PT2006403E - Aluminium-based alloy - Google Patents

Abstract

The invention covers a field of metallurgy of alloys based on aluminum, in particular, to the alloy of aluminum-copper-magnesium-lithium system applied for manufacturing semi-finished products and parts thereof used as structural materials for aerospace engineering. The invention is directed to enhancement of ductility and processibility of aluminum-copper-magnesium-lithium system alloys, increase of yields by manufacturing semi-finished products and parts thereof, assurance of possibility to produce thin sheets, thin-walled sections and die-forgings by reducing production labor intensiveness, by preservation required strength and operation characteristics demanded to structural materials for aerospace engineering. The indicated technical result is achieved by the fact, that the alloy contains the following component ratio, wt %: lithium- 1.6 - 1.9; copper- 1.3 - 1.5; magnesium- 0.7 - 1.1; zirconium- 0.04 - 0.2; beryllium- 0.02 - 0.2; titanium- 0.01 - 0.1; nickel-0.01-0.15; manganese- 0.01 - 0.2; gallium- O 0.001; - 0.01 - 0.3; sodium- up to 0.0005; calcium- 0.005 - 0.02; and, at least, one element selected from the group including vanadium- 0.005 - 0.01 and scandium-0.005 - 0.01; aluminum- remainder.

Description

DESCRIPTION

ALUMINUM-BASED ALLOYS

An invention discloses the field of aluminum-based alloys metallurgy, in particular the aluminum-copper-magnesium-lithium system alloy applied to the manufacture of semi-finished products and their parts used as structural materials for aerospace engineering.

It is known that lithium aluminum alloys have a unique combination of mechanical properties, namely of low density, increased modulus of elasticity, and sufficiently strong force characteristics. The availability of the indicated properties allows to use the alloys of this system as structural material for aerospace engineering, which allows to improve a number of aircraft performance characteristics, in particular air vehicle, vehicle weight reduction, fuel economy, increased load capacity.

However, lithium-aluminum alloys have a disadvantage - low ductility at conditions close to the maximum force (NI Fridlyander, KV Chuistov, AL Berezina, NI Kolobnev, Alloys-lithium alloys. , page 177).

State of the art

Aluminum alloy is known to have weight% Titanium 1.7 - 2.0 Copper 1.6 - 2.0 Magnesium 0.7 - 1.1 Zirconium 0.04 - 0.16 Beryllium 0.02 - 0.2 Titanium 0.01 - 0.07 Nickel 0.02 - 0.15 1

Manganese 0.01 0.4

Aluminum

Remainder (USSR Inventor Certificate No. 1767916, IPC C 22 C 21/16, date of publication 1997.08.20)

The drawbacks of said alloy are its low processability, high laborability, and low yield when manufacturing semi-finished products and their parts, the impossibility of obtaining thin sheets, thin-walled and matrix-fused sections therein.

The reasons which cause the abovementioned disadvantages to occur when using the known alloy include the fact that the relatively high content of copper in the known alloy negatively influences cracking at high temperatures and ductility in the formation, which leads to increased fissure , high bending and non-flat bending in finishing operations, namely smoothing and stretching of semi-finished products. Aluminum alloy is known - 8093 (alloy designation conforms to alloy numbers and according to the definitions registered by the Aluminum Association, Washington, USA) having weight%: Lithium 1.9 - 2.6 Copper 1.0 - 1.6 Magnesium 0.9 - 1.6 Zirconium 0.04 - 0. Titanium up to 0.1 Manganese up to 0.1 Zinc up to 0.25 Aluminum Remaining (International designation of alloys and chemical composition limits of cast aluminum and aluminum alloys, Aluminum Association: 2004, pages 12, 13) . 2

The disadvantages of the alloy indicated are the increased costs of the alloy, its low processability, high labor-intensive workability and low yield in the manufacture of semi-finished products and their parts, impossibility in obtaining thin sheets, thin-walled sections and matrix in it.

The reasons which cause the above disadvantages to occur when using the known alloy include the fact that the known alloy has an increased lithium content, in addition, the increased lithium content has led to the formation of force phases slightly increasing the characteristics of strength of the alloy, but at the same time considerably reduces its ductility to the molding and forming leading to increased cracking, high bending and non-flat bending in the finishing operations, namely smoothing and drawing of the semi-finished products. The alloy closest to the chemical composition and function of the claimed aluminum based alloy is the alloy having wt%

Lithium 1.7 - 2.0 Copper 1.6 - 2.0 Magnesium 0.7 - 1.1 Zirconium 0.04 - 0.2 Beryllium 0.02 - 0.2 Titanium 0.01 - 0.1 Nickel 0.01 - 0.15 Manganese 0.001 - 0.05 Gallium 0.001 - 0.05 Zinc 0.01 - 0.3 Sodium 0.0005 - 0.0 Remaining Aluminum (Patent of the Federation Russian Patent No. 2180928, IPC 7 C 22 C 21/00, C 22 C 21/16, publication date 2002.03.27, see also EP-A-1 788 101). 3

The disadvantages of the indicated alloy taken for a prototype are its relatively low processability, high labor-intensive workability, and low yield in the manufacture of semi-finished products and their parts, impossibility in obtaining thin sheets, thin-walled sections and melted by matrix in it.

The reasons which cause the occurrence of the disadvantages mentioned above when using the known alloy taken for a prototype refer to the fact that the known alloy is characterized by the increased copper content which negatively influences the cracking at high temperatures and the ductility in the formation leading to increased fissure, high bending and non-flat bending in the finishing operations, namely smoothing and stretching of the semi-finished products, and the increased sodium and gallium content leads to a considerable increase in cracking to (AV Kurdvumov, SV Inkin, VS Chulkov, GG Shadrin, Metallurgical Admixtures in Aluminum Alloys, M.: Metallurgy, 1988, pages 90, 99) which considerably complicates a the purpose of obtaining acceptable ingots and in addition to receiving semi-finished products of various types of shape, and also to the quality coating on the semi-finished products rolled as a result of the formation of substantial areas of non-welded coating on their surfaces.

DISCLOSURE OF THE INVENTION The object which the invention proposes to solve is the development of an aluminum-based alloy for the manufacture of semi-finished products and parts thereof for aerospace engineering, without the disadvantages listed above and inherent in known solutions of engineering. A technical result obtained by an embodiment of an invention comprises obtaining an alloy having increased ductility, which allows improving its processability, to increase yields in the manufacture of semi-finished products and their parts, which ensures the possibility of producing thin sections, thin-walled and die-cast sections by reducing the production of the work intensity, while retaining the required strength and operating characteristics of the alloy, as well as semi-finished products and their parts required by structural materials for aerospace engineering. The object of the present invention is solved by the known aluminum-based alloy containing lithium, copper, magnesium, zirconium, beryllium, titanium, nickel, manganese, gallium, zinc, sodium, additionally contains calcium and at least one element selected from a group including vanadium and scandium having the following proportion of components, wt%: Lithium 1.6 - Oh I-1 Copper 1.3 - 1.5 Magnesium 0.7 - 1.1 Zirconium 0.04 - 0.2 Beryllium 0.02 - 0.2 Titanium 0.01 - 0.1 Nickel 0.1 - 0.15 Manganese 1-1o - 0.2 Gallium up to .001 Zinc 0.01 - 0.3 Sodium up to 0. 0005 Calcium 0.005 - 0.

At least one element selected from a group including:

Vanadium Scandium Aluminum 0.005 - 0.01 0.005 - 0.01 Remainder Aluminum alloy used for the manufacture of semi-finished products and parts differs from the prior art either quantitatively (reduced copper, gallium, and sodium content) or qualitatively (in addition contains calcium, and at least one element selected from a group including vanadium and scandium). 5

We have determined that the increased copper content results in the formation of irregularly shaped intermetallic pore compounds, with copper-containing phases formed by the crystallization of the alloy in areas with increased copper content within the grains and at their limits. These phases are represented not by separate particles but by extensive accumulations preventing deformation in the cut in the forming process which results in a considerable reduction of the alloy's ductility. Reduction of the copper content in the alloy to the limits of 1.3 - 1.5% by weight practically allows the total transfer to the solid solution which results in a considerable reduction of the inclusion of the volume ratio of the intermetallic compounds of phases containing pores as determined by the electron of the alloy, and, consequently, to enable alloy ductility. Reduction of the copper content of less than 1.3% by weight will not have a permissible influence on the ductility characteristics of the alloy but will considerably reduce its strength characteristics.

In addition, we determined that gallium and sodium do not form phases with aluminum and accumulate at grain boundaries resulting in a brittle fracture along the grain boundary in the processes of crystallization of the alloy and its shape.

We determined that with gallium and sodium contents of less than 0.001 and 0.0005% by weight respectively, they practice and fully dissolve in the solid solution resulting from the allowability of the alloy ductility. Calcium in the amount of 0.005-0.02% by weight is an additive that binds excess sodium and other residual elements of the alloy resulting in the formation of rounded compounds of isolated intermetallic and their coagulation resulting in more favorable conditions of cut deformation , and, consequently, in the permissibility of the alloy process ductility. The introduction of one or more vanadium scandium group elements in the indicated amounts facilitates the formation of a homogeneous fine grain structure which promotes the enhancement of the zirconium role as a modifying agent which ensures the structural strength of the semi-finished products and parts of the alloy, which allows to obtain the required level of alloy strength properties. 6

From the proposed aluminum based alloy it is possible to manufacture several semi-finished products: sheets and plates, die-cast, extruded. Of the semi-finished products of the proposed alloy it is possible to obtain various parts, for example, panels for coating aircraft fuselage structures, protective structure elements, welded fuel tanks, and other aerospace engineering elements.

Exemplary embodiments of the invention

Under industrial conditions a flat ingot with a cross-section of 300 x 1,100 mm and round ingots with diameters of 190 mm and 350 mm were cast in each of the alloys whose chemical composition is given in Table 1. Alloy No. 1 corresponds to the alloy taken as a prototype, the leagues n ° s. 2, 3, 4 correspond to those proposed. The melt degassing and ingot molding of the filler was done at the temperature of 170-730 ° C.

Example 1

Later, the composite sheets were fabricated from the flat ingots in each of the alloys. The sheets were fabricated on the basis of a flow process by rolling at a temperature of from 430øC to 6.5 mm in thickness with coil winding, and thereafter, after the temperature of 400øC, by cold rolling.

It should be mentioned that it was possible to laminate a sheet in alloy no. 1 only up to 0.9 mm thick and the continuation of the rolling was stopped due to the presence of cracks of 30 mm depth in the edges of the sheets and the presence of 2 ruptures in the coil.

The sheets in the alloys n. 2, 3, 4 were laminated without ruptures up to 0.5 mm thick.

The following finishing operations, smoothing and stretching sheets in alloys No. 2, 3, 4 in comparison with alloy No. 1 and despite their low thickness, were made more successfully and with fewer inspection of deficiencies, folds, not flat and cracks. 7

AI Remainder CD ON Sc o o 1 o o o r-> 1 ooo 1 oo Ca, .005 .02 το * ooor- PO 1-1 CNJ O ooo o ooos O ooo oo oo oo oo oo oo o oo ooor- ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo EH •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• " I ood LO PO oi-1 r-1 r-1 <S \ CTi co co-1 r-1 i-1 i-1 Oligomposition of the alloy 0 G * -1 CM ΓΟ CJ u 0 Çu o T5 The yield per sheets of sheets in the alloys ## STR5 ## wherein R 1 is as defined in claim 1; 2, 3, 4 were greater than 30% than in alloy # 1.

Later, the samples of the leaves in the alloys 1, 2, 3, 4 were tested in static tension with determination of the tensile force (oB) yield strength (o0.2) elongation (õ,%).

The species were cut in the longitudinal and transverse directions and at an angle of 45 ° relative to the direction of lamination.

The results of the mechanical tests are presented in Table 2. Table 2 shows that the proposed alloy replaces the known alloy (the prototype) in the ductility characteristics with preservation of the requested force characteristics.

Example 2

Sections (angles with flange thickness greater than 5 mm) were made from round ingots having a diameter of 190 mm in each alloy.

Sections of the different alloys were fabricated based on a flow process by extrusion at a temperature of 400 ° C, with another section of quench water, and aging at 150 ° C in 24 hours. The yield from the sheets of the alloys in the. 2, 3, 4 was greater than 15% when compared to alloy no. 1.

Example 3

Matrix castings with a wall thickness of 40 mm were fabricated from round ingots having a diameter of 350 mm in each alloy. 9

Table 2

League Composition League N °. Sample direction Mechanical properties &lt; Ob, ΜΠα ^ 0.2, ΜΠα σ,% Prototype 1 longitudinal 432 347.5 13.5 transverse 440 343 10.7 at an angle of 45 ° 419 323 13.9 Claim 2 longitudinal 430 349 14.6 transverse 438 352 13.8 at an angle of 45 ° 424 328 14.5 3 longitudinal 431 351 14.8 transverse 438 345 13.9 at an angle of 45 ° 425 329 14.9 4 longitudinal 432 345 14.9 transverse 439 339 14.1 at an angle of 45 ° 423 328 15.1

The matrix castings in the different alloys were fabricated in a flow process by smelting by suppression at a temperature of 410øC, preliminary melting at a temperature of 410øC and after etching by the final melt at a temperature of 400ø C, quenched at a temperature of 500 ° C for 2 hours and aging at 150 ° C for 24 hours. The yield of melt-to-die casting in alloy No. 2, 3, 4 was higher than alloy No. 1 by 10%. 10

Thus, the suggested alloy assures the achievement of the stated objective - improvement of the ductility characteristics of the alloy, and consequently improvement of its processability, increase of yields by the manufacture of semi-finished products and their parts, safety of the possibility of producing fine sheets, thin and die-cast wall sections by reducing the output of the work intensity, retention of the required force, and alloy operating characteristics and required parts of the structural materials for aerospace engineering.

Lisbon, 20 April 2010. 11

Claims (6)

Aluminum alloy containing lithium, copper, magnesium, zirconium, beryllium, titanium, nickel, manganese, gallium, zinc, sodium, which differs in that it additionally contains calcium, and at least one element selected from a group including vanadium and scandium, with the following proportion of components, wt%: 1.6 - 1.9 Copper 1.3 - 1.5 Magnesium 0.7 - 1.1 Zirconium 0.04 - 0.2 Beryllium 0.02 - 0.2 Titanium 0.01 - 0.1 Nickel 0.01 - 0.15 Manganese 0.01 - 0.2 Gallon to 0. 001 Zinc 0.01 - 0.3 Sodium up to 0. 0005 Calcium 0.005 - 0.02 and at least one element selected from a group including: Vanadium Scandium Aluminum 0.005 - 0.01 0.005 - 0.01 Remainder 2. Semi-finished product, such as sheet, plate, plate, die cast or extrudate manufactured from of the aluminum-based alloy according to claim 1. A part made from a semi-finished product according to claim 2, such as a panel of a fuselage structure of an airplane, an element of a protective structure, a welded fuel tank or any other element of aerospace engineering. A method of manufacturing an aluminum-based alloy according to claim 1, including melting of the degassing and ingot molding of the filler material carried out at a temperature of 710-730 ° C. 1 A method according to claim 4, comprising the manufacture of a sheet of flat ingots, the sheets being fabricated on the basis of a flow process by means of hot rolling at a temperature of 430øC, up to 6.5 mm thick with winding of coils, and thereafter, after annealing at a temperature of 400 ° C, by cold rolling. A method according to claim 5 including the manufacture of die castings having a wall thickness of 40 mm from round ingots having a diameter of 350 mm. A method according to claim 5, comprising the manufacture of die castings in a flow process by means of die-casting at 410øC, preliminary casting at a temperature of 410øC, and after casting by casting final temperature at 400 ° C and with additional quenching at 500 ° C for two hours and aging at 150 ° C for 24 hours. Lisbon, April 20, 2010. 2