Patent ID: 11981986

Abstract:
The invention relates to a wrought 7xxx-series aluminium alloy product having a composition comprising, in wt. %, Zn 6.40 to 7.50, Mg 2.15 to 2.75, Cu 1.20 to 2.00, and wherein Cu+Mg<4.50, and wherein Mg<2.5+5/3(Cu−1.2), Fe up to 0.25, Si up to 0.25, and optionally one or more elements selected from the group consisting of: (Zr up to 0.3, Cr up to 0.3, Mn up to 0.45, Ti up to 0.25, Sc up to 0.5, Ag up to 0.5), the balance being aluminium and impurities, and having been aged to achieve a conventional tensile yield strength (in MPa) measured in the L-direction measured at quarter thickness of more than 485−0.12*(t−100) MPa (t being the thickness of the product in mm); a minimum life without failure due to stress corrosion cracking (SCC) measured in accordance with ASTM G47-98 of at least 30 days at a short transverse (ST) stress level of 170 MPa; and a minimum Kmax-dev value without crack deviation due to crack propagation testing in standard atmosphere at room temperature in accordance with ASTM E647-13e01 in L-S direction on CT samples of at least 40 MPa√m on average.