A modified Johnson Cook model for elevated temperature flow behavior of T24 steel

The isothermal hot compression tests were carried out on Gleeble-3500 thermo mechanical simulator in the temperature range of 1323-1473 K and strain rates of 0.01 s−1, 0.1 s−1, 1 s−1 and 10 s−1. Based on the experimental results, a modified Johnson Cook model is proposed to describe the flow behavior of T24 steel. The modified model considers not only the yield and strain hardening portion of the original model but also the coupled effects of strain and temperature, and of strain rate and temperature on the flow behaviors. The high temperature deformation behavior of T24 steel was characterized based on the analysis of the stress-strain curves. The results showed that the flow stress predicted by the proposed model agrees well with the experimental stress, which validates the efficiency of the modified model in describing the deformation behavior of the steel. The true stress-true strain curves exhibit a peak stress at a very small strain, after which the flow stresses decrease until high strains, showing a typical dynamic recrystallization (DRX) behavior of the steel under the deformation conditions of lower strain rates.