RU2425165C1 - Heat resistant deformed alloy on base of aluminium and item made of it - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: alloy and item of it contain components at following ratio, wt %: copper - 4.4-5.4, magnesium - 0.45-0.80, manganese - 0.3-0.5, titanium - 0.03-0.10, zirconium - 0.08-0.15, chromium - 0.05-0.15, scandium -0.08-0.15, silicon - 0.03-0.25, silver - 0.4-0.80, germanium - 0.05-0.20, nickel - 0.01-0.50, iron - 0.01-0.50, aluminium - the rest. Also sum of manganese, titanium, zirconium, chromium and scandium should amount to 0.70-1.05 at ratio of scandium/zirconium = 1-1.875 and nickel/iron = 0.95-1.05. ^ EFFECT: production of semi-finished articles and items of disclosed alloy with uniform non-re-crystallised structure through whole volume and correspondingly high strength characteristics both at room and higher temperature. ^ 2 cl, 2 tbl, 1 ex

Description

The invention relates to the field of metallurgy, in particular to deformable aluminum-based alloys used as a structural material in heating parts.

Known heat-resistant deformable alloy based on aluminum of grade D21 of the aluminum-copper-magnesium system, designed for use in warming parts of aircraft and containing, wt.%:

copper 6.0-7.0 magnesium 0.25-0.45 manganese 0.4-0.8 titanium 0.1-0.2 aluminum rest

(OST 190048-90 "Deformable aluminum alloys").

It is recommended to use the alloy for the main loaded parts of the aircraft, which are subjected to operational heating to a temperature of 175 ° C.

The disadvantage of this alloy is its low long-term strength and low crack resistance characteristics, which does not allow the use of semi-finished products from this alloy for the manufacture of highly loaded structural parts subjected to alternating loads, in which a high probability of the appearance of fatigue cracks can lead to failure.

Known heat-resistant deformable alloy based on aluminum, intended for the manufacture of warming parts of aircraft and containing, wt.%:

copper 5.5-6.5 magnesium 0.2-0.35 manganese 0.4-0.8 titanium 0.05-0.1 zirconium 0.06-0.2 vanadium 0.05-0.15 molybdenum 0.02-0.08 silicon 0.12-0.25 aluminum rest molybdenum: vanadium 1: 2

(RU No. 2048577, published on November 20, 1995).

The alloy has an average level of strength properties at room temperature and elevated to 175-200 ° C.

The disadvantage of this alloy is the low level of strength characteristics at room and elevated temperatures, which limits the scope of this alloy and allows you to make from it only parts with a limited level of performance.

Closest to the proposed invention is a heat-resistant deformable alloy based on aluminum, intended for the manufacture of heating parts of aircraft and containing, wt.%:

copper 4.4-5.4 magnesium 0.45-0.8 manganese 0.4-0.8 titanium 0.03-0.15 zirconium 0.05-0.20 vanadium 0.05-0.15 molybdenum 0.01-0.15 silicon 0.03-0.25 silver 0.4-0.8 germanium 0.05-0.20 nickel 0.01-0.50 iron 0.01-0.5 aluminum rest,

the sum of manganese, titanium, zirconium, vanadium and molybdenum should be 0.55-1.0 (RU No. 2226568, publ. 10.04.2004), the prototype.

Hot-pressed products from this alloy in a heat-treated state have a higher level of strength characteristics at room temperature and elevated to 200 ° C due to the selected composition and obtaining products with an unrecrystallized structure.

The disadvantage of the alloy is the receipt in some semi-finished products and products after heat treatment of a heterogeneous (mixed) or fully recrystallized structure. This is a consequence of the tendency of the alloy to recrystallize if deformation during the manufacturing process of products, for example, cold-rolled sheets, occurs at a temperature below 300 ° C. Recrystallization during hardening heat treatment is a negative phenomenon, leading to a decrease in strength. A change in the structure from unrecrystallized to recrystallized in heat-treated semi-finished products and products obtained from them leads to a wide range of mechanical properties and characteristics of deformation resistance at elevated temperatures.

The objective of the invention is the development of an alloy having high strength characteristics for all types of semi-finished products and parts in a heat-treated state at room and elevated temperatures for short and long-term loads.

To solve this problem, a heat-resistant wrought alloy based on aluminum is proposed, containing, wt.%:

copper 4.4-5.4 magnesium 0.45-0.8 manganese 0.3-0.5 titanium 0.03-0.10 zirconium 0.08-0.15 chromium 0.05-0.15 scandium 0.08-0.15 silicon 0.03-0.25 silver 0.4-0.8 germanium 0.05-0.2 nickel 0.01-0.5 iron 0.01-0.5 aluminum rest,

the sum of manganese, titanium, zirconium, chromium and scandium should be 0.70-1.05 with the ratios scandium / zirconium = 1-1.875 and nickel / iron = 0.95-1.05 and the product made of this alloy.

The proposed alloy and the product made from it differs from the prototype in that the alloy additionally contains chromium and scandium in the following ratio of components, wt.%:

copper 4.4-5.4 magnesium 0.45-0.80 manganese 0.3-0.5 titanium 0.03-0.10 zirconium 0.08-0.15 chromium 0.05-0.15 scandium 0.08-0.15 silicon 0.03-0.25 silver 0.4-0.8 germanium 0.05-0.20 nickel 0.01-0.50 iron 0.01-0.50 aluminum rest,

the sum of manganese, titanium, zirconium, chromium and scandium should be 0.70-1.05 with the ratios scandium / zirconium = 1-1.875 and nickel / iron = 0.95-1.05.

Semi-finished products and products from the proposed alloy have a non-crystallized structure that is uniform throughout the semi-finished product and, accordingly, high strength characteristics both at room and at elevated temperature. The uniformity of the structure provides a small dispersion of properties.

The proposed chemical composition of the alloy provides high resistance to recrystallization and, accordingly, high thermal stability of the deformed structure. This allows you to use intense plastic deformation to obtain semi-finished products and products with a stable submicrocrystalline structure, which is preserved during high-temperature hardening.

The increased thermal stability of the deformed structure of the product from the proposed alloy is due to the presence of transition metals (manganese, titanium, zirconium, chromium and scandium). Semi-finished products from the proposed alloy have a high density dispersoid from small inclusions of the most effective transition metal aluminides. The scandium additive forms dispersed secondary particles of Al ₃ Sc, which are stabilized by partially dissolving Zr, Ti, Cr in them. Mn additive forms its dispersoid in a different size range, further stabilizing the non-crystallized structure of the product.

This allows you to provide high resistance to recrystallization after hot and warm deformation, including the use of equal channel angular pressing or cold rolling. The non-recrystallized sub-fine-grained structure, resistant to coarsening at the operating temperature, allows to obtain increased long-term strength and thereby increases the service life of products - and, as a result, increase the service life of aircraft.

An example implementation.

The alloys of the composition shown in Table 1 were prepared in an electric furnace, of which the castings were cast using the semi-continuous method of ingots with a diameter of 107 mm. The ingots from the prototype alloy and the proposed alloy after homogenization and machining to a diameter of 95 mm at a temperature of 400 ° C were deposited along the generatrix to a size of 40 × 177 × 200 mm. The obtained preforms were subjected to equal channel angular pressing (ECAP) at a temperature of 300 ° C in three passes through a 40 × 177 mm cross-sectional matrix and then at room temperature they were rolled onto a 2 mm thick sheet. The resulting sheets were subjected to hardening heat treatment: quenching in water after heating for 20 minutes at a temperature of 525 ° C and artificial aging according to the regime of 190 ° C for 6 hours.

The obtained material with an unrecrystallized sub-crystalline structure was subjected to tests to determine the temporary resistance σ _B , yield strength σ _0.2 , elongation δ, and long-term strength σ ₁₀₀₀ ¹⁷⁵ for 1000 h at 175 ° C. The mechanical tensile properties were determined at room temperature and at 175 ° C. The test results are shown in table 2.

The data of table 2 show that the proposed alloy in comparison with the prototype increased strength by 30-50 MPa at room and elevated temperatures and higher long-term strength.

In the proposed alloy, there are no vanadium and molybdenum available in the prototype, which are replaced by more effective chrome and scandium anti-recrystallizers.

Thus, thermally hardened semi-finished products and products with a submicroscopic structure of the proposed alloy have a unique combination of service characteristics at room and elevated temperatures.

Table 1. The chemical composition of the alloys (wt.%) Alloy Cu Mg Mn Ti Zr V Mo Cr Sc Si Ag Ge Ni Fe Al Proposed 5,0 0.6 0.4 0.06 0.12 - - 0.1 0.12 0.2 0.55 0.13 0.08 0,07 ost Prototype 4.9 0.6 0.58 0.04 0.10 0.05 0,03 - - 0.2 0.50 0.14 0.10 0.11 ost

Table 2. Mechanical properties of products in the longitudinal direction Alloy Properties at 20 ° C Properties at 175 ° C σ ₁₀₀₀ ¹⁷⁵ , MPa σ _B , MPa σ _0.2 , MPa δ,% σ _B , MPa σ _0.2 , MPa 5,% Proposed 550 490 10 425 390 10 225 Prototype 500 440 9 380 360 eleven 200

Claims (2)

1. Heat-resistant wrought alloy based on aluminum, containing copper, magnesium, manganese, titanium, zirconium, silicon, silver, germanium, nickel, iron, characterized in that it additionally contains chromium and scandium in the following ratio, wt.%:
Copper 4.4-5.4 Magnesium 0.45-0.80 Manganese 0.3-0.5 Titanium 0.03-0.10 Zirconium 0.08-0.15 Chromium 0.05-0.15 Scandium 0.08-0.15 Silicon 0.03-0.25 Silver 0.4-0.80 Germanium 0.05-0.20 Nickel 0.01-0.50 Iron 0.01-0.50 Aluminum Rest,
the sum of manganese, titanium, zirconium, chromium and scandium should be 0.70-1.05 with the ratios of scandium / zirconium = 1-1.875 and nickel / iron = 0.95-1.05. 2. A product of a heat-resistant wrought alloy based on aluminum, characterized in that it is made of an alloy according to claim 1.