Quantitative Study on the Correlation Between Microstructure and Mechanical Properties of Additive Friction Stir Deposited 6061-T6 Al-Mg-Si Alloy

Additive friction stir deposition (AFSD) technology is attractive for its ability to create freeform and fully dense structures without melting and solidification. Hence, AFSD is an alternative to fusion-based additive manufacturing technology. However, the quantitative relationship between mechanical properties and microstructure has not been established yet. The purpose of the research is to establish a quantitative relationship between the microstructure and mechanical properties of AFSD-ed 6061-T6 aluminum alloy. In this study, 6061-T6 aluminum alloy feedstock was processed using AFSD technology and then subjected to post-deposited heat treatment (PDHT). The microstructure evolution and mechanical properties of the feedstock, as-deposited and PDHT-ed 6061-T6 aluminum alloy specimens, were investigated for a comparative study. The microstructure was analyzed using electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Hardness testing and tensile testing were conducted for the feedstock, as-deposited, and PDHT-ed specimens. The strengthening mechanisms were discussed. It was found that precipitation strengthening was the main strengthening mechanism for feedstock and PDHT-ed specimens, which contributed to 69% and 83% of the total yield strength, respectively. Whereas grain refinement strengthening was the main strengthening mechanism for the as-deposited specimen, which occupied 68% of the total yield strength. Finally, the relationship between microstructure and mechanical properties of additive friction stirdeposited 6061-T6 Al-Mg-Si alloy was quantified. & COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).