Long-term Corrosion Studies of a CFRP/EN AW-6060-T6 Self-piercing rivet Joint and a Steel/EN AW-6060-T6 Blind Rivet Joint

Abstract

The corrosion behaviour of the aluminium alloy EN AW-6060-T6 in a self-piercing rivet joint and in a blind rivet joint was investigated by the VDA 621-415 climate chamber test for multiple corrosion cycles. After each cycle the aluminium alloy was analysed in the most damaged region that was found close to the overlap of the joints. The time-dependent damage evolution was evaluated by interferometry involving a subsequent pit volume calculation. Moreover, the potentiodynamic polarisation behaviour of each joint component was analysed in the 5wt.% sodium chloride solution which is used in the salt spray test during the test according to VDA 621-415. By graphic explorations of the polarisation curves, the galvanic corrosion characteristics were examined and the pitting corrosion susceptibility of the aluminium alloy in the joints was evaluated. It was found, that the results of the graphically data extraction correlate to the corrosion behaviour during the long-term exposure test for both joints. Moreover, the pit volume - cycle number relation exhibited a stepwise damage behaviour of the aluminium alloy in the blind rivet joint. After the end of the climate chamber tests the aluminium alloy in the blind rivet joint revealed stronger corrosion damage in less exposure time than in the self-piercing rivet joint.