Semi-solid processing of the primary aluminium die casting alloy A365

Abstract

A365 (AlSi9MgMn) is a primary die casting alloy widely used to manufacture automotive parts. Low superheat casting with and without a cooling plate was employed in the present work to produce A365 thixoforming feedstock. The dendritic features were more frequent in the latter, suggesting that the degeneration of the dendritic structure was promoted by casting over the cooling plate. It was possible to thixoform the non-dendritic A365 feedstock into a simple part after it was held at 580 °C for 5 min. The thixoforming process was very challenging, however, since even the slightest deviation from 580 °C has either led to shape distortion of the slug or degraded its thixoformability, resulting in incomplete die filling in both cases. Once thixoformed, the A365 part attained hardness values as high as 84 HB after T6 heat treatment.