Ductile to brittle fracture transition of a plain carbon steel and its thermal activation model

An investigation has been made on the ductile to brittle fracture transition of a C-Mn steel due to variation of loading rates at constant temperatures. The transition takes place with increasing loading rate, which is similar to that caused by decreasing temperature. An equation has been derived from the thermal activation analysis which correlates the fracture toughness with temperature and loading rate. A model of fracture transition has been proposed from the thermal activation movement of atoms.