• boron alloy steel;
  • hot stamping;
  • mechanical properties;
  • microstructure;
  • spring-back

In this paper, the hot stamping mold with a cooling system was designed. The forming process was investigated. The effect of contact state between the blank and the mold on the mechanical properties of the ultra high strength steel was also analyzed. The results show that the spring-back angles are greatly reduced after hot stamping, compared with stamping at room temperature. The tensile strength and yield strength of the Boron alloy steel sheet are improved. In addition, it is found that the mechanical properties and microstructures of the hot stamped part show an inhomogeneous phenomenon due to the influence of the cooling condition at the blank/mold interface. The sidewall of the part has a higher tensile strength and a lower elongation compared with the other locations.