Stress Corrosion Cracking Behavior of the Fe-base Shape Memory Alloy in High Temperature Water
Shinobu Matsushima, Shigeo Ohashi, Tadao Ishihara
The effects of dissolved oxygen (DO), test temperature and strain rate on the stress corrosion cracking (SCC) behavior of a Fe-base shape memory alloy in high temperature pure water were determined. The tests were conducted by using slow strain rate test machine in water of 383K-563K. The shape memory alloy was found to have two types of the SCC. The one type of cracking occurred above 473K. The SCC susceptibility increased with temperature and dissolved oxygen promoted the SCC as well as the case of austenitic AISI 304 stainless steel. The other type of cracking was observed at the temperatures lower than 423K. Decreasing the test temperature and the oxygen concentration increased the SCC susceptibility. Considering from the transformation temperature of the tested alloy, the mechanism of cracking in the low temperature region is inferred to be hydrogen embrittlement.