Serrated Flow Behavior of 11Cr3W3Co Steel during Tension at Different Temperatures

Tensile test was carried out on 11Cr3W3Co steel in standard heat treatment state at different strain rates (5×10^-5-2×10^-4 s^-1) and different temperatures(25-700℃), and the serrated flow behavior at different temperature of the steel was analyzed. The results indicate that the normal Portevin Le Chatelier (PLC) effect with sawtooth formation activation energy of 124 kJ·mol^-1 occurred at intermediate temperature of 285-325℃, serrated flow behavior was mainly caused by the interaction between substitutional solute chromium atoms and moving dislocations; regarding the abnormal PLC effect appeared at temperatures of 325-365℃, one possible reason is that the diffusion ability of solute atoms was strong with the increase of tensile temperature so that solute atmosphere was unstable to be present, resulting in a weaken of dynamic strain aging (DSA), another possible reason is that precipitates become sink positions due to the increase of temperature, resulting in a disappearance of serrated flow; at high temperature, rapid reduce in strength and rapid increase in plasticity imply that dynamic recovery plays a major role during the plastic deformation.