Effect of aging treatment on microstructure and mechanical properties of ultra-high strength 20Mn2Cr automotive steel
The effects of aging temperature,double-step aging treatment and the precipitation behavior of carbides on the microstructure and mechanical properties of ultra-high-strength automotive steel 20Mn2Cr were investigated.The results indicate that the hardness of 20Mn2Cr steel after dual-stage aging treatment is significantly higher than that after single-stage aging.For the double-step aged steel,when the first-step aging temperature is set at 550 ℃,the optimum comprehensive mechanical properties with tensile strength of 1 418.1 MPa,elongation of 10.8％,and product of strength and elongation of 15.3 GPa·％can be obtained.SEM observations show that the double-step aging treatment contributes to the design and control of the multi-phase microstructures of 20Mn2Cr steel.The matrix of the steel after 550 and 300 ℃ double-step aging treatment consists of granular bainite and martensite.A large number of fine Cr-rich carbides can also be found in the double-step aging treated steel.The design of multi-phase microstructures is the primary reason for the enhancement of strength and the achievement of excellent match between strength and plasticity of 20Mn2Cr steel.
NETL
NSTL
万方数据
