WO2020232990A1 - Heat-resistant aluminum alloy having high conductivity, preparation method therefor and alloy aluminum rod used for overhead cables - Google Patents

Abstract

A preparation method for a heat-resistant aluminum alloy having high conductivity, an aluminum alloy prepared by said method, and an alloy aluminum rod used for overhead cables. The method uses continuous casting and continuous rolling for production, comprising the following steps: S1, batching the raw materials according to the following ratio: Zr 0.025-0.030％, rare earth elements 0.08-0.12％, Fe 0.10-0.15％, Si ≤0.05％, Al ≥99.65％, Ti ≤0.003％, V ≤0.003％, Cr ≤0.003％, Mn ≤0.003％, and the individual content of other impurities ≤0.03％; the rare earth elements are Ce and La, wherein the proportion of Ce ≥50％; S2, performing boronization treatment on an aluminum source, and then melting each raw material, sampling and testing to confirm whether the content of each element reaches a target value; S3, when the aluminum component reaches the target value, starting casting; and during casting, adding an aluminum-boron alloy to molten aluminum in-line; S4, performing continuous rolling on the casting blank obtained by casting, the temperature when entering rolling being controlled at 550±10°C, and the rod-receiving temperature being controlled at 250-300°C. The heat-resistant aluminum alloy prepared by using the described method has high original strength and heat-resistance, having a conductivity of up to 61.5％ IACS.

Description

High-conductivity heat-resistant aluminum alloy, preparation method thereof, and alloy aluminum rod for overhead conductor

This application claims the priority of the patent application with application number 201910412900.X filed with the State Intellectual Property Office of China on May 17, 2019, and the content of the priority text is expressly incorporated into this application by reference.

Technical field

The invention relates to the technical field of aluminum alloy materials, in particular to a high-conductivity heat-resistant aluminum alloy, a preparation method thereof, and an alloy aluminum rod for overhead conductors made of the heat-resistant aluminum alloy.

Background technique

With the rapid development of the national economy, power grid construction has been accelerated. However, the loss of electric energy has also increased. According to the survey of the electric power department, the national grid loss is more than 8.9% of the power transmitted by the power grid. The huge power loss has long made power workers realize that increasing the conductivity of aluminum and improving the transmission efficiency of the power grid Importance and urgency.

Alloy aluminum pole is the main raw material for power overhead wire transmission. It is mainly used in the production of overhead wires for power transmission lines. It can increase power transmission capacity, increase current carrying capacity, and ensure wire sag under high temperature operation. The raw material components of the existing alloy aluminum rods are: Zr: 0.03wt%, Fe: 0.12～0.2wt% and other trace elements. The processing technology is: continuous casting and rolling, batching, casting, rolling, finished products, different drawing The thread warp monofilament is filtered and degassed online during the processing to ensure the purity of the molten aluminum. The obtained alloy aluminum rod can meet the requirements of conductivity of 60% IACS and heat resistance of 150°C.

Since the conductivity of the existing alloy aluminum rod products can only achieve 60% IACS, if the conductivity can be further improved, the loss in the power transmission process can be reduced and electric energy can be saved.

Summary of the invention

The technical problem to be solved by the present invention is to provide a method for preparing a heat-resistant aluminum alloy with high conductivity, and the conductivity of the heat-resistant aluminum alloy prepared by the method can reach 61.5% IACS.

In order to solve the above technical problems, the present invention provides a method for preparing a heat-resistant aluminum alloy with high conductivity, which is produced by a continuous casting and rolling method, and includes the following steps:

S1. Prepare the raw materials according to the mass percentage of the following ingredients: Zr 0.025～0.030%, rare earth elements 0.08～0.12%, Fe 0.10～0.15%, Si≤0.05%, Al≥99.65%, Ti≤0.003%, V≤0.003 %, Cr≤0.003%, Mn≤0.003%, individual content of other impurities ≤0.03%; the rare earth elements are Ce and La, and the proportion of Ce is ≥50%;

S2. Firstly, boronize the aluminum source in the raw materials; then put the raw materials into a melting furnace to melt and stir to make the aluminum liquid uniform; then sample the aluminum liquid to confirm whether the content of each element reaches the target value; If the target value is not reached, it should be adjusted and then sampled and analyzed;

S3. When the composition of the molten aluminum reaches the target value, start casting; during the casting process, add aluminum-boron alloy to the molten aluminum online and stir to make the molten aluminum uniform; keep the casting temperature at 675-690℃;

S4. Continuously rolling the cast slab obtained by casting, the temperature of the rolling is controlled at 550±10°C, and the temperature of the rod is controlled at 250-300°C, so as to obtain the heat-resistant aluminum alloy with high conductivity.

In the present invention, the prepared aluminum liquid is processed online by adding aluminum-boron alloy online. When the aluminum liquid is cast, the second phase particles of ZrB _{2 are} precipitated, so that part of the Zr element exists in the form of solid solution in the aluminum matrix. Exist in the form of ZrB ₂ particles, thereby improving the conductivity of the alloy material.

Further, in step S1, in step S1, aluminum ingots with a purity of ≥99.70%, AlB3 alloy, AlZr ₁₀ alloy, AlRE ₁₀ alloy and AlFe ₂₀ alloy are selected as raw materials for batching.

Further, in step S2, the purpose of performing boronization treatment on the aluminum source is to reduce the content of V and Ti in the aluminum source to a target value. The boronization can be achieved by using an existing boronization process, such as adding boride to the aluminum liquid.

Further, in step S2, the melting temperature is 750-780°C.

Further, in step S2, after each raw material is melted, it also includes the step of refining the molten aluminum with a refining agent. Preferably, the refining is: using 99.999% high-purity nitrogen as a carrier, and passing a powder-sprayed refining agent into the melt in the furnace for refining.

In step S2 of the present invention, the target value refers to the mass percentage of each component in step S1.

Further, in step S3, the aluminum-boron alloy is AlB ₃ , and the addition amount of the aluminum-boron alloy is 0.8-1 kg per ton of aluminum.

Further, in step S3, while the aluminum-boron alloy is added online, the aluminum liquid is degassed and stirred by the online degassing device.

Further, in step S4, the rolling temperature is 540-560°C.

Further, in step S4, during the rolling process, an emulsion is used to lubricate and cool the roll and the aluminum rod, and the final rolling temperature of the aluminum alloy is controlled to be 250-300°C.

Another aspect of the present invention also provides a heat-resistant aluminum alloy with high conductivity prepared by the method.

In addition, the present invention also provides an alloy aluminum rod for overhead wires, which is prepared by drawing the high-conductivity heat-resistant aluminum alloy.

The beneficial effects of the present invention:

1. In the existing process, the Zr element exists in the alloy in a solid solution state. Zr is the main element to improve the heat resistance of the product. It raises the recrystallization temperature of the product and at the same time brings the negative effect of reducing the conductivity. According to the law of the influence of the element existence state in the material science on the conductivity, the element B that can form a compound with the Zr element is added online to make part of the Zr precipitate in the aluminum matrix to form ZrB ₂ second phase particles. In the case of elements, the conductivity of the alloy material is improved.

2. The present invention ensures that the aluminum material has high original strength and heat resistance by controlling the rolling temperature of the cast slab to 550±10°C.

3. The electrical conductivity of the aluminum alloy of the present invention can reach 61.5% IACS, which greatly improves the electrical conductivity of the material, and in the subsequent production of overhead wires, reduces the power loss during the transmission of electrical energy by the wires.

Detailed ways

The present invention will be further described below in conjunction with specific examples, so that those skilled in the art can better understand and implement the present invention, but the examples cited are not intended to limit the present invention.

Example 1

This embodiment provides a method for preparing a heat-resistant aluminum rod with high conductivity, and the steps are as follows:

S1. Select aluminum ingots (Al99.7), AlB ₃ alloy, AlZr ₁₀ alloy, AlRE ₁₀ alloy and AlFe ₂₀ alloy as raw materials, and prepare the raw materials according to the mass percentage of the following components: Zr 0.027%, rare earth element 0.1% (La ：0.036; Ce: 0.064), Fe 0.15%, Si 0.032%, Al 99.65%, Cr+Mn+V+Ti: 0.008%; individual content of other impurities ≤0.03%;

S2. After melting the aluminum ingot, perform boronization treatment to reduce the content of V and Ti to the target value; then add the raw materials into the melting furnace, melt the raw materials at 760°C, stir fully to make the aluminum liquid uniform; then use 99.999% The high-purity nitrogen is used as the carrier, and the powder-sprayed refining agent is passed into the melt in the furnace for refining, degassing and slagging; then samples are taken from the molten aluminum, and the content of each component in the molten aluminum is detected by a direct reading spectrometer to confirm each element Whether the content reaches the target value; if it does not reach the target value, it should be adjusted and then sampled and analyzed;

S3. When the composition of the molten aluminum reaches the target value, start casting the molten aluminum; during the casting process, the aluminum-boron alloy AlB _{3 is} added to the molten aluminum in an amount of 0.8kg per ton of aluminum, and the molten aluminum is fully stirred online; While adding the aluminum-boron alloy, the aluminum liquid is degassed and stirred through the online degassing equipment; the casting temperature is maintained at 675～690℃;

S4. Continuously rolling the cast slab obtained by casting. The temperature of the rolling is controlled to be 550～560℃. The rolling process uses emulsion to lubricate and cool the rolls and aluminum rods, so that the final rolling temperature of the aluminum material is controlled at 250 ～280℃;

S5. The aluminum material obtained after rolling is drawn into an aluminum rod with a wire diameter of 9.5 mm.

Table 1 shows the performance parameters of the aluminum rods prepared by the traditional process and the process of Example 1. It can be seen from the table that the conductivity of the aluminum rods prepared by the process of Example 1 exceeds 61.5% IACS, and the tensile strength and residual strength The other parameters are not lower than the aluminum rod prepared by traditional technology. The aluminum rod is used as a wire for power transmission, which can greatly save the loss generated during power transmission.

Table 1 Performance parameters of aluminum rods prepared by the traditional process and the process of Example 1

Example 2

This embodiment provides a method for preparing a heat-resistant aluminum rod with high conductivity, and the steps are as follows:

S1. Select aluminum ingots (Al99.8), AlB ₃ alloy, AlZr ₁₀ alloy, AlRE ₁₀ alloy and AlFe ₂₀ alloy as raw materials, and prepare the raw materials according to the mass percentage of the following components: Zr 0.030%, rare earth elements 0.08% (La ：0.025, Ce: 0.055), Fe 0.11%, Si 0.036%, Al≥99.72%, individual content of other impurities≤0.03%; Cr: 0.0012%, Mn: 0.0035%, V: 0.0015%, Ti: not detected;

S2. The aluminum ingot is melted and then boronized. The purity of the processed aluminum liquid is Al: 99.8%, Ti+Mn+Cr+V: 0.008%; then the raw materials are added to the melting furnace and melted at 780°C. The raw materials are fully stirred to make the aluminum liquid uniform; then 99.999% high-purity nitrogen is used as the carrier, and the powder-sprayed refining agent is passed into the furnace melt for refining, degassing and slagging; then sampling from the aluminum liquid, using direct reading The spectrometer detects the content of each component in the aluminum liquid to confirm whether the content of each element reaches the target value; if it does not reach the target value, it should be adjusted and then sampled and analyzed;

S3. When the composition of the molten aluminum reaches the target value, start to cast the molten aluminum; during the casting process, add the aluminum-boron alloy AlB ₃ to the molten aluminum in an amount of 1kg per ton of aluminum, and fully stir the molten aluminum; While the aluminum-boron alloy is being used, the aluminum liquid is degassed and stirred through the online degassing equipment; the casting temperature is maintained at 675-690℃;

S4. Continuously rolling the cast slab obtained by casting. The temperature of entering the rolling is controlled at 550～560℃. The rolling process uses emulsion to lubricate and cool the rolls and aluminum rods, so that the final rolling temperature of the aluminum material is 280～300 ℃;

S5. The aluminum material obtained after rolling is drawn into an aluminum rod with a wire diameter of 9.5 mm.

Table 2 shows the performance parameters of the aluminum rod prepared by the process of Example 2. It can be seen that its conductivity can reach 61.5% IACS. As a wire for power transmission, it can greatly save the loss generated during power transmission.

Table 2 Performance parameters of aluminum rods prepared by the process of Example 2

The above-mentioned embodiments are only preferred embodiments for fully explaining the present invention, and the protection scope of the present invention is not limited thereto. The equivalent substitutions or changes made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.

Claims (10)

1. A method for preparing a heat-resistant aluminum alloy with high conductivity, which is characterized in that it is produced by a continuous casting and rolling method, and includes the following steps:

   S1. Prepare the raw materials according to the mass percentage of the following ingredients: Zr 0.025～0.030%, rare earth elements 0.08～0.12%, Fe 0.10～0.15%, Si≤0.05%, Al≥99.65%, Ti≤0.003%, V≤0.003 %, Cr≤0.003%, Mn≤0.003%, individual content of other impurities ≤0.03%; the rare earth elements are Ce and La, and the proportion of Ce is ≥50%;

   S2. Firstly, boronize the aluminum source in the raw materials; then put the raw materials into a melting furnace to melt and stir to make the aluminum liquid uniform; then sample the aluminum liquid to confirm whether the content of each element reaches the target value; If the target value is not reached, it should be adjusted and then sampled and analyzed;

   S3. When the composition of the molten aluminum reaches the target value, start casting; during the casting process, add aluminum-boron alloy to the molten aluminum online and stir to make the molten aluminum uniform; keep the casting temperature at 675-690℃;

   S4. Continuously rolling the cast slab obtained by casting, the temperature of the rolling is controlled at 550±10°C, and the temperature of the rod is controlled at 250-300°C, so as to obtain the heat-resistant aluminum alloy with high conductivity.
2. The method for preparing a heat-resistant aluminum alloy with high conductivity according to claim 1, wherein in step S1, aluminum ingots with a purity of ≥99.70%, AlB ₃ alloy, AlZr ₁₀ alloy, AlRE ₁₀ alloy, and AlFe ₂₀ alloy are selected. Ingredients for raw materials.
3. The method for preparing a high-conductivity heat-resistant aluminum alloy according to claim 1, wherein, in step S2, the melting temperature is 750-780°C.
4. The method for preparing a high-conductivity heat-resistant aluminum alloy according to claim 1, wherein, in step S2, after each raw material is melted, it further comprises a step of refining the molten aluminum with a refining agent.
5. The method for preparing a high-conductivity heat-resistant aluminum alloy according to claim 1, wherein, in step S3, the aluminum-boron alloy is AlB ₃ , and the addition amount of the aluminum-boron alloy is: 0.8-1.0 per ton of aluminum kg.
6. The method for preparing a heat-resistant aluminum alloy with high conductivity according to claim 1, wherein in step S3, while adding the aluminum-boron alloy online, the aluminum liquid is degassed and stirred by the online degassing device.
7. The method for preparing a heat-resistant aluminum alloy with high conductivity according to claim 1, wherein in step S4, the rolling temperature is 540-560°C.
8. The method for preparing a heat-resistant aluminum alloy with high conductivity according to claim 1, wherein in step S4, the rolling process uses emulsion to lubricate and cool the rolls and aluminum rods, and control the final rolling temperature of the aluminum alloy to 250～300℃.
9. The high-conductivity heat-resistant aluminum alloy prepared by the method of any one of claims 1-8.
10. An alloy aluminum rod for overhead conductors, which is characterized in that it is prepared by drawing the high-conductivity heat-resistant aluminum alloy according to claim 9.