梯度化加热调控微观组织实现变强度热冲压工艺

Variable strength hot stamping process realized by gradient heating to regulate microstructure

开发了一种变强度热冲压工艺,可以对零件进行微观组织和力学性能调控。利用感应线圈对坯料进行梯度化加热,使局部区域奥氏体化,进而调控淬火后各区域的微观组织,从而获得变强度零件。实验以退火态及冷轧态的热冲压钢来研究该工艺,软化区组织均为珠光体+铁素体,退火态和冷轧态钢板的抗拉强度及伸长率分别为490 MPa和32%、940.4 MPa和4.2%;高强度区均为马氏体组织,退火态和冷轧态钢板的抗拉强度及伸长率分别为1532 MPa和9.1%、1485.1 MPa和8.4%;过渡区的硬度从高强区向软化区逐渐下降,性能基本平稳过渡。结果表明,对于两种不同供货态钢,该工艺均可通过微观组织调控的方法,实现零件的变强度分布。

A variable-strength hot stamping process was developed to regulate the microstructures and mechanical properties of parts,and the induction coils were used to perform gradient heating of the blank to austenitize the local area,and then regulate the microstructures of each area after quenching to obtain the variable-strength parts.Furthermore,for the hot stamping steels in annealed state and cold rolled state,experiments were applied to study the process.The microstructure of softened zone is pearlite and ferrite,and the tensile strength and elongation of the annealed and cold-rolled steel sheets are 490 MPa,32%and 940.4 MPa,4.2%,respectively.However,the microstructure of high-strength zone is all martensite,and the tensile strength and elongation of annealed and cold-rolled steel sheets are 1532 MPa,9.1%and 1485.1 MPa,8.4%,respectively.But,the hardness of transition zone gradually decreases from high-strength zone to softened zone,and the performance is basically smoothly transitioned.The results show,for two kinds of steel with different supply condition,parts with variable strength distribution can be obtained by the method of microstructure regulation.