Abstract: The automotive stabilizer is an important component that ensures the smoothness, handling stability, comfort, safety, and accurate driving of the vehicle. Once the ball pin of the stabilizer bar fails, it will lead to the loss of the overall function of the car stabilizer bar, seriously threatening the safety of car driving. An analysis is conducted on the fracture cause of the ball pin in the 40Cr automotive stabilizer bar. To determine the cause of failure, a comprehensive failure analysis is conducted, including macroscopic inspection, chemical composition analysis, metallographic structure analysis, micro Vickers hardness testing, fracture analysis, and hydrogen content detection. In combination with resistance welding and galvanizing processes, it is found that the fracture mode of the ball pin is intergranular brittle fracture. The reason for the fracture is the presence of local non-fusion in the outer layer of the resistance welding fusion zone and the ineffective hydrogen removal treatment after galvanizing, which led to hydrogen absorption in the welding area, resulting in hydrogen embrittlement fracture. By comparing the hydrogen content before and after heat treatment at 200 ℃ for 2 hours, it is proposed to increase the hydrogen elimination heat treatment process and control the resistance welding process parameters, aiming to avoid similar fracture failure and provide reference for the manufacturing of ball pins.

Key words: Stabilizer bar; Ball pin; Resistance welding; Galvanizition; Hydrogen embrittlement

摘要： 汽车稳定杆是保证车辆行驶平顺性、操纵稳定性、舒适性、安全性及汽车准确行驶的 重要部件。稳定杆球头销一旦发生失效将导致汽车稳定杆整体功能丧失，严重威胁汽车行驶 安全。为确定某 40Cr 汽车稳定杆球头销发生断裂失效原因，对失效球销进行宏观检查、化学 成分分析、金相组织分析、显微维氏硬度测试、断口分析、氢含量检测，结合电阻焊接和镀 锌工艺，进行了综合失效原因分析。结果表明，该球头销的断裂模式为沿晶脆断，断裂原因 为电阻焊熔合区外层存在局部未熔合，镀锌后未能有效消氢处理，导致焊接区发生吸氢，从 而引发氢脆断裂。通过 200 ℃保温消氢 2 h 热处理前后氢含量对比分析，提出增加消氢热处 理工艺并控制电阻焊工艺参数避免类似断裂失效，为球头销制造提供参考。

关键词: 稳定杆；球头销；电阻焊；镀锌；氢脆