A numerical model for the grain refinements of the aluminium alloys automobile wheel

Based on the traditional solidification mechanism, a numerical model for the new grain refinements of the aluminium alloys of an automobile wheel has been established. It is assumed that the constitutional undercooling generated by the growth of a grain is equivalent to the undercooling required for nucleation of another adjacent grain; and the distance between nucleation events is defined as the relative grain size in the final microstructure; the negative thermal gradient and the latent heat at the grain-liquid interface are negligible in comparison to the amount of constitutional undercooling; the thermal physical parameters are fixed. On the basis of numerical model results, the constitutional undercooling and the relative grain size of the grain refinements have been calculated. The nucleation undercooling of the new grain is about 0.5-1.0 K, which is lower than traditional aluminium alloys by 0.3-0.5 K. The numerical model results can be used to investigate the grain refinement mechanism, and the new grain refinements can be used to produce aluminium alloys automobile wheel