20CrMnMo减速机高速轴断裂原因分析

某工程用20CrMnMo减速机高速轴在试运行过程中轴杆变截面处发生断裂。对高速轴进行宏观、微观断口分析，显微组织分析，力学性能测试等。结果表明：该高速轴的断裂形式为旋转疲劳断裂，轴表面的机加工损伤是导致其早期疲劳断裂的直接原因。热处理工艺不当造成的混晶和硬度偏低促进了裂纹的萌生，在服役过程中变截面位置应力集中，导致高速轴受交变载荷作用而发生断裂。

Fracture analysis of the causes of high speed shaft of 20CrMnMo reducer

The high speed shaft of a 20CrMnMo reducer used in a project broke during the trial run at the shaft cross section. The high speed shaft was tested by macro and micro fracture analysis, micro structure analysis and mechanical property test. The results show that the fracture form of this high speed shaft was rotation fatigue fracture, and the machining damage on the shaft surface was the direct cause of its early fatigue fracture. The mixed crystal and the low hardness caused by improper heat treatment process promoted the initiation of cracks. During service, the stress concentration at the machining damage caused the fracture of high speed shaft due to the alternating load.