Effects of Impurities on Environmentally Assisted Crack Growth of Solution-Annealed Austenitic Steels in Primary Water at 325°C

Abstract

Abstract Effects of impurities (Si, P, and S) in steel on environmentally assisted cracking (EAC) behavior of solution-annealed austenitic steels in pressurized water reactor (PWR) primary water at 325°C were investigated. The basic chemical composition of the steels was 12% Cr-28% Ni, simulating the grain boundary (GB) composition of irradiated Type 304 (UNS S30400) stainless steel. The EAC crack growth behavior of the steels was examined by performing trapezoidal wave cyclic loading testing on precracked specimens. Results showed that Si significantly affected the EAC by promoting intergranular cracking, with only 0.48% Si promoting almost fully intergranular cracking under trapezoidal wave loading; increasing the crack growth rate; and tending to make cracking easier in the near-surface region rather than in the center of specimens. Only transgranular cracking with relatively low crack growth rates took place in the steels without Si but doped with S and P, respectively. The stress corrosion cracking (...