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为了优化中碳贝氏体钢支承辊的磨削换辊工艺,研究了其接触疲劳时的裂纹萌生和扩展。在JPM-1B型接触疲劳试验机上测定了水润滑条件下的接触疲劳失效寿命曲线,并以裂纹沿平行表面方向扩展为判断标准,通过解剖试样的方法测定了裂纹萌生寿命曲线。结果显示两条曲线均在最大接触应力为0.86GPa处发生弯折,裂纹萌生寿命约为失效寿命的70%～80%。在扫描电镜下对试样观察发现:当接触应力较低时垂直裂纹占主导地位,而接触应力较高时棘齿裂纹占主导地位。这两种裂纹都具有一般短裂纹的特点。
In order to optimize the grinding and roll-changing process of the middle-carbon bainitic steel back-up roll, the crack initiation and propagation during contact fatigue were studied. The contact fatigue failure life curve under water lubrication condition was measured on JPM-1B contact fatigue tester, and the crack initiation life curve was measured by dissecting the sample with the crack extending along the parallel surface as a criterion. The results show that both curves bend at the maximum contact stress of 0.86GPa, and the crack initiation life is about 70% ~ 80% of the failure life. The observation of the sample under a scanning electron microscope revealed that the vertical cracks dominate when the contact stress is low and the ratcheting cracks dominate when the contact stress is high. Both types of cracks have the general characteristics of short cracks.