采用直读光谱仪、显微硬度计、光学显微镜、扫描电子显微镜等分析手段,对失效弹簧座的开裂原因进行了分析.结果表明:弹簧座失效的内因是热处理回火不够充分,使材料硬度偏高、脆性增加；夹杂物和碳化物带状级别较高造成材料组织和性能的均匀性变差,形成微区应力集中,且磨削工艺不当导致弹簧座在磨削过程中产生了磨削裂纹；其外因是在装配采用敲击方法,力量难以控制,结果使弹簧座在试运行过程中于应力集中严重的磨削裂纹处起裂并最终开裂;针对此原因提出了该弹簧座开裂失效的改进措施并取得了显著效果.

Means of optical emission spectrometer,microhardness tester,optical microscope,scanning electronic microscope were used to analyze craking reason of the failure spring seat.The results showed that the cracked spring seat was under tempering,which resulted in the high hardness and brittleness of the material.Inclusions and banded carbides level were both high and made the homogeneity of microstructure and properties became worse and stress concentration were formed at micro-region.Grinding cracks were produced because of the improper grinding process.In addition,the spring seat was assembled by strock methods and the force was difficult to controll.All above factors coacted and caused the spring seat cracked from the grinding cracks with serious stress concentration.Improvement measures were proposed and remarkable results were achieved.