Effects of loading mode and temperature on stress corrosion cracking growth behavior of strain-hardened 316L stainless steels in oxygenated pure water

The stress corrosion cracking (SCC) growth rates of strain-hardened 316L stainless steels with two yield strengths were measured in oxygenated high purity water at various temperatures and under various trapezoidal loading modes at a stress intensity factor K(or Kmax) of 15MPa.m0.5. An alternating current potential drop (ACPD) technique was used to monitor the crack growth kinetics throughout the test. The crack growth rate (CGR) is moderately enhanced by employing periodic unloading-reloading during the trapezoidal wave loading. Crack growth is thermally activated in the temperature range of 200oC-288oC. Two sets of CGR data show that the apparent activation energy changes with the temperature range. The effect of temperature on CGR could be also related to the material properties such as yield strength. The present results on the thermally activated SCC growth behavior were analyzed based on the deformation-oxidation mechanism that considers multiple subprocesses with different apparent activation energies. (author)