三挡同步器齿环开裂原因分析

Third Gear Synchronizer Ring Crack Reason Analysis

针对三挡同步器齿环装车后启动时发现开裂的问题,为查明其开裂原因,通过化学成分分析、硬度测试、裂纹宏观和微观金相检验等试验对开裂齿环进行了分析。结果表明:同步器齿环的开裂是由于凹槽在冷挤压时产生的形变应力和装配不当引起的外加应力,加上汽车停放在含有腐蚀介质(主要是氨或二氧化硫)、氧及潮湿空气中,即为拉应力和腐蚀介质共同作用下产生的应力腐蚀裂纹。

Third gear synchronizer ring loading after initiation of cracking was found. To identify the cau- ses of cracking, by chemical composition analysis, hardness test, crack macroscopic and microcosmic met- allographic examination test of crack gear ring are analyzed. The results show that： the cracking due to groove in cold extrusion is produced when the deformation stress and i caused by applied stress, and car park in contains corrosive medium （mainly ammoni ide） , oxygen and moisture in the air, is the tensile stress and corrosion medium under t of the stress corrosion crack.