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在双面对滚式接触疲动试验机上进行了高应力接触疲劳试验。赫芝应力为560～660公斤/毫米~2,采用渗碳、碳氮二元共渗和碳氮硼三元共渗处理试样。试验结果表明:表面化学热处理强化零件承受高应力接触交变载荷作用时,其失效方式是疲劳剥落.剥落方式是浅层剥落、压溃和表面微统三类。高应力浅层渗层同时出现浅层裂纹和深层裂纹。探讨了两种裂纹形成原因,针对两个危险区,计算了裂纹产生的两个临界比值τ_(max)~(45)max/HV和τ~(45)/HV。根据疲劳微裂纹的形态和位置,提出了平行最大切应力和45°方向最大切应力都能引起疲劳。同时论证了浅层裂纹在一定深度范围内分布是由于最大切应力存在一个峰值区的缘故。不同的工艺类别是通过沙层显微组织和精细结构影响疲劳抗力,三元共渗优于二元共渗,二元共渗优于渗碳。
High-stress contact fatigue test was carried out on the double-faced roller contact fatigue tester. Hertzian stress of 560 to 660 kg / mm ~ 2, the use of carburizing, carbonitriding and carbonitriding boron dual ternary treatment sample. The test results show that the failure mode of the parts strengthened by surface chemical heat treatment is high stress contact alternating load, and the failure mode is fatigue peeling, and the peeling mode is shallow peeling, crushing and surface micro-system. High-stress shallow seepage layer with shallow cracks and deep cracks. The reasons for the formation of two kinds of cracks were discussed. Two critical ratios τ_ (max) ~ (45) max / HV and τ ~ (45) / HV of the crack were calculated for the two hazardous areas. According to the morphology and location of fatigue microcracks, it is proposed that the maximum parallel shear stress and the maximum shear stress in the direction of 45 ° can cause fatigue. At the same time, it is demonstrated that the distribution of shallow cracks in a certain depth is due to the existence of a peak area in the maximum shear stress. Different process categories affect the fatigue resistance through the microstructure and fine structure of sand layer, ternary co-permeation is better than binary co-permeation, binary co-permeation is better than carburizing.