小模数地铁联轴器的离子渗氮工艺

Ion nitriding process for small modulus subway couplings

针对材料为31CrMoV9合金结构钢、模数为4 mm的地铁联轴器开展离子渗氮工艺研究,采用光学显微镜、显微硬度计和弯曲疲劳试验机对其进行渗氮层表面硬度、渗氮层深度、显微组织分析及弯曲疲劳性能测试。结果表明,保持NH_3流量不变时,随着Ar流量的增加,从齿顶到齿根部渗氮层深度均匀性及齿轮的弯曲疲劳强度增加,表面化合物层厚度更加均匀。最终确定渗氮工艺为540℃×36 h, NH_(3)∶Ar=10∶7,炉压为280 Pa时的离子渗氮工艺满足图纸技术要求,最终经实际生产验证,具有较好的实际操作性。

Research on ion nitriding process was conducted with respect to subway coupling made of 31CrMov9 structural alloy steel and with modulus of 4 mm.The surface hardness and the depth of the nitrided layer and microstructure were analyzed and the bending fatigue property test was conducted by means of optical microscope,microhardness tester and fatigue bending machine.The results show that when NH,flow unchanged,the uniformity of the nitrided layer depth from tooth crest to tooth root and the bending fatigue strength increase,and the thickness of the surface compound layer is more uniform with the increase of Ar flow.The nitriding process which meets the drawing's technical requirements is ultimately determined as follows:nitriding at 540℃for 36 h and flow ratio of NH_(3) to Ar is 10 to 7 to get 280 Pa furnace pressure.Finally,through the actual production verification,the nitriding process has good operability.