Strain rate and temperature effects on the critical strain for Portevin-Le Chatelier effect

A model was proposed to investigate the critical condition of Portevin-Le Chatelier (PLC) effect in the current paper. Hahner's limitation of the additional activation energy under completely aged condition for the existence of PLC regime was extended to a more general case, which allowed to simultaneously account for the effects of strain hardening rate and the dynamic strain aging (DSA) exponent. The dependences of the critical strain on the strain rate and temperature were also derived based on the current model. The strain rate dependent stress predicted by the current model was similar to that by Jiang's model, but with less model parameters. The predictions of critical strain evolution with strain rate and temperature were compared with experimental data published in literature. The good agreement between these results indicated that the current model can well capture the critical strain in a wide range of strain rates and temperatures.