Hydrogen embrittlement of weld metal of austenitic stainless steels

Abstract Using slow strain rate tests, the role of atomic hydrogen and hydrogen-induced martensites in hydrogen embrittlement of weld metals of type 308 and type 347L austenitic stainless steel (ASS) and type 304L plate was quantitatively studied. The results indicated that hydrogen-induced martensites formed in the three kinds of ASS when diffusible hydrogen concentration C0 exceeded 30 wppm, and the total amount of the hydrogen-induced martensites increased with increasing C0. The relative plasticity loss caused by the hydrogen-induced martensites Iδ(M) increased linearly with increasing the amount of the matensites. The plasticity loss caused by atomic hydrogen Iδ(H) for the three kinds of ASS increased with increasing C0 and reached a saturation value of 40–50% when C0>100 wppm. Iδ(H) decreased linearly with increasing the logarithm of strain rate e and was equal to zero when e =0.018–0.032 /s. The plasticity loss caused by the hydrogen-induced martensites is determined by C0 and that by atomic hydrogen is determined by the hydrogen concentration at the transient to failure C(t).