Characterizing microstructural changes due to hydrogen embrittlement: Predicting mechanical properties according to hydrogen amount

To prevent the occurrence of severe industrial accidents caused by the hydrogen embrittlement (HE) of austenitic stainless steel, the mechanism of HE based on deformation behavior is identified, and a model equation for predicting the mechanical properties according to hydrogen amount is developed. The mechanical properties included with various amounts of hydrogen are evaluated via a slow strain rate test. Whereas the hydrogen trapping sites remain unchanged regardless of the hydrogen amount, the following vary: the microstructural characterizations formed by HE on the fracture surface, the work-hardening rate behavior with strain-induced martensite, and the phase fraction after fracture. Depending on the amount of hydrogen, either both ductility and brittleness or only brittleness may be observed. Based on these characteristics, the effect of hydrogen on deformation behavior is confirmed. By confirming the two effects of hydrogen on the deformation behavior, the phase fraction after fracture, elongation, and elongation loss are predicted according to the mechanical properties predicted according to hydrogen amount.