Combined impact of elastic stress, prestrain and electrochemical charging on the hydrogen-induced cracking of high-strength steel

Abstract

The elastic stress, prestrain and electrochemical hydrogen charging were controlled separately using a stress ring to investigate their roles in the initiation of hydrogen-induced cracks. The brittle features of hydrogen charging-induced damages, i.e., a mixture of quasi-cleavage and intergranular cracks, on the fracture surface were confirmed for a high-strength steel, made possible by applying degassing and tension-to-fracture to the hydrogen-charged specimens. The hydrogen charging-induced cracks eliminated the ductility of material, leading to premature fracture before the yield point in subsequent tensile tests. The strong dependence of hydrogen-induced cracking sensitivity on hydrogen concentration and hydrogen charging time was observed. X-ray microtomography and tensile tests were also utilized to investigate the effect of inclusions on crack formation. This study contributes to the understanding of the combined effects of residual stress and hydrogen on the cracking of deformed steel plates.