1993 Volume 33 Issue 11 Pages 1190-1195
Sulfide stress cracking (SSC) of low strength steels are often thought as being related to non-metallic inclusions. However, effects of intrinsic metallurgical factors such as chemical composition and micro structure have not yet been clarified. In this paper, effects of strengthening due to grain refining, precipitation, solid solution and dislocation were studied using tensile type SSC tests. Threshold stress (σth) is in proportion to intragrain hardness irrespective of strengthening mechanism and grain size. Further analysis shows that σth is related to σo defined in the Hall-Petch relationship. The ratio of σth to yield strength therefore increases with an increase in grain size, which is contrary to the case of high strength steel. The difference originates from the fact that SSC of low strength steels is transgranular whereas SSC of high strength steel contains integranular fractures.