Correlation between the microstructure and hydrogen embrittlement resistance in a precipitation-hardened martensitic stainless steel

Abstract Custom 465 precipitation-hardened stainless steel was subjected to various thermal treatments and then evaluated using tensile testing with a slow strain rate after electrochemical hydrogen charging. The investigation revealed that cryogenically-treated and thermally-aged (593 ℃) specimens exhibited superior resistance to hydrogen embrittlement. Prolonging the aging time reduced the hydrogen susceptibility, which was primarily attributed to the increased stability of reversed austenite caused by the dissolution and transformation of η-Ni3Ti. Stress concentration relaxation due to the absence or ripening of η-Ni3Ti further reduced the hydrogen susceptibility. Additionally, hydrogen-induced subcritical cracks initiated on the sample surface governed the fracture behavior.