SCC Behavior of Austenitic Stainless Steel AL-6XN in SCW Environment

Stress corrosion cracking (SCC) susceptibilities of superaustenitic stainless steel AL-6XN in supercritical water (SCW) at 550 ℃/25 MPa and 650 ℃/25 MPa were evaluated, and the effects of irradiation on its susceptibility to SCC in SCW at 550 ℃/25 MPa was also evaluated. Slow strain rate tests (SSRT) were used to obtain the stress-strain curves and scanning electron microscopy (SEM) was used to observe the fracture surfaces. The results show that the mechanical strength and elongation of AL-6XN have no obvious change after being irradiated, and the susceptibility to SCC was low. The susceptibility to SCC increased obviously when the temperature was up to 650 ℃, which means the susceptibility of AL-6XN is high. It was also observed that AL-6XN showed dynamic strain aging (DSA) phenomenon in SCW at 550 ℃/25 MPa.