Research Publications
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Item Abrasive wear analysis of RZ5/TiC in-situ composites: a statistical approach(2019) Mehra D.; Mahapatra M.M.; Harsha S.P.Purpose: The RZ5 mg alloy is used in automotive and aerospace applications including helicopter gearboxes and aircraft components. These components are prone to the wear as per the demands. The present work is the study of the significance of hard particle/ceramic, i.e. titanium carbide (TiC) in RZ5 mg alloy to protect the machine components from wear. Design/methodology/approach: The abrasive wear analysis of in-situ RZ5-TiC magnesium matrix composite is considered for the study. The primary focus of the present work is to analyze the effects of varying control parameters, i.e. Wt.% of TiC, sliding distance and applied load on the responses, i.e. weight loss and coefficient of friction. Full factorial design of the experiment based on statistical analysis is used. Findings: It is observed that the individually Wt.% of TiC and sliding distance show the comparatively significant effect on both responses. Similarly, the interaction between sliding distance and Wt.% of TiC indicated the considerable impact on weight loss. The regression equations are developed and validated for estimating responses. It is observed that the percentage errors are not appearing more than 10 per cent of responses. Therefore, the close agreement between measured and predicted values shows the adequacy of the model. The control factor is optimized using multi-response optimization. The variations of the order of 2.47 and 2.35 per cent in target value of the coefficient of friction and weight loss are achieved. Originality/value: The current manuscript provides a detailed abrasive wear statistical analysis of RZ5-TiC composite. The influence of control parameters on the responses using the full factorial design, the main effect plots and interaction effects are presented. � 2019, Emerald Publishing Limited.Item Role of evolving microstructure on the mechanical behaviour of P92 steel welded joint in as-welded and post weld heat treated state(2019) Pandey C.; Mohan Mahapatra M.; Kumar P.; Thakre J.G.; Saini N.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 ? ferrite phase in the weld fusion zone and the coarse grained heat affected zone. The PWNT completely removed the ? ferrite patches from the microstructure whereas the PWDT treatment merely reduced the range of the hardness of the ? ferrite from 179 to 301 HV (as welded) to 204�228 HV. � 2018 Elsevier B.V.Item 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 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 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). � 2017Item Effect of welding process and PWHT on ?-ferrite evolution in dissimilar P91 and P92 steel joint(2018) Pandey C.; Mohan Mahapatra M.; Kumar P.; Mulik R.S.; Saini N.; Gopal Thakre J.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 ?-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. � 2018 Elsevier Ltd.Item A brief study on ?-ferrite evolution in dissimilar P91 and P92 steel weld joint and their effect on mechanical properties(2018) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.; Thakre J.G.; Vidyarthy R.S.; Narang H.K.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 joint of P91 and P92 steel were prepared using the autogenous tungsten inert gas (A-TIG) welding and multi-pass gas tungsten arc welding (GTAW) process. A comparative study was performed on evolution of ?-ferrite patches in weld fusion zone and heat affected zones (HAZs) of welded joints. The evolution of ?-ferrite patches was studied in as-welded and post-weld heat treatment (PWHT) condition. PWHT was carried out at 760 �C for tempering time of 2 h and 6 h, for both A-TIG and GTA weld joints. It was observed that presence of higher content of ferrite stabilizer in P92 steel promote the formation of ?-ferrite patches in weld fusion zone as well as HAZs. To study the effect of welding process and PWHT, Charpy V impact energy and microhardness tests were performed. For microstructure characterization, field-emission scanning electron microscope (FESEM) and optical microscope were utilized. � 2017 Politechnika Wroc?awskaItem Characterization of P92 Steel weldments in as-welded and PWHT conditions: Room-temperature tensile tests and microhardness measurements led to improving the ductility of the weld joints(2018) Saini N.; Pandey C.; Mahapatra M.M.; Mulik R.S.P92 steels have been developed as a candidate material for power plant components that operate in a temperature range of 620o-650�C. A heterogeneous microstructure formation across the P92 weldments makes the wettability of P92 steel a serious issue. The other problem that arises in P92 steel weldments is the formation of ?-ferrite due to the presence of a higher weight percentage of ferrite stabilizers such as V and Nb. as well as W and Mo. In the present work, the shielded metal arc welding (SMAW) process was utilized to prepare the P92 steel weld joints. After welding, postweld heat treatment (PWHT) was performed at 760�C for 2 h. To characterize the weld joints, room-temperature tensile tests and microhardness measurements were performed in the as-welded and PWHT conditions. The subsequent PWHT resulted in a decrease in the hardness gradient across the weldments. The PWHT resulted in enhancing the : ductility of the weld joints. � 2018 American Welding Society. All rights reserved.Item Design of experiment (DOE) study of hydroxyapatite-coated magnesium by cold spray deposition(2015) Hasniyati M.R.; Zuhailawati H.; Ramakrishnan S.; Dhindaw B.K.; Mohd Noor S.N.F.In this study, hydroxyapatite powder was sprayed onto pure magnesium plate using a simple modified cold spray process. The effects of process parameters (i.e.standoff distance, surface roughness, substrate, substrate heating temperature and number of spray)were studied using 2k-1 factorial design.Analysis of variant (ANOVA) were used to determine the significant of process parameters on the coating. Thickness of coating, nanohardness and elastic modulus were chosen as the responses for assessing the most significant parameters that affected the hydroxyapatite coated onto pure magnesium plate. HAP particles have found to be bonded well in sample of run 11 while sample of run 4 show poor bonding between HAP particles and magnesium substrate. The effect of individual variables on the response was briefly discussed. � (2015) Trans Tech Publications, Switzerland.Item Effect of Cooling Slope Angle on Microstructure of Al-7Si Alloy(2015) Acharya M.; Deepak Kumar S.; Mandal A.Attempts were made to obtain non-dendritic microstructure in Al-7Si alloy by pouring the melt on mild steel cooling slope. The melt was poured into the slope at different angles�15�, 30�, 45� and 60�. The pouring temperatures chosen were 630 �C, 640 �C and 650��C corresponding to melt superheat of 15 �C, 25 �C and 35��C. The results indicate that a lowest slope angle of 15o along with superheat of 15��C leads to microstructure with minimum grain size of 33�?m and shape factor of 0.81. The findings showed that lower slope angles would yield minimum grain size, are in contradiction to earlier studies, which could be related only to the lowest possible superheats used in the present study. � 2015, The Indian Institute of Metals - IIM.