抄録
The environmentally assisted cracking (EAC) behavior of four austenitic steels in high temperature water environments was investigated in order to understand the role of grain boundary microchemistry in irradiation assisted stress corrosion cracking (IASCC) in boiling water reactors (BWR) and pressurized water reactors (PWR) environments. The chemical composition of the materials used was 12Cr-28Ni doped with Si, P or S impurities, to simulate the grain boundaries of highly irradiated 304 stainless steel. The steel was tested using fracture mechanics on compact tension specimens with trapezoidal wave loading. Results showed that, in simulated BWR water at 288℃, the addition of S and sensitization by a thermal treatment raised the EAC susceptibility, whereas the addition of Si or P had no apparent effect. For PWR primary water at 325℃, dissolved H_2 in the water had a significant effect on cracking. Lower H_2 content resulted in a lower EAC crack growth rate. Thermal sensitization treatment reduced the EAC susceptibility in hydrogenated PWR primary water but had no significant effect in the water without H_2.
