Quasi-cleavage fracture planes in spheroidized A533B steel

Electron backscattered diffraction (EBSD) has been used to acquire crystal orientation information around unusual microcracks induced by tensile deformation of notched specimens of spheroidized A533B steel. This unusual fracture mode has been called quasi-cleavage and occurs at relatively low temperatures with fracture energies below that of the upper shelf. EBSD measurements on sectioned samples showed that the quasi-cleavage cracks were intragranular. A two-dimensional analysis technique was used in which EBSD measured crystal orientations were combined with secondary electron imaging to obtain the trace of the crack facet on the section plane. The measurements revealed that the observed crack facets were consistent with crack propagation along the {001} and {011} planes.