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

Hydrogen embrittlement of a copper precipitation strengthened and niobium m icroalloyed HSLA 80 steel on cathodic charging in synthetic sea water has b een studied using a slow strain rate technique. The effects of strain rate and potential applied for hydrogen charging have been studied. Hydrogen mea surement at different potentials has also been carried out. A loss in ducti lity in terms of a drop in percentage elongation and percentage reduction i n 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 ha rdening effect of hydrogen charging up to -600 mV(SCE) followed by a soften ing effect has been observed. The results are discussed in the light of the existing models of hydrogen-dislocation interaction and hydrogen induced m icrovoid coalescence. MST/4405.