Faculty Publications
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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 A review on wrought magnesium alloys processed by equal channel angular pressing(Inderscience Publishers, 2015) Muralidhar, M.; Narendranath, S.; Shivananda Nayaka, H.S.Magnesium and its alloys with severe plastic deformation (SPD) techniques are more attractive as structural parts in many industrial applications because of their advantages. In this paper, the importance of wrought magnesium alloys with their applications to accomplish the essential development of components is reviewed. In addition, the different approaches of equal channel angular pressing (ECAP) process for refining the grain size to achieve the ultrafine grained material on the bulk metals are discussed. Recent developments in the ECAP process are outlined clearly with their importance to overcome many complexities. Various factors like processing temperature of a specimen, die geometry, ram speed, back pressure and processing routes influencing during ECAP process of wrought magnesium alloys at different conditions such as channel angle and corner or outer arc angle are discussed. Finally, the properties of ECAP processed wrought alloys are outlined for improving the microstructure in structural parts. © © 2015 Inderscience Enterprises Ltd.Item Recent progress in equal channel angular pressing of magnesium alloys starting from Segal's idea to advancements till date – A review(KeAi Publishing Communications Ltd., 2023) Sekar, S.; Naik, G.M.; Narendranath, S.; Desai, V.Lightweight materials with high strength and ductility have immense potential in revolutionizing the automobile, aerospace, bio-medical and defence sector. Magnesium and its alloys are the candidates that are best suited for application in above mentioned sectors. However, achieving combination of properties such as high strength, good ductility and relatively better corrosion resistance in Mg alloys is still challenging. Indeed, equal channel angular pressing (ECAP) is one of the promising techniques that simultaneously enhances the mechanical properties and corrosion behaviour. In this review, an effort has been made to address the influence of ECAP on microstructure, mechanical properties, corrosion and galvanic corrosion of magnesium and its alloys. The reason for deviation of Mg alloys from Hall Petch relation is clarified. The necessity of tailoring the microstructure of Mg alloys in order to achieve desired properties is elucidated. In addition, the recommendations and future directions derived from summary and outlook of review are critiqued. © 2022 The AuthorsItem Effect of equal channel angular pressing on AZ31 wrought magnesium alloys(National Engg. Reaserch Center for Magnesium Alloys zhangdingfei@cqu.edu.cn, 2013) Muralidhar, A.; Narendranath, S.; Shivananda Nayaka, H.AZ31 wrought magnesium alloys are light weight materials which play an important role in order to reduces the environmental burdens in modern society because of its high strength to weight ratio, corrosion resistance, and stiffness and machinability. Applications of this material are mainly in structural component i.e., in constructions, automobile, aerospace, electronics and marine industries. In the present work, the microstructure characterization of the AZ31 alloys up to four ECAP passes at temperature of 573 K was observed for route Bc. Average grain size of the material was reduced from 31.8 ?m to 8 ?m after four ECAP passes. Mechanical properties of the alloy improved with increase in number of ECAP passes. Moreover, X-ray diffraction analysis was carried out for as received and ECAP processed material. © 2013 National Engineering Research Center for Magnesium Alloys of China, Chongqing University.Item Effect of combined grain refinement and modification on microstructure and mechanical properties of hypoeutectic, eutectic and hypereutectic Al-Si alloys(Inderscience Publishers, 2015) Shivaprasad, C.G.; Kiran Aithal, K.; Narendranath, S.; Desai, V.; Mukunda, P.G.The effect of melt treatment owing to the combined addition of grain refiner and modifier on the microstructure and mechanical properties of Al-Si alloys having 7% (hypoeutectic), 12% (eutectic) and 15% silicon (hypereutectic) is studied. 1 wt. % of Al-1Ti-3B Master alloy was used as grain refiner. For modification of eutectic Si, 0.2 wt. % of Al-10Sr Master alloy was added to hypoeutectic alloy and 0.4 wt. % is added to eutectic alloy as well as hypereutectic alloy. Furthermore, refinement of primary Si in hypereutectic alloy was achieved by addition of 0.04 wt. % of phosphorus. The goal of this investigation is to determine the influence of combined addition of grain refiner and modifier on mechanical properties and qualitatively correlate with the microstructural changes. © 2015 Inderscience Enterprises Ltd.Item Effect of Secondary Mg17Al12 Phase on AZ80 Alloy processed by Equal Channel Angular Pressing (ECAP)(Springer Netherlands, 2018) Muralidhar, M.; Narendranath, S.AZ80 alloy was subjected through Equal Channel Angular Pressing (ECAP) to refine the grains at three different temperatures 548 K, 573 K, and 623 K up to 4 passes for route Bc, where the specimen is rotated 90? counter-clockwise direction for each pass. In the present work, experiments have been continued with route Bc and the average grain size was obtained of 7 ?m, 9.5 ?m and 11.2 ?m for the temperatures of 548 K, 573 K, and 623 K respectively after 4 ECAP passes. The average grain size of the procured AZ80 alloy was found to be 44.5 ?m. Mechanical properties of AZ80 alloy have been improved to the corresponding various processing temperatures. X-ray diffraction studies have been done on a fourth ECAP processed specimen and compared with a zero pass specimen to know the phase transformation at different processing temperatures. Fracture behavior of each of the three materials was studied and it revealed brittle fracture by increasing the number of ECAP passes. © 2015, Springer Science+Business Media Dordrecht.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 Effect of ECAP Die Angles on Microstructure Mechanical Properties and Corrosion Behavior of AZ80 Mg Alloy(Springer New York LLC barbara.b.bertram@gsk.com, 2019) Naik, G.M.; Narendranath, S.; Kumar, S.S.S.In this article, the effect of channel angles on material properties was investigated during equal channel angular pressing of AZ80 magnesium alloy using processing route R at 325 °C processing temperature. Channel angles of 90° and 110° and common corner angle 30° have been considered for this study. It has been revealed that the channel angle has a significant influence on deformation homogeneity, microhardness, ultimate tensile strength, ductility and corrosion behavior of Mg alloys. Investigation with reference to as-received AZ80 Mg alloy indicates 18.47% improvement in UTS and 76.07% enhancement in ductility after processing through 3P-90° and 2P-110° ECAP, respectively. Also, the corrosion rate reduces to 89.47% after processing the sample with 3P-110° ECAP die. © 2019, ASM International.Item 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.