Influence of dynamic strain ageing on ductile fracture of a C-Mn steel

Abstract

International audienceDuctile fracture of a C-Mn steel was characterised by tensile tests performed in a largetemperature range (from 20 to 350°C) on round notched specimens. The experimentalresults revealed a sharp drop of fracture strain around 250°C. This corresponds to thedomain of dynamic strain ageing (DSA) occurrence. The Portevin-Le Chatelier (PLC) effect,which is the most classical effect of DSA, was modelled on round notched specimens with amechanical behaviour model including the strain ageing effect. Local approach to fracturewas applied to predict the ductile fracture using the Rice and Tracey criterion. Thepredictions are rather close to the experimental results for the low and high temperatures. Inthe DSA domain, the approach predicts a decrease of the fracture strain but with a lowermagnitude than the experimental one. Therefore, DSA has an effect on mechanical behaviour but also on fracture mechanisms. Consequently, the fracture criterion has to bemodified in the presence of DSA