摘要
本文研究了不同钢种、不同工艺和不同层深的组织对渗碳齿轮接触疲劳、弯曲疲劳、多冲抗力和耐磨性的影响。研究了喷丸温度的影响。对表层残余奥氏体和碳化物在提高齿轮接触疲劳强度作用方面进行了微观机制研究。进行了不同工艺处理的汽车、拖拉机齿轮的装车和台架试验。测定了接触疲劳裂纹扩展速度;残余奥氏体在接触疲劳过程中的变化,滚压前后残余应力的变化。定量计算了形变诱发马氏体吸收的能量对裂纹扩展的阻碍作用。观察了残余奥氏体含量不同的接触疲劳断口的不同微观形貌。研究表明,对于不同的工作条件不同的接触疲劳失效型式(点蚀、浅层剥落、深层剥落)的齿轮,表层中合金成分不同的残余奥氏体的作用是不同的。齿轮台架接触疲劳对比试验表明,以接触疲劳失效为主的重载齿轮,表层节圆处残余奥氏体5级左右,碳化物2级左右,齿顶角碳化物4级左右,有高的接触疲劳寿命。用渗碳—高浓度碳氮共渗(简称薄层软化工艺)可以实现表层残余奥氏体数量和碳化物的控制,并制订了相应软化金相组织级别评级图片,可作为生产上控制质量的依据。
This Paper describes some research results of the influence of microstructure,heat treatment process, depth of hardened case and strength of shot peening on the resistances of rolling contact fatigue, rotating bending fatigue, and repeated impact, as well as wear. The micromchanissm for improving rolling contact strength of gears having retained austenite and carbde in their case are related. The running test and gear rig test for automobile and tractor had been carrled out. The crack prop-agation rate of contact fatigue is determined and measured. The changes of retained austenite and residual stress are observed and measured during con-tact fatigue process. The resistance of the absorbed energy of deformation in-duced martensite and the crack propagation is calculated quantitatively. The frac-ture features of contact fatigue with different amount of retained austenite are observed. The research results indicate that the effect of retained austenite with different alloy element is different under various service conditons where the contact fatigue fracture are in different mode: pitting, spalling, crashing.Gear tests show that for heavy loading gears there are rather long contadt fat-igue lifelunder under following conditions: the amount of retained austenite is about grade 5 at the pitch circle and the carbide is about grade 2, while the carbide is about grade 4 at the abbendums. Quantitative control for retained austenite and carbide in the case can be carried out by using carburizing and high carbon content catbonitriding tachnique. A set of metallographic chart has been established as a standard for quality control in production.
