High-strength alloy based on aluminium and a product made of...

Details High-strength alloy based on aluminium and a product made of... High-strength alloy based on aluminium and a product made of...

2003-06-25

2004-09-14

King, Roy (Department: 1742)

Alloys or metallic compositions

Aluminum base

Copper containing

C420S535000, C148S417000

Reexamination Certificate

active

06790407

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to non-ferrous metallurgy, and in particular it relates to high strength alloys of Al—Zn—Mg—Cu system used as a structural material for main parts in aircraft (upper skins and stringers of the wing, loaded beams, etc), in rocket-, transportation and instrument engineering.
BACKGROUND OF THE INVENTION
Well-known are high strength aluminium-based alloys of Al—Zn—Mg—Cu system additionally doped with a minor amount of zirconium.
The Russian alloy 1973 has the following composition (in weight %):
zinc
5.6-6.5
magnesium
2.0-2.6
copper
1.4-2.0
zirconium
0.08-0.16
titanium
0.02-0.07
manganese
≦0.10
chrome
≦0.05
iron
≦0.15
silicon
≦0.10
aluminium -
balance [1]
The American alloy 7050 comprises (wt %):
zinc
5.7-6.7
magnesium
1.9-2.6
copper
2.0-2.6
zirconium
0.08-0.15
titanium
≦0.06
manganese
≦0.10
chrome
≦0.04
iron
≦0.15
silicon
≦0.12
aluminium -
balance [2]
Also is patented the American alloy comprising (wt %):
zinc
5.9-6.9
magnesium
2.0-2.7
copper
1.9-2.5
zirconium
0.08-0.15
titanium
≦0.06
chrome
≦0.04
iron
≦0.15
silicon
≦0.12
aluminium -
balance [3]
The common disadvantage of all said alloys is the unsatisfactory level of static strength and specific characteristics which doesn't allow to improve service properties, to increase the weight efficiency of the articles aiming to raise carrying capacity, to save fuel, to increase flight distance range, etc.
The American alloy is suggested comprising (wt %):
zinc
7.6-8.4
magnesium
1.8-2.2
copper
2.1-2.6
zirconium
0.03-0.30
manganese
 0.1-0.35
iron
0.03-0.1 
silicon
0.03-0.1 
and at least one element from the group including
halfnium
0.03-0.4 
vanadium
0.05-0.15
aluminium -
balance [4]
Said alloy has the following disadvantages:
high and superhigh strength is mainly achieved by heavy alloying with main elements—zinc, magnesium, copper (their maximum sum >13.0%), but the increased amount of copper leads to the reduction of ductility, crack—and fatigue resistance;
the additional alloying with expensive elements (hafnium, vanadium) is used, and that leads to the increase in cost of semi-finished products and finished articles, especially when there is a large-scale production and the products are of large sizes;
the alloy has the unsatisfactory ductility in as-cast condition (and therefore has the tendency to appearing of cracks in ingots especially large-sized ingots which are cast from such alloys with difficulty) and under the deformation of semiproducts;
the alloy's composition doesn't provide the optimum conditions of the microstructure formation and service characteristics of such members as skins and stringers of the wing which are needed for modem and future aircraft.


REFERENCES:
patent: 4305763 (1981-12-01), Quist et al.
patent: 5221337 (1993-06-01), Luers et al.
patent: 48031807 (1973-10-01), None
patent: 61186445 (1986-08-01), None
patent: 2107739 (1990-04-01), None
patent: 4263035 (1992-09-01), None
patent: 436876 (1974-12-01), None
RF Society “Knowledge”; Moscow House of Science & Technology Popularization Named After Dzerzhinsky; New Non-Ferrous Alloys; Seminar Proceedings; Moscow; 1990; p. 33.
Aluminum Standards and Data 1998 Metric Si; Third Edition Apr. 1998; The Aluminum Association Incorporated; p. 6-6.

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