Effect of Cold Rolling Reduction Rate on Corrosion Behaviour of Twin-roll Cast 8006 Aluminium Alloys

Abstract

Utilization of aluminum alloys in the automotive industry takes a crucial role in recent years due to their excellent properties such as corrosion resistance and light weight. 3003 and 8006 aluminum alloys have been particularly used as a heat exchanger compartment due to their corrosion resistance feature which has a perfect match for a heat exchanger fin stocks and a destructive salty environment in this car's part. In the present work, an effect of cold rolling reduction (CRR) rate on the corrosion twin-roll cast 8006 aluminium alloys was investigated. Firstly, the aluminium alloy was submitted to twin-roll casting process to achieve 8.5 mm thickness sheet. Then, homogenization annealing was applied between 550 °C and 600 °C. Subsequently, two cold rolling routes were subjected at different CRR rates of 94% and 98%, respectively. Finally, the aluminium sheets were annealed between 400 °C and 450 °C for 60 min. in a furnace for electrochemical corrosion tests. Electrochemical corrosion tests were performed in 1 M NaCl and H2O2 solution, and open circuit potential and polarization curves were successfully achieved. The surface features of the specimens before and after corrosion tests were assessed using stereomicroscopy and 3D profilometer. Based on the results, an increase in the various CRR rates depending on cold rolling route applied decreases the corrosion resistance of the twin-roll cast 8006 aluminum alloys. Thus, they could be very versatile materials for heat exchanger fin stock materials.