Failure Analysis on Fracture of an Automobile Lever in Transmission

By means of macroscopic inspection, chemical composition analysis, metallographic examination, hardness test, scanning electron microscope analysis and energy spectrum analysis, the fracture reasons of an automobile lever in transmission were analyzed. The results show that the fracture of the lever was caused by too much stamping force from stamping process which would result in micro cracks around the stamping hole. When shifting the gear in transmission, the lever would be forced and the micro cracks would propagate, which finally induced fracture of the lever.