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 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 Influence of Route-R on wrought magnesium AZ61 alloy mechanical properties through equal channel angular pressing(National Engg. Reaserch Center for Magnesium Alloys zhangdingfei@cqu.edu.cn, 2014) Muralidhar, M.; Narendranath, S.A new fundamental route entitled 'Route-R' is introduced to refine the grains in the material through Equal Channel Angular Pressing (ECAP) process. In route R, specimen is inverted to the original position in each ECAP pass. In the present work, AZ61 alloy is processed using ECAP process for three different fundamental routes mainly route A, route Bc, and route R. ECAP experiment is carried out on AZ61 alloy at lower temperature of 483 K up to two passes. Microstructural characterization is evaluated on unECAPed and ECAPed specimens for three routes. Average grain size of the alloy is to be reduced from 66 ?m to 16 ?m, 14.1 ?m and 10 ?m for route A routes Bc, and route R respectively. Vickers microhardness of the alloy is found to be 60 HV for as received material. This microhardness of the alloy is increased to 71 HV, 72 HV, and 74 HV for route A, route Bc, and route R respectively. Mechanical properties of the AZ61 alloy are observed to be route R is providing maximum YS, UTS, and percentage elongation than other route A and route Bc. Tensile fracture topography of the specimen is analyzed using three different routes for two passes. © 2014 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 Evaluation of WEDM performance characteristics of Inconel 706 for turbine disk application(Elsevier Ltd, 2015) Sharma, P.; Dupadu, D.; Narendranath, S.Inconel 706 is a newly developed superalloy, which offers high mechanical strength alongwith easy fabricability thus making it suitable for turbine disk applications. Although Inconel 706 exhibits a substantial increase in stress rupture and tensile yield strength compared to other superalloys, its conventional machining yields poor surface finish and low dimensional accuracy of the machined components. Hence, wire electrical discharge machining (WEDM) of Inconel 706 has been performed and various performance attributes such as material removal rate (MRR), surface roughness (SR), recast surface, topography, microhardness, microstructural and metallurgical changes of the machined components have been evaluated. The experimental results revealed that servo voltage, pulse on time, and pulse off time greatly influence the MRR and SR. Due to high toughness of Inconel 706, no micro cracks were observed on the machined surface. Micro voids and micro globules are significantly reduced at low pulse on time and high servo voltage. But, there is a propensity of thick recast layer formation at high pulse on time and low servo voltage. EDAX analysis of recast surface exposed the existence of Cu and Zn which have migrated from the brass wire. The subsurface microhardness was changed to 80. ?m due to significant thermal degradation. © 2015 Elsevier Ltd.Item Effect of Wire Material on Productivity and Surface Integrity of WEDM-Processed Inconel 706 for Aircraft Application(Springer New York LLC barbara.b.bertram@gsk.com, 2016) Sharma, P.; Dupadu, D.; Narendranath, S.Inconel 706 is a recently developed superalloy for aircraft application, particularly in turbine disk which is among the most critical components in the gas turbine engines. Recently, wire electrical discharge machining (WEDM) attained success in machining of gas turbine components which require complex shape profiles with high precision. To achieve the feasibility in machining of these components, the research work has been conducted on Inconel 706 superalloy using WEDM process. And, the effect of different wire materials (i.e., hard brass wire, diffused wire, and zinc-coated wire) on WEDM performance characteristics such as cutting speed, surface topography, surface roughness, recast layer formation, residual stresses, and microstructural and metallurgical alterations have been investigated. Even though, zinc-coated wire exhibits improved productivity, hard brass wire was found to be beneficial in terms of improved surface quality of the machined parts. Additionally, lower tensile residual stresses were obtained with hard brass wire. However, diffused wire has a moderate effect on productivity and surface quality. Under high discharge energy, higher elemental changes were observed and also the white layer was detected. © 2016, ASM International.Item Effect of wire diameter on surface integrity of wire electrical discharge machined Inconel 706 for gas turbine application(Elsevier Ltd, 2016) Sharma, P.; Dupadu, D.; Narendranath, S.Inconel 706 superalloy has established itself in the field of gas turbine industry because of its easy fabricability combined with high mechanical strength. Due to its high stress rupture and tensile yield strength, conventional machining of this superalloy exhibits poor surface and low dimensional accuracy of the machined components. It is well known that most of the gas turbine components include complex shaped profile with high precision and hence, wire electrical discharge machining (WEDM) of Inconel 706 has been performed to achieve the feasibility in manufacturing of complex shaped components for gas turbine application. In the current investigation, the effect of wire diameter on WEDM performance characteristics such as cutting speed, surface roughness, surface topography, recast layer formation, microhardness, microstructural and metallurgical changes have been evaluated. It was investigated that smaller diameter wire is advantageous over the larger diameter wire since it improves productivity as well as surface quality of the machined components under the same settings of control parameters. In addition, smaller diameter wire has shown comparatively lower recast layer thickness, minimum hardness alteration and shorter manufacturing time. The XRD result has confirmed the presence of residual stress within WED machined component. © 2016 The Society of Manufacturing EngineersItem Influence of ageing time on hardness, microstructure and wear behaviour of AISI2507 super duplex stainless steel(Institute of Physics Publishing helen.craven@iop.org, 2017) Davanageri, M.; Narendranath, S.; Kadoli, R.The effect of ageing time on hardness, microstructure and wear behaviour of super duplex stainless AISI 2507 is examined. The material was solution treated at 1050 °C and water quenched, further the ageing has been carried out at 850 °C for 30 min, 60 min and 90 min. The chromium (Cr) and molybdenum (Mo) enriched intermetallic sigma phase (?) were found to precipitate at the ferrite/ austenite interface and within the ferrite region. The concentration of intermetallic sigma phase (?), which was quantified by a combination of scanning electron microscopy and image analysis, increases with increasing ageing time, leading to significant increase in the hardness. The x-ray diffraction (XRD) and energy dispersive x-ray (EDX) was employed to investigate the element distribution and phase identification. Wear characterstics of the aged super duplex stainless steel were measured by varying normal loads, sliding speeds, sliding distance and compared with solution treated (as-cast) specimens. Scanning electron microscopy was used to assist in analysis of worn out surfaces. The outcomes suggested that the increase in percentage of sigma phase increases hardness and wear resistance in heat-treated specimens compared to solution treated specimens (as-cast). © 2017 IOP Publishing Ltd.