An investigation of dynamic failure in 2.3Ni-1.3Cr-0.17C steel

The dominant micromechanisms of dynamic failure initiation in high-strength ductile steels were investigated using 2.3Ni-1.3Cr-0.17C steel. Fracture experiments were conducted in three-point bend and one-point bend configurations. The influence of loading rate on the extent of each micromechanism in the fracture-initiation process was considered. The fracture surfaces consisted of a tunneled region and shear lips. The shear lips are characterized by microvoids. The tunneled region consists of large voids and microvoids that coalesced by impingement. At high loading rates, localized molten zones are observed at the tunnel-shear lip interface. The material-rate sensitivity causes a decrease in the size of the tunneled area at higher loading rates.