Hydrogen Embrittlement of Mild Steel Charged Cathodically with Hydrogen : Effect of Dissolved Hydrogen and Hydrogen Damage on Elongation of Mild Steel

In order to study the effects of dissolved hydrogen atoms and hydrogen damage on elongation of mild steel in relation to the susceptibility of iron and steel to hydrogen embrittlement, tensile tests were carried out immediately after cathodic hydrogen charging and after degassing of hydrogen at room temperature. Because cathodic hydrogen charging caused internal damage, such as microcracks (blisters) and plastic deformation owing to hydrogen precipitation, the influence of the dissolved hydrogen on the elongation was distinguished from that of hydrogen damage. The dissolved hydrogen and hydrogen damage were found to cause reversible and irreversible reductions in elongation, respectively.