Influence of Welding Speed over Dilution for Circular Grid Plate Hardfaced with Colmonoy-5

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.