Study on the constitutive equation of hot forming of boron steel sheet

The high temperature constitutive equation of boron steel sheet can describe the relationship of the thermodynamic parameters on the hot forming process of boron steel sheet. It can reflect the relationship between flow stress and strain, the temperature and strain rate, and is indispensable in the forming simulation of hot stamping forming process. In this paper, around the ultra-high-strength boron steel sheet 22MnB5, conduct thermodynamic tensile test on it. And the high-temperature constitutive equation of the high-strength steel sheet under the high-temperature austenite state is established according to the deformation theory. Finally, it is confirmed that the improved Norton-Hoff constitutive equation fitted with the experimental results is in good agreement with the flow stress relationship of boron steel 22MnB5.