Effect of Heat Treatment on the Corrosion Behavior of AA6061 Aluminum Alloy in Highly Acidic Media

This study investigated the effect of heat treatment on the corrosion behavior of commercially purchased AA6061 aluminum alloy in highly acidic media. The alloys were subjected to three heat treatment conditions: solution heat treatment (homogenization), precipitation hardening (artificial aging), and annealing, with as-received samples serving as baseline. Corrosion behaviors were evaluated using the gravimetric weight loss method in 0.1M H₂SO₄ solution fpr 168 hours. Microstructural analysis were performed on the samples using optical microscopy before and after corrosion testing to state the type of corrosion associated with each processes. Results revealed that the as-received (non-heat treated) samples exhibited the best corrosion resistance with an average corrosion rate of 1.049 mm/yr. Precipitation hardening showed improved resistance (1.291 mm/yr) compared to solution heat treatment (1.554 mm/yr) and annealing (1.750 mm/yr). The high corrosion resistance of the heat-treated samples were attributed to elevated iron (0.72%) and lead (0.34%) impurities that formed cathodic intermetallic particles and segregated at grain boundaries. Pitting corrosion was the dominant mechanism in acidic media, with intergranular corrosion observed in heat-treated samples. The study established that non-heat treated AA6061 provides optimal corrosion resistance in highly acidic environments.

AA6061, heat treatment, corrosion, acidic media

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