Fracture Reason Analysis of an Axial Gear

An axial gear fractured which serviced only for one month and the fracture reason was analyzed by chemical compositions analysis, fracture analysis, metallographic examination and hardness test. The results show that the fracture located at the arc transition of 80 mm and 165 mm of the axial gear. Repair welding was done to the axial gear at the arc transition because dimensional deviation appeared at this position when it was finish machined, which result in the formation of large interior stress and many micro cracks at the surface of the axial gear. At the same time the arc transition was also the stress concentration position. Under the action of operation stress, the formed cracks expanded rapidly and led to final fracture of the axial gear.