Faculty Publications
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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 Effect of Rotational Speeds on the Cast Tube During Vertical Centrifugal Casting Process on Appearance, Microstructure, and Hardness Behavior for Al-2Si Alloy(Springer Boston, 2015) Rao, R.A.; Tattimani, M.S.; Rao, S.S.The flow of molten metal plays a crucial role in determining casting quality. During rotation of the mold, melt flow around its inner circumference determines the final configurations and properties of the cast tube. In this paper, Al-2Si alloy is cast in the vertical mold at the various rotational speeds of the mold. The uniform cylinder tube is formed at a rotational speed of 1000 rpm, while before and beyond this speed, irregular-shaped cast tube is formed. Finally, fine structured grain size with high hardness value is found in uniform cast tube compared with others. © 2014, The Minerals, Metals & Materials Society and ASM International.Item Understanding Melt Flow Behavior for Al-Si Alloys Processed Through Vertical Centrifugal Casting(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2015) Rao, R.A.; Tattimani, M.S.; Rao, S.S.The objective of this article is to investigate the appearance, microstructure, and hardness of Al-Si alloys Al-12Si and Al-17Si in vertical centrifugal casting process. During rotation of the mold, molten metal flow affects the formation of uniform cylinder. In this study, flow of molten metal for Al-Si alloys at different rotational speeds is focused. It is found that for Al-17Si alloy a uniform cast tube is observed for 1000 rpm, whereas for Al-12Si it is at 1200 rpm; above and below these speeds, irregular cast tubes are formed. Finally, fine structured grain size with high hardness value is found in a uniform cast tube in comparison with others. © 2015 Taylor & Francis Group, LLC.Item 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 Experimental investigation of tensile fractography and wear properties of Al-12.5Si alloy reinforced with ZrO2 using spray deposition method(Elsevier Ltd, 2022) Patil, I.S.; Anarghya, A.; Rao, S.S.; Herbert, M.A.To improve the wear resistance of Al–12.5Si alloy, various percentage of zirconium oxide as reinforcement particles were used to produce metal matrix composites by spray deposition method. First, the developed metal matrix composites were subjected to dry sliding wear test using pin-on-disk apparatus under 60 N normal load with sliding velocity of 4.5 m/s at room conditions (∼28 °C and ∼60% relative humidity). The experimental results showed that the wear resistance of the developed composite can be optimized using a proper flight distance. In order to model the correlation between the wear properties and applied load, flight distance and sliding velocity of the metal matrix composites, a neural network model with genetic algorithm was developed. Second, the spray forming parameters such as flight distance, gas pressure, melt temperature and ZrO2 reinforcements were examined experimentally and analyse the insight on mechanical properties. Central composite design (CCD) with response surface methodology (RSM) was employed for selecting experimental matrix and latter perform detailed analysis. ZrO2 reinforcements and gas pressure showed major contribution, whereas negligible contributions with melt temperature and flight distance on hardness and UTS. The developed non-linear models for both responses showed similar effects and confirmed their relationship appears linear with good correlation coefficient equal to 0.978. The non-linear models derived empirical equations ensures accurate prediction with ten experimental cases equal to 1.21% for hardness and 6.09% for UTS, respectively. Multiple objective particle swarm optimization based crowding distance (MOPSO-CD) method integrated with desirability function approach (DFA) to determine the optimal spray forming conditions for achieving maximum hardness and UTS. The weights (0.05 for hardness and 0.95 for UTS) which ensures highest desirability value equal to 0.9958, and corresponding optimal spray forming conditions (melt temperature: 798 °C, flight distance: 0.35 m, gas pressure: 0.97 MPa and ZrO2 reinforcements: 11.6%) resulted in highest hardness of 80.4 HV and UTS of 173.2 MPa, respectively. © 2022 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.