The Influence of Shot Peening and Artificially Ageing Aluminium Alloy 7075 on Corrosion Behaviour

This paper investigates the corrosion of shot peened AA7075 aluminium alloys aged at different temperatures. The surface integrity of the hardened layer was evaluated with SEM, EDS, differential scanning calorimetry, hardness, and roughness measurements, and in the end also with corrosion resistance tests. The research results indicated that there were significant differences in precipitates distribution between aluminium alloys artificially aged at different temperatures. As the ageing temperature increases, the microhardness decreases, which influences the final roughness condition of the surface layer after shot peening. The results of potentiodynamic polarisation tests indicate that shot peening enables shifting the pitting potential to positive values, which ensures slightly higher corrosion resistance. SEM images confirmed the dissolution of the aluminium matrix near the separated iron-rich phases of the Al_x form (Fe, Mn) by the action of galvanic cells.