Fe-1.3C-1.5Cr-1.5Al超高碳钢等温淬火组织与性能研究

Research on Isothermal Quenched Structures and Properties of Ultra-high Carbon Steel Fe-1.3C-1.5Cr-1.5Al

为获得综合性能良好、在工模具上具有广泛应用前景的超高碳钢,利用SEM、维氏硬度计、拉伸试验机和冲击实验机,在确定Al温度的基础上,对Fe-1.3C-1.5Cr-1.5Al超高碳钢在300℃进行等温淬火,研究了等温时间对组织和性能的影响规律。结果表明,Fe-1.3C-1.5Cr-1.5Al超高碳钢Al温度在810℃左右;在300℃下等温淬火能够获得下贝氏体、残余奥氏体及未溶碳化物复相组织,且随等温淬火时间的延长,下贝氏体体积分数增加、残余奥氏体减少,超高碳钢的硬度增大、韧性降低。Fe-1.3C-1.5Cr-1.5Al超高碳钢在830～850℃×1 h奥氏体化后,经300℃等温淬火2 h,其抗拉强度为1 750 MPa,总伸长率为6.9%,硬度为560 HV,冲击吸附功为4J,能够达到工模具钢室温性能要求。

In order to obtain the ultra-high carbon steel Fe-1.3C-1.5Cr-1.5Al with good mechanical properties,based on the confirming of the A1 temperature point of this steel,the influences of the isothermal time at 300 ℃ on the microstructure and properties have been researched.The microstructures were observed by the scanning electron microscope（SEM）,the mechanical properties were tested by vickers hardness tester,tensile machine and impact-toughness tester.The results showed that the Al temperature point of this steel was about 810 ℃.The microstructure observation indicated that the microstructure austempered at 300 ℃ was ultra-fine low bainite ferrite,retained austenite,and unsolvable cementite.And with the prolongation of austemper time,the volume fraction of retained austenite decreased,the microstructure got finer,the hardness increased and the plasticity decreased.With the prolongation of austemper time,the hardness increased and the plasticity decreased.The ultra-high carbon steel Fe-1.3C-1.5Cr-1.5Al after austenitizing at 830～850 ℃ for 1 hour and austempering at 300 ℃ for 2 hours,the mechanical properties could fit the performance requirements of die steel at room temperature,namely the tensile strength was 1 750 MPa and total specific elongation was 6.9% and hardness was HV560 as well as the shock absorption was 4 J.