	US 11,981,986 B2
	7XXX-series aluminium alloy product
Achim Bürger, Rheinland-Pfalz (DE); Sunil Khosla, Nottingham (GB); Christian Gerhard Krechel, Koblenz (DE); Sabine Maria Spangel, Rheinland-Pfalz (DE); and Philippe Meyer, Koblenz (DE)
Assigned to NOVELIS KOBLENZ GMBH, Koblenz (DE)
Appl. No. 17/421,933
Filed by Aleris Rolled Products Germany GmbH, Koblenz (DE)
PCT Filed Jan. 9, 2020, PCT No. PCT/EP2020/050370 § 371(c)(1), (2) Date Jul. 9, 2021, PCT Pub. No. WO2020/148140, PCT Pub. Date Jul. 23, 2020.
Claims priority of application No. 19152546 (EP), filed on Jan. 18, 2019.
Prior Publication US 2022/0112588 A1, Apr. 14, 2022
Int. Cl. C22C 21/10 (2006.01); C22F 1/053 (2006.01)

CPC C22F 1/053 (2013.01) [C22C 21/10 (2013.01)]

21 Claims

1. A wrought 7xxx-series aluminium alloy product having a composition comprising, in wt. %,

Zn 6.50 to 7.20,

Mg 2.30 to 2.60,

Cu 1.30 to 1.80,

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 wherein said product is 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 K_max-devvalue 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, testing in a load controlled fatigue test and crack deviation defined as a crack deviating more than 20° from the intended fracture plane.