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Item An assessment for mechanical and microstructure behavior of dissimilar material welded joint between nuclear grade martensitic P91 and austenitic SS304 L steel(2019) Thakare J.G.; Pandey C.; Mahapatra M.M.; Mulik R.S.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. � 2019 The Society of Manufacturing EngineersItem Fracture behaviour of crept P91 welded sample for different post weld heat treatments condition(2019) Pandey C.; Mahapatra M.M.; Kumar P.; Sirohi S.In the present research work, P91 steel plates of thickness 18 mm were welded using the shielded metal arc welding process. The welded steel plate subjected to different heat treatment condition including post weld heat treatment (760 �C for 2 h, followed by air cooling) and re-austenitizing (1040 �C for 60 min and air cooled) and tempered (760 �C for 2 h, followed by air cooling). The heat treatments were referred as the PWHT and PWNT. The creep sample was prepared to form the welded and heat treated plate. The creep tests were performed at 620 �C for stresses of 150 and 200 MPa. The weld fusion zone and fine-grained heat affected zone of the crept sample were characterized using the field emission scanning electron microscope (FESEM). The fracture surface morphology of crept sample was also studied using the FESEM. The maximum creep exposure time was measured for the PWNT sample as a result of homogeneous microstructure across the weldments. � 2018Item Investigation of the microstructure, mechanical and wear properties of AA6061-T6 friction stir weldments with different particulate reinforcements addition(2019) Abioye T.E.; Zuhailawati H.; Anasyida A.S.; Yahaya S.A.; Dhindaw B.K.Welding of heat-treated AA6061-T6 often results in mechanical and wear properties deterioration because of the dissolution of the strengthening precipitates at the joint. Enhancement of these properties has been accomplished for non-heat treatable aluminium alloys through the addition of reinforcement particles in the joint. However, its application to AA6061-T6 is scarce. In this work, the microstructure, hardness and wear resistance of AA6061-T6 friction stir welded joints reinforced with SiC, B4C and Al2O3 particles were investigated while the base metal and the unreinforced welded joint were utilised as the control. Aluminium matrix grains refinement which improved with increased particle distribution homogeneity occurred in the entire welded joints. All the reinforced welded joints showed improvements on the unreinforced joint in terms of hardness and wear resistance because of the particles high hardness and substantially increased grain refinement that occurred in the reinforced welded joints. Due to B4C extremely high hardness and homogeneous distribution in the joint, B4C reinforced joint exhibited the highest improvements in hardness (42%) and wear rate (67%) at low-load condition. However, at high-load condition, SiC followed by the Al2O3 reinforced joints showed the least wear rate even lower than the base metal. The matrix hardness significantly influenced the wear performance at low-load but the overall effects of the reinforcement particles were predominant at high-load condition. The reinforcements' additions reduced the wear rate of the welded joint by up to a factor of 1.7 and 1.9 at low and high load conditions respectively. � 2019 The Authors.Item Study on effect of double austenitization treatment on fracture morphology tensile tested nuclear grade P92 steel(2019) Pandey C.; Mahapatra M.M.; Kumar P.; Kumar P.; Saini N.; Thakare J.G.; Kumar S.Effect of �conventional normalizing and tempering� (CNT) and �double austenitization based normalizing and tempering� (DNT) process on microstructure characteristic and mechanical behavior was studied forP92 steel. In CNT heat treatment, P92 steel is normalized at 1040 �C/air cool and tempered with 760 �C/2 h/air cool. In DNT heat treatment, initially normalizing was performed at 1040 �C for 1 h followed by water quenching. After that sample was normalized in the temperature range of 950�1150 �C for 1 h and tempered at 760 �C/2 h/air cool (950 �C-DNT1, 1050 �C-DNT2, 1150 �C-DNT3).Grain size for CNT and DNT1 treatment were measured 17 � 7 ?m and 12 � 5 ?m. A DNT treatment resulted in homogeneous microstructure formation that led to improved mechanical properties as compared to CNT treatment. The DN based heat treatment produced complete martensitic microstructure formation by complete dissolution of carbide precipitates. The optimized room temperature condition was obtained for the DNT 1 heat treatment. � 2018 Elsevier LtdItem Influence of filler metals and PWHT regime on the microstructure and mechanical property relationships of CSEF steels dissimilar welded joints(2019) Saini N.; Mulik R.S.; Mahapatra M.M.The nuclear grade modified 9Cr�1Mo (P91) and 9Cr-0.5Mo-1.8W�V�Nb (P92) are commonly used material for power plant components operating in the temperature range of 600�650 �C. For such steels, the creep strength at the elevated operating temperature is the prime criteria. However, microstructure stability and notch toughness also play an important role, especially for the welded joints to meet the pressure test at room temperature. The room temperature mechanical properties of the welded joint are strongly influenced by the welding process, filler composition, composition of the base plate and heat treatment performed after the welding. In present work, P91 and P92 dissimilar multi-pass welded joints have been produced using the different filler rod. The microstructure of the welded joint has been studied for the different filler composition in various heat treatment condition. The room temperature Charpy impact toughness and tensile properties for the different welded joints (different filler) have been also studied and related with the microstructure of the welded joint. From the results, it has been concluded that a higher amount of ferrite stabilizer in P92 filler promotes the formation of the ? ferrite in the weld fusion zone. � 2019 Elsevier LtdItem Mechanical and Wear Behaviour of Hot-Pressed 304 stainless Steel Matrix Composites Containing TiB 2 Particles(2019) Sahoo S.; Jha B.B.; Mahata T.; Sharma J.; Murthy T.S.R.C.; Mandal A.In the present article, mechanical and wear behaviour of hot-pressed 304 stainless steel matrix composites containing 2 and 4�vol% TiB 2 particles was investigated. A density of over 92% was achieved at optimum hot-pressing temperature and TiB 2 particles� content. Microhardness and yield strength of the composites were found to be improved remarkably as compared to their unreinforced counterpart. The enhancement of mechanical properties of the composites was discussed in light of their microstructural aspects and different possible strengthening mechanism models. Taylor strengthening was found to be dominant strengthening mechanism as compared to Orowan strengthening and load-bearing effect. Dry sliding wear behaviour was also investigated under load of 35�N at sliding speed 0.3�m/s. The wear resistance of the composites was found to be improved owing to uniform distribution of hard TiB 2 particles. Based on our findings, it was concluded that processing parameters and amount of TiB 2 have significant influence on mechanical and wear behaviour of steel matrix composites. � 2019, The Indian Institute of Metals - IIM.Item Strength and durability characteristic of alkali activated GGBS stabilized red mud as geo-material(2019) Alam S.; Das S.K.; Rao B.H.Red mud (bauxite residue) is generated during the Bayer's process of aluminium production in the ratio of one part aluminium to 0.8�1.5 part red mud and is considered as an industrial waste. The storage of unutilised red mud creates a geoenvironmental problem due to its highly alkaline nature (pH > 11) as it contaminates the groundwater as well as surface water. The present paper discusses the strength and durability properties of the stabilized red mud using alkali (Na 2 SiO 3 ) activated ground granulated blast furnace slag (GGBS) and its microstructural property for possible application as a geo-material. One of the major problems associated with the geo-materials is the strength loss and weathering due to the exposure to adverse environment. So, the emphasis has been given to the durability of the stabilized red mud by keeping in mind its various uses in geotechnical construction. The durability studies are performed by considering the effect of wet-dry cycles on compressive strength. In addition, the results of slake durability test and impact strength index are also discussed. The microstructural and chemical investigations are performed using scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively, to correlate with the strength and durability characteristics. The chemistry of leachate in terms of heavy toxic metals (Hg, As, Pb, and Cr) as identified by EPA is also studied and it was found that the stabilized red mud is non-toxic. � 2019 Elsevier LtdItem Role of Heat Treatment on Grain Refinement and Microhardness of 9Cr�1Mo�V�Nb Steel(2019) Pandey C.; Sirohi S.; Mahapatra M.M.; Kumar P.; Bansal K.K.Effect of �double austenitizing� (DN) on microstructure evolution and mechanical properties of martensitic 9Cr�1Mo�V�Nb (P91) steel were studied and compared with the �conventional normalizing� (CN) process. In CN treatment, P91 steel is normalized at 1050��C for 1�h, finally air cooled. In DN treatment, the first stage of normalizing was performed at 1050��C/1�h/air cool. The second stage of normalizing was performed in the temperature range of 950�1150��C for 1�h (950��C-DN1, 1050��C-DN2, 1150��C-DN3), followed by water quenching. The grain size was measured 42 and 35��m for CN and DN1 treatment, respectively. The double normalizing (DN) produced complete martensitic microstructure as a result of complete dissolution of precipitates. In DN-based heat treatment, optimized microstructure and mechanical properties were obtained for the sample that normalized at 950��C, followed by water quenching. � 2019, ASM International.Item Characterization of weld fusion zone for TIG welded p91 and P92 steels(2018) Pandey C.; Mohan Mahapatra M.; Kumar P.; Kumar P.; Thakare J.G.The welding of nuclear grade P91 and P92 steel plate of thickness 5.2 mm were performed using the autogenous tungsten inert gas (TIG) welding process. The welded joint of P91 and P92 steel plate were subjected to the varying post weld heat-treatment (PWHT) including the post weld heat treatment (PWHT) and re-austenitizing based tempering (PWNT). A comparative study was performed related to the microstructure evolution in fusion zone (FZ) of both the welded joint using the scanning electron microscope and optical microscope in a different condition of heat treatment. The hardness test of the FZ for both joints was also conducted in a different condition of heat treatment. P92 steel welded joint have observed the higher tendency of the ? ferrite formation that led to the great variation in hardness of the P92 FZ. The homogeneous microstructure (absence of ? ferrite) and acceptable hardness was observed after the PWNT treatment for both the welded joint. � 2018 Polish Academy of Sciences. All Rights Reserved.Item Dissimilar joining of CFEF steels using autogenous tungsten-inert gas welding and gas tungsten arc welding and their effect on ?-ferrite evolution and mechanical properties(2018) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.Ferritic/martensitic 9Cr-1Mo-V-Nb steel also designated as ASTM A335 used in construction of several components of power plants operating in temperature range of 600�650 �C. In present investigation, dissimilar weld joints of P91 and P92 steel were prepared using the autogenous tungsten inert gas welding (A-TIG) and multi-pass gas tungsten arc (GTA) welding process. A comparative was performed on evolution of ?-ferrite patches in weld fusion zone and heat affected zone (HAZ) of welded joints. The evolution of ?-ferrite patches was carried out in as-welded and post-weld heat treatment (PWHT) condition. PWHT was carried out at 760 �C for 2 h for both A-TIG and GTA welding process. For A-TIG weld joint higher yield strength, ultimate tensile strength (UTS) and peak hardness were measured due to higher heat input in single pass and higher carbon content in weld fusion zone. Higher heat input, fast cooling rate and higher weight percentage of ferrite stabilizer like vanadium (V) and niobium (Nb) in A-TIG weld joint were resulted in formation ferrite patches in weld fusion zone and heat affected zone. Higher weight percentage of V and Nb in A-TIG weld zone was resulted poor impact toughness of A-TIG weld fusion zone than GTA welds in as-welded condition. After the PWHT at 760 �C�2 h, Charpy toughness of A-TIG weld fusion zone (48 J) just meet the minimum required value as required by the EN: 1557:1997 (47 J). � 2017