Patent ID: 8252128

Claim:
A method of producing a population of aluminum alloy billets comprising (a) performing more than one cast of metal wherein each cast of metal converts a body of molten metal comprising virgin metal and recycled scrap into a plurality of billets, while (b) controlling purity of virgin metal and quality and amount of recycled scrap in each cast such that all casts have a Cu level below 0.015 wt. %, and wherein said body has a composition within a specification such that every billet of the population has a composition (in wt %) consisting essentially of: Constituent Range Fe <0.35 Si 0.20-0.6 Mn <0.10 Mg 0.25-0.9 Cu <0.015 Ti <0.10 Cr <0.10 Zn <0.03 balance Al of commercial purity.