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Nitin Saini - One of the best experts on this subject based on the ideXlab platform.
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Dissolution of δ-ferrite and its effect on mechanical properties of P92 steel welds
Materials Science and Engineering: A, 2020Co-Authors: Nitin Saini, Manas Mohan Mahapatra, Rahul S. Mulik, Rangasayee Kannan, Nitin Kumar SharmaAbstract:Abstract This paper reports on the dissolution of δ-ferrite in the weld fusion zone using post-weld normalizing and tempering (PWNT) and its effect on mechanical properties. The autogenous gas tungsten arc welding (GTAW) was used to prepare double-sided welded joints of P92 steel. After welding, post-weld heat treatment (PWHT) at 760 °C for 2 h and post-weld normalizing at 1050 °C for 1 h followed by tempering at 760 °C for 2 h were performed. The morphology, composition, structure, and hardness of δ-ferrite are verified. The effect of PWHT and PWNT on mechanical properties is also observed. In as-welded and PWHT conditions, the retention of δ-ferrite was observed while the dissolution of δ-ferrite was confirmed after PWNT. In the PWNT condition, uniform microhardness across the welded joint, increased ductility, and increased Charpy Toughness of weld fusion zone (almost equal to as received material) were achieved. Dissolution kinetics of δ-ferrite is quantified using Thermo-Calc for Scheil's solidification calculation and DICTRA for calculating diffusion coefficients of Cr and W at 1050 °C in austenite.
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role of evolving microstructure on the mechanical behaviour of p92 steel welded joint in as welded and post weld heat treated state
Journal of Materials Processing Technology, 2019Co-Authors: Chandan Pandey, Pradeep Kumar, M M Mahapatra, J G Thakre, Nitin SainiAbstract:Abstract An autogenous gas tungsten arc welded P92 weld joint was subjected to two different post weld heat treatment (PWHT). One PWHT involved tempering of the as-welded sample at 760 °C for 2 h (referred to as PWDT) followed by natural air cooling. The other PWHT involved normalizing (re-austenitizing) the as-welded sample at 1040 °C for 40 min followed by PWDT (referred as PWNT). The cross-section of the as-welded sample exhibited a higher degree of microstructural heterogeneity. Both the PWDT and PWNT heat treatment procedures reduced the heterogeneity gradient along the weld cross section. The heat affected zone (HAZ) of the as-welded and PWDT samples showed Charpy Toughness values of 3 ± 4 J and 64 ± 6 J, respectively, which were lower than that of the base metal (72 ± 5 J). The PWNT treated sample exhibited a HAZ Charpy Toughness value of 83 ± 4 J which was higher than that of the base metal. The brittle mode of the fracture with river patterns was observed for the as-welded and PWDT treated sample while a ductile mode of fracture with fine and shallow dimples was observed for the PWNT condition. The PWNT treatment resulted in dissolution of the ferrite patches and formation of a uniform microstructure along the weld cross section. The PWNT treated samples exhibited the lowest yield strength to tensile strength ratio supporting the enhanced ductility as a result of this re-austenizing heat treatment. The as-welded and PWDT treated weld joints showed the presence of detrimental δ ferrite phase in the weld fusion zone and the coarse grained heat affected zone. The PWNT completely removed the δ ferrite patches from the microstructure whereas the PWDT treatment merely reduced the range of the hardness of the δ ferrite from 179 to 301 HV (as welded) to 204–228 HV.
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Microstructural Evolution and Mechanical Properties of CSEF/M P92 Steel Weldments Welded Using Different Filler Compositions
Metallurgical and Materials Transactions A, 2018Co-Authors: Nitin Saini, Manas Mohan Mahapatra, Rahul S. MulikAbstract:In the present investigation, P92 steel weld joints were prepared using a shielded metal arc welding (SMAW) process for two different fillers, E911 and P92. A comparative study was performed on the microstructural evolution, tensile strength, microhardness, and Charpy Toughness across the P92 steel weldments in the as-welded and post-weld heat-treated (PWHT) conditions. The PWHT was performed at 760 °C for 2 hours. To study the effect of the different filler metals and PWHT on the mechanical properties, longitudinal and transverse tensile tests were carried out at room temperature for a constant cross-head speed of 1 mm/min. In the longitudinal direction, the tensile strength of the P92 steel welds was measured as 958 ± 35 and 1359 ± 38 MPa for the E911 and P92 filler, respectively. In the as-welded condition, the transverse tensile specimens were fractured from the fine-grained heat-affected zone or inter-critical heat-affected zone (FGHAZ/ICHAZ) and, after PWHT, the fracture location was shifted to over-tempered base metal from the FGHAZ/ICHAZ. After the PWHT, the tempering reaction resulted in lowering of the hardness throughout the weldment. After PWHT, the Charpy Toughness of the weld fusion zone and heat-affected zone (HAZ) of the E911 filler weldments was measured as 66 ± 5 and 142 ± 8 J, respectively. The minimum required Charpy Toughness of 47 J (EN1557: 1997) was achieved after the PWHT for both E911 and P92 filler.
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Autogenous Tungsten Inert Gas and Gas Tungsten Arc With Filler Welding of Dissimilar P91 and P92 Steels
Journal of Pressure Vessel Technology, 2018Co-Authors: Chandan Pandey, Manas Mohan Mahapatra, Pradeep Kumar, Nitin SainiAbstract:Creep strength ferritic/martensitic modified 9Cr-1Mo-V-Nb (P91) steel also designated as ASTM A335 and P92 steel are used for piping, cladding, ducts, wrappers, and the pressure vessel in Gen IV nuclear reactors. In the present investigation, a comparative study of the effect of autogenous tungsten inert gas welding (A-TIG) with double pass and multipass gas tungsten arc (GTA) welding with filler on microstructure evolution in the weld fusion zone and the mechanical properties of P91 and P92 steel welded joints was carried out. The microstructure evolution was studied in as-welded and postweld heat treatment (PWHT) condition. The study also focused on the evolution of δ-ferrite patches and their influence on the tensile properties of welded joints. PWHT was carried out at 760 °C with durations from 2 to 6 h. To study the effect of δ-ferrite evolution on mechanical properties, Charpy Toughness, microhardness, and tensile tests were performed. The acceptable microstructure and mechanical properties were obtained after the 6 h of PWHT for A-TIG arc welding process while for GTA weld with filler wire, it was obtained after the 2 h of PWHT at 760 °C.
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Effect of welding process and PWHT on δ-ferrite evolution in dissimilar P91 and P92 steel joint
Materials Today: Proceedings, 2018Co-Authors: Chandan Pandey, Manas Mohan Mahapatra, Pradeep Kumar, Nitin Saini, Rahul S. Mulik, J G ThakreAbstract:Abstract Ferritic/martensitic 9Cr-1Mo-V-Nb (P91) and 9Cr-0.5Mo-1.8W-V-Nb (P92) steel are used for high temperature (600-650°C) operating components in nuclear and thermal power plants. The present research work deals with the dissimilar joining of P91 and P92 steel using autogenous tungsten inert gas (TIG) welding and multi-pass gas tungsten arc welding (GTAW) with filler. The evolution of δ-ferrite patches in weld fusion zone and heat affected zones (HAZs) were characterized in as-welded and post weld heat treatment (PWHT) condition. PWHT was carried out at 760 °C for 2 h and 6 h, for both autogenous-TIG and GTA weld joints. Charpy Toughness and microhardness tests were performed for autogenous-TIG welding and GTA welding process under as-welded and PWHT condition.
Harshad Kumar Dharamshi Hansraj Bhadeshia - One of the best experts on this subject based on the ideXlab platform.
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role of delamination and crystallography on anisotropy of Charpy Toughness in api x80 steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: Harshad Kumar Dharamshi Hansraj BhadeshiaAbstract:Abstract The orientation dependence of Charpy Toughness has been investigated in API-X80 linepipe steel. The occurrence of delamination and preferential alignment of {1 0 0} cleavage planes are found to contribute to the observed anisotropy in Charpy properties. Delamination is also related to the presence of banding in the hot-rolled alloy, and the additional plasticity it entails during the process of fracture leads to an effective increase in Toughness. As a consequence, the Toughness is worst when the Charpy specimen is machined at 45° to the rolling direction because the extent of delamination at that orientation is minimal. The rolling and transformation textures also lead to a greater propensity of {1 0 0} ferrite planes parallel to the fracture surface for the 45° orientation, leading to a further decrease in Toughness. Some revealing results are also reported for unconventional Charpy test orientations in which the notch is prepared parallel to the plate.
R.s. Vidyarthy - One of the best experts on this subject based on the ideXlab platform.
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Microstructure Evolution and Charpy Toughness Relationship of A-TIG Weld Fusion Zone for Varying Tempering Time
Transactions of the Indian Institute of Metals, 2018Co-Authors: R.s. Vidyarthy, D K DwivediAbstract:In the present research work, activating flux tungsten inert gas (A-TIG) weld joints of AISI 409 ferritic stainless steel was subjected to post weld heat treatment at 750 °C followed by the air cooling. To study the effect of tempering time on the microstructural and mechanical properties of the weld fusion zone, tempering time was varied from 2 to 10 h. The current study also demonstrated the comprehensive microstructure–mechanical property relationships using the collective techniques of optical and electron microscopy, electron dispersive X-ray analysis techniques, and X-ray diffraction analysis. The results indicated that the Charpy Toughness of the fusion zone improved after 2 and 4 h of tempering, but the further stretch in tempering time resulted in a drastic drop in Charpy Toughness. The shape of the sulphide inclusions was found to be an important factor in deciding the Charpy Toughness of the A-TIG weld fusion zone. Maximum impact energy of 116 ± 9 J was observed by the sample tempered for 4 h.
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study of microstructure and mechanical property relationships of a tig welded p91 316l dissimilar steel joint
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2017Co-Authors: R.s. Vidyarthy, Anup Kulkarni, D. K. DwivediAbstract:Abstract The current work enunciated the effect of activating flux tungsten inert gas (A-TIG) welding on the microstructural, mechanical and corrosion behaviour of the 316L stainless steel (SS) and P91 steel weldment. The current study also demonstrated the comprehensive structure–property relationships of dissimilar joint weldment using the collective techniques of optical macro and microscopy, electron microscopy, and Energy-dispersive X-ray spectroscopy (EDS) techniques. Microstructure study reveals the presence of delta ferrite, austenite and martensite in different zones of the weldment. The dissimilar steel weldment failed from the 316L side fusion boundary during the tensile testing. Maximum impact energy was absorbed by the 316L SS side heat affected zone (HAZ) while minimum by P91 steel side HAZ during the Charpy Toughness test. The potentiodynamic test result suggested that the P91 side fusion boundary had minimum corrosion and pitting potential in all the weldment.
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Influence of M-TIG and A-TIG Welding Process on Microstructure and Mechanical Behavior of 409 Ferritic Stainless Steel
Journal of Materials Engineering and Performance, 2017Co-Authors: R.s. Vidyarthy, D. K. Dwivedi, M. VasudevanAbstract:The current study investigates the effects of activating flux tungsten inert gas welding (A-TIG) and multipass tungsten inert gas welding (M-TIG) on the weld morphology, angular distortion, microstructures and mechanical properties when welding 8-mm-thick 409 ferritic stainless steel (FSS). SiO_2 was used as activating flux for A-TIG welding, while SUPERTIG ER309L was used as filler for M-TIG welding. Bead-on-plate weld trials were carried out to obtain the full penetration by using different combinations of flux coating density, welding speed and welding current. An optical microscope, field emission scanning microscope (FESEM), and x-ray diffractometer were used for the metallurgical characterizations. Vickers hardness, tensile test, Charpy Toughness test, and creep behavior test were carried out to evaluate the mechanical properties of the base and weld metals. Experimental results indicate that the A-TIG process can increase the joint penetration and tends to reduce the angular distortion of the 409 FSS weldment. The A-TIG welded joint also exhibited greater mechanical strength. However, a critically low Charpy Toughness was measured for the A-TIG weld fusion zone, which was later sufficiently improved after post weld heat treatment (PWHT). It was concluded that PWHT is mandatory for A-TIG welded 409 FSS.
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Study of microstructure and mechanical property relationships of A-TIG welded P91–316L dissimilar steel joint
Materials Science and Engineering A, 2017Co-Authors: R.s. Vidyarthy, D K DwivediAbstract:The current work enunciated the effect of activating flux tungsten inert gas (A-TIG) welding on the microstructural, mechanical and corrosion behaviour of the 316L stainless steel (SS) and P91 steel weldment. The current study also demonstrated the comprehensive structure–property relationships of dissimilar joint weldment using the collective techniques of optical macro and microscopy, electron microscopy, and Energy-dispersive X-ray spectroscopy (EDS) techniques. Microstructure study reveals the presence of delta ferrite, austenite and martensite in different zones of the weldment. The dissimilar steel weldment failed from the 316L side fusion boundary during the tensile testing. Maximum impact energy was absorbed by the 316L SS side heat affected zone (HAZ) while minimum by P91 steel side HAZ during the Charpy Toughness test. The potentiodynamic test result suggested that the P91 side fusion boundary had minimum corrosion and pitting potential in all the weldment.
Chandan Pandey - One of the best experts on this subject based on the ideXlab platform.
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Mechanical and Metallurgical Characterization of Dissimilar P92/SS304 L Welded Joints Under Varying Heat Treatment Regimes
Metallurgical and Materials Transactions A, 2020Co-Authors: Chandan PandeyAbstract:This work was performed to characterize the dissimilar austenitic grade SS304 L and martensitic grade creep strength of an enhanced P92 steel welded joint. The welded joint was prepared using the autogenous gas tungsten arc welding process. The welded joint was subjected to conventional heat treatment consisting of tempering at 760 °C for 2 hours, followed by air cooling and unconventional heat treatment (UHT) consisting of normalizing (1040 °C/40 min), further followed by air cooling and, finally, stabilized tempering at 760 °C for 2 hours. The heat-treated welded joint was subjected to the microstructural characterization and mechanical testing. The room temperature Charpy Toughness (CT) testing for both the weld fusion zone (WFZ) and heat-affected zone, tensile testing, and hardness testing were performed to characterize the dissimilar welded joint. Stabilized microstructure associated with improved mechanical properties were observed for UHT. The CT and tensile strength were optimum for the UHT.
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an assessment for mechanical and microstructure behavior of dissimilar material welded joint between nuclear grade martensitic p91 and austenitic ss304 l steel
Journal of Manufacturing Processes, 2019Co-Authors: Jayant Gopal Thakare, Chandan Pandey, M M Mahapatra, Rahul S. MulikAbstract:Abstract The microstructural evolution and mechanical properties of gas tungsten arc welded creep strength enhanced martensitic (CSEM) and austenitic stainless steel (SS) dissimilar welded joint is explored in the as welded (AW) and post weld heat treated (PWHT) conditions. The as received normalized and tempered P91 steel has been welded with SS304 L by preparing a conventional groove and employing a P91 GTAW filler wire. The welded plate is subjected to PWHT at 760 °C for 120 min followed by air cooling. The P91 steel in as received condition exhibited fully martensitic (tempered) structure with lathe morphology and prior austenite grain boundaries while SS304 L have austenitic structure with twins. The heterogeneity (as-welded condition) across the welded joint were produced in terms of microstructure and mechanical properties (hardness, Charpy Toughness and tensile strength). The variation in mechanical properties has been minimized after the PWHT. PWHT has observed a drastic influence on mechanical properties and microstructure of weld fusion zone and HAZ of P91 side however, remain unaffected for the SS304 L side HAZ. The strength of the welded joint have been measured 1016 ± 2.5 MPa and 906 ± 6.5 in as-welded and PWHT condition with joint efficiency of 140 % and 125 %, respectively.
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Softening mechanism of P91 steel weldments using heat treatments
Archives of Civil and Mechanical Engineering, 2019Co-Authors: Chandan Pandey, Manas Mohan Mahapatra, Pradeep Kumar, F. Daniel, B. AdhithanAbstract:The tungsten inert gas welded P91 steel welded joints were subjected to the two different type of heat treatments including the postweld direct tempering (PWDT) and re-austenitizing based tempering (PWNT) treatment. The microstructure of weld fusion and heat affected zone (HAZ) were characterized in different heat treatment conditions using optical microscope and scanning electron microscope. For as-welded joint, a great heterogeneity was observed in microstructure and mechanical properties across the weldments. The Charpy Toughness of the as-welded joint was measured much lower than the minimum recommended value of 47 J and it was measured 8 ± 5 J. The PWHTs have found a beneficial effect in decreasing the microstructure heterogeneity across the welded joint and improving the mechanical properties. The PWDT resulted in a drastic improvement in the Charpy impact Toughness of the welded joint and it was measured 59 ± 5 J which was higher than the minimum required value of 47 J but still inferior than the base metal. The δ ferrite still remained in overlap zone of the weld fusion zone. The PWNT treatment resulted in homogeneous microstructure and hardness variation across the welded joint in transverse direction and Charpy impact Toughness (149 ±6 J) exceeded than that achieved in base metal.
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role of evolving microstructure on the mechanical behaviour of p92 steel welded joint in as welded and post weld heat treated state
Journal of Materials Processing Technology, 2019Co-Authors: Chandan Pandey, Pradeep Kumar, M M Mahapatra, J G Thakre, Nitin SainiAbstract:Abstract An autogenous gas tungsten arc welded P92 weld joint was subjected to two different post weld heat treatment (PWHT). One PWHT involved tempering of the as-welded sample at 760 °C for 2 h (referred to as PWDT) followed by natural air cooling. The other PWHT involved normalizing (re-austenitizing) the as-welded sample at 1040 °C for 40 min followed by PWDT (referred as PWNT). The cross-section of the as-welded sample exhibited a higher degree of microstructural heterogeneity. Both the PWDT and PWNT heat treatment procedures reduced the heterogeneity gradient along the weld cross section. The heat affected zone (HAZ) of the as-welded and PWDT samples showed Charpy Toughness values of 3 ± 4 J and 64 ± 6 J, respectively, which were lower than that of the base metal (72 ± 5 J). The PWNT treated sample exhibited a HAZ Charpy Toughness value of 83 ± 4 J which was higher than that of the base metal. The brittle mode of the fracture with river patterns was observed for the as-welded and PWDT treated sample while a ductile mode of fracture with fine and shallow dimples was observed for the PWNT condition. The PWNT treatment resulted in dissolution of the ferrite patches and formation of a uniform microstructure along the weld cross section. The PWNT treated samples exhibited the lowest yield strength to tensile strength ratio supporting the enhanced ductility as a result of this re-austenizing heat treatment. The as-welded and PWDT treated weld joints showed the presence of detrimental δ ferrite phase in the weld fusion zone and the coarse grained heat affected zone. The PWNT completely removed the δ ferrite patches from the microstructure whereas the PWDT treatment merely reduced the range of the hardness of the δ ferrite from 179 to 301 HV (as welded) to 204–228 HV.
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Autogenous Tungsten Inert Gas and Gas Tungsten Arc With Filler Welding of Dissimilar P91 and P92 Steels
Journal of Pressure Vessel Technology, 2018Co-Authors: Chandan Pandey, Manas Mohan Mahapatra, Pradeep Kumar, Nitin SainiAbstract:Creep strength ferritic/martensitic modified 9Cr-1Mo-V-Nb (P91) steel also designated as ASTM A335 and P92 steel are used for piping, cladding, ducts, wrappers, and the pressure vessel in Gen IV nuclear reactors. In the present investigation, a comparative study of the effect of autogenous tungsten inert gas welding (A-TIG) with double pass and multipass gas tungsten arc (GTA) welding with filler on microstructure evolution in the weld fusion zone and the mechanical properties of P91 and P92 steel welded joints was carried out. The microstructure evolution was studied in as-welded and postweld heat treatment (PWHT) condition. The study also focused on the evolution of δ-ferrite patches and their influence on the tensile properties of welded joints. PWHT was carried out at 760 °C with durations from 2 to 6 h. To study the effect of δ-ferrite evolution on mechanical properties, Charpy Toughness, microhardness, and tensile tests were performed. The acceptable microstructure and mechanical properties were obtained after the 6 h of PWHT for A-TIG arc welding process while for GTA weld with filler wire, it was obtained after the 2 h of PWHT at 760 °C.
Manas Mohan Mahapatra - One of the best experts on this subject based on the ideXlab platform.
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Dissolution of δ-ferrite and its effect on mechanical properties of P92 steel welds
Materials Science and Engineering: A, 2020Co-Authors: Nitin Saini, Manas Mohan Mahapatra, Rahul S. Mulik, Rangasayee Kannan, Nitin Kumar SharmaAbstract:Abstract This paper reports on the dissolution of δ-ferrite in the weld fusion zone using post-weld normalizing and tempering (PWNT) and its effect on mechanical properties. The autogenous gas tungsten arc welding (GTAW) was used to prepare double-sided welded joints of P92 steel. After welding, post-weld heat treatment (PWHT) at 760 °C for 2 h and post-weld normalizing at 1050 °C for 1 h followed by tempering at 760 °C for 2 h were performed. The morphology, composition, structure, and hardness of δ-ferrite are verified. The effect of PWHT and PWNT on mechanical properties is also observed. In as-welded and PWHT conditions, the retention of δ-ferrite was observed while the dissolution of δ-ferrite was confirmed after PWNT. In the PWNT condition, uniform microhardness across the welded joint, increased ductility, and increased Charpy Toughness of weld fusion zone (almost equal to as received material) were achieved. Dissolution kinetics of δ-ferrite is quantified using Thermo-Calc for Scheil's solidification calculation and DICTRA for calculating diffusion coefficients of Cr and W at 1050 °C in austenite.
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Softening mechanism of P91 steel weldments using heat treatments
Archives of Civil and Mechanical Engineering, 2019Co-Authors: Chandan Pandey, Manas Mohan Mahapatra, Pradeep Kumar, F. Daniel, B. AdhithanAbstract:The tungsten inert gas welded P91 steel welded joints were subjected to the two different type of heat treatments including the postweld direct tempering (PWDT) and re-austenitizing based tempering (PWNT) treatment. The microstructure of weld fusion and heat affected zone (HAZ) were characterized in different heat treatment conditions using optical microscope and scanning electron microscope. For as-welded joint, a great heterogeneity was observed in microstructure and mechanical properties across the weldments. The Charpy Toughness of the as-welded joint was measured much lower than the minimum recommended value of 47 J and it was measured 8 ± 5 J. The PWHTs have found a beneficial effect in decreasing the microstructure heterogeneity across the welded joint and improving the mechanical properties. The PWDT resulted in a drastic improvement in the Charpy impact Toughness of the welded joint and it was measured 59 ± 5 J which was higher than the minimum required value of 47 J but still inferior than the base metal. The δ ferrite still remained in overlap zone of the weld fusion zone. The PWNT treatment resulted in homogeneous microstructure and hardness variation across the welded joint in transverse direction and Charpy impact Toughness (149 ±6 J) exceeded than that achieved in base metal.
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Microstructural Evolution and Mechanical Properties of CSEF/M P92 Steel Weldments Welded Using Different Filler Compositions
Metallurgical and Materials Transactions A, 2018Co-Authors: Nitin Saini, Manas Mohan Mahapatra, Rahul S. MulikAbstract:In the present investigation, P92 steel weld joints were prepared using a shielded metal arc welding (SMAW) process for two different fillers, E911 and P92. A comparative study was performed on the microstructural evolution, tensile strength, microhardness, and Charpy Toughness across the P92 steel weldments in the as-welded and post-weld heat-treated (PWHT) conditions. The PWHT was performed at 760 °C for 2 hours. To study the effect of the different filler metals and PWHT on the mechanical properties, longitudinal and transverse tensile tests were carried out at room temperature for a constant cross-head speed of 1 mm/min. In the longitudinal direction, the tensile strength of the P92 steel welds was measured as 958 ± 35 and 1359 ± 38 MPa for the E911 and P92 filler, respectively. In the as-welded condition, the transverse tensile specimens were fractured from the fine-grained heat-affected zone or inter-critical heat-affected zone (FGHAZ/ICHAZ) and, after PWHT, the fracture location was shifted to over-tempered base metal from the FGHAZ/ICHAZ. After the PWHT, the tempering reaction resulted in lowering of the hardness throughout the weldment. After PWHT, the Charpy Toughness of the weld fusion zone and heat-affected zone (HAZ) of the E911 filler weldments was measured as 66 ± 5 and 142 ± 8 J, respectively. The minimum required Charpy Toughness of 47 J (EN1557: 1997) was achieved after the PWHT for both E911 and P92 filler.
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Autogenous Tungsten Inert Gas and Gas Tungsten Arc With Filler Welding of Dissimilar P91 and P92 Steels
Journal of Pressure Vessel Technology, 2018Co-Authors: Chandan Pandey, Manas Mohan Mahapatra, Pradeep Kumar, Nitin SainiAbstract:Creep strength ferritic/martensitic modified 9Cr-1Mo-V-Nb (P91) steel also designated as ASTM A335 and P92 steel are used for piping, cladding, ducts, wrappers, and the pressure vessel in Gen IV nuclear reactors. In the present investigation, a comparative study of the effect of autogenous tungsten inert gas welding (A-TIG) with double pass and multipass gas tungsten arc (GTA) welding with filler on microstructure evolution in the weld fusion zone and the mechanical properties of P91 and P92 steel welded joints was carried out. The microstructure evolution was studied in as-welded and postweld heat treatment (PWHT) condition. The study also focused on the evolution of δ-ferrite patches and their influence on the tensile properties of welded joints. PWHT was carried out at 760 °C with durations from 2 to 6 h. To study the effect of δ-ferrite evolution on mechanical properties, Charpy Toughness, microhardness, and tensile tests were performed. The acceptable microstructure and mechanical properties were obtained after the 6 h of PWHT for A-TIG arc welding process while for GTA weld with filler wire, it was obtained after the 2 h of PWHT at 760 °C.
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Effect of welding process and PWHT on δ-ferrite evolution in dissimilar P91 and P92 steel joint
Materials Today: Proceedings, 2018Co-Authors: Chandan Pandey, Manas Mohan Mahapatra, Pradeep Kumar, Nitin Saini, Rahul S. Mulik, J G ThakreAbstract:Abstract Ferritic/martensitic 9Cr-1Mo-V-Nb (P91) and 9Cr-0.5Mo-1.8W-V-Nb (P92) steel are used for high temperature (600-650°C) operating components in nuclear and thermal power plants. The present research work deals with the dissimilar joining of P91 and P92 steel using autogenous tungsten inert gas (TIG) welding and multi-pass gas tungsten arc welding (GTAW) with filler. The evolution of δ-ferrite patches in weld fusion zone and heat affected zones (HAZs) were characterized in as-welded and post weld heat treatment (PWHT) condition. PWHT was carried out at 760 °C for 2 h and 6 h, for both autogenous-TIG and GTA weld joints. Charpy Toughness and microhardness tests were performed for autogenous-TIG welding and GTA welding process under as-welded and PWHT condition.