根据φ700 mm轧机用H11轧辊的工况, 采用化学成分分析、力学性能检测、显微组织和断口观察等方法对其断裂失效原因进行了分析。结果表明: 轧辊断裂性质是弯曲-扭转疲劳断裂; 其断口上有多个疲劳源, 疲劳源位于轧辊的表面或次表面; 由于轧辊材料部分元素含量超标, 轧辊表面硬度比标准规定的低, 而且材料中存在较多弥散分布的Al2O3、MnS等氧化物和硫化物夹杂, 这些都是产生疲劳裂纹的内因; 在扭转和弯曲应力共同作用下, 疲劳裂纹从轧辊轴径过渡圆角处等应力集中区域开始萌生, 并沿与轴径呈约45°的方向扩展, 最终导致轧辊断裂失效。

The reasons for fracture failure of a rolling mill roller made of H11 steel were analyzed through chemical composition analysis, mechanical property test, microstructure and fracture observation according to its working conditions. Results show that the failure mode of the roller was fatigue fracture resulting from co-effect of bending and twisting. There were several fatigue sources on the fracture close to the surface and the subsurface of the roller. The surface hardness of the roller was lower than standard value because of some elements′ contents beyond standard range. There were many inclusions of oxides and sulfides like Al2O3 and MnS, distributing in the roller material dispersively. These were internal cause of generation of fatigue crack. Under the co-effect of bending and twisting, fatigue cracks initiated from the stress concentration zones of the roller, such as the transition round angle zone under the neck, then propagated along the direction of 45° angle with the roller axis, resulting in the roller fracture failure at last.