New constitutive model and hot processing map for A100 steel based on high-temperature flow behavior

To predict the flow behavior and identify the optimal hot processing window for A100 steel, a constitutive model and a hot processing map were established using true stress-strain data extracted from isothermal compression tests performed at temperatures ranging from 1073 to 1353 K and strain rates varying between 0.01 and 10 s^-1. The results indicate a strong linear trend between the logarithmic stress and the reciprocal of temperature, along with a significant quadratic relationship between the logarithmic stress and logarithmic strain rate. With a correlation coefficient of 0.9913, the new constitutive model demonstrates an excellent predictive capability for the flow behavior of A100 steel. A significant dynamic recrystallization occurs when the energy dissipation rate exceeds 25 %, resulting in a uniform equiaxed grain structure after deformation. The unstable regions primarily occur in high strain rate and low-temperature zones, where the microstructures are typically coarse and elongated. This structural characteristic adversely affects the mechanical properties. Avoiding these conditions during hot forming of A100 steel is crucial. The optimal hot forming windows for A100 steel are achieved within a temperature range of 1153-1353K and a strain rate range of 0.01-10 s^-1, where complete dynamic recrystallization occurs.