KR100755130B1 - 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, the sum of the components of the iron and silicon does not exceed 0.3% by weight, and the raw material containing aluminum as the main component is injected in the state of 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 at a temperature in the 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) a first heat treatment step of aging the primary aluminum alloy wire for 20 to 30 hours at a temperature of 350 to 400 ℃; (D) cold working step of secondly reducing the cross section of the primary heat-treated primary aluminum alloy wire to a cross-sectional reduction rate of 8 5% to 90% to process the secondary aluminum alloy wire; And (E) a secondary heat treatment step of aging the secondary aluminum alloy wire for 50 to 60 hours at a temperature lower than 20 to 30 ° C compared to the temperature of the first heat treatment.

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 aluminum alloy wire, and more particularly, to a method for simplifying a manufacturing process through primary and secondary heat treatment after hot working, and for manufacturing an aluminum alloy wire having 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 heat resistance temperature means that the change in strength does not occur even if the current of the conductor increases due to the flow of more current, and also means that the transmission capacity can be increased without the loss of strength due to 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, the conductivity and the continuous use temperature must be increased.

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. 11-92896 contains impurities containing 0.03 to 1.0% by weight of zirconium, 0.08 to 0.8% by weight of iron, 0.03 to 0.4% by weight of silicon, and 0.004 to 0.1% of titanium, with the remainder being inevitably added with aluminum. The manufacturing method of the aluminum alloy wire which consists of these is proposed.

Here, in the method of manufacturing an aluminum alloy wire according to the patent of '92896, an aluminum alloy wire having high conductivity and heat resistance was manufactured by the manufacturing process shown in FIG. 1.

Referring to Figure 1, the production of aluminum alloy wire having a conductivity of 58% or more, continuous use temperature 230 ℃ or more, the process of "casting (S10) → hot working (S20) → heat treatment (S30) → cold working (S40)" It is made through, forming a yellow phosphorus wire by continuous casting rolling (S10 to S20), and heat treatment the sulfur phosphorus for 6 to 250 hours at a temperature range of 300 to 500 ℃ to precipitate a zirconium compound ( S30). Subsequently, work is hardened through cold working to produce an aluminum alloy wire having high strength (S40). Thereafter, the aluminum alloy wire is further heat treated for 1 to 100 hours at a temperature in the range of 200 to 450 ° C., if necessary, to improve the conductivity and heat resistance of the aluminum alloy wire.

However, the manufacturing method according to the '92896 patent has a problem that the productivity decreases due to aging heat treatment for a long time, and the raw material value of titanium added to increase the high temperature strength and its processing cost are expensive, leading to an increase in production cost. .

In addition, the aluminum alloy wire produced according to the manufacturing method has a problem that the continuous use temperature is high as 230 ℃, while the conductivity is low as 58% IACS.

The present invention was devised in consideration of the above-described conventional problems, and excludes expensive titanium added to increase the strength of the aluminum alloy, and reduces the time range of heat treatment. It is an object of the present invention to provide a method for producing an aluminum alloy wire that can be increased at the same time, and an aluminum alloy wire and an overhead transmission line produced by this 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 the molten alloy into a molten state and starting rolling and extruding in a temperature range of 450 to 550 ° C. 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) a first heat treatment step of aging the primary aluminum alloy wire for 20 to 30 hours at a temperature of 350 to 400 ℃; (D) cold working step of secondly reducing the cross section of the primary heat-treated primary aluminum alloy wire to a cross-sectional reduction rate of 8 5% to 90% to process the secondary aluminum alloy wire; And (E) a secondary heat treatment step of aging the secondary aluminum alloy wire for 50 to 60 hours at a temperature lower than 20 to 30 ° C compared to the temperature of the first heat treatment.

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According to the present invention, 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 in 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 fluidity of the molten metal during casting of the aluminum alloy, and serves as a nucleus of precipitates generated in the aluminum base material 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 and thus impact toughness is increased. 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.

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 the steps S100 to S200, the conductivity of the aluminum alloy wire is improved by the uniform precipitation of the Al ₃ Zr.

After the step S200, a first heat treatment is performed to proliferate the distribution of dislocations that are nucleation sites of the Al ₃ Zr (S300). The primary heat treatment is realized by aging the primary aluminum alloy wire of the step S200 for 20 to 30 hours at a temperature of 350 to 400 ℃, the temperature and time of the precipitation introduced by the hot working of the step S200 It is an optimal range to further increase the nucleation site so that a large amount of precipitates can be produced in proportion. That is, the alloy atoms in the aluminum base material to provide a site (Site) where the nuclei of precipitation can occur, introduces energy into the aluminum base material, and the energy acts as a driving force (Driving Force) that can occur precipitation. .

Here, Al ₃ Zr exits and precipitates between grain boundaries forming the primary aluminum alloy wire by the primary heat treatment, and a path through which a force is transmitted in the primary aluminum alloy wire is It is transmitted between the grain boundaries, because precipitates are formed at the grain boundaries, which impedes the transmission of force, thereby increasing the hardness.

After the step S300, the cross-sectional reduction rate of the primary aluminum alloy wire is cold worked within a range of 85 to 90% to form a secondary aluminum alloy wire (S400).

Here, the cold working refines the grains formed through the steps S100 to S300 and increases the strength of the aluminum alloy.

In addition, the reduction of the cross-sectional reduction rate in the step S300 to 85 to 90% range is to maximize the amount of precipitation of the Al ₃ Zr in the secondary heat treatment described later, it is to maximize the amount of precipitation of the Al ₃ Zr This is to increase the electrical conductivity of the aluminum alloy wire.

After the step S400 is performed a second heat treatment to optimize the amount of precipitation of the Al ₃ Zr (S500). The secondary heat treatment is realized by aging the cold-processed secondary aluminum alloy wire for 50 to 60 hours in a temperature range of 20 to 30 ° C. lower than that of the primary heat treatment, and is precipitated through the primary heat treatment. Optimize the amount of precipitated Al ₃ Zr.

In this case, the smaller the amount of precipitation of the Al ₃ Zr can not improve the heat resistance, so at high, the cooling stage the amount of precipitation of the Al ₃ Zr crystals of the Al ₃ Zr large, this does not evenly distributed heat resistance lowered into the aluminum base material, 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 base material as particulate.

The aluminum alloy wire manufactured according to the present invention improves conductivity by optimizing and depositing alloy elements in the aluminum base material through the manufacturing process, in particular, S300 to S500. In addition, when the temperature of the conductor rises, the precipitate in the aluminum base material inhibits the recrystallization by preventing the movement of the grains constituting the aluminum alloy wire, and the existing structure does not change even at a high temperature, that is, the continuous use temperature, 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 S500 (Examples 1, 2, 3, 4 and 5).

The comparative example was manufactured by the method of Unexamined-Japanese-Patent No. 11-92896.

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 the 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. Primary heat treatment Cold working rate% Secondary heat treatment % IACS Heat resistance% Temperature (℃) Time (H) Temperature (℃) Time (H)  Example One 350 20 90 320 60 60.49 99.2 2 350 30 90 370 60 61.08 98.7 3 400 20 90 370 50 60.67 99.4 4 380 30 90 350 50 60.69 98.1 5 380 30 90 370 60 60.89 99.3 Comparative Example One - 58.00 99.6 2 - 58.00 97.0 3 - 58.20 98.2

As can be seen through Table 1, Examples Nos. 1 to 5 have a room temperature conductivity of 60% IACS or more, a room temperature tensile strength of 16.22Kgf / mm 2 or more, and a heat resistance of 90% or more. Compared with the alloy wire made of the component, the conductivity is improved, and it can be seen that the test specification of the continuous use temperature of 230 ° C is satisfied.

The aluminum alloy wire manufactured according to the present invention has a conductivity of 60% IACS or more and heat resistance of 90% or more, that is, a continuous use temperature of 230 ° C., so that a steel tower or pole is used as a support 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 titanium to the aluminum alloy, thereby reducing production costs and reducing heat treatment time. Product simplification and high productivity due to the simplified process.

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 manufacturing method of 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 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 molten alloy state of the temperature range of 750 ℃ to 950 ℃, and 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) a first heat treatment step of aging the primary aluminum alloy wire for 20 to 30 hours at a temperature of 350 to 400 ℃; (D) cold working step of secondly reducing the cross section of the primary heat-treated primary aluminum alloy wire to a cross-sectional reduction rate of 8 5% to 90% to process the secondary aluminum alloy wire; And (E) a secondary heat treatment step of aging the secondary aluminum alloy wire for 50 to 60 hours at a temperature lower than 20 to 30 ℃ compared to the temperature of the first heat treatment; high conductivity and high heat resistance Method of manufacturing an aluminum alloy wire equipped with. delete delete delete delete The method of claim 1, The aluminum alloy wire has a high temperature conductivity of 60% IACS, a normal tensile strength of 16.22 Kgf / mm 2 or more, and a continuous use 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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