Compressive Deformation Behavior of Thick Micro-Alloyed HSLA Steel Plates at Elevated Temperatures

The hot deformation behavior of a heavy micro-alloyed high-strength low-alloy (HSLA) steel plate was studied by performing compression tests at elevated temperatures. The hot compression tests were carried out at temperatures from 923 K to 1,223 K with strain rates of 0.002 s and 1.0 s . A long plateau region appeared for the 0.002 s strain rate, and this was found to be an effect of the balancing between softening and hardening during deformation. For the 1.0 s strain rate, the flow stress gradually increased after the yield point. The temperature and the strain rate-dependent parameters, such as the strain hardening coefficient ( ), strength constant ( ), and activation energy ( ), obtained from the flow stress curves were applied to the power law of plastic deformation. The constitutive model for flow stress can be expressed as = (39.8 ln ( ) – 716.6) · for the 1.0 s strain rate and = (19.9ln ( ) – 592.3) · for the 0.002 s strain rate.