Effect of Zr particles and RRA heat treatment on properties and grain boundary precipitation of ۷۰۵۵ Aluminum alloys

Due to its high strength and corrosion resistance, aluminum alloy ۷۰۵۵ is widely used in aerospace structures. However, its susceptibility to stress corrosion cracking (SCC) limits its performance. In this study, the combined effects of zirconium (Zr) addition and retrogression and re-aging (RRA) heat treatment on the microstructure, grain boundary precipitates, and stress corrosion resistance (SCR) of ۷۰۵۵ aluminum alloy were investigated. For property evaluation, microstructural characterization was carried out using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), while mechanical and stress corrosion tests were conducted according to ASTM standards. The results showed that Zr addition refined the grains and promoted the formation of Al۳Zr particles within the matrix, inhibiting grain growth during heat treatment. RRA treatment accompanied by Zr addition improved the mechanical strength from ۵۲۸ to ۶۰۸ MPa and increased the stress corrosion resistance from ۶۸ to ۹۶ %. The combined effect of Zr addition and RRA treatment resulted in a more stable microstructure, with improved strength and resistance to stress-corrosion cracking.

کلیدواژه ها:

۷۰۵۵ Al Treatment ، Zr in Al Grain boundary ، Al ۷۰۵۵ Corrosion ، Zr in Al ۷۰۵۵