Effects of environment factors on stress corrosion cracking of austenitic stainless steels in atmospheric environments

Abstract

Effects of sensitization, relative humidity (RH), and chloride concentration on stress corrosion cracking (SCC) behaviors at low temperature in atmospheric environments were studied by using U-bend specimens of as-received (cold-worked) and sensitized Type 304 steels. NaCl and MgCl2 salts were put on the specimens, and the specimens were set in the constant temperature and humidity chamber with 40∼70% RH at 40°C for 720h. The results showed that the Type 304 steel became more susceptive to SCC when increasing humidity and chloride concentration. MgCl2 was more effective to SCC while NaCl was less effective. In the sensitized specimens, deep cracks were observed with small branches and the crack propagated through grain boundaries.