11 Crystallographic Analysis of Hydrogen-Related Fracture in Medium Carbon Martensitic Steel

This study investigated crystallographic features of hydrogen-related fracture behavior in a medium carbon steel. With decrease of tempering temperature, elongation of the hydrogen-charged specimen decreased, and the fracture mode changed from transgranular fracture to intergranular fracture at prior austenite grain boundary. The orientation analysis using electron backscatter diffraction revealed that the hydrogen-related fracture surfaces for both transgranular fracture and intergranular fracture were irregular and consisted of small facets parallel to {011} planes of martensite. As the {011} planes are slip planes of martensite, it can be concluded that the hydrogen-related fracture was accompanied by local plastic deformation.