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冷轧工作辊的抗接触疲劳性能是其抵抗早期失效的主要性能之一。它与轧辊表层组织结构和残余应力状态有关。组织结构和残余应力取决于轧辊的热处理工艺。笔者已就淬火温度对86CrMoV7钢抗接触疲劳性能的影响进行了研究。为进一步了解残余奥氏体和残余应力的作用,本工作就冷处理对86CrMoV7钢的抗接触疲劳性能的影响进行了研究。将试样在930℃油中淬火,并于0、-35、-74和-105℃冷处理,150℃回火。测量各组试样的接触疲劳寿命、残余奥氏体量、残余应力和硬度。并对显微组织和剥落断口进行了研究。结果表明,淬火后不经冷处理和-35℃冷处理的试样具有高的接触疲劳寿命,其余各组寿命均较低。随冷处理温度下降,残余奥氏体量减少,硬度增高,残余应力变化不大。这些变化是由于冷处理时奥氏体向马氏体转变的缘故。接触疲劳试验后,试样中残余奥氏体量进一步减少,硬度和残余应力都有增加。这反映了接触疲劳过程中形变和相变的综合效果。研究认为,86CrMoV7钢淬火组织中,残余奥氏体的稳定性是影响其抗接触疲劳性能的重要因素之一。一定量的稳定的残余奥氏体与高的表面硬度和较高的残余压应力相结合将有利于提高钢的接触疲劳性能。主要结论是冷处理可以消除淬火钢中不稳定的残余奥氏体,并可以提高钢的硬度和残余压应力。因而,对提高86CrMoV7钢的抗接触疲劳性能是有利的。
The anti-contact fatigue performance of cold-rolled work rolls is one of its key properties against early failure. It is related to the surface structure of the roll and the residual stress state. Tissue structure and residual stress depend on the roll heat treatment process. The author has studied the influence of quenching temperature on the contact fatigue resistance of 86CrMoV7 steel. In order to further understand the effect of retained austenite and residual stress, the work on the impact of cold treatment on the contact fatigue resistance of 86CrMoV7 steel was studied. The specimens were quenched in oil at 930 ° C and were cold treated at 0, -35, -74 and -105 ° C and tempered at 150 ° C. The contact fatigue life, residual austenite, residual stress and hardness of the specimens were measured. The microstructure and flaking fracture were studied. The results show that the samples after quenching without cold treatment and cold treatment at -35 ℃ have high contact fatigue life, and the remaining groups have lower life expectancy. As the cold treatment temperature decreases, the amount of retained austenite decreases, the hardness increases, and the residual stress does not change much. These changes are due to cold austenitic to martensitic transformation. After the contact fatigue test, the amount of retained austenite in the sample further decreases, and both the hardness and the residual stress increase. This reflects the combined effect of deformation and phase change during contact fatigue. It is considered that the stability of residual austenite in the quenched microstructure of 86CrMoV7 steel is one of the important factors affecting the contact fatigue resistance. A certain amount of stable residual austenite combined with high surface hardness and high residual compressive stress will help improve the contact fatigue properties of steel. The main conclusion is that cold treatment can eliminate the unstable residual austenite in hardened steel and increase the hardness and residual compressive stress of steel. Therefore, it is beneficial to improve the contact fatigue resistance of 86CrMoV7 steel.