淬火温度对渗碳齿轮钢C64显微组织及力学性能的影响

通过硬度、拉伸、冲击测试,以及光学显微镜(OM)、扫描电镜(SEM)等分析手段研究了C64钢在不同温度淬火过程中的显微组织和力学性能的变化。结果表明:当淬火温度低于950 ℃时,C64试验钢的显微组织中板条马氏体较为细小;当温度高于950 ℃时,板条马氏体急剧长大。随着淬火温度的升高,碳化物开始逐渐溶解,950 ℃时几乎全部溶解。钢的强度、硬度随着淬火温度的升高呈现下降的趋势;钢的伸长率、断面收缩率、冲击吸收能量随着淬火温度的升高表现出先升高后下降的趋势,并在950 ℃时达到最大值。试验钢最佳淬火温度为950 ℃,能够获得组织均匀、细小的板条状马氏体组织。此时,试验钢的抗拉强度为1122 MPa,屈服强度为1106 MPa,伸长率为11.40%,断面收缩率为25.20%,冲击吸收能量为191.0 J,能达到强韧化的最佳匹配。

Effect of quenching temperature on microstructure and mechanical properties of gear steel C64

Changes of microstructure and mechanical properties of C64 steel during quenching at different temperatures were studied by means of hardness, tensile and impact tests, and with optical microscope (OM) and scanning electron microscope (SEM). The results show that when the quenching temperature is lower than 950 ℃, the lath martensite in the microstructure of the tested steel C64 is relatively fine, but when higher than 950 ℃, the lath martensite grows dramatically. With quenching temperature increasing, the carbides dissolve gradually until dissolve almost completely at 950 ℃; the strength and hardness of the steel tend to decrease, while the elongation, percentage reduction of area and impact absorbed energy of the steel tend to increase first and then decrease and reach their maximum values at 950 ℃. The optimum quenching temperature of the tested steel is 950 ℃, at which uniform and fine lath martensite can be obtained; the tensile strength, yield strength, elongation, percentage reduction of area, and impact absorbed energy of the tested steel is respectively 1122 MPa, 1106 MPa, 11.40%, 25.20%, 191.0 J, which can offer the best match of strengthening and toughening.