Stress corrosion cracking of Al-added mild steel

Abstract

Stress corrosion cracking (SCC) experiments under constant load were conducted in boiling 55 % Ca(NO 3) 2 solution using Al-added low carbon steel. The as-normalized and decarburized specimens fractured intergranularly within 2 to 4 h, when held under constant loads of 0.44 and 0.90 of ultimate tensile strength (UTS), respectively. The precipitation of fine carbide and the segregation of P are probably responsible for the SCC of the decarburized specimen. An appreciable plastic deformation is a necessary condition for the occurrence of intergranular SCC. SEM fractography suggests that it is neither hydrogen-induced embrittlement (HE) nor stress-induced cracking, but anodic SCC (strain-induced SCC) which is involved in the SCC of mild steel in Ca(NO 3) 2 solution.