汽车用钢板弹簧失效分析

目的 研究汽车用钢板弹簧断裂失效原因.方法 通过宏观分析、金相检验、力学性能分析、材质分析、断口电镜扫描及能谱分析等测试手段,对汽车用钢板弹簧的断裂失效原因进行分析.结果 汽车用钢板弹簧的失效模式为疲劳裂纹源于表面腐蚀坑处的高周腐蚀疲劳断裂.首先,板簧表面存在异常磨损,导致防护漆层局部脱落,裸露的金属基体在腐蚀环境下出现表面腐蚀坑,外界拉应力作用及腐蚀坑底部应力集中叠加导致早期疲劳裂纹在腐蚀坑底部萌生并扩展.其次,板簧表面存在脱碳现象,导致板簧表面硬度及强度降低,表面耐腐蚀性能下降,为早期疲劳裂纹的萌生创造了条件.结论 控制热处理质量,避免表面脱碳;做好定期维护保养,在簧片间加石墨润滑剂,防止长时间干磨或挤压碰撞导致漆层早期脱落;及时清理附着的泥水,减小腐蚀几率;对存在隐患的在用板簧及时更换.

Failure Analysis on Fracture of Automobile Leaf Spring

This paper aims to investigate the fracture failure reasons of leaf spring for automobile. The fracture causes of automobile leaf spring were analysed by means of macroscopic analysis, metallographic examination, mechanical performance analysis, materials analysis, scanning electron microscopy and energy spectrum analysis.The results showed that the failure mode of the leaf springs for automobiles is fatigue cracking originating from high circumferential corrosion fatigue fracture at surface corrosion pits. First of all, the abnormal wear on the surface of the leaf spring lead to the partial peeling of the protective paint layer, the exposed metal substrate produced surface corrosion pits in the corrosive environment, the stress superposition of the external tensile stress and the stress at the bottom of the corrosion pit resulted in early fatigue cracks initiated at the bottom of the corrosion pits. Secondly, there is decarburization on the surface of the plate spring, which leads to the reduction of the surface hardness and strength of the plate spring and the reduction of the surface corrosion resistance, creating the conditions for the sprouting of early fatigue cracks. The conclusions are as follows:The quality of heat treatment can be controlled to avoid surface decarburization; regular maintenance should be carried out, and graphite lubricant should be added between the reeds to prevent the paint layer from falling off early due to long-term dry grinding or extrusion collision; The attached mud and water should be cleaned in time to reduce the corrosion probability; The leaf spring in use with hidden dangers should be replaced in time.