  A "through-process" solidification homogenization numerical model to study
the microstructural evolution has been developed for AA7050 alloy. A continuum
scale Direct Chill Casting (DCC) solidification model has been coupled with a
meso-scale homogenization precipitation model to evaluate the radial variation
of microstructure in a cylindrical DC cast billet after homogenization. The
Local Solidification Times predicted by the DCC numerical model is used to
predict the Secondary Dendritic Arm Spacing (SDAS) across the radius from an
empirical relationship. It also predicts the macrosegregation used to estimate
the radial as-cast microstructures (phases and phase fractions) using
Thermo-Calc. Macrosegregation affects the initial and homogenized
microstructures across the radius, making the surface prone to
recrystallization, due to lesser dispersoids and larger precipitated particles
during cooling, caused by lesser extent of Zenner pinning and Particle
Stimulated Nucleation (PSN) of recrystallized grains respectively.
