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 Effect of mushy state rolling on age-hardening and tensile behavior of Al-4.5Cu alloy and in situ Al-4.5Cu-5TiB2 composite(Elsevier Ltd, 2011) Siddhalingeshwar, I.G.; Herbert, M.A.; Chakraborty, M.; Mitra, R.The effect of mushy state rolling on aging kinetics of stir-cast Al-4.5Cu alloy and in situ Al-4.5Cu-5TiB2 composite and their tensile behavior in solution-treated (495°C) or differently aged (170°C) conditions, has been investigated. As-cast or pre-hot rolled alloy and composite samples were subjected to single or multiple mushy state roll passes to 5% thickness reduction at temperatures for 20% liquid content. Peak-aging times of mushy state rolled composite matrices have been found as ?7.5-10% of that of as-cast alloy. Such enhancement in aging kinetics is attributed to homogeneity in Cu atom distribution as well as increase in matrix dislocation density due to thermal expansion coefficient mismatch between Al and TiB2, matrix grain refinement and particle redistribution, achieved by mushy state rolling. Uniform precipitate distribution in mushy state rolled composite matrices leads to greater peak-age microhardness with higher yield and ultimate tensile strengths than those in as-cast alloy and composite. © 2010 Elsevier B.V.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 Investigation of the effect of process parameters on the mechanical properties of friction stir additive manufactured (FSAM) AA8090 alloy(Elsevier B.V., 2025) D A P, P.; Shettigar, A.K.; Herbert, M.A.; Korgal, A.; Adiga, K.Friction Stir Additive Manufacturing (FSAM), an emerging technique, falls under the category of sheet lamination additive manufacturing. It employs a layer-by-layer fabrication where all the plates should be flat and of the same size. This process was developed to fabricate near-net-shaped components and refined microstructures. FSAM has been extensively used in the fabrication of aluminum alloys for aerospace applications. In this work, FSAM has been carried out for AA8090 aluminum alloy. AA8090 is the second-generation Al-Li alloy with 2.3 % Li, lightweight, 10 % lower density and 11 % higher modulus than the existing commercial 2014 and 2024 Al alloy. The experiments were carried out at rotational speed (1000 – 2000 rpm), traverse speed (45–55 mm/min) and 1° constant tilt angle. The macrostructure and microstructure analysis were carried out. This was followed by microhardness and tensile test analysis. The microhardness was carried out at nine points on each layer and tensile specimen was made according to ASTM E8 standard. The maximum reduction in grain size, which is 62 %, maximum hardness value 113 HV and maximum tensile value 346.8 MPa were observed at 2000 rpm. The size of the grains decreased from the top layer into the bottom layers. The maximum hardness for all the experiments was observed in the re-stir zone of the specimens. It was concluded that with increase in process parameters, better mechanical and microstructural properties can be achieved. The fractography analysis showed the presence of dimples and tear ridges indicating a ductile fracture. © © 2025. Published by Elsevier B.V.