Faculty Publications

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    Microbial effects on heat treated 316L weldments in marine water
    (2013) Suvarna, K.; Udupa, K.R.; Surendranathan, A.O.
    Austenitic stainless steels are susceptible to microbiologically influenced corrosion (MIC) when they are in contact with sea water. This is due to the changes in the chemistry of the environment at the metal surface because of the settlement and activities of microorganisms. The thrust of our work was in understanding the changes in the electrochemical behaviour of a type 316L stainless steel in the presence of a natural biofilm as well as the influence of metallurgical characteristics on microbial adhesion and MIC. The presence of a biofilm on material surface can influence the corrosion behaviour since the value of a given parameter such as temperature, pressure, concentration of a solute and pH at the water /substrate interface under the biofilm may be different from that in the bulk environment. The non-uniform nature of biofilm thus helps in generating heterogeneity in the environment at the surface. Thus, biofilms are known to aid in the initiation of corrosion, change the mode of corrosion or cause changes in the corrosion rate. Bacteria Arthobacter nicotinae (An) and algae Chlorella pyrenoidosa (Cp) were used for the study and bio film formed due to these showed pit initiation and increase in corrosion rate as time proceeds. 316L base metal (BM) and weld metal (WM) as received and after heat treated at 450°C for 10000 hours were studied and corrosion evaluation was done. Heat treated WM showed severe response to corrosion compared to as received WM. © (2013) Trans Tech Publications, Switzerland.
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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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    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.