BITS Faculty Publications
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Item Enhancement of mechanical properties and corrosion resistance of friction stir welded joint of AA2014 using water cooling(Elsevier, 2017-01) Sinhmar, SunilAn investigation on the microstructure, mechanical properties, and corrosion behavior of friction stir welded joint of AA2014 in natural cooled (NC) and water cooled (WC) conditions have been reported. Optical microscopy, field emission scanning electron microscopy (FESEM) with Energy dispersive X-ray spectroscopy (EDS), Vicker's microhardness, tensile testing, X-ray diffraction (XRD), and electrochemical potentiodynamic polarization corrosion test (Tafel curve) were carried out to characterize the friction stir weld joints in both the cooling conditions. Water cooling resulted in higher strength and microhardness of friction stir weld joint compared to the natural cooling. The width of heat affected zone was reduced by the use of water cooling during friction stir welding (FSW) and minimum hardness zone was shifted towards weld center. The corrosion test was performed in 3.5% NaCl solution. Corrosion resistance of water cooled joint was found higher than natural cooled FSW joint. The precipitation behavior of weld nugget and heat affected zone impacts the corrosion resistance of FSW joint of AA 2014. Hardness, tensile, and corrosion properties of FSW joints produced under NC and WC conditions have been discussed in the light of microstructure.Item A study on corrosion behavior of friction stir welded and tungsten inert gas welded AA2014 aluminium alloy(Elsevier, 2018-04) Sinhmar, SunilThe present study comprises the comparison of the electrochemical behavior of friction stir weld (FSW) joint and tungsten inert gas (TIG) weld joint of AA2014 using immersion test, potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). Weld thermal cycles and microhardness were correlated with corrosion behavior of the weld joints. TIG weld joint showed lower corrosion resistance than FSW joint. Heat affected zone was the most corrosion susceptible region in both type of weld joints. Optical microscopy, FESEM, TEM and XRD analysis were performed to discuss the corrosion behavior in light of the microstructure.Item Effect of weld thermal cycle on metallurgical and corrosion behavior of friction stir weld joint of AA2014 aluminium alloy(Elsevier, 2019-01) Sinhmar, SunilFriction stir welding of AA2014 aluminium alloy was performed at seven different speed combinations. Weld thermal cycles were measured at all the speed parameters and corresponding peak temperatures were observed at higher tool rotation speed and lower welding speed. Hardness and tensile tests were performed to study the mechanical properties of the weld joints. Corrosion behavior was studied using immersion, Tafel and electrochemical impedance spectroscopy tests. Optical microscopy, FESEM, XRD and transmission electron microscopy were used to investigate the metallurgical behavior of the weld joints. Microhardness and corrosion resistance were found higher at low rotation speed and high traverse speed. Corrosion behavior has been discussed in light of microstructure.Item Mechanical behavior of FSW joint welded by a novel designed stationary shoulder tool(Elsevier, 2020-03) Sinhmar, SunilA novel stationary shoulder friction stir welding (SSFSW) tool was developed with provision for automatic removal of plasticized material entering into the shoulder during the welding. Main objective of this tool design was to obtain a symmetrical weld joint with narrow heat affected zone. Mechanical and metallurgical properties of AA2014 aluminium alloy SSFSW joint were compared with the conventional FSW joint. Sound weld joint with enhanced mechanical properties were obtained by the stationary shoulder tool. Optical microscopy, FESEM analysis along with EDS, transmission electron microscopy, XRD analysis, microhardness and toughness test were performed on both types of weld joint. Weld thermal cycle and heat generation were analyzed for stationary shoulder and conventional FSW tool and it was found that the SSFSW tool shoulder generates lesser heat than conventional FSW tool.Item Art of friction stir welding to produce weld joint without rotation of shoulder with narrow heat-affected zone and high corrosion resistance(Sage, 2020-08) Sinhmar, SunilThis present study uses an indigenously designed non-rotating shoulder friction stir welding (NRSFSW) tool to weld AA2014 aluminium alloy. This tool is harnessed with a penetrated material removal mechanism. Generally, the heat-affected zone (HAZ) is the most severely affected region in the conventional FSW (CFSW) joint of heat-treatable aluminium alloys. The prime novelty of this work is to reduce the width of most corrosion susceptible region of the FSW joint using a non-rotating shoulder tool. The corrosion behaviour of the NRSFSW joint has been investigated and compared to the CFSW joint. The NRSFSW tool resulted in focused heat input which eventually reduced the width of the HAZ and improved corrosion resistance as compared to the CFSW tool.Item Influence of a Stationary Shoulder Friction Stir Welding Tool on the Mechanical and Corrosion Properties of AA2024 Aluminum Alloy Joints at Different Parameter Values(Springer, 2023-11) Sinhmar, SunilSound weld joints of similar AA2024 aluminum alloy plates of 6 mm were achieved unprecedentedly at different rotational (386-1216 rpm) and traverse speeds (13-90 mm/min) using an indigenously developed stationary shoulder friction stir welding (SSFSW) tool. Results indicate a smooth and bowl-shaped symmetrical nugget zone (NZ) with fine equiaxed grains. The grains as well as the nugget zone width vary with the speed variation. A change of 16% in the width of NZ is observed with an increase in traverse speed from 13 to 90 mm/min. The SSFSW tool reduces the width of the weakest region of the weld joint, known as the heat-affected zone, by almost 50%. The SSFSW joint produced at 931-90 mm/min shows the highest value (101 HV) of the minimum hardness region as compared to other parameters. The SSFSW tool shifts the weakest region toward the NZ, as substantiated by the fracture location of the tensile samples. In addition, SSFSW joints show higher corrosion resistance in NZ due to recrystallized fine grains as compared to HAZ. The SSFSW tool reduces the width of the most severely corrosion-affected region and, hence, improves the corrosion resistance of the joint.Item Enhancement of the Mechanical and Corrosion Behaviour of FSW Joints Using a Novel Particle Reinforcement Approach(Springer, 2024-01) Sinhmar, SunilReinforcement of external particles during friction-stir welding (FSW) is significantly used to improve the weld joint’s performance. The present study involves reinforcement of the external particles in the weld joint without the aid of grooving or drilling. The FSW joint of AA2014 aluminium alloy has been reinforced with boron carbide (B4C) powder particles. The performance of the joint was investigated in terms of mechanical behaviour using tensile and microhardness tests as well as corrosion (electrochemical) behaviour using immersion, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) tests. The presence of boron carbide particles in the joint improves the tensile strength, microhardness, and corrosion resistance. In light of the microstructure, the impact of the reinforcement of these particles on the weld joint performance has been thoroughly discussed.Item Effect of variation in power input on dissimilar materials (Cu-Al) laser welding for battery manufacturing(Elsevier, 2024-06) Sinhmar, SunilBattery manufacturing inherently requires the joining of dissimilar materials. The performance of a joint is significantly derived from the joining technique as well as the process parameters, which, in turn, determine the life of the product. The current study discusses the efficacy of laser welding to develop dissimilar joints of thin sheets of Al and Cu for battery applications at varying power inputs. Thin sheets of aluminium and copper were welded using laser power inputs of 2.0 kW, 2.1 kW, and 2.2 kW. A power input of 2.1 kW results in 86 % higher weld penetration than the 2.0 kW. High power input results in through-thickness penetration, which drastically affects the mechanical strength of the joint. A weld joint developed at 2.1 kW shows a higher shear load of 800 N among all the power input parameters. An intermetallic layer forms at the weld interface for all three power inputs. However, the width of the intermetallic layer increases with the laser power input.Item Friction Stir Processing of AA 7039 Alloy(2014-12) Sinhmar, SunilFriction stir processing (FSP) is an effective solid state surface modification technique used to improve the surface properties of metals like aluminium, and titanium controlled structural refinement. In present work, friction stir processing of 5 mm thick plate of Al-Zn-Mg alloy (AA 7039) was carried out using a conical pin and overlap of 50%. Modified surfaces were characterized in respect of macrostructure, microstructure, hardness and tensile properties. It was observed that friction stir processing refined the microstructure of AA 7039 alloy and increased the ductility (%elongation). However, tensile strength and hardness were found to be adversely affected. Hardness has been found to be increased with number of passes during friction stir processing.Item Investigation of mechanical and corrosion behavior of friction stir weld joint of aluminium alloy(Elsevier, 2019) Sinhmar, SunilFriction stir welding of AA2014 aluminium alloy was performed at 931 rpm and 41 mm/min speed. Weld joint properties were compared with the base metal. Optical microstructure and FESEM analysis with energy dispersive spectroscopy (EDS) were performed. Microhardness and tensile tests were performed to study the mechanical behavior of base metal and FSW joint. Direct current based corrosion test was carried out to study the corrosion behavior. Mechanical performance of AA2014 was reduced after the welding. Corrosion resistance of the weld joint was higher than the base metal. Presence of precipitates affected the performance of base metal and weld joint.