Effect of Ni content on hydrogen embrittlement of conventional Ni-based alloys

Hydrogen has been expected as use of carbon-neutral fuel, therefore, hydrogen gas turbines and hydrogen gas combustion engines are attracting attention. Metallic materials including Ni-based alloys, are known to be embrittled when it’s exposed to hydrogen environment. Then the hydrogen embrittlement behaviour of conventional Ni-based alloys containing 0~50 mass% Fe, which are either solid solution strengthening type alloys or precipitation strengthening type alloys, are investigated hydrogen embrittlement by using slow strain rate technique under cathodic hydrogen charging condition at room temperature. Most alloys have affected by hydrogen charging, and the alloys with higher tensile strength occurred greater a hydrogen embrittlement. The alloys in a range of 30~100 mass% Ni contents occurred greater hydrogen embrittlement as a higher amount of Ni contents, however, the hydrogen embrittlement of the solid solution strengthening type is lower than that of the precipitation strengthening type in similar Ni contents. It is suggested that the precipitations affect the hydrogen embrittlement at room temperature. As an observation of fracture surface, intergranular fractures embrittled by hydrogen were dominantly shown in all alloys. The effect of hydrogen at high temperature will be also discussed about some alloys.