On the correlation between the stress state of deformation and fracture behaviour in an extra-deep drawing low carbon steel

Abstract

With the aid of a scanning electron microscope, the fracture behaviour of an indigenously produced Al killed, extra-deep drawing, low C steel was studied for varying degrees of bi-axial (tensile) deformation. Using the features present on the fracture surface as indicators, for the first time a meaningful correlation could be established between the stress state and ductility. These results provided confirmatory evidence for the conclusions reached from some formability studies (reported elsewhere), apart from adding useful complementary information. The inferior ductility of one of the six heats used in the study--in spite of its excellent texture, a favourable grain size and a high average plastic strain ratio--could be traced to the detrimental alignment along the rolling direction of sulphide stringers and other inclusions. Graphs, photomicrographs.