排气阀杆锁夹槽断裂分析及机理研究  

Theoretical Study and Failure Analysis of Valve Rod Slot Fracture

作　　者：倪兆荣[1] 李志章[2] 郑一平[1] 

机构地区：[1]金华职业技术学院机电工程学院 [2]浙江大学材料与化学工程学院

出　　处：《农业机械学报》2004年第5期208-211,共4页Transactions of the Chinese Society for Agricultural Machinery

摘　　要：在分析断裂排气阀杆用材成分、冶金质量、金相组织及热处理工艺后 ,对断口宏观、微观形貌进行观察 ,结果表明 ,该阀杆锁夹槽断裂是由于其结构尺寸不合理及表面存在脆性氮化物层 ,在高频率 (40 0 0次 / min)强冲击应力作用下 ,锁夹槽颈缩处形成严重的能量集中、表面应力集中 ,致使表面氮化层崩裂 ,沿圆周形成多个裂纹源 ,并迅速向心部扇形扩展 ,最终导致断裂 ,并在断口上出现与高频率强冲击拉伸载荷相应的特殊形貌的 2次裂纹。It is concluded that the main reasons for the fracture of a slot were those the frame dimension on the slot was irrationality and there was brittle nitride layer on the surface of the slot by examining the chemical composition of a valve rod slot and analyzing the macroscopic and microscopic appearances of the fracture. Under a strong and high frequency (4000 times/min) impact stress, a serious energy and surface stress concentrations will be formed at the shrinkage neck, which lead to breakup along multi crack fountains in circle. These breakups spread quickly from fountains to sector in center, and finally rupture. Moreover secondary cracks with special appearance were observed in fracture after strong and high frequency impact stretching load.

关 键 词：排气阀杆 锁夹槽 断裂分析 冶金质量 金相组织 摩托车 

分 类 号：TK413.4[动力工程及工程热物理—动力机械及工程] U483[交通运输工程—载运工具运用工程]