Cavitation erosion behavior of Hastelloy™ C-276 weld by laser welding

Abstract

Ni-based Hastelloy C-276 was chosen as the material of the stator and rotor cans of a nuclear main pump for its excellent resistance to corrosive environments and superior mechanical properties. In the present work, the cavitation erosion (CE) behavior of the Hastelloy C-276 thin sheet weld joint was tested. The results indicate that both the CE damages of the weld metal and the base metal initiate at grain boundaries preferentially. The solidification grain boundaries (SGBs) of the weld metal and the twin boundaries (TBs) of the base metal are more susceptible to CE. For the weld metal, due to the microstructure inhomogeneity, regions that show the highest damage intensity are located near the central line of the weld surface where the columnar dendrites interact with the nearly equiaxed dendrites. For the base metal, grains with more TBs are damaged faster compare to other grains. The surface roughness of the eroded surfaces increases with exposure time, and the surface roughness of the base metal increases faster than that of the weld metal. Overall, the resistance to CE of the weld metal is better than that of the base metal.