High strength Al-Zn alloy and method for producing such an alloy product

Abstract

The present invention relates to a high strength Al—Zn alloy product with an improved combination of corrosion resistance and toughness, the alloy including essentially (in weight percent): Zn: 6.0-9.5, Cu: 1.3-2.4, Mg: 1.5-2.6, Mn and Zr<0.25 but preferably in a range between 0.05 and 0.15 for higher Zn contents, other elements each less than 0.05 and less than 0.25 in total, balance aluminium, wherein (in weight percent): 0.1[Cu]+1.3<[Mg]<0.2[Cu]+2.15. The invention also relates to a method to produce these alloy products, and to some preferred applications thereof such as upper wing applications in aerospace.

Description

FIELD OF THE INVENTION The present invention relates to a wrought high strength Al—Zn alloy product with an improved combination of corrosion resistance and toughness, a method for producing a wrought high strength Al—Zn alloy product with an improved combination of corrosion resistance and toughness and a plate product of such alloy, optionally produced in accordance with the method. More specifically, the present invention relates to a wrought high strength Al—Zn alloy designated by the 7000-series of the international nomenclature of the Aluminium Association for structural aeronautical applications. Even more specifically, the present invention relates to a new chemistry window for an Al—Zn alloy product having improved combinations of strength, toughness and corrosion resistance, which does not need specific ageing or temper treatments. BACKGROUND OF THE INVENTION It is known in the art to use heat treatable aluminium alloys in a number of applications involving relatively hi...