Estimation of Solid Solution Si Concentration in Al–Si Alloy Castings Based on Dimensional Change during Heat Treatment

Abstract

Solid solution elements in the α-Al phase affect the dimensional precisions under high temperature circumstances and the mechanical properties of Al–Si alloy castings. However, there is insufficient information on the concentration of the solid solution elements in as-cast castings. In this study, we examined the possibility of estimating the concentration of the solid solution silicon in the α-Al phases of permanent mold cast Al–Si alloy castings using a theoretical model related to the concentration of the solid solution silicon and the dimensional change arising from heat treatment. Al–1%Si and Al–10%Si alloy castings containing 1.00% and 1.06% solid solution silicon in the α-Al phases, respectively, were prepared for the examination by solution treatment at 805 K for 3.3 hours after casting. By comparing the experiment and the theoretical dimensional changes of the specimens, it was verified that the theoretical model can be used for calculating the concentration of solid solution silicon in the α-Al of castings. The average concentrations of the solid solution silicon in the α-Al phases of as-cast Al–1%Si and Al–10%Si alloy specimens were also estimated as 0.81% and 0.73% respectively from the dimensional changes of the castings due to the heat-treatment at 743 K, 713 K and 473 K by the theoretical model.

 

This Paper was Originally Published in Japanese in J. JFS 90 (2018) 130–137.