Delamination Fracture in a Medium-Carbon Low-Alloy Steel Subjected to Tempforming

Abstract

The effect of tempforming on strength and fracture toughness of a 0.4%C-2%Si-1%Cr- 1%Mo-VNb steel was examined. Tempering at a temperature of 600°C followed by plate rolling at the same temperature results in the formation of lamellar structure with a spacing of 72 nm between longitudinal boundaries and a lattice dislocation density of ~1015 m−2 that enhances fracture toughness in normal direction of tempformed plate. The increase in the absorbed impact energy is attributed to delamination, which occurs in plains intersecting the propagation path of main crack that blunts crack tip.