1800MPa级超高强热成形钢组织性能演变及奥氏体化工艺制度研究

Study on microstructure evolution and austenitizing process of 1800 MPa grade ultra-high strength hot stamping steels

对不同奥氏体化温度及保温时间条件下的1800 MPa级超高强热成形钢组织性能演变进行了试验研究,确定了最佳的热成形奥氏体化工艺制度。结果表明,当奥氏体化温度及保温时间分别达到840℃、3 min时,1800 MPa级超高强热成形钢淬火后的组织均为马氏体,且马氏体组织随着奥氏体化温度的升高及保温时间的增加逐渐粗大,抗拉强度逐渐下降。当奥氏体化温度为840℃时,抗拉强度、伸长率及强塑积分别可以达到1861.3 MPa、6.88%、12.81 GPa·%;当保温时间为3 min时,抗拉强度、伸长率及强塑积分别可以达到1851.28 MPa、6.84%、12.66 GPa·%。最佳奥氏体化工艺制度为:奥氏体化温度840℃,保温时间3 min。

The evolution of microstructures and properties of 1800 MPa ultra-high strength hot stamping steels under different austenitizing temperatures and holding times were experimentally studied in this paper,and the optimum hot stamping austenitizing process was established.The results show that when the austenitizing temperature and holding time reach 840℃and 3 min,respectively,the quenched microstructures of the hot stamping steel is consisted of martensite,and the martensite becomes coarser with the increase in temperature and holding time.The tensile strength decreases gradually with the increase of the austenitizing temperature and holding time.When the austenitizing temperature is 840℃,the tensile strength,elongation and strength-ductility product can reach 1861.3 MPa,6.88%and12.81 GPa·%,respectively.When the holding time is 3 min,the tensile strength,elongation and strengthductility product can reach 1851.28 MPa,6.84%and 12.66 GPa·%,respectively.The austenitizing temperature of 840℃and holding time of 3 min are selected as the optimum austenitizing parameters.