23 Mechanical Properties of X70 Steel in Gaseous Hydrogen

The present study deals with an assessment of the hydrogen embrittlement(HE) susceptibility of a high strength steel grade API 5L X 70. Tensile properties measured for HE susceptibility at 10 MPa gas pressure and notch tensile test were carried out on room temperature. The various hydrogen contents for API 5L X70 steel were charged at 10MPa gas pressure. The fracture surfaces were changed from dimple type to quasi-cleavage type with hydrogen content. And external cracks were observed just only at 100% hydrogen content.