Faculty Publications
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Item Effect of FSW on microstructure and hardness of AA6061/SiC/fly ash MMCs(Elsevier Ltd, 2018) Patil, S.; Narendranath, S.; Dupadu, D.In this study 6 mm thick plates of aluminum matrix composites (AMCs) composed of AA6061/SiC (10 Wt. %) /fly ash (7.5 Wt. %) were butt welded using friction stir welding (FSW. Microstructural characterization of weld joints was conducted by using optical microscopy (OM) and scanning electron microscopy (SEM). The microstructure of the weld revealed the presence of four different zones like nugget zone (NZ), thermo mechanically affected zone (TMAZ), heat affected zone (HAZ) and base metal (BM). Nugget zone reveals homogenous distribution of fly ash and SiC particles. Rotating effect of FSW tool results in breaking of some array of grains present in the parent AMCs. Needle like phases present in the parent AMCs eliminated successfully by the incorporation of fly ash particles. Higher hardness is observed in the nugget zone compared to other zones. © 2018 Elsevier Ltd. All rights reserved.Item Studies on microstructure and mechanical characteristics of as cast AA6061/SiC/fly ash hybrid AMCs produced by stir casting(Elsevier Ltd, 2020) Patil, S.; Narendranath, S.; Dupadu, D.Fly ash has been receiving the extensive concentration as a strong reinforcing element for Aluminum Matrix Composites (AMCs) to strengthen the properties and cut the price of manufacturing. AA6061 reinforced with various weight percentages of fly ash particulates and a constant weight percentage of SiC were prepared by stir casting technique as it is one of the simplest and cost-effective method for producing AMCs. Wettability of SiC and Fly ash particles with the aluminum was enhanced by fly ash itself. The microstructure, hardness and tensile properties of manufactured AMCs were analyzed. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) discovered a harmonized dispersion of SiC and fly ash particles with superior bonding with the matrix material. The inclusion of fly ash particles in to aluminum matrix enhanced the microhardness and Ultimate Tensile Strength (UTS) of the AMCs. © 2019 Elsevier Ltd. All rights reserved.Item Effect of traverse speed on joint characteristics of FSWed HAMCs(Elsevier Ltd, 2020) Patil, S.; Narendranath, S.; Dupadu, D.The present work describes the evolution of microstructure and enhancement of mechanical properties of friction stir welded AA6061/SiC/FA Hybrid AMCs (HAMCs). Various joints were produced using different traverse speed from 30 mm/min to 80 mm/min. Microstructural analysis was carried out using Optical microscopy and scanning electron microscopy. Mechanical characteristics such as ultimate tensile strength (UTS) and microhardness (Hv) were studied. Sound quality joints were obtained by FSW without any defects. Results showed that the microstructure zones are divided in to nugget zone, thermomechanically affected zone, heat affected zone and base material zone. Uniform and fine grain formation took place at traverse speed of 60 mm/min indicating sufficient amount of heat input at this speed. Accordingly maximum joint efficiency of 90% is obtained at this traverse speed. © 2020 Elsevier Ltd. All rights reserved.Item Process parameter optimization for FSW of AA6061/SiC/fly ash AMCs using Taguchi technique(ICE Publishing subscriptions@icepublishing.com, 2018) Patil, S.; Narendranath, S.; Dupadu, D.In this research work, aluminum matrix composite (AMC) plates were welded using friction stir welding (FSW). AMCs contain AA6061 as a base metal with silicon carbide (SiC) and fly ash particles as reinforcements. The FSW process parameters considered in this work were tool rotational speed (revolutions/minute), tool traverse speed (millimeters/minute) and tool tilt angle (degrees). The Taguchi L9 orthogonal array was considered for optimizing the process parameters. Tensile strength and hardness were the two output responses obtained by analyzing joint efficiency and signal/noise ratio. An analysis of variance (Anova) study was conducted to identify the percentage contribution of each process parameter to the output responses. The Anova study concluded that among the three process parameters, tool rotational speed was the most dominant parameter in deciding the tensile strength and hardness of the FSW joints, followed by traverse speed and tool tilt angle. At the end, the results were validated by conducting additional experiments. © 2018 ICE Publishing: All rights reserved.Item Experimental evaluation of diamond burnishing for sustainable manufacturing(Institute of Physics Publishing helen.craven@iop.org, 2018) Sachin, B.; Narendranath, S.; Dupadu, D.Diamond burnishing is one of the most popular surface finishing technique used to achieve an excellent surface finish. The aim of the present study is to investigate the effect of process parameters in diamond burnishing of 17-4 PH stainless steel (PH SS) under cryogenic environment. The requirement of a sustainable environment for various machining processes urged to explore the importance of cryogenic burnishing over other cooling techniques. Surface modification was achieved by the application of liquid nitrogen (LN2) during diamond burnishing. The process parameters considered to reduce the surface roughness (Ra) and increase the surface hardness (H) are burnishing speed, burnishing feed and burnishing force. The diamond burnishing experiments were conducted based on the L9 orthogonal array. The significant parameters and the optimal level of each parameters were determined by using analysis of variance (ANOVA) and main effect plots respectively. Multi-response optimization has been carried out for cryogenic diamond burnishing of 17-4 PH stainless steel by using Taguchi's grey relation analysis (TGRA). From the TGRA, it was observed that at burnishing speed 73 m min-1, burnishing feed 0.048 mm/rev and burnishing force 150 N, improved diamond burnishing performance characteristics were obtained. An improvement in grey relation grade (GRG) was found to be 38.47%. Cryogenic diamond burnishing has led to modifications in the microstructure and also an improvement in the subsurface hardness of the material. © 2018 IOP Publishing Ltd.Item Sustainable diamond burnishing of 17-4 PH stainless steel for enhanced surface integrity and product performance by using a novel modified tool(Institute of Physics Publishing helen.craven@iop.org, 2019) Sachin, B.; Narendranath, S.; Dupadu, D.Amajor sustainability concern of manufacturing industries is indiscriminate use of lubrication, energy consumption, and allied cost. To avoid such kind of situation and to improve the product quality, sustainable manufacturing concept has been widely used. One of the popular technique is the use of Minimum Quantity Lubrication (MQL) as a working fluid to improve the product performance. Diamond burnishing underMQLenvironment is an exceptional technique to obtain the improved surface integrity of the material without affecting operator health and environmental aspects. In this work, the impact of control factors on the surface integrity characteristics namely surface roughness, surface topography, surface hardness, surface morphology, residual stress and subsurface hardness of 17-4PHstainless steel have been studied underMQLenvironment by using a novel modified tool. It was ensured that minimum surface roughness of 0.05 ?mand maximum surface hardness of 405HV had been achieved. Improved surface finish and surface hardness were obtained for a diamond sphere radius of 4mmand 3mmrespectively under optimal diamond burnishing conditions. The obtained investigational results confirm that a novel modified tool was successfully implemented to enhance the surface integrity characteristics under theMQLenvironment. © 2019 IOP Publishing Ltd.Item Effect of working parameters on the surface integrity in cryogenic diamond burnishing of 17-4 PH stainless steel with a novel diamond burnishing tool(Elsevier Ltd, 2019) Sachin, B.; S, N.; Dupadu, D.The productivity of the components is adversely affected by the poor surface integrity characteristics as a consequence of the generation of high temperature in the burnishing zone. The abundant use of conventional lubricants causes environmental pollution and health problems. To overcome these issues, cryogenic cooling has been used across the world to reduce the temperature generated in the burnishing zone. It is well known that most of the accidents which involve aero engines have revealed that the reason for this may be due to the failure of the first stage of compressor blades. Hence aerospace material, 17-4 precipitation hardenable (PH) stainless steel can be used in aero engines to minimize the failure occurring due to foreign object damage. In the present study, the effect of cryogenic diamond burnishing on the surface integrity characteristics such as surface roughness, surface hardness, surface morphology, surface topography, subsurface microhardness, and residual stress of 17-4 pH stainless steel have been investigated with a novel diamond burnishing tool and also it has been related to dry and minimum quantity lubrication (MQL) environments. From the experimental results of diamond burnishing process, surface roughness was observed to be reduced by 33%–50%, 34%–51% and 25%–40% in the cryogenic cooling environment in contrast with MQL and dry environments. Similarly, the surface hardness improvement in a cryogenic cooling environment was found to be 5%–7%, 6%–10%, and 6%–9%, in comparison with MQL and dry environments respectively. © 2019 The Society of Manufacturing EngineersItem Microstructure, Hardness and Tensile Properties of Friction Stir Welded Aluminum Matrix Composite Reinforced with SiC and Fly Ash(Springer editorial@springerplus.com, 2019) Patil, S.; Narendranath, S.; Dupadu, D.In the present work, aluminum alloy 6061/SiC/fly ash aluminum matrix composites were welded successfully using friction stir welding process. Microstructure of weld joints was examined using optical microscope and scanning electron microscope. Mechanical properties namely, microhardness and ultimate tensile strength of the joints were studied. The results were correlated to microstructural changes caused by friction stir welding process. Microstructure in the stirred zone exhibits the uniform distribution of SiC and fly ash particles. Especially fine grains were formed on the advancing side than on the retreating side, due to the different variation between tool direction and welding direction. Higher hardness value is observed on the advancing side (132 Hv) than on the retreating side (124 Hv). Transverse tensile test of weld sample exhibits higher joint efficiency of 85.06% with respect to ultimate tensile strength. Fracture study reveals ductile mode of failure. Weld joints got fractured in heat affected zone on the retreating side, which indicates the weakest part of the weld joint. Based on thermodynamic analysis, the optimum heat input was found to be 756 J mm?1, resulting in higher strength of weld joints due to uniform distribution of reinforcement particles in the nugget zone. © 2018, Springer Nature B.V.Item Analysis of the Effect of Friction Stir Welding Parameters on Characteristics of AA6061 Composites using Response Surface Methodology(Springer, 2021) Patil, S.; Dupadu, D.; Narendranath, N.Response surface methodology (RSM) is used for mathematical modeling of friction stir welding parameters for joining AA6061 composite material. Characteristics of joints were examined through response characteristics such as ultimate tensile strength (UTS) and microhardness (HV) using RSM. Microstructure examination was carried out using optical microscopy, scanning electron microscopy and electron backscattered diffraction, and results exhibit variation in the grain size diameter. Specifically, lower nugget exhibits fine grains with maximum hardness compared to middle nugget and upper nugget. Analysis of variance (ANOVA) results indicate good match between actual values and predicted values with R2 of 0.91 and 0.96, respectively, for UTS and HV, and better joint efficiency of 90% is obtained. © 2021, The Indian Institute of Metals - IIM.