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

Abstract

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.

Effects of Different Operating Temperatures on the Tensile Properties of the Grid Plate Hardfaced with Colmonoy in a Pool Type Sodium Fast Reactor

“…Hence, the hardfaced deposit is very safe due to compressive stress [10]. Table 1 shows the process parameters for hardfacing by PTAW for lower dilution and finer microstructure so that maximum hardness of the coating can be achieved [11]. The presence of silicon creates fluidic property.…”

Measurement of the Residual Stresses and Investigation of Their Effects on a Hardfaced Grid Plate due to Thermal Cycling in a Pool Type Sodium-Cooled Fast Reactor

“…A trapezoidal annular groove to a depth of 3 mm was made by milling process to coat colmonoy. Ni based hardfacing alloy called colmonoy 5 was coated in the annular groove by Plasma Transferred Arc Welding at the welding speed of 3 mm/s for the least process-induced residual stresses with minimum dilution from the base metal into the coating so that the properties of the coating are not significantly affected [22,23]. The process-induced residual stresses should be low for better annealing results.…”