花键轴断裂分析

Analysis on Spline Shaft Fracturing

某20CrMnTi钢花键轴在使用约2个月时发生断裂。对断裂的花键轴进行了宏观检查、显微组织观察和硬度测试,以揭示花键轴断裂的原因。结果表明,花键轴的断裂为疲劳断裂,疲劳源产生在花键轴台阶圆角处。这是由于焊接热产生了脆性的马氏体,致使花键轴台阶圆角处的疲劳抗力降低,引发疲劳裂纹并导致断裂。

A type of spline shaft,made of 20 CrMnTi steel,fractured when serviced for about up to two months.The fractured spline shaft was subjected to visual check,microstructure observation and hardness measurements to reveal the reason why the spline shaft fractured.The results indicate that the spline shaft fracturing is a fatigue failure originating from the spline shaft step corner where brittle martensite forms due to weld heat,and renders its resistance to fatigue lower,thus developing fatigue crack and causing the spline shaft to fracture.