Al—Mg—Zn wrought alloy product and method of its manufacture

Method of manufacturing aluminum wrought product comprising the steps of:

• a. casting stock of an ingot of an Al—Mg alloy having a chemical composition comprising, in wt. %,
• Mg
• 3.0 to 7.0
• Zn
• 0.6 to 2.8
• Mn
• 0 to 1.0
• Cu
• 0 to 2.0
• Sc
• 0 to 0.5,
• at least one element selected from the group consisting of:
• Zr
• 0.04 to 0.4
• Cr
• 0.04 to 0.4
• Hf
• 0.04 to 0.4 and
• Ti
• 0.01 to 0.3,
• Fe
• max. 0.3
• Si
• max. 0.3,
• inevitable impurities, balance aluminium, and whereby the range for the Zn-content is a function of the Mg-content according to:
• lower-limit of the Zn-range:
• [Zn]=0.34[Mg]−0.4, and
• upper-limit of the Zn-range:
• [Zn]=0.34[Mg]+0.4, and
• wherein the aluminium alloy product is substantially Li free;
• b. preheating and/or homogenising the cast stock;
• c. hot working the stock by one or more methods selected from the group consisting of rolling, extrusion, and forging;
• d. annealing of the hot worked stock, wherein the annealing treatment is carried out at a temperature in a range of 350° C. to 475° C., followed by rapid cooling;
• e. cold working the annealed and cooled stock;
• f. stretching the cold worked stock in a range of 0.5 to 10%;
• h. heat treating of the stock to achieve a desired temper.