High-strength corrosion-resistant 6xxx series aluminum alloys and methods for preparing the same

Abstract

Described herein are 6xxx series aluminum alloys which exhibit high corrosion resistance while maintaining high strength-to-weight ratio, formability, and weldability. The 6xxx series aluminum alloys include Cr to improve intergranular corrosion resistance while maintaining high strength and formability. 6xxx series aluminum alloys including Cr in amount from 0.05 wt. % to 0.50 wt. % improved IGC resistance. The Cr addition in 6xxx series aluminum alloys improves the corrosion resistance of aluminum alloy products formed from the aluminum alloy without causing a substantial loss in strength.

What is claimed is: 
     
         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.