High strength 7xxx aluminum alloys and methods of making the same

Abstract

Described herein are novel 7xxx series aluminum alloys. The alloys exhibit high strength. The alloys can be used in a variety of applications, including automotive, transportation, electronics, aerospace, and industrial applications. Also described herein are methods of making and processing the alloys. Further described herein are methods of producing a metal sheet, which include casting an aluminum alloy as described herein to form an ingot, homogenizing the ingot, hot rolling the ingot to produce a hot band, and cold rolling the hot band to a metal sheet of final gauge.

What is claimed is: 
     
         1 . An aluminum alloy sheet comprising 7.0-9.3 wt. % Zn, 0.20-2.60 wt. % Cu, 1.4-2.8 wt. % Mg, 0.10-0.35 wt. % Fe, 0.05-0.20 wt. % Si, 0.05-0.20 wt. % Zr, 0.01-0.10 wt. % Mn, 0.01-0.10 wt. % Cr, 0.001-0.035 wt. % Ti, up to 0.15 wt. % of impurities, and A1,
 wherein the aluminum alloy sheet has a yield strength greater than 500 MPa in a T6 temper;   wherein the aluminum alloy sheet comprises Al 3 Zr dispersoids having a diameter of 5 nm to 50 nm;   wherein the aluminum alloy sheet has a maximum corrosion test resultant pit depth of less than 40 microns after being immersed in a solution containing 57 g/L NaCl.   
     
     
         2 . The aluminum alloy sheet of  claim 1 , comprising 7.5-9.3 wt. % Zn, 0.3-2.4 wt. % Cu, 1.4-2.8 wt. % Mg, 0.1-0.30 wt. % Fe, 0.05-0.2 wt. % Si, 0.05-0.15 wt. % Zr, 0.01-0.05 wt. % Mn, 0.01-0.05 wt. % Cr, 0.001-0.05 wt. % Ti, and up to 0.15 wt. % of impurities, and A1. 
     
     
         3 . The aluminum alloy sheet of  claim 1 , comprising 8.0-9.2 wt. % Zn, 0.3-2.0 wt. % Cu, 1.6-2.6 wt. % Mg, 0.1-0.25 wt. % Fe, 0.07-0.15 wt. % Si, 0.09-0.15 wt. % Zr, 0.02-0.05 wt. % Mn, 0.03-0.05 wt. % Cr, 0.003-0.035 wt. % Ti, and up to 0.15 wt. % of impurities, and A1. 
     
     
         4 . The aluminum alloy sheet of  claim 1 , comprising 8.9-9.2 wt. % Zn, 0.3-1.6 wt. % Cu, 2.2-2.4 wt. % Mg, 0.18-0.23 wt. % Fe, 0.09-0.12 wt. % Si, 0.05-0.15 wt. % Zr, 0.04-0.09 wt. % Mn, 0.03-0.09 wt. % Cr, 0.01-0.02 wt. % Ti, and up to 0.15 wt. % of impurities, and A1. 
     
     
         5 . The aluminum alloy sheet of  claim 1 , further comprising up to 0.20% of one or more of Mo, Nb, Be, B, Co, Sn, Sr, V, In, Hf, Ag, Sc and Ni. 
     
     
         6 . The aluminum alloy sheet of  claim 1 , further comprising up to 0.10% of a rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. 
     
     
         7 . An automotive body part comprising the aluminum alloy sheet of  claim 1 . 
     
     
         8 . An electronic device housing comprising the aluminum alloy sheet of  claim 1 . 
     
     
         9 . An aerospace body part comprising the aluminum alloy sheet of  claim 1 . 
     
     
         10 . A product comprising the aluminum alloy sheet of  claim 1 , wherein the product is an extrusion, a casting, or a forging. 
     
     
         11 . A method of producing a metal product, comprising:
 casting an aluminum alloy to form an ingot or a slab, wherein the aluminum alloy comprises 7.0-9.3 wt. % Zn, 0.20-2.60 wt. % Cu, 1.46-2.8 wt. % Mg, 0.10-0.35 wt. % Fe, 0.05-0.20 wt. % Si, 0.05-0.20 wt. % Zr, 0.01-0.10 wt. % Mn, 0.01-0.10 wt. % Cr, 0.001-0.035 wt. % Ti, up to 0.15 wt. % of impurities, and A1;   homogenizing the ingot or the slab;   hot rolling the ingot or the slab to produce a hot band; and   cold rolling the hot band to a metal product with a final gauge.   
     
     
         12 . The method of  claim 11 , wherein the metal product is a sheet. 
     
     
         13 . The method of  claim 12 , further comprising subjecting the sheet to a solution heat treatment at a temperature of from 430° C. to 600° C. 
     
     
         14 . The method of  claim 13 , further comprising cooling the sheet to a temperature of from 25° C. to 120° C. at a cooling rate from 200° C. per second to 600° C. per second or from 2000° C. per second to 3000° C. per second. 
     
     
         15 . The method of  claim 14 , further comprising subjecting the sheet to an aging process. 
     
     
         16 . The method of  claim 15 , wherein the aging process comprises:
 heating the sheet to a temperature of from 100° C. to 140° C.;   maintaining the sheet at a temperature of from 100° C. to 140° C. for a period of time; and   cooling the sheet to room temperature.   
     
     
         17 . The method of  claim 15 , wherein the aging process comprises:
 heating the sheet to a temperature of from 100° C. to 140° C.;   maintaining the sheet at a temperature of from 100° C. to 140° C. for a first period of time;   heating the sheet to a temperature greater than 140° C.;   maintaining the sheet at a temperature greater than 140° C. for a second period of time; and   cooling the sheet to room temperature.   
     
     
         18 . The method of  claim 15 , further comprising subjecting the sheet to paint bake heat treatment. 
     
     
         19 . An aluminum sheet made according to the method of  claim 12 , wherein the sheet is in a T6 temper or a T7 temper. 
     
     
         20 . The sheet of  claim 19 , wherein the sheet has a yield strength of greater than 500 MPa and wherein the sheet comprises Al 3 Zr dispersoids having a diameter of 5 nm to 50 nm.