Effect of dissolved oxygen concentration on stress corrosion cracking behavior of pre-corroded X100 steel base metal and the welded joint in wet-dry cycle conditions

The effects of different dissolved oxygen (DO) concentrations on the stress corrosion cracking (SCC) of pre-corroded X100 steel base metal (BM) and welded joint under wet-dry cycle conditions were investigated by slow strain rate and electrochemical tests. Studies have shown that changing the DO concentration in the solution has a significant effect on the SCC susceptibility of X100 steel. With increasing DO concentration, the SCC susceptibility of X100 steel increases initially and then decreases. This is because the increased DO concentration causes increased protection of corrosion product layers, which reduces the dissolution rate of the crack tip anode, thereby slowing the crack growth rate. In the wet-dry cycle environment, the SCC mechanism of the X100 steel BM and the welded joint is the anodic dissolution mechanism. At the same DO concentration, the welded joint exhibits a higher SCC susceptibility than BM due to changes in the material microstructure caused by the welding process and residual stress.