Loading-rate dependence of fracture absorption energy of low-carbon carbide-free bainitic steel

Abstract

In this letter, the fracture absorption energies of a carbide-free bainitic steel at different loading rates were investigated using three-point bending test. The results show that the crack initiation, propagation and total absorption energies of U-notched samples of the steel increase significantly with increasing the loading rate. In comparison, for pre-cracked samples, although the crack initiation energy almost does not change with loading rate, the propagation and total absorption energies remain to increase with raising the loading rate. These observations are analyzed based on the loading-rate sensitivity of strain-induced martensitic transformation and also its twofold roles in fracturing of the steel.