某车桥止推垫片断裂失效分析

Failure analysis on the stub thrust washer of an electric axle

  • 摘要: 对不同厂家脆断止推垫片的化学成分、断口金相组织、硬度、断口宏观与微观形貌、垫片断裂模式以及表面渗碳层等方面进行对比分析。结果表明:该失效止推垫片脆性断裂的主要原因为淬火温度低,存在隐晶马氏体+块状铁素体的复相组织,急剧降低了心部的冲击韧度,在冲击作用下,止推垫片心部沿着隐晶马氏体迅速扩展。渗碳后将淬火温度提高到840℃左右,提高了止推垫片心部的冲击韧度,同时减小垫片有效硬化层深,降低其表层脆性,杜绝了垫片脆性断裂的发生。

     

    Abstract: The chemical composition, fracture microstructure, hardness, fracture morphology, fracture mode and surface carburizing layer of brittle thrust gaskets from different manufacturers are compared and analyzed. The results show that cryptocrystalline martensite and granular ferrite duplex structure appeared at low quenching temperature reduced the toughness of washer core zone, causing crack growth and propagation under impact. To avoid the brittle fracture of thrust washer, impact toughness of core zone is increased by raising the quenching temperature to near +840℃, and the surface brittleness is reduced by decreasing case hardening depth.

     

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