Faculty Publications
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Item Mechanical and Microstructural Properties of Multi-Axially Forged LM6 Aluminium Alloy(Pleiades journals, 2019) Sajjan, S.S.; Kulkarni, M.V.; Ramesh, S.; Sharath, P.C.; Rajesh, R.; Kumar, V.In the present investigation, commercially available light metal aluminium LM6 alloy was processed by Multi-axial forging (MAF) at ambient temperature. MAF was carried out to an equivalent strain in 0.83, 1.66 and 2.4 i.e., 6 passes, 12 passes and 18 passes, respectively. The mechanical properties like tensile test, compression test, hardness and microstructural characterization were studied in processed and unprocessed samples. Ultimate tensile strength (UTS) and ductility improved from 137 to 185 MPa and 3 to 6.2% for as-received to processed samples, respectively. After 18 passes of MAF, the compression strength (CS) has improved from 342 to 530 MPa. Hardness increased as the number of forging passes increases as compared to unprocessed samples. Optical microscopy images were used to study microstructure observations, the average grain size is reduced from 60 to 2 μm for as-received to processed samples, respectively. Strength and hardness increased because of the grain refinement for the processed samples and the introduction of the high amount of dislocation density into the material during the MAF process. Fracture study was conducted by utilizing scanning electron microscopy, dimples on tensile fracture surfaces revealed that ductile mode of fracture. © 2019, Springer Nature Singapore Pte Ltd.Item Microstructural and Size Accuracy Study of Electrochemical Machined Aluminium Alloy Features(Springer Nature, 2019) Sahu, R.K.; Pal, V.K.; Kumar, P.The present work focuses on the machining of aluminium 6061 alloy workpiece electrodes using Electro-Chemical Machining (ECM) by varying the control parameters like voltage, feed rate and machining time. Scanning electron microscopy study is carried out to examine the microstructure of the craters of definite morphology machined on the workpiece. Optimum parameter settings to maximize the length, width and depth of the obtained features were studied individually through a parametric experimental design layout of Taguchi. The results reveal that the optimal parameter settings are found to be different for each performance objective. As a result, the grey Taguchi method has been adopted to convert the three objectives into a single objective and by considering the performance objectives concurrently, the process parameters were optimized. The favourable parameters to maximize the responses are determined to be voltage—15 V, feed rate—0.3 mm/min and machining time—5 min. Further, the effect of process parameters on the microstructure and size accuracy of the Al alloy features is studied. © 2019, Springer Nature Singapore Pte Ltd.Item A Review on Mechanical and Microstructure Properties of Reinforced Concrete Exposed to High Temperatures(Springer, 2021) Goudar, S.K.; Santhosh, S.K.; Das, B.B.This paper presents the recent research progress on the response of concrete exposed to fire or high temperatures. The main highlight of this review paper is a compilation of previously reported data regarding the variations in mechanical properties and microstructure properties of concrete when exposed to high temperatures. The concrete structures get deteriorated at the macro- and microscopic levels due to high-temperature exposure. The macro-level damages can be measured with degradation in mechanical properties such as the reduction in compressive strength, weight loss, changes in elastic properties, reduction of bond strength in reinforced concrete, etc. The macro-cracks on the surface of concrete causes spalling which can be observed after exposing the concrete samples to more than 300 ℃. The compressive strength of the concrete reduces slightly till 400 ℃, and when the temperature increased to 600 ℃, there was an exponential reduction in the compressive strength of concrete. Another important parameter is bond strength degradation, which plays a crucial role in durability issues. To understand the deterioration phenomenon and changes in mechanical properties, the changes at the level of the microstructure of concrete need to be understood. Dehydration of products causes deterioration of mechanical properties and weight loss of concrete when exposed to high temperatures. At different temperatures, the microstructure changes and the response of hydration products such as calcium hydroxide (CH), CSH gel, unhydrated cement and capillary water reported by previous researchers are compiled and discussed. © 2021, Springer Nature Singapore Pte Ltd.Item Influence of Tool Probe Offset and Traverse Speed on Microstructure and Mechanical Properties of Friction Stir Weld Dissimilar Joints of AA2024-T351 and AA7075-T651(Springer Nature, 2020) Anil Kumar, K.S.; Murigendrappa, S.M.; Kumar, H.The effect of tool probe offset and varying traverse speed on the mechanical and metallographic characteristics of friction stir weld dissimilar joints of AA2024-T351 to AA7075-T651 in butt joint configuration produced using taper-threaded tool with constant tool rotation speed, 650 rpm and plunge depth, 6.2 mm are investigated. The tool traverse speed was varied from 20 to 120 mm/min along the weld length with the different tool probe offset condition. Optical microscopy and scanning electron microscopy are used to characterize the grain size and microstructural modification at the weld nugget zone (WNZ). The effect of different tool offset conditions in conjunction with varying traverse speed results in banded structure of alloys, partial material mixing and unmixed region at the WNZ. The combination of tool offset distance of 1 mm towards AA7075-T651 with traverse speed, 110 mm/min yields maximum ultimate tensile strength, 436 MPa, yield strength, 375 MPa, elongation, 14% and weld joint efficiency, 92%. © 2020, Springer Nature Singapore Pte Ltd.Item Corrosion Characteristics of Metal Matrix Composites(Elsevier, 2021) Bhat Panemangalore, D.; Bhat K, U.To tackle significant challenges posed by industries and environment with respect to materials degradation, we need to have a clear understanding of the impact of corrosion in different components. Composites are designed for a specialized application using different material combinations. This article presents an overview on different corrosion characteristics of metal matrix composites. Several types of corrosion have been addressed along with different corrosion methodologies. Corrosion of aluminum MMCs, magnesium MMCs, etc., have been discussed, along with different processing related problems. Different aspects involved in determining the corrosion behavior of metal matrix composites have been addressed. © 2021 Elsevier Ltd. All rights reserved.Item Mechanical Properties and Microstructural Characteristics of Friction Stir Welded Aluminium Matrix Composite(Springer Nature, 2021) Subramanya, B.; Shettigar, A.; Herbert, M.A.; Rao, S.S.Nowadays, friction stir welding process appears a promising technique to weld difficult materials by conventional welding techniques. Present study aims to analyse the significance of process variables on the mechanical behaviour of aluminium matrix composite joined by friction stir welding (FSW) technique. FSW is carried out at different welding conditions using conventional threaded cylindrical tool (TC). Microstructural study indicates several tiny reinforced particles are uniformly distributed in the nugget region. Recrystallization and grin refinement are observed in the weld area. Nugget region exhibits higher hardness compared to the base material. Joint efficiency of up to 89% is obtained for the FS-welded composite. The fracture surface reveals that the matrix undergoes a ductile fracture whereas reinforced particles exhibit brittle fracture. © 2021, Springer Nature Singapore Pte Ltd.Item Microstructural Aspects of Metal-Matrix Composites(Elsevier, 2021) Bhat Panemangalore, D.B.; Shabadi, R.Microstructures play a very important role in deciding the end properties of an alloy or a composite. Optimized microstructure could be obtained by a careful choice of processing technique and selection of materials. Metal-matrix composites (MMCs) that have been developed significantly over the last five decades possess valuable properties. MMCs can be tailored with myriad of variations to suit for a particular application and hence they belong to a unique class of materials. However, it is important to understand the microstructural aspects to understand the behavior of the component in different environmental and working conditions. This article presents an overview on different microstructural aspects of metal matrix composites. © 2021 Elsevier Ltd. All rights reserved.Item Processing techniques of recycled aggregates(Elsevier, 2025) Trivedi, S.S.; Das, B.B.; Barbhuiya, S.Three essential components of every modern-day growth are preservation of natural aggregate resources, green construction, and the safeguarding of the environment. One such endeavor is the incorporation of recycled aggregate (RA) in concrete. Because of the issues with its strength and durability, the use of RA is typically limited to inferior load constructions. With appropriate management and effective processing methods, the application can be expanded to high-strength concrete. In the present manuscript, the current C&D waste management practices adopted by various nations are highlighted alongside different in-action legislations are thoroughly reviewed for developing an understanding about the basic elements involved in the debris management. In addition, some of the latest and novel recycling approaches are investigated such as autogenous cleaning method, air and hydraulic jigging technologies, and advanced dry recovery system. To investigate the nature of RA processed from aforementioned technologies, the inherent properties of aggregates such as specific gravity, water absorption, density, and abrasion values alongside microstructure performance through scanning electron microscopy (SEM) are comprehensively reviewed and presented. Based on the extensive investigation, it is recognized that effective C&D waste management can be accomplished using certain techniques such as circular procurement and green construction. Furthermore, there is a requirement for specified processing methods that enhances the physio-chemical properties. Also, the surface morphology can be improved using combined crushing and ball milling approaches. Overall, it is recommended to implement vertical shaft crushing and ball milling for the development of fine RA whereas for the coarse RA fractions, multistage jaw crushing and advanced dry recovery (ADR) system are some of the finest processing approaches. © 2025 Elsevier Ltd. All rights reserved.Item Thermal analysis and microstructure of ZA8 alloy solidifying against chills(Springer India sanjiv.goswami@springer.co.in, 2012) Ramesh, G.; Prabhu, K.N.Thermal analysis during solidification of ZA8 alloy against copper, hot die steel and stainless steel chills instrumented with thermocouples was carried out in the present work. The investigation showed that the chill material and coating had a significant effect on the cooling curve of the casting. When casting was solidified against chills, the liquidus and eutectic start temperature of the casting remained nearly the same whereas eutectoid transformation occurred at a higher temperature. Cooling rate curve of the casting solidified against coated chill indicated that formation of solid shell and subsequent re-melting in the case of high thermal conductivity coated chill whereas in lower thermal conductivity coated chill, the re-melting of solid shell was absent. It was found that chilling during solidification causes the morphology of dendrites transform to nearly rounded shape with refinement of lamellar eutectic.Item Microstructure and mechanical properties new magnesium-zinc-gadolinium alloys(Minerals, Metals and Materials Society 184 Thorn Hill Road Warrendale PA 15086, 2016) Seetharaman, S.; Tekumalla, S.; Lalwani, B.; Patel, H.; Bau, N.Q.; Gupta, M.Magnesium based materials are effective for structural/component weight reduction in automotive applications. However, their real time applications are limited because of their inadequate mechanical properties, especially the absolute strength and creep resistance. In this regard, the formation of thermally stable ternary compounds is believed to positively influence the properties of Mg-Zn-RE alloys. In this study, new Mg alloys containing Zn and Gd (Mg-2.0Zn-0.5Gd and Mg-3.4Zn-0.8Gd, in at.%) were developed using disintegrated melt deposition technique followed by hot extrusion. The developed alloys were investigated for their microstructural and mechanical properties in hot-extruded conditions. The mechanical properties examined under indentation, tension and compression loads indicated improved mechanical performance due to Zn and Gd addition. The observed mechanical properties are presented using structure-property relationship. © © 2016 by The Minerals, Metals & Materials Society. All rights reserved.