Hydrogen embrittlement behaviour of SA508Gr.1 steels with different microstructures

Abstract

Microstructure of SA508Gr.1 modified by intercritical heat treatment(IHT) processes and pre-strain. The double-stage IHT achieves grain refinement and generates a higher proportion of bainite. The results reveal a decrease in Hydrogen embrittlement (HE) sensitivity with increasing pre-strain. The specimens treated with double-stage IHT exhibit lower HE sensitivity compared to those treated with single-stage IHT. The effect of hydrogen on fracture morphology are verified by analyzing dislocations and grain boundaries(GBs). The combined effects arising from the interaction between hydrogen and microstructures induced by different pre-strain exert a significant influence on yield strength (YS) and dislocation density. At 0 % and 3 % pre-strain, hydrogen has been observed to promote dislocation emission, which in turn leads to a significant increase in the dislocation density within the grains, resulting in an elevated YS.