Factors influencing tensile mechanical properties of Al-7Si-Mg casting alloys A356/7

Abstract

Factors that influence the tensile mechanical properties of Al-7Si-Mg alloys A356/7 are critically analyzed. Different casting methods (SSM-HPDC, gravity die casting and investment casting), chemical composition variations and different temper conditions are considered. It is shown that the casting method employed has an influence on the primary α-Al structure, but does not influence the age-hardening response. The most important elements that influence mechanical properties are magnesium and iron. An equation to convert Vickers hardness to 0.2% proof stress in different temper conditions using the strain hardening exponent is proposed. Linear correlations between hardness, strength and (at% Mg-content available for precipitation hardening)1/2 are found. It is shown that ASTM Standard B969-10 needs to be revised.