Faculty Publications
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Item Structure-property correlation of weld metal zone and interface regions of cold metal transfer welded dissimilar Al-Mg-Mn alloys joint(Elsevier Ltd, 2021) Rajeshkumar, R.; Niranjani, V.L.; Devakumaran, K.; Banerjee, K.Cold Metal Transfer (CMT) welding of dissimilar Al-2.6 Mg-0.5Mn (A5754) and Al-4.5 Mg-1.0Mn (A5083) aluminium alloys has been performed with ER5356 filler wire. The microstructure and mechanical properties of the weld-metal zone (WMZ) and interface regions are correlated. The microstructure reveals epitaxial grains at the edge of the partially molten zone (PMZ) and equiaxed dendritic structure at the center of the WMZ. Energy dispersive spectroscopy (EDS) results show that the WMZ and PMZs are composed of α-Al, Al3Mg2and Al6Mn phases. The WMZ exhibits higher hardness and strength due to the existence of equiaxed dendrite structure, dilution effect and absence of defects. The interface region of A5083 side exhibits higher hardness and strength due to the presence of finer grains and higher volume fine secondary phases in the PMZ and HAZ of this side than at the other side. Fracture surface of all the samples exhibits dimples indicating a ductile fracture. © 2021 Elsevier Ltd. All rights reserved.Item Hydrogen-Induced Cold Cracking in High-Frequency Induction Welded Steel Tubes(Springer Boston, 2016) Banerjee, K.Detailed investigation was carried out on 0.4C steel tubes used for the telescopic front fork of two-wheelers to establish the root cause for the occurrence of transverse cracks at the weld heat-affected zone of the tubes. Fractographic and microstructural observations provide evidences of delayed hydrogen-induced cracking. The beneficial microstructure for avoiding the transverse cracks was found to be the bainitic-martensitic, while martensitic structure was noted to be deleterious. © 2016, The Minerals, Metals & Materials Society and ASM International.Item Role of interfacial microstructure on mechanical properties of cold metal transfer welded dissimilar A6061-T6 and A6082-T6 joints(Elsevier B.V., 2020) Rajeshkumar, R.; Devakumaran, K.; Banerjee, K.A6061-T6 and A6082-T6 dissimilar aluminium alloys are welded using CMT (Cold metal transfer) process and the interface microstructure of the individual alloys is correlated with mechanical properties. Microstructures indicate that dendrites next to the PMZ (Partially melted zone) of A6082-T6 side are finer than the dendrites next to the PMZ of A6061-T6 side. Liquation at grain boundaries and within the grains is clearly visible in the PMZ of A6061-T6 interface, whereas the PMZ of A6082-T6 interface does not reveal liquation phenomenon at grain boundaries and grain interiors. Among the interface regions, the A6082-T6 side shows superior mechanical properties as compared to the A6061-T6 side. © 2020 Elsevier B.V.Item Fusion boundary microstructure evolution and mechanical properties of cold metal transfer welded dissimilar A5754 and A5083 joint(Elsevier B.V., 2021) Rajeshkumar, R.; Niranjani, V.L.; Devakumaran, K.; Banerjee, K.Fusion boundary microstructure evolution and its effect on tensile properties of cold metal transfer (CMT) welded joint of dissimilar A5754 and A5083 is studied. Non-dendritic equiaxed fine zone (EQZ) is newly evolved and located between PMZ and weld metal zone (WMZ). The Si films are distributed as continuous layers at grain boundaries (GBs) of EQZ, these films are comparatively less and are distributed in a non-continuous manner at GBs of partially melted zone (PMZ). EQZ of A5083 side exhibits finer grains than A5754 side. The narrower EQZ width, finer grains at EQZ, finer dendrites at WMZ interface and larger distribution of secondary phase particles at PMZ and heat affected zone (HAZ) increase strength of A5083 side. © 2020 Elsevier B.V.Item Identification of critical material thickness for eliminating back reflected shockwaves in laser shock peening – A numerical study(Elsevier Ltd, 2021) Mylavarapu, P.; Bhat, C.; Perla, M.K.R.; Banerjee, K.; Gopinath, K.; Jayakumar, T.Laser Shock Peening (LSP) is one of the emerging surface treatment processes being considered for inducing beneficial compressive surface residual stresses in fatigue critical components. Owing to the ease in handling multiple parameters during optimization of process parameters, simulation based parameterization studies using finite element (FEM) based numerical models are widely gaining importance. Most of the LSP modeling performed so far considered infinite elements in both thickness and lateral directions. However, infinite elements in thickness direction would neglect the deleterious effect of shock wave back reflections for certain sample thicknesses. These back reflections have been reported to result in formation of subsurface cracks in the specimen. Therefore, in this study, using an alternative modeling strategy, effect of thickness on the back reflection of shock waves and its subsequent effect on residual stresses induced are discussed. A 2-D axi-symmetric model with infinite elements in lateral direction and finite elements in thickness direction is developed to simulate a single spot LSP process using ABAQUS/CAE FEM package. It is found that there exists a critical material thickness depending on spot diameter below which the effects of back reflection are predominant. © 2021 Elsevier LtdItem Evolution of non-dendritic equiaxed zone and its influence on mechanical properties of tungsten inert gas welded dissimilar A6061-T6 and A6082-T6 joint(Elsevier B.V., 2021) Rajeshkumar, R.; Niranjani, V.L.; Devakumaran, K.; Banerjee, K.Non-dendritic equiaxed zone (EQZ) evolution and its influence on tensile properties of tungsten inert gas (TIG) welded joint of dissimilar A6061-T6 and A6082-T6 are studied. EQZ is observed in A6061-T6 interface whereas it is completely absent at the A6082-T6 interface. The distribution of fine Si eutectic phases along the grain boundaries (GBs) of EQZ of A6061-T6 interface appearing as discontinuous fine particles but as a continuous layer at most of the dendrite boundaries (DBs) at the center of the weld metal zone (WMZ). The improvement in strength of A6082-T6 interface compared to A6061-T6 interface is mainly attributed to the absence of EQZ in the former interface. © 2021 Elsevier B.V.Item Recrystallisation Characteristics of a Cu-Bearing HSLA Steel Assessed Through High Temperature Compressive Deformation(Defense Scientific Information and Documentation Centre, 2023) Kumar, A.; Prasad, T.V.V.S.V.; Karthik, V.V.; Banerjee, K.; Gopinath, K.; Balamuralikrishnan, R.Dynamic (DRX) operative during deformation and static recrystallisation (SRX) operative after deformation are considered responsible for the changes in microstructure and texture of deformed materials. Especially in the case of advanced steels that are required in the form of plates of various thicknesses, hot rolling is the main manufacturing process during which the steel undergoes DRX under the rolls and SRX between rolling passes/strands. Knowledge on DRX and SRX characteristics of such steels is crucial for optimisation of hot rolling parameters,achieving the desired microstructure and consequently the targeted mechanical properties.In this study, certain key aspects of both dynamic (DRX) and static recrystallisation (SRX) behaviour of aCu-bearing HSLA steel, which was developed at DMRL, have been explored through high temperature deformation studies using Gleeble thermo-mechanical simulator. Through uniaxial compression testing in the austenitic regime, domains of continuous and discontinuous DRX prevalent in the steel were identified and critical parameters for initiation of dynamic recrystallisation viz., critical strain (ec), critical stress (sc), peak stress (sp) and peak strain (ep) were determined as a function of temperature and strain rate. SRX characteristics were assessed through uniaxial double hit compression tests with fixed strain rate and strain per hit but at different temperatures and with different imposed intermediate static recrystallisation (ISRT) times. From the fractional softening data, parameters such as time for 50 % recrystallisation, t0.5, temperature for 50 % recrystallisation, T0.5, and activation energy, QSRX have been estimated.Although the steel exhibited good plastic deformation characteristics, the results suggest that the role of copper in retarding recrystallisation is significant. © 2023, DESIDOC.Item Comparative study of diode laser welding of solid-solution/precipitation-strengthened Fe-Ni-Cr-based superalloys(Taylor and Francis Ltd., 2025) Kumar, H.; Banerjee, K.; Aqeel, M.; Shariff, S.M.This study investigates autogenous diode laser welding of two differently strengthened Fe-Ni-Cr superalloys: solid-solution strengthened Incoloy 800 and precipitation-strengthened Incoloy A286. Effects of laser power, welding speed, and defocusing distance on weld bead geometry, microstructure, and mechanical properties were comprehensively analyzed. Butt weld joints produced with optimum and similar heat input conditions achieved joint efficiencies comparable to their base metals. Microstructural analysis of fusion zone revealed columnar dendrites of ?-(Ni,Fe) in both alloys, with A286 showing segregation of Ti, Cr, and Mo intermetallics at interdendritic regions, while Incoloy 800 exhibited refined columnar/equiaxed dendrites with chromium carbides and Fe-Ni-Ti intermetallics. Mechanical testing indicated enhanced yield strength but reduced impact toughness and marginal hardness gain in A286 welds, whereas Incoloy 800 welds maintained similar hardness to the base material. Overall, the study demonstrated utilization of fiber-coupled diode laser welding for producing butt-joints in both superalloys, supporting their potential adoption in high-temperature applications. © 2025 Taylor & Francis Group, LLC.