发动机传动轴齿轮断裂失效分析

某发动机累计工作66min后,传动轴齿轮上有两个齿发生了断裂,与其相配合的片齿轮未发现任何损伤.对传动轴齿轮和片齿轮的齿形、齿向进行了检测,结果表明,传动轴齿轮和片齿轮的齿形和齿向参数符合技术要求.对传动轴断齿的宏微观特征进行了观察与分析,并对传动轴和片齿轮的渗层深度、金相组织进行了检测.结果表明,传动轴断齿的断裂性质为疲劳断裂,传动轴齿表面硬度偏低和片齿轮表面硬度偏高导致传动轴齿表面接触疲劳剥落,传动轴齿轮表面渗层出现的连续网状氮化物是促进其疲劳断裂的又一个影响因素.建议完善传动轴和片齿轮的表面处理工艺参数,加强控制工艺过程.

Fracture Failure Analysis of Transmission Shaft Gear of an Engine

Two teeth on the transmission shaft gear of an engine fractured after servicing for 66 minutes,while there is no damage on the matched sheet gear.The teeth shape and direction of the transmission shaft gear and the sheet gear were inspected,the result showed that the teeth shape and direction were accorded with the request.The macroscopical and microscopical fracture characteristics of the transmission shaft gear were observed.The depth of the nitriding layer and the metallographic structure of the transmission shaft and the sheet gear were also measured. The test results show that the fracture mode is fatigue. The main cause of contact fatigue is that the surface hardness of the transmission shaft was low while the surface hardness of the matching sheet gear was too high, the continuous netty nitride in the exudant layer on the surface of the transmission shaft gear is another factor induced the fatigue. We recommend to perfect the nitriding process parameters of both the transmission shaft gear and the matching gear.