Abstract
To study fracture initiation, mild steel plates, normalized or cold rolled, were notched and subjected to the tensile test at different temperatures. For the normalized specimens an abrupt or rapid change was observed in stress or COD to fracture at −130°C. A qualitative explanation was given to this transition phenomenon. The cold-rolled specimens fractured without general yielding in a ductile manner at all the testing temperatures; the fracture stress lowered with increasing strain rate, nearly independent of temperature.
