Aluminum sheet products having improved fatigue crack growth resistance and methods of making same

Abstract

Aluminum sheet products having highly anisotropic grain microstructures and highly textured crystallographic microstructures are disclosed. The products exhibit improved strength and improved resistance to fatigue crack growth, as well as other advantageous properties such as improved combinations of strength and fracture toughness. The sheet products are useful for aerospace and other applications, particularly aircraft fuselages.

1 - 100 . (canceled)  
   
   
       101 . a method of making an aluminum allov sheet product, the method: comprising: 
 providing an aluminum alloy;    hot rolling the aluminum alloy to form a sheet;    recovery annealing the hot rolled sheet;    solution heat treating the recovery annealed sheet; and    recovering a sheet product comprising an anisotropic microstructure defined by grains having an average length to width aspect ratio of greater than about 4 to 1.    
   
   
       102 . The method of  claim 101 , wherein the recovery anneal is performed at a temperature of from about 300 to about 1,000° F. for a time of from about 0.5 to about 96 hours.  
   
   
       103 . The method of  claim 101 , wherein the recovery anneal is performed at a temperature of from about 400 to about 700° F.  
   
   
       104 . The method of  claim 103 , wherein the sheet product is unrecrystallized.  
   
   
       105 . The method of  claim 101 , wherein the recovery anneal is performed at a temperature of from about 600 to about 1,000° F.  
   
   
       106 . The method of  claim 105 , wherein the sheet product is recrystallized.  
   
   
       107 . The method of  claim 101 , further comprising intermediate annealing the sheet prior to the recovery anneal.  
   
   
       108 . The method of  claim 107 , wherein the intermediate anneal is performed during the hot rolling.  
   
   
       109 . The method of  claim 107 , wherein the intermediate anneal is performed at a temperature of from about 400 to about 1,000° F.  
   
   
       110 . The method of  claim 101 , further comprising cold rolling the sheet after the hot rolling.  
   
   
       111 . The method of  claim 110 , further comprising intermediate annealing the, sheet prior to the recovery anneal.  
   
   
       112 . The method of  claim 111 , wherein the intermediate anneal is performed during the cold rolling.  
   
   
       113 . The method of  claim 112 , further comprising intermediate annealing during the hot rolling.  
   
   
       114 . The method of  claim 110 , wherein the intermediate anneal is performed at a temperature of from about 400 to about 1,000° F.  
   
   
       115 . The method of  claim 101 . wherein the hot rolling step includes multiple hot rolling operations.  
   
   
       116 . The method of  claim 115 , wherein the hot rolling operations include finish hot rolling prior to the recovery anneal.  
   
   
       117 . The method of  claim 116 , further comprising intermediate annealing the sheet during the finish hot rolling.  
   
   
       118 . The method of  claim 101 , further comprising cold working the solution heat treated sheet.  
   
   
       119 . The method of  claim 101 , wherein the aluminum alloy is an Al—Cu alloy comprising aluminum, from about 1 to about 5 weight percent Cu, up to about 6 weight percent Mg, up to about 1 weight percent Mn, and up to about 0.5 weight percent Zr.  
   
   
       120 . The method of  claim 101 , wherein the Al—Cu base alloy comprises at least about 3 weight percent Cu.  
   
   
       121 . The method of  claim 101 , wherein the Al—Cu base alloy includes from about 3.5 to about 4.5 weight percent Cu, from about 0.6 to about 1.6 weight percent Mg, from about 0.3 to about 0.7 weight percent Mn, and from about 0.08 to about 0.13 weight percent Zr.  
   
   
       122 . The method of  claim 101 , wherein the Al—Cu base alloy includes from about 3.8 to about 4.4 weight percent Cu, from about 0.3 to about 0.7 weight percent Mn, from about 1.0 to about 1.6 weight percent Mg, and from about 0.09 to about 0.12 weight percent Zr.  
   
   
       123 . The method of  claim 101 , wherein the Al—Cu base alloy includes from about 3.4 to about 4.0 weight percent Cu, from 0 to about 0.4 weight percent Mn, from about 1.0 to about 1.6 weight percent Mg, and from about 0.09 to about 0.12 weight percent Zr.  
   
   
       124 . The method of  claim 101 , wherein the Al—Cu base alloy includes from about 3.2 to about 3.8 weight percent Cu, from about 0.3 to about 0.7 weight percent Mn, from about 1.0 to about 1.6 weight percent Mg, from about 0.09 to about 0.12 weight percent Zr, and from about 0.25 to about 0.75 weight percent Li.  
   
   
       125 . The method of  claim 101 , wherein the aluminum alloy is an Al—Mg base alloy comprising aluminum, from about 0.2 to about 7 weight percent Mg, from 0 to about 1 weight percent Mn, from 0 to about 1.5 weight percent Cu, from 0 to about 3 weight percent Zn, and from 0 to about 0.5 weight percent Si.  
   
   
       126 . The method of  claim 101 , wherein the aluminum alloy is an Al—Mg—Si base alloy comprising aluminum, from about 0.1 to about 2.5 weight percent Mg, from about 0.1 to about 2.5 weight percent Si, from 0 to about 2 weight percent Cu, from 0 to about 3 weight percent Zn, and from 0 to about 1 weight percent Li.  
   
   
       127 . The method of  claim 101 , wherein the aluminum alloy is an Al—Zn base alloy comprising aluminum, from about 1 to about 10 weight percent Zn, from about 0.1 to about 3 weight percent Cu, from about 0.1 to about 3 weight percent Mg, from 0 to about 2 weight percent Li, and from 0 to about 2 weight percent Ag.  
   
   
       128 . The method of  claim 101 , wherein the sheet product has a thickness of up to about 0.35 inch.  
   
   
       129 . The method of  claim 101 , wherein the sheet product is unrecrystallized.  
   
   
       130 . The method of  claim 129 , wherein the unrecrystallized sheet product has a Brass texture of greater than 20.  
   
   
       131 . The method of  claim 129 , wherein the unrecrystallized sheet product has a Brass texture of greater than 30.  
   
   
       132 . The method of  claim 129 , wherein the unrecrystallized sheet product has a Brass texture of greater than 40.  
   
   
       133 . The method of  claim 101 , wherein the sheet product is recrystallized.  
   
   
       134 . The method of  claim 133 , wherein the recrystallized sheet product has a Goss texture of greater than 20.  
   
   
       135 . The method of  claim 133 , wherein the recrystallized sheet product has a Goss texture of greater than 30.  
   
   
       136 . The method of  claim 133 , wherein the recrystallized sheet product has a Goss texture of greater than 40.  
   
   
       137 . A method of making an aluminum alloy sheet product, the method comprising: 
 providing an aluminum alloy;    hot rolling the aluminum alloy to form a sheet;    intermediate annealing the hot rolled sheet;    solution heat treating the intermediate annealed sheet;    recovering a sheet product comprising an anisotropic microstructure defined by grains having an average length to width aspect ratio of greater than about 4 to 1.    
   
   
       138 . The method of  claim 137 , wherein the intermediate anneal is performed at a temperature of from about 400 to about 1,000° F.  
   
   
       139 . The method of  claim 137 , wherein the intermediate anneal is performed during the hot rolling.  
   
   
       140 . The method of  claim 137 , further comprising recovery annealing the sheet after the intermediate anneal and prior to the solution heat treatment.  
   
   
       141 . The method of  claim 137 , further comprising cold rolling the sheet after the hot rolling.  
   
   
       142 . The method of  claim 141 , wherein the intermediate anneal is performed during the cold rolling.  
   
   
       143 . The method of  claim 142 , further comprising recovery annealing the sheet after the cold rolling.  
   
   
       144 . The method of  claim 142 , further comprising performing another intermediate annealing during the hot rolling.  
   
   
       145 . The method of  claim 144 , further comprising recovery annealing thesheet after the cold rolling.  
   
   
       146 . The method of  claim 137 , further comprising cold working the solution heat treated sheet.  
   
   
       147 . The method of  claim 137 , wherein the aluminum alloy is an Al—Cu alloy comprising aluminum, from about 1 to about 5 weight percent Cu, up to about 6 weight percent Mg, up to about 1 weight percent Mn, and up to about 0.5 weight percent Zr.  
   
   
       148 . The method of  claim 147 , wherein the Al—Cu base alloy comprises at least about 3 weight percent Cu.  
   
   
       149 . The method of  claim 147 , wherein the Al—Cu base alloy includes from about 3.5 to about 4.5 weight percent Cu, from about 0.6 to about 1.6 weight percent Mg, from about 0.3 to about 0.7 weight percent Mn, and from about 0.08 to about 0. 13 weight percent Zr.  
   
   
       150 . The method of  claim 147 , wherein the Al—Cu base alloy includes from about 3.8 to about 4.4 weight percent Cu, from about 0.3 to about 0.7 weight percent Mn, from about 1.0 to about 1.6 weight percent Mg, and from about 0.09 to about 0.12 weight percent Zr.  
   
   
       151 . The method of  claim 147 , wherein the Al—Cu base alloy includes from about 3.4 to about 4.0 weight percent Cu, from 0 to about 0.4 weight percent Mn, from about 1.0 to about 1.6 weight percent Mg, and from about 0.09 to about 0.12 weight percent Zr.  
   
   
       152 . The method of  claim 147 , wherein the Al—Cu base alloy includes from about 3.2 to about 3.8 weight percent Cu, from about 0.3 to about 0.7 weight percent Mn, from about 1.0 to about 1.6 weight percent Mg, from about 0.09 to about 0.12 weight percent Zr, and from about 0.25 to about 0.75 weight percent Li.  
   
   
       153 . The method of  claim 137 , wherein the aluminum alloy is an Al—Mg base alloy comprising aluminum, from about 0.2 to about 7 weight percent Mg, from 0 to about 1 weight percent Mn, from 0 to about 1.5 weight percent Cu, from 0 to about 3 weight percent Zn, and from 0 to about 0.5 weight percent Si.  
   
   
       154 . The method of  claim 137 , wherein the aluminum alloy is an Al—Mg—Si base alloy comprising aluminum, from about 0.1 to about 2.5 weight percent Mg, from about 0.1 to about 2.5 weight percent Si, from 0 to about 2 weight percent Cu, from 0 to about 3 weight percent Zn, and from 0 to about 1 weight percent Li.  
   
   
       155 . The method of  claim 137 , wherein the aluminum alloy is an Al—Zn base alloy comprising aluminum, from about 1 to about 10 weight percent Zn, from about 0.1 to about 3 weight percent Cu, from about 0.1 to about 3 weight percent Mg, from 0 to about 2 weight percent Li, and from 0 to about 2 weight percent Ag.  
   
   
       156 . The method of  claim 137 , wherein the sheet product has a thickness of up to about 0.35 inch.  
   
   
       157 . The method of  claim 137 , wherein the sheet product is unrecrystallized.  
   
   
       158 . The method of  claim 157 , wherein the unrecrystallized sheet product has a Brass texture of greater than 20.  
   
   
       159 . The method of  claim 157 , wherein the unrecrystallized sheet product has a Brass texture of greater than 30.  
   
   
       160 . The method of  claim 157 , wherein the unrecrvstallized sheet product has a Brass texture of greater than 40.  
   
   
       161 . The method of  claim 137 , wherein the sheet product is recrystallized.  
   
   
       162 . The method of  claim 161 , wherein the recrystallized sheet product has a Goss texture of greater than 20.  
   
   
       163 . The method of  claim 161 , wherein the recrystallized sheet product has a Goss texture of greater than 30.  
   
   
       164 . The method of  claim 161 , wherein the recrystallized sheet product has a Goss texture of greater than 40.  
   
   
       165 . The method of  claim 101 , wherein the sheet product comprises unrecrystallized grains having a Brass texture of greater than 20 and/or recrystallized grains having a Goss texture of greater than 20.  
   
   
       166 . The method of  claim 165 , wherein the aluminum alloy is substantially free of Li, and comprises a maximum of 0.7 weight percent Mn and a maximum of 0.2 weight percent Si.  
   
   
       167 . The method of  claim 165 , wherein the aluminum alloy comprises from about 1 to about 5 weight percent Cu, up to about 6 weight percent Mg, up to about 0.7 weight percent Mn, up to about 0.5 weight percent Zr, up to about 0.2 weight percent Si, and is substantially free of Li.  
   
   
       168 . The method of  claim 165 , wherein the aluminum alloy is substantially free of Li, and comprises a maximum of 4.0 weight percent Cu and a maximum of 0.2 weight percent Si.  
   
   
       169 . The method of  claim 165 , wherein the aluminum alloy is substantially free of Li, and comprises a maximum of 4.0 weight percent Cu, a maximum of 0.7 weight percent Mn and a maximum of 0.2 weight percent Si.  
   
   
       170 . The method of  claim 137 , wherein the sheet product comprises unrecrystallized grains having a Brass texture of greater than 20 and/or recrystallized grains having a Goss texture of greater than 20.  
   
   
       171 . The method of  claim 170 , wherein the aluminum alloy is substantially free of Li, and comprises a maximum of 0.7 weight percent Mn and a maximum of 0.2 weight percent Si.  
   
   
       172 . The method of  claim 170 , wherein the aluminum alloy comprises from about 1 to about 5 weight percent Cu, up to about 6 weight percent Mg, up to about 0.7 weight percent Mn, up to about 0.5 weight percent Zr, up to about 0.2 weight percent Si, and is substantially free of Li.  
   
   
       173 . The method of  claim 170 , wherein the aluminum alloy is substantially free of Li, and comprises a maximum of 4.0 weight percent Cu and a maximum of 0.2 weight percent Si.  
   
   
       174 . The method of  claim 170 , wherein the aluminum alloy is substantially free of Li, and comprises a maximum of 4.0 weight percent Cu, a maximum of 0.7 weight percent Mn and a maximum of 0.2 weight percent Si.