HIGH-STRENGTH CORROSION-RESISTANT 6XXX SERIES ALUMINUM ALLOYS AND METHODS FOR PREPARING THE SAME
Described herein are 6 xxx series aluminum alloys which exhibit high corrosion resistance while maintaining high strength-to-weight ratio, formability, and weldability. The 6 xxx series aluminum alloys include Cr to improve intergranular corrosion resistance while maintaining high strength and formability. 6 xxx series aluminum alloys including Cr in amount from 0.05 wt. % to 0.50 wt. % improved IGC resistance. The Cr addition in 6 xxx series aluminum alloys improves the corrosion resistance of aluminum alloy products formed from the aluminum alloy without causing a substantial loss in strength.
1 . An aluminum alloy comprising 0.50-2.50 wt. % Si, 0.10-0.50 wt. % Fe, 0.01-1.20 wt. % Cu, 0.01-0.50 wt. % Mn, 0.30-1.50 wt. % Mg, 0.05-0.50 wt. % Cr, 0.01-0.50 wt. % Zn, up to 0.20 wt. % Zr, up to 0.15 wt. % of impurities, and Al.
2 . The aluminum alloy of claim 1 , wherein the aluminum alloy comprises 0.60-2.25 wt. % Si, 0.15-0.50 wt. % Fe, 0.01-1.00 wt. % Cu, 0.04-0.45 wt. % Mn, 0.35-1.30 wt. % Mg, 0.10-0.50 wt. % Cr, 0.01-0.40 wt. % Zn, up to 0.20 wt. % Zr, up to 0.15 wt. % of impurities, and Al.
3 . The aluminum alloy of claim 1 , wherein the aluminum alloy comprises 0.70-2.0 wt. % Si, 0.20-0.50 wt. % Fe, 0.05-1.00 wt. % Cu, 0.04-0.40 wt. % Mn, 0.40-1.20 wt. % Mg, 0.10-0.45 wt. % Cr, 0.01-0.30 wt. % Zn, up to 0.15 wt. % Zr, up to 0.15 wt. % of impurities, and Al.
4 . The aluminum alloy of claim 1 , wherein the aluminum alloy comprises 0.80-1.9 wt. % Si, 0.23-0.50 wt. % Fe, 0.20-1.00 wt. % Cu, 0.15-0.40 wt. % Mn, 0.45-1.00 wt. % Mg, 0.15-0.45 wt. % Cr, 0.01-0.20 wt. % Zn, 0.01-0.10 wt. % Zr, up to 0.15 wt. % of impurities, and Al.
5 . The aluminum alloy of claim 1 , wherein the aluminum alloy comprises 1.00-1.70 wt. % Si, 0.30-0.45 wt. % Fe, 0.30-0.80 wt. % Cu, 0.20-0.40 wt. % Mn, 0.50-0.90 wt. % Mg, 0.20-0.40 wt. % Cr, 0.01-0.15 wt. % Zn, 0.05-0.10 wt. % Zr, up to 0.15 wt. % of impurities, and Al.
6 . The aluminum alloy of claim 1 , wherein a ratio of Cr:Cu is at least 0.25:1.
7 . The aluminum alloy of claim 1 , wherein the aluminum alloy comprises 0.20-0.50 wt. % Cu, 0.05 to 0.30 wt. % Cr, and a ratio of Cr:Cu is at least 0.3:1.
8 . The aluminum alloy of claim 1 , wherein the aluminum alloy comprises greater than 0.50 wt. % Cu, 0.20 to 0.50 wt. % Cr, and a ratio of Cr:Cu is at least 0.5:1.
9 . The aluminum alloy of claim 1 , wherein the yield strength of the aluminum alloy is at least 300 MPa when in a T6 temper.
10 . The aluminum alloy of claim 1 , wherein an ultimate tensile strength of the aluminum alloy is at least 350 MPa when in a T6 temper.
11 . The aluminum alloy of claim 1 , wherein the aluminum alloy comprises a inner bend angle less than 140°, when in a T6 temper, as measured according to VDA238-100 (2022).
12 . The aluminum alloy of claim 1 , wherein the aluminum alloy is pre-strained.
13 . The aluminum alloy of claim 12 , wherein the aluminum alloy is subjected to pre-strain treatment and has a maximum corrosion depth less than 300 μm when subjected to an intergranular corrosion (IGC) test set forth in ISO 11846B (2022) for 24 hours.
14 . The aluminum alloy of claim 1 , wherein the aluminum alloy is in a T4 temper.
15 . The aluminum alloy of claim 14 , wherein the aluminum alloy has a maximum corrosion depth less than 400 μm when subjected to an intergranular corrosion (IGC) test set forth in ISO 11846B (2022) for 24 hours.
16 . A method of producing an aluminum alloy comprising:
casting an aluminum alloy to form a cast product, wherein the aluminum alloy comprises 0.50-2.50 wt. % Si, 0.10-0.50 wt. % Fe, 0.01-1.20 wt. % Cu, 0.01-0.50 wt. % Mn, 0.30-1.50 wt. % Mg, 0.05-0.50 wt. % Cr, 0.01-0.50 wt. % Zn, up to 0.20 wt. % Zr, up to 0.15 wt. % of impurities, and Al;
homogenizing the cast product;
hot rolling the cast product to produce a hot rolled product;
cold rolling the rolled product to produce a final gauge rolled product; and
solution heat treating the final gauge rolled product.
17 . The method of claim 16 , further comprising aging the final gauge rolled product to a T temper.
18 . The method of claim 17 , wherein the T temper is a T4 temper, a T6 temper, or a T8x temper.
19 . The method of claim 16 , further comprising pre-straining the final gauge rolled product.
20 . The method of claim 16 , further comprising naturally aging the final gauge rolled product to a T4 temper and artificially aging the final gauge rolled product at a temperature from 150° C. to 200° C. from 10 min to 1 hour, wherein the final gauge rolled product has a maximum corrosion depth less than 300 μm when subjected to an intergranular corrosion (IGC) test set forth in ISO 11846B (2022) for 24 hours.