Effect of welding conditions on residual stress and stress corrosion cracking behavior at butt-welding joints of stainless steel pipes

Katsuyama, Jinya  ; Tobita, Toru; Ito, Hiroto*; Onizawa, Kunio 

Stress corrosion crackings (SCCs) in recirculation pipes of Type 316L stainless steel (SS) have been observed near butt-welding joints. These SCCs in Type 316L SS grow near the welding zone mainly due to high tensile residual stress by welding. In present work, scatters of welding conditions such as heat input and welding speed were measured experimentally by fabricating a series of butt-welded pipes. Residual stress distributions were measured by stress relief and X-ray diffraction methods. The effects of welding conditions on residual stress have been evaluated by parametric FEM analyses considering the variation of some welding parameters based on the experiments. The effects of welding conditions on crack growth behavior have been also evaluated by using calculated residual stress distributions. It was clearly shown that the uncertainties on welding heat input and speed have strong influences on SCC growth behavior.