Flow Stress Behavior and Governing Equation of Plastic Flow of Low-Carbon Steel at Elevated Temperatures

The effect of hot isothermal compression on the flow stress of low-carbon steel was studied using a Gleeble 3500 stimulator at temperatures from 900 to 1200°C and deformation rates from 0.01 to 10 sec^{– 1}. The flow stress was analyzed at elevated temperatures using a hyperbolic sine function. The material constants were determined in the range of true deformation rates from 0.1 to 0.7. The dislocation structure of low-carbon steel was studied after the deformation at 1100°C and cooling at a rate of 5 K/sec. A governing equation for describing and simulating the low-carbon steel behavior under high-temperature deformation was derived and justified. It was shown that the obtained equation can be used to provide a reliable and valid description of the low-carbon steel behavior under hot forming with a mean relative error of 5.1219% and a correlation coefficient of 0.9886. The equation can be used to model and optimize the process parameters of hot deformation of steel and to predict the evolution of its microstructure.