Effect of microstructure on hydrogen embrittlement of various stainless steels

This work investigated the effect of microstructure on the susceptibility of 304L (metastable), 310S (stable) austenitic and 410 martensitic stainless steels (SSs) to hydrogen embrittlement (HE). Slow-displacement-rate notched tensile tests were performed at various combinations of temperature (25 and 80 °C) and environment (air and H2) to evaluate the relative HE susceptibility of these alloys. At 25 °C, the untempered 410 SS was the specimen most susceptible to HE among the investigated specimens, whereas the 310S and tempered 410 specimens exhibited low HE susceptibility. The formation of strain-induced α′-martensite in a localized region in front of the notch tip was the main cause for the high HE susceptibility of the 304L SS tested at 25 °C. In general, the HE susceptibility was reduced to various degrees for specimens tested at 80 °C. A significantly lower susceptibility to HE was observed for the 304L specimen at 80 °C due to the suppressed formation of α′-martensite in the highly strained region.