Coupled chemo‐electro‐mechanical model for galvanic corrosion in clinched components

Abstract

AbstractMechanical clinching is a frequently used joining method for technical components. These joints are usually weak spots. Here, corrosion and fatigue are decisive influencing factors for the assessment of the service life of such joints. Corrosion generally leads to material deterioration and thus to premature failure of the joints. Under certain circumstances, however, corrosion can lead to an increased fatigue life. While this effect has not yet been fully understood, the present work provides a possible explanation and a modeling approach to predict the fatigue life of precorroded clinched joints. The increased fatigue life is observed when the clinched components are briefly (up to 3 weeks) exposed to a salt spray environment. During this time, a small layer of corrosion products protrudes from the metal surface and fills the gaps between the joined sheets. Due to the increased contact area, the mechanical stress in the joint decreases, resulting in an improved fatigue performance. Although there are a variety of corrosion phenomena, for example, pitting, intergranular, and transgranular corrosion as well as galvanic corrosion, experimental studies indicate that galvanic corrosion is the main contributor of this effect. In the present work, a coupled electro‐chemo‐mechanical corrosion model is presented and applied to two test cases. Case I: corrosion products growth, and Case II: corrosion products growth and mechanical loading.