Influence of the Phosphorus Content on the Hydrogen Embrittlement Susceptibility of Some DP Steels Studied Using the Linearly Increasing Stress Test

The hydrogen embrittlement (HE) of some DP steels was investigated, focusing on the influence of the phosphorus (P) content. Hydrogen-induced micro-cracks and brittle fracture occurred at edges follows the HESIV and HEDE mechanisms. The increased number of ferrite related interface micro-cracks was attributed by the enhanced interface weakening effect of excess P content. Hydrogen influenced crack propagation and fracture in the inner ductile part of the specimen followed the HELP mechanism and can be promoted by a higher P content in solution in matrix. An increased P content caused more significant HE susceptibility for DP steel with less and separated martensite and less Cr, Mo microalloying.