Potential Dependence of Hydrogen Embrittlement Susceptibility of Ultra High Strength Low Alloy Steel

In order to investigate the susceptibility of the ultra high strength low alloy steel to hydrogen embrittlement, a slow strain rate tensile test was carried out in boric acid-borax buffer aqueous solutions of pH 10 at the potential range from corrosion potential to hydrogen gas evolution potential, including adsorbed hydrogen potential. Experimental results revealed that the susceptibility to hydrogen embrittlement was dependent on the applied potential and increased linearly with increasing applied cathodic potential in the adsorbed hydrogen potential region. On the other hand, in the hydrogen gas evolution potential region, the susceptibility was independent of the applied potential and showed almost no variation. Based on the results obtained, these changes in susceptibility to hydrogen embrittlement with applied potential have been discussed in terms of the variation in reduction behavior of oxide films on the specimen surface.