Stress Corrosion Cracking Susceptibility of Austenitic Stainless Steels and Nickel-based Alloy in Supercritical Water at 550 ℃/25 MPa

The stress corrosion cracking(SCC) susceptibility of austenitic stainless steels 316Ti, HR3C, TP347 and nickel-based alloy 718 in supercritical water(SCW)at 550 ℃/25 MPa was studied. Slow strain rate tests (SSRT) were used to obtain the stress-strain curves. The results show that the yield strength and tensile strength of 718 were much higher than those of the other three austenitic stainless steels while the elongation of 718 was significantly lower. Scanning electron microscopy observations of fracture surfaces reveal. that the failure mode of 316Ti and TP347 was transgranular ductile fracture, the failure mode of HR3C was both intergranular and transgranular ductile fracture and the failure mode of 718 was almost intergranular stress corrosion cracking (IGSCC).