Study on Corrosion Behavior of 7075 Aluminum Alloy with Retrogression and Reaging Using Taguchi Method

摘要

The corrosion resistance and mechanical properties of 7075 aluminum alloy are improved by retrogression and reaging (RRA) heat treatment. Due to the complex process of RRA heat treatment, a Taguchi L25 orthogonal array is designed to optimize the process parameters of RRA heat treatment. In this work, analysis of variance was performed to find out the significant heat treatment parameters. Microstructure, mechanical properties, intergranular corrosion, exfoliation corrosion and stress corrosion cracking behaviors of 7075 aluminum alloy after RRA heat treatment were investigated by tensile test, slow strain rate test, transmission electron microscope and scanning electron microscope. Results showed that the RRA treatment involving preaging at 120 degrees C for 16h, retrogression at 200 degrees C for 8min and reaging at 120 degrees C for 24h resulted in a desired combination of corrosion resistance and mechanical properties.