Structure, property, processing relations in cast, solutionized, and aged Al-Si-Cu-Mg and Al-Si-Mg alloys

An empirical approach is used to find design rules to relate tensile strength of cast and age hardened aluminum alloys to microstructural features (dendrite arm spacing and volume fraction porosity) and to process parameters (local solidification time, melt hydrogen concentration, and solution treatment time). End-chilled plate castings are used to provide a wide range of as-cast microstructures in Al-Si-Cu-Mg (based on 319) and Al-Si-Mg (based on 356) alloys. Coupons cut from the plates are given brief to extended solution treatments, quenched and given a uniform aging treatment. Tensile properties of the cast and heat treated coupons are measured and fit to an empirical relation. The empirical relation is validated by casting, heat treating, and testing additional sets of plate castings and the empirical relations are used to make microstructureproperty maps that can be used in computer assisted process design.