Metallurgical product and structure member for aircraft made of Al-Zn-Cu-Mg alloy

a technology of al-zn-cu-mg alloy and metallurgical products, which is applied in the field of structural members, can solve the problems that certain required properties are difficult to optimize at the same time independently of each other

Inactive Publication Date: 2005-07-14
ALCAN RHENALU +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0015] Another purpose was to obtain aircraft structural members, and particularly members for the under surface wings of aircraft, or for machining integral structures made of Al—Zn—Cu—Mg alloy, with a better compromise between mechanical strength, toughness and fatigue strength properties, than is possible to achieve with prior materials.

Problems solved by technology

It is generally known that when manufacturing semi-finished products and structural members for aeronautical construction, certain various required properties are difficult to optimize at the same time independently of each other.
Some frequently employed properties such as fatigue strength, corrosion resistance, formability and elongation at failure are related to these mechanical properties (or “characteristics”) in a complicated and frequently unpredictable manner.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0054] An alloy N was made for which the chemical composition complies with the invention. The liquid metal was treated firstly in a holding furnace by injecting gas using an IRMA® type of rotor, and then in an Alpur® type of ladle, these two trademarks belonging to the inventors. Refining was done in line, in other words in the channel between the holding furnace and the Alpur® ladle, with 1.1 kg / tonne of Al-3% Ti-0.15% C wire (9.5 mm diameter). An industrial sized rolling ingot was cast. It was relaxed for 10 h at 350° C.

[0055] The product thus cast was homogenised after scalping for 15 hours at a temperature between 471° C. and 482° C. (between 880° F. and 900° F.) and then hot rolled to a thickness of 5 mm (0.2 inches). The rolling start temperature was 450° C. (840° F.) and the rolling end temperature was 349° C. (660° F.). Plates with width 178 mm (7 inches) and length 508 mm (20 inches) were sampled. These coupons were solution heat treated in a salt bath furnace for 1 hour ...

example 2

[0073] An alloy M with chemical composition complying with the invention was produced.

[0074] For comparison, a plate made of 2324 alloy according to prior art (reference 1) was produced according to a conventional casting process.

[0075] The chemical compositions of alloys M and I measured on a spectrometry slug taken from the casting runner, are given in the following table:

TABLE 5Chemical compositionAlloySiFeCuMnMgZnZrM0.050.062.05—1.647.080.08I (AA2324)3.8-4.40.3-0.91.2-1.8

[0076] After scalping, rolling ingots made of alloy M were homogenised for 15 hours at 479° C., and then slowly cooled to 420-440° C. and rolled to a thickness of 25.4 mm. The outlet temperature from the hot rolling mill was 354° C., which is significantly lower than the value normally used for this type of product.

[0077] The plates thus obtained were then subjected to a solution heat treatment at 479° C. for 4 hours (total time, about ⅓ of which is spent in the temperature increase), and were then quenched...

example 3

[0093] An alloy P similar to alloy M in example 2 was produced. A manufacturing procedure similar to that for example 2 was used to make thick integrally hot rolled plates from this alloy (input temperature 420-440° C.), with a thickness of 75 mm.

[0094] After solution heat treatment and quenching as indicated in example 2, the plates were subjected to annealing processes with the following two steps: [0095] First step: temperature increase at 30° C. / hour up to 120° C. and hold for 6 hours at this temperature of 120° C. [0096] Second step: temperature increase at 15° C. / hour up to 160° C. and hold for 5 hours (process A), 10 hours (process B) or 15 hours (process C) at this temperature of 160° C.

[0097] The values of Kapp(LT) were determined on type C(T) test pieces with W=127 mm and B=7.6 mm.

[0098] Table 10 summarises the main mechanical characteristics obtained:

TABLE 10RP0.2(L)Rm(L)A(L)KIC(L-T)Kapp(L-T)Process[MPa][MPa][%][MPa{square root}m][MPa{square root}m]A5425619.730.157.1...

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Abstract

The present invention relates to a work-hardened product, and particularly a rolled, extruded and/or forged product made of an alloy with composition (% by weight): Zn 6.7-7.3% Cu 1.9-2.5% Mg 1.0-2.0% Zr 0.04-0.15% Fe ≦0.15 Si ≦0.15 other elements ≦0.05 each and ≦0.15 total, remainder aluminium and wherein Mg/Cu<1. The product is preferable treated by solution heat treatment, quenching, cold working and artificial aging. Cold working may be achieved by controlled tension and/or cold transformation, for example rolling or drawing. The product may be used, for example, as an aircraft structural member.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application claims priority to U.S. Ser. No. 60 / 529,594 filed Dec. 16, 2003, the content of which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to rolled, extruded and / or forged products made of Al—Zn—Cu—Mg alloy treated by solution heat treatment, quenching, cold working and artificial aging, and particularly structural members made from such products and designed for use such as in aircraft construction. [0004] 2. Description of Related Art [0005] It is generally known that when manufacturing semi-finished products and structural members for aeronautical construction, certain various required properties are difficult to optimize at the same time independently of each other. When the chemical composition of the alloy or the parameters of production processes are modified, several critical mechanical properties c...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22C21/10C22F1/053
CPCC22F1/053C22C21/10
Inventor BES, BERNARDDANGERFIELD, VICDUMONT, DAVIDEHRSTROM, JEAN-CHRISTOPHEWARNER, TIMOTHY
Owner ALCAN RHENALU
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