Effect of Equal-Channel Angular Pressing Passes on the Corrosion Behavior of 1050 Aluminum Alloy in Natural Seawater

In this work, the 1050 aluminum alloy (AA 1050) was processed by using equal-channel angular pressing (ECAP) technique for different number of passes namely; 0, 4, 6, 8, 12 and 16 passes. The effect of ECAP passes on the corrosion behavior of AA 1050 in Arabian Gulf seawater (AGS) has been investigated. Cyclic potentiodynamic polarization (CPP), chronoamperometric current-time (CT), and electrochemical impedance spectroscopy (EIS) measurements for AA 1050 after 20 min and 10 days immersion in the AGS solutions were carried out at room temperature. Polarization curves and chronoamperometric experiments at -0.63 V vs. Ag/AgCl indicated that the ECAPed AA 1050 shows lower corrosion current density, higher corrosion resistance and less corrosion rate compared to the unprocessed (annealed) alloy and the best performance for the alloy was obtained after 4 passes. EIS spectra confirmed the data obtained by CPP and CT measurements that the ECAPed AA 1050 alloy showed a lower corrosion rate and higher surface and polarization resistances; this effect changes in the order of 4 > 6 > 8 > 12 > 16 > 0 passes. This effect increases also with increasing the immersion time of AA 1050 in the AGS solution from 20 min to 10 days.