Synergistic effects of local strain-hardening and dissolved oxygen on stress corrosion cracking of 316NG weld heat-affected zones in simulated BWR environments

Stress corrosion cracking growth during long-term test in high temperature water was monitored in two 316NG weld heat-affected zones representing highly hardened and medially hardened regions. Cracking near the weld fusion line exhibited both macroscopic bifurcation and extensive microscopic branching, which was faster than that in the medially hardened region where crack kinking was observed. There is an interaction between material hardening and dissolved oxygen on crack growth. The effect of a single overloading on crack growth in 316NG heat-affected zones is less significant than that in a cold worked 316NG stainless steel.