Influence of H2S on the Hydrogen Embrittlement Susceptibility of X80 Pipeline Steel in Hydrogen-Doped Natural Gas

This study investigated the behavior of H2S on the hydrogen embrittlement susceptibility of X80 pipeline steel in hydrogen-doped natural gas and thoroughly discussed the mechanism of its influence. The results indicated that H2S accelerated the hydrogen embrittlement of X80 steel, and the higher its content, the more severe the embrittlement of the material. Besides, when H2S gas was introduced into the hydrogen-doped natural gas, the fracture in the brittle region near the surface presented a mixture of quasi-cleavage and cleavage fracture morphologies, which exhibited typical hydrogen embrittlement characteristics. Furthermore, it was inferred from the results of mechanical properties and fracture morphology analysis that H2S competed with H2 and CH4 for adsorption sites at large-angle grain boundaries, which increased the ability of iron atoms to provide electrons to hydrogen molecules adsorbed on the steel surface and thus promoted hydrogen embrittlement.