Electrochemical Properties of Heat-Treated Al Alloy A6061-T6 in 0.5 M H 2 SO 4 Solution

The present study investigated the effects of heat treatment by low-temperature annealing and temperature change on the electrochemical properties of aluminium (Al) alloy A6061-T6 in 0.5 M sulphuric acid (H 2 SO 4 ) solution. Subsequent to heat treatment at five different temperatures of 250 °C, 300 °C, 350 °C, 400 °C, and 500 °C (constant time of 1 h.), the heat-treated Al alloy A6061-T6 samples were subjected to corrosion tests via potentiodynamic polarization techniques at room temperature. Optical microscopy was used for the characterization of the corroded areas for both the control and heat-treated samples. Compared to the control Al alloy A6061-T6 sample with a higher corrosion current density of 391.38 µA/cm 2 , the Al alloy A6061-T6 samples annealed at 250 °C, 300 °C, 350 °C, 400 °C, and 450 °C possessed a lower corrosion current density of 390.62 µA/cm 2 , 191.66 µA/cm 2 , 113.89 µA/cm 2 , 64.23 µA/cm 2 , and 60.99 µA/cm 2 , respectively. The annealed samples are characterized by lower corrosion density as well as the presence of little or no corrosion products and pits. Heat treatment by low-temperature annealing improves the electrochemical properties of Al alloy A6061-T6, and the corrosion resistance increases with increasing annealing temperature.