Abstract: The leaf spring of a light passenger car frequently breaks problems during the durability test of the vehicle. Through macro and micro analysis of the fracture surface, chemical composition analysis, hardness test, metallographic structure detection and analysis, as well as analysis of the position of the milling step and the stress characteristics of the leaf spring, this paper determines the root cause of the fracture of the leaf spring and formulates improvement measures, and is verified through the bench test and vehicle durability test. The results show that the milling range on both sides of the leaf spring lug is too long, resulting in milling steps at the R corner of the leaf spring, which further increases the stress concentration here and causes the leaf spring to break. The issue is solved by reducing the milling length on both sides of the leaf spring lugs.

Key words: Light passenger car; Leaf spring; Fracture failure

摘要： 某轻型客车钢板弹簧在整车耐久试验过程中频繁出现断裂问题。文章通过断口宏观和 微观分析、化学成分分析、硬度测试、金相组织检测分析，以及铣削台阶位置和板簧受力特 征分析，确定了钢板弹簧断裂的根本原因并制定了改进措施，结合台架试验及整车道路试验 进行了验证。结果显示，钢板弹簧卷耳两侧铣削范围过长，导致板簧簧片 R 角处存铣削台阶， 使得此处应力集中进一步提高，导致钢板弹簧在此处断裂。减小钢板弹簧卷耳两侧铣削长度， 问题得以解决。

关键词: 轻型客车；钢板弹簧；断裂失效