The Experts below are selected from a list of 393 Experts worldwide ranked by ideXlab platform
R Priestner - One of the best experts on this subject based on the ideXlab platform.
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effect of thermomechanical processing in the Intercritical Region on hardenability of austenite of a dual phase steel
Journal of Materials Engineering and Performance, 2001Co-Authors: M Sarwar, E Ahmad, R PriestnerAbstract:Steels slabs containing different percentages of C, Mn, and Cr were Intercritically heat treated and rolled at 780 and 790 °C; they were then quenched to produce dual-phase microstructure in order to study the martensitic hardenability of austenite present in them. It was found that rolling of the two-phase (α+γ) microstructure elongated austenite particles and also reduced the martensitic hardenability of austenite particles, probably because the rolling increased the α/γ interfacial area, thus promoting the formation of ferrite during cooling. The martensite particles obtained in the rolled material were also elongated or “fibered” in the rolling direction. It was observed that the thermomechanical processing of a two-phase (α+γ) mixture has the detrimental effect of increasing the quenching power needed to yield a specific amount of martensite.
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effect of rolling in the Intercritical Region on the tensile properties of dual phase steel
Journal of Materials Engineering and Performance, 1998Co-Authors: E Ahmad, R PriestnerAbstract:A steel containing 0.088 wt% C, 1.2 wt% Mn, and 0.78 wt% Cr was rolled at Intercritical temperature (790 °C) and quenched to produce dual-phase microstructure. Rolling caused anisotropic increase in tensile strength and little change in ductility. The results suggest that rolling increased strength by a combination of strengthening of the ferrite and an increase in the stress transferred to the martensite. Up to 20% rolling reduction strengthened the ferrite by work hardening, larger reductions then reduced the strength of ferrite, anisotropically, due to increased recovery. Subgrains in ferrite were observed after rolling in the Intercritical Region which can contribute to the ultimate strength of the rolled material.
E Ahmad - One of the best experts on this subject based on the ideXlab platform.
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thermomechanical processing in the Intercritical Region and tensile properties of dual phase steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009Co-Authors: E Ahmad, T Manzoor, N HussainAbstract:Thermomechanical process of 50% rolling reductions were applied at different Intercritical temperatures on a low alloy steel containing 0.09% C, followed by quenching in the iced brine solution. Fibrous (ferrite + martensite) microstructures with variable contents of martensite were obtained. Rolling caused an increase in tensile strength and ductility in the longitudinal than the transverse directions at all levels of martensite, expect 35% of martensite where ductility is little affected. Microvoids were found to nucleate and grow in the necks of tensile specimens by fracture of martensite and by decohesion of the martensite/ferrite interface. The changes in density of the microvoids with distance from the fracture surface defined the straining behavior of the steel with different volume fractions of martensite. The growth of microvoids appeared to be interrupted when a critical stress was reached at which the ferrite cleaved. The martensite fibers in longitudinal directions appeared to be positioned for receiving stresses from ferrite. The increased straining with tensile deformation promoted ductile dimpling on fracture surfaces which were determined by the extent of void growth and coalescence prior to interruption by cleavage.
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effect of thermomechanical processing in the Intercritical Region on hardenability of austenite of a dual phase steel
Journal of Materials Engineering and Performance, 2001Co-Authors: M Sarwar, E Ahmad, R PriestnerAbstract:Steels slabs containing different percentages of C, Mn, and Cr were Intercritically heat treated and rolled at 780 and 790 °C; they were then quenched to produce dual-phase microstructure in order to study the martensitic hardenability of austenite present in them. It was found that rolling of the two-phase (α+γ) microstructure elongated austenite particles and also reduced the martensitic hardenability of austenite particles, probably because the rolling increased the α/γ interfacial area, thus promoting the formation of ferrite during cooling. The martensite particles obtained in the rolled material were also elongated or “fibered” in the rolling direction. It was observed that the thermomechanical processing of a two-phase (α+γ) mixture has the detrimental effect of increasing the quenching power needed to yield a specific amount of martensite.
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effect of rolling in the Intercritical Region on the tensile properties of dual phase steel
Journal of Materials Engineering and Performance, 1998Co-Authors: E Ahmad, R PriestnerAbstract:A steel containing 0.088 wt% C, 1.2 wt% Mn, and 0.78 wt% Cr was rolled at Intercritical temperature (790 °C) and quenched to produce dual-phase microstructure. Rolling caused anisotropic increase in tensile strength and little change in ductility. The results suggest that rolling increased strength by a combination of strengthening of the ferrite and an increase in the stress transferred to the martensite. Up to 20% rolling reduction strengthened the ferrite by work hardening, larger reductions then reduced the strength of ferrite, anisotropically, due to increased recovery. Subgrains in ferrite were observed after rolling in the Intercritical Region which can contribute to the ultimate strength of the rolled material.
A Salinasrodriguez - One of the best experts on this subject based on the ideXlab platform.
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effect of annealing prior to cold rolling on magnetic and mechanical properties of low carbon non oriented electrical steels
Journal of Magnetism and Magnetic Materials, 2011Co-Authors: E J Gutierrezcastaneda, A SalinasrodriguezAbstract:Abstract The effects of annealing prior to cold rolling on the microstructure, magnetic and mechanical properties of low-C grain non-oriented (GNO) electrical steels have been investigated. The grain structure of hot-rolled electrical steel strips is modified by annealing at temperatures between 700 and 1050 °C. Annealing at temperatures less than the ferrite to austenite+ferrite transformation temperature on heating (Ac 1 ) causes a marginal effect on the grain size. However, annealing in the Intercritical Region at temperatures between Ac 1 and Ac 3 (the ferrite+austenite to austenite transformation temperature on heating) causes rapid decarburization and development of large columnar ferrite grains free of carbide particles. This microstructure leads, after cold rolling and a fast annealing treatment, to carbide free, large ferrite grain microstructures with magnetic and mechanical properties superior to those observed typically in the same steel in the industrially fully processed condition. These results are attributed to the increment in grain size and to the {1 0 0} fiber texture developed during the final annealing at temperatures up to 850 °C. Annealing at higher temperatures, T >Ac 3 , results in a strong {1 1 1} fiber texture and an increase of the quantity of second phase particles present in the microstructure, which lead to a negative effect on the final properties. The results suggest that annealing prior to cold rolling offers an attractive alternative processing route for the manufacture of fully processed low C GNO electrical steels strips.
Laha K. - One of the best experts on this subject based on the ideXlab platform.
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Effect of Tungsten on Mechanical Properties of Reduced Activation Ferritic-Martensitic Steel Subjected to Intercritical Heat Treatment
The Authors. Published by Elsevier Ltd., 2013Co-Authors: Sasmal C.s., Laha K., Jayakumar T., Chandravathi K.s., Nandagopal M., Selvi S. Panneer, Parameswaran P., Kumar E. RajendraAbstract:AbstractFusion welded joint of RAFM steel as in other ferritic steels possesses lower creep rupture strength than the base st el. The failure in the joint is associated with the soft Intercritical Region of heat affected zone, which is subjected to peak temperatures in between Ac1 and Ac3 during weld thermal cycle. In this investigation effort has been initiated to understand the effect of tungsten in softening the 9Cr-W RAFM steels on Intercritical temperature exposure. Metallographic investigations were carried out on the heat-treated steels by optical and transmission electron microscopes. The steels at all heat treated conditions had tempered martensitic structure. Refinement of prior austenitic grain of the steels was noticed on soaking in the Intercritical temperature range. The grain size of the steels increased with soaking at temperatures well above the Ac3 transformation temperature. TEM investigation revealed that the martensitic laths were decorated with M23C6 type of carbides and the presence of MX type of (Ta,V)C carbides inside the laths. Hardness, tensile and creep tests were carried on the steels to elucidate the effects of soaking at temperatures in and around Ac1 and Ac3 transformation temperatures. All the steels suffered reduction in mechanical strength after soaking at temperatures in the Intercritical temperature range. Different softening tendency of the RAFM steel having different tungsten content on Intercritical annealing has been explained based on the microstructural investigation
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Comprehensive microstructural characterization in modified 9Cr-1Mo ferritic steel by ultrasonic measurements
'Springer Science and Business Media LLC', 2002Co-Authors: Kumar Anish, Laha K., Jayakumar T., Bhanu Sankara Rao K., Baldev RajAbstract:Modified 9Cr-1Mo ferritic steel (T91/P91) has been subjected to a series of heat treatments consisting of soaking for 5 minutes at the selected temperatures, starting from the α-phase Region (1073 K) to the γ+δ-phase Region (1623 K), followed by oil quenching. Hardness measurements, microstructural features, and grain-size measurements by the linear-intercept method have been used for correlating them with the ultrasonic parameters. Ultrasonic velocity and attenuation measurements, and spectral analysis of the first backwall echo have been used for characterization of the microstructures obtained by various heat treatments. As the soaking temperature increased above Ac1, the ultrasonic velocity decreased because of the increase in the volume fraction of martensite in the structure. There were sharp changes in the ultrasonic velocities corresponding to the two critical temperatures, Ac1 and Ac3. Ultrasonic longitudinal- and shear-wave velocities were found to be useful in identifying the Ac1 and Ac3 temperatures and for the determination of hardness in the Intercritical Region. However, ultrasonic attenuation and spectral analysis of the first backwall echo were found to be useful to characterize the variation in the prior-austenitic grain size and formation of δ ferrite above the Ac4 temperature. The scattering coefficients have been experimentally determined for various microstructures and compared with the theoretically calculated value of the scattering coefficients for iron reported in literature
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An assessment of creep deformation and fracture behavior of 2.25Cr-1Mo\ud
The Minerals Metals & Materials Society, 2001Co-Authors: Laha K., K S Chandravathi, S L Mannan, Rao Kbs, Dh SastryAbstract:The evaluation of the creep deformation and fracture behavior of a 2.25Cr-1Mo steel base metal, a 2.25Cr-1Mo/2.25Cr-1Mo similar weld joint, and a 2.25Cr-1Mo/Alloy 800 dissimilar weld joint at 823 K over a stress range of 90 to WO MPa has been carried out. The specimens for creep testing were taken from single-V weld pads fabricated by a shielded metal arc-welding process using 2.25Cr-1Mo steel (for similar-joint) and INCONEL 182 (for dissimilar-joint) electrodes. The weld pads were subsequently given a postweld hear treatment (PWHT) of 973 K for I hour. The microstructure and microhardness of the weld joints were evaluated in the as-welded, postweld heat-treated, and creep-tested conditions. The heat-affected zone (HAZ) of similar weld joint consisted of bainite in the coarse-prior-austenitic-grain (CPAG) Region near the fusion line, followed by bainite in the fine-prior-austenitic-grain (FPAG) and Intercritical Regions merging with the unaffected base metal. In addition to the HAZ structures in the 2.25Cr-1Mo steel, the dissimilar weld joint displayed a definite INCONEL/2.25Cr-1Mo weld interface structure present either as a sharp line or as a diffuse Region. A hardness trough was observed in the Intercritical Region of the HAZ in both weld joints, while a maxima in hardness was seen at the weld interface of the dissimilar weld joint. Both weld joints exhibited significantly lower rupture lives compared to the 2.25Cr-1Mo base metal. The dissimilar weld joint exhibited poor rupture life compared to the similar weld joint, at applied stresses lower than 130 MPa. In both weld joints, the strain distribution across the specimen gage length during creep testing varied significantly. During creep testing, localization of deformation occurred in the Intercritical HAZ. In the similar weld joint, at all stress levels investigated, and in the dissimilar weld joint, at stresses greater than or equal to 150 MPa, the creep failure occulted in the Intercritical HAZ. The fracture occurred by transgranular mode with a large number of dimples. At stresses below 150 MPa, the failure in the dissimilar weld joint occurred in the CPAG HAZ near to the weld interface. The failure occurred by extensive intergranular creep cavity formation
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An assessment of creep deformation and fracture behavior of 2.25Cr-1Mo similar and dissimilar weld joints
The Minerals Metals & Materials Society, 2001Co-Authors: Laha K., K S Chandravathi, S L Mannan, Rao, Bhanu Sankara K, Dh SastryAbstract:The evaluation of the creep deformation and fracture behavior of a 2.25Cr-1Mo steel base metal, a 2.25Cr-1Mo/2.25Cr-1Mo similar weld joint, and a 2.25Cr-1Mo/Alloy 800 dissimilar weld joint at 823 K over a stress range of 90 to WO MPa has been carried out. The specimens for creep testing were taken from single-V weld pads fabricated by a shielded metal arc-welding process using 2.25Cr-1Mo steel (for similar-joint) and INCONEL 182 (for dissimilar-joint) electrodes. The weld pads were subsequently given a postweld hear treatment (PWHT) of 973 K for I hour. The microstructure and microhardness of the weld joints were evaluated in the as-welded, postweld heat-treated, and creep-tested conditions. The heat-affected zone (HAZ) of similar weld joint consisted of bainite in the coarse-prior-austenitic-grain (CPAG) Region near the fusion line, followed by bainite in the fine-prior-austenitic-grain (FPAG) and Intercritical Regions merging with the unaffected base metal. In addition to the HAZ structures in the 2.25Cr-1Mo steel, the dissimilar weld joint displayed a definite INCONEL/2.25Cr-1Mo weld interface structure present either as a sharp line or as a diffuse Region. A hardness trough was observed in the Intercritical Region of the HAZ in both weld joints, while a maxima in hardness was seen at the weld interface of the dissimilar weld joint. Both weld joints exhibited significantly lower rupture lives compared to the 2.25Cr-1Mo base metal. The dissimilar weld joint exhibited poor rupture life compared to the similar weld joint, at applied stresses lower than 130 MPa. In both weld joints, the strain distribution across the specimen gage length during creep testing varied significantly. During creep testing, localization of deformation occurred in the Intercritical HAZ. In the similar weld joint, at all stress levels investigated, and in the dissimilar weld joint, at stresses greater than or equal to 150 MPa, the creep failure occulted in the Intercritical HAZ. The fracture occurred by transgranular mode with a large number of dimples. At stresses below 150 MPa, the failure in the dissimilar weld joint occurred in the CPAG HAZ near to the weld interface. The failure occurred by extensive intergranular creep cavity formation
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An assessment of creep deformation and fracture behavior of 2.25Cr-1Mo similar and dissimilar weld joints
'Springer Science and Business Media LLC', 2001Co-Authors: Laha K., Bhanu Sankara Rao K., Chandravathi K. S., Mannan S. L., Sastry D. H.Abstract:The evaluation of the creep deformation and fracture behavior of a 2.25Cr-1Mo steel base metal, a 2.25Cr-1Mo/2.25Cr-1Mo similar weld joint, and a 2.25Cr-1Mo/Alloy 800 dissimilar weld joint at 823 K over a stress range of 90 to 250 MPa has been carried out. The specimens for creep testing were taken from single-V weld pads fabricated by a shielded metal arc-welding process using 2.25Cr-1Mo steel (for similar-joint) and INCONEL 182 (for dissimilar-joint) electrodes. The weld pads were subsequently given a postweld heat treatment (PWHT) of 973 K for 1 hour. The microstructure and microhardness of the weld joints were evaluated in the as-welded, postweld heat-treated, and creep-tested conditions. The heat-affected zone (HAZ) of similar weld joint consisted of bainite in the coarse-prior-austenitic-grain (CPAG) Region near the fusion line, followed by bainite in the fine-prior-austenitic-grain (FPAG) and Intercritical Regions merging with the unaffected base metal. In addition to the HAZ structures in the 2.25Cr-1Mo steel, the dissimilar weld joint displayed a definite INCONEL/2.25Cr-1Mo weld interface structure present either as a sharp line or as a diffuse Region. A hardness trough was observed in the Intercritical Region of the HAZ in both weld joints, while a maxima in hardness was seen at the weld interface of the dissimilar weld joint. Both weld joints exhibited significantly lower rupture lives compared to the 2.25Cr-1Mo base metal. The dissimilar weld joint exhibited poor rupture life compared to the similar weld joint, at applied stresses lower than 130 MPa. In both weld joints, the strain distribution across the specimen gage length during creep testing varied significantly. During creep testing, localization of deformation occurred in the Intercritical HAZ. In the similar weld joint, at all stress levels investigated, and in the dissimilar weld joint, at stresses ≥150 MPa, the creep failure occurred in the Intercritical HAZ. The fracture occurred by transgranular mode with a large number of dimples. At stresses below 150 MPa, the failure in the dissimilar weld joint occurred in the CPAG HAZ near to the weld interface. The failure occurred by extensive intergranular creep cavity formation
K S Chandravathi - One of the best experts on this subject based on the ideXlab platform.
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a comparison of creep rupture strength of ferritic austenitic dissimilar weld joints of different grades of cr mo ferritic steels
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2012Co-Authors: K Laha, K S Chandravathi, P Parameswaran, Sunil Goyal, M D MathewAbstract:Evaluations of creep rupture properties of dissimilar weld joints of 2.25Cr-1Mo, 9Cr-1Mo, and 9Cr-1MoVNb steels with Alloy 800 at 823 K were carried out. The joints were fabricated by a fusion welding process employing an INCONEL 182 weld electrode. All the joints displayed lower creep rupture strength than their respective ferritic steel base metals, and the strength reduction was greater in the 2.25Cr-1Mo steel joint and less in the 9Cr-1Mo steel joint. Failure location in the joints was found to shift from the ferritic steel base metal to the Intercritical Region of the heat-affected zone (HAZ) of the ferritic steel (type IV cracking) with the decrease in stress. At still lower stresses, the failure in the joints occurred at the ferritic/austenitic weld interface. The stress-life variation of the joints showed two-slope behavior and the slope change coincided with the occurrence of ferritic/austenitic weld interface cracking. Preferential creep cavitation in the soft Intercritical HAZ induced type IV failure, whereas creep cavitation at the interfacial particles induced ferritic/austenitic weld interface cracking. Micromechanisms of the type IV failure and the ferritic/austenitic interface cracking in the dissimilar weld joint of the ferritic steels and relative cracking susceptibility of the joints are discussed based on microstructural investigation, mechanical testing, and finite element analysis (FEA) of the stress state across the joint.
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type iv cracking susceptibility in weld joints of different grades of cr mo ferritic steel
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2009Co-Authors: K Laha, K S Chandravathi, P Parameswaran, Bhanu Sankara K RaoAbstract:Relative type-IV cracking susceptibility in 2.25Cr-1Mo, 9Cr-1Mo, and 9Cr-1MoVNb ferritic steel weld joint has been assessed. The type-IV cracking was manifested as preferential accumulation of creep deformation and cavitation in the relatively soft Intercritical Region of heat affected zone of the weld joint. The type-IV cracking susceptibility has been defined as the reduction in creep-rupture strength of weld joint compared to its base metal. The 2.25Cr-1Mo steel exhibited more susceptibility to type-IV cracking at relatively lower temperatures; whereas, at higher temperatures, 9Cr-1MoVNb steel was more susceptible. The relative susceptibility to type-IV cracking in the weld joint of the Cr-Mo steels has been rationalized on the basis of creep-strengthening mechanisms operating in the steels and their venerability to change on Intercritical heating during weld thermal cycle, subsequent postweld heat treatment, and creep exposure.
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characterization of microstructures across the heat affected zone of the modified 9cr 1mo weld joint to understand its role in promoting type iv cracking
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2007Co-Authors: K Laha, K S Chandravathi, P Parameswaran, Bhanu Sankara K Rao, S L MannanAbstract:In the postweld heat-treated (PWHT) fusion welded modified 9Cr-1Mo steel joint, a soft zone was identified at the outer edge of the heat-affected zone (HAZ) of the base metal adjacent to the deposited weld metal. Hardness and tensile tests were performed on the base metal subjected to soaking for 5 minutes at temperatures below Ac1 to above Ac3 and tempering at the PWHT condition. These tests indicated that the soft zone in the weld joint corresponds to the Intercritical Region of HAZ. Creep tests were conducted on the base metal and cross weld joint. At relatively lower stresses and higher test temperatures, the weld joint possessed lower creep rupture life than the base metal, and the difference in creep rupture life increased with the decrease in stress and increase in temperature. Preferential accumulation of creep deformation coupled with extensive creep cavitation in the Intercritical Region of HAZ led to the premature failure of the weld joint in the Intercritical Region of the HAZ, commonly known as type IV cracking. The microstructures across the HAZ of the weld joint have been characterized to understand the role of microstructure in promoting type IV cracking. Strength reduction in the Intercritical HAZ of the joint resulted from the combined effects of coarsening of dislocation substructures and precipitates. Constrained deformation of the soft Intercritical HAZ sandwich between relatively stronger constitutes of the joint induced creep cavitation in the soft zone resulting in premature failure.
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An assessment of creep deformation and fracture behavior of 2.25Cr-1Mo\ud
The Minerals Metals & Materials Society, 2001Co-Authors: Laha K., K S Chandravathi, S L Mannan, Rao Kbs, Dh SastryAbstract:The evaluation of the creep deformation and fracture behavior of a 2.25Cr-1Mo steel base metal, a 2.25Cr-1Mo/2.25Cr-1Mo similar weld joint, and a 2.25Cr-1Mo/Alloy 800 dissimilar weld joint at 823 K over a stress range of 90 to WO MPa has been carried out. The specimens for creep testing were taken from single-V weld pads fabricated by a shielded metal arc-welding process using 2.25Cr-1Mo steel (for similar-joint) and INCONEL 182 (for dissimilar-joint) electrodes. The weld pads were subsequently given a postweld hear treatment (PWHT) of 973 K for I hour. The microstructure and microhardness of the weld joints were evaluated in the as-welded, postweld heat-treated, and creep-tested conditions. The heat-affected zone (HAZ) of similar weld joint consisted of bainite in the coarse-prior-austenitic-grain (CPAG) Region near the fusion line, followed by bainite in the fine-prior-austenitic-grain (FPAG) and Intercritical Regions merging with the unaffected base metal. In addition to the HAZ structures in the 2.25Cr-1Mo steel, the dissimilar weld joint displayed a definite INCONEL/2.25Cr-1Mo weld interface structure present either as a sharp line or as a diffuse Region. A hardness trough was observed in the Intercritical Region of the HAZ in both weld joints, while a maxima in hardness was seen at the weld interface of the dissimilar weld joint. Both weld joints exhibited significantly lower rupture lives compared to the 2.25Cr-1Mo base metal. The dissimilar weld joint exhibited poor rupture life compared to the similar weld joint, at applied stresses lower than 130 MPa. In both weld joints, the strain distribution across the specimen gage length during creep testing varied significantly. During creep testing, localization of deformation occurred in the Intercritical HAZ. In the similar weld joint, at all stress levels investigated, and in the dissimilar weld joint, at stresses greater than or equal to 150 MPa, the creep failure occulted in the Intercritical HAZ. The fracture occurred by transgranular mode with a large number of dimples. At stresses below 150 MPa, the failure in the dissimilar weld joint occurred in the CPAG HAZ near to the weld interface. The failure occurred by extensive intergranular creep cavity formation
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An assessment of creep deformation and fracture behavior of 2.25Cr-1Mo similar and dissimilar weld joints
The Minerals Metals & Materials Society, 2001Co-Authors: Laha K., K S Chandravathi, S L Mannan, Rao, Bhanu Sankara K, Dh SastryAbstract:The evaluation of the creep deformation and fracture behavior of a 2.25Cr-1Mo steel base metal, a 2.25Cr-1Mo/2.25Cr-1Mo similar weld joint, and a 2.25Cr-1Mo/Alloy 800 dissimilar weld joint at 823 K over a stress range of 90 to WO MPa has been carried out. The specimens for creep testing were taken from single-V weld pads fabricated by a shielded metal arc-welding process using 2.25Cr-1Mo steel (for similar-joint) and INCONEL 182 (for dissimilar-joint) electrodes. The weld pads were subsequently given a postweld hear treatment (PWHT) of 973 K for I hour. The microstructure and microhardness of the weld joints were evaluated in the as-welded, postweld heat-treated, and creep-tested conditions. The heat-affected zone (HAZ) of similar weld joint consisted of bainite in the coarse-prior-austenitic-grain (CPAG) Region near the fusion line, followed by bainite in the fine-prior-austenitic-grain (FPAG) and Intercritical Regions merging with the unaffected base metal. In addition to the HAZ structures in the 2.25Cr-1Mo steel, the dissimilar weld joint displayed a definite INCONEL/2.25Cr-1Mo weld interface structure present either as a sharp line or as a diffuse Region. A hardness trough was observed in the Intercritical Region of the HAZ in both weld joints, while a maxima in hardness was seen at the weld interface of the dissimilar weld joint. Both weld joints exhibited significantly lower rupture lives compared to the 2.25Cr-1Mo base metal. The dissimilar weld joint exhibited poor rupture life compared to the similar weld joint, at applied stresses lower than 130 MPa. In both weld joints, the strain distribution across the specimen gage length during creep testing varied significantly. During creep testing, localization of deformation occurred in the Intercritical HAZ. In the similar weld joint, at all stress levels investigated, and in the dissimilar weld joint, at stresses greater than or equal to 150 MPa, the creep failure occulted in the Intercritical HAZ. The fracture occurred by transgranular mode with a large number of dimples. At stresses below 150 MPa, the failure in the dissimilar weld joint occurred in the CPAG HAZ near to the weld interface. The failure occurred by extensive intergranular creep cavity formation