Hydrogen embrittlement of weld metal of austenitic stainless steels

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 C 0 exceeded 30 wppm, and the total amount of the hydrogen-induced martensites increased with increasing C 0. The relative plasticity loss caused by the hydrogen-induced martensites I δ ( M) increased linearly with increasing the amount of the matensites. The plasticity loss caused by atomic hydrogen I δ ( H) for the three kinds of ASS increased with increasing C 0 and reached a saturation value of 40–50% when C 0>100 wppm. I δ ( H) decreased linearly with increasing the logarithm of strain rate ε ̇ and was equal to zero when ε ̇ =0.018–0.032 /s. The plasticity loss caused by the hydrogen-induced martensites is determined by C 0 and that by atomic hydrogen is determined by the hydrogen concentration at the transient to failure C( t).