Influence of Portevin–Le Chatelier effect on rupture mode of alloy 718 specimens

A set of tensile tests has been carried out under air environment in the temperature range (450–700 °C) in order to characterize the interactions between oxidation assisted intergranular cracking and Portevin–Le Chatelier effect. It is shown that the occurrence of jerky flow stops the intergranular damaging mechanism. The construction of a temperature versus strain rate diagram showing dynamic strain aging, intergranular fracture and PLC instabilities locations is then proposed. The surprising relation between crack initiation disappearance and PLC instabilities of type C in the temperature range explored is discussed. Finally the assumption of the occurrence of such phenomenon at the tip of a propagating crack is addressed.