Relationship between Crack Formation Energy and Propagation Energy in Charpy V-notch Impact Test of Two Steels

The Charpy V-notch impact test of Q245R steel and 13MnNiMoR steel were carried out at a series of temperatures by using instrumented impact test method. The relationship between the crack formation energy W_i and the crack propagation energy W_p of two steels was studied comparatively. The results show that the crack formation energy W_i of two steels not changed along with the change of temperature at the upper platform and temperature range adjacent to the transition zone on ductile-brittle transition K_V2-t curve, but the value of 13MnNiMoR steel was higher than that of Q245R steel. The ductile-brittle transition of material originated from the transition of crack propagation energy W_p, which was the key factor determining the transition from toughness to brittleness of material.