KR100755128B1 - Method of manufacturing aluminum alloy having high electro-conductivity and heat resistance, Aluminum alloy wire and Overhead transmission line manufactured using the same - Google Patents

Abstract

The present invention discloses a method for producing an aluminum alloy wire having high conductivity and high heat resistance. The manufacturing method of the aluminum alloy wire which concerns on this invention is a manufacturing method of Al-Zr-Fe-Si type aluminum alloy wire, 0.2-0.4 weight% zirconium, 0.05-0.2 weight% iron, and 0.05-0.2 weight% silicon Is added as an ingredient, and the sum of the components of iron and silicon does not exceed 0.3% by weight, and a raw material containing aluminum as the main component is injected in the state of (A) molten alloy in the temperature range of 750 ° C to 950 ° C A casting step of forming a cast aluminum alloy wire by starting rolling and extrusion in a temperature range of 450 to 550 ° C .; (B) a hot working step of firstly reducing the cross-section of the cast aluminum alloy wire with a cross-sectional reduction rate of 70% or more in a temperature range that suppresses phase change and grain growth of the cast aluminum alloy wire to form a primary aluminum alloy wire; (C) cold working step of secondly reducing the cross-section of the primary aluminum alloy wire to a cross-sectional reduction rate of 85 to 90% in the temperature range that can form the precipitation nucleus of the aluminum alloy to process the secondary aluminum alloy wire; And (D) a first stage heat treatment of the secondary aluminum alloy wire at a temperature of 250 to 350 ° C. for 15 to 30 hours and a second heat treatment at a temperature of 300 to 450 ° C. for 50 to 80 hours. It characterized in that it comprises a step.

Aluminum, alloy wire, wire rod, high conductivity, high heat resistance

Description

Method of manufacturing aluminum alloy having high electro-conductivity and heat resistance, Aluminum alloy wire and Overhead transmission line manufactured using the same }

1 is a conceptual diagram schematically showing a manufacturing process of an aluminum alloy wire according to the prior art.

2 is a conceptual diagram schematically illustrating a manufacturing process of an aluminum alloy wire having high conductivity and high heat resistance according to a preferred embodiment of the present invention.

3A to 3C are schematic cross-sectional views of overhead transmission lines using aluminum alloy wires having high conductivity and high heat resistance according to a preferred embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum alloy wire, and more particularly, to a method for manufacturing an aluminum alloy wire, which is simplified by a two-stage heat treatment after cold working, and which has improved conductivity and heat resistance.

Currently, there are two transmission methods for supplying electricity to large cities or large factories through power substations in power plants, and underground transmissions through cables laid underground and overhead transmissions account for about 90% of domestic transmissions. .

Here, the conductivity of pure aluminum without addition of the alloy is about 62%, but because it is soft, a small amount of alloying element is added to increase the strength even if the conductivity is reduced for use in electric wires.

The technical trend of aluminum alloy wire for overhead transmission line is 60TAL (heat resistant aluminum alloy wire) with 60% IACS conductivity and 150 ℃ continuous use temperature in 1960s, XTAL (special heat resistant aluminum with 58% IACS conductivity and 230 ℃ continuous use temperature in 1980s Alloy wire), STAL or ZTAL at 60% IACS conductivity and 210 ° C continuous use temperature in 1985, XTAL at 58% IACS conductivity and 230 ° C continuous use temperature in 1993. .

In this case, '% IACS' indicates that the resistivity is 100 / (58 × x) Ω 2 mm 2 / m as a unit of the conductivity, and the same will be indicated in the following embodiments.

In addition, the conductivity is related to the amount of current that can flow in the aluminum conductor of the same cross-sectional area, and when the conductivity is high, more current can flow and the transmission capacity increases.

In addition, the continuous use temperature is also referred to as heat resistance temperature. When current flows through an aluminum conductor, heat is generated due to conductor resistance, and when heat is generated, all metals are softened and stretched by their own weight. Therefore, the increase in the continuous use temperature means that the change in the strength of the conductor disappears even if the current of the conductor increases due to the flow of more current, and the transmission capacity can be increased without the loss of strength caused by the heat generation.

In the above-described technology trend, the transmission capacity is determined according to the conductivity and the continuous use temperature. For example, assuming that the transmission capacity of the STAL having the conductivity and the continuous use temperature is 60% IACS and 210 ° C., respectively, 58% IACS, The transmission capacity per square area of XTAL at 230 ° C is 1.13, which increases about 13%. Therefore, in order to increase the transmission capacity of the overhead transmission line, it is necessary to increase the conductivity and the continuous use temperature, that is, the conductivity and the continuous use temperature.

However, the relationship between the conductivity and the high temperature strength according to the continuous use temperature is difficult to secure the high temperature strength when the conductivity is high, and the 'trade off' property that the conductivity is low when the high temperature strength is increased. Optimization of overheating conditions is essential.

In addition, when impurities are added to aluminum, the conductivity becomes low. Therefore, in order to increase the conductivity of Al-Zr-based aluminum alloy wire, the alloying elements should be precipitated as much as possible. In order to increase the continuous use temperature, the existing structure does not change even at a high temperature of Al. Must have an organization that does not recrystallize.

Japanese Patent Laid-Open No. 5-70,905 contains 0.15 to 0.4% by weight of zirconium, 0.1 to 0.5% by weight of iron, 0.05 to 0.2% by weight of silicon, 0.005 to 0.05% by weight of beryllium, and the sum of the content of silicon and beryllium A method for producing an aluminum alloy wire, which is 0.035 to 0.11% by weight, and the remainder is made of aluminum and impurities inevitably added.

Here, in the method of manufacturing an aluminum alloy wire according to the '905 patent, an aluminum alloy wire having high conductivity and continuous use temperature was manufactured by the manufacturing process shown in FIG. 1.

Referring to FIG. 1, the production of an aluminum alloy wire having a conductivity of 58% or more and a continuous use temperature of 230 ° C. or more is referred to as “casting (S10) → hot working (S20) → primary cold working (S30) → primary heat treatment (S40). ) → Second cold working (S50) → Secondary heat treatment (S60) ”, and forming a yellow phosphorus wire by continuous casting rolling (S10 to S20), and the sulfur phosphorus wire is 50% or more. Primary cold working at a cross-sectional reduction rate to form a primary work material (S30), the first heat treatment for 5 to 50 hours in a temperature range of 300 to 450 ℃ (S40). Subsequently, the primary processed material subjected to the primary heat treatment is secondarily cold-processed at a cross-sectional reduction rate of 50% or more to form a secondary processed material, and the secondary processed wire is 0.5 to 10 hours in a temperature range of 350 to 500 ° C. The secondary heat treatment of the aluminum alloy wire is produced.

However, the manufacturing method according to the '905 patent, because the beryllium added to increase the high temperature strength is an environmentally regulated material, which leads to an environmental problem and an increase in the production cost, and two times cold working after casting and hot working There is a complicated problem in the manufacturing method due to overheating.

In addition, the aluminum alloy wire having improved heat resistance for processing transmission has a high continuous use temperature of 230 ° C., while having a low electrical conductivity of about 58%.

The present invention was devised in consideration of the above-described conventional problems, and excludes beryllium, which is an environmental regulation material added to increase the strength of the aluminum alloy, and can simultaneously increase the conductivity and heat resistance of the aluminum alloy wire through a simple process. It is an object of the present invention to provide a method for producing an alloy wire, and an aluminum alloy wire and a overhead transmission wire produced by the method.

The method for producing an aluminum alloy wire having high conductivity and high heat resistance according to the present invention is a method for producing an Al-Zr-Fe-Si-based aluminum alloy wire, which includes 0.2 to 0.4 wt% zirconium, 0.05 to 0.2 wt% iron, and A raw material containing aluminum as the main component of 0.05 to 0.2% by weight of silicon as an additive component, so that the sum of the components of iron and silicon does not exceed 0.3% by weight, and (A) in the temperature range of 750 ° C to 950 ° C Injecting in the state of the molten alloy, the casting step of forming a cast aluminum alloy wire by starting rolling and extrusion in the temperature range of 450 to 550 ℃; (B) a hot working step of firstly reducing the cross-section of the cast aluminum alloy wire with a cross-sectional reduction rate of 70% or more in a temperature range that suppresses phase change and grain growth of the cast aluminum alloy wire to form a primary aluminum alloy wire; (C) cold working step of secondly reducing the cross-section of the primary aluminum alloy wire to a cross-sectional reduction rate of 85 to 90% in the temperature range that can form the precipitation nucleus of the aluminum alloy to process the secondary aluminum alloy wire; And (D) a first stage heat treatment of the secondary aluminum alloy wire at a temperature of 250 to 350 ° C. for 15 to 30 hours and a second heat treatment at a temperature of 300 to 450 ° C. for 50 to 80 hours. It characterized in that it comprises a step.

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Preferably, the aluminum alloy wire has a room temperature conductivity of 60% IACS or more, a normal temperature tensile strength of 16.22Kgf / mm 2 or more, and a heat resistance temperature of 230 ° C.

The present invention also provides an aluminum alloy wire with high conductivity and high heat resistance produced by the above-described manufacturing method, and a overhead transmission line having the alloy wire.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

The raw material of the aluminum alloy wire according to the present invention is produced by using aluminum as a main raw material and zirconium, iron and silicon as additive raw materials.

The zirconium has a characteristic of the symbol Zr, atomic number 40, atomic weight 91.22, specific gravity 6.51 and melting point 1,850 ° C as a transition element, and is preferably contained in an amount of 0.2 to 0.4% based on the total weight of the aluminum alloy. In this case, the heat resistance and ductility are reduced as it goes out of the content range of the zirconium, so the content range is optimal.

In addition, the zirconium serves to refine the grains of the aluminum alloy to improve elongation, and the zirconium particles formed during dissolution provide nucleation sites of aluminum during the solidification process.

The iron has a characteristic of the symbol Fe, atomic number 26, atomic weight 55.847, specific gravity 7.86, melting point 1540 ℃ and boiling point 2750 ℃ as a transition element, it is preferably included in an amount of 0.05 to 0.2% of the total weight of the aluminum alloy. In this case, since the corrosion resistance and the tensile strength decrease as it goes out of the iron content range, the content range is optimal.

In addition, the iron is a factor that controls the growth of precipitates generated in the aluminum matrix (Matrix) so that the grain (Grain) in the aluminum matrix is grown rapidly so that the ductility is not lowered.

The silicon has a characteristic of a symbol Si, atomic number 14, atomic weight 28.086, specific gravity 2.32, melting point 1410 ° C and boiling point 2335 ° C as a nonmetallic element, and is preferably contained in an amount of 0.05 to 0.2% relative to the total weight of the aluminum alloy. In this case, the heat resistance and the tensile strength are reduced as it goes out of the content range of the silicon, so the content range is optimal.

In addition, the silicon serves to increase the flow rate of the molten metal during casting of the aluminum alloy, and serves as a nucleus of precipitates generated in the aluminum matrix during precipitation hardening.

At this time, if the iron content is extremely low compared to the silicon content, the crystal grains formed in the aluminum matrix grows rapidly to reduce the ductility of the aluminum alloy. In addition, if the iron content is extremely large compared to the silicon content, the dispersion ratio of silicon atoms in the aluminum matrix is reduced to improve the heat resistance, so the sum of the components of the iron and silicon alloy elements is 0.3% of the total weight of the aluminum alloy. It is preferred not to exceed.

A manufacturing process of an aluminum alloy wire having high conductivity and high heat resistance according to a preferred embodiment of the present invention manufactured from the raw materials as described above will be described with reference to FIG. 2.

Referring to FIG. 2, first, a raw material of an aluminum alloy wire is injected and cast in a molten state at a temperature range of 750 to 900 ° C., and a cast aluminum alloy wire is rolled and extruded at a temperature range of 450 to 550 ° C. (Wire Rod) Forming (S100), and hot-rolling the cross-sectional reduction rate of the cast aluminum alloy to 70% or more to form a primary aluminum alloy wire (S200).

Here, the raw material comprises 0.2 to 0.4% by weight of zirconium, 0.05 to 0.2% by weight of iron, 0.05 to 0.2% by weight of silicon, the remainder is made of aluminum, the iron and silicon The sum of the components does not exceed 0.3% by weight.

In addition, the injection temperature range of the molten metal is to obtain a solid solution that is an intermetallic compound, that is, a casting having a dense microstructure. When the injection temperature of the molten metal exceeds 900 ° C., the microstructure of the molten metal becomes coarse, so that the impact toughness There is no improvement effect, and the temperature range of 750 to 900 ° C. is optimal because a lack of fluidity of the molten metal results in a miss run phenomenon that does not fill the mold space densely.

In addition, the rolling and extrusion temperature range is to facilitate the processing of the casting and to suppress the phase change and grain growth of the intermetallic compound in the aluminum matrix, and when the rolling and extrusion temperature exceeds 550 ℃ when rolling and extrusion It may cause the collapse of the structure such as coarsening of grains and melting of the grain boundary, and the temperature range of 450 to 550 ℃ is optimal because the rollability and extrudability are significantly lowered below 450 ℃.

At this time, the primary aluminum alloy wire has a diameter of 9.8mm Φ, the hot working in step S200 can also be performed by continuous casting rolling processing. However, the present invention is not limited thereto.

After the step S200, cold reduction of the cross-sectional reduction rate of the primary aluminum alloy wire to 85 to 90% range to form a secondary aluminum alloy wire (S300).

Here, the cold working refines the grains formed through the steps S100 to S200 and increases the strength of the aluminum alloy.

In addition, the cold working allows the alloying elements to be dissolved in the aluminum matrix in order to satisfy the precipitation conditions described below. That is, the alloy atoms in the aluminum matrix provide a site for the nuclei of precipitation, introduce energy into the aluminum matrix, and the energy acts as a driving force for precipitation. .

Aluminum alloy wire having a conductivity improved according to the invention is due to the increase due to the precipitation of Al ₃ Zr. That is, the aluminum element and the zirconium element form a compound of Al ₃ Zr through steps S100 to S300, and the conductivity of the aluminum alloy wire is improved by uniform precipitation of Al ₃ Zr.

Therefore, limiting the reduction ratio of the cross section of the step S300 to 85 to 90% is to maximize the amount of precipitation of the Al ₃ Zr in the heat treatment to be described later, maximizing the amount of precipitation of the Al ₃ Zr according to the present invention. This is to increase the electrical conductivity of the aluminum alloy wire.

And a two-stage aging process including a secondary heat treatment to optimize the deposition rate of the Al ₃ Zr nucleation primary heat treatment and the Al ₃ Zr propagating a distribution of the potential sites for the subsequent step S300 (S400).

The primary heat treatment is realized by maintaining the secondary aluminum alloy wire of the step S300 at a temperature of 250 to 350 ℃ for 15 to 30 hours, the temperature and time is the nucleus of precipitation introduced by the cold working of the step S300 It is an optimal range to further increase the production site so that a large amount of precipitates can be produced in proportion to this.

At this time, Al ₃ Zr escapes and precipitates between grain boundaries in the aluminum matrix, and a path through which a force is transmitted in the aluminum matrix is transmitted between the grain boundaries, and a precipitate is formed at the grain boundaries. Therefore, the transmission of force is hindered and the hardness increases.

The second heat treatment is realized by maintaining the first heat treated aluminum alloy wire at a temperature of 300 to 450 ° C. for 50 to 80 hours, and optimizes the amount of precipitated Al ₃ Zr deposited through the first heat treatment.

In this case, the Al is smaller amount of ₃ Zr precipitates can not improve heat resistance, because in the precipitation high, the cooling stage the amount of the Al ₃ Zr crystals of the Al ₃ Zr large, this does not evenly distributed heat resistance lowered into the aluminum matrix, Secondary heat treatment is performed within the above temperature and time ranges so that the precipitated Al ₃ Zr may be uniformly dispersed in the aluminum matrix by optimizing the particles (Particulate).

The aluminum alloy wire manufactured according to the present invention improves electrical conductivity by optimizing and depositing alloy elements in the aluminum matrix through the manufacturing process, in particular, S300 to S400. In addition, when the temperature of the conductor rises, the precipitate in the aluminum matrix inhibits the recrystallization by interfering with the movement of the crystal grains constituting the aluminum alloy wire. Improve heat resistance

In order to measure the characteristics of the aluminum alloy wire manufactured according to the above-described process, zirconium, silicon and iron were added to 99.8 wt.% Pure aluminum as an alloying element in the above-described component ratios, and then melted. Made in form. After the aluminum alloy wire was made through the steps S300 to S400. (Examples 1, 2, 3, 4).

The comparative example was manufactured by the method of Unexamined-Japanese-Patent No. 5-70,905.

Then, the electrical conductivity of the aluminum alloy wires of the Examples and Comparative Examples was measured by the Calvin Double Bridge method to obtain electrical conductivity, and mechanical properties were measured through a tensile test. In addition, in the heat resistance test for determining the heat resistance temperature, the alloy wire was heat treated at 400 ° C. for 4 hours, and the heat resistance was measured by the ratio of tensile strength before and after the heat treatment. In this case, if the heat resistance is 90% or more, it is recognized that the heat resistance temperature is 230 ° C.

The results according to the measurement are shown in Table 1 below.

Classification No. Cold working rate% Primary heat treatment Secondary heat treatment % IACS Tensile Strength Kgf / ㎡ Heat resistance% Temperature (℃) Time (H) Temperature (℃) Time (H) Example One 90 280 30 350 80 60.2 16.7 96.5 2 90 250 20 380 70 60.8 16.5 98.9 3 90 250 30 380 80 60.9 16.6 98.7 4 90 280 30 370 70 60.2 16.5 96.9

Comparative example One 58.4 16.7 95.2 2 58.7 16.8 94.6 3 58.5 16.4 93.5

As can be seen through Table 1, Examples Nos. 1 to 5 are all at room temperature conductivity of 60% IACS or more, at room temperature tensile strength of 16.22Kgf / mm2 or more, and heat resistance after heat treatment at 400 ° C. for 4 hours, 90%. As described above, it can be seen that the required characteristics of the 60% IACS-class XTAL are satisfied.

The aluminum alloy wire manufactured according to the present invention has a conductivity of 60% IACS or more, heat resistance of 90% or more, that is, continuous use temperature of 230 ° C or more, so that the steel tower or pole is supported and fixed to insulators. It can be applied to overhead transmission lines hypothesized in.

3A to 3C are schematic cross-sectional views of overhead transmission lines using aluminum alloy wires having high conductivity and high heat resistance according to an exemplary embodiment of the present invention.

3A to 3C, the overhead transmission lines 1, 2, and 3 have a stranded wire or an invar wire as core wires 1a, 2a, and 3a, and aluminum alloy wires 1b, 2b, and 3b around the core wires. Concentric twisted wire structure is intertwined.

The overhead power transmission lines 1, 2, and 3 include aluminum alloy wires 1b, 2b, and 3b having a conductivity of 60% IACS or higher and a continuous use temperature of 230 ° C or higher, thereby improving conductivity and heat resistance to generate heat. It is possible to increase the transmission capacity without loss of strength due to

As mentioned above, although this invention was demonstrated by the limited embodiment and drawing, this invention is not limited by this and is within the equal range of a common technical idea in the technical field to which this invention belongs, and a claim described below. Of course, various modifications and variations are possible.

The aluminum alloy wire manufactured according to the method of the present invention has excellent electrical conductivity and continuous use temperature characteristics compared to the conventional aluminum alloy wire, and does not add beryllium to the aluminum alloy, thereby satisfying environmental and economic aspects. The simplification of the process makes the product more productive and productive.

In addition, when the alloy wire according to the present invention is applied to the overhead transmission line, the electrical conductivity is 60% IACs or more, there is an advantage that can further increase the transmission capacity.

Claims (8)

As a method for producing an Al-Zr-Fe-Si-based aluminum alloy wire, 0.2 to 0.4% by weight of zirconium, 0.05 to 0.2% by weight of iron, and 0.05 to 0.2% by weight of silicon are added components, and the sum of the components of the iron and silicon does not exceed 0.3% by weight, and aluminum is mainly used. Raw materials made with ingredients, (A) a casting step of injecting in the state of the molten alloy in the temperature range of 750 ℃ to 950 ℃, starting rolling and extrusion in the temperature range of 450 to 550 ℃ to form a cast aluminum alloy wire; (B) a hot working step of firstly reducing the cross-section of the cast aluminum alloy wire with a cross-sectional reduction rate of 70% or more in a temperature range that suppresses phase change and grain growth of the cast aluminum alloy wire to form a primary aluminum alloy wire; (C) cold working step of secondly reducing the cross-section of the primary aluminum alloy wire to a cross-sectional reduction rate of 85 to 90% in the temperature range that can form the precipitation nucleus of the aluminum alloy to process the secondary aluminum alloy wire; And (D) a two-stage aging treatment step of subjecting the secondary aluminum alloy wire to a first heat treatment at a temperature of 250 to 350 ° C. for 15 to 30 hours and a second heat treatment at a temperature of 300 to 450 ° C. for 50 to 80 hours. A method for producing an aluminum alloy wire having high conductivity and high heat resistance, characterized in that it comprises a. delete delete delete delete The method of claim 1, The aluminum alloy wire has a high temperature conductivity of 60% IACS or higher, a normal tensile strength of 16.22Kgf / mm 2 or more, and a heat resistance temperature of 230 ° C. Aluminum alloy wire with high conductivity and high heat resistance prepared according to the method of claim 1 or 6. The overhead transmission line comprising the aluminum alloy wire of claim 7.

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