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In this paper, plasma transfer arc welding using hard faced material Colmonoy which is deposited on a annular groove of a circular grid plate made up of SS 304 was studied. Hard face deposition made by Plasma Transferred Arc Welding (PTAW) on a annular groove of a grid plate at relatively high temperature, generates residual stresses due to differential shrinkage of the molten deposit, process-induced thermal gradients and difference in coefficients of thermal expansion between the colmonoy deposit and base material SS 304. However, the magnitude and distribution of the residual stresses vary depending on the heat input, deposition process, and the geometry of the component. Finite element analysis of residual stress is performed with commercial FEA package of ANSYS 12.0 which includes moving heat source, material deposit, temperature dependent material properties, metal plasticity and elasticity. Coupled thermo-mechanical analysis is done for welding simulation and the element birth and death technique is employed for simulation of filler metal deposition. Finally residual stress is evaluated so that annealing is performed accordingly to relieve residual stresses in order to carry out fracture analyses thereafter.

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Colmonoy is a nickel based alloy hardfaced with SS-316 used in Prototype Fast Breeder Reactors (PFBR) to avoid self-welding and galling between nuclear reactor and grid plate. Colmonoy is coated on the base metal –SS 316 by Plasma transfer arc welding. Due to thermal cycling that exist in reactors de-bonding between colmonoy and base metal occurs which may lead to catastrophic failure of the Prototype fast breeder reactor. Hence, estimation of the fatigue life period of hardfaced colmonoy is mandatory. Before that, finding optimum parameters which influences fusion, weld strength, composition and dilution are mandatory. In order to evaluate the dilution characteristics with respect to welding speed, different specimens were prepared by holding other parameters constant. Prepared specimens were tested for hardness, microstructure and dilution to locate the difference between each specimen. Comparative studies were carried out on the specimen and their parameters like travelling speed, microscopic structure, Hardness and dilution percentage were tabulated. Based on the tabulated results, the best specimen is chosen with respect to its individual parameters.