US2019249285A1PendingUtilityA1
Thin sheets made of an aluminum-magnesium-scandium alloy for aerospace applications
Est. expiryOct 17, 2036(~10.3 yrs left)· nominal 20-yr term from priority
C22C 21/06C22F 1/047
64
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Claims
Abstract
The invention relates to a method for producing a wrought product made of an aluminum alloy composed, in wt %, of Mg: 3.8-4.2; Mn: 0.3-0.8 and preferably 0.5-0.7; Sc: 0.1-0.3; Zn: 0.1-0.4; Ti: 0.01-0.05; Zr: 0.07-0.15; Cr: <0.01; Fe: <0.15; Si<0.1; wherein the homogenization is carried out at a temperature of between 370° C. and 450° C., for between 2 and 50 hours, such that the equivalent time at 400° C. is between 5 and 100 hours, and the hot deformation is carried out at an initial temperature of between 350° C. and 450° C. The invention also relates to hot-worked products obtained by the method according to the invention, in particular sheets with a thickness of less than 12 mm. The products according to the invention are advantageous as they offer a better compromise in terms of mechanical strength, toughness and hot-formability.
Claims
exact text as granted — not AI-modified1 . Method for producing a wrought product made of an aluminum alloy comprising:
a) Producing a molten metal bath having an aluminum base, comprising, in wt %,
Mg: 3.8-4.2;
Mn: 0.3-0.8 and optionally 0.5-0.7;
Sc: 0.1-0.3;
Zn: 0.1-0.4;
Ti: 0.01-0.05 and optionally 0.015-0.030;
Zr: 0.07-0.15 and optionally 0.08-0.12;
Cr: <0.01;
Fe: <0.15;
Si<0.1;
other elements <0.05 each and <0.15 combined, the remainder being aluminum;
b) Casting an unwrought product from said metal bath; c) Homogenizing said unwrought product at a temperature that lies in the range 370° C. to 450° C., for a duration that lies in the range 2 to 50 hours such that the equivalent time at 400° C. lies in a range 5 to 100 hours,
the equivalent time t(eq) at 400° C. being defined by formula:
t
(
eq
)
=
∫
exp
(
-
29122
/
T
)
dt
exp
(
-
29122
/
T
ref
)
where T is the current temperature expressed in Kelvin, which changes over time t (in hours) and Tref is a reference temperature of 400° C. (673 K), t(eq) being expressed in hours, the constant Q/R=29122 K being derived from the activation energy for the diffusion of Zr, Q=242000 J/mol,
d) Hot-working the unwrought product thus homogenized is hot worked with an initial temperature in the range 350° C. to 450° C. and is optionally cold-worked;
e) a flattening and/or straightening process is optionally carried out;
f) an annealing process is optionally carried out at a temperature that lies in the range 300° C. to 350° C.
2 . Method according to claim 1 , wherein the homogenization duration lies in a range 5 to 30 hours.
3 . Method according to claim 1 , wherein working is carried out by rolling in order to obtain a sheet metal and wherein a final thickness of a sheet obtained is less than 12 mm.
4 . Method according to claim 1 , wherein working is carried out by extrusion in order to obtain a profile.
5 . Wrought product made of an aluminum alloy having the composition, in wt %,
Mg: 3.8-4.2; Mn: 0.3-0.8 and optionally 0.5-0.7; Sc: 0.1-0.3; Zn: 0.1-0.4; Ti: 0.01-0.05 and optionally 0.015-0.030; Zr: 0.07-0.15 and optionally 0.08-0.12; Cr: <0.01; Fe: <0.15; Si<0.1; other elements <0.05 each and <0.15 combined, the remainder being aluminum, obtainable by the method according to claim 1 .
6 . Wrought product in the form of a sheet having a thickness of less than 12 mm, obtainable by the method according to claim 3 , wherein
(a) the tensile yield stress thereof measured at 0.2% elongation in the LT direction of at least 250 MPa, and optionally of at least 260 MPa and/or (b) the tensile yield stress thereof measured at 0.2% elongation in the L direction of at least 260 MPa, and optionally of at least 270 MPa.
7 . Wrought Product in the form of a Sheet according to claim 6 , wherein
(c) the toughness K R 60 thereof, measured on specimens of type CCT760 in the L-T direction (where 2ao=253 mm), for an effective crack growth Δa eff of 60 mm, of at least 155 MPa √{square root over (m)} , and optionally of at least 165 MPa √{square root over (m)} and/or (d) the toughness K R 60 thereof, measured on specimens of type CCT760 in the T-L direction (where 2ao=253 mm), for an effective crack growth Δa eff of 60 mm, of at least 160 MPa √{square root over (m)} , and optionally of at least 170 MPa √{square root over (m)} .
8 . Method according to claim 1 , wherein, at the end of f, forming is carried out at a temperature that lies in the range 300° C. to 350° C.
9 . Aircraft fuselage element obtainable according to the method according to claim 8 , wherein
(a) the tensile yield stress thereof measured at 0.2% elongation in the LT direction of at least 250 MPa, and optionally of at least 260 MPa and/or (b) the tensile yield stress thereof measured at 0.2% elongation in the L direction of at least 260 MPa, and optionally of at least 270 MPa.Cited by (0)
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