Effect of prestrain on fracture toughness of HSLA steels

The effect of tensile prestraining on the ductile fracture behaviour of two varieties of Cu-strengthened HSLA steels has been studied. It was observed that for both the HSLA steels the fracture toughness, JC, remained invarient up to 2% prestrain, beyond which it decreased deleteriously. The nature of variation of fracture toughness with prestrain has been explained in terms of variation of the tensile flow properties of the steels with prestrain. A model correlating fracture toughness and the tensile flow properties has been proposed and it is demonstrated that the predictions of the model matched closely with the experimental observations.