Stress Corrosion Cracking of the Fusion Boundary for 304L/82 Dissimilar Metal Weld Joint in Simulated Primary Water

Abstract

The stress corrosion cracking behavior of the fusion boundary for 304L/82 dissimilar metal weld joint was studied in simulated primary water. Analytical electron microscopy was utilized to characterize the cracking features. Results demonstrated that the heat-affected zone in Type 304L has a higher stress corrosion cracking susceptibility and the crack propagated from weld region to Type 304L heat-affected zone in the form of intergranular cracking. The electron back-scattered diffraction and transmission electron microscopy–electron dispersive x-ray spectroscopy results showed that the intergranular cracking in the heat-affected zone of Type 304L was caused by the high residual strain rather than grain boundary Cr-depletion in front of the crack tip. The suppressed crack growth rate in hydrogenated water was attributed to the stable Cr-rich oxide formed at crack tip.