Microstructure and mechanical property evolution of CFRP/Al electromagnetic riveted lap joint in a severe condition

Abstract

This paper investigated the microstructure and mechanical property evolution of CFRP/Al electromagnetic riveted structures exposed at a neutral salt spray environment. Electrochemical tests, microstructure observations, weight measurements and mechanical property tests were conducted. The observed results showed that corrosion pits on Al sheet were mainly located at the edge of the overlapping area due to the galvanic and crevice corrosion. Beside, visible cracks were observed on the surface of CFRP sheets after 3 weeks ageing. Maximum pit depth and weight evolution showed that the corrosion rate after the ageing time of 1 week was the fastest. The reason was that the corrosion products existed in pit and clearance effectively prevented oxygen and water contacting with Al matrix, which led to a decrease in the subsequent corrosion rate. The mechanical property tests results showed that the maximum shear loads after the ageing time of 1 week dropped the quickest due to faster corrosion rate at this stage. In addition, at the ageing time of 1 to 7 weeks, the maximum shear load after the ageing time of 3 weeks decreased faster. This was due to the surface of CFRP sheet was obviously damaged after the ageing time of 3 weeks, which further reduced the joint strength. In general, this work is expected to deeply understand the corrosion characteristics of the CFRP/Al electromagnetic riveted joints in engineering application.