传动轴管与万向节叉焊接接头断裂分析

汽车传动轴在轴管与万向节叉焊接接头处断裂,通过化学成分分析,焊接接头断口及金相组织观察、硬度分析,确定了焊接接头断裂的模式及产生的原因。结果表明:传动轴管与万向节叉焊接接头为疲劳断裂,疲劳起源于V型焊缝底部万向节叉一侧焊接接头熔合线附近的应力集中部位;万向节叉一侧焊接热影响区的脆性马氏体对疲劳裂纹的萌生和扩展有较大的促进作用;针对焊接接头失效的原因改进了焊接工艺,严控轴管成分,取得了较好的效果。

Fracture Analysis of Welding Joint of Transmission Shaft Tube and Universal Joint Fork

The transmission shaft of a truck fractured at the welding joint of transmission shaft tube and universal joint fork. To find out the fracture mode and causes, the chemical compositions of the transmission shaft tube and the universal joint fork were tested, the fracture surface and microstructure of the welding joint were observed, and the hardness of the welding joint was also tested. The results indicate that the fracture mode of the welding joint of transmission shaft tube and universal joint fork is fatigue fracture. The fatigue crack initiated from the stress concentration zone near the welding fusion line of universal joint fork which is located at the bottom of the V-type weld. The martensite existing at the heat affected zone of universal joint fork accelerated the initiation and propagation of the crack. Based on the fracture cause, the welding technology has been improved and the chemical composition of the transmission shaft tubes has been strictly controls. As a result, the type of failure has been effectively prevented.