Fracture Analysis of End Shaft of a Forklift Axle Housing

The end axle of a forklift axle housing fractured after 1 000 h of use, and the fracture, chemical compositions, mechanical properties, microstructure of the fractured part were analyzed to identify the fracture reasons. The results show that the fracture of the end axle was fatigue fracture. Small fillet radius and evident machining marks at the fracture position resulted in serious stress concentration here. In addition, Due to the improper control of the heat treatment process, the microstructure of the material was seriously uneven and large internal stress was produced. On the other hand, the mechanical properties and the fatigue strength of the material decreased greatly because of no quenching and tempering treatment. The above mentioned factors were the main causes for the fatigue fracture of the end shaft of the forklift axle housing.