The stress corrosion cracking (SCC) susceptibility of SUS304 stainless steel cathodically precharged with hydrogen was investigated in boiling 35% MgCl2 solution at 398K.
The specimen preparation was carried out by precharging at 200A/m2 for 7.2ks in the SCC test solution after 0∼35% prestrained at 195K, and successively SCC tested by the constant loading method.
The mechanical properties of specimens precharged with hydrogen are closely related to the hydrogen-induced phase transformation. By precharging with hydrogen, especially the lattice of α'-martensite in high prestrain is expanded and activated. In this case, the crack initiation during SCC of these specimens is controlled, consequently the SCC susceptibility shows a marked decrease. On the other hand, the SCC fracture surface morphology of specimens precharged with hydrogen depends on the distribution and form of strain-induced martensite (ε, α'), which contributes considerably to the susceptible path for cracking.
It is considered from these results that the role of hydrogen dissolved in specimen during SCC has the effect of embrittlement and active dissolution to ε-and α'-martensite, respectively.