Browsing by Author "Devakumaran, K."

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    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.
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    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.
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    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.
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    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.
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    Welding of Dissimilar A5754-A5083 and A6061- A6082 Aluminium Alloys for Automotive Applications
    (National Institute of Technology Karnataka, Surathkal, 2021) Rajeshkumar, R.; Banerjee, Kumkum.; Devakumaran, K.
    In the present study, dissimilar aluminium alloy combinations A6061 T6-A6082 T6 and A5754 H111-A5083 H111 were welded using the cold metal transfer (CMT), tungsten inert gas (TIG) welding and friction stir welding (FSW) processes. Each dissimilar combination was welded by two different fillers, such as ER4043 and ER5356, in CMT and TIG. Since FSW is a solid-state welding process, no filler materials were used. The miniature tensile samples were extracted from the interface regions of the TIG and CMT welded joints and the stir zone (SZ) of the FSWed joint. The TIG and CMT welded alloys' individual interface microstructure has been correlated with mechanical properties. The SZ of FSWed parts is of prime importance because this zone primarily decides the resulting property of the welded joint. Therefore, the microstructural features and mechanical properties of the SZ in the FSWed joints have been investigated in detail. The tensile properties of the overall weld region samples have been determined using macro-tensile testing samples. The dissimilar A6061-T6 and A6082-T6 joints welded by CMT and TIG welding processes using two different fillers (ER5356 and ER4043) exhibited higher strength in the A6082 interface in comparison to the A6061 interface. When the dissimilar A5754 and A5083 alloys were welded by CMT and TIG welding processes using two different fillers (ER5356 and ER4043) fillers, the interface region of the A5083 side exhibited higher strength than the interface region of the A5754. In the FSWed joints, the refined grain structure in SZ increased the hardness and strength. The overall joint tensile properties of the dissimilar joints are essential for identifying a suitable welding process to join A6061-A6082 and A5754-A5083 dissimilar alloys. Among the A6061-A6082 dissimilar joints, the CMT joint produced by ER5356 filler and the FSW joint exhibited higher tensile properties than the other joints. The tensile properties of the A6061-A6082 dissimilar CMT joint produced by ER5356 filler and the FSW joint are nearly the same. However, the FSW process does not use any shielding gas, filler materials, and the surface preparation is also not critical for the process. These factors can play a vital role to reduce the cost of welding effectively. Also, the FSW process is environment friendly, due to the absence of fumes and shielding gases. In the case of A5754-A5083 dissimilar joints, the FSW joint shows higher tensile properties than the other joints. Therefore, the FSW process can be recommended as the preferable joining method among all the investigated processes.