Cause Analysis on Fracture Failure of Drag Chains of Aerial Power and Free Push Type Suspension Conveyer

Two drag chains of aerial power and free push type suspension conveyer in an automotive welding workshop fractured during applications. One of the drag chains fractured on both sides after using 1 a (annum) time, the other fractured on one side after using 10 a time. The failure fracture reasons were analyzed by methods of macroscopic observation, chemical composition analysis, hardness test, metallographic examination, macro and micro fracture morphology analysis. The results show that the 1 a failure part overload fractured caused by fatigue and unequal stress; the fatigue expansion area almost completely covers the whole fracture of 10 a failure parts, which was fatigue fracture.