Effect of Hydrogen Gas Pressure on the Mechanical Properties of Low Alloy Steel for Hydrogen Pressure Vessels

To provide engineering data useful in design, manufacture and operation of hydrogen storage vessels in hydrogen refueling stations, fatigue test machine equipped with high-pressure hydrogen autoclave was introduced. The effect of steel’s strength level, temperature effect, fracture toughness and pressure effect were evaluated in gaseous hydrogen environment. When steel’s strength level exceeds around 930MPa to 1000MPa, the elongation and notch tensile properties deleteriously degraded. The elongation reduction by the effect of hydrogen increased with lowering the temperature. The same sensitivity to temperature on crack growth behavior was observed. However, it was shown that the gaseous hydrogen environment only affect the slow stable crack growth but did not affect the critical flaw growth of the steel at low temperature, i.e. fast fracture. The pressure dependence of notch tensile strength ranging from 0.1MPa to 75MPa hydrogen pressure shows approximately 1/2 power dependence.