Effects of temperature and time on three-dimensional microstructural evolution of semi-solid 2A14 aluminum alloy during short process preparation of semi-solid billets

Abstract

To shorten the preparation process of semi-solid billets, semi-solid billets of 2A14 aluminum alloy were prepared by wrought aluminum directly semi-solid isothermal treatment (WADSSIT) process. Three-dimension (3D) combined microstructure evolution, namely transverse direction (TD) surface, rolling direction (RD) surface, and normal direction (ND) surface, was studied. Effects of temperature and holding time on average grain size and average shape factor were investigated. The results showed that the optimum conditions for preparation of 2A14 semi-solid billets by this process were 615 °C and 20 min (average grain size of 124 μm and shape factor of 0.81). Electron backscatter diffraction (EBSD) observations indicated that the microstructure was completely recrystallized when it was heated to 600 °C. Grain size was increased with the increase of temperature and grew up slowly with the holding time prolonging. Roundness was increased with increase of holding time but was not sensitive to temperature.