AlMgMn alloy product with improved corrosion resistance

Patent metadata

Field	Value
Publication number	US-12024765-B2
Application number	US-201917275669-A
Country	US
Kind code	B2
Filing date	Sep 9, 2019
Priority date	Sep 13, 2018
Publication date	Jul 2, 2024
Grant date	Jul 2, 2024

Abstract

The invention relates to a method for manufacturing an aluminum alloy sheet, wherein an aluminum alloy is prepared with the following composition, in wt %: Mg: 4.0-5.2, Mn: 0.40-1.0, Zn: 0.15-0.40, at least one element selected from Ti, Cr, Cu and Zr, the content of the element, if selected, being 0.01-0.15 for Ti, 0.05-0.25 for Cr, 0.02-0.25 for Cu, 0.05-0.25 for Zr, Fe: <0.40, Si: <0.40, other elements or impurities <0.05 each and <0.15 in total, the remainder being aluminum. A rolling plate is cast by vertical semi-continuous casting, and said optionally homogenised plate is hot-rolled in two successive stages to obtain a sheet. The sheets obtained by the method according to the invention are advantageous, in particular for shipbuilding, since they demonstrate, after being exposed for 7 days to a temperature of 100° C., a weight loss of less than 15 mg/cm2 during a corrosion test according to the ASTM G67 standard.

First claim

The invention claimed is:

1. A method for manufacturing an aluminum alloy sheet, comprising a) preparing an aluminum alloy, with the composition, as % by weight
Mg: 4.0-5.2,
Mn: 0.40-1.0,
Zn: 0.15-0.40,
at least one element selected from Ti, Cr, Cu and Zr, with a content, if it is selected, of 0.01-0.15 for Ti, 0.05-0.25 for Cr, 0.02-0.25 for Cu, 0.05-0.25 for Zr,
Fe: <0.40,
Si: <0.40,
other elements or impurities <0.05 each and <0.15 in total, the remainder aluminum,
b) casting a slab by vertical semicontinuous casting,
c) optionally, homogenizing said slab,
d) hot rolling said optionally homogenized slab, in two successions, in order to obtain a sheet
dl) hot-rolling on a reversible mill to a thickness of between 12 and 35 mm,
d 2 ) hot-rolling on a tandem mill to a thickness of between 3 and 12 mm, wherein the final temperature is at least 240° C. and is less than 300° C.,

e) optionally, cold rolling said sheet, to a thickness of between 1 and 7 mm,
f) optionally, carrying out a final heat treatment of said optionally cold-rolled sheet at a temperature below 300° C.

2. Method according to claim 1 , wherein the Zn content is between 0.15 and 0.35% by weight and optionally between 0.18 and 0.30% by weight.

3. Method according to claim 1 , wherein the homogenization c is not performed but a simple reheating is carried out before hot rolling at a temperature of between 490° and 535° C.

4. Method according to claim 1 , wherein the final heat treatment f is not performed and wherein the sheet is used in the as-manufactured temper.

5. Method according to claim 1 , wherein the final temperature during d2 is between 240° C. and 280° C.

6. Method according to claim 1 , wherein a reduction in thickness of at least 30% is performed at a temperature of between 240° C. and 380° C. during d2.

7. An aluminum alloy sheet with a thickness of between 1 and 12 mm with a composition, as % by weight,
Mg: 4.0-5.2,
Mn: 0.40-1.0,
Zn: 0.15-0.40,
at least one element selected from Ti, Cr, Cu and Zr, with a content, if it is selected, of 0.01-0.15 for Ti, 0.05-0.25 for Cr, 0.02-0.25 for Cu, 0.05-0.25 for Zr,
Fe: <0.40,
Si: <0.40,
other elements or impurities <0.05 each and <0.15 in total, the remainder aluminum,
able to be obtained by the method according to claim 1 having, after exposure of 7 days at 100° C., a weight loss of less than 15 mg/cm 2 during a corrosion test in accordance with ASTM G67.
Mn: 0.40-1.0,
Zn: 0.15-0.40,
at least one element selected from Ti, Cr, Cu and Zr, with a content, if it is selected, of 0.01-0.15 for Ti, 0.05-0.25 for Cr, 0.02-0.25 for Cu, 0.05-0.25 for Zr,
Fe: <0.40,
Si: <0.40,
other elements or impurities <0.05 each and <0.15 in total, the remainder aluminum,
b) casting a slab by vertical semicontinuous casting,
c) optionally, homogenizing said slab,
d) hot rolling said optionally homogenized slab, in two successions, in order to obtain a sheet
d1) hot-rolling on a reversible mill to a thickness of between 12 and 35 mm,
d2) hot-rolling on a tandem mill to a thickness of between 3 and 12 mm, wherein the final temperature is at least 240° C. and is less than 300° C.,

e) optionally, cold rolling said sheet, to a thickness of between 1 and 7 mm,
f) optionally, carrying out a final heat treatment of said optionally cold-rolled sheet at a temperature below 300° C.

8. Sheet according to claim 7 , wherein the Mg content is between 4.0 and 4.6% by weight.

9. Aluminum alloy sheet according to claim 8 , wherein the degree of KAM mean misorientation is at least 0.75.

10. A product comprising a sheet according to claim 7 for use in naval construction or for constructing an industrial vehicle.

11. The aluminum alloy sheet according to claim 7 , wherein the Mn content is between 0.45 and 0.9% by weight.

12. The aluminum alloy sheet according to claim 7 , wherein the Zn content is between 0.15 and 0.35% by weight.

13. The aluminum alloy sheet according to claim 7 , wherein the Cu content is between 0.05 and 0.15% by weight.

14. The aluminum alloy sheet according to claim 7 , wherein the Cr content is less than 0.1% by weight.

15. The aluminum alloy sheet according to claim 7 , wherein the Fe content is less than 0.35% by weight.

16. The aluminum alloy sheet according to claim 7 , wherein the Si content is between 0.05 and 0.15% by weight.

17. The aluminum alloy sheet according to claim 7 , wherein the Mg content is between 4 . 0 and 4 . 6 % by weight, and the Mn content is between 0.45 and 0.6% by weight.

18. The aluminum alloy sheet according to claim 7 , wherein the Mg content is between 4.7 and 5.2% by weight, and the Mn content is between 0.7 and 0.9% by weight.

19. The aluminum alloy sheet according to claim 7 , wherein the aluminum alloy sheet is cold rolled to a thickness of between 1 and 7 mm.

20. The aluminum alloy sheet according to claim 19 , wherein the aluminum alloy sheet has a thickness of between 2 and 4 mm.

Assignees

• Constellium Issoire
• Constellium Rolled Products Ravenswood Llc

Inventors

• Ledoux Marine
• DAVO GUTIERREZ Maria Belen
• Warner Timothy

Classifications

• C22C21/08

  with silicon · CPC title

• C22F1/047 Primary

  of alloys with magnesium as the next major constituent · CPC title

• C22C21/06

  with magnesium as the next major constituent · CPC title

• C22F1/04 Primary

  of aluminium or alloys based thereon · CPC title