Microstructure characteristics of the 2A50 aluminum alloy in radial forging and isothermal treatment conditions

Abstract

A novel recrystallization and partial melting process combined radial forging was proposed to prepare long axial 2A50 aluminum alloy semi-solid billets. Microstructure characteristics of the forged and isothermal treated samples were investigated. Results demonstrate that initial elongated grains (fibrous structure) and low angle grain boundaries were substituted by spherical equiaxed grains and high angle grain boundaries when the sample was heated at 585 °C for 10 min. Deformed textures of the forged 2A50 aluminum alloy were remarkably weaken after isothermal treatment. The average grain size and shape factor increased with the increased temperature and holding time. Long holding time resulted in some dendrites. The liquid films at the grain boundaries thickened with the increase in temperature and holding time. Grains growth and spheroidization were determined by coarsening and Ostwald ripening mechanisms. The coarsening rate constant k of grains at 575 °C was 378.5 μm3/s.