某自卸车前桥在使用过程中断裂。采用宏、微观检验、力学性能测试以及化学成分分析等方法对断裂前桥进行了分析。检验结果表明,前桥的断裂属于脆性断裂,断裂起源于前桥工字梁前侧焊接处。由于在前桥上焊接钢带时,在焊接热影响区产生了高硬度的马氏体和焊接裂纹,从而导致前桥受力时产生脆性断裂。

The front axle of a dump truck broke in service. The chemical composition,microstructure and fractography of the failure axle were analyzed. The results indicated that it was a brittle fracture,and the fracture occured in the weld point on the axle where the steel belt was welded on. The high hardness martensite and the welded crack had been found in the weld point and which caused the brittle fracture of the front axle.