Constitutive model of high-temperature rheological behavior for S55C steel
The isothermal rheological compression experiments of S55C steel material were conducted by thermo-mechanical simulator ma-chine Gleeble-3180 at deformation temperature of 850-1000℃and strain rate of 0.01-10 s-1,and the high-temperature hot deformation be-havior of the material was studied.Then,based on the true stress-true strain curve obtained from the experiment,the influence laws of true strain,deformation temperature and strain rate on rheological stress were analyzed,and an Arrhenius constitutive model with strain compen-sation of S55C steel was established to analyze the fitting accuracy of the model further.The results show that the plastic deformation part in the hot compression deformation process of S55C steel can be divided into three stages.In the early deformation stage,the rheological stress increases sharply with the increasing of strain,the growth rate of rheological stress slows down in the middle stage of deformation,the materi-al undergoes a struggle between work hardening and dynamic softening,resulting in peak stress after reaching equilibrium,and the rheologi-cal stress in the later stage of deformation shows different change trends under different strain rates.At low strain rate,the rheological stress shows the characteristics of decreasing,and the softening form in hot compression deformation is dominated by dynamic recrystallization,while at high strain rates,the rheological stress tends to stabilize within the peak stress range,and the softening form is mainly dynamic re-covery.By comparing and analyzing the predicted results of the material constitutive model with the actual experimental data,the correlation coefficient of the Arrhenius constitutive model with strain compensation is 0.94844,and the average absolute relative error is 8.76285%,in-dicating that the constitutive model can well describe the high-temperature hot deformation behavior of S55C steel.
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