Hydrogen embrittlement of an HSLA 80 steel in sea water under cathodic charging conditions

Hydrogen embrittlement of a copper precipitation strengthened and niobium microalloyed HSLA 80 steel on cathodic charging in synthetic sea water has been studied using a slow strain rate technique. The effects of strain rate and potential applied for hydrogen charging have been studied. Hydrogen measurement at different potentials has also been carried out. A loss in ductility in terms of a drop in percentage elongation and percentage reduction in area has been observed, the effect being prominent at potentials beyond -800 mV(SCE). Fractography by SEM shows a dominance of microvoid coalescence with increasing quasicleavage features at higher negative potentials. A hardening effect of hydrogen charging up to -600 mV(SCE) followed by a softening effect has been observed. The results are discussed in the light of the existing models of hydrogen-dislocation interaction and hydrogen induced microvoid coalescence. MST/4405.