Premature fracture of high-strength suspension springs caused by corrosion fatigue cracking

Abstract

In this work, the mechanisms responsible for the premature fatigue fracture of four suspension springs during road test were investigated. Failure analysis combined with finite element method (FEM) and stress corrosion cracking (SCC) experiments were conducted. The results indicate that the corrosion and wear damage occur on the failed spring surface caused by the stone chipping and acid rain. The unexpected failure of suspension springs was caused by the presence of surface cracks formed by the corrosion fatigue cracking (CFC) mechanism. The fatigue strength of spring reduces to as low as 420 MPa due to the presence of these surface cracks, which is much lower than the service stress. As a result, the fatigue crack propagates quickly without the help of corrosion and leading to the final rupture.