Fracture surface topography analysis of the hydrogen-related fracture propagation process in martensitic steel

摘要

The hydrogen-related fracture propagation process in martensitic steel was investigated through crystallographic orientation and fracture surface topography analyses. The hydrogen-related fracture surface consisted of three typical surfaces, namely smooth surfaces, surfaces with serrated markings, and surfaces with dimples. Crystallographic orientation analysis suggested that the smooth surface was generated by intergranular fracture at prior austenite grain boundaries, and the surface with serrated markings originated from quasi-cleavage fracture propagated along planes. According to the reconstructed fracture propagation process by fracture surface topography analysis, the intergranular fracture at prior austenite grain boundaries initiated and propagated suddenly at the early stages of fracture. The quasi-cleavage fracture along planes then gradually propagated within the prior austenite grains. At the final stages of fracture, ductile fracture accompanied by dimples occurred around the edge of the specimen. The results clearly indicated that the fracture propagation path changed with the proceeding fracture from the prior austenite grain boundaries to along planes within the prior austenite grains.