Faculty Publications
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Item Correlational Study of Ultimate Tensile Stress and Hardness of Friction Stir-Welded Al–Ce–Si–Mg Aluminum Alloys(Springer Nature, 2024) D’Souza, A.D.; Herbert, M.A.; Rao, S.S.In this research article, an analysis of correlation between mechanical properties of aluminum alloy such as ultimate tensile stress and Vickers hardness is carried out. Research analysis shows that hardness and UTS have a direct relationship. Tool rotation speed also directly impacts hardness and UTS values by controlling the amount of heat generated and hence extent of plasticization and grain refinement in the region of the weld. According to the research results, the plane surfaces of the square profiled pin of the tool aid in introducing a pulsing effect, which contributes to improved strength of weld connection. When compared to other tool profiles, a higher dynamic-to-static ratio attained with the triangular profiled pin tool results in greater material sweeping. As a result, the highest UTS and hardness values were obtained for welding connections created with the triangular profile pin tool. The study shows that the various input process parameters pertaining to tool revolving velocity, welding velocity, and tool-pin profile have a similar relationship on both hardness and ultimate tensile strength of weldment connection obtained with friction stir weld process. Hence, a similar trend or correlation has been observed in the variation of hardness and UTS. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.Item Influence of rotational speed of centrifugal casting process on appearance, microstructure, and sliding wear behaviour of Al-2Si cast alloy(Korean Institute of Metals and Materials, 2010) Mukunda, P.G.; Rao, S.; Rao, S.S.Although the manner in which the molten metal flows plays a major role in the formation of the uniform cylinder in centrifugal casting, not much information is available on this topic. The flow in the molten metal differs at various rotational speeds, which in turn affects the final casting. In this paper, the influence of the flow of molten metal of hyper eutectic Al-2Si alloys at various rotational speeds is discussed. At an optimum speed of 800 rpm, a uniform cylinder was formed. For the rotational speeds below and above these speeds, an irregular shaped casting was formed, which is mainly due to the influence of melt. Primary á-Al particles were formed in the tube periphery at low rotational speed, and their sizes and shapes were altered with changes in rotational speeds. The wear test for the inner surface of the casting showed better wear properties for the casting prepared at the optimum speed of rotation. © KIM and Springer.Item Analysis of surface roughness and hardness in titanium alloy machining with polycrystalline diamond tool under different lubricating modes(Universidade Federal de Sao Carlos, 2014) Revankar, G.D.; Shetty, R.; Rao, S.S.; Gaitonde, V.N.The present work deals with the investigation on machining of difficult-to-machine material titanium alloy (Ti-6Al-4V) using poly crystalline diamond (PCD) tool under different coolant strategies, namely dry, flooded and MQL. Taguchi technique has been employed and the optimization results indicated that MQL lubricating mode with cutting speed of 150 m/min, feed rate of 0.15 mm/rev, nose radius of 0.6 mm and 0.25 mm depth of cut is necessary to minimize surface roughness and dry mode with cutting speed of 150 m/min, feed rate of 0.15 mm/rev, nose radius of 0.6 mm and 0.75 mm depth of cut is necessary to maximize surface hardness. The results indicate the substantial benefit of the minimum quantity of lubrication (MQL) and justify PCD inserts to be the most functionally satisfactory commercially available cutting tool material for machining titanium alloys for better surface finish and hardness.Item Development of novel cutting tool with a micro-hole pattern on PCD insert in machining of titanium alloy(Elsevier Ltd, 2018) Rao, C.M.; Rao, S.S.; Herbert, M.A.The development of a novel cutting tool that had a micro-hole pattern on their rake and flank face of cutting tool surface has found wider potential in the field of manufacturing. Micro-hole pattern features on a tool rake face help in controlling the tribological characteristics of the cutting tool. Micro-holes with the different number of holes orientation, diameter and depth were fabricated using the advanced application of the electrical discharge super drilling machine with the view to assist lubricant penetration and retention. A comparative study has been conducted between micro-hole patterned Polycrystalline Diamond (PCD) cutting insert and the commercially available PCD cutting insert. The effect of micro-hole pattern on the machining of Titanium alloy (Ti-6Al-4 V) is investigated with the application of the Minimum Quantity Lubrication (MQL) method in turning operation. Vibration signals were captured in feed force direction and measured using the tri-axial accelerometer. The cutting temperature, tool-wear, and chip-morphology were measured with an infrared thermometer and Scanning Electron Microscope (SEM). It was found that micro-hole textured inserts reduced the friction on the rake face resulting in the decrease of vibration up to 30–50%. The cutting temperature, tool wear and surface roughness were reduced to 30%, 50% and 40%, respectively. The conical and helical chips were produced in micro pool lubrication system. The friction coefficient can be minimized at the tool-chip interface by using liquid lubrication method. There is no unfavourable effect on the performance of cutting tools having holes on the cutting tool surface. All these parameters led to the improvement in the tool life. © 2018Item Assessment of influence of process parameters on properties of friction stir welded Al-Ce-Si-Mg aluminium alloy(Institute of Physics Publishing helen.craven@iop.org, 2019) D’Souza, A.D.; Rao, S.S.; Herbert, M.A.The research on friction stir welding is mainly focused on welding of aluminium alloys. The material of interest in this research is an aluminium alloy known as Al-Ce-Si-Mg aluminium alloy. The FSW of this alloy finds applications in aerospace industry like joining of aircraft structure parts such as fuselage, cladding and engine components and in automotive industry for welding of parts of body structure and engine. The quality of the weld produced by FSW such as macrostructure defects, average grain size, ultimate tensile stress and weld zone hardness etc are dependent on input parameters like tool revolution, tool feed rate and tool pin profile. The weld defects like tunnel hole, worm hole and pin holes were not predominant in the tool revolution range of 800 to 1200 rpm and tool feed rate range of 10 to 20 mm min-1. The maximum ultimate stress was found to be lesser in the low and high tool revolution and tool feed rates compared to the medium speeds. The maximum value of UTS noted was 102.55 MPa for the weld at a tool revolution of 800 rpm and tool feed rate of 20 mm min-1 with a triangular pin profile tool, giving a joint efficiency of 67%. The Vickers hardness values were less at lower and higher speed ranges of tool revolution and tool feed rates for all the tool pin profiles used. The maximum value of Vickers hardness was noted for a tool revolution of 1000 rpm and tool feed rate of 20 mm min-1 with a triangular pin profile tool. The lowest grain size was observed for the tool revolution of 1000 rpm and tool feed rate of 20 mm min-1 with a triangular pin profile tool, indicating the inverse relation between hardness and grain size. In all the experiments it was observed that the triangular pin profile tool gives the best results at medium tool revolution and tool feed rate ranges. © 2019 IOP Publishing Ltd.Item Mechanical and microstructural analysis of a AlSi-ZrO2 metal matrix composite using optimized artificial neural network and experimental data(Elsevier Ltd, 2021) Patil, I.S.; Anarghya, A.; Rao, S.S.; Herbert, M.A.Spray deposition methods has emerged as an alternative to powder metallurgy and ingot routes. This research aims to study the effect of flight distance as a potential key factor that changes the optimum percentage of aluminium silicon- zirconium oxide in terms of mechanical and microstructural properties. The alloy is sprayed at varying the flight distance from 320 mm to 480 mm. The composite were prepared by spray deposition technique and effects on microstructural properties were examined. The aluminium silicon- zirconium oxide composite was subjected to hot isostatic pressing for reducing the porosity of the deposit from 14.4% to 8.2%. A series of experimental study were carried out in the laboratory by varying the flight distance from 320 mm to 480 mm for aluminium silicon- zirconium oxide composite to characteristic loading. In this paper, an optimized artificial neural network using genetic algorithm are developed to predict the mechanical behaviour for aluminium silicon- zirconium oxide composites. Based on the experimental data, the ANN models were developed, trained and tested. The microstructure of the AlSi-ZrO2 composite consisted of finely divided globular shaped eutectic Si uniformly distributed in the Al matrix. With addition of zirconium oxide composition to AlSi alloy, the tensile strength and micro hardness increased from 123 MPa to 147 MPa and, 48 HV to 72 HV, respectively. The preferred flight distance for the current study is found to be 420 mm. Microstructural images obtained at flight distance consist of co-existing primary Si phase and needle like eutectic Si. The physical properties, such as tensile strength, compressive strength, yield strength, micro hardness and porosity of sprayed aluminium silicon- zirconium oxide can hence be adjusted by setting the optimized flight distance. The developed ANN-GA method proved to be accurate, reduced time and efficient to predict the numerous samples and it will help materials designers to design their future experiments effectively. © 2021 Elsevier LtdItem Effect of zirconium oxide particulate composites with Al-Si on the microstructural and mechanical properties of hot pressed, spray forming and stir casting methods(Taylor and Francis Ltd., 2023) Patil, I.S.; Anarghya, A.; Rao, S.S.; Herbert, M.A.; Kushwaha, R.This research work aims to investigate the aluminum and silicon alloy reinforced with the ZrO2 powder particles, which has been fabricated using stir casting and spray deposition method. The mechanical properties, micro hardness and microstructure of the developed metal matrix composite is investigated. The microstructural results indicate that the rich interface among the AlSi-ZrO2 particles and depicts the agglomeration of reinforced phase resulting to poor wettability of ZrO2 and observed decohesion. The mechanical testing results indicate that the tensile strength increases with the percentage of ZrO2. Moreover, as cast composites exhibit reverse tendency in compressive and hardness values. The highest compressive values for as cast and hot-pressed composites were 380 MPa and 337 MPa for 10% ZrO2. The highest tensile strength of 191.83 MPa was obtained for 5% ZrO2 as cast composite and 164 MPa for 15% ZrO2 hot pressed composite. It is to note that as cast composite method represented more homogenous data compared to the hot-pressed composites. Hot pressed samples exhibited the reduction in the porosity compared to the as cast. The developed method proved to be accurate, reduced time and efficient to predict the numerous samples. © 2021 Engineers Australia.Item Fretting wear behavior on LPBF processed AlSi10Mg alloy for different heat treatment conditions(Elsevier Editora Ltda, 2024) Nanjundaiah, R.S.; Rao, S.S.; Praveenkumar, K.; Prabhu, T.R.; Shettigar, A.K.; Gowdru Chandrashekarappa, M.; Linul, E.To widen the industrial application of additively manufactured (AM) parts, the study of fretting wear behavior is essential, as it ensures the safety and reliability that drive innovation in design and materials. This study explores the fretting wear behavior of the as-built and heat-treated state of AlSi10Mg alloy fabricated, viz., laser powder bed fusion (LPBF). Initially, the as-built and T5, T6, and stress-relieved (SR) heat-treated samples were examined using scanning electron microscopy (SEM) to gain insights into the microstructural changes. The as-built samples exhibited a higher hardness level (135 HV) primarily due to the presence of very fine microstructure of the α-Al cellular matrix with embedded Si. The α-Al cellular structure dissolved with various heat treatments, and Si particles coarsened. The hardness decreased to 85, 79, and 67 HV for the T5, T6, and SR conditions, respectively. Subsequently, fretting tests were conducted on the samples, applying various normal loads of 10, 50, and 100 N. Further, the samples were characterized by the coefficient of friction (COF), worn surface morphology, and wear volume loss. The investigation showed that the as-built material showed less wear volume loss under all loading conditions than the heat-treated conditions. Furthermore, the T5 heat treated sample had a lower wear volume when compared to the T6 and SR heat-treated samples. The heat-treated sample exhibits compressive stress, whereas the LPBF processed, the as-built sample shows tensile stress. © 2024 The Authors