Stress corrosion cracking (SCC) in recirculation pipes made of low carbon austenitic stainless steel (Type 316L) has been observed near butt-welding joints. The recent SCC grows near the welding zone mainly due to high tensile residual stress by welding since the effect of the other contributing factors of material and environment decreases due to the countermeasures. Therefore, the residual stress analysis due to welding of austenitic stainless piping is important and has been already conducted by many researchers. In present work, scatters of welding conditions such as heat input and welding speed were measured experimentally by producing a series of butt-weld specimens of Type 316L pipes. Distribution and its scattering of residual stress were also measured by non-destructive and destructive methods. The effects of welding conditions on residual stress have been evaluated by parametric FEM analyses considering the variation of some parameters based on the welding experiments. The effects of welding conditions on crack growth behavior have been also evaluated by SCC growth simulations using calculated residual stress distributions and a procedure in the fitness-for-service code. Welding parameters such as heat input and welding speed have a strong influence on crack growth rate since residual stress is also affected by scatter of these welding parameters.
A Fatigue Crack Growth Prediction Model with Load Interaction Effects Using Crack Closure Concept, Xiaohua CHENG, Kentaro YAMADA
