某厂生产的钢板弹簧在台架疲劳试验中发生早期断裂失效。通过宏观分析、断口扫描电镜及能谱分析、金相检验等方法对钢板弹簧的断裂原因进行了分析。结果表明：钢板弹簧断裂为早期疲劳断裂，断裂起源于钢板表层夹渣缺陷；夹渣主要为外来夹杂物，大多来自钢液与大包、中包、水口等接触产生的二次氧化物，也包括脱氧产物上浮不充分；通过在转炉冶炼时由低拉碳出钢转变为高拉碳出钢，精炼过程中采用石灰等碳含量较高的脱氧剂，转炉内采用铝、硅等强脱氧剂等工艺的实施，有效地避免了由于弹簧扁钢夹渣缺陷导致钢板弹簧早期断裂失效的发生。

Early fracture failure happened to a leaf spring produced by a factory during the bench fatigue test. The fracture causes of the leaf spring were analyzed by macroscopic analysis, scanning electron microscopy and energy spectrum analysis, and metallographic examination. The results show that the fracture of the leaf spring was early fatigue fracture, and the fracture originated from the slag defect in the steel plate surface. The slags are mainly foreign inclusions, and they are mostly from the secondary oxide of molten steel when contacting with the ladles, tundishes and nozzles, including the deoxidation products which were not fully floated. By adopting measures such as converting low carbon catching to high carbon catching during converter smelting, using deoxidizing agents with a high carbon content such as lime during refining, and using a strong deoxidizer such as aluminum or silicon in the converter, the early fracture failure of the leaf spring due to the slag defect in the spring flat steel was effectively avoided.