Pitting Damage and Residual Stress Induced by Cavitation Erosion on Mercury Target Vessel

Abstract

Cavitation damage that might be imposed on the mercury target vessel of a pulsed spallation neutron source was evaluated from the standpoints of residual stress and plastic deformation. The residual stress distribution and plastic region of a type-316L austenitic plate, called 316SS, and that with 20% cold rolling, called 316CW, were measured using an X-ray diffraction technique. As a result of the peak width distribution in each specimen with the cavitation damage, the plastic region in the 316SS was deeper than that in the 316CW. In addition, the internal compressive residual stress of the 316SS was higher than that of the 316CW. The distributions of plastic strain and residual stress affect the crack propagation from the bottom of the pits. Taking into account the energy balance in each specimen subjected to the cavitation damage based on the distributions of plastic strain and residual stress, the difference in the fatigue limit degradation between 316SS and 316CW was explained.