Fracture prediction of NM450TP wear-resistant steel plates during air bending using a mesoscopic heterogeneous model

Abstract

A mesoscopic finite element model considering material heterogeneity based on microstructure features was constructed to predict the fracture of NM450TP plates during air bending. The fracture morphology and crack initiation and propagation were specifically addressed from two typical planes of the viewing direction, namely, the section plane orthogonal to the bending axis and the bending (outer) convex surface under tension during bending. The results demonstrated that the model could accurately reproduce the initiation, propagation and final fracture morphology. In the section plane, strain shear bands appeared and then developed into the onset of the initial crack with an inclined angle of 45° to the convex surface. As bending developed, the crack randomly expanded towards the through-thickness direction, ascribed to the interaction between the stress mode and material heterogeneity. In the bending convex surface, the fracture morphology dramatically changed with the relative position between the bending axis and rolling directions. When the bending axis was perpendicular to the rolling direction, a serrated fracture line was formed. When the bending axis was parallel to the rolling direction, a nearly linear fracture line was finally formed along the bending axis.