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AlCuMg ALLOYS WITH HIGH DAMAGE TOLERANCE SUITABLE FOR USE AS STRUCTURAL MEMBERS IN AIRCRAFTS

a technology of aluminum alloys and damage tolerance, applied in the field of damage tolerance aluminum alloys, can solve the problems of unusual (hot cross rolling) or otherwise expensive manufacturing steps

Inactive Publication Date: 2007-12-13
ALCAN RHENALU
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a manganese-free aluminum alloy that has good fracture toughness and mechanical strength, making it suitable for use in applications that require high damage tolerance. The alloy has a low amount of Mn, which is replaced by zirconium or zirconium plus scandium. The alloy can be produced as a plate or sheet, with various combinations of properties such as high tensile yield strength and elongation at fracture. The invention also provides methods for manufacturing the sheet and plate products in the manganese-free alloy.

Problems solved by technology

These methods involve unusual (hot cross rolling) or otherwise expensive manufacturing steps (repeated intermediate heat treatment) in order to obtain a precisely controlled microstructure.

Method used

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  • AlCuMg ALLOYS WITH HIGH DAMAGE TOLERANCE SUITABLE FOR USE AS STRUCTURAL MEMBERS IN AIRCRAFTS
  • AlCuMg ALLOYS WITH HIGH DAMAGE TOLERANCE SUITABLE FOR USE AS STRUCTURAL MEMBERS IN AIRCRAFTS
  • AlCuMg ALLOYS WITH HIGH DAMAGE TOLERANCE SUITABLE FOR USE AS STRUCTURAL MEMBERS IN AIRCRAFTS

Examples

Experimental program
Comparison scheme
Effect test

example 1

Manufacturing and Microstructural Characterization

A) Manufacturing of Alloys / Tempers

[0081] Casting of several ingots was conducted at a laboratory scale cast house, on (320 mm×120 mm) slabs (2t casting unit). The compositions in weight % are given in Table 1.

TABLE 1Composition of the alloys (in weight %)AlloySiFeCuMnMgTiZrScDT0.064.120.401.370.022DT + Zr0.063.810.0081.410.0220.109DT + Zr + Sc0.073.810.0081.360.0240.1070.02824LoMn0.054.200.241.230.0160.110.03224HiMn0.064.140.511.240.0190.110.032

[0082] Table 1 also gives the alloy designations that will be used hereinbelow: [0083]−DT stands for reference high damage tolerance 2024 (AA2024A) [0084]−DT+ZR and DT+Zr+Sc respectively designate DT with manganese totally replaced by zirconium and zirconium+scandium. [0085] 24LoMn and 24HiMn stand for DT (AA2024A) based compositions with Zr+Sc and various (respectively 0.25% and 0.50%) Mn levels.

[0086] The detailed conditions of the transformation of the slabs are provided below: [0087]...

example 2

Mechanical and Corrosion Evaluation IN T3X Tempers

[0096] The alloys manufactured in Example 1 in the various T3X tempers were characterized as follows: [0097] Static Tensile Testing at half-thickness in the L and LT directions [0098] Exfoliation corrosion resistance [0099] Damage tolerance: [0100] Plane stress fracture toughness at half-thickness by Kapp determination on 6.35 mm (0.25″) thick specimens with W=40 mm (1.6″) in the L-T orientation (according to ASTM E561). [0101] Fatigue crack growth rate (FCGR) at half-thickness on 6.35 mm (0.25″) thick “CT” specimens with W=40 mm (1.6″) in the L-T and T-L orientation (according to ASTM E647).

[0102] The static tensile properties in the T3X tempers are summarized in Table 4 and FIGS. 2 and 3.

[0103] The following effects are demonstrated: [0104] A Zr+Sc addition totally compensates for manganese (compare DT and DT+Zr+Sc). [0105] Manganese is clearly beneficial for UTS and TYS tensile properties (compare DT+Zr+Sc”, “24LoMn”, “24HiMn”....

example 3

Mechanical and Corrosion Evaluation in T8X Tempers

[0120] The alloys manufactured in Example 1 (various T3X tempers) were artificially aged to T8X tempers as explained in Example 1.

[0121] The high manganese variant named 24HiMn was not selected for the T78X evaluation, due to its relatively poor toughness.

[0122] Prior to the artificial aging treatment, aging kinetics (using Vickers hardness as a strength indicator) have been conducted on the various alloys in different T3X conditions. The results are provided in FIGS. 9 and 10.

[0123] On some of the cases (apparently independent of alloy chemistry and T3X temper), an initial decrease of hardness is observed for low ageing times; this is probably due to retrogression phenomena. Then, hardness increases, owing to precipitation hardening. A peak in hardness is generally observed, before hardness slowly decreases by over-ageing.

[0124] Table 8 below gives the aging treatment duration chosen for the complete characterization program in...

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Abstract

New alloys for potential use in applications such as in lower wing skins and fuselage skins are disclosed. Specifically, Mn-free 2×24 alloys potentially suitable for thick plate and thin plate and sheet applications are believed to be novel and to provide unexpectedly superior properties.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of U.S. application Ser. No. 10 / 614,888, filed Jul. 9, 2003, which claims priority from Provisional Application Ser. No. 60 / 394,234, filed Jul. 9, 2002, 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 damage tolerant aluminum alloys, and in particular, to such alloys useful in the aerospace industry suitable for use in lower wing skin applications and as fuselage skin. [0004] 2. Description of the Related Art [0005] Materials particularly adapted for use in lower wing skin applications including 2×24 alloys are generally known, as described, for example, in U.S. Pat. Nos. 5,213,639 and 6,444,058, as well as in the PCT application WO 99 / 31287, the content of which is incorporated herein by reference in their entireties. Damage tolerance of 2×24 alloys is of particular imp...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B22D21/00B22D25/06C22F1/057C22C21/12C22C21/16C22F1/053
CPCC22C21/16C22F1/057C22F1/053
Inventor DIF, RONANWARNER, TIMOTHYBERNARD, BES
Owner ALCAN RHENALU