Characterization and the improved Arrhenius model of 0Cr11Ni2MoVNb steel during hot deformation process

Abstract

True stress versus true strain curves of 0Cr11Ni2MoVNb alloy steel were obtained from isothermal compression tests on Gleeble-1500 tester over a wide temperature range from 1223K to 1433K and a strain rate range from 0.01s-1 to 10s-1. Considering the compensation of strain, the improved Arrhenius model based on Zener-Holloman parameter was evaluated by regression analysis and modified by optimizing parameters of strain hardening exponent as well as the deformation activation energy with a method of five-order polynomial fitting. Then constitutive equation of the flow stress was verified by comparing both the correlation coefficient R and the average absolute relative error (AARE). The main result shows that: (1) the deformation activation energy is insensitive to strain rate under a lower temperature range from 1223K to 1373K; (2) maximum values of the deformation activation energy under various strain degree are concentrated with the temperature over 1373K and the strain rate nearby 0.1s-1. (3) the improved Arrhenius model has a low value level of its parameters R(<0.977%) and AARE (<5.031%), which has a good agreement with the experimental values to predict the flow stress at different temperatures and strain rates.