Failure Analysis on Fracture of Vehicle Stable Bar in Durability Test

A new developed SUP9 steel solid stable bar fractured and failed in the process of durability test. The failure causes of the stable bar were analyzed by means of fracture analysis, chemical composition analysis, hardness test and metallographic examination. The results show that the fracture of the failure stable bar was a typical fatigue erack fracture. There was a serious decarburization problem in the stable bar, which led to the early fatigue crack initiated and expanded of the stable bar, and finally to fatigue fracture failure of the stable bar.