High-strength and easily formable AlMg-strip, and method for producing the same

Patent metadata

Field	Value
Publication number	US-11352686-B2
Application number	US-201715849387-A
Country	US
Kind code	B2
Filing date	Dec 20, 2017
Priority date	Jun 25, 2015
Publication date	Jun 7, 2022
Grant date	Jun 7, 2022

Abstract

Provided is a method for producing an aluminium alloy strip from a non-precipitation-hardenable aluminium alloy having the following alloying constituents in wt %: 3.6%≤Mg≤6%, Si≤0.4%, Fe≤0.5%, Cu≤0.15%, 0.1%≤Mn≤0.4%, Cr≤0.05%, Zn≤0.20%, Ti≤0.20%, with the remainder Al and unavoidable impurities, individually at most 0.05 wt %, in total at most 0.15 wt %. In the method, a rolling ingot is cast. The rolling ingot is homogenised and then hot rolled into a hot strip. Then, the strip is cold rolled before a last intermediate annealing. The intermediate annealing is carried out to produce a recrystallised microstructure. The intermediate-annealed aluminium alloy strip is cold rolled to a final thickness, and the aluminium alloy strip is reverse annealed in the coil to a final thickness.

First claim

The invention claimed is:

1. A method for producing an aluminium strip or sheet from an aluminium alloy having the following alloying constituents in wt %:
3.6%≤Mg≤6%,
Si≤0.4%,
Fe≤0.5%,
Cu≤0.15%,
0.1%≤Mn≤0.4%,
Cr≤0.05%,
Zn≤0.20%,
Ti≤0.20%,
with the remainder Al and unavoidable impurities, individually at most 0.05 wt %, in total at most 0.15 wt %,
wherein the method comprises the following steps:
casting a rolling ingot consisting of the specified aluminium alloy,
homogenising the rolling ingot at 480° C. to 550° C. for at least 0.5 h,
hot rolling the rolling ingot at a temperature of 280° C. to 500° C. into a hot strip,
cold rolling the aluminium alloy strip after hot rolling with a degree of rolling of 20% to 30% before a last intermediate annealing,
carrying out at least a last intermediate annealing on the cold-rolled aluminium alloy strip at 300° C. to 500° C. in such a way that the cold-rolled aluminium alloy strip has a recrystallised microstructure after the intermediate annealing,
cold rolling the intermediate-annealed aluminium alloy strip with a degree of rolling of 40% to 60% to a final thickness and
reverse annealing the aluminium alloy strip in a coil at the final thickness, wherein the metal temperature is 220-240° C. for at least 0.5 h.

2. The method according to claim 1 , wherein the aluminium alloy strip is cold rolled to a final thickness of 0.5 mm to 5.0 mm.

3. The method according to claim 1 , wherein the aluminium alloy strip is cold rolled to a final thickness of 1.0 mm to 3.0 mm.

4. A cold-rolled and reverse annealed aluminium alloy strip or sheet, produced using a method according to claim 1 , consisting of an aluminium alloy having the following alloying constituents:
3.6%≤Mg≤6%,
Si≤0.4%,
Fe≤0.5%,
Cu≤0.15%,
0.1%≤Mn≤0.4%,
Cr≤0.05%,
Zn≤0.20%,
Ti≤0.20%,
with the remainder Al and unavoidable impurities, individually at most 0.05 wt %, in total at most 0.15 wt %,
wherein the aluminium alloy strip has
a yield strength R p0.2 of more than 190 MPa,
a uniform elongation A g of at least 14%,
a percentage reduction of area after fracture Z of more than 50% and
in the corrosion test according to ASTM G67, after a prior sensitization heat treatment for 17 h at 130° C., a mass loss of less than 15 mg/cm 2 .

5. The aluminium alloy strip or sheet according to claim 4 , wherein the Mg content of the aluminium alloy strip is 4.2 wt % to 6 wt %.

6. The aluminium alloy strip or sheet according to claim 4 , wherein the Mn content of the aluminium alloy strip is 0.1 wt % to 0.3 wt %.

7. The aluminium alloy strip or sheet according to claim 4 , wherein the Cr content of the aluminium alloy strip is less than 0.01 wt %.

8. The aluminium alloy strip or sheet according to claim 4 , wherein the aluminium alloy strip has one or more of the following restrictions on the proportions of the alloying constituents in wt %:
Si≤0.2%,
Fe≤0.35% or
Zn≤0.01%.

9. The aluminium alloy strip or sheet according to claim 4 , wherein the aluminium alloy strip has one or more of the following properties:
a yield strength R p0.2 of more than 200 MPa,
a uniform elongation A g of at least 15%,
a percentage reduction of area after fracture Z of at least 55% or
in the corrosion test according to ASTM G67, after a prior sensitization heat treatment for 17 h at 130° C., a mass loss of less than 10 mg/cm 2 .

10. The aluminium alloy strip or sheet according to claim 4 , wherein the aluminium alloy strip has a thickness of 0.5 mm to 5.0 mm.

11. An aluminium alloy strip or sheet according to claim 4 for producing structural parts or chassis components of a motor vehicle.

12. The aluminium alloy strip or sheet according to claim 4 , wherein the Mg content of the aluminium alloy strip is 4.2 wt % to 5.2 wt %.

13. The aluminium alloy strip or sheet according to claim 4 , wherein the aluminium alloy strip has a thickness of 1.0 mm to 3.0 mm.

14. A method for producing an aluminium strip or sheet from an aluminium alloy having the following alloying constituents in wt %:
3.6%≤Mg≤6%,
Si≤0.4%,
Fe≤0.5%,
Cu≤0.15%,
0.1%≤Mn≤0.4%,
Cr≤0.05%,
Zn≤0.20%,
Ti≤0.20%,
with the remainder Al and unavoidable impurities, individually at most 0.05 wt %, in total at most 0.15 wt %,
wherein the method comprises the following steps:
casting a rolling ingot consisting of the specified aluminium alloy,
homogenising the rolling ingot at 480° C. to 550° C. for at least 0.5 h,
hot rolling the rolling ingot at a temperature of 280° C. to 500° C. into a hot strip,
cold rolling the aluminium alloy strip after hot rolling with a degree of rolling of 20% to 26% before a last intermediate annealing,
carrying out at least a last intermediate annealing on the cold-rolled aluminium alloy strip at 300° C. to 500° C. in such a way that the cold-rolled aluminium alloy strip has a recrystallised microstructure after the intermediate annealing,
cold rolling the intermediate-annealed aluminium alloy strip with a degree of rolling of 50% to 60% to a final thickness and
reverse annealing the aluminium alloy strip in a coil at the final thickness, wherein the metal temperature is 220-240° C. for at least 0.5 h.

Assignees

• Engler Olaf
• Brinkman Henk Jan
• Hydro Aluminium Rolled Prod

Inventors

• Engler Olaf
• Brinkman Henk-Jan

Classifications

• C22F1/047 Primary

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

• C22C21/06 Primary

  with magnesium as the next major constituent · CPC title

• C22C21/08

  with silicon · CPC title