Microstructural evolution in twin roll cast AA3105 during homogenization

In twin roll cast (TRC) AA3105, high solidification and post-solidification cooling rates lead to high manganese supersaturation throughout the strip and very fine constituent particles near the surface. Rolled and annealed TRC material shows sluggish recrystallization kinetics and a very coarse grain structure, due to concurrent dispersoid precipitation that inhibits formation of recrystallization nuclei. Homogenization from 5 to 120 h at 600 °C reduced solute supersaturation and coarsened constituent particles, reducing but not eliminating the particle size gradient. The resulting grain structure was fine throughout most of the strip, but with larger grains at the surface. More extensive cyclical homogenization up to 620 °C further coarsened the constituent particles and produced a uniform fine grain structure throughout the strip.