A Study of redistribution of residual stress and hardness due to welding and surface-machining at girth welded joint

Mochizuki, Masahito*; Katsuyama, Jinya  ; Ihara, Ryohei*; Mori, Hiroaki*; Mikami, Yoshiki*; Onizawa, Kunio 

Stress corrosion cracking near the welded zone of core internals and recirculation piping has been observed at the surface where tensile residual stress exists due to welding and/or surface machining. The tensile residual stress in the inner surface of the pipe is caused by welding and surface machining. In this study, Vickers hardness and residual stress distributions at the inner surface of butt-weld joint with surface-machining before and after welding were experimentally evaluated. Welding simulation has been performed to study the distribution and the occurrence mechanism of tensile residual stress. It was shown that residual stress and hardness distributions by welding after surface machining depended on the welding condition and that the effect of surface machining disappeared. Residual stress distributions due to surface-finishing after welding were also found to depend on surface-machining condition but the region was limited to a thin area of surface hardened layer.