Analytical study of the relaxation of welding residual stress by excessive loading for austenitic stainless steel piping welds

Katsuyama, Jinya  ; Onizawa, Kunio 

Welding residual stress is one of the most important factors of stress corrosion cracking (SCC) for austenitic stainless steel in pressure boundary piping. The effect of excessive loading, such as an earthquake, on the residual stress is evaluated by three-dimensional analyses based on finite element method (FEM). After conducting welding residual stress simulation, several loading patterns of prescribed displacements for piping butt-welds have been applied in the axial direction by varying loading level and pattern. Bending moments have been also applied considering the start-finish point of girth welding by varying the loading direction and bending angle. The analyses indicated that higher loading to axial and bending stresses caused higher relaxation of welding residual stress even if the applied stress level is below general yield point. We concluded that the SCC growth rate could decrease as the amount of prescribed displacement increased.