Effect of hydrogen on notch tensile strength of high strength steel

Hydrogen embrittlement susceptibility of a high strength steel SCM 435 was investigated by means of slow strain rate tests. It is shown that the SCM 435 steel has high susceptibility to hydrogen embritdement when quenched and tempered to a tensile strength of 1450 MPa. The notch tensile strength of hydrogen-precharged specimens is lower than that of the uncharged specimen, and it decreases in a power law manner with the increase of diffusible hydrogen content. Results on notched specimens with different stress concentration factors indicate that hydrogen-induced fracture of the steel is dependent on the peak value of the locally accumulated hydrogen concentration and the peak value of the maximum principal stress.