Research Publications
Permanent URI for this collectionhttps://idr.iitbbs.ac.in/handle/2008/2
Browse
66 results
Search Results
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 Microstructure and mechanical properties of D-Gun sprayed Cr3C2-NiCr coating on P91 steel subjected to long term thermal exposure at 650 �c(2019) Thakare J.G.; Pandey C.; Mulik R.S.; Mahapatra M.M.Thermally sprayed 75Cr3C2-25NiCr coating is applied on structural components to improve corrosion, oxidation and erosion behaviour at high temperature. In order to understand the microstructural and mechanical behaviour of coating a long term investigation was carried out at 650 �C. The Objective of the present work is to study the effect of long term heat treatment (i.e. 650 �C/ 3000 h) on various characteristics of the detonation gun sprayed 75Cr3C2-25NiCr coating. Hardness and nanoindentation studies were carried out on Cr3C2-NiCr coating after fixed time intervals. The morphological and microstructural features of the coated surface were characterized using scanning electron microscope (SEM). The phases formed during the long term exposure were identified by x-ray diffraction (XRD) technique. The coating showed the presence of various Cr, Ni, based oxides, Fe and Ni based spinels. Vanadium, niobium, and molybdenum showed maximum tendency to diffusion from substrate to the coating. Hardness of the coating reached a maximum value of 870 HV after 2160 h of exposure. The hardness of coating observed an initial drop in hardness due to carbide coarsening which was recovered by precipitation of carbides from the solid solution. � 2019 IOP Publishing Ltd.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 Influence of TiC on dry sliding wear and mechanical properties of in situ synthesized AA5052 metal matrix composites(2019) Samal P.; Vundavilli P.R.; Meher A.; Mahapatra M.M.In this paper, aluminium metal matrix composites were synthesized through in situ process in which aluminium alloy 5052 (AA5052) and titanium carbide were used as matrix and reinforcement materials, respectively. The microstructural characterization and formation of stable TiC phases were analyzed with the help of field emission scanning electron microscope, X-ray diffraction analysis, respectively. The 9% TiC-reinforced MMCs had shown a considerable improvement, i.e. 32% increase in hardness, 78% in ultimate tensile strength and 116% increase in yield strength when compared with the base alloy. The tensile fracture of the specimens shows dimples, voids, cracks, and ridges indicating the brittle nature. Further, the dry sliding wear properties of the composites were studied with the help of a pin-on-disc wear testing machine. The composite with 9% TiC exhibited a decrease in volumetric wear loss by 24% when compared with the base alloy at a load of 30 N. With increase in the TiC content and applied load, the COF values decreased linearly for the composites. The 9% TiC-reinforced composites show an abrasive mode of wear mechanism as a result of formation of deep grooves with no plastic deformation. With the improvement obtained in the wear properties, this metal matrix composite can be considered as a replacement for the conventional brake disc material used in the automobile industry. � The Author(s) 2019.Item 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 Thermomechanical analysis of tungsten inert gas welding process for predicting temperature distribution and angular distortion(2019) Narang H.K.; Pandey C.; Thakare J.G.; Saini N.; Mahapatra M.M.; Jha P.K.In present research work, discussions have been made to predict the bead geometries and shape profiles of weldments using statistical regression modeling and fuzzy logic techniques. However, the regression and fuzzy logic modeling techniques do not take into account the actual physical properties and phenomena that occur in welding. Moreover, techniques such as regression and fuzzy logic modeling are not suitable for predicting the transient temperature distribution and distortion of arc welded joints. To predict the transient temperature distributions, peak temperature distribution, and residual deformation in welding, deterministic modeling techniques such as thermomechanical analysis are preferred. However, while performing thermomechanical analysis of welded joints, size and reinforcement dimensions of the weld bead need to be incorporated into the model for accurate prediction of transient temperature distributions and distortions. In this work, circularly spread moving heat source has been used for transient thermal modeling of tungsten inert gas (TIG) welding process. In the subsequent sections of this article, the weld thermomechanical analyses for TIG square butt joints are discussed to predict the temperature distributions and angular distortion. The weld dimensions such as weld width, weld depression, and weld bulging have shown great influence on the angular distortion patterns. � 2019 Society of Naval Architects and Marine Engineers. All rights reserved.Item Microstructural characterization and experimental investigations into two body abrasive wear behavior of Al-7079/TiC in-situ metal matrix composites(2019) SV S.; Mahapatra M.M.; Mulik R.S.High strength Al-7079 aluminum metal-matrix composites with 5, 7 and 9 wt.% of TiC particulate reinforcement were procured by in-situ melt reaction method. Scanning electron microscopy (SEM) and XRD analysis were conducted in order to confirm the presence of titanium carbide (TiC) particles and homogeneity inside the aluminum matrix. The parameters like applied load (9.8�29.4 N), sliding distance (1000�2000 m), sliding velocity (1.5 m/s) and SiC-P-600 grit paper (25 �m) were used in this study. The influence of sliding distance, applied load and wt.% of (TiC) reinforcement on in-situ Al-7079 under two body abrasion was investigated. Further, the obtained results were compared with the base Al-7079 alloy. It was examined that, the in-situ reinforced composites exhibited significantly greater wear resistance of 20�60% compared to conventional as cast Al-7079 base matrix. Experimental results confirmed that the wt.% of TiC and sliding distance had higher influence on coefficient of friction and the weight loss was highly affected by the applied load. Further the wear mechanisms involved in the worn surfaces were demonstrated through atomic force microscopy and SEM analysis throughout the surfaces. � IMechE 2019.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 Prior-austenite grain refinement in P92 steel using double austenitization treatment(2019) Saini N.; Mulik R.S.; Mahapatra M.M.The experimental investigation of 'double austenitization based normalizing and tempering' (DNT) heat treatments on tensile behavior and microstructural morphology of the CSEF/M P92 steel was carried out and compared it with the 'conventional normalizing and tempering' (CNT) heat treatment. The CNT treatment was performed at the normalizing temperature of 1040 �C for 60 min, followed by air cooling and then tempered at 760 �C for 120 min, followed by the air cooling. The DNT treatment involved the initial austenitizing at the temperature 950, 1100 and 1150 �C for 60 min, followed by the water quenching for higher dislocation density and then further austenitized at 1040 �C for 60 min followed by the air cooling. After the double austenitization based normalizing, tempering was performed at 760 �C for 2 h. The double austenitized samples are named as DNT 1 (950 �C), DNT 2 (1100 �C) and DNT 3 (1150 �C). The fine grain structure was obtained for the DNT 3 treatment. The fracture surface morphology of tensile tested specimen was studied using the field emission scanning electron microscope (FESEM). The results of tensile tests were obtained superior for the DNT treatment as compared to CNT treatment. Microstructure also showed the refinement of the grain size and lath width after the DNT treatment. � 2018 IOP Publishing Ltd.Item 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 Ltd