US 12,091,735 B2
Method of manufacturing an Al—Mg—Mn alloy plate product having an improved corrosion resistance
Nele Mareike Knaack, Koblenz (DE); Bernd Jacoby, Koblenz (DE); Achim Bürger, Koblenz (DE); and Otmar Martin Müller, Koblenz (DE)
Assigned to NOVELIS KOBLENZ GMBH, Koblenz (DE)
Appl. No. 16/973,920
Filed by ALERIS ROLLED PRODUCTS GERMANY GMBH, Koblenz (DE)
PCT Filed Jun. 3, 2019, PCT No. PCT/EP2019/064313
§ 371(c)(1), (2) Date Dec. 10, 2020,
PCT Pub. No. WO2019/238449, PCT Pub. Date Dec. 19, 2019.
Claims priority of application No. 18176931 (EP), filed on Jun. 11, 2018.
Prior Publication US 2021/0269906 A1, Sep. 2, 2021
Int. Cl. C22F 1/047 (2006.01); C22C 21/08 (2006.01)
CPC C22F 1/047 (2013.01) [C22C 21/08 (2013.01); C22C 2202/00 (2013.01)] 17 Claims
 
1. A method of manufacturing an Al—Mg—Mn aluminium alloy plate product having a final gauge in a range of 3 mm or more, the method comprising the steps of:
(a) providing a rolling feedstock material of an aluminium alloy having a composition comprising of, in wt. %,
Mg 3.5% to 5.3%
Mn 0.20% to 1.2%
Fe up to 0.4%
Si up to 0.4%
Cu up to 0.10%
Cr up to 0.25%
Zr up to 0.25%
Zn up to 0.2%
Ti up to 0.15%,
unavoidable impurities and the balance aluminium;
(b) preheating and/or homogenisation;
(c) hot rolling of the rolling feedstock to a rolled final gauge in a range of 3 mm to 310 mm;
(d) a first cold working operation selected from the group consisting of (i) stretching in a range of 3% to 20%, and (ii) cold rolling with a cold rolling reduction in a range of 5% to 25%, to produce a cold worked plate;
(e) annealing of the cold worked plate at an annealing temperature in a range of 200° C. to 280° C.;
(f) cooling the annealed plate from the annealing temperature to a temperature of about 200° C. at a rate of not more than 10° C. per hour, cooling from the temperature of about 200° C. to a temperature below about 85° C. at a higher cooling rate, and then further cooling the annealed plate to ambient temperature; and
(g) a second cold working operation selected from the group consisting of (i) stretching in a range of 0.4% to 3%, and (ii) cold rolling with a cold rolling reduction in a range of 0.5% to 5%,
wherein the Al—Mg—Mn aluminium alloy plate product has a mass loss less than 25 mg/cm2, as tested per ASTM G67-13.