Modelling of hot compressive deformation behaviour of 55 steel considering strain

The hot compressive deformation behaviour of 55 steel was investigated using isothermal compression tests in the temperature range of 1,123-1,273 K and a strain rate range of 0.1-10 s(-1). Increased deformation temperature and decreased strain rate resulted in a lower flow stress at a given strain. With an increase in strain, most of the flow stresses increased rapidly at first, followed by a fall towards a steady state after a peak stress was reached, which was more significant at higher temperatures and a smaller strain rate. A constitutive model was established based on the Arrhenius equation. Furthermore, the influence of strain was included in the constitutive equation by considering its effect on different material constants. The accuracy of the developed constitutive equations was evaluated using standard statistical parameters. The predicted stress-strain values of 55 steel correlated well with the experimental results.