自行车多飞飞轮轮芯冷挤压模具失效分析

Failure Analysis of Cold Extruding Die for Molding of Bicycle Multi-flywheel

采用光学及扫描电镜观察分析了自行车多飞飞轮轮芯冷挤压凸模显微组织结构,探究了其断裂失效的原因。观察显微组织发现,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。断口形貌及裂纹附近EDS测试分析表明,碳化物集中区为断裂裂纹发生区。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内在原因,而模具在冷挤压成型过程中形成的应力积累是导致模具断裂失效的外在诱因。

The microstructure of the cold extruding die for molding of bicycle multi-flywheel was observed by optical and scanning electron microscopy. The cause of fracture failure was researched. The results show that many uneven carbide belts obviously distribute in the microstructure. The results of fracture appearance and the EDS testing nearby fracture surface indicate that the carbide concentration region is the reason of generating fracture crack. The existence of uneven carbide belts is the inner reason of fracture failure and the stress accumulation during the process of cold extruding is its extemal incentives.