目的 分析汽车机油冷却器的典型缺陷，寻找其产生的根本原因，制定相应的措施，从而避免此类问题的再次发生。方法 通过对失效车辆的分布进行统计分析，锁定失效车辆的范围。使用扫描电子显微镜对失效部位的微观结构进行观察，通过能谱仪对腐蚀部位周围的腐蚀产物进行分析，发现其主要成分为Al2O3，并且发现了Cl?。结合前人的腐蚀理论，并对比分析，确定腐蚀主要是由于Cl?的穿透作用导致的孔蚀。通过对防冻液进行统计分析，并对当时防冻液样品中Cl?的含量进行检测，确定腐蚀元素的来源为防冻液。通过分析防冻液的混合工艺，现场检查油库的应急操作，并且进行模拟实验，可以确定由于油库人员的操作不当导致消毒液中的Cl?被大量引入储水罐的混合用水中，最终使加注的防冻液带有强烈的腐蚀性。结果 防冻液的混合用水中Cl?的含量远高于正常水平。结论 防冻液的混合用水中Cl?含量过高，导致铝合金表面钝化膜被穿透，最终形成了典型的铝合金孔蚀失效。

The work aims to analyze typical defects of automotive automotive oil cooler, find root cause and make corresponding measures to prevent such problems from occurring repeatedly. Scope of faulty vehicles was defined by performing statistical analysis to distribution of the faulty vehicles. Microstructure of faulty position was observed with SEM, corrosion products around were analyzed with EDX and found to be mainly aluminum oxide, and chloride ions were also found. Allowing for previous corrosion theories and contrastive analysis, the corrosion was found to be mainly caused by penetration effect of chloride ions. According to statistical analysis of antifreeze and content measurement of chlorides ions in the antifreeze samples, the corrosion elements came from the coolant fluid. Based on analysis of mixing process, field inspection of depot emergency operation and simulation experiment, it could be determined that chloride ions in disinfectant were introduced into the mixing water in water storage tank in quantity due to improper operation by depot staff. As a result, the antifreeze was highly corrosive. The Cl? content in mixing water samples to be mixed with the antifreeze was considerably higher than normal level. Too high Cl? content in mixing water leads to penetration of passive film on the aluminum alloy, and causes a typical pitting failure of aluminum alloy finally.