EVALUATION OF CORROSION RESISTANCE OF 6101 ALUMINUM ALLOY AFTER DIFFERENT PRECIPITATION HEAT TREATMENTS

Currently, 6xxx series aluminum alloys have been occupying an important place in the global production of aluminum alloy. Recently, more than 80% of the alloys used in the worldwide production of extruded profiles are made of the Al-Mg-Si. The wide use of this class of alloys is a result of improvement on mechanical properties when subjected to heat treatments. Furthermore, characteristics such as low density, good thermal and electrical conductivity, high reflectivity to light and heat, and corrosion resistance are key factors for the wide applicability of these alloys. The corrosion resistance of alloys in the Al-Mg-Si, is due to the formation of a compact thin film of alumina oxide (Al2O3) which grows naturally on the surface of these alloys under normal atmospheric conditions, protecting the entire surface of material. However, the thermal treatments of solubilization and precipitation of metastable phases during aging may impair the corrosion resistance of this class of alloys. Moreover, the presence of certain corrosive agents, such as chloride and sulfate,can also affect the kinetics of corrosion process. Therefore, the present study aims to evaluate the corrosion behavior of aluminum alloy 6101 subjected to solubilization heat treatment at temperatures of 450°C,480°C,520°C,550°C,580°C and 520°C aged for 5 minutes at 170°C. It was investigated by corrosion tests of weight loss, potential vs time and anodic polarization curves. The the formation of pits was evaluated by scanning electron microscopy(SEM) and optical microscopy. Solutions of 3,5% NaCl and 0,1M Na2SO4 were carried out in order to simulate conditions of high aggressiveness.