Effect of galvanic corrosion on durability of aluminium/steel self-piercing rivet joints

Galvanic corrosion of steel/aluminium hybrid joints, obtained by self-piercing riveting technique, was investigated. Potentiodynamic polarisation tests, performed in 3.5 wt-% NaCl solution, evidenced the anodic and cathodic behaviour of metal constituent of the joints. Furthermore, long term aging tests were performed to evaluate the relationship among failure mechanism, joint configuration and corrosion damage in salt spray environment. The experimental results evidenced that the degradation phenomena influenced significantly performances and failure mechanisms of the joints, inducing premature failure of the joint at lower stress level at increasing aging time. Furthermore a theoretical model was proposed to forecast failure modes. Based on this model a simplified map of failure mechanisms promoted by corrosion phenomena has been drawn.