Effect of cold work and slow strain rate on 321SS stress corrosion cracking in abnormal conditions of simulated PWR primary environment

Abstract

In this paper, stress corrosion cracking (SCC) behavior of 0%, 5%, 10% cold-worked (CW) 321 stainless steel (321 SS) in abnormal conditions of simulated pressurized water reactor (PWR) primary water was studied at two different slow strain rates of 4.2 × 10−6, 4.2 × 10−7. The experimental results show that with the increase of the degree of cold work, the internal grain of the sample is refined. The slip zone and deformation twins occur inside some grains. The SCC sensitivity of the strain rate of 4.2 × 10−7 S−1 is higher than the strain rate of 4.2 × 10−6 S−1. And the higher the degree of cold work, the higher the SCC sensitivity of the sample. Dynamic strain aging (DSA) occurs at 321 SS with different cold work degrees with a slow strain rate of 4.2 × 10−7 S−1. DSA makes the tensile zone near the fracture of 5% CW and 10% CW samples have higher vacancy defect density, which promotes the initiation and expansion of SCC crack. Keywords: Cold work, Slow strain rate tension, Stress corrosion cracking, Dynamic strain aging, Vacancy defect