WO2022086997A1 - Improved 7xxx aluminum alloys - Google Patents
Improved 7xxx aluminum alloys Download PDFInfo
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- WO2022086997A1 WO2022086997A1 PCT/US2021/055655 US2021055655W WO2022086997A1 WO 2022086997 A1 WO2022086997 A1 WO 2022086997A1 US 2021055655 W US2021055655 W US 2021055655W WO 2022086997 A1 WO2022086997 A1 WO 2022086997A1
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- sheet product
- aluminum alloy
- 7xxx aluminum
- 7xxx
- alloy sheet
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Links
- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 388
- 229910052802 copper Inorganic materials 0.000 claims abstract description 114
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 108
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 93
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 82
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 49
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 38
- 229910052742 iron Inorganic materials 0.000 claims abstract description 37
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 37
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 32
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 25
- 239000012535 impurity Substances 0.000 claims abstract description 22
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 18
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000000047 product Substances 0.000 claims description 266
- 238000000034 method Methods 0.000 claims description 42
- 238000001953 recrystallisation Methods 0.000 claims description 42
- 230000032683 aging Effects 0.000 claims description 38
- 238000012360 testing method Methods 0.000 claims description 34
- 239000002244 precipitate Substances 0.000 claims description 29
- 230000018199 S phase Effects 0.000 claims description 24
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 22
- 238000010791 quenching Methods 0.000 claims description 22
- 238000000137 annealing Methods 0.000 claims description 20
- 230000000171 quenching effect Effects 0.000 claims description 18
- 238000001816 cooling Methods 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 13
- 229910052796 boron Inorganic materials 0.000 claims description 9
- 239000003973 paint Substances 0.000 claims description 7
- 238000005097 cold rolling Methods 0.000 claims description 5
- 238000005098 hot rolling Methods 0.000 claims description 5
- 238000004299 exfoliation Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 230000035882 stress Effects 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 abstract description 78
- 239000000956 alloy Substances 0.000 abstract description 78
- 230000007797 corrosion Effects 0.000 abstract description 12
- 238000005260 corrosion Methods 0.000 abstract description 12
- 239000010949 copper Substances 0.000 description 70
- 239000011777 magnesium Substances 0.000 description 68
- 239000011572 manganese Substances 0.000 description 66
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 24
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 24
- 239000011651 chromium Substances 0.000 description 22
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 22
- 239000000463 material Substances 0.000 description 21
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 17
- 239000000203 mixture Substances 0.000 description 16
- 238000004458 analytical method Methods 0.000 description 14
- 239000010936 titanium Substances 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 238000013459 approach Methods 0.000 description 12
- 238000005266 casting Methods 0.000 description 12
- 238000005096 rolling process Methods 0.000 description 12
- 230000027311 M phase Effects 0.000 description 10
- 230000008569 process Effects 0.000 description 10
- 238000013001 point bending Methods 0.000 description 9
- 238000010583 slow cooling Methods 0.000 description 9
- 238000001887 electron backscatter diffraction Methods 0.000 description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- 241000616244 Thetys Species 0.000 description 6
- 239000011575 calcium Substances 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 5
- -1 i.e. Chemical compound 0.000 description 5
- 238000001000 micrograph Methods 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 229910052793 cadmium Inorganic materials 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 4
- 229910052744 lithium Inorganic materials 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 229910052706 scandium Inorganic materials 0.000 description 4
- 229910052709 silver Inorganic materials 0.000 description 4
- 229910052716 thallium Inorganic materials 0.000 description 4
- 239000012467 final product Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000011020 pilot scale process Methods 0.000 description 3
- 238000005482 strain hardening Methods 0.000 description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 229910052790 beryllium Inorganic materials 0.000 description 2
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000000265 homogenisation Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 229910052745 lead Inorganic materials 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 229910052712 strontium Inorganic materials 0.000 description 2
- BKVIYDNLLOSFOA-UHFFFAOYSA-N thallium Chemical compound [Tl] BKVIYDNLLOSFOA-UHFFFAOYSA-N 0.000 description 2
- RILZRCJGXSFXNE-UHFFFAOYSA-N 2-[4-(trifluoromethoxy)phenyl]ethanol Chemical compound OCCC1=CC=C(OC(F)(F)F)C=C1 RILZRCJGXSFXNE-UHFFFAOYSA-N 0.000 description 1
- 229910001203 Alloy 20 Inorganic materials 0.000 description 1
- QYEXBYZXHDUPRC-UHFFFAOYSA-N B#[Ti]#B Chemical compound B#[Ti]#B QYEXBYZXHDUPRC-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910033181 TiB2 Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 229940117975 chromium trioxide Drugs 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N chromium trioxide Inorganic materials O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- GAMDZJFZMJECOS-UHFFFAOYSA-N chromium(6+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Cr+6] GAMDZJFZMJECOS-UHFFFAOYSA-N 0.000 description 1
- 239000008119 colloidal silica Substances 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 230000010339 dilation Effects 0.000 description 1
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 235000012438 extruded product Nutrition 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
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- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 238000010200 validation analysis Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/10—Alloys based on aluminium with zinc as the next major constituent
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0273—Final recrystallisation annealing
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/053—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with zinc as the next major constituent
Definitions
- Aluminum alloys are useful in a variety of applications. However, improving one property of an aluminum alloy without degrading another property is elusive. For example, it is difficult to increase the strength of a wrought aluminum alloy without affecting other properties such as fracture toughness or corrosion resistance. 7xxx (Al — Zn — Mg based) are prone to corrosion. See, e.g., W. Gruhl, “The stress corrosion behaviour of high strength AlZnMg alloys,” Paper held at the International Meeting of Associazione Italiana di Metallurgie, “Aluminum Alloys in Aircraft Industries,” Turin, October 1976.
- the present patent application relates to new 7xxx aluminum alloys and products made from the same.
- the new 7xxx aluminum alloys generally comprise (and in some instance consist of, or consist essentially of) 5.0 - 9.0 wt. % Zn, 1.30 - 2.05 wt. % Mg, 1.10 - 2.10 wt. % Cu, wherein 2.55 ⁇ (wt. % Cu + wt. % Mg) ⁇ 3.85, at least one of (i) 0.03 - 0.40 wt. % Mn and 0.02 - 0.15 wt. % Zr, wherein 0.05 ⁇ (wt. % Zr + wt.
- a new 7xxx aluminum alloy includes 5.8 - 7.5 wt. % Zn, 1.50 - 2.0 wt. % Mg, 1.30 - 2.05 wt. % Cu, wherein 2.55 ⁇ (wt. % Cu + wt.
- % Mg ⁇ 3.80, at least one of (i) 0.03 - 0.40 wt. % Mn and 0.05 - 0.15 wt. % Zr, wherein 0.05 ⁇ (wt. % Zr + wt. % Mn) ⁇ 0.50, up to 0.20 wt. % Cr, up to 0.20 wt. % V, up to 0.20 wt. % Fe, up to 0.15 wt. % Si, up to 0.15 wt. % Ti, and up to 75 ppm B, the balance being aluminum, incidental elements and impurities.
- a new 7xxx aluminum alloy includes 6.0 - 7.0 wt.
- the new 7xxx aluminum alloy is in the form of a rolled 7xxx aluminum alloy sheet product having a thickness of from 0.5 to 4.0 mm.
- the 7xxx aluminum alloy sheet product comprises at least 15 vol. % recrystallized grains. In one embodiment, the 7xxx aluminum alloy sheet product comprises a dispersoid content of not greater than 1.95 vol. %, wherein the amount of dispersoids is calculated from the formula (wt. % Mn)*3.52 + (wt. % Zr)*1.28 + (wt. % Cr + wt. % V)*6.34. Products made from the new 7xxx aluminum alloys may realize an improved combination of properties, such as an improved combination of two or more of strength, ductility (elongation), fracture behavior and corrosion resistance.
- the new 7xxx aluminum alloys generally comprise 5.0 - 9.0 wt. % Zn.
- a 7xxx aluminum alloy includes at least 5.2 wt. % Zn.
- a 7xxx aluminum alloy includes at least 5.4 wt. % Zn.
- a 7xxx aluminum alloy includes at least 5.6 wt. % Zn.
- a 7xxx aluminum alloy includes at least 5.8 wt. % Zn.
- a 7xxx aluminum alloy includes at least 6.0 wt. % Zn.
- a 7xxx aluminum alloy includes at least 6.2 wt. % Zn.
- a 7xxx aluminum alloy includes at least 6.4 wt. % Zn.
- a 7xxx aluminum alloy includes at least 6.6 wt. % Zn.
- a 7xxx aluminum alloy includes not greater than 8.8 wt. % Zn. In another embodiment, a 7xxx aluminum alloy includes not greater than 8.6 wt. % Zn. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 8.4 wt. % Zn. In another embodiment, a 7xxx aluminum alloy includes not greater than 8.2 wt. % Zn. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 8.0 wt. % Zn. In another embodiment, a 7xxx aluminum alloy includes not greater than 7.8 wt. % Zn. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 7.6 wt. % Zn.
- a 7xxx aluminum alloy includes not greater than 7.5 wt. % Zn. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 7.4 wt. % Zn. In another embodiment, a 7xxx aluminum alloy includes not greater than 7.3 wt. % Zn. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 7.2 wt. % Zn. In another embodiment, a 7xxx aluminum alloy includes not greater than 7.1 wt. % Zn. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 7.0 wt. % Zn.
- the new 7xxx aluminum alloys generally comprise 1.30 - 2.05 wt. % Mg.
- a 7xxx aluminum alloy includes at least 1.35 wt. % Mg.
- a 7xxx aluminum alloy includes at least 1.40 wt. % Mg.
- a 7xxx aluminum alloy includes at least 1.45 wt. % Mg.
- a 7xxx aluminum alloy includes at least 1.50 wt. % Mg.
- a 7xxx aluminum alloy includes not greater than 2.0 wt. % Mg. In another embodiment, a 7xxx aluminum alloy includes not greater than 1.95 wt. % Mg. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 1.90 wt. % Mg. In another embodiment, a 7xxx aluminum alloy includes not greater than 1.85 wt. % Mg. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 1.80 wt. % Mg. In another embodiment, a 7xxx aluminum alloy includes not greater than 1.75 wt. % Mg. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 1.70 wt. % Mg. In another embodiment, a 7xxx aluminum alloy includes not greater than 1.65 wt. % Mg. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 1.60 wt. % Mg.
- the new 7xxx aluminum alloys generally comprise 1.10 - 2.10 wt. % Cu.
- a 7xxx aluminum alloy includes at least 1.15 wt. % Cu.
- a 7xxx aluminum alloy includes at least 1.20 wt. % Cu.
- a 7xxx aluminum alloy includes at least 1.25 wt. % Cu.
- a 7xxx aluminum alloy includes at least 1.30 wt. % Cu.
- a 7xxx aluminum alloy includes at least 1.35 wt. % Cu.
- a 7xxx aluminum alloy includes at least 1.40 wt. % Cu.
- a 7xxx aluminum alloy includes not greater than 2.05 wt. % Cu. In another embodiment, a 7xxx aluminum alloy includes not greater than 2.0 wt. % Cu. In another embodiment, a 7xxx aluminum alloy includes not greater than 1.95 wt. % Cu. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 1.90 wt. % Cu. In another embodiment, a 7xxx aluminum alloy includes not greater than 1.85 wt. % Cu. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 1.80 wt. % Cu. In another embodiment, a 7xxx aluminum alloy includes not greater than 1.75 wt. % Cu.
- a 7xxx aluminum alloy includes not greater than 1.70 wt. % Cu. In another embodiment, a 7xxx aluminum alloy includes not greater than 1.65 wt. % Cu. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 1.60 wt. % Cu.
- the combined amount of magnesium and copper used in the new 7xxx aluminum alloys is generally from 2.55 to 3.85 wt. %, i.e., 2.55 ⁇ (wt. % Cu + wt. % Mg) ⁇ 3.85.
- the combined amount of magnesium and copper is at least 2.60 wt. %, i.e., (wt. % Cu + wt. % Mg) is at least 2.60.
- the combined amount of magnesium and copper is at least 2.65 wt. %, i.e., (wt. % Cu + wt. % Mg) is at least 2.65.
- the combined amount of magnesium and copper is at least 2.70 wt. %, i.e., (wt. % Cu + wt. % Mg) is at least 2.70. In another embodiment, the combined amount of magnesium and copper is at least 2.75 wt. %, i.e., (wt. % Cu + wt. % Mg) is at least 2.75. In yet another embodiment, the combined amount of magnesium and copper is at least 2.80 wt. %, i.e., (wt. % Cu + wt. % Mg) is at least 2.80. In another embodiment, the combined amount of magnesium and copper is at least 2.85 wt. %, i.e., (wt.
- the combined amount of magnesium and copper is at least 2.90 wt. %, i.e., (wt. % Cu + wt. % Mg) is at least 2.90.
- the combined amount of magnesium and copper is at least 2.95 wt. %, i.e., (wt. % Cu + wt. % Mg) is at least 2.95.
- the combined amount of magnesium and copper is not greater than 3.80 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.80. In another embodiment, the combined amount of magnesium and copper is not greater than 3.75 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.75. In yet another embodiment, the combined amount of magnesium and copper in the 7xxx aluminum alloys is not greater than 3.70 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.70.
- the combined amount of magnesium and copper is not greater than 3.65 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.65. In yet another embodiment, the combined amount of magnesium and copper is not greater than 3.60 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.60. In another embodiment, the combined amount of magnesium and copper is not greater than 3.55 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.55. In yet another embodiment, the combined amount of magnesium and copper is not greater than 3.50 wt.
- the combined amount of magnesium and copper is not greater than 3.50.
- the combined amount of magnesium and copper is not greater than 3.45 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.45.
- the combined amount of magnesium and copper is not greater than 3.40 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.40.
- the combined amount of magnesium and copper is not greater than 3.35 wt. %, i.e., (wt. % Cu + wt.
- the combined amount of magnesium and copper is not greater than 3.35.
- the combined amount of magnesium and copper is not greater than 3.30 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.30.
- the combined amount of magnesium and copper is not greater than 3.25 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.25.
- the combined amount of magnesium and copper is not greater than 3.20 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.20.
- the combined amount of magnesium and copper is not greater than 3.15 wt. %, i.e., (wt. % Cu + wt. % Mg) is not greater than 3.15.
- a 7xxx aluminum alloy includes an amount of copper that is less than the amount of magnesium included in the 7xxx aluminum alloy, i.e., wt. % Cu ⁇ wt. % Mg.
- the new 7xxx aluminum alloys include at least one of 0.03 - 0.40 wt. % Mn and 0.02 - 0.15 wt. % Zr, wherein 0.05 ⁇ (wt. % Zr + wt. % Mn) ⁇ 0.50, i.e., the combined amount of manganese and zirconium is from 0.05 to 0.50 wt. %. In one embodiment, the combined amount of manganese and zirconium is at least 0.08 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.08 wt. %.
- the combined amount of manganese and zirconium is at least 0.10 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.10 wt. %. In yet another embodiment, the combined amount of manganese and zirconium is at least 0.12 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.12 wt. %. In another embodiment, the combined amount of manganese and zirconium is at least 0.14 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.14 wt. %.
- the combined amount of manganese and zirconium is at least 0.16 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.16 wt. %. In another embodiment, the combined amount of manganese and zirconium is at least 0.18 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.18 wt. %. In yet another embodiment, the combined amount of manganese and zirconium is at least 0.20 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.20 wt. %.
- the combined amount of manganese and zirconium is at least 0.22 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.22 wt. %. In yet another embodiment, the combined amount of manganese and zirconium is at least 0.24 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.24 wt. %. In another embodiment, the combined amount of manganese and zirconium is at least 0.26 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.26 wt. %.
- the combined amount of manganese and zirconium is at least 0.28 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.28 wt. %. In another embodiment, the combined amount of manganese and zirconium is at least 0.30 wt. %, i.e., (wt. % Zr + wt. % Mn) > 0.30 wt. %.
- the combined amount of manganese and zirconium is not greater than 0.45 wt. %, i.e., (wt. % Zr + wt. % Mn) ⁇ 0.45 wt. %. In another embodiment, the combined amount of manganese and zirconium is not greater than 0.40 wt. %, i.e., (wt. % Zr + wt. % Mn) ⁇ 0.40 wt. %. In yet another embodiment, the combined amount of manganese and zirconium is not greater than 0.38 wt. %, i.e., (wt. % Zr + wt. % Mn) ⁇ 0.38 wt. %.
- the new 7xxx aluminum alloys may include 0.02 - 0.15 wt. % Zr.
- a 7xxx aluminum alloy includes at least 0.08 wt. %. Zr.
- a new 7xxx aluminum alloy includes at least 0.10 wt. % Zr.
- the zirconium content is below the peritectic of the 7xxx aluminum alloy composition (e.g., to restrict/avoid primary particulates formed during casting, such as AhZr primary particulates).
- a new 7xxx aluminum alloy includes not greater than 0.13 wt. % Zr.
- a new 7xxx aluminum alloy includes not greater than 0.12 wt.
- a new 7xxx aluminum alloy includes not greater than 0.11 wt. % Zr.
- the new 7xxx aluminum alloys may include 0.03 - 0.50 wt. % Mn.
- a 7xxx aluminum alloy includes at least 0.08 wt. %. Mn.
- a new 7xxx aluminum alloy includes at least 0.10 wt. % Mn.
- a new 7xxx aluminum alloy includes at least 0.12 wt. % Mn.
- a new 7xxx aluminum alloy includes at least 0.15 wt. % Mn.
- a new 7xxx aluminum alloy includes at least 0.18 wt. % Mn. In another embodiment, a new 7xxx aluminum alloy includes at least 0.20 wt. % Mn. In yet another embodiment, a new 7xxx aluminum alloy includes at least 0.22 wt. % Mn. In another embodiment, a new 7xxx aluminum alloy includes at least 0.25 wt. % Mn.
- a 7xxx aluminum alloy includes not greater than 0.45 wt. % Mn. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.40 wt. % Mn. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.35 wt. % Mn. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.30 wt. % Mn. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.28 wt. % Mn.
- a 7xxx aluminum alloy includes 0.20-0.30 wt. % Mn. In one embodiment, a 7xxx aluminum alloy includes 0.08-0.13 wt. % Zr. In one embodiment, a 7xxx aluminum alloy includes 0.20-0.30 wt. % Mn and 0.08-0.13 wt. % Zr. In another embodiment, a 7xxx aluminum alloy includes 0.20-0.30 wt. % Mn and 0.08-0.12 wt. % Zr, wherein the zirconium content is below the peritectic of the 7xxx aluminum alloy composition. In yet another embodiment, a 7xxx aluminum alloy includes 0.20-0.30 wt. % Mn and 0.08-0.11 wt. % Zr, wherein the zirconium content is below the peritectic of the 7xxx aluminum alloy composition.
- the new 7xxx aluminum alloys may include up to 0.20 wt. % Cr.
- a 7xxx aluminum alloy includes from 0.05 to 0.20 wt. % Cr.
- a 7xxx aluminum alloy includes not greater than 0.15 wt. % Cr.
- a 7xxx aluminum alloy includes not greater than 0.10 wt. % Cr.
- a 7xxx aluminum alloy includes not greater than 0.08 wt. % Cr.
- a 7xxx aluminum alloy includes not greater than 0.05 wt. % Cr.
- a 7xxx aluminum alloy includes not greater than 0.04 wt. % Cr.
- a 7xxx aluminum alloy includes not greater than 0.03 wt. % Cr. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.02 wt. % Cr. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.01 wt. % Cr. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.005 wt. % Cr.
- the new 7xxx aluminum alloys may include up to 0.20 wt. % V.
- a 7xxx aluminum alloy includes from 0.05 to 0.20 wt. % V.
- a 7xxx aluminum alloy includes not greater than 0.15 wt. % V.
- a 7xxx aluminum alloy includes not greater than 0.10 wt. % V.
- a 7xxx aluminum alloy includes not greater than 0.08 wt. % V.
- a 7xxx aluminum alloy includes not greater than 0.05 wt. % V.
- a 7xxx aluminum alloy includes not greater than 0.04 wt. % V.
- a 7xxx aluminum alloy includes not greater than 0.03 wt. % V. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.02 wt. % V. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.01 wt. % V. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.005 wt. % V.
- the new 7xxx aluminum alloys may include up to 0.20 wt. % Fe.
- a 7xxx aluminum alloy includes at least 0.01 wt. % Fe.
- a 7xxx aluminum alloy includes at least 0.03 wt. % Fe.
- a 7xxx aluminum alloy includes at least 0.05 wt. % Fe.
- a 7xxx aluminum alloy includes at least 0.07 wt. % Fe.
- a 7xxx aluminum alloy includes at least 0.09 wt. % Fe.
- a 7xxx aluminum alloy includes not greater than 0.18 wt. % Fe. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.16 wt. % Fe. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.14 wt. % Fe. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.12 wt. % Fe. In some embodiments, iron is restricted to fairly low levels, which may facilitate improved bend properties. In one embodiment, a 7xxx aluminum alloy includes not greater than 0.10 wt. % Fe. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.08 wt. % Fe.
- a 7xxx aluminum alloy includes not greater than 0.06 wt. % Fe. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.05 wt. % Fe. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.04 wt. % Fe.
- the new 7xxx aluminum alloys may include up to 0.15 wt. % Si.
- a 7xxx aluminum alloy includes at least 0.01 wt. % Si.
- a 7xxx aluminum alloy includes at least 0.03 wt. % Si.
- a 7xxx aluminum alloy includes at least 0.05 wt. % Si.
- a 7xxx aluminum alloy includes not greater than 0.12 wt. % Si. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.10 wt. % Si. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.08 wt. % Si. In some embodiments, silicon is restricted to fairly low levels, which may facilitate improved bend properties. In one embodiment, a 7xxx aluminum alloy includes not greater than 0.07 wt. % Si. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.06 wt. % Si. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.05 wt. % Si. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.04 wt. % Si. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.03 wt. % Si.
- the new 7xxx aluminum alloys may include up to 0.15 wt. % Ti.
- a 7xxx aluminum alloy includes at least 0.005 wt. % Ti.
- a 7xxx aluminum alloy includes at least 0.01 wt. % Ti.
- a 7xxx aluminum alloy includes at least 0.015 wt. % Ti.
- a 7xxx aluminum alloy includes at least 0.020 wt. % Ti.
- a 7xxx aluminum alloy includes at least 0.025 wt. % Ti
- a 7xxx aluminum alloy includes not greater than 0.12 wt. % Ti. In another embodiment, a 7xxx aluminum alloy includes not greater than 0.10 wt. % Ti. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.08 wt. % Ti. In yet another embodiment, a 7xxx aluminum alloy includes not greater than 0.05 wt. % Ti.
- the new 7xxx aluminum alloys may include up to 75 ppm B (boron).
- the boron may be in the form of titanium diboride.
- a 7xxx aluminum alloy includes at least 1 ppm B.
- a 7xxx aluminum alloy includes at least 3 ppm B.
- a 7xxx aluminum alloy includes at least 5 ppm B.
- a 7xxx aluminum alloy includes at least 8 ppm B.
- a 7xxx aluminum alloy includes at least 10 ppm B.
- a 7xxx aluminum alloy includes not greater than 70 ppm B.
- a 7xxx aluminum alloy includes not greater than 60 ppm B.
- a 7xxx aluminum alloy includes not greater than 50 ppm B.
- a 7xxx aluminum alloy includes not greater than 40 ppm B.
- the new 7xxx aluminum alloys generally include the stated alloying ingredients, the balance being aluminum, optional incidental elements, and impurities.
- incident elements means those elements or materials, other than the above listed elements, that may optionally be added to the alloy to assist in the production of the alloy. Examples of incidental elements include casting aids, such as deoxidizers.
- Optional incidental elements may be included in the alloy in a cumulative amount of up to 1.0 wt. %.
- one or more incidental elements may be added to the alloy during casting to reduce or restrict (and in some instances eliminate) ingot cracking due to, for example, oxide fold, pit and oxide patches.
- deoxidizers These types of incidental elements are generally referred to herein as deoxidizers.
- deoxidizers include Ca, Sr, and Be.
- Ca calcium
- Sr calcium
- Be When calcium (Ca) is included in the alloy, it is generally present in an amount of up to about 0.05 wt. %, or up to about 0.03 wt. %.
- Ca is included in the alloy in an amount of about 0.001-0.03 wt % or about 0.05 wt. %, such as 0.001-0.008 wt. % (or 10 to 80 ppm).
- Strontium (Sr) may be included in the alloy as a substitute for Ca (in whole or in part), and thus may be included in the alloy in the same or similar amounts as Ca.
- Be beryllium
- some embodiments of the alloy are substantially Be-free.
- Be is included in the alloy, it is generally present in an amount of up to about 20 ppm.
- Incidental elements may be present in minor amounts, or may be present in significant amounts, and may add desirable or other characteristics on their own without departing from the alloy described herein, so long as the alloy retains the desirable characteristics described herein. It is to be understood, however, that the scope of this disclosure should not/cannot be avoided through the mere addition of an element or elements in quantities that would not otherwise impact on the combinations of properties desired and attained herein.
- the new 7xxx aluminum alloys may contain low amounts of impurities.
- a new 7xxx aluminum alloy includes not greater than 0.15 wt. %, in total, of the impurities, and wherein the aluminum alloy includes not greater than 0.05 wt. % of each of the impurities.
- a new 7xxx aluminum alloy includes not greater than 0.10 wt. %, in total, of the impurities, and wherein the aluminum alloy includes not greater than 0.03 wt. % of each of the impurities.
- the new 7xxx aluminum alloys are generally substantially free of lithium, i.e., lithium is included only as an impurity, and generally at less than 0.04 wt. % Li, or less than 0.01 wt. % Li.
- the new 7xxx aluminum alloys are generally substantially free of silver, i.e., silver is included only as an impurity, and generally at less than 0.04 wt. % Ag, or less than 0.01 wt. % Ag.
- the new 7xxx aluminum alloys are generally substantially free of lead, i.e., lead is included only as an impurity, and generally at less than 0.04 wt. % Pb, or less than 0.01 wt. % Pb.
- the new 7xxx aluminum alloys are generally substantially free of cadmium, i.e., cadmium is included only as an impurity, and generally at less than 0.04 wt. % Cd, or less than 0.01 wt. % Cd.
- the new 7xxx aluminum alloys are generally substantially free of thallium, i.e., thallium is included only as an impurity, and generally at less than 0.04 wt. % Tl, or less than 0.01 wt. % Tl.
- the new 7xxx aluminum alloys are generally substantially free of scandium, i.e., scandium is included only as an impurity, and generally at less than 0.04 wt. % Sc, or less than 0.01 wt. % Sc.
- the new 7xxx aluminum alloys are generally substantially free of nickel, i.e., nickel is included only as an impurity, and generally at less than 0.04 wt. % Ni, or less than 0.01 w
- the new 7xxx aluminum alloys may be produced by casting (e.g., direct chill casting or continuously casting) into an ingot or strip followed by appropriate processing to achieve a variety of tempers, such as one of a T temper, a W temper, an O temper, or an F temper as per ANSI H35.1 (2009).
- a new aluminum alloy is processed to a “T temper” (thermally treated), such as into any of a Tl, T2, T3, T4, T5, T6, T7, T8, T9 or T10 temper as per ANSI H35.1 (2009).
- T6 and T7 tempers may be particularly relevant.
- a method (100) may include casting (105) an ingot or strip of any of the aluminum alloys described in Section /, above. After casting, an ingot may be homogenized (110), which homogenization may include scalping, lathing or peeling (if needed). The homogenization step (110) may be skipped with continuously cast strips, such as those described in U.S. Patent No. 6,672,368. Next, the ingot/strip is then rolled (115) to final gauge. In one embodiment, the final gauge sheet product has a thickness of from 0.5 to 4.0 mm.
- the rolling step (115) generally includes hot rolling to an intermediate gauge (117) and then cold rolling to final gauge (121).
- An intermediate anneal (119) may optionally be completed between hot rolling (117) and cold rolling (121).
- the product may be solution heat treated and then rapidly quenched (125).
- the solution heat treating portion of this step (125) generally comprises heating the final gauge product to a temperature sufficient and for a time sufficient to dissolve a large volume fraction of precipitation hardened phases (e.g., q (eta) phase).
- the quenching portion of this step (125) generally involves cooling the solution heat treated material rapidly to less than 200°F (e.g., less than 100°F), and generally at a cooling rate of at least 100°F per second, such as by water immersion and/or spraying.
- the quench rate of step 125 is at least 1000°F per second.
- the quench rate of step 125 is at least 10,000°F per second.
- the material may be artificially aged (130), such as by heating to one or more temperatures within the range of 200- 450°F.
- the artificial aging comprises peak strength aging to a T6 temper.
- a peak strength aged temper is where a product realizes a strength within about 20 MPa ( ⁇ 3 ksi) of its peak strength, as determined by appropriate aging curves.
- the artificial aging comprises overaging to a T7 or T77 temper.
- An overaged temper is where a product is aged past peak strength and to a strength more than 20 MPa ( ⁇ 3 ksi) less than its peak strength, as determined by appropriate aging curves. Overaging may facilitate improved corrosion resistance.
- the artificial aging step (130) may be completed by the aluminum sheet manufacturer, or the artificial aging step (130) may be completed by an automotive manufacturer (e.g., as a part of paint baking).
- the artificial age step (130) is a two-step aging practice, optionally followed by a paint baking step, wherein the alloy is held at a first temperature for a first period of time and then held at a second temperature for a second period of time.
- the first temperature is within the range of 225-275°F and the first period of time is from 2 to 16 hours (e.g., from 6 to 10 hours).
- the second temperature is generally higher than the first temperature, e.g. from 25° to 100°F higher than the first temperature.
- the second temperature is within the range of 300-350°F and the second period of time is from 2 to 16 hours (e.g., from 6 to 10 hours).
- Two-step aging practices differ from conventional three-step aging practices, such as those described in U.S. Patent No. 6,972,110, because two-step aging practices only include two-steps, i.e., after conclusion of the second step there are no additional artificial aging steps applied to the product, except for an optional paint baking step.
- alternate processing is used.
- this embodiment 100’
- the same steps as FIG. 1 apply, except a new post-rolling anneal (200) is completed after the rolling step (115) and prior to the solution heat treatment and quenching step (125).
- the final gauge materials are annealed (200) at one or more anneal temperatures (210) within the range of from 525°F to 850°F and at one or more anneal times (220) within the range of from 0.5 to 50 hours.
- the anneal products are then slowly cooled to a temperature of not greater than 200°F at a cooling rate (230) of not greater than 500°F per minute.
- the time-temperature profile may be selected to achieve a desired amount of recrystallization in the final product, as described below.
- the new anneal process (200) facilitates partially recrystallized final products having from 15-95 vol. % recrystallized grains (240), as described in further detail below.
- Such tailored final products may realize an improved combination of properties, as shown by the examples herein.
- the annealing is completed via an induction furnace and corresponding induction heating.
- the anneal (200) is completed by heating a coil of the final gauge 7xxx sheet product to the anneal temperature (210) using an appropriate heat-up rate (212), after which the product is held at the anneal temperature for the anneal time (220).
- the coil may then be cooled by removing it from the furnace and allowing it to sit in ambient conditions until it reaches ambient temperature, i.e., is coil cooled.
- the coil cooling may result in the slow cooling rates (230) described herein.
- the anneal temperature (210) may be from 525°F to 850°F, depending on the amount of recrystallization and/or grain size desired in the final product. Grain size is defined in the Definitions section, below. In cases where the microstructure is partially recrystallized, grain size refers to values obtained considering both recrystallized and unrecrystallized grains. Multiple anneal temperatures within the above-noted temperature range may be selected. In one embodiment, the anneal temperature is at least 575°F. In another embodiment, the anneal temperature is at least 625°F. In yet another embodiment, the anneal temperature is at least 675°F. In one embodiment, the anneal temperature is not greater than 825°F.
- the anneal temperature is not greater than 775°F. In one embodiment, the anneal temperature is from 650-800°F. In another embodiment, the anneal temperature is from 675-750°F.
- the heat-up rate (212) may be any suitable heat-up rate that facilitates achievement of the appropriate amount and/or size of recrystallized grains, such as any of the heat-up rates described in Example 1, Table 2, below. In one embodiment, the anneal heat-up rate (as measured from ambient temperature until the product is within 10°F of the anneal temperature) is from 25° to 50°C per hour (linear calculation employed for ease of determination).
- the anneal time (220) may be from 0.5 to 50 hours, depending on the amount of recrystallization and/or grain size desired in the final product, and multiple anneal times may be selected. In one embodiment, the anneal time is at least 1 hour. In another embodiment, the anneal time is at least 2 hours. In one embodiment, the anneal time is not greater than 40 hours. In another embodiment, the anneal time is not greater than 30 hours.
- the anneal cooling rate (230) is generally not greater than 500°F per minute as measured by the time it takes the material to cool from the anneal temperature (210) to 200°F. In one embodiment, the anneal cooling rate (230) is not greater than 100°F per minute. In another embodiment, the anneal cooling rate (230) is not greater than 10°F per minute. In yet another embodiment, the anneal cooling rate (230) is not greater than 5°F per minute. In another embodiment, the anneal cooling rate (230) is not greater than 2°F per minute. As noted above, the anneal cooling rate (230) may be accomplished by coil cooling.
- the new anneal process (200) facilitates partially recrystallized final products having from 15-95 vol. % recrystallized grains (240), as described in further detail below.
- the annealing process (200) produces materials having at least 20 vol. % recrystallized grains. In another embodiment, the annealing process (200) produces materials having at least 25 vol. % recrystallized grains.
- the annealing process (200) produces materials having not greater than 95 vol. % recrystallized grains. In another embodiment, the annealing process (200) produces materials having not greater than 90 vol. % recrystallized grains. In yet another embodiment, the annealing process (200) produces materials having not greater than 85 vol. % recrystallized grains. In another embodiment, the annealing process (200) produces materials having not greater than 80 vol. % recrystallized grains. In yet another embodiment, the annealing process (200) produces materials having not greater than 75 vol. % recrystallized grains. In another embodiment, the annealing process (200) produces materials having not greater than 70 vol. % recrystallized grains.
- an anneal (200) may be completed after rolling (115) and prior to solution heat treating (125) to produce 7xxx sheet products having tailored amounts of recrystallized grains and/or a tailored average grain size.
- tailoring the amount of recrystallization and/or grain size may facilitate the realization of an improved combination of properties, such as an improved combination of at least two of strength, elongation, fracture behavior (evaluated using the three-point bending test described herein), and corrosion resistance.
- a method (300) includes preselecting an amount of recrystallization (305) to achieve in a rolled 7xxx sheet product.
- the preselected amount of recrystallization may be 15-95% recrystallization (308), or any of the recrystallization amounts described in the preceding paragraphs.
- the method (300) further includes, at least partially based on the recrystallization preselecting step (305), preselecting the anneal conditions (315) to complete relative to the rolled 7xxx sheet product, which preselected anneal conditions include preselecting one or more anneal temperatures (317) and/or one or more anneal times (319) to be used for the anneal (200).
- a preselected heat-up rate (318) may also be selected, which heat-up rate may affect the amount of recrystallization and/or average grain size of the microstructure.
- a preselected anneal quench rate (321) may also be selected.
- the method may further comprise completing the anneal (200) using the preselected anneal conditions (315).
- the rolled 7xxx sheet product may realize (325) the selected amount of recrystallization (i.e., amount of recrystallized grains), such as any of the recrystallization amounts described in the preceding paragraph.
- a grain size may be preselected, such as any of the grain sizes shown in Example 1, Table 3, below.
- the rolled 7xxx sheet product may realize the preselected grain size.
- Alloy E of Example 1 achieved a 70% recrystallized microstructure by heating to 625°F at a heat-up rate of 60.9°F/hour (linear), holding at 625°F for 2 hours followed by slow cooling to room temperature, followed by solution heat treating at 870°F for 7 minutes followed by water quenching.
- recrystallized grains are generally homogenously intermixed with unrecrystallized grains through the thickness. This is completely different than known unrecrystallized sheet products where some recrystallized grains may be found near the surface but the interior is unrecrystallized.
- the grain size of the micro structure of FIG. 4 was 56.4 micrometers (includes both recrystallized and unrecrystallized grain sizes).
- a 99% recrystallized microstructure was achieved in Alloy G by heating to 525°F at a heat-up rate of 49.8°F/hour (linear), holding at 525°F for 24 hours, followed by slow cooling to room temperature, followed by solution heat treating at 870°F for 7 minutes followed by water quenching.
- the grain size of the microstructure of FIG. 5 was 65.2 micrometers.
- a 60% recrystallized microstructure was achieved in Alloy E by heating to 725°F at a heat-up rate of 72.0°F/hour (linear), holding at 725°F for 2 hours, followed by slow cooling to room temperature, followed by solution heat treating at 870°F for 7 minutes followed by water quenching.
- the grain size of the microstructure of FIG. 6 was 67.1 micrometers. Upon subsequent aging, this microstructure realizes an improved combination of mechanical properties (see Example 1 below).
- the final gauge sheet product is solution heat treated and quenched (125).
- the solution heat treating and quenching step is accomplished by the manufacturer of the final gauge 7xxx aluminum alloy sheet product, after which the product is either (i) shipped to the customer (e.g., in the W-temper) or (ii) is artificially aged (130), as described above, and then shipped to the customer.
- the manufacturer of the final gauge 7xxx aluminum alloy sheet product ships the final gauge 7xxx aluminum alloy sheet product in the F temper (as fabricated) or O temper (as annealed) to a customer, such as an automotive manufacturer, who completes the solution heat treating and quenching step (125) and any artificial aging step (130).
- the customer completes the solution heat treating and quenching step (125) as part of a hot forming operation, wherein the final gauge 7xxx aluminum alloy sheet product is heated to a solution heat treatment temperature and then formed into a component (e.g., an automotive component).
- the tooling used to form the final gauge 7xxx aluminum alloy sheet product into the component generally deforms the material into a complex shape.
- the hot forming comprises forming the final gauge 7xxx aluminum alloy sheet product in one or more dies.
- the tooling temperature may be substantially below the solution heat treatment temperature.
- quenching of the final gauge 7xxx aluminum alloy sheet product may occur due to contact contact with the tooling.
- the tooling can be water or air cooled.
- the formed 7xxx aluminum alloy sheet product may then be artificially aged (130) in one or more steps.
- at least one of the artificial aging steps includes paint baking (e.g., for 20-40 minutes at 180-190°C).
- the 7xxx aluminum alloy products may realize a unique microstructure, which may at least partially give rise to the unique properties shown herein.
- the 7xxx aluminum alloys may be partially recrystallized or fully recrystallized.
- “partially recrystallized” means a product realizes 15-95% recrystallization (i.e., contains 15-95 vol. % recrystallized grains), as determined using the Recrystallization Determination Procedure, described in the Definitions section, below.
- a fully recrystallized product is 96-100% recrystallized (i.e., contains 96-100 vol. % recrystallized grains), as determined using the Recrystallization Determination Procedure, described in the Definitions section, below.
- the 7xxx aluminum alloy product is a fully recrystallized sheet product. In another embodiment, the 7xxx aluminum alloy product is a partially recrystallized sheet product having 15-95 vol. % recrystallized grains. In one embodiment, a partially recrystallized 7xxx aluminum alloy sheet product comprises at least 20 vol. % recrystallized grains. In another embodiment, a partially recrystallized 7xxx aluminum alloy sheet product comprises at least 25 vol. % recrystallized grains. In yet another embodiment, a partially recrystallized 7xxx aluminum alloy sheet product comprises at least 30 vol. % recrystallized grains. In another embodiment, a partially recrystallized 7xxx aluminum alloy sheet product comprises at least 35 vol. % recrystallized grains.
- a partially recrystallized 7xxx aluminum alloy sheet product comprises not greater than 90 vol. % recrystallized grains. In another embodiment, a partially recrystallized 7xxx aluminum alloy sheet product comprises not greater than 85 vol. % recrystallized grains. In yet another embodiment, a partially recrystallized 7xxx aluminum alloy sheet product comprises not greater than 80 vol. % recrystallized grains. In another embodiment, a partially recrystallized 7xxx aluminum alloy sheet product comprises not greater than 75 vol. % recrystallized grains. In yet another embodiment, a partially recrystallized 7xxx aluminum alloy sheet product comprises not greater than 70 vol. % recrystallized grains.
- a 7xxx aluminum alloy sheet product from 30 to 80 vol. % recrystallized grains. In another embodiment, a 7xxx aluminum alloy sheet product comprises from 35 to 75 vol. % recrystallized grains.
- the 7xxx aluminum alloy products may contain an appropriate amount of dispersoids, wherein the amount of dispersoids is calculated from the formula (wt. % Mn)*3.52 + (wt. % Zr)*1.28 + (wt. % Cr + wt. % V)*6.34.
- a 7xxx aluminum alloy sheet product comprises from 0.07 to 1.95 vol. % of dispersoids.
- a 7xxx aluminum alloy sheet product comprises at least 0.08 vol. % dispersoids.
- a 7xxx aluminum alloy sheet product comprises at least 0.09 vol. % dispersoids.
- a 7xxx aluminum alloy sheet product comprises at least 0.10 vol. % dispersoids.
- a 7xxx aluminum alloy sheet product comprises at least 0.11 vol. % dispersoids. In yet another embodiment, a 7xxx aluminum alloy sheet product comprises at least 0.12 vol. % dispersoids. In another embodiment, a 7xxx aluminum alloy sheet product comprises at least 0.13 vol. % dispersoids.
- a 7xxx aluminum alloy sheet product comprises not greater than 1.90 vol. % dispersoids. In another embodiment, a 7xxx aluminum alloy sheet product comprises not greater than 1.85 vol. % dispersoids. In yet another embodiment, a 7xxx aluminum alloy sheet product comprises not greater than 1.80 vol. % dispersoids. In another embodiment, a 7xxx aluminum alloy sheet product comprises not greater than 1.70 vol. % dispersoids. In another embodiment, a 7xxx aluminum alloy sheet product comprises not greater than 1.60 vol. % dispersoids. In yet another embodiment, a 7xxx aluminum alloy sheet product comprises not greater than 1.50 vol. % dispersoids. In another embodiment, a 7xxx aluminum alloy sheet product comprises not greater than 1.40 vol.
- a 7xxx aluminum alloy sheet product comprises not greater than 1.30 vol. % dispersoids. In another embodiment, a 7xxx aluminum alloy sheet product comprises not greater than 1.20 vol. % dispersoids. In yet another embodiment, a 7xxx aluminum alloy sheet product comprises not greater than 1.10 vol. % dispersoids. In one approach, a 7xxx aluminum alloy sheet product comprises 0.80 to 1.20 vol. % dispersoids.
- the 7xxx aluminum alloy sheet products may contain precipitate hardening phases.
- a 7xxx aluminum alloy sheet product contains at least one of M-phase and S-phase precipitates.
- a 7xxx aluminum alloy sheet product is absent of T- phase precipitates. The presence or absence of M-phase, S-phase and T-phase precipitates, and their corresponding solvus temperature(s), is to be determined using THERMO-CALC software s : // w w . therm oc al c .
- a 7xxx aluminum alloy sheet product at least contains M-phase precipitates and the M-phase precipitates have a solvus temperature in the range of 744-810°F (395.6-413.9°C).
- a 7xxx aluminum alloy sheet product contains both M-phase and S-phase precipitates and the S-phase precipitates of the 7xxx aluminum alloy sheet product have a solvus temperature of not greater than 850°F (454.4°C).
- the S- phase precipitates have a solvus temperature of not greater than 845°F.
- the S-phase precipitates have a solvus temperature of not greater than 840°F.
- the S-phase precipitates have a solvus temperature of not greater than 835°F.
- the S-phase precipitates have a solvus temperature of not greater than 830°F.
- the S-phase precipitates have a solvus temperature of not greater than 825°F. In one embodiment, the S-phase precipitates have a solvus temperature of not greater than 820°F. In another embodiment, the S-phase precipitates have a solvus temperature of not greater than 815°F. In yet another embodiment, the S-phase precipitates have a solvus temperature of not greater than 810°F. In another embodiment, the S-phase precipitates have a solvus temperature of not greater than 805°F. In yet another embodiment, the S-phase precipitates have a solvus temperature of not greater than 800°F. In another embodiment, the S-phase precipitates have a solvus temperature of not greater than 795°F.
- a 7xxx aluminum alloy sheet product contains both M-phase and S-phase precipitates, the M-phase precipitates have a solvus temperature in the range of 744-810°F (395.6-413.9°C), the S-phase precipitates of the 7xxx aluminum alloy sheet product have a solvus temperature of not greater than 850°F (454.4°C), such as any of the solvus temperatures described above, and the 7xxx aluminum alloy sheet product is absent of T-phase precipitates.
- the new 7xxx aluminum alloys may realize an improved combination of properties, such as an improved combination of two or more of strength, ductility, fracture behavior (e.g., as evaluated using a three-point bending test), and corrosion resistance.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a tensile yield strength (LT) of at least 450 MPa.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a tensile yield strength (LT) of at least 460 MPa.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a tensile yield strength (LT) of at least 470 MPa.
- the above strength values are consistent with continuously cast materials.
- a 7xxx aluminum alloy sheet product is cast as an ingot (e.g., using DC (direct-chill) or electromagnetic casting) and then wrought processed to a final gauge material having a thickness of from 0.5 to 4.0 mm.
- the strength values may be higher.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a tensile yield strength (LT) of at least 480 MPa.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a tensile yield strength (LT) of at least 490 MPa.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a tensile yield strength (LT) of at least 500 MPa. In another embodiment, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a tensile yield strength (LT) of at least 510 MPa. In yet another embodiment, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a tensile yield strength (LT) of at least 520 MPa.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a tensile yield strength (LT) of at least 530 MPa. In yet another embodiment, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a tensile yield strength (LT) of at least 540 MPa, or higher.
- a 7xxx aluminum alloy sheet product has a thickness of 0.5 to 4.0 mm and is capable of realizing a three-point bend extension of at least 5.8 mm as per the “three- point bending test” described in the De Anlagens section, below. As noted below, all three-point bend testing is to be conducted at 2.0 ⁇ 0.05 mm.
- the bend extension for such a product is determined by reproducing the product at 2.0 ⁇ 0.05 mm, after which its three- point bend extension is measured.
- a 7xxx aluminum alloy sheet product realizes a three-point bend extension of at least 6.0 mm.
- a 7xxx aluminum alloy sheet product realizes a three-point bend extension of at least 6.1 mm. In another embodiment, a 7xxx aluminum alloy sheet product realizes a three-point bend extension of at least 6.2 mm. In yet another embodiment, a 7xxx aluminum alloy sheet product realizes a three-point bend extension of at least 6.3 mm. In another embodiment, a 7xxx aluminum alloy sheet product realizes a three-point bend extension of at least 6.4 mm. In yet another embodiment, a 7xxx aluminum alloy sheet product realizes a three-point bend extension of at least 6.5 mm. In another embodiment, a 7xxx aluminum alloy sheet product realizes a three-point bend extension of at least 6.6 mm.
- the above three-point bend extension values are consistent with continuously cast materials.
- a 7xxx aluminum alloy sheet product is cast as a DC ingot and then wrought processed to a final gauge material having a thickness of from 0.5 to 4.0 mm.
- a 7xxx aluminum alloy sheet product is cast as an ingot (e.g., using DC (direct- chill) or electromagnetic casting) and then wrought processed to a final gauge material having a thickness of from 0.5 to 4.0 mm, in which case the three-point bend extension values may be higher.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 6.7 mm.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 6.8 mm. In yet another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 7.0 mm. In another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 7.2 mm. In yet another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 7.4 mm.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 7.6 mm. In yet another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three- point bend extension of at least 7.8 mm. In another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 8.0 mm. In yet another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 8.2 mm.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 8.4 mm. In yet another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 8.6 mm. In another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three- point bend extension of at least 8.8 mm. In yet another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 9.0 mm.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 9.2 mm. In yet another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 9.4 mm. In another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 9.5 mm. In yet another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 9.6 mm.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 9.7 mm. In yet another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 9.8 mm. In another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three- point bend extension of at least 9.9 mm. In yet another, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes a three-point bend extension of at least 10.0 mm.
- Z is 15.25.
- Z is 15.5.
- Z is 15.75.
- Z is 16.0.
- Z is 16.25.
- Z is 16.5.
- Z is 16.75.
- the three-point bend extension would be at least 7.0 mm.
- the TYS(LT) would be at least 482 MPa (LT).
- Z is 27.0. In another embodiment, Z is 27.25. In yet another embodiment, Z is 27.5. In another embodiment, Z is 27.75. In yet another embodiment, Z is 28.0. In another embodiment, Z is 28.25. In yet another embodiment, Z is 28.5.
- the three-point bend extension would be at least 7.9 mm.
- the TYS(LT) would be at least 483 MPa (LT).
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes an exfoliation rating of at least EB when tested in accordance with ASTM G34-01(2018).
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes an exfoliation rating of at least EA when tested in accordance with ASTM G34-01(2018).
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes an exfoliation rating of at least P when tested in accordance with ASTM G34-01(2018).
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and passes at least 20 days of ASTM G44-99(2013) testing in the LT direction at a net stress of 353 MPa, wherein all 5 specimens of the 7xxx aluminum alloy sheet survive the ASTM G44 testing for 20 days.
- a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes an average depth of attack of not greater than 50 micrometers when tested in accordance with ASTM G110-92(2015) for 6 hours. In another embodiment, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes an average depth of attack of not greater than 40 micrometers when tested in accordance with ASTM G110-92(2015) for 6 hours. In another embodiment, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes an average depth of attack of not greater than 30 micrometers when tested in accordance with ASTM G110-92(2015) for 6 hours. In another embodiment, a 7xxx aluminum alloy sheet product has a thickness of from 0.5 to 4.0 mm and realizes an average depth of attack of not greater than 25 micrometers when tested in accordance with ASTM G110-92(2015) for 6 hours.
- the new aluminum alloys described herein may be used in a variety of product applications, such as in automotive and/or industrial applications.
- the new alloys may be used in body-in-white components or other structural components of an automobile (e.g., B-pillars, door beams, roof rails).
- “Wrought aluminum alloy product” means an aluminum alloy product that is hot worked after casting, and includes rolled products (sheet or plate), forged products, and extruded products.
- Hot working such as by hot rolling means working the aluminum alloy product at elevated temperature, and generally at least 250°F. Strain-hardening is restricted / avoided during hot working, which generally differentiates hot working from cold working.
- Cold working such as by cold rolling means working the aluminum alloy product at temperatures that are not considered hot working temperatures, generally below about 250°F (e.g., at ambient).
- Temper definitions are per ANSI H35.1 (2009), entitled “American National Standard Alloy and Temper Designation Systems for Aluminum,” published by The Aluminum Association.
- “Three-point bending tests” (sometimes called 3 -point bending tests) are measured in accordance with VDA 238-100, entitled, Plate bending test for metallic materials, Validation Rule, 01 June 2017 (see https://www.vda.de/en/servicesZPublications/vda-238-100- plate-bending-test-for-metailic-materials.html), where the final gauge (thickness) of the sheet is 2.0 ⁇ 0.05 mm, the coupon is fixed in the test frame, and a punch radius of 0.2 mm is used, except the VDA test is modified as follows: the specimen size is 25 mm wide and 51 mm long; • the extension at 70% load drop is used as a metric, with higher extensions representing greater fracture toughness or crash resistance (the normal test VDA 238-100 utilizes the bend angle measured after 5% drop in load as a metric for comparing materials).
- L Longitudinal
- LT transverse
- Percent recrystallized and the like means the volume percent of a wrought aluminum alloy product having recrystallized grains.
- the amount of recrystallized grains is determined by EBSD (electron backscatter diffraction) analysis of a suitable number of SEM micrographs of the wrought aluminum alloy product, as per the Recrystallization Determination Procedure, below. Generally at least 5 micrographs should be analyzed.
- Recrystallized grains means those grains of a crystalline microstructure that meet the “first grain criteria”, defined below, and as measured using the OIM (Orientation Imaging Microscopy) sampling procedure, described below.
- the OIM analysis is to be completed through the full thickness of the sheet sample on the L-ST plane, using the OIM sample procedure, below.
- the size of the sample to be analyzed will generally vary by gauge.
- the OIM samples Prior to measurement, the OIM samples are prepared by standard metallographic sample preparation methods. For example, the OIM samples are metallographically prepared and then polished (e.g., using 0.05 micron colloidal silica). The samples are then anodized in Barker’s reagent, a diluted fluoroboric acid solution, for 90 seconds. The samples are then stripped using an aqueous phosphoric acid solution containing chromium trioxide, and then rinsed and dried.
- the software used is OIM Data Collection Software version 7 (ED AX Inc., New Jersey, U.S.A.), or equivalent, which is connected to a Hikari EBSD camera (EDAX Inc., New Jersey, U.S.A.), or equivalent.
- the SEM is an APREO S Field Emission Gun (Thermo Fisher Scientific. Waltham, MA, U.S.A.), or equivalent.
- OIM run conditions are 65° tilt with a 17 mm working distance and an accelerating voltage of 20 kV with dynamic focusing and an instrument- specified beam current of 13 nA (nanoamps).
- the mode of collection is hexagonal grid. A selection is made such that orientations are collected in the analysis (i.e., Hough peaks information is not collected).
- the area size per scan i.e., the frame
- the collected data is output in an *.osc file. This data may be used to calculate the volume fraction of first type grains, as described below.
- volume fraction of first type grains is calculated using the data of the *.osc file and the OIM/TSL Analysis Software version 8, or equivalent. Prior to calculation, two-step data cleanup may be performed. First, for any points whose confidence index is below a threshold of 0.08, a neighbor orientation correlation clean-up is performed. Second, a grain dilation clean-up is performed for any grain smaller than 3 data points. Then, the amount of first type grains is calculated by the software using the first grain criteria (below).
- GAM Grain average misorientation
- First grain volume means the volume fraction of first type grains of the crystalline material.
- the term “grain” has the meaning defined in ASTM El 12 ⁇ 3.2.2, i.e., “the area within the confines of the original (primary) boundary observed on the two-dimensional plane of-polish or that volume enclosed by the original (primary) boundary in the three-dimensional object”.
- A/ is the area of the individual grain as measured using commercial software OIM/TSL version 8.0 or equivalent;
- A is the area of each individual grain as measured using commercial software Edax OIM version 8.0 or equivalent;
- d-bar is the area weighted average grain size.
- FIG. l is a flow chart showing one embodiment of a method for making rolled 7xxx aluminum alloy sheet products.
- FIG. 2 is a flow chart showing another embodiment of a method for making rolled 7xxx aluminum alloy sheet products.
- FIG. 3 is a flow chart showing one embodiment of a preselecting step relating to the anneal step (200) of FIG. 2.
- FIG. 4 is a micrograph showing a Kernel Average Misorientation (KAM) map from EBSD analyses of the grain structures of Alloy E of Example 1. This image is from a rolled 7xxx aluminum alloy sheet annealed at 625°F for 2 hours, followed by slow cooling to room temperature, followed by solution heat treating at 870°F for 7 minutes followed by water quenching.
- KAM Kernel Average Misorientation
- FIG. 5 is a micrograph showing Kernel Average Misorientation (KAM) maps from EBSD analyses of the grain structures of Alloy G of Example 1. This image is from a rolled 7xxx aluminum alloy sheet annealed at 525°F for 24 hours, followed by slow cooling to room temperature, followed by solution heat treating at 870°F for 7 minutes followed by water quenching.
- KAM Kernel Average Misorientation
- FIG. 6 is a micrograph showing a Kernel Average Misorientation (KAM) map from EBSD analyses of the grain structures of Alloy E of Example 1. This image is from a rolled 7xxx aluminum alloy sheet annealed at 725°F for 2 hours, followed by slow cooling to room temperature, followed by solution heat treating at 870°F for 7 minutes followed by water quenching.
- KAM Kernel Average Misorientation
- FIG. 7 is a micrograph showing Kernel Average Misorientation (KAM) maps from EBSD analyses of the grain structures of Alloy G of Example 1. This image is from a rolled 7xxx aluminum alloy sheet annealed at 725°F for 2 hours, followed by slow cooling to room temperature, followed by solution heat treating at 870°F for 7 minutes followed by water quenching.
- KAM Kernel Average Misorientation
- alloys I and M contained about 10 ppm of boron; alloy I contained about 40 ppm of boron; alloy M contained about 120 ppm of boron.
- All alloys were continuously cast on a pilot scale version of the apparatus described in commonly-owned U.S. Patent No. 6,672,368, which is incorporated herein by reference in its entirely. Specifically, the alloys were cast to a gauge of from 0.156-0.166 inch (3.964-4.216 mm) at a casting rate of about 53-57 feet per minute (16.2-17.4 meters per minute) and then hot rolled in-line to an intermediate gauge of about 0.125 inch (3.175 mm) and then cooled to room temperature. The intermediate gauge products were then subjected to an intermediate anneal and then cold rolled to a final gauge of about 0.080 inch (2.032 mm).
- the cold rolled products were then subjected to various post-rolling anneal conditions (shown in Table 2, below). After the post-rolling anneal was completed, the products were slow cooled by turning off the furnace and then removing the products from the furnace once the temperature reached about 300°F (148.9°C), after which the products were allowed to air cool to ambient (room) temperature.
- the final gauge products were artificially aged to a T7-type temper by first aging for 8 hours at 250°F (121.1°C) and then aging at 320°F (160°C) for either 8 or 16 hours. After aging, the products were subjected to various analyses, including mechanical property analyses. [00101] As it relates to mechanical properties, strength and elongation in the transverse orientation (LT) were tested at various final anneal and artificial aging conditions in accordance with ASTM E8/E8M-16a and B557-15. Duplicate specimens were used for all strength/elongation testing. The results are provided in the Table 4, below.
- Fracture behavior was also evaluated using three-point bending tests (as defined in the Definitions section), the test results of which are provided in Table 4, below. The tests were conducted relative to the transverse orientation (LT), and the reported values are based on the average of ten specimens used for each alloy tested.
- the invention alloys are capable of achieving a tensile yield strength (LT) of at least 450 MPa and a three-point bend extension of at least 5.8 mm.
- Alloy E is particularly high performing, realizing a very high combination of strength and three-point bend extension. It is hypothesized that Alloy E’s microstructural features (e.g., its grain size, percent recrystallization, amount of Zr-bearing and Mn-bearing intermetallic particles), facilitates realization of the excellent properties.
- Corrosion tests were also conducted on two alloys. Specifically, ASTM G34, G44 and ASTM G110 tests were conducted on specimens of Alloys E and G made in accordance with the production flow path shown in FIG. 1. Tables 5-7 show the results. All results are from artificial aging at 250°F (121.1°C) for 8 hours followed by artificial aging at 320°F (160°C) at 8 hours. As shown, the alloys exhibit good corrosion resistance properties. In the case of ASTM G44 testing (Table 6), the test was discontinued after 60 days, at which time two of the Alloy E samples had not failed.
- Dispersoid (vol. %) (wt. % Mn)*3.52 + (wt. % Zr)*1.28 + (wt. % Cr + wt. % V)*6.34
- the invention alloys contain a dispersoid content based on Mn, Zr, Cr, and V of from about 0.13 to 1.02 vol. %.
- Non-invention alloys J and K contain a high amount of dispersoids.
- the invention alloys when present, have an S-phase solvus temperature in the range of 770-825°F (410-440.6°C), an M-phase solvus temperature in the range of 744- 810°F (395.6-413.9°C), and have no T-phase precipitates. Conversely, some non-invention alloys may have an S-phase solvus temperature above 825°F (440.6°C) and/or contain T-phase precipitates.
- the ingots were homogenized and then hot rolled to 4.06 mm (0.160 inch). Some sheet samples annealed at 343.3°C (650°F) for 1 hour and then cold rolled to a final gauge of 2.03 mm (0.80 inch), while other samples skipped annealing and were simply cold rolled to the final gauge of 2.03 mm (0.80 inch). All final gauge samples were then solution heat treated, then cold water quenched, and then naturally aged for about 4 days. The naturally aged samples were then two-step artificially aged by first aging at 121.1°C (250°F) for 8 hours and then aging at 160°C (320°F) for 16 hours. After artificial aging, the products were subjected to various analyses, including mechanical property analyses.
- Example 2 As with Example 1, the mechanical properties, strength and elongation in the transverse orientations (LT) of the Example 2 alloys were tested in accordance with ASTM E8/E8M-16a and B557-15. Duplicate specimens were used for all strength/elongation testing. The results are provided in the Tables 11 and 12, below for the cases of no hot line anneal and with hot line anneal, respectively.
- Fracture behavior was also evaluated using three-point bending tests (as defined in the Definitions section), the test results of which are provided in Table 11, below. As with Example 1, the tests were conducted relative to the transverse orientation (LT), and the reported values are based on the average of ten specimens used for each alloy tested.
- alloys 2, 3, 4 and 7 realize an inferior strength/bend relationship. Alloys 2 and 3 are higher in iron and silicon than the others and therefore would not be expected to show excellent performance. Similarly, Alloy 4 had higher zirconium, and was determined to be beyond the peritectic composition (using the THERMO-CALC Aluminum Database, Version 5, “TCAL5,” based on alloy composition), which may have contributed to the formation of primary AhZr particles, which negatively affect performance. Alloy 7 contained a high amount of dispersoids.
- Example 2 alloys were also conducted on the Example 2 alloys fabricated using no hot line anneal and aged as described above.
- ASTM G44 all Example 2 alloys received a rating of EA after 2 days of test.
- ASTM G110 (6 hours of exposure), none of the alloys exhibited intergranular corrosion and for all the average depth of attack was less than 45 microns.
- ASTM G44 the LT oriented specimens tested at 75% of tensile yield strength, all alloys passed more than 40 days in test.
- the alloys have an S-phase solvus temperature in the range of 797-845°F, and an M-phase solvus temperature in the range of 743-785°F, and have no T-phase.
- the ingots were homogenized and then hot rolled to 4.06 mm (0.160 inch) and then cold rolled to a final gauge of 2.03 mm (0.80 inch). (No samples were annealed.) The final gauge samples were then solution heat treated, then cold water quenched, and then naturally aged for about 5 days. The naturally aged samples were then two-step artificially aged by first aging at 121.1°C (250°F) for 8 hours and then aging at 160°C (320°F) for 4 hours. After cooling to room temperature, the alloys were then given a simulated paint bake of 365°F (185°C).
- alloys 17-21 and 23 contain about the same amount of manganese and zirconium as that of Alloy E of Example 1.
- the ingot cast alloys realize about 70-80 MPa higher strength at about equivalent three-point bend extension relative to the continuous cast alloys.
- the ingot cast alloys also realize about 2.5-2.6 higher three-point bend extension at about equivalent strength.
- the alloys have an S-phase solvus temperature in the range of 792-846°F, an M-phase solvus temperature in the range of 715-780°F, and have no T-phase.
- Alloy 18 has the highest S-phase solvus temperatures and the poorest bend performance.
- Alloy 20 is similar to Alloy E of Example 1 and has a solvus temperature below 800°F. Lower S-phase solvus temperatures may facilitate improved properties due to, for instance, improved quench insensitivity properties.
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US20230250516A1 (en) | 2023-08-10 |
JP2023545854A (en) | 2023-10-31 |
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