Effect of tensile stress on pitting damage

Yamaguchi, Yoshihito*; Kogawa, Hiroyuki  ; Naoe, Takashi   ; Futakawa, Masatoshi  

High power spallation targets for neutron sources are being developed in the world. A mercury target is being installed in the material and life science facility of J-PARC (Japan Proton Accelerator Research Complex). The mercury target is subjected to pressure waves caused by a proton beam bombardment. The pressure waves load macroscopic stresses on the target vessel and induce the cavitaion in mercury through the pressure wave propagation processes. When cavitation bubbles collapse, the localized impact damages so-called pitting damage, occur on the target vessel. The target vessel is subjected to the pitting damage and macroscopic stress at the same time. It is necessary, therefore, to evaluate the superimposed effect of macroscopic stresses the pitting damage. Pitting damage tests were carried out using a ultrasonic cavitation testing with a static tensile-stress loading unit. The results showed that the damage increased with the imposed tensile stress.