某柴油机传动轴裂纹的失效分析

Failure Analysis of A Diesel Engine Transmission Shaft Cracks

某柴油机42CrMoH钢传动轴在经锻造-正火-粗加工-UT探伤-调质-精加工等工步后,在法兰盘处发现裂纹。本文简要介绍了该轴锻造工艺及设备,并对该裂纹的形成原因通过金相显微镜与电子显微镜进行分析。结果表明,裂纹的产生是由于原材料中的C及S元素超标,导致成分偏析,使MnS及Fe3C在晶界处聚集造成的,此外局部位置又有铸造组织。

The 42 CrMoH steel drive shaft of a diesel engine produces cracks at the flange after forging-normalizing-rough machining-UT flaw detection-quenching and tempering treatment and finishing. The forging process and equipment of the shaft were briefly introduced, and the formation of the crack was analyzed by metallographic microscope and electron microscope. The results show that the crack is caused by the excess of the C and S elements in the raw materials, which leads to the segregation of components, the aggregation of MnS and Fe3C at the grain boundary, and the local position has casting structure.