results obtained with i) homogeneous samples of various uniform co...

  12. Expanded austenite; crystallography and residual stress

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Hummelshøj, Thomas Strabo; Somers, Marcel A. J.

    The identity of expanded austenite as developing during low temperature nitriding and/or carburizing of austenitic stainless steel has been under debate since the very first observation of this phase. In the present article recent results obtained with i) homogeneous samples of various uniform co...

  13. Effect of cooling rate and forced convection on as-cast structure of 2205 duplex stainless steel

    OpenAIRE

    Cheng Zhang; Hong-gang Zhong; Cong-sen Wu

    2015-01-01

    To forecast the as-cast structure and ferrite-austenite phase ratio of 2205 duplex stainless steel (DSS), the effects of cooling rate and forced convection were observed in a high-vacuum resistance furnace in which the forced convection was created by the rotation of the crucible. The as-cast structure of all 2205 DSS samples is full equiaxed grains, and the microstructure consists of a great amount of desirable intra-granular austenite inside the continuous ferrite grain matrix, besides Widm...

  14. Unusually well preserved casts of halite crystals: A case from the Upper Frasnian of northern Lithuania

    Science.gov (United States)

    Rychliński, Tomasz; Jaglarz, Piotr; Uchman, Alfred; Vainorius, Julius

    2014-07-01

    Upper Frasnian carbonate-siliciclastics of the Stipinai Formation (northern Lithuania) comprise a bed of calcareous silty arenite with casts of halite crystals, including hopper crystals. Unusually well-preserved casts occur on the lower surface of the bed, while poorly-preserved casts are present on the upper bedding surface. The casts originated as the result of the dissolution of halite crystals which grew in the sediment. The dissolution took place during early stages of diagenesis, when host sediment was soft. Unstable cavities after crystal dissolution were filled by overlying sediment forming their casts. The collapsing sediment form sink-hole deformation structures which disturb wave-ripple cross lamination from the upper part of the bed. Dewatering pipe structures are also present. The casts and accompanying sink-hole and dewatering pipes are classified as the postdepositional deformation structures caused by haloturbation.

  15. Heat pipes

    CERN Document Server

    Dunn, Peter D

    1982-01-01

    A comprehensive, up-to-date coverage of the theory, design and manufacture of heat pipes and their applications. This latest edition has been thoroughly revised, up-dated and expanded to give an in-depth coverage of the new developments in the field. Significant new material has been added to all the chapters and the applications section has been totally rewritten to ensure that topical and important applications are appropriately emphasised. The bibliography has been considerably enlarged to incorporate much valuable new information. Thus readers of the previous edition, which has established

  16. STUDY OF ELECTROMAGNETIC STIRRING REFINING MICRO- STRUCTURES OF PIPE-LINE STEEL SAW DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    Y. Zhang; B.N. Qian; X.M. Guo

    2002-01-01

    The effects of electromagnetic stirring on the microstructures of pipe-line steel SAWdeposited metal were investigated. The results showed that electromagnetic stirringincreased the number density of inclusions with 0.2-0.6μm in diameter and promotedthe formation and refining of acicular ferrite within austenite grains. The low tem-perature toughness of deposited metal was improved.

  17. High Mn austenitic stainless steel

    Science.gov (United States)

    Yamamoto, Yukinori [Oak Ridge, TN; Santella, Michael L [Knoxville, TN; Brady, Michael P [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Liu, Chain-tsuan [Knoxville, TN

    2010-07-13

    An austenitic stainless steel alloy includes, in weight percent: >4 to 15 Mn; 8 to 15 Ni; 14 to 16 Cr; 2.4 to 3 Al; 0.4 to 1 total of at least one of Nb and Ta; 0.05 to 0.2 C; 0.01 to 0.02 B; no more than 0.3 of combined Ti+V; up to 3 Mo; up to 3 Co; up to 1W; up to 3 Cu; up to 1 Si; up to 0.05 P; up to 1 total of at least one of Y, La, Ce, Hf, and Zr; less than 0.05 N; and base Fe, wherein the weight percent Fe is greater than the weight percent Ni, and wherein the alloy forms an external continuous scale including alumina, nanometer scale sized particles distributed throughout the microstructure, the particles including at least one of NbC and TaC, and a stable essentially single phase FCC austenitic matrix microstructure that is essentially delta-ferrite-free and essentially BCC-phase-free.

  18. Specialist meeting on leak before break in reactor piping and vessels

    Energy Technology Data Exchange (ETDEWEB)

    Bartholome, G.; Bazant, E.; Wellein, R. [Siemens KWU, Stuttgart (Germany)] [and others

    1997-04-01

    A series of research projects sponsored by the Federal Minister for Education, Science, Research and Technology, Bonn are summarized and compared to utility, manufacturer, and vendor tests. The purpose of the evaluation was to experimentally verify Leak-before-Break behavior, confirm the postulation of fracture preclusion for piping (straight pipe, bends and branches), and quantify the safety margin against massive failure. The results are applicable to safety assessment of ferritic and austenitic piping in primary and secondary nuclear power plant circuits. Moreover, because of the wide range of the test parameters, they are also important for the design and assessment of piping in other technical plant. The test results provide justification for ruling out catastrophic fractures, even on pipes of dimensions corresponding to those of a main coolant pipe of a pressurized water reactor plant on the basis of a mechanical deterministic safety analysis in correspondence with the Basis Safety Concept (Principle of Fracture Exclusion).

  19. A Study on the Microstructures and Toughness of Fe-B Cast Alloy Containing Rare Earth

    Science.gov (United States)

    Yi, Dawei; Zhang, Zhiyun; Fu, Hanguang; Yang, Chengyan; Ma, Shengqiang; Li, Yefei

    2015-02-01

    This study investigates the effect of cerium on the microstructures, mechanical properties of medium carbon Fe-B cast alloy. The as-cast microstructure of Fe-B cast alloy consists of the eutectic boride, pearlite, and ferrite. Compared with the coarse eutectic borides in the unmodified alloy, the eutectic boride structures in the modified alloy are greatly refined. Cerium promotes the formation of Ce2O3 phase. Ce2O3 can act as effective heterogeneous nuclei of primary austenite, and refine austenite and boride. After heat treatment, the impact toughness of the modified alloy is higher than that of the unmodified alloy because there are more broken borides in the modified alloy. Meanwhile, the fracture mechanism of medium carbon Fe-B alloy is depicted and analyzed by using fractography.

  20. Load bearing capacity of degraded nuclear piping

    International Nuclear Information System (INIS)

    Integrity assessment of piping components with postulated cracks is important for safe and reliable operation of power plants. While various equations and methods are available for prediction of the load bearing capacity of pipes and elbows, it is very important to choose the correct equation and method whose predictions are consistent, safe but not too conservative with respect to the experimental results. Towards this goal, a comprehensive Component Integrity Assessment Program was initiated under a joint MPA-BARC collaborative program where a large number of austenitic and ferritic pipes and elbows of nominal diameter of 50-400 mm with various crack configurations and sizes were tested. These test results along with results of previous tests were analysed with various available limit load equations present and also with the R6 method. Based on the comparison of these test results and predictions, the correct equation and method are recommended to reliably predict the load bearing capacity of flawed pipes and elbows reliably. (authors)

  1. Development of space reactor core heat pipes

    International Nuclear Information System (INIS)

    The Space Power Advance Reactor (SPAR) core heat pupes are being developed to transport 15 kW of power at 1400 K. A straight, 2-m-long, 15.9-mm-diam heat pipe was fabricated of low-carbon arc-cast molybdenum and filled with sodium as the working fluid. This nonconcentric, annular, screen-tube-wick pipe was tested successfully at 16.1 kW at 1310 K, at which point a boiling limit was encountered. Follow-on work has produced an as yet untested heat pipe which has its wick centered in the evaporator by spacer wires to alleviate the boiling limit problem. A dual artery wick heat pipe is being fabricated to further improve on the boiling limit and increase redundancy. Because the heat pipe must bend around the radiation shield of the SPAR reactor, a series of bending experiments was performed. Promising results were achieved by filling the pipe completely with sodium and bending at 3650 K

  2. Mechanism of fatigue crack initiation in austenitic stainless steels in light water reactor environments

    International Nuclear Information System (INIS)

    This paper examines the mechanism of fatigue crack initiation in austenitic stainless steels (SSs) in light water reactor (LWR) coolant environments. The effects of key material and loading variables on the fatigue lives of wrought and cast austenitic SSs in air and LWR environments have been evaluated. The influence of reactor coolant environments on the formation and growth of fatigue cracks in polished smooth SS specimens is discussed. The results indicate that the fatigue lives of these steels are decreased primarily by the effects of the environment on the growth of cracks <200 μm and, to a lesser extent, on enhanced growth rates of longer cracks. The fracture morphology in the specimens has been characterized. Exploratory fatigue tests were conducted to study the effects of surface micropits or minor differences in the surface oxide on fatigue crack initiation. (author)

  3. Development of Low-Cost Austenitic Stainless Gas-Turbine and Diesel Engine Components with Enhanced High-Temperature Reliability

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, P.J.; Swindeman, R.W.; Browning, P.F. (Solar Turbines, Inc.); Frary, M.E. (Caterpillar, Inc.); Pollard, M.J.; Siebenaler, C.W.; McGreevy, T.E.

    2004-06-01

    In July of 1999, a Cooperative Research and Development Agreement (CRADA) was undertaken between Oak Ridge National Laboratory (ORNL) and Solar Turbines, Inc. and Caterpillar, Inc. (Caterpillar Technical Center) to evaluate commercial cast stainless steels for gas turbine engine and diesel engine exhaust component applications relative to the materials currently being used. If appropriate, the goal was to develop cast stainless steels with improved performance and reliability rather than switch to more costly cast Ni-based superalloys for upgraded performance. The gas-turbine components considered for the Mercury-50 engine were the combustor housing and end-cover, and the center-frame hot-plate, both made from commercial CF8C cast austenitic stainless steel (Fe-l9Cr-12Ni-Nb,C), which is generally limited to use at below 650 C. The advanced diesel engine components considered for truck applications (C10, C12, 3300 and 3400) were the exhaust manifold and turbocharger housing made from commercial high SiMo ductile cast iron with uses limited to 700-750 C or below. Shortly after the start of the CRADA, the turbine materials emphasis changed to wrought 347H stainless steel (hot-plate) and after some initial baseline tensile and creep testing, it was confirmed that this material was typical of those comprising the abundant database; and by 2000, the emphasis of the CRADA was primarily on diesel engine materials. For the diesel applications, commercial SiMo cast iron and standard cast CN12 austenitic stainless steel (Fe-25Cr-13Ni-Nb,C,N,S) baseline materials were obtained commercially. Tensile and creep testing from room temperature to 900 C showed the CN12 austenitic stainless steel to have far superior strength compared to SiMo cast iron above 550 C, together with outstanding oxidation resistance. However, aging at 850 C reduced room-temperature ductility of the standard CN12, and creep-rupture resistance at 850 C was less than expected, which triggered a focused

  4. Metallic Reinforcement of Direct Squeeze Die Casting Aluminum Alloys for Improved Strength and Fracture Resistance

    Energy Technology Data Exchange (ETDEWEB)

    D. Schwam: J.F. Wallace: Y. Zhu: J.W. Ki

    2004-10-01

    The utilization of aluminum die casting as enclosures where internal equipment is rotating inside of the casting and could fracture requires a strong housing to restrain the fractured parts. A typical example would be a supercharger. In case of a failure, unless adequately contained, fractured parts could injure people operating the equipment. A number of potential reinforcement materials were investigated. The initial work was conducted in sand molds to create experimental conditions that promote prolonged contact of the reinforcing material with molten aluminum. Bonding of Aluminum bronze, Cast iron, and Ni-resist inserts with various electroplated coatings and surface treatments were analyzed. Also toughening of A354 aluminum cast alloy by steel and stainless steel wire mesh with various conditions was analyzed. A practical approach to reinforcement of die cast aluminum components is to use a reinforcing steel preform. Such performs can be fabricated from steel wire mesh or perforated metal sheet by stamping or deep drawing. A hemispherical, dome shaped casting was selected in this investigation. A deep drawing die was used to fabricate the reinforcing performs. The tendency of aluminum cast enclosures to fracture could be significantly reduced by installing a wire mesh of austenitic stainless steel or a punched austenitic stainless steel sheet within the casting. The use of reinforcements made of austenitic stainless steel wire mesh or punched austenitic stainless steel sheet provided marked improvement in reducing the fragmentation of the casting. The best strengthening was obtained with austenitic stainless steel wire and with a punched stainless steel sheet without annealing this material. Somewhat lower results were obtained with the annealed punched stainless steel sheet. When the annealed 1020 steel wire mesh was used, the results were only slightly improved because of the lower mechanical properties of this unalloyed steel. The lowest results were

  5. Mathematical Model of the Processoof Pearlite Austenitization

    Directory of Open Access Journals (Sweden)

    Olejarczyk-Wożeńska I.

    2014-10-01

    Full Text Available The paper presents a mathematical model of the pearlite - austenite transformation. The description of this process uses the diffusion mechanism which takes place between the plates of ferrite and cementite (pearlite as well as austenite. The process of austenite growth was described by means of a system of differential equations solved with the use of the finite difference method. The developed model was implemented in the environment of Delphi 4. The proprietary program allows for the calculation of the rate and time of the transformation at an assumed temperature as well as to determine the TTT diagram for the assigned temperature range.

  6. Special thermite cast irons

    Directory of Open Access Journals (Sweden)

    Yu. Zhiguts

    2008-07-01

    Full Text Available The given paper deals with the problems of the synthesis of cast iron by metallothermy synthesis. On the basis of investigated method of calculations structures of charges have been arranged and cast iron has been synthesized further. Peculiarities metallothermic smelting were found, mechanical properties and structure of received cast iron were investigated and different technologies for cast iron receiving were worked out.

  7. Accumulation and modeling of particles in drinking water pipe fittings

    OpenAIRE

    K. Neilands; M. Bernats; J. Rubulis

    2012-01-01

    The effect of pipe fittings (mainly T-pieces) on particle accumulation in drinking water distribution networks were shown in this work. The online measurements of flow and turbidity for cast iron, polyethylene and polyvinyl chloride pipe sections were linked with analysis of pipe geometry. Up to 0.29 kg of the total amount mobilized in T-pieces ranging from DN 100/100–DN 250/250. The accumulated amount of particles in fittings was defined as J and introduced into ...

  8. Characteristics of Fe-28Mn-6Si-5Cr shape memory alloy produced by centrifugal casting

    International Nuclear Information System (INIS)

    Recent application of ferrous shape memory alloys, particularly Fe-Mn-Si alloys as pipe joints used for a tunnel driving technique in the field of civil engineering, requires efficient production of alloy pipes. Centrifugal casting is one of the efficient manufacturing techniques which can produce suitable sizes of pipes of approximately 4 to 14 inches in outside diameter. The mechanical properties of the centrifugally cast Fe-Mn-Si shape memory alloy were investigated to have 700 MPa in tensile strength and shape recovery of ∝3% of the initial deformation. The shape recovery achieved by the centrifugally cast materials proved to be comparable to that of the rolled materials. The TEM microstructure of the centrifugally cast materials deformed necessarily in the process of shape recovery reveals random distribution of ε (hcp) bands containing many dislocations inside, whereas the structure of the rolled materials shows ε phases containing fewer dislocations. (orig.)

  9. The influence of chromium on the pearlite-austenite transformation kinetics of the Fe–Cr–C ternary steels

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Lingnan; Liu, Yaohui, E-mail: liuyaohui2005@126.com; Liu, Jia' an; Song, Yulai; Li, Shasha; Zhang, Renhang; Li, Tuanjie; Liang, Yan

    2015-11-05

    The Fe–Cr–C ternary steels containing different contents of Cr were successfully cast and further processed in the lab. Differential scanning calorimetry (DSC), optical microscope (OM), and scanning electron microscope (SEM) were employed to investigate the transformation of the Fe–Cr–C ternary steels from pearlite to austenite. It is found that the values of Ac1 and Ac3 are raised with increase in the content of Cr. In addition, the information on the transformation kinetics was obtained from experiment results and the Johnson-Mehl-Avrami-Kolmogorov model (JMAK). The obtained austenitic transformation kinetic process has been described in three overlapping steps: site saturation nucleation, diffusion-controlled growth, and impingement correction. The pre-exponential factor for diffusion decreases firstly and then increases. The activation energy for diffusion increases with the Cr content. In addition, Cr strongly affects the effective diffusion distance, the austenite nucleation sites, and the carbon activity gradient during the austenitic transformation kinetic process. - Highlights: • The pearlite-austenite transformation kinetics is researched by DSC. • The transformation kinetics is analyzed by experiment results and the JMAK model. • The activation energy and the diffusion coefficient are discussed.

  10. Shield For Flexible Pipe

    Science.gov (United States)

    Ponton, Michael K.; Williford, Clifford B.; Lagen, Nicholas T.

    1995-01-01

    Cylindrical shield designed to fit around flexible pipe to protect nearby workers from injury and equipment from damage if pipe ruptures. Designed as pressure-relief device. Absorbs impact of debris ejected radially from broken flexible pipe. Also redirects flow of pressurized fluid escaping from broken pipe onto flow path allowing for relief of pressure while minimizing potential for harm.

  11. Ultrasonic inspection of austenitic welds

    International Nuclear Information System (INIS)

    The ultrasonic examination of austenitic stainless steel weld metal has always been regarded as a difficult proposition because of the large and variable ultrasonic attenuations and back scattering obtained from apparently similar weld deposits. The work to be described shows how the existence of a fibre texture within each weld deposit (as a result of epitaxial growth through successive weld beads) produces a systematic variation in the ultrasonic attenuation coefficient and the velocity of sound, depending upon the angle between the ultrasonic beam and the fibre axis. Development work has shown that it is possible to adjust the welding parameters to ensure that the crystallographic texture within each weld is compatible with improved ultrasonic transmission. The application of the results to the inspection of a specific weld in type 316 weld metal is described

  12. Caste and power

    DEFF Research Database (Denmark)

    Roy, Dayabati

    2011-01-01

    relations and caste identities have overarching dimensions in the day-to-day politics of the study villages. Though caste almost ceases to operate in relation to strict religious strictures, under economic compulsion the division of labour largely coincides with caste division. In the cultural...

  13. Fundamentals of piping design

    CERN Document Server

    Smith, Peter

    2013-01-01

    Written for the piping engineer and designer in the field, this two-part series helps to fill a void in piping literature,since the Rip Weaver books of the '90s were taken out of print at the advent of the Computer Aid Design(CAD) era. Technology may have changed, however the fundamentals of piping rules still apply in the digitalrepresentation of process piping systems. The Fundamentals of Piping Design is an introduction to the designof piping systems, various processes and the layout of pipe work connecting the major items of equipment forthe new hire, the engineering student and the vetera

  14. Comparisons of simplified method JS and finite element for cracked pipes under thermal and mechanical loading

    International Nuclear Information System (INIS)

    In order to estimate the value of the parameter J for cracks in pipes, a complete set of finite element computations was conducted in France by CEA. The axisymetrical crack is located in the inner wall of the pipe. The crack depth is one quarter or one eighth of the thickness. The pipe, in austenitic steel or in ferritic steel, is subjected to internal pressure, axial load and linear thermal gradient through the thickness. The finite element results of J were compared to those predicted by simplified method Js, introduced in the A 16 guide developed by CEA for fast breeder reactor. (orig.)

  15. Aging degradation of cast stainless steel

    International Nuclear Information System (INIS)

    A program is being conducted to investigate the significance of in-service embrittlement of cast-duplex stainless steels under light-water reactor operating conditions. Data from room-temperature Charpy-impact tests for several heats of cast stainless steel aged up to 10,000 h at 350, 400, and 4500C are presented and compared with results from other studies. Microstructures of cast-duplex stainless steels subjected to long-term aging either in the laboratory or in reactor service have been characterized. The results indicate that at least two processes contribute to the low-temperature embrittleent of duplex stainless steels, viz., weakening of the ferrite/austenite phase boundary by carbide precipitation and embrittlement of ferrite matrix by the formation of additional phases such as G-phase, Type X, or the α' phase. Carbide precipitation has a significant effect on the onset of embrittlement of CF-8 and -8M grades of stainless steels aged at 400 or 4500C. The existing correlations do not accurately represent the embrittlement behavior over the temperature range 300 to 4500C. 18 refs., 13 figs

  16. Aging degradation of cast stainless steel

    International Nuclear Information System (INIS)

    A program is being conducted to investigate the significance of in-service embrittlement of cast duplex stainless steels under light-water reactor operating conditions. Microstructures of cast materials subjected to long-term aging either in reactor service or in the laboratory have been characterized by TEM, SANS, and APFIM techniques. Two precipitate phases, i.e., the Cr-rich α' and Ni- and Si-rich G phase, have been identified in the ferrite matrix of the aged steels. The results indicate that the low-temperature embrittlement is primarily caused by α' precipitates which form by spinodal decomposition. The relative contribution of G phase to loss of toughness is now known. Microstructural data also indicate that weakening of ferrite/austenite phase boundary by carbide precipitates has a significant effect on the onset and extent of embrittlement of the high-carbon CF-8 and CF-8M grades of stainless steels, particularly after aging at 400 or 4500C. Data from Charpy-impact, tensile, and J-R curve tests for several heats of cast stainless steel aged up to 10,000 h at 350, 400, and 4500C are presented and correlated with the microstructural results. Thermal aging of the steels results in an increase in tensile strength and a decrease in impact energy, J/sub IC/, and tearing modulus. The fracture toughness results show good agreement with the Charpy-impact data. The effects of compositional and metallurgical variables on loss of toughness are discussed

  17. Aging degradation of cast stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O.K.; Chung, H.M.

    1985-10-01

    A program is being conducted to investigate the significance of in-service embrittlement of cast-duplex stainless steels under light-water reactor operating conditions. Data from room-temperature Charpy-impact tests for several heats of cast stainless steel aged up to 10,000 h at 350, 400, and 450/sup 0/C are presented and compared with results from other studies. Microstructures of cast-duplex stainless steels subjected to long-term aging either in the laboratory or in reactor service have been characterized. The results indicate that at least two processes contribute to the low-temperature embrittleent of duplex stainless steels, viz., weakening of the ferrite/austenite phase boundary by carbide precipitation and embrittlement of ferrite matrix by the formation of additional phases such as G-phase, Type X, or the ..cap alpha..' phase. Carbide precipitation has a significant effect on the onset of embrittlement of CF-8 and -8M grades of stainless steels aged at 400 or 450/sup 0/C. The existing correlations do not accurately represent the embrittlement behavior over the temperature range 300 to 450/sup 0/C. 18 refs., 13 figs.

  18. Weldments and castings for liquid helium service

    International Nuclear Information System (INIS)

    The FY 81 results of the NBS program to evaluate weldments and castings for liquid helium service are reviewed. The tensile properties and fracture toughness of a series of five CF8M castings with delta-ferrite contents ranging from 0 to 28% were measured at 4 K. Work is continuing on a study to relate metallographic observations of duplex austenite delta-ferrite microstructures to the deformation and fracture of stainless steel welds and castings. The fracture toughness and fatigue crack growth rates of a 25Mn-5Cr-1Ni alloy, plate and welds, were measured at 4 K. Two 316L stainless steel weldments were tested at 4 K in support of the LCP program. The elastic properties of 316L stainless steel welds have been related to the texture in the weldment. An improved method of ultrasonic testing of stainless steel weldments was conceived and demonstrated; the method uses electromagnetic acoustic transducers (EMATs) to inspect the weldments with horizontal shear (SH) waves that are inherently less sensitive to the anisotropy of stainless steel welds. The research planned for FY 82 is also described

  19. Stress Corrosion Cracking Behavior of Cast Stainless Steels

    International Nuclear Information System (INIS)

    Casting of austenitic stainless steels offers the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the diverter cassette for the ITER fusion reactor. Casting offers major cost savings when compared to fabrication via welding of quarter modules machined from large forgings. However, the strength properties of such cast components are typically considered inferior to those of conventionally forged and annealed components. To improve and validate cast stainless steel as a substitute for wrought stainless steel, a development and testing program was initiated, utilizing nitrogen and manganese additions to promote improved performance. This paper focuses on the response of the first set of developmental alloys to neutron-irradiation and susceptibility to stress corrosion cracking. These cast materials may also have applications for different components in light water reactors. Results showed that all steels exhibited irradiation-induced hardening and a corresponding drop in ductility, as expected, although there is still considerable ductility in the irradiated samples. The cast steels all exhibited reduced hardening in comparison to a wrought reference steels, which may be related to a larger grain size. Higher nitrogen contents did not negatively influence irradiation performance. Regarding stress corrosion cracking susceptibility, the large difference in grain size limits the comparison between wrought and cast materials, and inclusions in a reference and archive cast alloy tests complicate analysis of these samples. Results suggest that the irradiated archive heat was more susceptible to cracking than the modified alloys, which may be related to the more complex microstructure. Further, the results suggest that the modified cast steel is at least as SCC resistant as wrought 316LN. The beneficial effect of nitrogen on the mechanical properties of the alloys remains after irradiation and is not

  20. Piping and structural interaction

    OpenAIRE

    Tveit, Siv-Anni

    2015-01-01

    Structural and piping stress analyses are generally conducted separately in most of the situations. A pipe stress analysis is performed based on loads caused by pressure, temperature variations, weight of the pipe (with contents) and blast. The pipes are analysed for several load cases separated into different design types like sustained, expansion and occasional. Established practice in piping design and calculation does not specifically account for structural flexibility. It is assumed that...

  1. Assessment of cracked pipes in primary piping systems of PWR nuclear reactors

    International Nuclear Information System (INIS)

    Pipes related to the Primary System of Pressurized Water Reactors (PWR) are manufactured from high toughness austenitic and low alloy ferritic steels, which are resistant to the unstable growth of defects. A crack in a piping system should cause a leakage in a considerable rate allowing its identification, before its growth could cause a catastrophic rupture of the piping. This is the LBB (Leak Before Break) concept. An essential step in applying the LBB concept consists in the analysis of the stability of a postulated through wall crack in a specific piping system. The methods for the assessment of flawed components fabricated from ductile materials require the use of Elasto-Plastic Fracture Mechanics (EPFM). Considering that the use of numerical methods to apply the concepts of EPFM may be expensive and time consuming, the existence of the so called simplified methods for the assessment of flaws in piping are still considered of great relevance. In this work, some of the simplified methods, normalized procedures and criteria for the assessment of the ductile behavior of flawed components available in literature are described and evaluated. Aspects related to the selection of the material properties necessary for the application of these methods are also discussed. In a next .step, the methods are applied to determine the instability load in some piping configurations under bending and containing circumferential through wall cracks. Geometry and material variations are considered. The instability loads, obtained for these piping as the result of the application of the selected methods, are analyzed and compared among them and with some experimental results obtained from literature. The predictions done with the methods demonstrated that they provide consistent results, with good level of accuracy with regard to the determination of maximum loads. These methods are also applied to a specific Study Case. The obtained results are then analyzed in order to give

  2. The influence of reversion annealing behavior on the formation of nanograined structure in AISI 201L austenitic stainless steel through martensite treatment

    International Nuclear Information System (INIS)

    Highlights: → The martensite formation becomes saturated at εs = 0.5. → The smallest average grain size of 65 nm is achieved by annealing at 850 oC for 30 s. → The nanocrystalline 201L steel showed good combination of strength and elongation. → The rate of martensite reversion was very high for the primary annealing times. -- Abstract: Martensite treatment is one of the known thermo-mechanical processes that can be used for the grain refinement of metastable austenitic stainless steels. In this work, the martensite to austenite reversion behavior as well as its effect on the processing of nanocrystalline structure in an as-cast AISI 201L austenitic stainless steel was investigated. The as-cast specimens were first homogenized and then hot forged in order to prepare a suitable microstructure for the subsequent martensite treatment. The cold rolling was carried out to various reductions between 10% and 95% followed by annealing at temperature range of 750-900 oC for different times of 15-1800 s. The microstructure characterization was performed using optical and scanning electron microscopies, X-ray diffraction and Feritscope. Hardness measurements were also used for evaluating the mechanical properties of the experimental material. The results indicated that the specimen which was reversion-annealed at 850 oC for 30 s exhibited the smallest average austenite grain size of 65 nm with more than 86% austenite.

  3. Mechanical properties of phase constituents in selected grades of cast steel

    OpenAIRE

    M. Garbiak; Zubko, P.

    2011-01-01

    The nanoindentation measurements performed on three cast steels of 0.3C-30Ni-18Cr type with various content of niobium and titanium were carried out.Mechanical propertiesofthe main phaseconstituents of the alloys, such as austenite, MC and M23C6 type carbides, were determined and analysed. The values of hardness (H) and Young modulus (E) for the austenite matrix were similar within the tested alloys. Essential differences (H=12 ÷ 24 GPa; E = 250 ÷ 400 GPa) were found between the carbide phase...

  4. Effects of carbon and molybdenum on the microstructures of high chromium white cast irons

    International Nuclear Information System (INIS)

    The effects of 3 levels of carbon and 1.5% Mo addition on the solidification structures of a 15% chromium white cast iron were studied. The volume fraction of primary austenite and of eutectic carbides, as well as the number of carbide particles per unit length and the mean secondary dendrite arm spacing were measured. By means of thermal analysis, thermal arrest corresponding to the formation of the primary austenite and of the eutectic were determined. The increase in the carbon content and the addition of Mo led to lowering of the thermal arrests and to coarsening of the particles. (author)

  5. Microbial deterioration of materials - simulation, case histories and countermeasures for metallic materials: Pitting corrosion caused by microbiological activity at austenitic stainless pipes used for river water. Mikrobielle Werkstoffzerstoerung - Simulation, Schadensfaelle und Gegenmassnahmen fuer metallische Werkstoffe: Lochfrass an Flusswasser-Rohrleitungen aus hochlegierten austenitischen Staehlen durch mikrobielle Aktivitaet

    Energy Technology Data Exchange (ETDEWEB)

    Korkhaus, J. (BASF AG, Ludwigshafen am Rhein (Germany). Abt. Werkstofftechnik); Titz, J.T. (BASF AG, Ludwigshafen am Rhein (Germany). Abt. Werkstofftechnik); Wagner, G.H. (BASF AG, Ludwigshafen am Rhein (Germany). Abt. Werkstofftechnik)

    1994-02-01

    Rhine River water used for cooling purposes increasingly causes pitting at circumferential welds in type 321 and 616Ti stainless steel piping. Type 321 is attacked even at ambient temperature, type 316Ti at 35 to 55 C. At these temperatures both materials did not show pitting in the past. Failure analysis and corrosion tests, both in the laboratory and in a pilot plant (river water circuit), showed that the open circuit potential of stainless steels is shifted into a region of instable pitting resistance by a microbiological effect. Thus, pit nuclei are able to grow even at circumferential joints welded without any visible annealing colours. The actual concept to select cooling water pipe materials, therefore, has to be reconsidered. (orig.)

  6. ADIMEW: Fracture assessment and testing of an aged dissimilar metal weld pipe assembly

    International Nuclear Information System (INIS)

    ADIMEW (Assessment of Aged Piping Dissimilar Metal Weld Integrity) was a three-year collaborative research programme carried out under the EC 5th Framework Programme. The objective of the study was to advance the understanding of the behaviour and safety assessment of defects in dissimilar metal welds between pipes representative of those found in nuclear power plant. ADIMEW studied and compared different methods for predicting the behaviour of defects located near the fusion boundaries of dissimilar metal welds typically used to join sections of austenitic and ferritic piping operating at high temperature. Assessment of such defects is complicated by issues that include: severe mis-match of yield strength of the constituent parent and weld metals, strong gradients of material properties, the presence of welding residual stresses and mixed mode loading of the defect. The study includes the measurement of material properties and residual stresses, predictive engineering analysis and validation by means of a large-scale test. The particular component studied was a 453mm diameter pipe that joins a section of type A508 Class 3 ferritic pipe to a section of type 316L austenitic pipe by means of a type 308 austenitic weld with type 308/309L buttering laid on the ferritic pipe. A circumferential, surface-breaking defect was cut using electro discharge machining into the 308L/309L weld buttering layer parallel to the fusion line. The test pipe was subjected to four-point bending to promote ductile tearing of the defect. This paper presents the results of TWI contributions to ADIMEW including: fracture toughness testing, residual stress measurements and assessments of the ADIMEW test using elastic-plastic, cracked body, finite element analysis. (orig.)

  7. Insulated pipe clamp design

    International Nuclear Information System (INIS)

    Thin wall large diameter piping for breeder reactor plants can be subjected to significant thermal shocks during reactor scrams and other upset events. On the Fast Flux Test Facility, the addition of thick clamps directly on the piping was undesired because the differential metal temperatures between the pipe wall and the clamp could have significantly reduced the pipe thermal fatigue life cycle capabilities. Accordingly, an insulated pipe clamp design concept was developed. The design considerations and methods along with the development tests are presented. Special considerations to guard against adverse cracking of the insulation material, to maintain the clamp-pipe stiffness desired during a seismic event, to minimize clamp restraint on the pipe during normal pipe heatup, and to resist clamp rotation or spinning on the pipe are emphasized

  8. Piping Stress Analysis

    International Nuclear Information System (INIS)

    Piping stress analysis on Primary Sampling System, Reactor Cooling System, and Feedwater System for AP600 have been performed. Piping stress analysis is one of the requirements in the design of piping system. Piping stress is occurred due to static and dynamic loads during service. Analysis was carried out. Using PS+CAEPIPE software based on the individual and combination loads with assumption that failure could be happened during normal, upset, emergency and faulted condition as describe in ASME III/ANSI B31.1. With performing the piping stress analysis, the layout (proper pipe routing) of the piping system can be design with the requirements of piping stress and pipe supports in mind I.e sufficient flexibility for thermal expansion, etc to commensurate with the i tended service such as temperatures, pressure, seismic and anticipated loading

  9. Flexible ocean upwelling pipe

    Science.gov (United States)

    Person, Abraham

    1980-01-01

    In an ocean thermal energy conversion facility, a cold water riser pipe is releasably supported at its upper end by the hull of the floating facility. The pipe is substantially vertical and has its lower end far below the hull above the ocean floor. The pipe is defined essentially entirely of a material which has a modulus of elasticity substantially less than that of steel, e.g., high density polyethylene, so that the pipe is flexible and compliant to rather than resistant to applied bending moments. The position of the lower end of the pipe relative to the hull is stabilized by a weight suspended below the lower end of the pipe on a flexible line. The pipe, apart from the weight, is positively buoyant. If support of the upper end of the pipe is released, the pipe sinks to the ocean floor, but is not damaged as the length of the line between the pipe and the weight is sufficient to allow the buoyant pipe to come to a stop within the line length after the weight contacts the ocean floor, and thereafter to float submerged above the ocean floor while moored to the ocean floor by the weight. The upper end of the pipe, while supported by the hull, communicates to a sump in the hull in which the water level is maintained below the ambient water level. The sump volume is sufficient to keep the pipe full during heaving of the hull, thereby preventing collapse of the pipe.

  10. Continuous cooling transformation behavior for heat treatment of spheroidal graphite cast iron. Kyujo kokuen chutetsu no netsushoriji ni okeru renzoku reikyaku hentai kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Nakata, T.; Matsumoto, H. (Shibaura Institute of Technology, Tokyo (Japan)); Kasugai, T. (National Research Institute for Metals, Tsukuba (Japan)); Koyama, M. (Automobile Foundry Co. Ltd., Yokohama (Japan))

    1992-08-25

    In order to study basic heat treatment properties of spheroidal graphite cast iron, the continuous cooling transformation(CCT) diagrams for the material equivallent to FCD700 under various austenitized conditions were obtained. There were 4 kinds of austenitized conditions varying from 1123K and 420s to 1323K and 1,800s. Eight kinds of cooling time from the austenitized temperature to 773K ranged from 6s to 4,000s. The transformation temperature was measured by a thermal expansion method. When the austenitized temperature was increased from 1123K to 1323K, ferrite and pearlite transformation regions moved a little in the CCT diagrams and the martensite transformation temperature decreased from 493K to 458K. The bainite region in the CCT diagrams disappeared at the austenite temperatures above 1223K. The nucleation sites of ferrite and pearlite in the spheroidal graphite cast iron were generated at grain boundary between austenite and graphite but not at grain boundary between austenites. The reason of such phenomena was also studied. 10 refs., 8 figs., 2 tabs.

  11. Accelerated aging embrittlement of cast duplex stainless steel: Activation energy for extrapolation

    International Nuclear Information System (INIS)

    Cast duplex stainless steels, used extensively in LWR systems for primary pressure boundary components such as primary coolant pipes, valves, and pumps, are susceptible to thermal aging embrittlement at reactor operating or higher temperatures. Since a realistic aging embrittlement for end-of-life or life-extension conditions (i.e., 32--50 yr of aging at 280--320 degree C) cannot be produced, it is customary to simulate the metallurgical structure by accelerated aging at ∼400 degree C. Over the past several years, extensive data on accelerated aging have been reported from a number of laboratories. The most important information from these studies is the activation energy, namely, the temperature dependence of the aging kinetics between 280 and 400 degree C, which is used to extrapolate the aging characteristics to reactor operating conditions. The activation energies (in the range of 18--50 kcal/mole) are, in general, sensitive to material grade, chemical composition, and fabrication process, and a few empirical correlations, obtained as a function of bulk chemical composition, have been reported. In this paper, a mechanistic understanding of the activation energy is described on the basis of the results of microstructural characterization of various heats of CF-3, -8, and -8M grades that were used in aging studies at different laboratories. The primary mechanism of aging embrittlement at temperatures between 280 and 400 degree C is the spinodal decomposition of the ferrite phase, and M23C6 carbide precipitation on the ferrite/austenite boundaries is the secondary mechanism for high-carbon CF-8 grade. 20 refs., 10 figs., 3 tabs

  12. Heat treatment of long term serviced Cr – Mo cast steel

    Directory of Open Access Journals (Sweden)

    G. Golanski

    2010-01-01

    Full Text Available The paper presents results of research on the influence of heat treatment on the structure and properties of L20HM cast steel after long term operation at elevated temperature. Investigated cast steel was taken out from an outer frame of a steam turbine serviced for 167 424 hours at the temp. of 535 oC and pressure 12.75 MPa. In post-operating condition the investigated cast steel was characterized by mechanical properties below the required minimum and by high brittleness. Performed research on the influence of austenitizing parameters has revealed that the range of austenitizing temperatures for the examined cast steel: Ac3 + 30 ÷ 60 oC ensures obtaining of a fine austenite grain, homogeneous in size. It has been proved that tempering of bainititc – ferritic structure above 680 ÷ 690 oC causes an increase of impact energy along with a decrease of mechanical properties below the required minimum. Moreover, it has been noticed that applying of under-annealing instead of tempering, after full-annealing, guarantees the required impact energy of KV > 27J, with the mechanical properties similar to those after service.

  13. Investigation of jatropha seed oil as austempering quenchant for ductile cast iron

    Directory of Open Access Journals (Sweden)

    Akor Terngu

    2014-06-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Austempering is a multi-step process that includes austenitizing, followed by cooling rapidly enough to avoid the formation of pearlite to a temperature above the martensite start (Ms and then holding until the desired microstructure is formed. It is an isothermal heat treatment process that, when applied to cast iron, produces components that, in many cases, have properties superior to those process by conventional heat treatment. Salt bath has been recognized as the conventional quenching medium for austempering. This study investigates the suitability of jatropha seed oil as quenching medium for asaustempering ductile cast iron. Test samples were austenitized at 9500C; socked for 1hr; austempered for varying periods of 1, 2, 3, 4 and 5hrs. The result showed significant increase in tensile strength and impact energy apart from achieving an appreciable increase in hardness. It also tally with recommended values of ductile cast iron austempered in salt bath, implying that jatropha oil can be used as hot bath for the austempering of ductile cast iron. Keywords: Ausferrite, Austempering, Austenitized, Matrix So, Cked.

  14. The Impact Of the Welded Joints Made Of X8CrNiTi18–10 Stainless Steel on the Reliability Estimation of Pipes

    OpenAIRE

    Raimondas Skindaras; Jonas Bendikas; Vigantas Kumšlytis

    2011-01-01

    The chrome-nickel stainless steels of austenitic class applied in chemistry and energy industry are often used in the production of exceptional structures employed in an environment aggressive and dangerous for human life. Therefore, it is particularly significant for durability and reliability requirements. The article explores cracks that appeared in a tube made of X8CrNiTi18–10 austenitic steel. The examined pipe has worked for 90 000 hours under high temperature and pressure in an aggress...

  15. Heat Treatment Procedure Qualification for Steel Castings

    Energy Technology Data Exchange (ETDEWEB)

    Mariol Charles; Nicholas Deskevich; Vipin Varkey; Robert Voigt; Angela Wollenburg

    2004-04-29

    Heat treatment practices used by steel foundries have been carefully studied as part of comprehensive heat treatment procedure qualification development trials. These studies highlight the relationships between critical heat treatment process control parameters and heat treatment success. Foundry heat treatment trials to develop heat treatment procedure qualifications have shed light on the relationship between heat treatment theory and current practices. Furnace load time-temperature profiles in steel foundries exhibit significant differences depending on heat treatment equipment, furnace loading practice, and furnace maintenance. Time-temperature profiles of furnace control thermocouples can be very different from the time-temperature profiles observed at the center of casting loads in the furnace. Typical austenitization temperatures and holding times used by steel foundries far exceed what is required for transformation to austenite. Quenching and hardenability concepts were also investigated. Heat treatment procedure qualification (HTPQ) schema to demonstrate heat treatment success and to pre-qualify other alloys and section sizes requiring lesser hardenability have been developed. Tempering success is dependent on both tempering time and temperature. As such, furnace temperature uniformity and control of furnace loading during tempering is critical to obtain the desired mechanical properties. The ramp-up time in the furnace prior to the establishment of steady state heat treatment conditions contributes to the extent of heat treatment performed. This influence of ramp-up to temperature during tempering has been quantified.

  16. Microstructure and mechanical properties of a new type of austempered boron alloyed high silicon cast steel

    Directory of Open Access Journals (Sweden)

    Chen Xiang

    2013-05-01

    Full Text Available In the present paper, a new type of austempered boron alloyed high silicon cast steel has been developed, and its microstructures and mechanical properties at different temperatures were investigated. The experimental results indicate that the boron alloyed high silicon cast steel comprises a dendritic matrix and interdendritic eutectic borides in as-cast condition. The dendritic matrix is made up of pearlite, ferrite, and the interdendritic eutectic boride is with a chemical formula of M2B (M represents Fe, Cr, Mn or Mo which is much like that of carbide in high chromium white cast iron. Pure ausferrite structure that consists of bainitic ferrite and retained austenite can be obtained in the matrix by austempering treatment to the cast steel. No carbides precipitate in the ausferrite structure and the morphology of borides remains almost unchanged after austempering treatments. Secondary boride particles precipitate during the course of austenitizing. The hardness and tensile strength of the austempered cast steel decrease with the increase of the austempering temperature, from 250 篊 to 400 篊. The impact toughness is 4-11 J昪m-2 at room temperature and the impact fracture fractogragh indicates that the fracture is caused by the brittle fracture of the borides.

  17. Glovebox Advanced Casting System Casting Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Fielding, Randall Sidney [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-03-01

    Casting optimization in the GACS included three broad areas; casting of U-10Zr pins, incorporation of an integral FCCI barrier, and development of a permanent crucible coating. U-10Zr casting was improved over last year’s results by modifying the crucible design to minimize contact with the colder mold. Through these modifications casting of a three pin batch was successful. Incorporation of an integral FCCI barrier also was optimized through furnace chamber pressure changes during the casting cycle to reduce gas pressures in the mold cavities which led to three full length pins being cast which incorporated FCCI barriers of three different thicknesses. Permanent crucible coatings were tested against a base case; 1500°C for 10 minutes in a U-20Pu-10Zr molten alloy. None of the candidate coating materials showed evidence of failure upon initial visual examination. In all areas of work a large amount of characterization will be needed to fully determine the effects of the optimization activities. The characterization activities and future work will occur next year.

  18. Probabilistic procedure to evaluate integrity of degraded pipes under internal pressure and bending moment

    International Nuclear Information System (INIS)

    The determination of critical crack sizes or permissible/allowable loading levels in pipes with degraded pipe sections (circumferential cracks) for the assurance of component integrity is usually based on deterministic approaches. Therefore along with numerical calculational methods (finite element (FE) analyses) limit load calculations, such as e.g. the 'Plastic limit load concept' and the 'Flow stress concept' as well as fracture mechanics approximation methods as e.g. the R-curve method or the 'Ductile fracture handbook' and the R6-Method are currently used for practical application. Numerous experimental tests on both ferritic and austenitic pipes with different pipe dimensions were investigated at MPA Stuttgart. The geometries of the pipes were comparable to actual piping systems in Nuclear Power Plants, both BWR as well as PWR. Through wall cracks and part wall through cracks on the inside surface of the pipes were considered. The results of these tests were used to determine the flow stresses used within the limit load calculations. Therefore the deterministic concepts assessing the integrity of degraded pipes are available A new post-calculation of the above mentioned tests was performed using probabilistic approaches to assure the component integrity of degraded piping systems. As a result the calculated probability of failure was compared to experimental behaviour during the pipe test. Different reliability techniques were used for the verification of the probabilistic approaches. (author)

  19. Evaluation of the corrosion resistance of plasma nitrided austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Mareci, Daniel; Bolat, Georgiana [Technical Univ. Iasi (Romania). Faculty of Chemical Engineering and Environmental Protection; Strugaru, Sorin Iacob; Munteanu, Corneliu [Technical Univ. Iasi (Romania). Faculty of Mechanical Engineering; Souto, Ricardo M. [Univ. of La Laguna, Tenerife (Spain). Dept. of Chemistry

    2015-03-15

    Plasma nitriding at 500 C for 14 h was applied to austenitic 304 stainless steel for surface hardening. The effect of surface treatment on the corrosion resistance of the material was investigated in naturally-aerated 0.5 M NaCl solution for 30 days using linear potentiodynamic polarization and electrochemical impedance spectroscopy methods. Both as-cast and plasma nitrided stainless steel samples underwent spontaneous passivation, though the nitrided sample exhibited more positive zero current potential, higher breakdown potential, and lower anodic current densities than the as-cast material. Impedance spectra were interpreted in terms of a duplex passive film, corrosion resistance mainly arising from a thin inner compact layer, whereas the outer layer was more porous and less sealing. Capacitive behaviour and high corrosion resistance were observed in the low and medium frequency ranges for the nitrided samples.

  20. Evaluation of the corrosion resistance of plasma nitrided austenitic stainless steel

    International Nuclear Information System (INIS)

    Plasma nitriding at 500 C for 14 h was applied to austenitic 304 stainless steel for surface hardening. The effect of surface treatment on the corrosion resistance of the material was investigated in naturally-aerated 0.5 M NaCl solution for 30 days using linear potentiodynamic polarization and electrochemical impedance spectroscopy methods. Both as-cast and plasma nitrided stainless steel samples underwent spontaneous passivation, though the nitrided sample exhibited more positive zero current potential, higher breakdown potential, and lower anodic current densities than the as-cast material. Impedance spectra were interpreted in terms of a duplex passive film, corrosion resistance mainly arising from a thin inner compact layer, whereas the outer layer was more porous and less sealing. Capacitive behaviour and high corrosion resistance were observed in the low and medium frequency ranges for the nitrided samples.

  1. Determination of the collapse load of circumferentially cracked pipes

    International Nuclear Information System (INIS)

    Pipes related to the Primary System of PWR reactors are manufactured from high toughness austenitic and ferritic steels, which are resistant to the unstable growth of defects. A flaw in a piping system has to cause a leakage in a considerable rate, before any growth of the flaw causes a catastrophic rupture of the piping. This is the concept of LBB (Leak-Before-Break). If a conservative analysis can demonstrate that this leakage can be detected and repaired before a sudden rupture of the pipe occurs, the regulatory commission can exclude from the design basis, the postulation of a DEGB (Double-Ended Guillotine Break) hypothetic and the considerations to its associated dynamic effects. As a consequence, the protections against dynamic effects can be desconsidered, bringing an immediate economic benefice. In terms of security, the removal of the protections, give also more benefits considering the existence of more space available at the installation for inspection activities. A fundamental stage in the LBB methodology consists in the analysis of the stability of a postulated throughwall flaw in a specific piping system. In this work, the methods DPFAD (Deformation Plasticity Failure Assessment Diagram), J-T Analysis and DFM (Ductile Fracture Method) are described and applied on the determination of the instability load in some piping configurations submitted to bending containing circumferential throughwall flaws, and where geometry and material variations are considered. The instability loads obtained by these methods are compared among them and compared with some experimental results. (author)

  2. Aspects and mechanisms of austenitic stainless steel corrosion in case of sodium leaks under mineral wool insulation

    International Nuclear Information System (INIS)

    Sodium pipe rupture tests representative of Fast Reactors accidents have been carried out on austenitic stainless steel surfaces. These tests improve the authors knowledge of small sodium leakage propagation in mineral wool insulation. Furthermore, they explain the new and unexpected aspects of the crevice corrosion phenomenon which has been observed on austenitic stainless steel external pipe surfaces. Experimental results show that the corrosion is limited to a peripheral annular zone, which extends out in concentric waves. The diameter of this corrosion zone is practically constant. Furthermore, the tests show that sodium does not expand directly on the pipe surface. The sodium sprays through the mineral wool insulation, where chemical reactions between silica fibers, occluded oxygen and water vapor occur at the same time. Simultaneously, there is a diffusion phenomenon of liquid sodium droplets on the mineral wool fibers. The study allows to prove the electrochemical nature of the corrosion. The excess liquid sodium, spraying as droplets on the pipe surface, induces an anodic dissolution mechanism by differential aeration. This phenomenon explains the random microscopic and macroscopic aspects of material removal

  3. PC-PRAISE, BWR Piping Reliability Analysis

    International Nuclear Information System (INIS)

    1 - Description of program or function: PC-PRAISE is a probabilistic fracture mechanics computer code developed for IBM or IBM compatible personal computers to estimate probabilities of leak and break in nuclear power plant cooling piping. 2 - Method of solution: PC-PRAISE considers the initiation and/or growth of crack-like defects in piping weldments. The initiation analyses are based on the results of laboratory studies and field observations in austenitic piping material operating under boiling water reactor conditions. The considerable scatter in such results is quantified and incorporated into a probabilistic model. The crack growth analysis is based on (deterministic) fracture mechanics principles, in which some of the inputs (such as initial crack size) are considered to be random variables. Monte Carlo simulation, with stratified sampling on initial crack size, is used to generate weldment reliability results. 3 - Restrictions on the complexity of the problem: There is essentially no limitation with PC-PRAISE but for large number of replications used in the Monte Carlo simulation scheme, computation time may become prohibitive

  4. Predictions of failure for some of the international pipe tests using the R6 method

    International Nuclear Information System (INIS)

    The use of state-of-the-art analysis methods to predict the behavior of large scale fracture experiments has identified some significant discrepancies. The same methods are used for assessing the integrity of structures and may be giving rise to similar discrepancies which need to be examined. This paper focuses on the application to piping of the assessment method developed in the United Kingdom known as R6. The examples chosen correspond to some specific piping experiments covering cases where failure is governed by both toughness as well as plastic instability. Most of the tests chosen were conducted in the Degraded Piping Program Phase 2 of the US Nuclear Regulatory Commission, in which about 70 tests were performed. Pipes with surface cracks as well as pipes with circumferential cracks were tested under three types of loading conditions; bending moment alone, pressure alone and combined bending and pressure. Two types of material were used in the program, carbon steel and austenitic steel, some of which contained welds. Results have also been obtained on liquid metal fast breeder reactor piping in a collaborative program between Interatom (FRG) and EDF and Novatome, a Division of Framatome. The data concerned initiation and instability behavior of circumferentially through-cracked pipes. These tests were made on large austenitic pipes with material properties quite different from those of the usual light water reactor piping. Cracks were located either in the base material, in the weld metal or in the heat-affected-zone. The pipes were subjected to bending only. In this paper the results of the R6 assessments are compared with the experimental data in terms of initiation and maximum load. A statistical treatment has been used to assess the significance of the discrepancy between the theoretical and experimental results

  5. New casting coatings

    International Nuclear Information System (INIS)

    In this project the results of the researches about the influence of the four types of ceramic coatings of the evaporating patterns (on the basis of talc, mullite, zircon and cordierite) on the talc of the Lost Foam process and the castings quality are presented. For the valid evaluation of the results, some parallel examinations of the quality of castings obtained by casting in sand were carried out. (Original)

  6. Casting in Sport

    OpenAIRE

    DeCarlo, Mark; Malone, Kathy; Darmelio, John; Rettig, Arthur

    1994-01-01

    Attempts by sports medicine professionals to return high school athletes with hand and wrist injuries to competition quickly and safely have been the source of confusion and debate on many playing fields around the country. In addition to the differing views regarding the appropriateness of playing cast usage in high school football, a debate exists among sports medicine professionals as to which material is best suited for playing cast construction. Materials used in playing cast constructio...

  7. Online machine vision method for measuring the diameter and straightness of seamless steel pipes

    Science.gov (United States)

    Sun, Changku; You, Qiang; Qiu, Yu; Ye, Shenghua

    2001-11-01

    We present a novel method to measure the diameter and straightness of seamless steel pipes. A pair of line-structured lasers, which locate on different sides of the pipe but are in a common plane, cast on the pipe to create two elliptical arcs. Two CCD cameras capture these two arcs. Major and minor axis radii and spatial 3D coordinates of every corresponding elliptical cross-section center can be calculated through ellipse fitting. A pair of line-structured laser sensors, each of which includes a line-structured laser and a CCD camera, are placed at every sampling cross section of the pipe, and thus the pipe's cross-section diameter and furthermore the straightness of the pipe can be solved. We provide an on-line machine vision method for measuring a seamless steel pipe's diameter and straightness, including the design of the system, the deduction of the mathematical model, and the research of the experimental results.

  8. Control rod drive housing made of recrystallised centrifugal casting

    International Nuclear Information System (INIS)

    The possibility of fabricating the Control Rod Drive (CRD) Housings for Boiling Water Reactor (BWR) pressure vessels by recrystallised centrifugal casting without welding was investigated. The material used was to the specification ASME SA-351 CF3M, and after centrifugal casting it was cold formed by a process involving 15% to 30% plastic deformation before the final solution heat treatment, so that recrystallisation can be obtained. Various mechanical, metallurgical and nondestructive tests were performed, and the following superior characteristics were confirmed. Metallurgical tests showed that small austenite grain and 11 to 12% isolated ferrite are uniformly distributed throughout the whole parts of the CRD housing. Tests at room temperature, and up to 3000C on tensile specimens taken from various portions of the CRD housing were satisfactory. The weldability of the recrystallised casting CRD housing to Inconel stub tube was satisfactory. The attenuation of ultrasonic waves of the recrystallised casting was compared with those of cast and wrought material, and it was confirmed that ultrasonic tests can be performed with almost the same sensitivity as on wrought materials. When such nondestructive ultrasonic tests were made on the whole length of a typical sample, supported by liquid penetrant tests, no defective indications were found. (U.K.)

  9. Thermal stresses in pipes

    OpenAIRE

    Al-Zaharnah, Iyad

    2002-01-01

    This study presents results about thermal stresses in externally heated pipes that are subjected to different flow types: laminar flow, turbulent flow, and pulsating flow. The effect o f flow Reynolds number on thermal stresses in the pipe is studied. To investigate the influence o f fluid and solid properties on the resulting thermal stresses in pipes, two solids namely; steel and cooper and three fluids namely; water, coolanol-25, and mercury are used in the study. Pipes with different diam...

  10. Gradient method of cast iron latent heat identification

    Directory of Open Access Journals (Sweden)

    E. Majchrzak

    2007-12-01

    Full Text Available In the paper the cast iron latent heat in the form of three components corresponding to solidification of austenite and eutectic phases is identified. The basic information concerning the form of adequate functions approximation has been taken on the basis of cooling curve and temperature derivative courses found by means of the TDA technique. On the stage of inverse problem solution the gradient method has been used. The numerical computations have been done using the finite difference method. In the final part of the paper the example of latent heat identification is shown.

  11. Development of a duplex cast stainless steel for nuclear purposes

    International Nuclear Information System (INIS)

    The starting material was a Finnish austenitic-ferritic stainless steel belonging to the family of widely used CF 308 M cast steels. This original HKS steel failed in the Strauss tests, which are of primary importance for materials used in nuclear power piles. Development work on lowering the ferrite and interstitial impurity contents influenced the properties of the steel so much that it no longer failed the Strauss test nor showed any brittleness when tested after irradiation treatment. Welded samples also showed no brittleness, provided the welding was carried out using correct filler materials and suitable heat input. (author)

  12. Kinetic study of austenite formation during continuous heating of unalloyed ductile iron

    Science.gov (United States)

    Vázquez-Gómez, Octavio; Barrera-Godínez, José Antonio; Vergara-Hernández, Héctor Javier

    2015-01-01

    The austenite formation kinetics in unalloyed cast ductile iron was studied on the basis of dilatometry measurements, and Avrami's equation was used to estimate the material's kinetic parameters. A continuous heating transformation diagram was constructed using heating rates in the range of 0.06 to 0.83°C·s-1. As the heating rate was augmented, the critical temperatures, A c1 and A α, as well as the intercritical range, which was evaluated as the difference between the critical temperatures, Δ T = A α - A c1, increased. At a low heating rate, the kinetics of austenite formation was slow as a consequence of the iron's silicon content. The effect of heating rate on k and n, the kinetic parameters of Avrami's equation, was also determined. Parameter n, which is associated with nucleation sites and growth geometry, decreased with an increase in heating rate. In addition, parameter k increased with the increase of heating rate, suggesting that the nucleation and growth rates are carbon- and silicon-diffusion controlled during austenite formation under continuous heating.

  13. Short cracks in piping and piping welds

    International Nuclear Information System (INIS)

    This program started on March 23, 1990, and has a duration of 4 years. The objective of the program is to develop and verify analyses by using existing and new experimental data for circumferentially cracked pipes, so modifications and improvements can be made to LBB and in-service flaw evaluation criteria. There are 7 technical tasks dealing, in general, with circumferentially cracked straight pipe under quasi-static loading. The tasks are as follows: short through wall cracked (TWC) pipe evaluations, short surface-cracked pipe evaluations, bi-metallic cracked pipe evaluations, dynamic strain aging and crack jump evaluations, anisotropic fracture evaluations, crack-opening-area evaluations, and NRCPIPE code improvements. There is also a separate task to develop international cooperation, interact with Section 11 of the ASME code, and perform program management functions

  14. Pipe-to-pipe impact program

    International Nuclear Information System (INIS)

    This report documents the tests and analyses performed as part of the Pipe-to-Pipe Impact (PTPI) Program at the Pacific Northwest Laboratory. This work was performed to assist the NRC in making licensing decisions regarding pipe-to-pipe impact events following postulated breaks in high energy fluid system piping. The report scope encompasses work conducted from the program's start through the completion of the initial hot oil tests. The test equipment, procedures, and results are described, as are analytic studies of failure potential and data correlation. Because the PTPI Program is only partially completed, the total significance of the current test results cannot yet be accurately assessed. Therefore, although trends in the data are discussed, final conclusions and recommendations will be possible only after the completion of the program, which is scheduled to end in FY 1984

  15. Irradiation response of delta ferrite in as-cast and thermally aged cast stainless steel

    Science.gov (United States)

    Li, Zhangbo; Lo, Wei-Yang; Chen, Yiren; Pakarinen, Janne; Wu, Yaqiao; Allen, Todd; Yang, Yong

    2015-11-01

    To enable the life extension of Light Water Reactors (LWRs) beyond 60 years, it is critical to gain adequate knowledge for making conclusive predictions to assure the integrity of duplex stainless steel reactor components, e.g. primary pressure boundary and reactor vessel internal. Microstructural changes in the ferrite of thermally aged, neutron irradiated only, and neutron irradiated after being thermally aged cast austenitic stainless steels (CASS) were investigated using atom probe tomography. The thermal aging was performed at 400 °C for 10,000 h and the irradiation was conducted in the Halden reactor at ˜315 °C to 0.08 dpa (5.6 × 1019 n/cm2, E > 1 MeV). Low dose neutron irradiation at a dose rate of 5 × 10-9 dpa/s was found to induce spinodal decomposition in the ferrite of as-cast microstructure, and further to enhance the spinodal decomposition in the thermally aged cast alloys. Regarding the G-phase precipitates, the neutron irradiation dramatically increases the precipitate size, and alters the composition of the precipitates with increased, Mn, Ni, Si and Mo and reduced Fe and Cr contents. The results have shown that low dose neutron irradiation can further accelerate the degradation of ferrite in a duplex stainless steel at the LWR relevant condition.

  16. Microstructural characterization of second phase regions in cast stainless steels

    International Nuclear Information System (INIS)

    Full text of publication follows: Cast austenitic stainless steels offer the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the divertor cassette for the International Tokamak Experimental Reactor (ITER). Unfortunately, one of the inherent problems associated with casting stainless steel, especially large castings, is the formation of coarse dendrites with possibly inhomogeneously distributed second phases separated by up to several hundred microns in the microstructure. These microstructural features result from temperature and composition gradients that develop during solidification and subsequent cooling. However, detailed characterization of the second phase regions in the cast microstructures can be quite challenging to techniques such as transmission electron microscopy (TEM), which is useful for phase identification. furthermore, the information about the phases that may be present in the cast microstructures, both equilibrium and nonequilibrium, is important as input as well as for confirming predictions made by computational thermodynamics and solidification modeling. In this study, the investigation of second phase regions that formed in a large cast of a 316 stainless steel (equivalent to CF3M) will be presented and compared to simulations of the phases predicted by computational thermodynamic modeling of the solidification process. The preliminary TEM investigation of the cast microstructure was performed with specimens that were prepared by jet-polishing of 3 mm diameter discs. Although this approach allowed for the identification of the sigma and chi phases, which was consistent with the simulations, it was not suitable for detailed analysis of the second phase regions since these specimens often contained only grains of the gamma austenite phase. A better approach for preparing TEM specimens consisted of strategically lifting small sections of material from second phase regions

  17. Influence of Martensite Fraction on the Stabilization of Austenite in Austenitic-Martensitic Stainless Steels

    Science.gov (United States)

    Huang, Qiuliang; De Cooman, Bruno C.; Biermann, Horst; Mola, Javad

    2016-05-01

    The influence of martensite fraction ( f α') on the stabilization of austenite was studied by quench interruption below M s temperature of an Fe-13Cr-0.31C (mass pct) stainless steel. The interval between the quench interruption temperature and the secondary martensite start temperature, denoted as θ, was used to quantify the extent of austenite stabilization. In experiments with and without a reheating step subsequent to quench interruption, the variation of θ with f α' showed a transition after transformation of almost half of the austenite. This trend was observed regardless of the solution annealing temperature which influenced the martensite start temperature. The transition in θ was ascribed to a change in the type of martensite nucleation sites from austenite grain and twin boundaries at low f α' to the faults near austenite-martensite (A-M) boundaries at high f α'. At low temperatures, the local carbon enrichment of such boundaries was responsible for the enhanced stabilization at high f α'. At high temperatures, relevant to the quenching and partitioning processing, on the other hand, the pronounced stabilization at high f α' was attributed to the uniform partitioning of the carbon stored at A-M boundaries into the austenite. Reduction in the fault density of austenite served as an auxiliary stabilization mechanism at high temperatures.

  18. Effect of molybdenum, vanadium, boron on mechanical properties of high chromium white cast iron in as-cast condition

    Science.gov (United States)

    Nurjaman, F.; Sumardi, S.; Shofi, A.; Aryati, M.; Suharno, B.

    2016-02-01

    In this experiment, the effect of the addition carbide forming elements on high chromium white cast iron, such as molybdenum, vanadium and boron on its mechanical properties and microstructure was investigated. The high chromium white cast iron was produced by casting process and formed in 50 mm size of grinding balls with several compositions. Characterization of these grinding balls was conducted by using some testing methods, such as: chemical and microstructure analysis, hardness, and impact test. From the results, the addition of molybdenum, vanadium, and boron on high chromium white cast iron provided a significant improvement on its hardness, but reduced its toughness. Molybdenum induced fully austenitic matrix and Mo2C formation among eutectic M7C3 carbide. Vanadium was dissolved in the matrix and carbide. While boron was played a role to form fine eutectic carbide. Grinding balls with 1.89 C-13.1 Cr-1.32 Mo-1.36 V-0.00051 B in as-cast condition had the highest hardness, which was caused by finer structure of eutectic carbide, needle like structure (upper bainite) matrix, and martensite on its carbide boundary.

  19. Formation of microstructures in the spheroidal graphite cast iron

    International Nuclear Information System (INIS)

    Pipeline systems for hydraulic networks are obtained via centrifugal casting of spheroidal graphite cast iron. The very high cooling rate that is achieved in the skin of the product can sometimes lead to carbide instead of graphite in cast iron. An experimental device has been built in the laboratory that allows reproducing the extreme thermal conditions encountered during formation of skin of centrifugally cast pipes. Liquid metal droplets fall on a cold substrate. Rapid directional solidification occurs. The temperature evolution of the lower surface of the droplet is recorded during the very first moment of the solidification (t < 200 ms) thanks to a photodiode, which is located below the substrate. The microstructures that are obtained in laboratory are characterised in both the as-cast state and the heat-treated state. They are compared to the centrifugally cast ones. A model of directional solidification of cast iron under a very large temperature gradient has been built. It allows explaining the transition from stable to metastable micro structure that was observed in the products and reproduced in the laboratory samples.

  20. Explosive Surface Hardening of Austenitic Stainless Steel

    Science.gov (United States)

    Kovacs-Coskun, T.

    2016-04-01

    In this study, the effects of explosion hardening on the microstructure and the hardness of austenitic stainless steel have been studied. The optimum explosion hardening technology of austenitic stainless steel was researched. In case of the explosive hardening used new idea mean indirect hardening setup. Austenitic stainless steels have high plasticity and can be easily cold formed. However, during cold processing the hardening phenomena always occurs. Upon the explosion impact, the deformation mechanism indicates a plastic deformation and this deformation induces a phase transformation (martensite). The explosion hardening enhances the mechanical properties of the material, includes the wear resistance and hardness. In case of indirect hardening as function of the setup parameters specifically the flayer plate position the hardening increased differently. It was find a relationship between the explosion hardening setup and the hardening level.

  1. Microstructure and Mechanical Properties of ADI Depending on Austenitization Methods and Parameters

    Directory of Open Access Journals (Sweden)

    T. Giętka

    2012-04-01

    Full Text Available Ductile iron was quenched using two-variant isothermal transformation. The first treatment variant consisted of one-phase austenitization at a temperature t = 830, 860 or 900 C, cooling down to an isothermal transformation temperature of 300 or 400 C and holding from 8 to 64 minutes. The second treatment variant consisted of two-phase austenitization. Cast iron was austenitizied at a tem- perature t = 950 C and cooled down to a supercritical temperature t ’ = 900, 860 or 830 C. Isothermal transformation was conducted under the same conditions as those applied to the first variant. Ferrite cast iron was quenched isothermally. Basic strength (Rp0.2, Rm and plastic (A5 properties as well as matrix microstructure and hardness were examined.As a result of heat treatment, the following ADI grades were obtained: EN-GJS-800-8, EN-GJS-1200-2 and EN-GJS-1400-1 in accordance with PN–EN 1564:2000 having plasticity of 1.5÷4 times more than minimum requirements specified in the standard.

  2. The Mossbauer spectroscopy studies of retained austenite

    Directory of Open Access Journals (Sweden)

    J. Frackowiak

    2007-10-01

    Full Text Available Purpose: of this paper: This paper completes the knowledge concerning the mechanisms of destabilization and properties of retained austenite. Investigations were performed on 120MnCrMoV8-6-4-2 steel, which was designed in 1998, in Phase Transformations Research Group of Department of Physical and Powder Metallurgy at the Faculty of Metals Engineering and Industrial Computer Science at AGH University of Science and Technology in Krakow.Design/methodology/approach: The samples of investigated steel were austenitized at the temperature of 900ºC and hardened in oil. Next, three from four samples were tempered. Tempering consisted of heating the samples up to chosen temperatures with a heating rate of 0.05ºC/s and, after reaching desired temperature, fast cooling. CEMS technique was applied for Mössbauer studies.Findings: Stabilized by heating up to 80ºC retained austenite, in the result of mechanical destabilization, transforms into low-temperature tempered martensite, with the structure of low bainite (into the structural constituent in which ε carbide exists.Research limitations/implications: The influence of the temperature, up to which the samples were heated during tempering, on the mechanical stability of retained austenite and on the products of its transformation, was determined.Practical implications: Changes occuring in retained austenite during tempering of steel of high hardenability (hardness, developed for potential applications on tools of enhanced wear resistance, were described.Originality/value: Mössbauer spectroscopy was applied not only for qantitative analysis of retained austenite, but also to analyze the values of quadrupole splitting and isomeric shift, what resulted in significant conclusions concerning the changes in its chemical composition, microstructure, and the level of stresses being present in it.

  3. A thermally coupled flow formulation with microstructural evolution for hypoeutectic cast-iron solidification

    Energy Technology Data Exchange (ETDEWEB)

    Celentano, D.; Cruchaga, M. [Univ. de Santiago de Chile (Chile)

    1999-08-01

    A thermally coupled incompressible flow formulation, including microstructural phase-change effects, is presented. The governing equations are written in the framework of the finite-element method using a generalized streamline operator technique. In particular, a hypoeutectic cast-iron microstructural model accounting for primary austenite and eutectic solidification is considered. An inverse level rule has been employed to describe the austenite formation, while the eutectic (graphite and cementite) fractions are assumed to be governed by nucleation and growth laws. The application of this methodology in the area of casting solidification constitutes an original contribution of this work. Further, an enhanced staggered scheme is also proposed in order to solve the resulting strongly coupled discretized equations. The analysis of a solidification problem, with particular interest in the influence of the natural convection on the microstructural formation, is performed. The numerical results obtained with the present formulation allow prediction of the flow patterns, volume-fraction distributions, and recalescences developed during the process.

  4. Cast iron - a predictable material

    OpenAIRE

    Jorg C. Sturm; Guido Busch

    2011-01-01

    High strength compacted graphite iron (CGI) or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications. The mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron castings. New products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast components. During the last 20 years, casting process s...

  5. Recycle of radiologically contaminated austenitic stainless steels

    International Nuclear Information System (INIS)

    The United States Department of Energy owns large quantities of radiologically contaminated austenitic stainless steel which could by recycled for reuse if appropriate release standards were in place. Unfortunately, current policy places the formulation of a release standard for USA industry years, if not decades, away. The Westinghouse Savannah River Company, Idaho National Engineering Laboratory and various university and industrial partners are participating in initiative to recycle previously contaminated austenitic stainless steels into containers for the storage and disposal of radioactive wastes. This paper describes laboratory scale experiments which demonstrated the decontamination and remelt of stainless steel which had been contaminated with radionuclides

  6. Modeling of austenite to ferrite transformation

    Indian Academy of Sciences (India)

    Mohsen Kazeminezhad

    2012-06-01

    In this research, an algorithm based on the -state Potts model is presented for modeling the austenite to ferrite transformation. In the algorithm, it is possible to exactly track boundary migration of the phase formed during transformation. In the algorithm, effects of changes in chemical free energy, strain free energy and interfacial energies of austenite–austenite, ferrite–ferrite and austenite–ferrite during transformation are considered. From the algorithm, the kinetics of transformation and mean ferrite grain size for different cooling rates are calculated. It is found that there is a good agreement between the calculated and experimental results.

  7. Nanoscopic strength analysis of work-hardened low carbon austenitic stainless steel, 316SS

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) occurs in shrouds and piping of low carbon austenitic stainless steels at nuclear power plants. A work-hardened layer, where the transgranular SCC initiates, is considered to be one of the probable cause for this occurrence. In order to clarify the microstructural characteristics of work-hardened layer at the surface of shrouds or piping, the strengthen analysis of low carbon austenitic stainless steel, 316SS, rolled at the reduction in area, RA, of 10, 20, 30, 40 and 50% at room temperature were conducted on a nanoscopic scale, using an ultra-microhardness tester, TEM and SEM. TEM and SEM observation showed that the microstructural parameters are the dislocation cell size, dcel, coarse slip spacing, lcsl, and austenitic grain size, dγ. Referring 10dcel and 10lcsl, Vickers hardness, HV, corresponding to macro strength was expressed as Hυ=Hυ*bas + Hυ*sol + Hυ*dis + Hυ*cel + Hυ*csl. Hυ*bas (=100) is the base hardness, Hυ*sol is the solid solution strengthening hardness, Hυ*dis is the dislocation strengthening hardness in the dislocation cell, and Hυ*cel and Hυ*csl are the fine grain strengthening hardness due to the dislocation cell and coarse slip. Hυ*sol was about 50, independently of RA. Hυ*dis was zero at RA 30%. Hυ*cel and Hυ*csl increased with increasing in RA and were kept constant at about 50 and 120 at RA=20 and 30%, respectively. It was suggested from these results that all dislocations introduced by rolling might be dissipated for the creation of dislocation cells and coarse slips at RA 30%. (author)

  8. Nanoscopic strength analysis of work-hardened L-grade austenitic stainless steel, 316(NG)

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) occurs in shrouds and piping of L-grade austenitic stainless steels at nuclear power plants. A work-hardened layer, where the transgranular SCC initiates, is considered to be one of the probable cause for this occurrence. In order to clarify the microstructural characteristics of work-hardened layer at the surface of shrouds or piping, the strengthen analysis of L-grade austenitic stainless steel, 316(NG), rolled at the reduction in area, RA, of 10, 20, 30, 40 and 50% at room temperature were conducted on a nanoscopic scale, using an ultra-microhardness tester, TEM and SEM. TEM and SEM observation showed that the microstructural parameters are the dislocation cell size, dcel, coarse slip spacing, lcsl, and austenitic grain size, dγ. Referring 10dcel and 10lcsl, Vickers hardness, Hυ, corresponding to macro strength was expressed as Hυ = Hυ*bas + Hυ*sol + Hυ*dis + Hυ*cel + Hυ*csl. Hυ*bas(=100) is the base hardness, Hυ*sol is the solid solution strengthening hardness, Hυ*dis is the dislocation strengthening hardness in the dislocation cell, and Hυ*cel and Hυ*csl are the fine grain strengthening hardness due to the dislocation cell and coarse slip. Hυ*sol was about 50, independently of RA. Hυ*dis was zero at RA30%. Hυ*cel and Hυ*csl increased with increasing in RA and were kept constant at about 50 and 120 at RA=20 and 30%, respectively. It was suggested from these results that all dislocations introduced by rolling might be dissipated for the creation of dislocation cells and coarse slips at RA30%. (author)

  9. Reactor process water (PW) piping inspections, 1984--1990

    International Nuclear Information System (INIS)

    In July 1983, the NRC ordered the shutdown of five boiling water reactors (BWR's) because of concerns about reliability of ultrasonic examination for detecting intergranular stress corrosion cracking (IGSCC). These concerns arose because of leaking piping at Niagara Mohawk's Nine Mile Point which was attributed to IGSCC. The leaks were detected shortly after completion of ultrasonic examinations of the piping. At that time, the Dupont plant manager at Savannah River (SR) directed that investigations be performed to determine if similar problems could exist in SR reactors. Investigation determined that all conditions believed necessary for the initiation and propagation of IGSCC in austenitic stainless steel exist in SR reactor process water (PW) systems. Sensitized, high carbon, austenitic stainless steel, a high purity water system with high levels of dissolved oxygen, and the residual stresses associated with welding during construction combine to provide the necessary conditions. A periodic UT inspection program is now in place to monitor the condition of the reactor PW piping systems. The program is patterned after NRC NUREG 0313, i.e., welds are placed in categories based on their history. Welds in upgraded or replacement piping are examined on a standard schedule (at least every five years) while welds with evidence of IGSCC, evaluated as acceptable for service, are inspected at every extended outage (15 to 18 months). This includes all welds in PW systems three inches in diameter and above. Welds are replaced when MSCC exceeds the replacement criteria of more than twenty percent of pipe circumference of fifty percent of through-wall depth. In the future, we intend to perform flow sizing with automated UT techniques in addition to manual sizing to provide more information for comparison with future examinations

  10. Improving chill control in iron powder treated slightly hypereutectic grey cast irons

    Directory of Open Access Journals (Sweden)

    Iulian Riposan

    2011-05-01

    Full Text Available Recent studies revealed that in eutectic to slightly hypereutectic grey irons (CE = 4.3%-4.5% the presence of austenite dendrites provides an opportunity to improve the cast iron properties, as a high number of eutectic cells are “reinforced” by austenite dendrites. An iron powder addition proved to be important by promoting dendritic austenite in hypereutectic irons, but was accompanied by adverse effect on the characteristics of potential nuclei for graphite. The purpose of the present paper is to investigate the solidification pattern of these irons. Chill wedges with different cooling moduli (CM = 0.11 – 0.43 cm were poured in resin bonded sand and metal moulds. Relative clear / mottled / total chill measurement criteria were applied. Iron powder additions led to a higher chill tendency, while single inoculation showed the strongest graphitizing effect. The various double treatments show an intermediate position, but the inoculant added after iron powder appears to be the most effective in reducing base iron chill tendency, for all cooling moduli and chill evaluation parameters. This performance reflects the improved properties of (Mn,XS polygonal compounds as nucleation sites for graphite, especially in resin bonded sand mould castings. Both austenite and graphite nucleation benefit from a double addition of iron powder + inoculant, with positive effect on the final structure and chill tendency.

  11. Evaluation of the mechanical properties of Niobium modified cast AISI H 13 hot work tool steel

    International Nuclear Information System (INIS)

    In this research, the effects of partially replacing of vanadium and molybdenum with niobium on the mechanical properties of AISIH 13 hot-work tool steel have been studied. Cast samples made of the modified new steel were homogenized and austenitized at different conditions, followed by tempering at the specified temperature ranges. Hardness, red hardness, three point bending test and Charpy impact test were carried out to evaluate the mechanical properties together with characterizing the microstructure of the modified steel using scanning electron microscope. The results show that niobium addition modifies the cast structure of Nb-alloyed steel, and increases its maximum hardness. It was found that bending strength; bending strain, impact strength, and red hardness of the modified cast steel are also higher than those of the cast H13 steel, and lower than those of the wrought H13 steel.

  12. HPFRCC - Extruded Pipes

    DEFF Research Database (Denmark)

    Stang, Henrik; Pedersen, Carsten

    1996-01-01

    The present paper gives an overview of the research onHigh Performance Fiber Reinforced Cementitious Composite -- HPFRCC --pipes recently carried out at Department of Structural Engineering, Technical University of Denmark. The project combines material development, processing technique development......-w$ relationship is presented. Structural development involved definition of a new type of semi-flexiblecement based pipe, i.e. a cement based pipe characterized by the fact that the soil-pipe interaction related to pipe deformation is an importantcontribution to the in-situ load carrying capacity of the pipe...... itself. The structural modeling of the pipe was done making direct use of the $\\sigma-w$ material characterization. The processing technique developed is a novel type of extrusion combiningease of material mixing and few requirements for material pre-processingwith a high degree of accuracy and stability...

  13. HPFRCC - Extruded Pipes

    DEFF Research Database (Denmark)

    Stang, Henrik; Pedersen, Carsten

    The present paper gives an overview of the research onHigh Performance Fiber Reinforced Cementitious Composite -- HPFRCC --pipes recently carried out at Department of Structural Engineering, Technical University of Denmark. The project combines material development, processing technique development......-w$ relationship is presented. Structural development involved definition of a new type of semi-flexiblecement based pipe, i.e. a cement based pipe characterized by the fact that the soil-pipe interaction related to pipe deformation is an importantcontribution to the in-situ load carrying capacity of the pipe...... itself. The structural modeling of the pipe was done making direct use of the $\\sigma-w$ material characterization. The processing technique developed is a novel type of extrusion combiningease of material mixing and few requirements for material pre-processingwith a high degree of accuracy and stability...

  14. Improving the resistance to carburising of creep-resistant castings

    Directory of Open Access Journals (Sweden)

    B. Piekarski

    2008-12-01

    Full Text Available The study presents the results of own investigations and of the investigations described in technical literature regarding various methods of improving the resistance to carburising of the creep-resistant structural parts of carburising furnaces. Most of the studies referred to were carried out in a Foundry of the Szczecin University of Technology. The results of the investigations on the effect of chemical composition of austenitic cast steel on its resistance to the carburising effect controlled through application of the anti-carburising coatings based on aluminium and constituted on high-alloy steel substrate were summarised. The possibility to use machining of castings as a means to raise their performance life in carburising atmosphere was also mentioned.

  15. Contribution to the assessment of thermal ageing of stainless steel castings and welds

    International Nuclear Information System (INIS)

    Indentation tests are considered for measuring and verifying of thermal ageing of stainless steel castings and welds in service. Therefore, relations between indentation- and tensile diagrams were analyzed. Conventional tensile characteristics, deduced from the indentation diagram, should be used for fracture toughness prediction. Form of correlation of yield stress and tensile strength on one side and of fracture toughness on the other side was proposed, which is specific for austenitic-ferritic two-phase materials. Properties of castings and welds were compared and analyzed within the framework of a mesomechanical homogenization model with micromechanical effect of geometric slip distance. (author)

  16. An Informatics Based Approach to Reduce the Grain Size of Cast Hadfield Steel

    Science.gov (United States)

    Dey, Swati; Pathak, Shankha; Sheoran, Sumit; Kela, Damodar H.; Datta, Shubhabrata

    2016-04-01

    Materials Informatics concept using computational intelligence based approaches are employed to bring out the significant alloying additions to achieve grain refinement in cast Hadfield steel. Castings of Hadfield steels used for railway crossings, requires fine grained austenitic structure. Maintaining proper grain size of this component is very crucial in order to achieve the desired properties and service life. This work studies the important variables affecting the grain size of such steels which includes the compositional and processing variables. The computational findings and prior knowledge is used to design the alloy, which is subjected to a few trials to validate the findings.

  17. Hydrogen embrittlement of cast 13% Cr 6% NiMo steel

    International Nuclear Information System (INIS)

    A study of the hydrogen embrittlement resistance of cast 13Cr6NiMo steel after various alternative tempering treatment is reported. The threshold levels of the stress intensity factor are examined as they relate to the residual austenite content in the structure of lath martensite, the type of fracture found on the specimens and the surface segregation of phosphorus observed on them. (author)

  18. Microstructure analysis of AISI 304 stainless steel produced by twin-roll thin strip casting process

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The microstructure of AISI 304 austenite stainless steel fabricated by the thin strip casting process were investigated using optical microscope, scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD).The microstructures of the casting strips show a duplex structure consisting of delta ferrite and austenite. The volume fraction of the delta ferrite is about 9.74vol% at the center and 6.77vol% at the surface of the casting thin strip, in vermicular and band shapes. On account of rapid cooling and solidification in the continuous casting process, many kinds of inclusions and precipitates have been found. Most of the inclusions and precipitates are spherical complex compounds consisting of oxides, such as, SiO2, MnO, Al2O3,Cr2O3,and FeO or their multiplicity oxides of MnO·Al2O3,2FeO·SiO2, and 2MnO·SiO2. Many defects including dislocations and stacking faults have also formed during the rapid cooling and solidification process, which is helpful to improve the mechanical properties of the casting strips.

  19. The influence of fabricating conditions and stability of austenite on forming behaviour of austenitic stainless steels

    International Nuclear Information System (INIS)

    The object of the investigation is the effect of various conditions of cold rolling austenitic stainless steels on the mechanical and technological properties and on the behaviour during forming with requirements in stretching and deep drawing. Fabricating 3 coils of various stability of austenite the degree of cold forming between the annealing processes is varied by cold rolling from the thickness of hot rolled coil to final thickness without or with one or two intermediate annealings. The most important results for cold forming sheets are: most favourable stretch forming behaviour is gained with instable austenitic steels, becomes better with increasing sheet thickness most favourable deep drawing behaviour is gained with highest degrees of cold rolling before final annealing, is undependent from the stability of austenite. Favourable is cold rolling to the highest degree before intermediate annealing, whilst the deformation before final annealing is of greater importance. According to the results conditions can be given for cold rolling to get best forming behaviour. (orig.)

  20. Effect of Destabilizing Heat Treatment on Solid-State Phase Transformation in High-Chromium Cast Irons

    Science.gov (United States)

    Efremenko, Vasily; Shimizu, Kazumichi; Chabak, Yuliia

    2013-12-01

    This work describes the influence of secondary carbide precipitation at destabilizing heat treatment on kinetics of austenite phase transformation at a subcritical range of temperatures in high-Cr cast irons, alloyed with 4 to 6 wt pct of Mn or by complex Mn-Ni-Mo (Mn-Cu-Mo). The samples were soaked at 1073 K to 1373 K (800 °C to 1100 °C) (destabilization) or at 573 K to 973 K (300 °C to 700 °C) (subcritical treatment); the combination of destabilization and subcritical treatment was also used. The investigation was carried out with application of optical and electron microscopy and bulk hardness measurement. Time-temperature-transformation (TTT) curves of secondary carbide precipitation and pearlite transformation for as-cast austenite and destabilized austenite were built in this work. It was determined that the secondary carbide precipitation significantly inhibited the pearlite transformation rate at 823 K to 973 K (550 °C to 700 °C). The inhibition effect is more evident in cast irons alloyed with complex Mn-Ni-Mo or Mn-Cu-Mo. The possible reasons for transformation decelerating could be austenite chemical composition change (enriching by Ni, Si, and Cu, and depleting by Cr) and stresses induced by secondary carbide precipitation.

  1. The ancient Chinese casting techniques

    Directory of Open Access Journals (Sweden)

    Tan Derui

    2011-02-01

    Full Text Available In the course of Chinese civilization, which lasted more than 5,000 years, casting production has made a huge contribution. In this paper, some representative metal castings were presented. According to their forming techniques, they can be grouped into stone mould casting, clay mould casting, ablation casting, lost wax casting, stack casting, permanent mould casting, sand casting, etc. According to their materials, they can be categorized into tin bronze, bimetallic bronze, malleable cast iron, ductile cast iron, brass, cupronickel alloy (Packtong, etc. According to their surface decorative techniques they can be devided into gem inlay, gilding, gold and silver inlay, copper inlay, engraved decoration, surface tin-enrichment, mother-of-pearl inlay, burnished works with gold or silver inlay, surface coloring and cloisonné enamel, etc.

  2. Magnetic State of Deformed Austenite Before and After Martensite Nucleation in Austenitic Stainless Steels

    Institute of Scientific and Technical Information of China (English)

    GennadiiVSnizhnoi; MariyaSRasshchupkyna’

    2012-01-01

    The effect of the increase in the paramagnetic susceptibility of austenite up to the true value of the deformation-induced martensite transition point es has been experimentally established in steels X6CrNiTil8-10 (correspon& ing to AISI 321 steels). At this point nucleation and accumulation of martensite with the increase in the extent of de- formation but at a constant magnetic state of austenite takes place.

  3. Effects of heat treatment on mechanical properties of modified cast AISI D3 tool steel

    International Nuclear Information System (INIS)

    Highlights: • Secondary hardening occurred when tempered at 500 °C and austenitized at 1050 °C. • Hardness of new steel is about 1 HRC higher than D3 steel, when tempered at 300 °C. • New steel has less bending strength and strain compared with D3 steel. • With increasing hardness wear resistance is improved about 56%. • Linear relationship observed between weight loss and hardness of modified steel. - Abstract: In this research new modified as-cast cold work AISI D3 tool steel was produced by increasing Ti and Nb and decreasing Cr. At first, Cast samples were homogenized at optimized cycle and then austenitized and tempered within the specified temperature ranges. Mechanical properties and wear behavior were determined by performing hardness test, three point bending test and pin on disc wear test. Also, scanning electron microscope was employed to characterize the new modified steel. For the specimens austenitized and tempered at 1050 °C and 500 °C respectively, the secondary hardening effect was observed which was consistent with lower weight loss of pin on disc wear test results. The results show that, the new modified as-cast steel represents hardness and wear resistance equal to or better than that of standard wrought D3 steel, while its strength and toughness are lower than those of wrought steel

  4. The characteristics of two-phase 22Cr-6Ni-2Mo-1,5Cu cast steel

    Directory of Open Access Journals (Sweden)

    B. Kalandyk

    2008-12-01

    Full Text Available The paper discusses the effect of the casting wall thickness on the segregation of alloying elements in two-phase (F-A 22Cr-6Ni-2Mo-1,5Cu cast steel. The values of the distribution coefficient k0 for Cr, Mo, Si, and Ni, Mn, Cu in the cast stepped test piece walls of three different thicknesses were determined. After solutioning, the values of Rm, R0,2, A5 and Z were measured in the wall of 45 mm thickness and were compared with the results obtained for austenitic cast steel of 18Cr-9Ni grade. In the examined cast steel also the content of δ ferrite and the value of PREN were determined.

  5. High-temperature materials for nuclear power plant piping

    International Nuclear Information System (INIS)

    The authors discuss the properties and problems of austenitic high-temperature steels or Ni alloys used as materials for pipelines with high operating temperatures in nuclear power plants, e.g. sodium-cooled fast breeders (5500C) and high-temperature reactors (7500C or 9500C). Sturcture and properties (mechanical and technical) of materials are described, e.g. cyclic strength, fatigue life, fracture mechanics, corrosion. Unresolved problems, e.g. multiaxial leads on pipe geometries and accumulation of defects at very high temperatures, are discussed. (orig.)

  6. Aging degradation of cast stainless steel

    International Nuclear Information System (INIS)

    A program is being conducted to investigate the significance of in-service embrittlement of cast duplex stainless steels under light-water reactor operating conditions. Microstructures of cast materials subjected to long-term aging either in reactor service or in the laboratory have been characterized by TEM, SANS, and APFIM techniques. Two precipitate phases, i.e., the Cr-rich α' phase and the Ni- and Si-rich G phase, have been identified in the ferrite matrix of the aged steels. The results indicate that the low-temperature embrittlement is primarily caused by α' precipitates which form by spinodal decomposition. The relative contribution of the G phase to loss of toughness is now known. Microstructural data also indicate that weakening of the ferrite/austenite phase boundary by carbide precipitates has a significant effect on the onset and extent of embrittlement of the high-carbon CF-8 and CF-8M grades of stainless steels, particularly after aging at 400 or 4500C. Data from Charpy-impact, tensile, and J-R curve tests for several heats of cast stainless steel aged up to 10,000 h at 350, 400, and 4500C are presented and correlated with the microstructural results. Thermal aging of the steels results in an increase in tensile strength and a decrease in impact energy, J/sub IC/, and tearing modulus. The fracture toughness results show good agreement with the Charpy-impact data. The effects of compositional and metallurgical variables on loss of toughness are discussed

  7. Corrosion of plasma nitrided austenitic stainless steels

    International Nuclear Information System (INIS)

    The corrosion behaviour of plasma nitrided austenitic stainless steel grades AISI 304, 316 and 321 was studied at various temperatures. Certain plasma nitriding cycles included a post-oxidation treatment. The corrosion rates were measured using linear polarisation technique. Results showed that corrosion rate increased with the plasma nitriding temperature. Minimum deterioration occurred at 653K. (author). 2 tabs., 4 figs., 10 refs

  8. Bainite orientation in plastically deformed austenite

    OpenAIRE

    Klobčar, Damjan; Shirzadi, A. A.; Abreu, H.; Pocock, L.; Withers, P.J.; Bhadeshia, Harshad Kumar Dharamshi Hansraj

    2015-01-01

    Experiments have been conducted to see whether specific crystallographic variants of bainite form in polycrystalline steel when transformation occurs from plastically deformed austenite which is otherwise free from externally applied stress. It is demonstrated by studying both overall and microtexture that there is no perceptible variant selection as bainite forms. Indeed, the texture is found to weaken on transformation.

  9. Clean Metal Casting

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The objective of this project is to develop a technology for clean metal processing that is capable of consistently providing a metal cleanliness level that is fit for a given application. The program has five tasks: Development of melt cleanliness assessment technology, development of melt contamination avoidance technology, development of high temperature phase separation technology, establishment of a correlation between the level of melt cleanliness and as cast mechanical properties, and transfer of technology to the industrial sector. Within the context of the first task, WPI has developed a standardized Reduced Pressure Test that has been endorsed by AFS as a recommended practice. In addition, within the context of task1, WPI has developed a melt cleanliness sensor based on the principles of electromagnetic separation. An industrial partner is commercializing the sensor. Within the context of the second task, WPI has developed environmentally friendly fluxes that do not contain fluorine. Within the context of the third task, WPI modeled the process of rotary degassing and verified the model predictions with experimental data. This model may be used to optimize the performance of industrial rotary degassers. Within the context of the fourth task, WPI has correlated the level of melt cleanliness at various foundries, including a sand casting foundry, a permanent mold casting foundry, and a die casting foundry, to the casting process and the resultant mechanical properties. This is useful in tailoring the melt cleansing operations at foundries to the particular casting process and the desired properties of cast components.

  10. Casting in sport.

    Science.gov (United States)

    Decarlo, M; Malone, K; Darmelio, J; Rettig, A

    1994-03-01

    Attempts by sports medicine professionals to return high school athletes with hand and wrist injuries to competition quickly and safely have been the source of confusion and debate on many playing fields around the country. In addition to the differing views regarding the appropriateness of playing cast usage in high school football, a debate exists among sports medicine professionals as to which material is best suited for playing cast construction. Materials used in playing cast construction should be hard enough to provide sufficient stabilization to the injured area and include adequate padding to absorb blunt impact forces. The purpose of the biomechanical portion of this investigation was to attempt to determine the most appropriate materials for use in constructing playing casts for the hand and wrist by assessing different materials for: 1) hardness using a Shore durometer, and 2) ability to absorb impact using a force platform. Results revealed that RTV11 and Scotchcast were the "least hard" of the underlying casting materials and that Temper Stick foam greatly increased the ability of RTV11 to absorb impact. Assessment of the mechanical properties of playing cast materials and review of current developments in high school football rules are used to aid practitioners in choosing the most appropriate materials for playing cast construction. PMID:16558257

  11. The Effects of Cold Work on the Microstructure and Mechanical Properties of Intermetallic Strengthened Alumina-Forming Austenitic Stainless Steels

    Science.gov (United States)

    Hu, B.; Trotter, G.; Baker, Ian; Miller, M. K.; Yao, L.; Chen, S.; Cai, Z.

    2015-08-01

    In order to achieve energy conversion efficiencies of >50 pct for steam turbines/boilers in power generation systems, materials are required that are both strong and corrosion-resistant at >973 K (700 °C), and economically viable. Austenitic steels strengthened with Laves phase, NiAl and Ni3Al precipitates, and alloyed with aluminum to improve oxidation resistance, are potential candidate materials for these applications. The microstructure and microchemistry of recently developed alumina-forming austenitic stainless steels have been characterized by scanning electron microscopy, transmission electron microscopy, and synchrotron X-ray diffraction. Different thermo-mechanical treatments were performed on these steels to improve their mechanical performance. These reduced the grain size significantly to the nanoscale (~100 nm) and the room temperature yield strength to above 1000 MPa. A solutionizing anneal at 1473 K (1200 °C) was found to be effective for uniformly redistributing the Laves phase precipitates that form upon casting.

  12. Symptomatic stent cast.

    LENUS (Irish Health Repository)

    Keohane, John

    2012-02-03

    Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.

  13. Uniaxial Fatigue of HDPE-100 Pipe. Experimental Analysis

    Directory of Open Access Journals (Sweden)

    A. Aid

    2014-04-01

    Full Text Available In this paper, an experimental analysis for determining the fatigue strength of PE-100, one of the most used High Density Polyethylene (HDPE materials for pipes, under cyclic axial loadings is presented. HDPE is a thermoplastic material used for piping systems, such as natural gas distribution systems, sewer systems and cold water systems, which provides a good alternative to metals such as cast iron or carbon steel. One of the causes for failures of HDPE pipes is fatigue which is the result of pipes being subjected to cyclic loading, such as internal pressure, weight loads or external loadings on buried pipes, which generate stress in different directions: circumferential, longitudinal and radial. HDPE pipes are fabricated using an extrusion process, which generates anisotropic properties. By testing in the Laboratory a series of identical specimens obtained directly from PE-100 HDPE pipes in longitudinal directions, the relationships between amplitude stress and number of cycles (S-N curve test frequency 2 Hz and stress ratio R = 0.0 are established.

  14. Expanded austenite in nitrided layers deposited on austenitic and super austenitic stainless steel grades; Analise da austenita expandida em camadas nitretadas em acos inoxidaveis austeniticos e superaustenitico

    Energy Technology Data Exchange (ETDEWEB)

    Casteletti, L.C.; Fernandes, F.A.P.; Heck, S.C. [Universidade de Sao Paulo (EESC/USP), Sao Carlos, SP (Brazil). Escola de Engenharia. Dept. de Engenharia de Materais, Aeronautica e Automobilistica; Oliveira, A.M. [Instituto de Educacao, Ciencia e Tecnologia do Maranhao (IFMA), Sao Luis, MA (Brazil); Gallego, J., E-mail: gallego@dem.feis.unesp.b [UNESP, Ilha Solteira, SP (Brazil). Dept. Engenharia Mecanica

    2010-07-01

    In this work nitrided layers deposited on austenitic and super austenitic stainless steels were analyzed through optical microscopy and X-rays diffraction analysis (XRD). It was observed that the formation of N supersaturated phase, called expanded austenite, has promoted significant increment of hardness (> 1000HV). XRD results have indicated the anomalous displacement of the diffracted peaks, in comparison with the normal austenite. This behavior, combined with peaks broadening, it was analyzed in different nitriding temperatures which results showed good agreement with the literature. (author)

  15. Aspects and mechanisms of austenitic stainless steel corrosion in case of sodium leaks under mineral wool insulation

    International Nuclear Information System (INIS)

    Sodium pipe rupture tests representative of Fast Reactors Accidents have been carried out on austenitic stainless steel surfaces. These tests improve our knowledge of small sodium leakage propagation in mineral wool insulation. They explain the new and unexpected aspects of the crevice corrosion phenomenon which has been observed on austenitic stainless steel pipe surfaces. Experimental results show that corrosion is limited to a peripheral annular zone, which extends out in concentric waves. The diameter of this corrosion zone is practically constant. Tests show that sodium does not expand directly on the pipe surface. Sodium sprays through mineral wool insulation, where chemical reaction between silica fibers, occluded oxygen and water vapor occur at the same time. Simultaneously, there is a diffusion phenomenon of liquid Na droplets on the mineral wool fibers. The study allows to prove the electrochemical nature of the corrosion. The excess liquid Na, spraying as droplets induces an anodic dissolution mechanism by differential aeration. This phenomenon explains the random microscopic and macroscopic aspects of material removal. (authors). 1 ref., 16 figs

  16. Aging of cast duplex stainless steels in LWR systems

    International Nuclear Information System (INIS)

    A program is being conducted to investigate the significance of in-service embrittlement of cast duplex stainless steels under light-water reactor operating conditions. The existing data are evaluated to determine the expected embrittlement of cast components during the operating lifetime of reactors and to define the objectives and scope of the investigation. This presentation describes the status of the program. Data for the metallurgical characterization of the various cast stainless steels used in the investigation are presented. Charpy impact tests on short-term aged material indicate that CF-3 stainless steels are less susceptible to embrittlement than CF-8 or CF-8M stainless steels. Microstructural characterization of cast stainless steels that were obtained from Georg Fischer Co. and aged for up to 70,000 h at 300, 350, and 4000C reveals the formation of four different types of precipitates that are not α'. Embrittlement of the ferrite phase is primarily due to pinning of the dislocations by two of these precipitates, designated as Type M and Type X. The ferrite phase is embrittled after approx. 8 y at 3000C and shows cleavage fracture. Examination of the fracture surfaces of the impact-test specimens indicates that the toughness of the long-term aged material is determined by the austenite phase. 8 figures, 3 tables

  17. Aging of cast duplex stainless steels in LWR systems

    International Nuclear Information System (INIS)

    A program is being conducted to investigate the significance of in-service embrittlement of cast duplex stainless steels operating conditions. The existing data are evaluated to determine the expected embrittlement of cast components during the operating lifetime of reactors and to define the objectives and scope of the investigation. This presentation describes the status of the program. Data for the metallurgical characterization of the various cast stainless steels used in the investigation are presented. Charpy impact tests on short-term aged material indicate that CF-3 stainless steels are less susceptible to embrittlement than CF-8 or CF-8M stainless steels. Microstructural characterization of cast stainless steels that were obtained from Georg Fischer Co. and aged for up to 70 000 h at 300, 350 and 4000C reveals the formation of four different types of precipitates that are not α'. Embrittlement of the ferrite phase is primarily due to pinning of the dislocations by two of these precipitates, designated as Type M and Type X. The ferrite phase is embrittled after proportional 8 y at 3000C and shows cleavage fracture. Examination of the fracture surfaces of the impact test specimens indicates that the toughness of the long-term aged material is determined by the austenitic phase. (orig./HP)

  18. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2011-01-01

    White Cast Iron (Ⅰ) White cast iron or ‘white iron' refers to the type of cast iron in which all of the carbon exists as carbide;there is no graphite in the as-cast structure and the fractured surface shows a white colour.White cast iron can be divided in three classes:· Normal white cast iron — this iron contains only C,Si,Mn,P and S,with no other alloying elements.· Low-alloy white cast iron — the total mass fraction of alloying elements is less than 5%.

  19. Long time high temperature strain gage measurements on pipes and dissimilar welds

    International Nuclear Information System (INIS)

    In the dissimilar weld program, a pipe consisting of several ferritic (X20 CrMoV 121) and Austenitic (X10 NiCrAlTi 32 20) pipe sections with dissimilar welds is exposed to combined internal pressure temperature loads. In long tern experiments lasting 20,000 hours, both capacitative high temperature strain gauges and resistance HT DMS are used to measure strain. There is then a check of the long term stability of the measuring system. The experiments are carried out for proving the integrity of the water/steam circuit of an HTR. (DG)

  20. A fatigue analysis including environmental effects for a pipe system in a Swedish BWR

    International Nuclear Information System (INIS)

    A BWR feed water piping system (austenitic steel) has been analyzed with two different fatigue curves and environmental factors. Original fatigue curve from ASME is compared to a new fatigue curve; ANL. The influence of environmental correction factors (Fen) is studied further for the piping system. It is noted that the results apply for this particular system, and general conclusions should be cautiously drawn. Typical for this system is that all dominant loads are within the low-cycle regime. This implies that the change of fatigue curve only leads to limited increases in usage factors. Larger changes can occur if larger number of cycles is within the high-cycle regime

  1. Centrifugal casting process

    International Nuclear Information System (INIS)

    Centrifugal casting is not one of the most common metalforming techniques, but there are a few applications of great value, for example in gas cooled reactors. In this article a few examples of these applications are discussed

  2. Probabilistic assessment of crack initiation in a piping under thermal-fatigue loading

    International Nuclear Information System (INIS)

    The European research project THERFAT concerned with an evaluation of the thermal fatigue phenomenon in mixing tees of austenite piping. Computational results obtained for conservatively selected boundary conditions revealed high stresses in a mixing tee and, correspondingly, a possibility of fatigue damage. In this paper, statistical methods are applied to properly account for the scatter and uncertainties in the input data, leading to a probabilistic assessment of the component lifetime. Results are compared with previous predictions based on a deterministic approach. (orig.)

  3. Heat Pipe Planets

    Science.gov (United States)

    Moore, William B.; Simon, Justin I.; Webb, A. Alexander G.

    2014-01-01

    When volcanism dominates heat transport, a terrestrial body enters a heat-pipe mode, in which hot magma moves through the lithosphere in narrow channels. Even at high heat flow, a heat-pipe planet develops a thick, cold, downwards-advecting lithosphere dominated by (ultra-)mafic flows and contractional deformation at the surface. Heat-pipes are an important feature of terrestrial planets at high heat flow, as illustrated by Io. Evidence for their operation early in Earth's history suggests that all terrestrial bodies should experience an episode of heat-pipe cooling early in their histories.

  4. Heat Pipe Materials Compatibility

    Science.gov (United States)

    Eninger, J. E.; Fleischman, G. L.; Luedke, E. E.

    1976-01-01

    An experimental program to evaluate noncondensable gas generation in ammonia heat pipes was completed. A total of 37 heat pipes made of aluminum, stainless steel and combinations of these materials were processed by various techniques, operated at different temperatures and tested at low temperature to quantitatively determine gas generation rates. In order of increasing stability are aluminum/stainless combination, all aluminum and all stainless heat pipes. One interesting result is the identification of intentionally introduced water in the ammonia during a reflux step as a means of surface passivation to reduce gas generation in stainless-steel/aluminum heat pipes.

  5. Introduction to Heat Pipes

    Science.gov (United States)

    Ku, Jentung

    2015-01-01

    This is the presentation file for the short course Introduction to Heat Pipes, to be conducted at the 2015 Thermal Fluids and Analysis Workshop, August 3-7, 2015, Silver Spring, Maryland. NCTS 21070-15. Course Description: This course will present operating principles of the heat pipe with emphases on the underlying physical processes and requirements of pressure and energy balance. Performance characterizations and design considerations of the heat pipe will be highlighted. Guidelines for thermal engineers in the selection of heat pipes as part of the spacecraft thermal control system, testing methodology, and analytical modeling will also be discussed.

  6. The thermal fatigue behaviour of creep-resistant Ni-Cr cast steel

    Directory of Open Access Journals (Sweden)

    B. Piekarski

    2007-12-01

    Full Text Available The study gives a summary of the results of industrial and laboratory investigations regarding an assessment of the thermal fatigue behaviour of creep-resistant austenitic cast steel. The first part of the study was devoted to the problem of textural stresses forming in castings during service, indicating them as a cause of crack formation and propagation. Stresses are forming in carbides and in matrix surrounding these carbides due to considerable differences in the values of the coefficients of thermal expansion of these phases. The second part of the study shows the results of investigations carried out to assess the effect of carbon, chromium and nickel on crack resistance of austenitic cast steel. As a criterion of assessment the amount and propagation rate of cracks forming in the specimens as a result of rapid heating followed by cooling in running water was adopted. Tests were carried out on specimens made from 11 alloys. The chemical composition of these alloys was comprised in a range of the following values: (wt-%: 18-40 %Ni, 17-30 %Cr, 1.2-1.6%Si and 0.05-0.6 %C. The specimens were subjected to 75 cycles of heating to a temperature of 900oC followed by cooling in running water. After every 15 cycles the number of the cracks was counted and their length was measured. The results of the measurements were mathematically processed. It has been proved that the main factor responsible for an increase in the number of cracks is carbon content in the alloy. In general assessment of the results of investigations, the predominant role of carbon and of chromium in the next place in shaping the crack behaviour of creep-resistant austenitic cast steel should be stressed. Attention was also drawn to the effect of high-temperature corrosion as a factor definitely deteriorating the cast steel resistance to thermal fatigue.

  7. Study on the microstructure and mechanical properties of medium carbon Cr-Si-Mn-Mo-V steel for cast inserted dies

    Directory of Open Access Journals (Sweden)

    HAO Xiao-yan

    2005-11-01

    Full Text Available The microstructure and mechanical properties of cast inserted dies for automobile covering components were studied. The results show that the as-cast microstructures of cast inserted dies are composed of pearlite, martensite,bainite, and austenite; and that the annealed microstructure is granular pearlite. The mechanical properties of cast inserted dies approach that of forged inserted dies. The tensile strength is 855 MPa, the elongation is 16%, the impact toughness is 177 J/cm2, and the hardness after annealing and quenching are HRC 19 and HRC 60-62. In addition, the cast inserted dies have good hardenability. The depth of the hardening zone and the hardness after flame quenching satisfy the operating requirements. The cast inserted dies could completely replace the forged inserted dies for making the dies of automobile covering components.

  8. Application of narrow groove welding process to nuclear pipes

    International Nuclear Information System (INIS)

    Experiments on narrow groove welding with a single string bead deposition per layer were performed using automatic orbital TIG welding equipment, and the narrow groove shape and welding conditions were optimized for stainless steel and carbon steel pipes. The characteristics of narrow groove weld joints of these materials were investigated in the areas of metallurgical structure and mechanical properties. The process of one bead per layer was found to produce a good homogeneous weld and the total weld has the same micro structure between two regular fusion lines and, therefore, uniform mechanical properties. Based on these test results, the narrow groove welding process was applied to butt weld joints for austenitic stainless steel pipe with a large diameter. (author)

  9. Skeleton castings dynamic load resistance

    OpenAIRE

    M. Cholewa; J. Szajnar; T. Szuter

    2013-01-01

    Purpose: The article is to show selected results of research in a field of new type of cast spatial composite reinforcements. This article shows skeleton casting case as a particular approach to continuous, spatial composite reinforcement.Design/methodology/approach: The research is concerning properties of cast spatial microlattice structures called skeleton castings. In this paper results of impact test of skeleton casting with octahedron elementary cell were shown. The selection of interna...

  10. Numerical simulation of low pressure die-casting aluminum wheel

    Institute of Scientific and Technical Information of China (English)

    Mi Guofa; Liu Xiangyu; Wang Kuangfei; Fu Hengzhi

    2009-01-01

    The FDM numerical simulation software, ViewCast system, was employed to simulate the low pressure die casting (LPDC) of an aluminum wheel. By analyzing the mold-filling and solidification stage of the LPDC process, the distribution of liquid fraction, temperature field and solidification pattern of castings were studied. The potential shrinkage defects were predicted to be formed at the rim/spoke junctions, which is in consistence with the X-ray detection result. The distribution pattern of the defects has also been studied. A solution towards reducing such defects has been presented. The cooling capacity of the mold was improved by installing water pipes both in the side mold and the top mold. Analysis on the shrinkage defects under forced cooling mode proved that adding the cooling system in the mold is an effective method for reduction of shrinkage defects.

  11. Numerical simulation of low pressure die-casting aluminum wheel

    Directory of Open Access Journals (Sweden)

    Mi Guofa

    2009-02-01

    Full Text Available The FDM numerical simulation software, ViewCast system, was employed to simulate the low pressure die casting (LPDC of an aluminum wheel. By analyzing the mold-fi lling and solidifi cation stage of the LPDC process, the distribution of liquid fraction, temperature field and solidification pattern of castings were studied. The potential shrinkage defects were predicted to be formed at the rim/spoke junctions, which is in consistence with the X-ray detection result. The distribution pattern of the defects has also been studied. A solution towards reducing such defects has been presented. The cooling capacity of the mold was improved by installing water pipes both in the side mold and the top mold. Analysis on the shrinkage defects under forced cooling mode proved that adding the cooling system in the mold is an effective method for reduction of shrinkage defects.

  12. (Continuous casting 1985)

    Energy Technology Data Exchange (ETDEWEB)

    Wilde, R.A.

    1985-06-12

    The report covers the Continuous Casting '85 Conference including informal discussions with conference attendees. In general, the papers presented at the conference concerned an overview of continuous steel casting worldwide, state-of-the-art aspects of steel continuous casting technology including caster startup problems, modifications, control system strategies, energy use profiles, quality control aspects, steel chemistry control, refractories, operational aspects of continuous casters, etc. No papers were presented in the development of thin section or thin strip casting of steel. Informal discussions were held with several conference attendees including (1) Bernard Trentini, Executive Director of the Association Technique De La Siderurgie Francaise in Paris, France (similar to the American Iron and Steel Institute); (2) Dr. Wolfgang Reichelt and Dr. Peter Voss-Spilker both of Mannesmann Demag Huttentechnik -a continuous casting and other steel making machine builder in-lieu of meeting at their plant in Duisburg, FRG on May 31; (3) Ewan C. Hewitt of Devote McKee Corp., Sheffield, England; (4) Wilfried Heinemann, head of R D Dept. at Concast Standard AG in Zurich, Switzerland; and (5) Hideo Ueno, engineer of melting section, Mitsubishi Steel Mfg. Co. Ltd, Tokyo Japan. A visit was made to the Teesside Laboratories of British Steel Corp. for discussions of their thin section casting research program in particular and R D program in general.

  13. Casting AISI 316 steel by gel cast

    International Nuclear Information System (INIS)

    The feasibility of producing AISI 316 steel components from their powders and avoiding their compaction is analyzed. A casting technique is tested that is similar to gel casting, used for ceramic materials. In the initial stage, the process consists of the formulation of a concentrated barbotine of powdered metal in a solution of water soluble organic monomers, which is cast in a mold and polymerized in situ to form a raw piece in the shape of the cavity. The process can be performed under controlled conditions using barbotines with a high monomer content from the acrylimide family. Then, the molded piece is slowly heated until the polymer is eliminated, and it is sintered at temperatures of 1160oC to 1300oC under a dry hydrogen atmosphere, until the desired densities are attained. The density and micro structure of the materials obtained are compared with those for the materials compacted and synthesized by the conventional processes. The preliminary results show the feasibility of the process for the production of certain kinds of structural components (CW)

  14. Reeling of tight fit pipe

    OpenAIRE

    Focke, E.S.

    2007-01-01

    If it would be possible to install Tight Fit Pipe by means of reeling, it would be an attractive new option for the exploitation of offshore oil and gas fields containing corrosive hydrocarbons. Tight Fit Pipe is a mechanically bonded double walled pipe where a corrosion resistant alloy liner pipe is mechanically fitted inside a carbon steel outer pipe through a thermo-hydraulic manufacturing process. Reeling is a fast method of offshore pipeline installation where a pipe is spooled on a reel...

  15. Gas explosions in process pipes

    OpenAIRE

    Kristoffersen, Kjetil

    2004-01-01

    In this thesis, gas explosions inside pipes are considered. Laboratory experiments and numerical simulations are the basis of the thesis. The target of the work was to study gas explosions in pipes and to develop numer- ical models that could predict accidental gas explosions inside pipes. Experiments were performed in circular steel and plexiglass pipes. The steel pipes have an inner diameter of 22.3 mm and lengths of 1, 2, 5 and 11 m. The plexiglass pipe has an inner diame...

  16. Technology of processing furnaces for refining and petrochemistry. Criteria for the choice of materials for pipes of bundles

    Energy Technology Data Exchange (ETDEWEB)

    Pingeot, M. (ENSEEG, Grenoble (France))

    1981-12-01

    The present state of technology is examined for the determination of steel types as a function of service conditions: temperature, pressure and corrosion. Austenitic structure, grain size, carbon content and additional elements are studied for creep resistance at a temperature of 1000 and a pressure up to 300 atmospheres. Influence of hydrogen, sulfhydric acid, polythionic acids, naphtenic acids and carburation on internal corrosion of pipes is examined and also oxidation and attack by fuel oil ashes of the external surfaces for different types of steels. Precautions to be taken for welding of chromium mobybdenum steels and austenitic stainless steels are indicated.

  17. The development of high strength corrosion resistant precipitation hardening cast steels

    Science.gov (United States)

    Abrahams, Rachel A.

    Precipitation Hardened Cast Stainless Steels (PHCSS) are a corrosion resistant class of materials which derive their properties from secondary aging after a normalizing heat treatment step. While PHCSS materials are available in austenitic and semi-austenitic forms, the martensitic PHCSS are most widely used due to a combination of high strength, good toughness, and corrosion resistance. If higher strength levels can be achieved in these alloys, these materials can be used as a lower-cost alternative to titanium for high specific strength applications where corrosion resistance is a factor. Although wrought precipitation hardened materials have been in use and specified for more than half a century, the specification and use of PHCSS has only been recent. The effects of composition and processing on performance have received little attention in the cast steel literature. The work presented in these investigations is concerned with the experimental study and modeling of microstructural development in cast martensitic precipitation hardened steels at high strength levels. Particular attention is focused on improving the performance of the high strength CB7Cu alloy by control of detrimental secondary phases, notably delta ferrite and retained austenite, which is detrimental to strength, but potentially beneficial in terms of fracture and impact toughness. The relationship between age processing and mechanical properties is also investigated, and a new age hardening model based on simultaneous precipitation hardening and tempering has been modified for use with these steels. Because the CB7Cu system has limited strength even with improved processing, a higher strength prototype Fe-Ni-Cr-Mo-Ti system has been designed and adapted for use in casting. This prototype is expected to develop high strengths matching or exceed that of cast Ti-6Al-4V alloys. Traditional multicomponent constitution phase diagrams widely used for phase estimation in conventional stainless steels

  18. Piping research program plan

    International Nuclear Information System (INIS)

    This document presents the piping research program plan for the Structural and Seismic Engineering Branch and the Materials Engineering Branch of the Division of Engineering, Office of Nuclear Regulatory Research. The plan describes the research to be performed in the areas of piping design criteria, environmentally assisted cracking, pipe fracture, and leak detection and leak rate estimation. The piping research program addresses the regulatory issues regarding piping design and piping integrity facing the NRC today and in the foreseeable future. The plan discusses the regulatory issues and needs for the research, the objectives, key aspects, and schedule for each research project, or group of projects focussing of a specific topic, and, finally, the integration of the research areas into the regulatory process is described. The plan presents a snap-shot of the piping research program as it exists today. However, the program plan will change as the regulatory issues and needs change. Consequently, this document will be revised on a bi-annual basis to reflect the changes in the piping research program. (author)

  19. These Pipes Are "Happening"

    Science.gov (United States)

    Skophammer, Karen

    2010-01-01

    The author is blessed with having the water pipes for the school system in her office. In this article, the author describes how the breaking of the pipes had led to a very worthwhile art experience for her students. They practiced contour and shaded drawing techniques, reviewed patterns and color theory, and used their reasoning skills--all while…

  20. Transients in pipes

    International Nuclear Information System (INIS)

    The motion of a fluid in a pipe is commonly modeled utilizing the one space dimension conservation laws of mass and momentum. The development of shocks and spikes utilizing the uniform sampling method is studied. The effects of temperature variations and friction are compared for gas pipes. (Author)

  1. Heat pipe technology issues

    International Nuclear Information System (INIS)

    Critical high temperature, high power applications in space nuclear power designs are near the current state of the art of heat pipe technology in terms of power density, operating temperature, and lifetime. Recent heat pipe development work at Los Alamos National Laboratory has involved performance testing of typical space reactor heat pipe designs to power levels in excess of 19 kW/cm2 axially and 300 W/cm2 radially at temperatures in the 1400 to 1500 K range. Operation at conditions in the 10 kW/cm2 range has been sustained for periods of up to 1000 hours without evidence of performance degradation. The effective length for heat transport in these heat pipes was from 1.0 to 1.5 M. Materials used were molybdenum alloys with lithium employed as the heat pipe operating fluid. Shorter, somewhat lower power, molybdenum heat pipes have been life tested at Los Alamos for periods of greater than 25,000 hours at 1700 K with lithium and 20,000 hours at 15000K with sodium. These life test demonstrations and the attendant performance limit investigations provide an experimental basis for heat pipe application in space reactor design and represent the current state-of-the-art of high temperature heat pipe technology

  2. Austenitic stainless steels with cryogenic resistance

    International Nuclear Information System (INIS)

    The most used austenitic stainless steels are alloyed with chromium and nickel and have a reduced carbon content, usually lower than 0.1 % what ensures corresponding properties for processing by plastic deformation at welding, corrosion resistance in aggressive environment and toughness at low temperatures. Steels of this kind alloyed with manganese are also used to reduce the nickel content. By alloying with manganese which is a gammageneous element one ensures the stability of austenites. Being cheaper these steels may be used extensively for components and equipment used in cryogenics field. The best results were obtained with steels of second group, AMnNi, in which the designed chemical composition was achieved, i.e. the partial replacement of nickel by manganese ensured the toughness at cryogenic temperatures. If these steels are supplementary alloyed, their strength properties may increase to the detriment of plasticity and toughness, although the cryogenic character is preserved

  3. Grain boundary strengthening in austenitic nitrogen steels

    International Nuclear Information System (INIS)

    The effect of nitrogen and carbon on the strengthening of the austenitic steel Cr18Ni16Mn10 by grain boundaries is studied. It is established in accordance with previous results that contrary to carbon nitrogen increases the coefficient k in the Hall-Petch equation markedly. Because of a pronounced planar slip induced by nitrogen and the absence of any noticeable segregation of nitrogen atoms at the grain boundaries, nitrogen austenite presents an excellent object for testing different existing models of grain boundary strengthening (pile-up, grain boundary dislocation sources, work hardening theories). Based on the analysis of available data and measurements of interaction between nitrogen (carbon) atoms and dislocations it is shown that the nitrogen effect can be attributed to a strong blocking of dislocation sources in grains adjacent to those where the slip started. (orig.)

  4. Sintered Nickel Powder Wicks for Flat Vertical Heat Pipes

    OpenAIRE

    Geir Hansen; Erling Næss; Kolbeinn Kristjansson

    2015-01-01

    The fabrication and performance of wicks for flat heat pipe applications produced by sintering a filamentary nickel powder has been investigated. Tape casting was used as an intermediate step in the wick production process. Thermogravimetric analysis was used to study the burn-off of the organic binder used and to study the oxidation and reduction processes of the nickel. The wicks produced were flat, rectangular and intended for liquid transport in the upwards vertical direction. Rate-of-ris...

  5. Reliability of welded austenitic stainless steel containing base metal delta ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Shalaby, Hamdy M. [Kuwait Institute for Scientific Research (Kuwait)

    2004-07-01

    The paper presents the results of a failure case study carried out on welded 304L stainless steel (SS) pipeline of waste gas header (WGH). The environment inside the WGH was mainly wet steam with hydrocarbons, H{sub 2}S, oxygen, CO{sub 2}, organic acids, and organic chlorides. The outside pipe wall temperature was 91-97 deg C. The failure of the pipe was at the heat-affected zone (HAZ). The study was made on four welded pipeline samples, three of which were in service. The pipe samples were welded using three different techniques that included autogenous gas tungsten arc, shielded metal arc, and flux core arc. The investigation revealed that cracking at HAZ was due to base metal delta ferrite decay accompanied with sigma phase formation due to high heat input during welding. However, the morphology and orientation of the cracks suggested that stress-rupture and stress corrosion cracking had occurred. The presence of base metal delta ferrite made all used welding procedures un-successful. The study concluded that utilization of delta ferrite free austenitic SS should eliminate the problem. (author)

  6. The effect of retained austenite on steel fracture toughness

    International Nuclear Information System (INIS)

    This paper is an attempt of reviewing the outlooks about the favourable influence of retained austenite on fracture toughness of tool steels. The tests were performed on the samples made of the new 70HG2MF steel in which the fraction of retained austenite was changed by subquenching or by changing the austenitizing temperature. It was revealed that in the subquenched samples retained austenite affects strongly the increase of fracture toughness. On the other hand, however, in the samples austenitized at growing temperatures, the effect of this phase on fracture toughness is not so univocal since not only the volume fraction of retained austenite is subjected to changes but also the character of fractures and the grain size. (author)

  7. Corrosion of austenitic steel in sodium loops

    International Nuclear Information System (INIS)

    The possibility of predicting corrosion effects for austenitic steel exposed to liquid sodium with an analytical diffusion model is presented. The analytically predicated corrosion effects are compared with experimental measurements of corrosion effects achieved in an accurately controlled sodium loop. The diffusion model is described with figures showing disc sample weight loss and sodium flow guidance tube chromium and nickel profiles. Finally, the concentration profile in the fuel rod wall (diffusion model) is presented for iron, chromium and nickel

  8. Tritium in austenitic stainless steel vessels

    International Nuclear Information System (INIS)

    Austenitic stainless steels are normally recommended for components of hydrogen-handling equipment in applications where high in-service reliability is required. The literature leading to this recommendation is reviewed, and it is shown that AISI Type 316L stainless is particularly suitable for use in tritium-handling and storage systems. When made of this steel, the storage vessels will be extremely resistant to any degradation from tritium in both routine and accident conditions. (author)

  9. Oscillating heat pipes

    CERN Document Server

    Ma, Hongbin

    2015-01-01

    This book presents the fundamental fluid flow and heat transfer principles occurring in oscillating heat pipes and also provides updated developments and recent innovations in research and applications of heat pipes. Starting with fundamental presentation of heat pipes, the focus is on oscillating motions and its heat transfer enhancement in a two-phase heat transfer system. The book covers thermodynamic analysis, interfacial phenomenon, thin film evaporation,  theoretical models of oscillating motion and heat transfer of single phase and two-phase flows, primary  factors affecting oscillating motions and heat transfer,  neutron imaging study of oscillating motions in an oscillating heat pipes, and nanofluid’s effect on the heat transfer performance in oscillating heat pipes.  The importance of thermally-excited oscillating motion combined with phase change heat transfer to a wide variety of applications is emphasized. This book is an essential resource and learning tool for senior undergraduate, gradua...

  10. Long-term embrittlement of cast duplex stainless steels in LWR systems

    International Nuclear Information System (INIS)

    This progress report summarizes work performed by Argonne National Laboratory on long-term embrittlement of cast duplex stainless steels in LWR systems during the six months from April to September 1987. Microstructural studies were conducted to investigate the kinetics of spinodal decomposition and G-phase and γ2 precipitation of CF-8 and CF-8M grades of cast stainless steel. The results indicate that the presence of Mo in CF-8M steel accelerates spinodal decomposition as well as G-phase and γ2 precipitation. Examination of the long-term-aged CF-8M steels also revealed a ''spinodal-like'' decomposition of the austenite caused by segregation of Fe and Ni in the matrix. Preliminary results indicate that local regions of austenite are significantly hardened by the decomposition. Charpy-impact, tensile, and J-R curve data are presented for several heats of cast stainless steels aged at temperatures between 320 and 450 degree C for times up to 10,000 h. The results indicate that concentrations of carbon and nitrogen in the steel and the ferrite content and spacing are important parameters in controlling low-temperature embrittlement. The existing correlations for estimating the extent and kinetics of embrittlement do not accurately represent the properties of different grades and compositions of cast stainless steel after thermal aging. 36 refs., 24 figs., 5 tabs

  11. Phase Transformations in Cast Duplex Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Yoon-Jun Kim

    2004-12-19

    Duplex stainless steels (DSS) constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as {sigma} and {chi} can also form during casting or high-temperature processing and can degrade the properties of the DSS. This research was initiated to develop time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams of two types of cast duplex stainless steels, CD3MN (Fe-22Cr-5Ni-Mo-N) and CD3MWCuN (Fe-25Cr-7Ni-Mo-W-Cu-N), in order to understand the time and temperature ranges for intermetallic phase formation. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy (SEM, TEM) and wavelength dispersive spectroscopy (WDS). The kinetics of intermetallic-phase ({sigma} + {chi}) formation were analyzed using the Johnson-Mehl-Avrami (MA) equation in the case of isothermal transformations and a modified form of this equation in the case of continuous cooling transformations. The rate of intermetallic-phase formation was found to be much faster in CD3MWCuN than CD3MN due mainly to differences in the major alloying contents such as Cr, Ni and Mo. To examine in more detail the effects of these elements of the phase stabilities; a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc. In general, {sigma} was stabilized with increasing Cr addition and {chi} by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in

  12. Phase transformations in cast duplex stainless steels

    Science.gov (United States)

    Kim, Yoon-Jun

    Duplex stainless steels (DSS) constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as sigma (sigma) and chi (chi) can also form during casting or high-temperature processing and can degrade the properties of the DSS. This research was initiated to develop time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams of two types of cast duplex stainless steels, CD3MN (Fe-22Cr-5Ni-Mo-N) and CD3MWCuN (Fe-25Cr-7Ni-Mo-W-Cu-N), in order to understand the time and temperature ranges for intermetallic phase formation. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy (SEM, TEM) and wavelength dispersive spectroscopy (WDS). The kinetics of intermetallic-phase (sigma + chi) formation were analyzed using the Johnson-Mehl-Avrami (JMA) equation in the case of isothermal transformations and a modified form of this equation in the case of continuous cooling transformations. The rate of intermetallic-phase formation was found to be much faster in CD3MWCuN than CD3MN due mainly to differences in the major alloying contents such as Cr, Ni and Mo. To examine in more detail the effects of these elements of the phase stabilities, a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc. In general, a was stabilized with increasing Cr addition and chi by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in

  13. Electron beam welding of austenitic stainless steel

    International Nuclear Information System (INIS)

    Austenitic stainless steel is used for liquid metal-cooled fast breeder reactors with operating temperature of about 550 deg C, because its elevated temperature properties are excellent and the results of use are abundant. The welded joints in LMFBRs require high degree of safety, and the application of electron beam welding is studied to make welding joints of high quality. When the inelastic deformation in a certain limit is allowed as prescribed in the ASME Code, Case 1592, the elevated temperature properties of the welded joints of structures are particularly important. The materials tested were 10 mm thick plates of SUS 304, SUS 316 and SUS 321 steels, and 150 kV - 40 mA electron beam welder was employed. The method of welding was one side, one pass Uranami welding, and first, the appropriate welding conditions were decided. Elevated temperature tensile test was carried out on the parent materials and welded joints by electron beam welding and coated arc welding. Creep rupture test and elevated temperature fatigue test were also carried out. In EB-welded austenitic stainless steel, delta ferrite is scattered finely in austenite, and its quantity is very small and less than 1.5%. The tensile strength and 0.2% proof stress of EB-welded joints are almost same as those of parent materials. The creep rupture and fatigue properties of the joints are also close to those of parent materials. (Kako, I.)

  14. Precipitation effects in austenitic stainless weld metals

    International Nuclear Information System (INIS)

    Creep-rupture specimen of similar welded joints of X6CrNi 18 11 (1.4948/AISI 304) and X6CrNiMo 17 13 (1.4919/AISI 316) show only low elongation after longtime testing. The reason for this loss of ductility was found by metallographic investigations. The weld metal of five joints had ferrite contents from 3 to 7.5%, due to a primary ferritic solidification. During creep testing in the temperature range from 500 to 800deg C carbide precipitation takes place at the austenite-ferrite grain boundaries, because delta ferrite is not in a state of equilibrium at these temperatures. After carbon has been used up, the remaining delta ferrite changes into sigma phase, if its alloying element content is high enough. In the upper temperature range, coagulation of sigma phase is dominating. At these large particles grain boundary migration is hindered. During the grain boundary sliding sigma phase particles break and initiate creep cracks. In fully austenintic weld metal sigma precipitation starts at austenite - austenite grain boundaries. During creep testing, void formation starts at sigma particles. Growing of voids leads to grain separations. (orig.)

  15. Corrosion and wear behavior of nickel austenitic castiron%镍奥氏体铸铁耐腐蚀及磨损行为

    Institute of Scientific and Technical Information of China (English)

    刘玉珍; 孙兰; 李长案; 熊计; 王艳芬

    2012-01-01

    针对高镍奥氏体铸铁成本高的特点,拟通过用价格低廉的锰代替价格昂贵的镍,并调整Cu,Cr和Si等元素含量,制备低镍奥氏体铸铁.研究镍铸铁在5%(质量分数)HCI溶液中的腐蚀行为和在3.5%(质量分数)NaCl溶液中的电化学腐蚀行为及在干摩擦条件下的耐磨损性能.研究结果表明:在5% HC1溶液中,低镍铸铁耐腐蚀性能与高镍铸铁的耐腐蚀性能相当;同时,所有镍铸铁试样在3.5% NaCl盐溶液中的电化学腐蚀行为都出现了氧扩散的平台,并且自腐蚀电流密度与自腐蚀电位随着Ni,Cr和Cu含量的降低而不同程度地增加;在干摩擦条件下,低镍铸铁的耐磨损性能接近或高于高镍铸铁的耐磨损性能,其主要的磨损机制是黏着磨损,同时还存在疲劳磨损和磨粒磨损.%Based on the fact that application of the high-nickel austenitic cast iron results in high cost, the low-nickel austenitic cast iron was prepared by reducing the nickel content of the cast iron with substitution of Mn for Ni and simultaneously controlling the content of Cu, Cr and Si. The corrosion behavior of low-nickel austenitic cast iron was studied in 5%(mass fraction) HC1 solution. At the same time, the electrochemical behavior in 3.5%(mass fraction) NaCl solution and the wear resistance under dry friction condition were also investigated. The results show that the corrosion resistance of the low-nickel austenitic cast iron in 5% HC1 solution is very close to that of high-nickel austenitic cast iron. In the polarization curve of all nickel austenitic cast iron samples in 3.5%NaCl solution, there emerges the platform of oxygen diffusion. With the decrease of the addition of Ni, Cr and Cu, the corrosion current density and the corrosion potential are increased to some extent. Under the conditions of the dry friction, the wear resistance of low-nickel cast iron is similar or a little higher than that of high-nickel cast iron. The adhesive

  16. Drill pipe downhole unthreading apparatus

    International Nuclear Information System (INIS)

    This paper describes an apparatus for unthreading a threaded connection in a drill string. It comprises: an elongate shaft; fluid powered means for moving the shaft in repeated movement between first and second positions; upper and lower mandrels supporting the shaft and exposed to joints making up the drill string, the mandrels joining together to permit rotation therebetween; upper and lower pipe gripping means cooperatively engaging pipe joints in the drill string wherein the upper pipe gripping means engages a pipe joint above a threaded connection in the pipe string and the lower pipe gripping means engages a pipe joint below the threaded connection in the pipe string; and means coupling the shaft to impart repeated movement through the upper and lower mandrels and pipe gripping means to the pipe joints so that the threaded connection in the pipe string is rotated to unthread

  17. The CAST experiment

    International Nuclear Information System (INIS)

    CAST (CERN Axion Solar Telescope) is a helioscope looking for axions coming from the solar core to the Earth. The experiment, located at CERN, is based on the Primakoff effect and uses a magnetic field of 9 Tesla provided by a decommissioned LHC magnet. CAST is able to follow the Sun during sunrise and sunset and therefore three X-ray detectors are mounted on both ends of the magnet waiting for a photon from axion-to-photon conversion due to the Primakoff effect. During its first phase, which concluded in 2004, CAST has been looking for axions with masses up to 0.02 eV. CAST's second phase manages to re-establish the coherence needed to scan for axions with masses up to 1.16 eV by using a buffer gas. This technique enables the experiment to look into the theoretical regions for axions. During the years 2005 and 2006, the use of 4He in CAST has already provided coherence in order to look for axions with masses up to 0.4 eV

  18. Additional grain refinement in recrystallization controlled rolling of Ti-microalloyed steels processed by near-net-shape casting technology

    International Nuclear Information System (INIS)

    This paper analyzes the recrystallization kinetics in Ti-microalloyed steels processed using 'beam blank' casting technology. The faster solidification rates associated with this technology brings a finer precipitation of TiN particles which are very effective in controlling austenite grain growth during hot working. Furthermore, these small precipitates have been shown to delay static and dynamic recrystallization. The finer the precipitates the higher the delay in recrystallization. Nevertheless, beyond particle size and distribution, the level of delay is very dependent on microstructure (above all austenite grain size) and deformation conditions (strain and temperature). This paper studies the effects of this recrystallization delay on the microstructure evolution during hot rolling. Special attention was paid to the study of the occurrence of partial recrystallization during the final stages of rolling, which could lead to the presence of mixed microstructures before transformation. The possibility of achieving an additional austenite grain size refinement prior to transformation was evaluated

  19. Postservice examination of weld discontinuities in large diameter stainless steel piping

    International Nuclear Information System (INIS)

    Metallurgical examination of pipe-to-pipe weld regions in large-diameter pipe removed from nuclear reactor service has revealed the presence of small fusion zone (FZ) discontinuities. The pipe was fabricated in the 1950's from AISI Type 304 stainless steel and welded using Type 308 filler material. The objectives of the investigation were to characterize discontinuities in weld FZ, determine the mechanisms of formation, establish the tendency for in-service propagation, and to assess the impact of FZ discontinuities on mechanical properties and service life. To accomplish this, UT and Pt were performed in weld areas to identify discontinuities and their location. Coupons were cut for metallography, optical microscopy, and, as necessary, electron microscopy (scanning electron microscopy/energy-dispersive spectroscopy [SEM/EDS]). Discontinuities which were observed in the FZ included one case of IGSCC propagation, lack-of-penetration (LOP), lack-of-fusion (LOF), underfill at the weld root, microfissures, and inclusions. Some of the discontinuities, such as microfissures, were found to have been extended by a crevice corrosion mechanism, predominantly when in fully duplex (austenite/δ ferrite) microstructures. When discontinuities such as LOF bridged austenitic and duplex structures and were open to the ID, some cracks were extended by intergranular stress corrosion, especially in the austenitic HAZ, where some grain dropping occurred. This work showed that the weld discontinuities were generally present from the time of fabrication and were most frequent in near-ID surface regions. Only those discontinuities which were open to the ID surface showed any propagation, but they did not impact the service life or structural integrity of the piping. Therefore, the in-service inspection program should continue to concentrate on IGSCC in the weld HAZ regions

  20. Crystallography of lath martensite and stabilization of retained austenite

    Energy Technology Data Exchange (ETDEWEB)

    Sarikaya. M.

    1982-10-01

    TEM was used to study the morphology and crystallography of lath martensite in low and medium carbon steels in the as-quenched and 200/sup 0/C tempered conditions. The steels have microduplex structures of dislocated lath martensite and continuous thin films of retained austenite at the lath interfaces. Stacks of laths form the packets which are derived from different (111) variants of the same austenite grain. The residual parent austenite enables microdiffraction experiments with small electron beam spot sizes for the orientation relationships (OR) between austenite and martensite. All three most commonly observed ORs, namely Kurdjumov-Sachs, Nishiyama-Wassermann, and Greninger-Troiano, operate within the same sample.

  1. Crystallography of lath martensite and stabilization of retained austenite

    International Nuclear Information System (INIS)

    TEM was used to study the morphology and crystallography of lath martensite in low and medium carbon steels in the as-quenched and 2000C tempered conditions. The steels have microduplex structures of dislocated lath martensite and continuous thin films of retained austenite at the lath interfaces. Stacks of laths form the packets which are derived from different [111] variants of the same austenite grain. The residual parent austenite enables microdiffraction experiments with small electron beam spot sizes for the orientation relationships (OR) between austenite and martensite. All three most commonly observed ORs, namely Kurdjumov-Sachs, Nishiyama-Wassermann, and Greninger-Troiano, operate within the same sample

  2. Accumulation and modeling of particles in drinking water pipe fittings

    Directory of Open Access Journals (Sweden)

    K. Neilands

    2012-09-01

    Full Text Available The effect of pipe fittings (mainly T-pieces on particle accumulation in drinking water distribution networks were shown in this work. The online measurements of flow and turbidity for cast iron, polyethylene and polyvinyl chloride pipe sections were linked with analysis of pipe geometry. Up to 0.29 kg of the total amount mobilized in T-pieces ranging from DN 100/100–DN 250/250. The accumulated amount of particles in fittings was defined as J and introduced into the existing turbidity model PODDS (prediction of discoloration in distribution systems proposed by Boxall et al. (2001 which describes the erosion of particles leading to discoloration events in drinking water network viz sections of straight pipes. However, this work does not interpret mobilization of particles in pipe fittings which have been considered in this article. T-pieces were the object of this study and depending of the diameter or daily flow velocity, the coefficient J varied from 1.16 to 8.02. The study showed that pipe fittings act as catchment areas for particle accumulation in drinking water networks.

  3. Final Report, Volume 1, Metallurgical Evaluation of Cast Duplex Stainless Steels and their Weldments

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Songqing; Lundin, Carl, W.; Batten, Greg, W.

    2005-09-30

    Duplex stainless steels (DSS) are being specified for chloride containing environments due to their enhanced pitting and stress corrosion cracking resistance. They exhibit improved corrosion performance over the austenitic stainless steels. Duplex stainless steels also offer improved strength properties and are available in various wrought and cast forms. Selected grades of duplex stainless steel castings and their welds, in comparison with their wrought counterparts, were evaluated, regarding corrosion performance and mechanical properties and weldability. Multiple heats of cast duplex stainless steel were evaluated in the as-cast, solution annealed (SA) static cast and SA centrifugal cast conditions, while their wrought counterparts were characterized in the SA condition and in the form of as-rolled plate. Welding, including extensive assessment of autogenous welds and a preliminary study of composite welds (shielded metal arc weld (SMAW)), was performed. The evaluations included critical pitting temperature (CPT) testing, intergranular corrosion (IGC) testing, ASTM A923 (Methods A, B and C), Charpy impact testing, weldability testing (ASTM A494), ferrite measurement and microstructural evaluations. In the study, the corrosion performances of DSS castings were characterized and assessed, including the wrought counterparts for comparison. The evaluation filled the pore of lack of data for cast duplex stainless steels compared to wrought materials. A database of the pitting corrosion and IGC behavior of cast and wrought materials was generated for a greater depth of understanding for the behavior of cast duplex stainless steel. In addition, improved evaluation methods for DSS castings were developed according to ASTM A923, A262, G48 and A494. The study revealed that when properly heat treated according to the specification, (1) DSS castings have equal or better pitting and intergranular corrosion resistance than their wrought counterparts; (2) Welding reduces the

  4. Final Report, Volume 1, Metallurgical Evaluation of Cast Duplex Stainless Steels and their Weldments

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Songqing; Lundin, Carl, W.; Batten, Greg, W.

    2005-09-30

    Duplex stainless steels (DSS) are being specified for chloride containing environments due to their enhanced pitting and stress corrosion cracking resistance. They exhibit improved corrosion performance over the austenitic stainless steels. Duplex stainless steels also offer improved strength properties and are available in various wrought and cast forms. Selected grades of duplex stainless steel castings and their welds, in comparison with their wrought counterparts, were evaluated, regarding corrosion performance and mechanical properties and weldability. Multiple heats of cast duplex stainless steel were evaluated in the as-cast, solution annealed (SA) static cast and SA centrifugal cast conditions, while their wrought counterparts were characterized in the SA condition and in the form of as-rolled plate. Welding, including extensive assessment of autogenous welds and a preliminary study of composite welds (shielded metal arc weld (SMAW)), was performed. The evaluations included critical pitting temperature (CPT) testing, intergranular corrosion (IGC) testing, ASTM A923 (Methods A, B and C), Charpy impact testing, weldability testing (ASTM A494), ferrite measurement and microstructural evaluations. In the study, the corrosion performances of DSS castings were characterized and assessed, including the wrought counterparts for comparison. The evaluation filled the pore of lack of data for cast duplex stainless steels compared to wrought materials. A database of the pitting corrosion and IGC behavior of cast and wrought materials was generated for a greater depth of understanding for the behavior of cast duplex stainless steel. In addition, improved evaluation methods for DSS castings were developed according to ASTM A923, A262, G48 and A494. The study revealed that when properly heat treated according to the specification, (1) DSS castings have equal or better pitting and intergranular corrosion resistance than their wrought counterparts; (2) Welding reduces the

  5. Heat pipe technology issues

    International Nuclear Information System (INIS)

    Recent heat pipe development work at Los Alamos National Laboratory as involved performance testing of typical space reactor heat pipe designs to power levels in excess of 19 kW/cm2 axially and 300 W/cm2 radially at temperatures in the 1400 to 15000K range. Operation at conditions in the 10 kW/cm2 range has been sustained for periods of up to 1000 hours without evidence of performance degradation. The effective length for heat transport in these heat pipes was from 1.0 to 1.5 M. Materials used were molybdenum alloys with lithium employed as the heat pipe operating fluid. Shorter, somewhat lower power density, molybdenum heat pipes have been life tested at Los Alamos for periods of greater than 25,000 hours at 17000K with lithium and 20,000 hours at 15000K with sodium. These life test demonstrations and the attendant performance limit investigations provide an experimental basis for heat pipe application in space reactor design and represent the current state-of-the-art of high temperature heat pipe technology. 9 refs., 11 figs

  6. Ultrasonic testing of large-diameter pipes and blanks

    International Nuclear Information System (INIS)

    The devices have been developed for mechanized ultrasonic control of forged-and-drilled, forged-and-ground, centrifugally cast pipes and blanks of diameter 400-1500 mm accomplished directly on a turning lathe after machining. Standard-type defectoscopes have been used as electronic block. The paper presents a simplified block diagram and describes the operation and technical characteristics of a set-up for control of large-diameter pipes. It also describes installations designed by the Central Institute of Mechanical Engineering Research for the Belgorod Boiler Plant and the Izhevsk Papermaking Machine Plant. Tests have shown that the developed equipment makes it possible to reveal reliably defects in high-alloy steel blanks and pipes

  7. Influence of rare earths on shrinkage porosity in thin walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2009-01-01

    Ductile cast iron has been cast in test bars with thickness from 2 to 10 mm. The rare earth elements La and Ce have been added to some of the castings to evaluate their influence on microstructure and shrinkage tendency. Both La and Ce increased the graphite nodule count, especially for thickness...... of 6 mm and below. La gave the best nodule size distribution with many small nodules. La had less shrinkage tendency than Ce in the 10 mm test bars. This tendency was less pronounced for the 6 and 4 mm test bars and other factors may have a large influence at these thicknesses. Increasing the...... temperature T-1, which is controlled by the growth of off-eutectic austenite dendrites, increased the shrinkage tendency....

  8. Casting Characteristics of Aluminum Die Casting Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  9. Studies on ductile unstable fracture of piping materials in light water reactors, (2)

    International Nuclear Information System (INIS)

    A pipe fracture test program has been conducted in Japan Atomic Energy Research Institute (JAERI) using austenitic stainless steel pipes and carbon steel pipes to investigate fracture behavior of the cracked pipe and to demonstrate the validity of the ''Leak Before Break'' concept for nuclear pressure boundary piping. This report describes the results of the laboratory-scale tests on center-cracked-tension (CCT) specimens machined from the 12-inch diameter Type 304 Nuclear Grade stainless steel pipe under tensile loading condition at room temperature. The program approach includes two efforts. The first phase develops J-R curve data for CCT specimens to characterize crack growth resistance. Furthermore, the flow stress obtained from these tests was applied to predict the collapse load of stainless steel pipe with a through-wall circumferential crack, based on the net-section collapse criterion. In the second phase of this program, unstable fracture experiments were conducted using compliant disc spring device. J-based tearing instability criterion was compared with the test results, and the validity of this criterion was discussed. (author)

  10. Experimenting with a "Pipe" Whistle

    Science.gov (United States)

    Stafford, Olga

    2012-01-01

    A simple pipe whistle can be made using pieces of PVC pipe. The whistle can be used to measure the resonant frequencies of open or closed pipes. A slightly modified version of the device can be used to also investigate the interesting dependence of the sound frequencies produced on the orifice-to-edge distance. The pipe whistle described here…

  11. Reeling of tight fit pipe

    NARCIS (Netherlands)

    Focke, E.S.

    2007-01-01

    If it would be possible to install Tight Fit Pipe by means of reeling, it would be an attractive new option for the exploitation of offshore oil and gas fields containing corrosive hydrocarbons. Tight Fit Pipe is a mechanically bonded double walled pipe where a corrosion resistant alloy liner pipe i

  12. Long term creep properties and microstructural evolution of ferritic and austenitic grades for USC power plants

    Energy Technology Data Exchange (ETDEWEB)

    Caminada, S.; Cumino, G. [Tenaris, Dalmine (BG) (Italy); Cipolla, L.; Di Gianfrancesco, A. [Centro Sviluppo Materiali SpA, Material and Product Directorate, Rome (Italy); Minami, Y.; Ono, T. [TenarisNKKt, R and D, Kawasaki, Kanagawa (Japan)

    2007-07-01

    The steam parameters in the new high efficiency fossil fuel power plants are continuously increasing, requiring new advanced materials with enhanced creep strength able to operate on the most severe temperature and pressure conditions. Tenaris focused on the development of ferritic-martensitic and austenitic grades for tubes and pipes applications. The product development in TenarisDalmine for the ferritic-martensitic grades has been focused on: low alloyed ASTM Grade 23 as substitute of Grade 22 for components operating at relatively low temperatures, containing 1.5% W and with quite good weldability and creep properties up to 580 C and a competitive cost; high alloyed ASTM Grade 92, an improved version of the well known Grade 91 for the superheaters, headers and other parts of the boiler operating at temperatures up to 620 C: its tempered martensitic structure offers very high creep strength and long term stability. The product development in TenarisNKKt R and D on austenitic grades has been focused on: TEMPALOY AA-1 as improved version of 18Cr8NiNbTi with the 3%Cu, showing high creep and corrosion properties, TEMPALOY A-3: a 20Cr-15Ni-Nb-N showing good creep behaviour and corrosion properties better than AA-1 due to the higher Cr content. This paper describes the Tenaris products, the process routes and the main characteristics of these steels, including the effect of shot blasting on steam oxidation properties of the austenitic grades, as well as, the R and D activities in the field of alloy design, creep tests, data assessment, microstructural analysis and damage modelling, conducted with the support of the Centro Sviluppo Materiali. (orig.)

  13. Pipe drafting and design

    CERN Document Server

    Parisher, Roy A

    2011-01-01

    Pipe Drafting and Design, Third Edition provides step-by-step instructions to walk pipe designers, drafters, and students through the creation of piping arrangement and isometric drawings. It includes instructions for the proper drawing of symbols for fittings, flanges, valves, and mechanical equipment. More than 350 illustrations and photographs provide examples and visual instructions. A unique feature is the systematic arrangement of drawings that begins with the layout of the structural foundations of a facility and continues through to the development of a 3-D model. Advanced chapters

  14. Optimization of Pipe Networks

    DEFF Research Database (Denmark)

    Hansen, C. T.; Madsen, Kaj; Nielsen, Hans Bruun

    1991-01-01

    The paper treats a piping system, where the layout of the network is given but the diameters of the pipes should be chosen among a small number of different values. The cost of realizing the system should be minimized while keeping the energy heads at the nodes above some lower limits. A new...... algorithm using successive linear programming is presented. The performance of the algorithm is illustrated by optimizing a network with 201 pipes and 172 nodes. It is concluded that the new algorithm seems to be very efficient and stable, and that it always finds a solution with a cost near the best...

  15. Quantitative evaluation of ultrasonic wave propagation in inhomogeneous anisotropic austenitic welds using 3D ray tracing method. Numerical and experimental validation

    International Nuclear Information System (INIS)

    Austenitic welds and dissimilar welds are extensively used in primary circuit pipes and pressure vessels in nuclear power plants, chemical industries and fossil fuelled power plants because of their high fracture toughness, resistance to corrosion and creep at elevated temperatures. However, cracks may initiate in these weld materials during fabrication process or stress operations in service. Thus, it is very important to evaluate the structural integrity of these materials using highly reliable non-destructive testing (NDT) methods. Ultrasonic non-destructive inspection of austenitic welds and dissimilar weld components is complicated because of anisotropic columnar grain structure leading to beam splitting and beam deflection. Simulation tools play an important role in developing advanced reliable ultrasonic testing (UT) techniques and optimizing experimental parameters for inspection of austenitic welds and dissimilar weld components. The main aim of the thesis is to develop a 3D ray tracing model for quantitative evaluation of ultrasonic wave propagation in an inhomogeneous anisotropic austenitic weld material. Inhomogenity in the anisotropic weld material is represented by discretizing into several homogeneous layers. According to ray tracing model, ultrasonic ray paths are traced during its energy propagation through various discretized layers of the material and at each interface the problem of reflection and transmission is solved. The influence of anisotropy on ultrasonic reflection and transmission behaviour in an anisotropic austenitic weld material are quantitatively analyzed in three dimensions. The ultrasonic beam directivity in columnar grained austenitic steel material is determined three dimensionally using Lamb's reciprocity theorem. The developed ray tracing model evaluates the transducer excited ultrasonic fields accurately by taking into account the directivity of the transducer, divergence of the ray bundle, density of rays and phase

  16. Acoustic energy transmission in cast iron pipelines

    Science.gov (United States)

    Kiziroglou, Michail E.; Boyle, David E.; Wright, Steven W.; Yeatman, Eric M.

    2015-12-01

    In this paper we propose acoustic power transfer as a method for the remote powering of pipeline sensor nodes. A theoretical framework of acoustic power propagation in the ceramic transducers and the metal structures is drawn, based on the Mason equivalent circuit. The effect of mounting on the electrical response of piezoelectric transducers is studied experimentally. Using two identical transducer structures, power transmission of 0.33 mW through a 1 m long, 118 mm diameter cast iron pipe, with 8 mm wall thickness is demonstrated, at 1 V received voltage amplitude. A near-linear relationship between input and output voltage is observed. These results show that it is possible to deliver significant power to sensor nodes through acoustic waves in solid structures. The proposed method may enable the implementation of acoustic - powered wireless sensor nodes for structural and operation monitoring of pipeline infrastructure.

  17. Relative merits of duplex and austenitic stainless steels for applications in the oil and gas industry

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Elisabeth; Wegrelius, Lena; Pettersson, Rachel [Outokumpu Stainless AB, Avesta (Sweden)

    2012-07-01

    The broad range of available stainless steel grades means that these materials can fulfil a wide variety of requirements within the oil and gas industry. The duplex grades have the advantage of higher strength than standard austenitic grades, while the superaustenitic grades provide a cost-effective alternative to nickel-base alloys in a number of cases. The paper presents the results of various types of laboratory testing to rank the grades in terms of resistance to pitting, crevice corrosion and stress corrosion cracking. Results from field testing in actual or simulated service conditions are discussed and a number of application examples, including process piping flexible, heat exchangers and topside equipment are presented. (author)

  18. Study of ultrasound waves attenuation: application to the nondestructive control of austenitic stainless steel welds

    International Nuclear Information System (INIS)

    Ultrasonic propagation simulation in anisotropic and heterogeneous media is essential for nondestructive testing by ultrasounds of multipass austenitic stainless steel welds that are specific of piping in nuclear power stations. Scattering at grain boundaries leads to a strong attenuation as a function of grain orientation. Attenuation measurement is complex. The implemented technique allows taking into account the physical reality of the beams and the material anisotropy. Ultrasonic propagation through the samples is modeled with transmission coefficients calculated with any incidence on a triclinic material. This method results in an increase of the attenuation versus grain orientation. For the first time, measured attenuation coefficients are integrated into a simulation code that validated them by comparison with experience. (author)

  19. Stochastic aspects of evolution of creep damage in austenitic stainless steel

    International Nuclear Information System (INIS)

    A stochastic model for the creep damage evolution and associated scatter in austenitic stainless steel has been developed in terms of a discontinuous Markov process. The magnitude of damage has been described in the form of a probability distribution function whose evolution in time characterizes the nondeterministic nature of the damage accumulation process. The long-term creep behavior on samples obtained from different locations of a thick walled SS304 LN steel pipe are studied under an identical stress and temperature condition so as to observe the scatter in creep deformation and failure data. Also the occurrences of damage and its accumulation due to creep deformation were evaluated through microstructural assessment using light optical microscope and scanning electron microscope. The validity of the model has been established by repeat data of SS304 LN steel and 316 stainless steel .

  20. The microstructural, mechanical, and fracture properties of austenitic stainless steel alloyed with gallium

    Science.gov (United States)

    Kolman, D. G.; Bingert, J. F.; Field, R. D.

    2004-11-01

    The mechanical and fracture properties of austenitic stainless steels (SSs) alloyed with gallium require assessment in order to determine the likelihood of premature storage-container failure following Ga uptake. AISI 304 L SS was cast with 1, 3, 6, 9, and 12 wt pct Ga. Increased Ga concentration promoted duplex microstructure formation with the ferritic phase having a nearly identical composition to the austenitic phase. Room-temperature tests indicated that small additions of Ga (less than 3 wt pct) were beneficial to the mechanical behavior of 304 L SS but that 12 wt pct Ga resulted in a 95 pct loss in ductility. Small additions of Ga are beneficial to the cracking resistance of stainless steel. Elastic-plastic fracture mechanics analysis indicated that 3 wt pct Ga alloys showed the greatest resistance to crack initiation and propagation as measured by fatigue crack growth rate, fracture toughness, and tearing modulus. The 12 wt pct Ga alloys were least resistant to crack initiation and propagation and these alloys primarily failed by transgranular cleavage. It is hypothesized that Ga metal embrittlement is partially responsible for increased embrittlement.

  1. Mechanism and estimation of fatigue crack initiation in austenitic stainless steels in LWR environments.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Energy Technology

    2002-08-01

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figures I-9.1 through I-9.6 of Appendix I to Section III of the Code specify fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of fatigue crack initiation in austenitic stainless steels in LWR coolant environments. The existing fatigue {var_epsilon}-N data have been evaluated to establish the effects of key material, loading, and environmental parameters (such as steel type, strain range, strain rate, temperature, dissolved-oxygen level in water, and flow rate) on the fatigue lives of these steels. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for austenitic stainless steels as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are presented. The influence of reactor environments on the mechanism of fatigue crack initiation in these steels is also discussed.

  2. Ultrasonic Examination of AN Austenitic Weld: Illustration of the Disturbances of the Ultrasonic Beam

    Science.gov (United States)

    Chassignole, B.; Dupond, O.; Doudet, L.; Duwig, V.; Etchegaray, N.

    2009-03-01

    The ultrasonic examination of the primary coolant piping of Pressurized Water Reactors (PWR) is an important challenge for the nuclear industry. Numerous studies were undertaken by EDF R&D for a few years to improve the NDT process on these applications and to help to their qualification. More particularly, a great deal was made on the examination of the austenitic stainless steel welds. Indeed, the anisotropic, heterogeneous and coarse granular structures of these welds lead to important disturbances of the ultrasonic propagation. This paper presents some examples of the experimental and numerical studies which allowed to highlight the different disturbances (beam deviation, division and attenuation). We pay more attention on spurious echoes which may appear when a plane defect is located in an austenitic weld. The experimental approach is based on tests on mock-ups containing artificial defects. On the other hand, a numerical approach with the finite element code ATHENA, developed by EDF, allows to explain the origin of the disturbances. We show the interest of this tool to carry out a close analysis of the ultrasonic mode conversions in the complex structure of the weld which produce the spurious echoes. Finally, the influence of the ultrasonic disturbances on performances in term of detection of the defects is discussed.

  3. Strip casting of stainless steels

    OpenAIRE

    Raabe, D.

    1997-01-01

    FLAT PRODUCTS OF STAINLESS STEELS ARE CONVENTIONALLY MANUFACTURED BY CONTINUOUS CASTING, HOT ROLLING, HOT BAND ANNEALING, PICKLING, COLD ROLLING AND RECRYSTALLISATION. IN THE LAST YEARS STRIP CASTING HAS INCREASINGLY ATTRACTED ATTENTION. IT OFFERS THREE IMPROVEMENTS IN COMPARISON TO THE CONVENTIONAL METHOD.1.) IT ALLOWS TO CAST STEEL SHEETS WITH THE SAME THICKNESS AND WIDTH AS THOSE PRODUCED BY HOT ROLLING. THIS MEANS THAT THE HOT ROLLING PROCESSIS BYPASSED. 2.) THE STRIP CAST STEEL REVEALS A...

  4. Scheduled Caste Women: Problems And Challenges

    OpenAIRE

    Vijayakumar Murthy; Jaikishan Thakur

    2013-01-01

    The paper analyzed the Caste system based on Varnas during the ancient India. It also examined the demerits of caste attached to the present scheduled castes in general and scheduled caste women in particular. The scheduled caste women are disadvantaged by their caste and gender and as such they are subject to exploitation and discrimination by their family members, by their caste people and by forward castes. Hence, there is increase in exploitation, discrimination and violence against the s...

  5. Microstructure and properties of Ti–Nb–V–Mo-alloyed high chromium cast iron

    Indian Academy of Sciences (India)

    Youping Ma; Xiulan Li; Yugao Liu; Shuyi Zhou; Xiaoming Dang

    2013-10-01

    The correlations of microstructure, hardness and fracture toughness of high chromium cast iron with the addition of alloys (titanium, vanadium, niobium and molybdenum) were investigated. The results indicated that the as-cast microstructure changed from hypereutectic, eutectic to hypoeutectic with the increase of alloy contents. Mo dissolved in austenite and increased the hardness by solid solution strengthening. TiC and NbC mainly existed in austenite and impeded the austenite dendrite development. V existed in multicomponent systems in forms of V alloy compounds (VCrFe8 and VCr2C2).With the increase of alloy additions, carbides size changed gradually from refinement to coarseness, hardness and impact toughness were increased and then decreased. Compared with the fracture toughness (6 J/cm2) and hardness (50.8HRC) without any alloy addition, the toughness and hardness at 0.60 V–0.60Ti–0.60Nb–0.35Mo (wt%) additions were improved and achieved to 11 J/cm2 and 58.9HRC, respectively. The synergistic roles of Ti, Nb, V and Mo influenced the solidification behaviour of alloy. The refinement of microstructure and improvement of carbides morphologies, size and distribution improved the impact toughness.

  6. Effect of austempering parameters on microstructure and mechanical properties of horizontal continuous casting ductile iron dense bars

    OpenAIRE

    Chun-jie Xu; Pan Dai; Zheng-yang Zhang

    2015-01-01

    In the present research, the orthogonal experiment was carried out to investigate the influence of different austempering process parameters (i.e. austenitizing temperature and time, and austempering temperature and time) on microstructure and mechanical properties of LZQT500-7 ductile iron dense bars with 172 mm in diameter which were produced by horizontal continuous casting (HCC). The results show that the major factors influencing the hardness of austempered ductile iron (ADI) are austeni...

  7. Transmission electron microscope studies of the chromium cast iron modified at use of B4C addition

    Directory of Open Access Journals (Sweden)

    K. Labisz

    2010-10-01

    Full Text Available Results of studies of the high alloy chromium cast iron with boron addition in form of the B4C phase powder are presented in this paper.The main field of interest is the identification of phases based on the transmission electron microscope study, occurred in this alloy aftersolidification process. The structure mainly consists of the austenite matrix and M7C3 carbide identified as the Cr7C3 phase.

  8. Machinability of Austempered Ductile Iron (ADI) Produced by Integrated Green Technology of Continuous Casting-Heat Treatment Processes

    Science.gov (United States)

    Meena, A.; El Mansori, M.; Ghidossi, P.

    2011-01-01

    This study presents the novel processing technique known as continuous casting-heat treatment processes to produce Austempered Ductile Iron (ADI) which is a new class of ductile iron. ADI is characterized by improved mechanical properties but has low machinability as compared to other cast irons and steel of similar strength. The novel technique is developed by the integration of casting (in die casting) and heat treatment processes in foundry to save cost energy and time. Specimens just after casting were austenitized at 930° C for 90 min and then austempered in fluidized bed at 380° C for 90 and 120 min. Hence, the effect of austempering time on the morphology of retained austenite and mechanical properties of the material were examined and compared with conventionally produced ADI. Drilling tests were then carried out to evaluate the machinability of ADI in terms of cutting forces, chip micro-hardness, chip morphology and surface roughness. The mechanical properties of ADI austempered for 120 min have found to be better as compare to the ADI austempered for 90 min.

  9. Use of an IGSCC damage index for cost benefit evaluation of BWR pipe cracking remedies

    International Nuclear Information System (INIS)

    A number of alternative approaches for eliminating or significantly reducing intergranular stress corrosion cracking (IGSCC) in BWR austenitic stainless steel piping have been developed. These include alternate materials, modified environments, and remedies which reduce steady state stresses. The cost and potential benefits of various remedies along with the implications of making no changes to the piping or plant chemistry are essential for making remedy implementation decisions and contingency planning. Unfortunately, the potential for IGSCC cracking with and without implementation of remedies depends on a large number of factors. For the current plant condition these include the original piping material and material condition, weld joint stresses, length of service and startup cycles and primary water chemistry history. In this paper, a damage index based on an engineering model for predicting the initiation of IGSCC in sensitized austenitic materials is used to quantify the likelihood of cracking with and without pipe cracking remedies as a function of time. This model is based on a fundamental understanding of IGSCC and explicitly accounts for material, material condition, environment, stress, cycles, time and cyclic wave shapes. Combination of these estimates with cost estimates for remedies and repairs provides a cost-benefit comparison of alternatives to a BWR plant owner

  10. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Ph.D Liu Jincheng

    2010-01-01

    @@ Note: This book consists of five sections: Chapter 1 Introduction, Chapter 2 Grey Iron, Chapter 3 Spheroidal Graphite Cast Iron, Chapter 4 Vermicular Cast Iron, and Chapter 5 White Cast Iron. CHINA FOUNDRY publishes this book in several parts serially, starting from the first issue of 2009.

  11. HYDROMODELLING OF CASTING PROCESSES

    Directory of Open Access Journals (Sweden)

    E. I. Marukovich

    2016-02-01

    Full Text Available The description of equipment for hydrodynamic experiments and methods of hydromodeling of foundry processes, allowing to carry out three-dimensional modeling of filling process, is given. This method can be used for identification of numerical models and development of casting technology of the new types of production.

  12. Extrusion cast explosive

    Science.gov (United States)

    Scribner, Kenneth J.

    1985-01-01

    Improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst are disclosed. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants.

  13. Thermal analysis of ductile iron in thin walled casting

    Directory of Open Access Journals (Sweden)

    M. Górny

    2007-12-01

    Full Text Available Hypereutectic ductile iron was cast in self hardening moulding sand to produce castings with the shape of Archimedes spirals and with wall thickness of 1, 2 and 3 mm. Inmould technique was used to produce thin wall ductile iron (TWDI. In this work it has been carried out thermal analysis in spiral with 3 mm wall thickness. The present work provides results of thermal analysis, that are initial temperature of metal in mould cavity, velocity of metal stream as well as solidification time. Measurement of temperature shows that there is essential its drop during filling of mould cavity and amounts 230 oC for distance 700 mm from the beginning of spiral. On the basic on first derivative of temperature versus time characteristic solidification points were distinguish, namely solidification of primary graphite, austenite dendrite and eutectic. Experimental measurements of temperature drop during filling of mould cavity along with microscopic examinations of castings structure can be used to verify computer modeling and simulation of fluid flow and thermal field in TWDI.

  14. Dry Flowing Abrasive Decontamination Technique for Pipe Systems with Swirling Air Flow

    International Nuclear Information System (INIS)

    A dry abrasive decontamination method was developed for removing radioactive corrosion products from surfaces of coolant pipe systems in decommissioning of a nuclear power plant. Erosion behavior of inside surfaces of stainless and carbon steel pipes by a swirling air flow containing alumina or cast-iron grit abrasive was studied. Erosion depths of the test pipes were approximately proportional to an abrasive concentration in air and an exponent of flow rate of airstream. The experimental results indicated that the present method could keep satisfactory erosion ability of abrasives even for a large-size pipe. The present method was successfully applied to 60Co-contaminated specimens sampled from a pipe of the water cleanup system of the Japan Power Demonstration Reactor

  15. Miniature pipe crawler tractor

    International Nuclear Information System (INIS)

    A pipe crawler tractor may comprise a half tractor assembly having a first base drive wheel, a second base drive wheel, and a top drive wheel. The drive wheels are mounted in spaced-apart relation so that the top drive wheel is positioned between the first and second base drive wheels. The mounting arrangement is also such that the first and second base drive wheels contact the inside surface of the pipe at respective first and second positions and so that the top drive wheel contacts the inside surface of the pipe at a third position, the third position being substantially diametrically opposed to the first and second positions. A control system connected to the half tractor assembly controls the rotation of the first base wheel, the second base wheel, and the top drive wheel to move the half tractor assembly within the pipe

  16. Miniature pipe crawler tractor

    Science.gov (United States)

    McKay, Mark D.; Anderson, Matthew O.; Ferrante, Todd A.; Willis, W. David

    2000-01-01

    A pipe crawler tractor may comprise a half tractor assembly having a first base drive wheel, a second base drive wheel, and a top drive wheel. The drive wheels are mounted in spaced-apart relation so that the top drive wheel is positioned between the first and second base drive wheels. The mounting arrangement is also such that the first and second base drive wheels contact the inside surface of the pipe at respective first and second positions and so that the top drive wheel contacts the inside surface of the pipe at a third position, the third position being substantially diametrically opposed to the first and second positions. A control system connected to the half tractor assembly controls the rotation of the first base wheel, the second base wheel, and the top drive wheel to move the half tractor assembly within the pipe.

  17. Heat Pipe Systems

    Science.gov (United States)

    1993-01-01

    The heat pipe was developed to alternately cool and heat without using energy or any moving parts. It enables non-rotating spacecraft to maintain a constant temperature when the surface exposed to the Sun is excessively hot and the non Sun-facing side is very cold. Several organizations, such as Tropic-Kool Engineering Corporation, joined NASA in a subsequent program to refine and commercialize the technology. Heat pipes have been installed in fast food restaurants in areas where humid conditions cause materials to deteriorate quickly. Moisture removal was increased by 30 percent in a Clearwater, FL Burger King after heat pipes were installed. Relative humidity and power consumption were also reduced significantly. Similar results were recorded by Taco Bell, which now specifies heat pipe systems in new restaurants in the Southeast.

  18. Evaluation of an improved centrifugal casting machine.

    Science.gov (United States)

    Donovan, T E; White, L E

    1985-05-01

    A Type III gold alloy, a silver-palladium alloy, and a base metal alloy were cast in two different centrifugal casting machines. With the number of complete cast mesh squares as an indicator of castability, the Airspin casting machine produced superior castings with all three alloys. The base metal alloy produced the greatest number of complete squares with both casting machines. PMID:3889295

  19. Silicon Heat Pipe Array

    Science.gov (United States)

    Yee, Karl Y.; Ganapathi, Gani B.; Sunada, Eric T.; Bae, Youngsam; Miller, Jennifer R.; Beinsford, Daniel F.

    2013-01-01

    Improved methods of heat dissipation are required for modern, high-power density electronic systems. As increased functionality is progressively compacted into decreasing volumes, this need will be exacerbated. High-performance chip power is predicted to increase monotonically and rapidly with time. Systems utilizing these chips are currently reliant upon decades of old cooling technology. Heat pipes offer a solution to this problem. Heat pipes are passive, self-contained, two-phase heat dissipation devices. Heat conducted into the device through a wick structure converts the working fluid into a vapor, which then releases the heat via condensation after being transported away from the heat source. Heat pipes have high thermal conductivities, are inexpensive, and have been utilized in previous space missions. However, the cylindrical geometry of commercial heat pipes is a poor fit to the planar geometries of microelectronic assemblies, the copper that commercial heat pipes are typically constructed of is a poor CTE (coefficient of thermal expansion) match to the semiconductor die utilized in these assemblies, and the functionality and reliability of heat pipes in general is strongly dependent on the orientation of the assembly with respect to the gravity vector. What is needed is a planar, semiconductor-based heat pipe array that can be used for cooling of generic MCM (multichip module) assemblies that can also function in all orientations. Such a structure would not only have applications in the cooling of space electronics, but would have commercial applications as well (e.g. cooling of microprocessors and high-power laser diodes). This technology is an improvement over existing heat pipe designs due to the finer porosity of the wick, which enhances capillary pumping pressure, resulting in greater effective thermal conductivity and performance in any orientation with respect to the gravity vector. In addition, it is constructed of silicon, and thus is better

  20. Lattice expansion of carbon-stabilized expanded austenite

    DEFF Research Database (Denmark)

    Hummelshøj, Thomas Strabo; Christiansen, Thomas; Somers, Marcel A. J.

    2010-01-01

    The lattice parameter of expanded austenite was determined as a function of the content of interstitially dissolved carbon in homogeneous, carburized thin stainless steel foils. For the first time this expansion of the face-centered cubic lattice is determined on unstrained austenite. It is found...

  1. Flow lines and microscopic elemental inhomogeneities in austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Mosley, Jr, W C

    1982-01-01

    Flow lines in mechanically formed austenitic stainless steels are known to influence fracture behavior. Enhancement of flow lines by chemical etching is evidence of elemental inhomogeneity. This paper presents the results of electron microprobe analyses to determine the nature of flow lines in three austenitic stainless steels: 21Cr-6Ni-9Mn, 304L, and 19Ni-18Cr.

  2. X-ray fractography studies on austenitic stainless steels

    NARCIS (Netherlands)

    Rajanna, K.; Pathiraj, B.; Kolster, B.H.

    1996-01-01

    In this investigation, the fracture surfaces of SS 304 and SS 316 austenitic steels were analysed using the X-ray fractography technique. In both cases, a decrease in the austenite content was observed at the fracture surface as a result of deformation induced martensite, indicating a linear relatio

  3. Investigation of joining techniques for advanced austenitic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lundin, C.D.; Qiao, C.Y.P.; Kikuchi, Y.; Shi, C.; Gill, T.P.S.

    1991-05-01

    Modified Alloys 316 and 800H, designed for high temperature service, have been developed at Oak Ridge National Laboratory. Assessment of the weldability of the advanced austenitic alloys has been conducted at the University of Tennessee. Four aspects of weldability of the advanced austenitic alloys were included in the investigation.

  4. Electropolishing and chemical passivation of austenitic steel

    Directory of Open Access Journals (Sweden)

    A. Baron

    2008-12-01

    Full Text Available Purpose: The aim of the paper is investigations a dependence between the parameters of the electrochemical treatment of austenitic steel and their electrochemical behavior in Tyrod solution.Design/methodology/approach: Specimens (rode 30 mm × ø1 mm were to give in to the surface treatment – mechanically polishing, electrolytic polishing and passivation with various parameter. Electrochemical investigations concerning the corrosion resistance of austenitic steel samples were carried out by means of the potentiodynamic and electrochemical impedance spectroscopy method.Findings: The analysis of the obtained results leads to the conclusion that chemical passivation affects also the chemical composition of the passive layer of steel and changes its resistance to corrosion. Electrolytic polishing improves corrosion resistance, as can be proved by the shift of the value of the corrosion potential and break-down potential of the passive layer and the initiation of pittings.Research limitations/implications: The obtained results are the basis for the optimization of anodic passivation parameters of the austenitic steel as a metallic biomaterial. The future research should be focused on selected more suitable parameters of the electrochemical impedance spectroscopy test to better describe process on the solid/ liquid interface.Practical implications: In result of the presented investigations it has been found that the best corrosion resistance can be achieved thanks to the application of electrolytic polishing of the steel in a special bath and chemical passivation in nitric (V acid with an addition of chromic (VI acid temperature t = 60°C for one hour.Originality/value: The enormous demand for metal implants has given rise to a search for cheap materials with a good biotolerance and resistance to corrosion. Most commonly used are steel implants assigned to remain in the organism for some limited time only. It was compare two electrochemical methods

  5. Potential dependence of SCC growth of cast stainless steels and weld material in high-temperature water

    International Nuclear Information System (INIS)

    SCC growth rates measurements were performed in hydrogenated simulated PWR primary water and oxygenated water environments at 320°C to examine SCC growth behaviors of SCS14A cast stainless steels and 316L weld material using half-inch size compact tension specimens (1/2TCT). The effects of thermal ageing and cold-work on SCC growth were examined in high-temperature water in different corrosion potential environments. And the corrosion behaviors of ferrite (α) and austenite (γ) phases were also investigated after testing in both low- and high- potential water environments to consider the cause of the corrosion potential dependence on SCC growth. The following results were obtained. No significant SCC growth was observed on SCS14A cast stainless steels and 316L weld material in simulated PWR water even after 1 year exposure. No influence on SCC by thermal ageing and cold-working of specimens was recognized after exposure in this simulated PWR primary water. Significant SCC growth was observed in high-potential water and a clear corrosion potential dependence was observed on SCC growth of SCS14A cast stainless steels and 316L weld material. Clear potential dependence on corrosion of ferrite and austenite phases was observed: the ferrite phase corroded more slowly in low-potential water and the austenite phase corroded more significantly in simulated PWR primary water. The difference in corrosion seemed to affect the SCC growth mechanism in PWR primary water. (author)

  6. Bulk metallic glass tube casting

    International Nuclear Information System (INIS)

    Research highlights: → Tubular specimens of Zr55Cu30Al10Ni5 cast in custom arc-melting furnace. → Tilt casting supplemented by suction casting. → Bulk metallic glass formed only with optimized processing parameters. → Fully amorphous tubes with 1.8 mm wall thickness and 25 mm diameter. - Abstract: Tubular bulk metallic glass specimens were produced, using a custom-built combined arc-melting tilt-casting furnace. Zr55Cu30Al10Ni5 tubes with outer diameter of 25 mm and 0.8-3 mm wall thicknesses were cast, with both tilt and suction casting to ensure mold filling. Tilt casting was found to fill one side of the tube mold first, with the rest of the tube circumference filled subsequently by suction casting. Optimized casting parameters were required to fully fill the mold and ensure glass formation. Too small melt mass and too low arc power filled the mold only partially. However, too large melt mass and higher arc power which lead to the best mold filling also lead to partial crystallization. Variations in processing parameters were explored, until a glassy ring with 1.8 mm thickness was produced. Different sections of the as-cast ring were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and instrumented indentation to ensure amorphous microstructure. Atomic force microscopy (AFM) was used to compare the surface qualities of the first- and last-filled sections. These measurements confirmed the glassy structure of the cast ring, and that, the tilt cast tube section consistently showed better surface quality than the suction cast section. Optimized casting parameters are required to fully realize the potential of directly manufacturing complex shapes out of high-purity bulk metallic glasses by tilt casting.

  7. Grain growth in heat resisting austenitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Denisova, I.K.; Zakharov, V.N.; Karpova, N.M.; Farber, V.M.

    1985-01-01

    A study was made on kinetics of grain growth in steels of 37Kh12N8G8 type alloyed by V, Nb, Ti, Mo, W. It was concluded that the nature of carbide phase and kinetics of its dissolution in heat resisting austenitic steels dictate steel tendency to grain growth. At the same time decrease of diffusion mobility of atoms in steel matrix during its alloying by titanium aid tungsten results in sufficient decrease of the tendency to grain growth and variation in grain size.

  8. Embrittlement of austenitic stainless steel welds

    International Nuclear Information System (INIS)

    To prevent hot-cracking, austenitic stainless steel welds generally contain a small percent of delta ferrite. Although ferrite has been found to effectively prevent hot-cracking, it can lead to embrittlement of welds when exposed to elevated temperatures. The aging behavior of type-308 stainless steel weld has been examined over a range of temperatures 475--850 C for times up to 10,000 hrs. Upon aging, and depending on the temperature range, the unstable ferrite may undergo a variety of solid state transformations. These phase changes creep-rupture and Charpy impact properties

  9. Tribocorrosion wear of austenitic and martensitic steels

    Directory of Open Access Journals (Sweden)

    G. Rozing

    2016-07-01

    Full Text Available This paper explores the impact of tribocorrosion wear caused by an aggressive acidic media. Tests were conducted on samples made of stainless steel AISI 316L, 304L and 440C. Austenitic steels were tested in their nitrided state and martensitic in quenched and tempered and then induction hardened state. Electrochemical corrosion resistance testing and analysis of the microstructure and hardness in the cross section was carried out on samples of selected steels. To test the possibility of applying surface modification of selected materials in conditions of use, tests were conducted on samples/parts in a worm press for final pressing.

  10. Wear behavior of austenite containing plate steels

    Science.gov (United States)

    Hensley, Christina E.

    As a follow up to Wolfram's Master of Science thesis, samples from the prior work were further investigated. Samples from four steel alloys were selected for investigation, namely AR400F, 9260, Hadfield, and 301 Stainless steels. AR400F is martensitic while the Hadfield and 301 stainless steels are austenitic. The 9260 exhibited a variety of hardness levels and retained austenite contents, achieved by heat treatments, including quench and tempering (Q&T) and quench and partitioning (Q&P). Samples worn by three wear tests, namely Dry Sand/Rubber Wheel (DSRW), impeller tumbler impact abrasion, and Bond abrasion, were examined by optical profilometry. The wear behaviors observed in topography maps were compared to the same in scanning electron microscopy micrographs and both were used to characterize the wear surfaces. Optical profilometry showed that the scratching abrasion present on the wear surface transitioned to gouging abrasion as impact conditions increased (i.e. from DSRW to impeller to Bond abrasion). Optical profilometry roughness measurements were also compared to sample hardness as well as normalized volume loss (NVL) results for each of the three wear tests. The steels displayed a relationship between roughness measurements and observed wear rates for all three categories of wear testing. Nanoindentation was used to investigate local hardness changes adjacent to the wear surface. DSRW samples generally did not exhibit significant work hardening. The austenitic materials exhibited significant hardening under the high impact conditions of the Bond abrasion wear test. Hardening in the Q&P materials was less pronounced. The Q&T microstructures also demonstrated some hardening. Scratch testing was performed on samples at three different loads, as a more systematic approach to determining the scratching abrasion behavior. Wear rates and scratch hardness were calculated from scratch testing results. Certain similarities between wear behavior in scratch testing

  11. Verification of ultrasonic indications in austenitic overlay

    International Nuclear Information System (INIS)

    An austenitic overlay on steel 15Kh2MFA was tested by an ultrasonic probe. Overlays of this kind are used in nuclear reactor pressure vessels. The results of the ultrasonic method were compared with those of the metallographic method. Metallographic analysis showed that the majority of defects found by ultrasonic tests included clusters of cavities, welded-in slag and cracks, which mostly occurred between the weld beads. The experiments gave evidence that defects not smaller than 0.5 mm in size can be well detected at depths not exceeding 7 mm. (M.D.). 3 figs

  12. Mossbauer and XRD characterization of the phase transformations in a Fe-Mn-Al-C-Mo-Si-Cu as cast alloy during tribology test

    International Nuclear Information System (INIS)

    In present study Fe-29.0Mn-6Al–0.9C-1.8Mo-1.6Si-0.4Cu (%w) alloy was obtained after melted in an induction furnace, and then molded as an ingot. From the as cast ingot it were cut samples for the different characterization measurements. The microstructure of the as-cast sample is of dendritic type and its XRD pattern was refined with the lines of the austenite, with a big volumetric fraction, and the lines of the martensite, with small volumetric fraction. The Mössbauer spectrum of the sample was fitted with a broad singlet which corresponds to disordered austenite. After the tribology test, its XRD pattern was refined with the lines of two austenite phases, one similar to the previous one and other with bigger lattice parameter. The total volumetric fraction of the austenite is smaller than that obtained for sample without wear. It was added the lines of the martensite phase with bigger volumetric fraction than that of the previous sample. The Mössbauer spectrum of the weared sample was fitted with two paramagnetic sites which correspond to the two Fe austenite phases and a hyperfine magnetic field distribution which is associated to the disordered original martensite and the new one which appears in the surface as a consequence of the wear process. These results show that during wear process the original austenite phase is transformed in martensite and in a new austenite phase. The increases of the martensitic phase improves mechanical properties and wear behavior

  13. Mossbauer and XRD characterization of the phase transformations in a Fe-Mn-Al-C-Mo-Si-Cu as cast alloy during tribology test

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J. [Universidad Autónoma de Occidente (Colombia); Piamba, J. F. [Universidad del Valle, Departamento Física (Colombia); Sánchez, H. [Universidad del Valle, Escuela de Materiales (Colombia); Alcazar, G. A. Pérez, E-mail: gpgeperez@gmail.com [Universidad del Valle, Departamento Física (Colombia)

    2015-06-15

    In present study Fe-29.0Mn-6Al–0.9C-1.8Mo-1.6Si-0.4Cu (%w) alloy was obtained after melted in an induction furnace, and then molded as an ingot. From the as cast ingot it were cut samples for the different characterization measurements. The microstructure of the as-cast sample is of dendritic type and its XRD pattern was refined with the lines of the austenite, with a big volumetric fraction, and the lines of the martensite, with small volumetric fraction. The Mössbauer spectrum of the sample was fitted with a broad singlet which corresponds to disordered austenite. After the tribology test, its XRD pattern was refined with the lines of two austenite phases, one similar to the previous one and other with bigger lattice parameter. The total volumetric fraction of the austenite is smaller than that obtained for sample without wear. It was added the lines of the martensite phase with bigger volumetric fraction than that of the previous sample. The Mössbauer spectrum of the weared sample was fitted with two paramagnetic sites which correspond to the two Fe austenite phases and a hyperfine magnetic field distribution which is associated to the disordered original martensite and the new one which appears in the surface as a consequence of the wear process. These results show that during wear process the original austenite phase is transformed in martensite and in a new austenite phase. The increases of the martensitic phase improves mechanical properties and wear behavior.

  14. Austenite Recrystallization and Controlled Rolling of Low Carbon Steels

    Institute of Scientific and Technical Information of China (English)

    DU Lin-xiu; ZHANG Zhong-ping; SHE Guang-fu; LIU Xiang-hua; WANG Guo-dong

    2006-01-01

    The dynamic recrystallization and static recrystallization in a low carbon steel were investigated through single-pass and double-pass experiments. The results indicate that as the deformation temperature increases and the strain rate decreases, the shape of the stress-strain curve is changed from dynamic recovery shape to dynamic recrystallization shape. The austenite could not recrystallize within a few seconds after deformation at temperature below 900 ℃. According to the change in microstructure during deformation, the controlled rolling of low carbon steel can be divided into four stages: dynamic recrystallization, dynamic recovery, strain-induced ferrite transformation, and rolling in two-phase region. According to the microstructure after deformation, the controlled rolling of low carbon steel can be divided into five regions: non-recrystallized austenite, partly-recrystallized austenite, fully-recrystallized austenite, austenite to ferrite transformation, and dual phase.

  15. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2010-01-01

    @@ Chapter 3 Spheroidal Graphite Cast Iron(I) Spheroidal Graphite Cast Iron, SG iron in short, refers to the cast iron in which graphite precipitates as spheroidal shape during solidification of liquid iron. The graphite in common commercial cast iron can only be changed from flake to spheroidal shape by spheroidising treatment. Since spheroidal graphite reduces the cutting effect of stress concentration, the metal matrix strength of SG iron can be applied around 70%-90%, thus the mechanical property of SG iron is significantly superior to other cast irons;even the tensile strength of SG iron is higher than that carbon steel.

  16. Crack growth rate of PWR piping

    International Nuclear Information System (INIS)

    The Aquitaine 1 program, carried out jointly by FRAMATOME and the CEA is intended to improve knowledge about cracking mechanisms in AISI 316 L austenitic stainless steel under conditions similar to those of the PWR environment (irradiation excluded). Experiments of fatigue crack growth are performed on piping elements, scale 1/4 of primary pipings, by means of internal hydraulic cyclic pressure. Interpretation of results requires a knowledge of the stress intensity factor Ksub(I) at the front of the crack. Results of a series of calculations of Ksub(I) obtained by different methods for defects of finite and infinite length (three dimensional calculations) are given in the paper. The following have been used: calculations by finite elements, calculations by weight function. Notches are machined on the test pipes, which are subjected to internal hydraulic pressure cycles, under cold conditions, to initiate a crack at the tip of the notch. They are then cycled at a frequency of 4 cycles/hour on on water demineralised loop at a temperature of 2800C, the pressure varying at each cycle between approximately 160 bars and 3 bars. After each test, a specimen containing the defect is taken from the pipe for micrographic analysis. For the first test the length of the longitudinal external defect is assumed infinite. The number of cycles carried out is 5880 cycles. Two defects are machined in the tube for the second test. The number of cycles carried out is N = 440. The tests are performed under hot conditions (T = 2800C). For the third test two defects are analysed under cold and hot conditions. The number of cycles carried out for the external defect is 7000 when hot and 90000 when cold. The number of cycles for the internal defect is 1650 when hot and 68000 when cold. In order to interpret the results, the data da/dN are plotted on a diagram versus ΔK. Comparisons are made between these results and the curves from laboratory tests

  17. Evaluation of thermal aging effect on primary pipe material in nuclear power plant by micro hardness test method

    International Nuclear Information System (INIS)

    The investigation was carried out on the changes in mechanical properties of the primary pipe material Z3CN20.09M after 10000 h aging at 400℃ by using micro- Vickers and impact testing machine. The results show that the impact energy of testing material decreases. However, the micro-Vickers hardness of ferrite phase and austenite phase which constitute the testing material increase and keep constant, respectively. The intrinsic relations were analyzed between the micro-Vickers hardness and the impact energy to make an attempt to present the micro-Vickers hardness measurement as a method applicable to evaluating the thermal aging of the primary pipe material. (authors)

  18. Mechanical properties of phase constituents in selected grades of cast steel

    Directory of Open Access Journals (Sweden)

    M. Garbiak

    2011-07-01

    Full Text Available The nanoindentation measurements performed on three cast steels of 0.3C-30Ni-18Cr type with various content of niobium and titanium were carried out.Mechanical propertiesofthe main phaseconstituents of the alloys, such as austenite, MC and M23C6 type carbides, were determined and analysed. The values of hardness (H and Young modulus (E for the austenite matrix were similar within the tested alloys. Essential differences (H=12 ÷ 24 GPa; E = 250 ÷ 400 GPa were found between the carbide phases present in tested alloys. The nanoindentation measurement on small particles is affected by different effects. One of these effects was excluded using numerical simulation of impressing the phase constituent into the matrix during indentation. The values of H and E obtained from simulation were: 30/450 GPa for NbC; 50/580 GPa for TiC; and 19/320 GPa for Cr23C6 respectively

  19. Effects of Carbon Content and Solidification Rate on the Thermal Conductivity of Grey Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Daniel Holmgren; Attila Diószegi; Ingvar L.Svensson

    2008-01-01

    The thermal conductivity/diffusivity of pearlitic grey irons with various carbon contents was investi- gated by the laser flash method. The materials were cast in controlled thermal environments producing three dissimilar cooling rates. The cooling rates together with the carbon content largely influence the thermal conductivity of grey iron. Linear relationships exist between the thermal conductivity and the carbon content, the carbon equivalent, and the fraction of the former primary solidified austenite transformed into pearlite. The results show that the optimal thermal transport properties are obtained at medium cooling rates. Equa- tions are given for the thermal conductivity of pearlite, solidified as pre-eutectic austenite, and the eutectic of grey iron. The thermal conductivity of pearlitic grey iron is modelled at both room temperature and elevated temperatures with good accuracy.

  20. Effects of carbon content and solidification rate on thermal conductivity of grey cast iron

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The thermal conductivity or diffusivity of pearlitic grey irons with various carbon contents is investigated by the laser flash method. The materials are cast in controlled thermal environments and produced in three dissimilar cooling rates. The cooling rate together with the carbon content largely influence the thermal conductivity of grey iron. Linear relationships exist between the thermal conductivity and the carbon content, the carbon equivalent and the fraction of former primary solidified austenite transformed into pearlite. The work shows that optimal thermal transport properties are obtained at medium cooling rates. Equations describing the thermal conductivity of pearlite,solidified as pre-eutectic austenite, and the eutectic of grey iron are derived. The thermal conductivity of pearlitic grey iron is modeled at both room temperature and elevated temperature with good accuracy.