RU2579861C1 - Method for production of deformed semi-finished products of aluminium-based alloy - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly to deformable alloys based on aluminium system Al-Fe-Si in form of rolled sheets, foils, sheets, plates, extrusions, wire and others. From deformed semi-finished products can be obtained article to be used as packaging material food products, products used in construction as decorative finishing material, chemical industry for storage and transportation of different chemical substances, etc, method for production of deformed semi-finished products from aluminium alloy includes preparation of melt containing aluminium, iron and silicon ingot by melt crystallisation, production of deformed semi-finished products by deformation of ingot and annealing of deformed semi-finished products, wherein melt is prepared based on produced on technology of inert anode, with following ratio of components in molten, wt%: iron - 0.5-1.6, silicon - 0.25-0.4, aluminium - balance, at ratio of iron to silicon content of 2-4, melt crystallisation is performed at cooling rate not less than 20 K/s, deformation of ingot is performed at least in 2 stages with intermediate annealing between stages at 300-450 °C, at first stage with deformation degree of not less than 90 %, at next stage with deformation degree of not less than 60 %, annealing of the ready deformed semi-finished product is performed at 300-400 °C, wherein deformed semi-finished products with structure containing aluminium matrix with silicon content up to 0.1 wt% and uniformly distributed particles phase Al₈Fe₂Si with average size of not more than 1 mcm and weight ratio of 0.5 to 2 %.

EFFECT: technical effect consists in creation of new deformed alloy in form of thin-sheet rolled plate, foil and wire with high mechanical and electrical properties, particularly with time resistance after annealing, exceeding 130 MPa, electric conductivity of more than 60 % IACS, relative elongation exceeding 20 %.

5 cl, 4 dwg, 2 tbl, 3 ex

Description

Technical field

The invention relates to the field of metallurgy, in particular to wrought alloys based on aluminum of the Al-Fe-Si system in the form of rolled sheets, foils, sheets, plates, extruded profiles, wire, etc. The material can be used to obtain products operating in various environments , including corrosion. From deformed semi-finished products of the proposed alloy can be obtained products intended for use as packaging material for food products; products used in construction (as a decorative and decorative material); chemical industry (for storage and transportation of various chemicals); electrical products as wires, tires, etc.

State of the art

Deformable aluminum alloys of the Al-Fe-Si system (8xxx type 8079 series, including unalloyed aluminum 1xxx type 1050 series) are characterized by a high combination of corrosion resistance and processability in pressure processing (Alieva SG, Altman MB and others Industrial aluminum alloys, Moscow: Metallurgy, 1984. 528 p.). A significant drawback of these alloys is the wide concentration range of alloying elements (primarily in terms of Fe content) without regulation of the final structure, which can lead to a deterioration in manufacturability during pressure treatment, especially when producing sheet metal and foil, as well as a deterioration in the quality of the applied anodized coating. In particular, at a high Fe content and relatively low silicon concentrations, a predominantly Al ₃ Fe (Al ₆ Fe) phase of crystallization origin will form in the structure.

A known method of producing foil from an aluminum alloy of the Al-Fe-Si system (patent WO 2007006426 A3, NOVELIS, INC). In this invention, the authors regulated the ratio of Fe and Si and, as a result, realized the predominantly cubic α-AlFeSi phase in the structure. This made it possible to increase manufacturability during cold working with pressure (up to obtaining foil less than 200 microns) and ensured a high level of mechanical properties. The disadvantages of this method include the following: for the implementation of cold pressure molding of a cast billet (up to obtaining foil with a thickness of 200 μm or less), it is necessary to provide a high cooling rate of the ingot (cast billet) in the crystallization interval. If the cooling rate is insufficient, relatively coarse particles of the Fe-containing phase will form in the structure, which will negatively affect the mechanical properties. In addition, regulating only the ratio between Fe and Si in a wide concentration range will not allow to achieve a minimum silicon content in aluminum solid solution, which is especially important in the case of using this material in electrical engineering.

There is another method for producing sheet material from an aluminum alloy (patent US 4126487, Alcan), closest to the claimed method. The inventors have proposed a method for producing sheets from alloys of the Al-Fe and Al-Fe-Si systems, which makes it possible to achieve in the structure a regulated size of phases of crystallization origin, providing a high level of mechanical properties. The disadvantages of this invention include the possibility of the formation of various crystallization phases that can reduce manufacturability during pressure processing.

Disclosure of invention

The basis of the invention is the task of creating a new deformed alloy based on aluminum, obtained by the inert anode technology, which would have a high processability in pressure processing, a good level of mechanical, in the form of various deformable semi-finished products (rolled sheets, foil, plates, wire, etc.) properties in the annealed state (in particular, a temporary resistance of at least 130 MPa and elongation of at least 20%) and electrical conductivity of more than 60% IACS.

The problem is solved by creating a method for producing deformed semi-finished products from an aluminum alloy, including the preparation of a melt from aluminum containing iron and silicon, obtaining an ingot by crystallization of the melt, obtaining deformed semi-finished products by deformation of the ingot and annealing of the deformed semi-finished products, characterized in that the melt is prepared on the basis of aluminum, obtained by the technology of an inert anode containing

iron - from 0.5 to 1.6 mass. %

silicon - from 0.25 to 0.4 mass. %

aluminum - the rest,

when the ratio Fe / Si = 2-4, in this case, the melt crystallization is carried out with a cooling rate of at least 20 K / s, the deformation of the ingot is carried out in steps of at least 2 stages with intermediate annealing between the steps at 300-450 ° C, in the first steps with a degree of deformation of not less than 90%, subsequent deformation with a degree of reduction of not less than 60%, annealing of the finished deformed semi-finished product at 300-400 ° C, and deformed semi-finished products with a structure containing an aluminum matrix with a silicon content of not more than 0.1% are obtained and evenly distributed particles of the Al ₈ Fe ₂ Si phase with an average transverse size of not more than 1 μm and a mass fraction of 0.5 to 2%. In a particular case, the deformation of the ingot is carried out without intermediate annealing. The alloy can be made in the form of various deformed semi-finished products: rolled sheets, foil, plates, wire.

The technical result of this invention is the creation of a new deformed alloy made in the form of rolled sheets, plates, foils and wires with a high complex of mechanical and electrical properties, in particular, the temporary resistance after annealing exceeds 130 MPa, the electrical conductivity is more than 60% IACS, the elongation exceeds 20 %

SUMMARY OF THE INVENTION

When creating the invention, the task was to develop an alloy with a structure containing an aluminum matrix with a silicon content of up to 0.1% and uniformly distributed particles of the Al ₈ Fe ₂ Si phase with an average transverse size of not more than 1 μm and a mass fraction of from 0.5 to 2 % At the same time, the alloy should be suitable for its production on serial industrial equipment used for the production of wrought aluminum alloys with the following level of mechanical characteristics (on sheets): temporary resistance of at least 130 MPa, elongation of at least 20%.

The justification of the claimed technological parameters of the method for producing deformed from this alloy is given below.

During crystallization of the melt with a cooling rate of less than 20 K / s, the formation of relatively coarse Fe-containing phases of crystallization origin with an average transverse size of more than 1 μm is possible and, as a result, the processability during deformation and the surface quality of the deformed semi-finished products are deteriorated.

If the temperature of the intermediate annealing of the deformed semifinished product exceeds 450 ° C, then relatively large grains may be formed in the structure during recrystallization. If the temperature of the intermediate annealing of the deformed semi-finished product is below 300 ° C, then a long time exposure during heat treatment will be required.

If the annealing temperature of the finished deformed semifinished product exceeds 400 ° C, then relatively large recrystallized grains can be formed in the structure, leading to a decrease in elongation. If the annealing temperature of the finished deformed semifinished product is below 300 ° C, then long time holdings with soft annealing will be required.

If the melt is prepared from aluminum obtained by the inert anode technology that goes beyond: iron from 0.5 to 1.6 mass. %, silicon from 0.25 to 0.4 mass. %, with the ratio Fe / Si = 2-4, then the final structure will be an aluminum matrix with various particles of Fe-containing phases distributed in it. The presence of other Fe-containing phases can degrade processability in pressure processing. At a higher concentration of silicon, the aluminum solid solution may contain more than 0.1 mass. % Si, which will negatively affect the conductivity of the material.

Case Studies

Alloys for the claimed material were prepared in an electric resistance furnace in graphite chamotte crucibles made of aluminum, obtained by the technology of an inert anode, grade A7 aluminum (GOST 11069-2001) and double ligatures (Al-Fe and Al-Si). The alloy composition for the inventive material corresponded to compositions 2-4 in the table. 1. Flat (section 40 × 120 mm) and cylindrical ingots (diameter 44 mm) were obtained by casting in graphite molds. The number of Fe-containing phases, the concentration of silicon in the aluminum solid solution was calculated using the Thermo-Calc program (TTAL5 database). For alloy composition 3, ingots were obtained at a lower cooling rate in the crystallization interval.

Flat ingots were rolled with both intermediate annealing and without it. Wire drawing was carried out without intermediate annealing. The structure of the alloys was studied in an electron scanning microscope (TESCAN). The tensile test was carried out according to GOST 1497-84 (strain rate was 4 mm / min, the estimated length of 50 mm). The electrical resistivity (with subsequent conversion to IACS values) of the flat samples was measured using an INSTEK GOM-2 digital programmable milliometer.

Example 1

The mechanical properties and conductivity of cold-rolled sheets (0.5 mm thick) were determined after annealing at 300 ° C for 1 hour (Table 1). Scheme for producing sheets: ingot deformation with an initial ingot temperature of 450 ° C (without heating) to a sheet 4 mm thick, then intermediate annealing at 400 ° C for 1 hour and subsequent deformation at room temperature to a sheet of 0.5 mm.

From the results presented in table 1, it follows that only the claimed alloy of compositions 2-4 satisfies the requirements in the annealed condition in terms of mechanical properties, conductivity (temporary resistance more than 130 MPa, elongation above 20% and IACS more than 60%) and silicon content in aluminum solid solution.

Example 2

To justify the cooling rate in the crystallization interval, the ingots of the inventive alloy of composition 3 (table. 1) were obtained at different speeds (table. 2).

From the results presented in the table and in figure 1 (Typical microstructure of an alloy of composition 3 of Table 1), it can be seen that at cooling rates in the crystallization interval above 20 K / s, a given structure with a transverse size of Fe-containing particles with an average transverse size of more than 1 micron. At a lower cooling rate, the structure is substantially roughened, for example, in figure 2 (the structure of alloy 3 (Table 1) obtained at a cooling rate of less than 1 K / s) it is shown that at a rate of less than 1 K / s the size of the Fe-containing phases can reach more than 2 microns.

Example 3

The processability during pressure processing was assessed on cast flat (40 mm high) and cylindrical (44 mm diameter) ingots of composition 3 (Table 1), which were subjected to deformation without intermediate annealing to foils with a thickness of less than 50 microns (rolling) and wire with a diameter of less than 200 μm (drawing), photographs of the foil are shown in FIG. 3 (foil and sheet products from alloy composition 3 (table. 1)) and FIG. 4 (wire from alloy composition 3 (table. 1)).

Claims (5)

1. A method of obtaining a deformed semi-finished product from an aluminum alloy, including the preparation of a melt containing aluminum, iron and silicon, obtaining an ingot by crystallization of the melt, obtaining a deformed semi-finished product by deformation of the ingot and annealing the deformed semi-finished products, characterized in that the melt is prepared on the basis of aluminum obtained by aluminum inert anode technology, in the following ratio of components in the melt, wt. %:
iron - 0.5-1.6,
silicon - 0.25-0.4,
aluminum - the rest,
when the ratio of iron to silicon is 2-4, melt crystallization is carried out with a cooling rate of at least 20 K / s, the ingot is deformed in at least 2 stages with intermediate annealing between stages at 300-450 ° C, at the first stage with a degree deformation of not less than 90%, at a subsequent stage with a degree of deformation of not less than 60%, the finished deformed semi-finished product is annealed at 300-400 ° C, and deformed semi-finished products with a structure containing an aluminum matrix with a silicon content of up to 0.1 wt. % and uniformly distributed particles of the Al ₈ Fe ₂ Si phase with an average transverse size of not more than 1 μm and a mass fraction of from 0.5 to 2%. 2. The method according to p. 1, characterized in that the deformed semi-finished product is performed in the form of sheet metal. 3. The method according to p. 1, characterized in that the deformed semi-finished product is made in the form of foil. 4. The method according to p. 1, characterized in that the deformed semi-finished product is made in the form of a plate. 5. The method according to p. 1, characterized in that the deformed semi-finished product is made in the form of a wire.

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