汽车拨叉裂纹原因分析

Analysis on Causes for Cracks in a Shifting Fork

采用化学成分分析、硬度检测、金相检测等方法,分析了拨叉裂纹产生的原因。结果表明,拨叉存在缩孔、枝晶间夹渣、偏析,而淬火冷却不足、高频淬火层不均匀、脱碳层、较高的硬度及应力是导致裂纹的原因。

Cracks were found in the castings of gear shifting forks. To study the causes of cracks, chemical analysis, hardness tests and metallographic examinations were carried out. The results show that there are defects such as shrinkage, inter-dendrite slag inclusion and segregation in the shifting fork; and the generation of cracks can be attributed to insufficient cooling during quenching, uneven higher frequency quenching layer, decarburized layer, and relatively high hardness and stress.