RU2699422C1 - Deformed aluminum-calcium alloy - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy of aluminum-based materials and can be used for fabrication of deformed semi-finished products intended for production of critical parts operated under high loads at temperatures of up to 300–350 °C. Among them: parts of automobile engines, parts of shipbuilding, water intake fittings, etc. Proposed aluminum-based alloy contains, wt%: 2.0–2.6 Ca; 1.5–2.5 Mg; 0.4–0.6 Fe; 0.3–0.5 Si; 0.8–1.2 Mn; 0.10–0.15 Zr; 0.08–0.12 Sc; the rest is aluminum. Due to high thermal stability of structure strength properties of alloy after heating at temperatures of up to 350 °C and holding for up to 10 hours are not reduced.

EFFECT: invention is aimed at creation of a new economically alloyed heat-resistant alloy intended for production of deformed semi-finished products with high level of mechanical properties at maintaining plasticity.

3 cl, 2 dwg, 2 tbl, 2 ex

Description

The invention relates to the field of metallurgy of aluminum-based materials and can be used for the manufacture of deformed semi-finished products designed to produce critical parts operating in a corrosive environment and allowing heating to 350 ° C. Among them: automotive engine parts, shipbuilding parts, water intake fittings, etc.

Wrought thermally unstrengthened aluminum alloys of the AMg2 type, containing 2-3% Mg (hereinafter, mass%, unless otherwise specified), have high processability and corrosion resistance, as a result of which they are widely used in various fields [Phase composition of industrial and promising aluminum alloys. ON. Belov. M: Publ. MISiS House, 2010 - 511 s. ISBN 978-5-87623-375-2]. These alloys are intended primarily for sheet metal. The main disadvantage of the AMg2 alloy is its low strength, especially in the annealed state (according to GOST 21631-76, the requirement for temporary resistance is less than 200 MPa). This prevents their use in loaded products. An increase in the magnesium content up to 5-6% (AMg5, AMg6 alloys) can significantly increase strength, however, this reduces manufacturability (in particular, resistance to deformation) and corrosion resistance (due to the formation of secondary precipitates of the Al ₃ Mg ₂ phase along grain boundaries) [Phase composition of industrial and promising aluminum alloys. ON. Belov. M: Publ. MISiS House, 2010 - 511 s. ISBN 978-5-87623-375-2]. In addition, ingots of high magnesium alloys require homogenizing annealing.

To increase the strength properties of aluminum-magnesium alloys of the type, it is advisable to additionally alloy them with such elements that would maintain a high level of manufacturability and corrosion resistance. Among them are scandium and zirconium, which are used in alloys of type 01570 [Reznik, Pavel Lvovich; Chikova, Olga Anatolyevna; Ovsyannikov, B.V. / Effect of ingot homogenization modes on the microstructure, phase composition and mechanical properties of 01570 alloy at elevated temperatures. In: Metallurgy and heat treatment of metals. 2016; No. 4 (730). p. 18-22]. The latter are currently considered as one of the most promising materials for the aircraft industry, since they make it possible to achieve significantly greater strength compared to classical magnalias. This hardening is achieved due to the presence of Al ₃ (Sc, Zr) -Ll ₂ phase nanoparticles in the structure of the deformed semi-finished products, which are effective anti-recrystallizers. These nanoparticles are formed during annealing (or technological heating) of ingots during the decomposition of a supersaturated aluminum solid solution (hereinafter (Al)), which is formed during crystallization.

Known alloy disclosed in patent RU 2226565 (publ. 10.04.2004, bull. No. 10). This alloy, intended for the manufacture of deformed semi-finished products, contains 5-6 wt. % magnesium (Mg), 0.05-0.15 wt. % zirconium (Zr), 0.05-0.12 wt. % manganese (Mn), 0.01-0.2 wt. % titanium (Ti), 0.05-0.5 wt. % of one or more elements of the group consisting of scandium (Sc), terbium (Tb), cerium (Ce) and other lanthanides, while it contains at least scandium (Sc), in addition, 0.1- 0.2 wt. % copper (Cu) and / or 0.1-0.4 wt. % zinc (Zn), as well as aluminum (Al) and the inevitable inclusion of silicon in an amount of a maximum of 0.1 wt. % In a private embodiment, the alloy contains at least 0.15 wt. % scandium (Sc).

The disadvantage of this alloy is its high magnesium content, which requires a homogenization operation in a narrow temperature range. Another disadvantage of this alloy is the strict restriction on the content of iron and silicon, which excludes the possibility of its preparation on the basis of primary aluminum of low grades, as well as the use of secondary raw materials. Another disadvantage of this alloy is the high content of expensive scandium in its composition.

Closest to the proposed is a corrosion-resistant aluminum-magnesium alloy disclosed in the patent of the Russian Federation No. 2478131 This alloy contains 3-5 wt. % magnesium (Mg), 0.05-0.15 wt. % zirconium (Zr), 0.05-0.12 wt. % manganese (Mn), 0.01-0.2 wt. % titanium (Ti), 0.05-0.5 wt. % of one or more elements from the scandium group and / or terbium (Tb), while it contains at least scandium (Sc), as well as aluminum (A1) and the inevitable inclusion of silicon in an amount of a maximum of 0.2 wt. % In a private embodiment, this alloy contains at least 0.15 wt. % scandium (Sc). The alloy is intended for the manufacture by welding, rolling, extrusion or forging parts for an air vehicle, especially the fuselage of an aircraft, for a sea vehicle or for a motor vehicle.

The disadvantage of this alloy is a strict restriction on the content of iron and silicon, which excludes the possibility of its preparation on the basis of primary aluminum of low grades, as well as the use of secondary raw materials. Another disadvantage of this alloy is the high content of expensive scandium in its composition.

The technical result is the creation of a new corrosion-resistant alloy based on aluminum, designed to produce deformed semi-finished products and allowing its composition not less than 0.4% iron, not less than 0.3% silicon, not more than 2.5% magnesium and not more than 0.12 % scandium. This alloy must allow heating up to 350 ° C inclusive.

The technical result is achieved in that the deformed aluminum-based alloy containing magnesium, manganese, zirconium, scandium and silicon, characterized in that it additionally contains calcium and iron at the following concentrations of alloying components, mass. %:

Calcium 2.0-2.6 Magnesium 1.5-2.5 Iron 0.4-0.6 Silicon 0.3-0.5 Manganese 0.8-1.2 Zirconium 0.10-0.15 Scandium 0.08-0.12 Aluminum the basis

The alloy of this composition can be made in the form of sheets with the following tensile properties after 3 hours of heating at 350 ° C: temporary resistance (σv) of at least 300 MPa, elongation (δ) of at least 5%. The alloy of this composition can also be made in the form of rods with the following tensile properties after 3 hours of heating at 350 ° C: temporary resistance (σv) of at least 350 MPa, elongation (δ) of at least 5%.

The invention is illustrated in the drawing, where in FIG. 1 shows deformed semi-finished products made of the inventive alloy of composition No. 3 in the form of sheet metal, in FIG. 2 shows deformed semi-finished products made of the inventive alloy of composition No. 3 in the form of rods.

The invention consists in the following.

Calcium allows you to bind iron and silicon and ternary compounds, which have a favorable morphology and do not adversely affect the mechanical properties and corrosion resistance. The concentration of magnesium and manganese within the stated limits provides the necessary level of strength properties while maintaining a sufficiently high deformation ductility.

Concentrations of zirconium and scandium within the stated limits provide the necessary dispersion hardening effect due to the formation of an Al ₃ (Zr, Sc) phase with an Ll ₂ lattice with high thermal stability during annealing of nanoparticles.

EXAMPLE 1

6 alloys were prepared, the compositions of which are indicated in table. 1. All alloys were prepared in an electric resistance furnace in graphite chamotte crucibles based on primary aluminum grade A5E. Flat ingots were prepared from these alloys, from which sheets of 2 mm thickness were obtained on a rolling mill (Fig. 1). Samples of the sheets were subjected to stabilizing annealing at 350 ° C for 3 hours in a muffle electric furnace.

Mechanical properties (tensile strength - σ _in , conditional yield strength - σ _0.2 and elongation - δ) were determined by the results of uniaxial tensile tests on a Zwick Z250 machine. Tests at room temperature were carried out according to GOST 1497-84. Corrosion resistance was evaluated by weight loss (Δm) after exposure to an aqueous solution of 3% NaCl + 0.3% H ₂ O ₂ during the day.

¹ mass loss after corrosion tests

From the table. 1 it is seen that only the claimed alloy (compositions 2-4) provides the best combination of temporary resistance, yield strength and elongation. In alloy 1, the strength is less than the required level, which is associated with an insufficient amount of precipitation of the phases Al ₆ Mn and Al ₃ (Zr, Sc). Alloy 5 has a low value of δ, which is associated with the presence of primary crystals of intermetallic compounds. An alloy that differs from alloy 3 in the absence of calcium (composition 6) is inferior to alloys 2-4 in mechanical properties, which is the binding of a part of magnesium to the compound Mg ₂ Si. In addition, alloy 6 has a lower corrosion resistance.

EXAMPLE 2

Cylindrical ingots were prepared from the inventive alloy of composition No. 3, from which bars of 14 mm and 9 mm in diameter were obtained from the radial-shear mill (Fig. 2). These rods did not contain cracks or other visible defects. The mechanical properties are given in table. 2, show a high level of strength properties.

Claims (4)

1. A deformable aluminum-based alloy containing magnesium, manganese, zirconium, scandium and silicon, characterized in that it additionally contains calcium and iron at the following concentrations of alloying components, wt.%: Calcium 2.0-2.6 Magnesium 1.5-2.5 Iron 0.4-0.6 Silicon 0.3-0.5 Manganese 0.8-1.2 Zirconium 0.15-0.25 Scandium 0.08-0.12 Aluminum The basis 2. The alloy according to claim 1, characterized in that it is made in the form of sheets having, after 3 hours of heating at 350 ° C., a temporary resistance (σv) of at least 300 MPa, a relative elongation (δ) of at least 5%. 3. The alloy according to claim 1, characterized in that it is made in the form of rods having, after 3 hours of heating at 350 ° C., a temporary resistance (σv) of at least 350 MPa, a relative elongation (δ) of at least 5%.

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