冷却速率对新型C61齿轮钢力学性能和微观组织的影响

借助光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)等设备，通过力学性能测试和显微组织观察，探究炉冷、水冷、石棉缓冷三种不同冷却方式对C61钢热轧态组织和性能的影响，对比不同状态下试验钢的性能。试验结果表明：冷却速度对试验钢的性能影响较大，由于冷却速率V_水冷>V_石棉缓冷>V_炉冷,导致试验钢在水冷条件下强度、硬度均高于炉冷和石棉缓冷处理时的性能；热轧后经水冷，试验钢的抗拉强度(R_m)和断面收缩率(Z%)分别为1450 MPa和62.7%,XRD分析得知，热轧后随冷却速率增加钢的残余奥氏体含量增多，面心立方的奥氏体有利于提升试验钢的韧性。可见，热轧水冷后的试验钢经过950℃加热1 h,水淬，经过-73℃冷处理1 h后，恢复到室温，最后在482℃回火16 h,空冷至室温是最佳工艺方案。

Effect of Cooling Rate on Mechanical Properties and Microstructure of New C61 Gear Steel

With the help of optical microscope(OM),scanning electron microscope (SEM),transmission electron microscope(TEM),X-ray diffractometer (XRD)and other equipment,through mechanical performance testing and microstruc- ture observation,we explored the effects of furnace cooling,water cooling,and asbestos slow cooling three different cooling methods on the structure and properties of the hot-rolled condition C61 steel,compared the performance of the test steel in different conditions. The experimental results show that the cooling rate has a great influence on the performance of the test steel. Due to V_{water cooling} ＞ V_{asbestos slow cooling} ＞ V_{furnace cooling},the strength and hardness of the test steel under water cooling condition are higher than those of furnace cooling and asbestos slow cooling. After hot rolling and water cooling,the tensile strength(Rm)and reduction of area(Z%)of the test steel are 1450 MPa and 62.7%,XRD analysis shows that the residual austenite content of the steel increases with the increased cooling rate after hot rolling,and the surface-centered cubic austenite is conducive to improve the toughness of the test steel. It can be seen that the test steel after hot rolled + water cooling was heated at 950 ℃ for 1 h quenched by water,and cold treatment at -73 ℃ for 1 h, then returned to room temperature,finally tempering at 482 ℃ for 16 h,air cooling to room temperature is the best process scheme.