US2024175114A1PendingUtilityA1
Methods of producing 2xxx aluminum alloys
Est. expiryAug 24, 2041(~15.1 yrs left)· nominal 20-yr term from priority
C22F 1/057C22C 21/14C22C 21/16C22C 21/18C22C 21/12
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Claims
Abstract
Methods of making new 2xxx aluminum alloy sheet products are disclosed. In one approach, a method comprises artificially aging a 2xxx aluminum alloy in at least two-steps. In one embodiment, the first aging step comprises first aging a 2xxx aluminum alloy at a first temperature of from 300° F. to 450ºF and for a first aging time of from 4 to 120 hours, and second aging the 2xxx aluminum alloy at a second temperature for a second aging time of from 30 minutes to 120 hours, wherein the second temperature is from 20° F. to 150° F. lower than the first temperature. The new two-step artificial aging step may facilitate an improved combination of properties, such as an improved combination of two or more of strength, ductility, fracture toughness, and corrosion resistance.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . A method comprising:
(a) first aging a 2xxx aluminum alloy at a first temperature of from 300° F. to 450° F. and for a first aging time of from 4 to 120 hours; (b) second aging the 2xxx aluminum alloy at a second temperature for a second aging time of from 30 minutes to 120 hours, wherein the second temperature is from 20° F. to 150° F. lower than the first temperature; wherein 2xxx aluminum alloy comprises less than 0.05 wt. % Li; wherein, at least partially due to the first aging and second aging steps, the 2xxx aluminum alloy is (i) LT stress corrosion cracking resistant, (ii) ST stress corrosion cracking resistant, or (iii) both LT stress corrosion cracking resistant and ST stress corrosion cracking resistant.
2 . The method of claim 1 , wherein the first temperature is from 330° F. to 370° F. and the first time is from 12 to 36 hours.
3 . The method of claim 2 , wherein the second aging temperature is from 250° to 290° F., and wherein the second aging time is from 12 to 36 hours.
4 . The method of claim 1 , wherein the first aging time is t 1 actual , wherein t 1 actual is determined according to an equivalent time at 350° F. in accordance with the below formula:
t
1
350
°
F
.
eq
.
=
t
1
actual
*
exp
(
-
156000
8.314
*
(
1
5
9
(
T
1
°
F
.
-
32
)
+
273
-
1
5
9
(
318
)
+
273
)
)
wherein (a) T 1 ° F. is the first temperature of the first aging step in Fahrenheit, wherein T 1 ° F. is from 300 to 450° F., (b) t 1 actual is from 10 to 120 hours, and (c) t 1 350° F. eq. is the equivalent amount of time at a first step temperature of 350° F.
5 . The method of claim 4 , wherein t 1 350° F. eq. is from 20 to 30 hours.
6 . The method of claim 1 , comprising:
after the first aging step, cooling the 2xxx aluminum alloy to room temperature; and reheating the 2xxx aluminum alloy from room temperature to the second temperature of the second aging step.
7 . The method of claim 1 , comprising:
after the first aging step, cooling the 2xxx aluminum alloy to the second temperature of the second aging step.
8 . The method of claim 1 , comprising:
preparing a wrought 2xxx aluminum alloy for solution heat treating; and then solution heat treating and then quenching the wrought 2xxx aluminum alloy; and then completing the first aging step and the second aging step.
9 . The method of claim 8 , wherein the preparing comprising:
casting the 2xxx aluminum alloy as in ingot or billet; working the ingot or billet to the final gauge product, wherein the working comprises hot working.
10 . The method of claim 9 , wherein the working further comprises cold working.
11 . The method of claim 1 , wherein the LT stress corrosion cracking resistance is two-out-of-three specimens of the 2xxx aluminum alloy do not fail after 60 days of alternate immersion testing at a net stress of 300 MPa in the LT direction and in accordance with ASTM G47 using constant-strain type stressing frame fixtures according to FIG. 4 of ASTM G49.
12 . The method of claim 11 , wherein all three specimens do not fail after 60 days of alternate immersion testing at a net stress of 300 MPa in the LT direction.
13 . The method of claim 1 , wherein the ST stress corrosion cracking resistance is two-out-of-three specimens of the 2xxx aluminum alloy do not fail after 60 days of alternate immersion testing at a net stress of 250 MPa in the ST direction and in accordance with ASTM G47 using constant-strain type stressing frame fixtures according to FIG. 4 of ASTM G49.
14 . The method of claim 13 , wherein all three specimens do not fail after 60 days of alternate immersion testing at a net stress of 250 MPa in the ST direction.
15 . The method of claim 1 , wherein the 2xxx aluminum alloy comprises from 0.08 to 0.20 wt. % Ti, from 4.5 to 5.5 wt. % Cu, from 0.20 to 0.6 wt. % Mn, from 0.20 to 0.8 wt. % Mg, from 0.05 to 0.60 wt. % Ag, up to 1.0 wt. % Zn, up to 0.30 wt. % Fe, up to 0.20 wt. % Si, up to 0.25 wt. % Zr, up to 0.25 wt. % Cr, and up to 0.25 wt. % V, the balance being aluminum, incidental elements and impurities.
16 . The method of claim 15 , wherein the 2xxx aluminum alloy is a 2x39 alloy modified to include 0.08 to 0.20 wt. % Ti.
17 . A wrought 2xxx aluminum alloy product comprising:
from 0.08 to 0.20 wt. % Ti, from 4.5 to 5.5 wt. % Cu; from 0.20 to 0.6 wt. % Mn; from 0.20 to 0.8 wt. % Mg; from 0.05 to 0.60 wt. % Ag; up to 1.0 wt. % Zn; up to 0.30 wt. % Fe; up to 0.20 wt. % Si; up to 0.25 wt. % Zr; up to 0.25 wt. % Cr; up to 0.25 wt. % V; and less than 0.05 wt. % Li; the balance being aluminum, incidental elements and impurities; wherein the wrought 2xxx aluminum alloy has a cross-sectional thickness of from 12.7 mm to 152 mm; wherein the 2xxx aluminum alloy is (i) LT stress corrosion cracking resistant, (ii) ST stress corrosion cracking resistant, or (iii) both LT stress corrosion cracking resistant and ST stress corrosion cracking resistant.
18 . The wrought 2xxx aluminum alloy of claim 17 , wherein the wrought 2xxx aluminum alloy realizes a T8 temper tensile yield strength (LT) of at least 390 MPa.
19 . The wrought 2xxx aluminum alloy of claim 18 , wherein the wrought 2xxx aluminum alloy realizes a T8 temper plane-strain (K IC ) fracture toughness (T-L) of at least 30 MPa-sqrt-m.
20 . The wrought 2xxx aluminum alloy of claim 19 , wherein the wrought 2xxx aluminum alloy realizes an elongation (LT) of at least 6.0%.Join the waitlist — get patent alerts
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