Influence of strain rate and temperature on tensile stress-strain and work hardening behaviour of 9Cr-1Mo ferritic steel

True stress (sigma)-true plastic strain (epsilon) behaviour examined in the framework of various flow relationships for wide range of temperatures (300-873 K) and strain rates (6.33 x 10(-5) to 6.33 x 10(-3) s(-1)) suggested that a combination of Ludwigson and Hollomon equations describes sigma-epsilon behaviour most accurately in 9Cr-1Mo steel. The variations of instantaneous work hardening rate (theta = d sigma/d epsilon) and theta sigma with stress indicated two-stage behaviour characterised by a rapid decrease at low stresses (transient stage) followed by a gradual decrease at high stresses (stage-Ill). The variations of work hardening parameters and work hardening rate in terms of theta vs. sigma and theta sigma vs. sigma with respect to strain rate and temperature exhibited three distinct temperature regimes, sigma-epsilon, work hardening parameters along with theta-sigma and theta sigma-sigma exhibited signatures of dynamic strain ageing at intermediate temperatures. Rapid decrease in flow stress and work hardening parameters and rapid shift in theta-sigma and theta sigma-sigma towards low stresses with decrease in strain rate and increase in temperature indicated dominance of dynamic recovery at high temperatures. (C) 2012 Elsevier B.V. All rights reserved.