自行车多飞飞轮轮芯冷挤压凸模具断裂失效原因探析

Failure Analysis of the Cold--extrusion Die for

本文以某自行车集团多飞飞轮轮芯冷挤压模具的凸模为研究对象，通过模具结构的分析、挤压力计算、光学显微镜与扫描电子显微镜的组织结构观察、失效模具断口形貌分析及微区成分测试等探讨了自行车多飞飞轮轮芯冷挤压模具断裂失效的原因。实验发现，失效模具的显微组织中明显存在不均匀带状分布的碳化物，而断裂裂纹发生部位为碳化物集中区。模具组织中存在不均匀带状分布的碳化物是产生断裂失效的主要原因。

The fracture failure reasons of the cold--extrusion die for the core of bicycle flywheel was studies by means of conformation characterization, extrusion pressure calculation, microstructure observation by optical and scanning electron microscope, morphology analysis of fracture surface, and micro--area chemical component measurement. The results show that there is a large amount of non--uniform carbide which appears in zonal distribution in the microstructure of the failure die, and that the fracture cracks are generated in the region where the carbide exists in a group. The existence of the non--uniform carbide can be regarded as the primary cause of fracture failure.