Faculty Publications
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Item Influence of welding process parameters on microstructure and mechanical properties of friction stir welded aluminium matrix composite(Trans Tech Publications Ltd ttp@transtec.ch, 2017) Prabhu B, S.; Shettigar, A.K.; Karthik, K.; Rao, S.S.; Herbert, M.In this study, the effect of process parameters on microstructure and mechanical properties of friction stir welded aluminium matrix composites(AMC) have been explored. The results indicated that the recrystallized grain size at the bottom of the weld region is smaller than that at the top region due to difference in the heat transfer at the weld region. The joint strength of AMCs depends on proper selection of process parameters like tool rotational speed and welding speed. If process parameter values are beyond the optimal value, the joint strength decreases due to formation of defects. Maximum tensile strength is obtained for rotational speed of 1000 rpm and welding speed of 80mm/min. © 2017 Trans Tech Publications, Switzerland.Item Microstructural characterization and hardness evaluation of friction stir welded composite AA6061-4.5Cu-5SiC (Wt.%)(Defense Scientific Information and Documentation Centre, 2013) Shettigar, A.K.; Salian, G.; Herbert, M.A.; Rao, S.Recent developments in advanced materials research have led to the emergence of new materials having features like low density, high strength to weight ratio, excellent mechanical properties, heat and corrosion resistance. In friction stir welding (FSW), a non-consumable rotating welding tool is used to generate the frictional heat and plastic deformation of the material in the welding zone, which is in the solid state. The advantages of FSW as compared to the fusion welding are high joint strength, less defect weld, uniform distribution of grain structure in the weld zone and low power consumption. AA6061 with 4.5 % weight of copper and 5 % weight of SiC composite material has been prepared to conduct experiment and carry out characterization, evaluation of the mechanical properties. Micro-structural characterization of the weld zone is carried out by scanning electron microscope (SEM). Evaluation of hardness was also carried out across the weld zone. A successful method for FSW of AA6061-4.5(wt.%) Cu-5(wt.%) SiC has been developed. © 2013, DESIDOC.Item Additive manufacturing of an aluminum matrix composite reinforced with nanocrystalline high-entropy alloy particles(Elsevier Ltd, 2017) Karthik, G.M.; Panikar, S.; Janaki Ram, G.D.J.; Kottada, R.S.In the present work, a metal-metal composite consisting of aluminum-magnesium alloy AA5083 matrix and nanocrystalline CoCrFeNi high-entropy alloy reinforcement particles in 12 vol% was successfully friction deposited in multiple layers. The layer interfaces or the reinforcement/matrix interfaces showed no brittle intermetallic formation – thanks to the inert nature as well as the high strength and hardness of the high-entropy alloy reinforcement particles. The composite showed significantly higher tensile and compressive strengths as compared to standard wrought-processed alloy AA5083-H112 and offered a much better combination of strength and ductility when compared to conventional aluminum matrix composites reinforced with ceramic particles. The current study establishes friction deposition as a viable technique for additive manufacturing of novel high-performance composite materials. © 2016 Elsevier B.V.Item Application of particle swarm optimization and response surface methodology for machining parameters optimization of aluminium matrix composites in milling operation(Springer Verlag service@springer.de, 2017) Malghan, R.L.; Karthik, K.M.C.; Shettigar, A.K.; Rao, S.S.; D’Souza, R.J.Face milling is extensively used machining operation to generate the various components. Usually the selection of the process parameters are incorporated by trial and error method, literature survey and the machining hand book. This kind of selection of process parameters turns out to be very tedious and time-consuming. In order to overcome this there is a need to develop a technique that could be able to find the optimal process parameters for the desired responses in machining. The present paper illustrates an application of response surface methodology (RSM) and particle swarm optimization (PSO) technique for optimizing the process parameters of milling and provides a comparison study among desirability and PSO techniques. The experimental investigations are carried out on metal matrix composite material AA6061-4.5%Cu-5%SiCp to study the effect of process parameters such as feed rate, spindle speed and depth of cut on the cutting force, surface roughness and power consumption. The process parameters are analyzed using RSM central composite face-centered design to study the relationship between the input and output responses. The interaction between the process parameters was identified using the multiple regression technique, which showed that spindle speed has major contribution on all the responses followed by feed rate and depth of cut. It has shown good prediction for all the responses. The optimized process parameters are acquired through multi-response optimization using the desirability approach and the PSO technique. The results obtained from PSO are closer to the values of the desirability function approach and achieved significant improvement. © 2016, The Brazilian Society of Mechanical Sciences and Engineering.Item Microstructure evolution and mechanical properties of friction stir welded AA6061/rutile composite(Institute of Physics Publishing helen.craven@iop.org, 2019) Prabhu B, S.R.; Shettigar, A.K.; Herbert, M.A.; Rao, S.S.Present study explores the Friction stir welding (FSW) of rutile reinforced AA6061matrix composite using various combination of tool traverse speeds (60, 75 and 90 mm min-1), rotational speeds (750, 1000 and 1250 rpm) and tool pin profiles (Threaded cylindrical and Square profiled pin). FSW process variables have significant impact in controlling the mechanical properties of the joint by limiting the welding defects. It has been inferred from the study that tool rotational speed and tool traverse speed majorly affects the microstructure, joint quality, hardness and joint strength. The weld area showed the presence of four distinct regions usually found in FSW of aluminium matrix composites. The weld region exhibited fine equiaxed grains and uniformly distributed tiny reinforced rutile particles. Tool having square profiled pin shows improved joint properties in comparison with tool having threaded cylindrical pin. © 2019 IOP Publishing Ltd.Item Microstructure and mechanical properties of rutile-reinforced AA6061 matrix composites produced via stir casting process(Nonferrous Metals Society of China B12 Fuxing Road Beijing 100814, 2019) Prabhu B, S.R.; Shettigar, A.K.; Herbert, M.A.; Rao, S.S.A novel process of fabricating aluminium matrix composites (AMCs) with requisite properties by dispersing rutile particles in the aluminum matrix was studied. A novel bi-stage stir casting method was employed to prepare composites, by varying the mass fractions of the rutile particles as 1%, 2%, 3% and 4% in AA6061 matrix. The density, tensile strength, hardness and microstructures of composites were investigated. Bi-stage stir casting method engendered AMCs with uniform distribution of the reinforced rutile particles in the AA6061 matrix. This was confirmed by the enhancement of the properties of AMCs over the parent base material. Rutile-reinforced AMCs exhibited higher tensile strength and hardness as compared with unreinforced parent material. The properties of the composites were enhanced with the increase in the mass fraction of the rutile particles. However, beyond 3 wt.% of rutile particles, the tensile strength decreased. The hardness and tensile strength of the AMCs reinforced with 3 wt.% of rutile were improved by 36% and 14% respectively in comparison with those of matrix alone. © 2019 The Nonferrous Metals Society of ChinaItem Microstructure, microhardness, and tensile properties of hot-rolled Al6061/TiB2/CeO2 hybrid composites(South African Institute of Mining and Metallurgy, 2021) Iyengar, S.; Sethuram, D.; Shobha, R.; Koppad, P.G.TiB2 and CeO2 particle-reinforced Al6061 hybrid composites were manufactured using stir casting and hot rolling techniques. The base alloy and composites were hot-rolled at 500ºC and a 50% reduction was achieved through 12 passes. The effect of varying TiB2 and CeO2 particle additions on the microstructure and mechanical properties of the Al6061 matrix was studied. Scanning electron microscopy showed uniform dispersion of both the reinforcements, with good interfacial bonding. Microhardness and tensile properties like yield and tensile strength were found to be higher for hybrid composite with 2.5% TiB2 and 2.5% CeO2 compared to Al6061 alloy and other hybrid composites. The increased tensile strength is attributed to good dispersion and interfacial bonding between the particles and Al6061 matrix. Fracture analysis using a scanning electron microscope revealed ductile fracture for the Al6061 alloy and mixed characteristics of ductile-brittle fracture for hybrid composites. © 2021 South African Institute of Mining and Metallurgy. All rights reserved.Item Investigation on wear behavior of aluminium matrix micro and nanocomposites(Elsevier Ltd, 2022) Kumar, S.; Kumar, A.; Poddar, A.; Asthana, P.Aluminum matrix composites (AMCs) have a wide range of applications in aerospace, marine, and automobile because of their improved tribological and mechanical properties. In the present article, Al7075 alloy was used as the matrix material filled with micro (average size 50 μm) and nano (average size 80 nm) particles of Al2O3 (alumina). The same quantity of weight fractions of micro and nano alumina particles were injected into the semi-solid state of Al7075 aluminum alloy by the mechanical stir casting process. The developed composites have been investigated for specific wear rate (SWR) by using Pin on Disc Tribometer. The results of nano and micro composites have been compared at similar combinations of input parameters. The normal load, sliding distance, and sliding velocity were the input parameter for analyzing the SWR. The result shows that SWR increased with an increase in normal load and sliding distance. It has been found from the results that SWR is inversely proportional to sliding velocity. Also, results indicate that SWR of the developed AMCs containing nano alumina was found superior to that of the micro composite and base material. © 2021Item Optimization of FSW process parameters for maximum UTS of AA6061/rutile composites using Taguchi technique(Sharif University of Technology, 2022) Prabhu B, S.R.; Shettigar, A.; Herbert, M.A.; Rao, S.S.In the friction stir welding process, preferred joint property is vastly reliant on the selection of optimal welding conditions. The present study aims to use the Taguchi technique to find the optimal process conditions for achieving superior Ultimate Tensile Strength (UTS) in friction stir welded Aluminum Matrix Composite (AMC) joints. AMCs reinforced with rutile particles which have a potential application in the aerospace, automotive, and marine industries are used in the present work. Taguchi parametric design technique was used to identify the effect of rotational speed, tool traverse speed, and tool geometry on joint strength. Taguchi approach confined the optimum level of process variables and these variables were optimized. The investigation showed that the parameters within the selected value range will seriously affect the output. The predicted value of the output response was 155.48 MPa, which was validated by further experiments using the optimum process variables. Analysis Of Variance (ANOVA) results indicated that the UTS of the composite joint is mainly affected by the tool traverse speed followed by rotational speed, and tool geometry. The microstructural study unveiled that grain size is dependent on process variables and finer grains offer better joint properties. © 2022 Sharif University of Technology. All rights reserved.Item Experimental investigation and parametric optimization of FSW of mineral-reinforced AA6061 matrix composite(Institute of Physics, 2024) Prabhu B, S.R.; Herbert, M.A.In this work, rutile reinforced AA 6061 matrix composites were joined using friction stir welding and the process variables were optimized using Taguchi L27 orthogonal design of experiments. The rotational speed, axial force and tool tilt angle were the parameters taken into consideration. The optimum process variables were determined with reference to tensile strength, impact strength and hardness of the joint. The predicted optimal value of output responses was confirmed by conducting the confirmation run using optimum parameters. The optimal process variables combination values that resulted in improved mechanical properties were observed at a tool rotational speed of 1400 rpm, a tool tilt angle of 2 degree, and an axial force of 3KN. Scanning electron microscopy (SEM) analysis were used to probe the microstructures. © 2024 The Author(s). Published by IOP Publishing Ltd.