Effect of ultrasonic impact peening on stress corrosion cracking resistance of austenitic stainless-steel welds for nuclear canister applications

In nuclear applications, the utilization of austenitic-based stainless steel (ASS) components is an ideal material choice for storing spent nuclear fuels in dry storage canisters (DSC). However, due to the chloride rich environments in which they operate, failure in the form of stress corrosion cracking (SCC) frequently occurs. The following study assesses the efficacy of ultrasonic impact peening (UIP) on SCC susceptibility of gas tungsten arc welded (GTAW) stainless steel (SS) components, with an aim to control the SCC failure. The UIP induces residual compressive stresses (RCS) and a severely plastically deformed (SPD) layer containing nanograins on the surface. The superior SCC resistance of UIP'ed specimens is due to the synergistic effect of grain refinement and RCS. The underlying mechanisms for these findings were elucidated based on the modification of microstructural features and mechanical properties. These findings demonstrate that UIP is a potential technique for DSC application to mitigate the SCC susceptibility of ASS weld joints.