Susceptibility of Nickel Based Alloy of Dissimilar Metal Butt Welds

To evaluate the PWSCC susceptibility of nickel based alloy of dissimilar metal butt welds (welding cast stainless steel and alloy 600 using 82and 132 alloys) using at nuclear power plants, constant load tests for crack growth rate estimation of initiation stage and slow strain rate tests for PWSCC susceptibility and activation energy estimation were executed using dissimilar metal butt welds specimen in simulated PWR primary water condition. No clear differences of activation energy and crack growth rate of initiation stage were observed between 82 and 132 alloys. Higher PWSCC susceptibility was observed in 132 alloy than 82 alloy. Crack growth rates of initiation stage of dissimilar metal butt welds were several times lower than that of pure 82 or 132 welds. This might be the mixture effects of dissimilar metals at welds. Changed welds composition is not considered bad effects for PWSCC crack growth rate of initiation stage. From activation energy and crack growth rate of initiation stage obtained in this study, crack depth evaluation of 290°Cdissimilar metal butt welds part was executed. As a result , it was considered that 290°Cdissimilar metal butt welds part was still under initiation stage.