Probing intergranular mixed transgranular stress corrosion cracking under the high constant load

Stress corrosion cracking (SCC) of non-sensitized austenitic stainless steel during immersion of MgCl(2) solutions was investigated by X-ray computed tomography and scanning electron microscopy. SCC cracks propagated transgranularly at the initial stage, and switched to the IGSCC mode under the high constant load. There was no ductile dimple present on the SCC fractography, but numerous cleavage facets, slip bands and pits emerged. The cohesive zone appeared ahead of the crack tip. It is indicated that the high-load SCC also coincides with the cleavage dissolution mechanism, predominantly originating from the corrosive environment particle assisted cleavage and the obstacle induced dislocation pinning.