Optimizing Thermal Processing of Additively Manufactured 7050-based Aluminum Alloy for High Corrosion Resistance

Al-Mg-Zn-Cu based high-strength aluminum alloys fabricated via laser powder bed fusion (LPBF) process are highly promising candidates for aerospace applications owing to the inherent benefits of AA 7050 alloys like high strength to weight ratio and good corrosion performance. Recent developments in inoculation and nano-particle addition have demonstrated equiaxed grain growth, mitigating the issues of solidification defects and periodic cracks in the final microstructure, formed during the LPBF process. In this work, we systematically study the effect of different thermal processing treatments such as stress relieving, HIPing, solutionizing and ageing on the microstructure of an AM 7050-based aluminum alloy with an equiaxed microstructure with minimal defects. AM 7050-based aluminum alloy needs a separate optimization of the thermal processing than the traditional AA 7050 alloy. The corrosion resistance of AM 7050-based aluminum alloy is studied and compared with an equivalent wrought alloy for different combinations of thermal processing, giving insights on the optimized process windows to be followed for AM 7050-based alloy for high corrosion resistance.