磁处理对GCr15轴承环冷轧-淬火残余应力影响规律

Influence Rule of Steel GCr15 in Process of Cold Ring Rolling-quenching by Magnetic Treatment

冷轧环工艺材料利用率高、精度高、表面质量好、疲劳寿命长,是轴承环的先进塑性加工工艺。冷轧与淬火是轴承环冷轧加工的两个关键环节,其引起的残余应力会对轴承环几何精度和组织性能产生重要危害,需要进行有效处理。分别对冷轧和淬火阶段GCr15轴承环进行磁处理,利用X射线衍射法测试比较冷轧轴承环在磁处理、常规去应力退火以及去应力退火与磁处理结合三种处理方式下的残余应力,以及淬火后轴承环在磁处理、常规回火和回火与磁处理结合三种处理方式下的残余应力。结果表明,磁处理对轴承环冷轧和淬火残余应力有一定的影响;对于冷轧后轴承环,磁处理对残余应力作用效果不如去应力退火好,而磁处理与去应力退火结合对残余应力作用效果比去应力退火好;对于淬火后轴承环,磁处理对残余应力作用效果不如回火好,而磁处理与回火结合对残余应力作用效果比回火好。由此得知,利用磁处理结合冷轧和淬火轴承环常规处理方法能有效改善环件残余应力。引入弗兰克-瑞德源的位错增殖机制,从位错角度阐释磁处理对残余应力的作用机理。揭示磁处理对轴承环冷轧-淬火残余应力的影响规律和作用机理,为轴承环冷轧残余应力控制提供理论和技术依据。

Cold ring rolling technology has the benefits of high utilization, high precision, excellent surface quality, long fatigue life, which is the advanced plastic processing technology of bearing ring. Cold rolling and quenching of bearing ring are two key links of cold rolling. The residual stress of bearing ring due to cold ring rolling and phase transformation by quenching will seriously affect geometric precision and microstructures and properties, so it is needed for effective treatment. In this thesis, steel GCr15 rings in cold rolled and quenched treated by magnetic is studied. The residual stress of cold-rolled bearing rings in magnetic treatment, conventional stress relief annealing, stress relief annealing combined with magnetic treatment and the residual stress of bearing rings in magnetic treatment, tempering, tempering combined with magnetic treatment after quenching have been tested. Experimental results reveal that magnetic treatment has the effects on the residual stress of bearing rings in cold rolled and quenched. The residual stress to the rings treated by stress relief annealing combined with magnetic treatment after cold rolling reduce the most, followed by conventional stress relief annealing, the worst effect is magnetic treatment. The most obvious effect of residual stress to the bearing rings is the way treated by tempering combined with magnetic treatment after quenching, followed by tempering, the worst effects is magnetic treatment. As a result, the way to magnetic treatment combined with conventional treatment methods after cold rolling and quenching of bearing rings can reduce the residual stress effectually. To reveal the mechanism action of the residual stress by magnetic treatment from the perspective of dislocation, the mechanism of Frank-Read source dislocation multiplication is introduced. The influence rule and the effect mechanism of residual stress for steel GCr15 during cold ring rolling-quenching on the performance of bearing ring have been revealed, which provides theories and technical basis for the control of residual stress for cold-rolled bearing rings.