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采用光学显微镜跟踪测量法研究了支承辊钢滚动接触疲劳垂直短裂纹的形成和不扩展特性。结果表明:这种短裂纹生成很快、初始扩展速率非常高,但很快就停止扩展;经过大约表面损伤寿命的70%~80%周次循环后,一部分短裂纹又转向沿圆周方向且平行于表面扩展,并具有长裂纹扩展特征。利用垂直短裂纹的这种不扩展特性及其可跟踪性,将其转向扩展作为区分长短裂纹分界点判据。根据这种判据,实验测得残余拉压应力下的寿命比为0.5~0.54,与理论计算的残余拉压应力下的寿命比0.333~0.375相差较大。
The formation and non-expanding characteristics of the vertical short-crack of the rolling contact fatigue of the backup roll were investigated by optical microscopy. The results show that this kind of short crack grows quickly and its initial expansion rate is very high, but it stops expanding rapidly. After about 70% ~ 80% of the life of the surface damage cycle, some short cracks turn to the circumferential direction and parallel Expanded on the surface with long crack propagation characteristics. By using this non-expanding characteristic of vertical short crack and its traceability, it is turned to be extended as a criterion for distinguishing the length crack from the crack crack. According to this criterion, the experimentally measured life-span ratio under the residual tensile-compression stress is 0.5-0.54, which is quite different from the theoretical life-span ratio under the residual tensile-compression stress of 0.333-0.375.