Strength effect in stress corrosion cracking of high-strength steel in aqueous solution

The threshold stress intensity of stress corrosion cracking (SCC) for 40CrMo steel in 3.5% NaCl solution decreased exponentially with the increase in the yield strength sigma (s), i.e., K-ISCC=1.38X10(6) exp(-8.26x10(-3)sigma (s)). The threshold stress intensity of hydrogen-induced cracking during dynamical charging for 40CrMo steel decreased linearly with the logarithm of the concentration of diffusible hydrogen, C-0, i.e., K-IH=31.3-9.1lnC(0). This equation was also applicable to SCC of the high-strength steel in aqueous solution, where Co is a constant. The critical hydrogen enrichment concentration, C-th, necessary for SCC of high-strength steel in water decreased exponentially with the increase in the yield strength. Based on the result, the relationship between K-ISCC and sigma (s) could be deduced, i.e., K-ISCC=ak(1)exp(-k(2)sigma (s)), where a = 3RT root pi rho /2(1+upsilon)(V) over bar (H), k(1) and k(2) depended upon the compositions and microstructure of the steel as well as the test conditions.