A study on fracture properties of multiphase microstructures of a CrMo steel

An investigation into the fracture properties of tempered martensite (TM) and ferrite–bainite–martensite (FBM) microstructures was carried out for a CrMo steel, with a particular focus on the role of inter-phase FBM microstructure boundaries. The fractographic investigations showed the fracture mechanism of transgranular cleavage for the FBM microstructures. The obvious presence of bright facets on broken sample surfaces was indicative of the effect of inter-phase boundaries on the cleavage fracture. The appearing of bright facet surfaces in FBM microstructures was attributed to the high concentration of ferrite/bainite and ferrite/martensite inter-phase boundaries.