河北冶金

出于节能减排、增加燃油经济性和满足日益严厉的安全法规的需要，超高强度钢热冲压成形零部件在汽车上身的应用比例逐年增加。详细介绍了22MnB5钢热冲压工艺参数的设计规范，及裂纹失效问题的控制。为保证淬火后零件微观组织中马氏体含量≥95%,抗拉强度≥1 500 MPa的要求，奥氏体化加热温度应控制在900～950℃、淬火冷却速度≥30℃/s;模具设计时需进行导热量计算及导热系统结构设计，保证热冲压零件的成形减薄率<15%、弯曲角圆弧半径R≥13 mm;为抑制应力集中导致的开裂，系统导热量在整个零件表面分布应均衡一致，导热水管外壁距模具型腔表面的垂直散热距离应均匀一致为10 mm,零部件热处理后显微组织中应减少马氏体粗大化，避免混晶。

Due to the need for energy saving and emission reduction, increasing fuel economy and meeting increasingly stringent safety regulations, the proportion of ultra-high strength steel hot stamped parts in the upper body of automobiles is increasing year by year. The design specifications of the hot stamping process parameters of 22MnB5 steel and the control of crack failure problems are introduced in detail. In order to ensure that the martensite content in the microstructure of the parts after quenching is ≥95%, and the tensile strength is ≥ the requirements of 1 500 MPa, the austenitizing heating temperature should be controlled at 900～950 ℃, and the quenching cooling rate should be ≥30 ℃/s; during mold design, heat conductivity calculation and thermal conduction system structure design are required to ensure that the forming thinning rate of hot stamped parts is <15%, and the radius of the arc of the bending angle is R≥13 mm; in order to inhibit the cracking caused by stress concentration, the heat conduction distribution of the system should be balanced and consistent on the surface of the entire part, the vertical heat dissipation distance between the outer wall of the hot water pipe and the mold profile should be uniform and consistent to be 10 mm, and the coarsening of martensite should be reduced in the microstructure of the parts after heat treatment to avoid crystal mixing.