RU2573164C1 - High-strength wrought aluminium-based alloy - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy of alloys, particularly, to high-strength wrought Al-Cu-Mg-Ag-system-based aluminium alloys to be used as high-strength structural materials in aerospace engineering. Proposed composition contains the following substances, in wt %: copper - 4.0-5.5, magnesium - 0.2-0.8, manganese - 0.2-0.6, silver - 0.4-0.8, titanium - 0.05-0.2, chromium - 0.02-0.1, zirconium - 0.05-0.2, vanadium - <0.1, zinc - <0.25, iron <0.1, silicon <0.1, aluminium making the rest.

EFFECT: higher strength.

2 ex, 3 tbl

Description

The present invention relates to the field of metallurgy of alloys, in particular deformable heat-hardenable aluminum alloys of the Al-Cu-Mg-Ag system, intended for use as high-strength structural materials in the aerospace industry.

Heat-resistant aluminum alloys of the Al-Cu-Mg system alloyed with silver are widely used in the aerospace industry and mechanical engineering. They found their main application as materials for the manufacture of various elements of the power set and cladding of the fuselage, wing, aircraft, power structural elements in the automotive industry. These alloys are characterized by a unique combination of strength characteristics and high fracture toughness. However, continuous improvement of the structures used and the desire to improve the properties of the material in order to reduce the cost of operation, maintenance and repair, improve the economy and characteristics of the product lead to the search for new alloys that provide the necessary set of properties.

Known high-strength alloy series AA2000 based on aluminum (US No. 5652063, publ. 07.29.1997), the following composition (wt.%):

Copper 4.85-5.3

Magnesium 0.5-1.0

Manganese 0.4-0.8

Silver 0.2-0.8

Zirconium 0.05-0.25

Silicon ≤ 0.1

Iron ≤ 0.1

A preferred Cu / Mg ratio is between 5 and 9 and most preferred is between 6 and 7.5.

Also known is a high-strength alloy of the Al-Cu-Mg system for operation in the temperature range from 0 ° C to 250 ° C (US No. 4772342, publ. 09/20/1988).

The chemical composition of the present invention (in wt.%):

Copper 5-7

Magnesium 0.3-0.8

Silver 0.2-1

Manganese 0.3-1

Zirconium 0.1-0.25

Vanadium 0.05-0.15

Silicon <0.1

In the T6 state, this alloy has the following strength characteristics: at room temperature, the tensile yield strength is 510 MPa, at 200 ° C the same indicator is 400 MPa, and at 250 ° C about 300 MPa. The creep strength at 180 ° C after 500 hours of exposure is 250 MPa.

Closest to the proposed invention is an Al-Cu-Mg alloy, suitable for aerospace applications (RU No. 2418876, publ. 05.20.2011), the following composition (wt.%):

Copper 4.1-5.5

Magnesium 0.30-1.6

Manganese 0.15-0.8

Titanium 0.03-0.4

Chrome 0.05-0.4

Silver <0.7

Zirconium <0.2

Iron <0.20, preferably <0.15

Silicon <0.20, preferably <0.15

The remainder is aluminum and other impurities or random elements, each <0.05%, in total <0.15%.

The mechanical properties of the alloy in the T3 state at room temperature are equal: yield strength tensile 328-334 MPa, tensile strength 441-466 MPa, elongation to failure ~ 22%.

Existing alloys have a sufficient level of mechanical properties, however, to create new designs that meet the requirements of economy and efficiency, you need a material whose performance characteristics exceed the achieved level. Thus, there is a need to create a new alloy having an improved complex of proper mechanical properties.

The main objective of the invention is the development of an aluminum alloy of the Al-Cu-Mg-Ag system, which has a higher level of mechanical properties compared to existing alloys (impact strength, conditional yield strength, tensile strength, elongation after rupture).

The problem is solved due to the fact that in the aluminum-based alloy containing copper, magnesium, manganese, silver, titanium, chromium, zirconium, iron, silicon, vanadium and zinc are additionally introduced, and the content of iron and silicon is reduced, and the components are taken in the following ratios, wt. %:

Copper from more than 5.0 to 5.5

Magnesium 0.2-0.8

Manganese 0.2-0.6

Silver 0.4-0.8

Titanium 0.05-0.2

Chrome 0.02-0.1

Zirconium 0.05-0.2

Vanadium <0.1

Zinc <0.25

Iron <0.1

Silicon <0.1

Aluminum - the rest

The presence of copper, magnesium and silver in the alloy provides the formation of an additional finely dispersed hardening Ω-phase, due to which the alloys of this alloying system have a unique set of mechanical properties, such as high strength, creep resistance and fracture toughness, significant fatigue life. Complex alloying with transition metals, such as manganese, titanium, zirconium and vanadium, with a relatively low content of each component, allows to increase the density of dispersed particles and to avoid the appearance of primary intermetallic compounds during casting of the alloy.

The technical result of the invention is an alloy having improved mechanical strength characteristics, which can be used in the manufacture of semi-finished products in the form of rolled plates and sheets, forgings and pressed rods.

Examples of implementation

Example 1

Two alloys were cast: the prototype and the proposed chemical composition (table 1). The alloys were homogenized at 525 ° C for 24 hours. Next, hot rolling at 420 ° C to a total degree of deformation of ~ 80% followed, cold rolling with a degree of deformation of ~ 70% and quenching of workpieces from 510 ° C (holding for 1 h) to cold water. Then, the obtained semi-finished products were kept at room temperature for 4 hours, followed by sheet stretching by 2% strain and natural aging for 5 days (T3 state).

Table 1 presents the chemical composition of the proposed alloy and prototype, and the results of a comparison of mechanical tensile tests according to GOST 1497-84 at room temperature are presented in table 2 (state T3). Samples were cut along the rolling direction.

Table 1

Cu Mg Mn Ag Ti Zr Zn V Cr Fe Si Al Prototype 5.1 0.58 0.3 0.2 0.1 <0.01 - - <0.004 <0.06 <0.04 Ost. Suggested Alloy 4.7 0.5 0.35 0.5 0.15 0.14 0.2 0.05 0.04 <0.04 <0.03 Ost.

table 2

Prototype Suggested Alloy σ _0.2, MPa σ _in , MPa δ,% σ _0.2, MPa σ _in , MPa δ,% 335 466 22.6 360 490 twenty

In table 2: σ _0.2 - conditional yield strength; σ _in - ultimate strength; δ,% - elongation after rupture.

As can be seen from table 2, the mechanical properties of the proposed alloy is significantly higher than the prototype. This allows you to apply the present invention in the practical production of various semi-finished products, such as forgings, plates, sheets, welded parts.

Example 2

The proposed alloy with the content of alloying elements, as shown in table 1, was obtained by casting, then the ingot was homogenized at 525 ° C for 24 hours. Then, rods were cut from the obtained workpiece, which were subjected to equal channel angular pressing at 400 ° C to the total degree of deformation ~ 2. Then, the obtained billet was quenched in water from a temperature of 520 ° C for 1 h, and subjected to cold rolling to a total degree of deformation of ~ 20% and artificial aging at 190 ° C for 2 h (state T82). Samples for mechanical tests were cut along and across the rolling direction, the test results at room temperature are shown in table 3. Mechanical tensile tests were carried out according to GOST 1497-84, for the determination of impact strength - according to GOST 9454-78, type of sample KCV.

The mechanical properties of the proposed alloy in the state of T82 at room temperature are shown in table 3.

Table 3

Sample Number σ _0.2, MPa σ _in , MPa δ,% Impact strength, J / cm ² one 490 540 10.5 33.5 2 495 535 10.0 34.0

Thus, the proposed chemical composition of the alloy has a unique set of mechanical properties, such as: high strength, creep resistance and fracture toughness, significant fatigue life. Significantly improved characteristics of the aluminum alloy will allow the manufacture of parts for the aerospace industry. The alloy can be processed to products of various shapes, for example, a sheet, plate, forged product, extruded bar, can be uncoated or may be coated in order to further improve the corrosion properties.

Claims (1)

High-strength wrought aluminum-based alloy containing copper, magnesium, manganese, silver, titanium, chromium, zirconium, iron and silicon, characterized in that it additionally contains vanadium and zinc in the following ratio, wt. %:
copper from more than 5.0 to 5.5 magnesium 0.2-0.8 manganese 0.2-0.6 silver 0.4-0.8 titanium 0.05-0.2 chromium 0.02-0.1 zirconium 0.05-0.2 vanadium <0.1 zinc <0.25 iron <0.1 silicon <0.1 aluminum rest