Microstructure and mechanical properties of semi-solid modified 6061 aluminum alloy rheological die-casting specimens

(1) The composite rheological die-casting process of serpentine channel casting can effectively improve the as-cast structure of 6061 aluminum alloy. The primary α-Al grains evolve from coarse dendrites to small, rounded globular crystals or nearly globular crystals.
(2) Increasing the Si content can significantly refine the structure of the semi-solid modified 6061 aluminum alloy rheological die-casting sample. As the Si content increases, the average grain diameter of primary α-Al in the rheological die-casting sample structure gradually decreases. When the Si content increases from 0.6% to 2.6%, the diameter of primary α-Al grains in the edge structure increases. The average grain diameter gradually decreased from 52 μm to 32 μm; the average grain diameter of primary α-Al grains in the core structure gradually decreased from 64 μm to 34 μm.
(3) Under the same Si content, semi-solid modified 6061 aluminum alloy rheological die-casting samples show better mechanical properties than traditional liquid die-casting samples. When the Si content increases from 0.6% to 2.6%, the as-cast tensile strength of the semi-solid modified 6061 aluminum alloy rheological die-casting sample gradually increases from (107±4) MPa to (209±14) MPa. The length rate gradually increased from 2.2%±0.3% to 5.5%±0.5%.