Corrosion behavior of 6063 aluminum alloys in simulated hot and humid atmospheric environment

Indoor hygrothermal corrosion tests simulated the corrosion behavior of 6063 aluminum alloy in a hygrothermal atmosphere. The corrosion morphology, pitting parameters and surface corrosion products of 6063 aluminum alloy were analyzed by extended depth of field microscopy (EDFM) and X-ray diffractometer (XRD). The evolution of 6063 aluminum alloy's corrosion behavior was studied through corrosion kinetics and electrochemical experiments. It is shown that pitting is the main corrosion form of 6063 aluminum alloy in a simulated hot and humid atmospheric environment. With the extension of corrosion time, the corrosion pits’ depth and width values gradually increase. The pit’s maximum depth and width values could reach 15.75 μm and 101.30 μm, respectively, when the corrosion time is extended to 1 000 h. It can be seen that the corrosion products are mainly composed of Al₂O₃, Al(OH)₃ and Al₂O₃·H₂O. Moreover, the corrosion weight loss of 6063 aluminum alloy follows a power-law relationship with the corrosion time in a simulated hot and humid atmosphere. The corrosion rate decreases as the corrosion time increases. Analysis of electrochemical impedance and polarization curves indicates the corrosion product layer provides a specific protective effect. In addition, the tensile and yield strength of 6063 aluminum alloy decreased by 7.74% and 8.88% respectively after 1 000 hours of hygrothermal corrosion.