Thick wrought 7xxx aluminum alloys, and methods for making the same

Abstract

Disclosed are improved thick wrought 7xxx aluminum alloy products, and methods for producing the same. The new 7xxx aluminum alloy products may realize an improved combination of environmentally assisted crack resistance and at least one of strength, elongation, and fracture toughness, among other properties. The new 7xxx aluminum alloy products generally include high amounts of manganese. The new 7xxx aluminum alloy products thus generally include from 0.15 to 0.50 wt. % Mn in combination with 5.5-7.5 wt. % Zn, 0.95-2.20 wt. % Mg, and 1.50-2.40 wt. % Cu.

What is claimed is: 
     
         1 . A wrought 7xxx aluminum alloy product comprising:
 0.15 to 0.50 wt. % Mn;   5.5-7.3 wt. % Zn;   0.95-2.2 wt. % Mg;   1.5-2.4 wt. % Cu;   up to 1.0 wt. % of grain structure control materials, wherein the grain structure control materials comprise at least one of Zr, Cr, Sc, and Hf; and   up to 0.15 wt. % Ti;   the balance being aluminum and unavoidable impurities;   wherein the wrought 7xxx aluminum alloy product has a thickness of from 1.5 to 12 inches.   
     
     
         2 . The wrought 7xxx aluminum alloy product  claim 1 , wherein the wrought 7xxx aluminum alloy product includes from 0.25 to 0.40 wt. % Mn. 
     
     
         3 . The wrought 7xxx aluminum alloy product of  claim 2 , wherein the wrought 7xxx aluminum alloy product includes from 6.25 to 7.0 wt. % Zn. 
     
     
         4 . The wrought 7xxx aluminum alloy product of  claim 3 , wherein the wrought 7xxx aluminum alloy product includes from 1.70 to 2.0 wt. % Cu. 
     
     
         5 . The wrought 7xxx aluminum alloy product of  claim 4 , wherein the wrought 7xxx aluminum alloy product includes from 1.40 to 1.90 wt. % Mg. 
     
     
         6 . The wrought 7xxx aluminum alloy product of  claim 1 , wherein the wrought 7xxx aluminum alloy product includes a total amount of copper and magnesium such that (wt. % Cu+wt. % Mg)≥is from 3.5 to 4.5 wt. %. 
     
     
         8 . The wrought 7xxx aluminum alloy product of  claim 1 , wherein the amounts of zinc, magnesium and copper within the 7xxx aluminum alloy product (in wt. %) satisfy the relationship 2.362≤Mg+0.429*Cu+0.067*Zn≤3.062. 
     
     
         9 . The wrought 7xxx aluminum alloy product of  claim 1 , wherein the amounts of zinc and magnesium are such that a weight ratio of zinc-to-magnesium is from 3.00:1 to 5.25:1. 
     
     
         10 . A wrought 7xxx aluminum alloy product comprising:
 0.25 to 0.40 wt. % Mn;   6.0-7.0 wt. % Zn;   1.35-2.05 wt. % Mg;   1.5-2.2 wt. % Cu;   wherein (wt. % Cu+wt. % Mg)≥3.2 wt. %;   wherein the amounts of zinc, magnesium and copper within the 7xxx aluminum alloy product (in wt. %) satisfy the relationship 2.362≤Mg+0.429*Cu+0.067*Zn≤3.062;   wherein the amounts of zinc and magnesium are such that a weight ratio of zinc-to-magnesium is not greater than 5.25:1;   up to 1.0 wt. % of grain structure control materials, wherein the grain structure control materials comprise at least one of Zr, Cr, Sc, and Hf; and   up to 0.15 wt. % Ti;   the balance being aluminum and unavoidable impurities;   wherein the wrought 7xxx aluminum alloy product has a thickness of from 1.5 to 12 inches.   
     
     
         11 . The wrought 7xxx aluminum alloy product of  claim 10 , comprising 0.25-0.35 wt. % Mn. 
     
     
         12 . The wrought 7xxx alloy product of  claim 11 , wherein the amounts of zinc, magnesium and copper within the 7xxx aluminum alloy product (in wt. %) satisfy the relationship 2.662≤Mg+0.429*Cu+0.067*Zn≤2.912. 
     
     
         13 . The wrought 7xxx aluminum alloy product of  claim 12 , wherein the 7xxx aluminum alloy product realizes a typical tensile yield strength (L) of at least 63 ksi. 
     
     
         14 . The wrought 7xxx aluminum alloy product of  claim 13 , wherein the 7xxx aluminum alloy product realizes a typical tensile yield strength (ST) of at least 57 ksi. 
     
     
         15 . The wrought 7xxx aluminum alloy product of  claim 14 , wherein the 7xxx aluminum alloy product realizes a typical K IC  plane-strain fracture toughness (L-T) of at least 25 ksi-sqrt-inch. 
     
     
         16 . The wrought 7xxx aluminum alloy product of  claim 15 , wherein the 7xxx aluminum alloy product realizes a typical K IC  plane-strain fracture toughness (S-L) of at least 20 ksi-sqrt-inch. 
     
     
         17 . The wrought 7xxx aluminum alloy product of  claim 16 , wherein the 7xxx aluminum alloy product realizes a typical elongation (L) of at least 8%. 
     
     
         18 . The wrought 7xxx aluminum alloy product of  claim 17 , wherein the 7xxx aluminum alloy product realizes a typical elongation (ST) of at least 3%. 
     
     
         19 . The wrought 7xxx aluminum alloy product of  claim 18 , wherein the 7xxx aluminum alloy product realizes a typical L-S crack deviation resistance (K max-dev ) of at least 25 ksi-sqrt-in. 
     
     
         20 . The wrought 7xxx aluminum alloy product of  claim 19 , wherein the 7xxx aluminum alloy product realizes a typical EAC resistance at 85% of TYS-ST of at least 80 days.