钢丝绳捻制断裂失效分析

Failure analysis of wire rope twisting fracture

根据制绳钢丝在捻制过程中的受力状态,采用扫描电镜和金相检测技术,对断口形貌的微观特征和裂纹分布形式进行分析,总结钢丝绳捻制断裂失效原因。斜楔状断口的断裂面与钢丝轴线的夹角很小,部分断口根部存在与轴线成45°的横向裂纹;阶梯状断口的断裂面为多个与钢丝轴向平行的阶梯状小平面;而混合状断口的断裂面中不同区域分别具有斜楔状和阶梯状断口的形貌特征。对断裂样品的纵向组织进行金相检测,分析不同形式断口裂纹的形态和走向。结果表明,制绳钢丝在捻制过程中发生断裂的原因是在扭转载荷、弯曲载荷或其组合形式作用下,钢丝表面产生横向裂纹,并随着裂纹扩展导致断裂。

To analyze the microstructure of fracture pattern and crack distribution form by adopting SEM and metallographic examination technology according to the stress condition of steel wire for rope during twisting process, the wire rope twisting fracture failure reason is summarized. The included angle between fracture surface of wedge fracture and steel wire axis is small, part fracture root exists 45° transverse crack with axis. The fracture surface of terraced fracture is several small ter- raced planes which are parallel to wire axis. Different areas of mixed shaped fracture surface have wedge shape and terraced shape fracture morphology respectively. The longitudinal structure of cracked sample is metallographic examined, the crack form and direction in different fracture is analyzed. Results shows that the reason of steel wire rope twisting fracture is transverse crack initialized under the torsion load, bending load, or its combination, steel wire surface occurs transverse cracks, eventually fracture along with crack extended.