High-conductivity heat-resistant aluminum alloy monofilament and preparation method thereof

文档序号：274669 发布日期：2021-11-19 浏览：11次中文

阅读说明：本技术 一种高导电率耐热铝合金单丝及制备方法 (High-conductivity heat-resistant aluminum alloy monofilament and preparation method thereof ) 是由朱元成徐中凯祝志祥陈保安丁一张强庞震杨长龙郑炜亮郑薇马洪峰于 2021-07-14 设计创作，主要内容包括：一种高导电率耐热铝合金单丝,成分组成包括Al、B、Zr、Dy、Y元素以及杂质元素Fe、Si、Cr、Mn、V、Ti,各成分组份的质量百分比为：B：0.002～0.03％,Zr：0.002～0.03％,Dy：0.005～0.05％,Y：0.005～0.03％,Si：0.001～0.06％,Fe：0.001～0.10％,(V+Ti+Cr+Mn)≤0.007％,余量为铝和不可避免的微量杂质。一种制备高导电率耐热铝合金单丝的方法,熔炼、精炼；浇铸：铝合金液经Al-(2)O-(3)泡沫陶瓷过滤装置过滤除杂后浇铸到高强度钢质模具内；制杆：将耐热铝合金锭在500～510℃保温1.5小时后,在轧机上轧制成；拉丝：拉丝温度为30～40℃,变形量为15～20％,拉丝模具为聚晶金刚石模具。本发明的优点：简化了高导电率耐热铝合金单丝材料的制备流程,导电率≥61.8％IACS,抗拉强度≥172MPa,延伸率≥2.0％,耐热温度为150℃。(A high-conductivity heat-resistant aluminum alloy monofilament comprises Al, B, Zr, Dy and Y elements and impurity elements Fe, Si, Cr, Mn, V and Ti, and comprises the following components in percentage by mass: b: 0.002-0.03%, Zr: 0.002-0.03%, Dy: 0.005 to 0.05%, Y: 0.005-0.03%, Si: 0.001-0.06%, Fe: 0.001-0.10%, (V + Ti + Cr + Mn) is less than or equal to 0.007%, and the balance is aluminum and inevitable trace impurities. A method for preparing high-conductivity heat-resistant aluminum alloy monofilament comprises smelting and refining; casting: aluminum alloy liquid Al 2 O 3 Filtering and impurity removing by a foamed ceramic filtering device, and casting into a high-strength steel mould; rod making: keeping the temperature of the heat-resistant aluminum alloy ingot at 500-510 ℃ for 1.5 hours, and then rolling the aluminum alloy ingot on a rolling mill; drawing: the wire drawing temperature is 30-40 ℃, the deformation is 15-20%, and the wire drawing die is a polycrystalline diamond die. The invention has the advantages that: the preparation process of the high-conductivity heat-resistant aluminum alloy monofilament material is simplified, the conductivity is more than or equal to 61.8 percent IACS, the tensile strength is more than or equal to 172MPa, the elongation is more than or equal to 2.0 percent, and the heat-resistant temperature is 150 ℃.)

1. A high-conductivity heat-resistant aluminum alloy monofilament is characterized in that: the high-conductivity heat-resistant aluminum alloy monofilament comprises Al, B, Zr, Dy and Y elements and impurity elements of Fe, Si, Cr, Mn, V and Ti, and comprises the following components in percentage by mass: b: 0.002-0.03%, Zr: 0.002-0.03%, Dy: 0.005-0.05%, Y: 0.005-0.03%, Si: 0.001-0.06%, Fe: 0.001-0.10 percent of aluminum, less than or equal to 0.007 percent of V, Ti, Cr and Mn, and the balance of aluminum and inevitable trace impurities.

2. The high-conductivity heat-resistant aluminum alloy monofilament as claimed in claim 1, wherein: the high-conductivity heat-resistant aluminum alloy monofilament comprises the following components in percentage by mass:

3. the high-conductivity heat-resistant aluminum alloy monofilament as claimed in claim 1, wherein: the high-conductivity heat-resistant aluminum alloy monofilament comprises the following components in percentage by mass:

4. the high-conductivity heat-resistant aluminum alloy monofilament as claimed in claim 1, wherein: the high-conductivity heat-resistant aluminum alloy monofilament comprises the following components in percentage by mass:

5. the high-conductivity heat-resistant aluminum alloy monofilament as claimed in claim 1, wherein: the high-conductivity heat-resistant aluminum alloy monofilament comprises the following components in percentage by mass:

6. the high-conductivity heat-resistant aluminum alloy monofilament as claimed in claim 1, wherein: the high-conductivity heat-resistant aluminum alloy monofilament comprises the following components in percentage by mass:

7. a method for preparing high-conductivity heat-resistant aluminum alloy monofilaments is characterized by comprising the following steps: the method comprises the following steps:

smelting: selecting an industrial pure aluminum ingot with the purity of 99.8% of Al, and putting the industrial pure aluminum ingot into a medium-frequency induction furnace for smelting, wherein the smelting temperature is 730-750 ℃; after the pure aluminum is completely melted, adding Al-B intermediate alloy at 720-730 ℃ for boronizing treatment; standing for 40 minutes, simultaneously adding Al-Zr intermediate alloy and Dy at 710-720 ℃, wherein the purity of the Al-Zr intermediate alloy and the purity of the Dy are 99.99% of metal and Y metal, and the purity of the Y metal is 99.99%, stirring the aluminum alloy liquid after complete melting, and stirring once every 15-20 minutes for 10 minutes for 3 times;

refining: introducing nitrogen at 710-720 ℃ for 15-20 minutes, adding a covering agent, standing for 30-40 minutes, and slagging off; the adding amount of the covering agent is 0.02 to 0.04 percent of the total amount of the furnace burden;

casting: subjecting the aluminum alloy liquid to Al treatment at 710-720 DEG C₂O₃Filtering and impurity removing by a foamed ceramic filtering device, and then casting into a high-strength steel mold to prepare a heat-resistant aluminum alloy ingot with the size of 30mm multiplied by 400 mm;

rod making: keeping the temperature of the heat-resistant aluminum alloy ingot at 500-510 ℃ for 1.5 hours, and then rolling the heat-resistant aluminum alloy ingot on a rolling mill into a heat-resistant aluminum alloy round rod with the diameter of 9.5 mm;

drawing: drawing a heat-resistant aluminum alloy round rod on a drawing machine at the speed of 12-15 m/s, wherein the drawing temperature is 30-40 ℃, and the deformation is 15-20%; and drawing the heat-resistant aluminum alloy round monofilament with a polycrystalline diamond wire drawing die for 14 times to finally obtain the heat-resistant aluminum alloy round monofilament with the diameter of 3.08-3.10 mm.

Technical Field

The invention relates to the technical field of wires for overhead transmission lines in the power industry, in particular to a high-conductivity heat-resistant aluminum alloy monofilament material for an overhead wire, which has the conductivity of more than or equal to 61.8 percent IACS, the tensile strength of more than or equal to 172MPa, the elongation of more than or equal to 2.0 percent and the heat-resistant temperature of 150 ℃, and particularly relates to a high-conductivity heat-resistant aluminum alloy monofilament and a preparation method thereof.

Background

Energy resources and power load distribution are seriously unbalanced, and higher requirements are provided for the technical level of high-capacity and low-loss electric energy transmission of the conductor for the overhead transmission line. With the gradual construction of the global energy internet, large-span and large-altitude-difference areas are more and more, and a large number of overhead power transmission conductors which can transmit large current and operate at higher temperature for service are urgently needed.

The conductor for the active overhead transmission line is a common aluminum steel-cored stranded wire, the conductivity of the used hard aluminum conductor material at 20 ℃ is not less than 61% IACS (International Annealing Copper Standard), but the conductor has poor heat resistance (the long-term operation temperature is generally below 90 ℃) and low current-carrying capacity. The heat-resistant aluminum alloy conductor is a capacity-increasing conductor with good performance, the transmission capacity of a line can be improved by directly replacing the heat-resistant aluminum alloy conductor under the condition of not replacing a tower, the procedures of land acquisition and tower dismantling are omitted, and the construction period is greatly shortened. For newly-built lines, the heat-resistant aluminum alloy conductor has the advantages of reducing the arrangement position of the iron towers, reducing sag, increasing the gear distance, reducing the number of the iron towers and saving power transmission corridors. In addition, the heat-resistant aluminum alloy conductor can effectively improve the short-time overload (such as N-1 fault) bearing capacity of the power transmission line, and ensure the safe and reliable operation of new energy transmitted out of the overhead power transmission line. At present, heat-resistant aluminum alloy conductor products in domestic and foreign markets are mainly heat-resistant aluminum alloy conductors with the electric conductivity of 60% IACS and the long-term operation heat-resistant temperature of 150 ℃, the electric conductivity level is 1% lower than that of a 61% IACS common steel-cored aluminum strand, the transmission loss per kilometer is increased by about 0.5-1.0 ten thousand kW hours/year, and the popularization and application of the heat-resistant aluminum alloy conductors are greatly limited. In recent years, the nanometer rare earth additive is used for doping and modifying the existing heat-resistant aluminum alloy conductor material, so that the high current-carrying capacity is ensured, the electric conductivity of the heat-resistant aluminum alloy material is further improved, the power transmission line loss is reduced, and the method becomes a hotspot for researching the existing heat-resistant aluminum alloy conductor material.

Disclosure of Invention

The invention aims to develop a high-conductivity heat-resistant aluminum alloy monofilament material for overhead transmission conductors in the power industry, and solve the technical problem that the conventional 60% IACS heat-resistant aluminum alloy conductor has low conductivity and large transmission line loss. By controlling the addition of B, Zr and Dy and Y microalloying elements, the high-conductivity heat-resistant aluminum alloy monofilament material with the electrical conductivity of more than 61.8 percent IACS (20 ℃), the tensile strength of more than or equal to 172MPa, the elongation of more than or equal to 2.0 percent, the heat-resistant temperature of 150 ℃, and the strength residual rate of more than 90 percent after heating for 1 hour at 230 ℃ is developed.

The invention provides a high-conductivity heat-resistant aluminum alloy monofilament, which comprises the following components in percentage by weight: the high-conductivity heat-resistant aluminum alloy monofilament comprises Al, B, Zr, Dy and Y elements and impurity elements of Fe, Si, Cr, Mn, V and Ti, and comprises the following components in percentage by mass: b: 0.002-0.03%, Zr: 0.002-0.03%, Dy: 0.005-0.05%, Y: 0.005-0.03%, Si: 0.001-0.06%, Fe: 0.001-0.10 percent of aluminum, less than or equal to 0.007 percent of V, Ti, Cr and Mn and the balance of aluminum and inevitable trace impurities;

the action and mechanism of each microalloying element adopted by the invention are as follows:

dy: the aluminum alloy is modified by adding trace rare earth Dy, so that the strength and the heat resistance of the aluminum alloy can be obviously improved, the dendritic crystal segregation of the aluminum alloy can be reduced,the grain structure of the aluminum alloy is refined. The refining mechanism of Dy element on crystal grains is related to the addition amount of Dy element, and when the Dy content is low, the Dy element accords with the traditional rare earth refining mechanism; when Dy content is high, primary Al is formed in the melt₃Dy particles can be used as heterogeneous nucleation cores during crystallization and nucleation, so that the grain structure is obviously refined; dy can also react with part of impurity elements Fe and Si in the aluminum alloy to convert the impurity elements from an atomic state to a precipitation state, so that the conductivity of the aluminum alloy is improved.

Y: the addition of the rare earth Y improves the conductivity of the aluminum alloy because the Y and solid-solution impurity elements Fe and Si in the aluminum have strong interaction, and a rare earth compound formed by the Y and the impurity atoms is separated out at a crystal boundary, so that the solid solubility of the impurity elements Fe and Si in a matrix is reduced. When the impurity elements exist in the aluminum in a solid solution state, the increasing effect on the resistivity of the aluminum conductor is far larger than that in a precipitation state, Fe and Si impurities and Y react to generate compounds which are precipitated at a crystal boundary, and the scattering effect of the solid solution Fe and Si on electrons is reduced, so that the conductivity of the aluminum alloy can be improved by adding a proper amount of Y. However, excessive nano Y can affect the conductivity of the aluminum alloy, and the increase of Y content can enhance the grain refinement effect and increase the scattering of electrons, thereby reducing the conductivity. Therefore, the content of Y should be controlled within a certain range to ensure the conductivity of the aluminum alloy conductor.

Zr: to improve the heat resistance of the conductive aluminum alloy, it is necessary to prevent the reduction of the alloy distortion energy so that the strength of the aluminum alloy does not decrease due to the increase in temperature. The addition of a proper amount of Zr can obviously improve the heat resistance of the aluminum alloy, and because the atomic radius of Zr is slightly larger than that of aluminum, Zr diffuses in aluminum in a replacement mode, the diffusion activation energy is high, and fine Al is precipitated to the boundary of a sub-crystal grain₃The Zr phase is not easy to aggregate and grow up, has high stability, inhibits the occurrence of recrystallization, can still effectively pin dislocation and crystal boundary at higher temperature, and blocks deformation and intragranular and crystal boundary slippage, so that the creep resistance is improved, and the heat resistance of the aluminum alloy is improved. Meanwhile, the addition of Zr can improve the creep resistance of the aluminum alloy, so that the aluminum alloy has small creep elongation at high temperature, and therefore, the aluminum alloy can be subjected to creep elongationThe spacing of the overhead transmission lines between the transmission towers is increased and a small degree of sag of the aluminum alloy conductor is maintained.

B: if the impurity elements exist in a solid solution state in the aluminum conductor, the influence on the conductivity is great, and the boronization treatment can effectively reduce the impurity content, namely after a certain amount of B element is added into the electrical aluminum, the B element can react with the impurity elements of the transition group impurity elements Cr, Mn, V and Ti to enable the impurity elements to be converted into a compound state from the solid solution state and deposited at the bottom of a melt to purify the aluminum conductor, so that the conductivity of the aluminum alloy is improved. Meanwhile, the heat resistance of the alloy can be obviously improved by adding a proper amount of Zr into the aluminum conductor, but the addition of Zr can also have adverse effect on the conductivity of the alloy. Research shows that proper amount of B is added into Zr-containing aluminum alloy to ensure the conductivity of the alloy while ensuring the heat resistance of the alloy. It is generally considered that when B is not added in excess in the alloy, that is, B added to the Zr-containing heat-resistant aluminum alloy material is controlled in a ratio of Zr: b is 1: 2, the added B forms ZrB with Zr in the alloy₂Compound ZrB due to its dispersive distribution and small particles₂Can not be used as the nucleation center of Al atoms, so that the Zr-based alloy can not generate grain refining effect on the alloy and can not increase grain boundaries, thereby reducing the negative influence of Zr element on the conductivity of the alloy. However, the excessive addition of B has a certain grain refining effect on Zr-containing aluminum alloys, but it causes the alloy to have a reduced high-temperature strength, resulting in a deteriorated alloy heat resistance.

Si: silicon is derived from silicon dioxide or silicate in bauxite and is an impurity element in pure aluminum. Si can improve the casting performance and welding fluidity of the aluminum alloy and can also enable the aluminum alloy to have higher mechanical properties. However, as the Si content increases, the resistivity of the aluminum alloy increases. This is because Si is a semiconductor and has a much higher resistivity than the aluminum matrix, so an increase in Si content will reduce the effective conductive cross-sectional area of the aluminum matrix, reducing the conductivity of the aluminum alloy. Therefore, the Si content should be minimized in order to reduce the resistivity of the duralumin material.

Fe: aluminum contains a certain amount of iron, which is an impurity in pure aluminum. Since the tools used for melting and casting are steel or cast iron, Fe elements are carried into aluminum by these tools, and iron and scrap iron may be mixed in when scrap is remelted. Iron is detrimental to the mechanical properties of cast aluminum because it usually appears as coarse primary crystals, or as Al-Fe-Si compounds, which increase the hardness of aluminum to some extent but reduce the plasticity of aluminum. Studies have shown that iron can increase the strength of aluminum conductors without significantly reducing their electrical conductivity. But not too high, which would otherwise increase the resistivity significantly, so the iron content should be strictly controlled.

Cr, Mn, V, Ti: the four elements are all impurity elements in electrician pure aluminum. If the impurity elements Cr, Mn, V, and Ti in the aluminum conductor exist in a solid solution state, they easily absorb free electrons in the conductor material and fill the incomplete electron shells. This reduction in the number of conduction electrons results in an increase in the resistivity of the aluminum conductor. Researches show that the harmful effect of every 1% (Cr + Mn + V + Ti) is 5 times of the harmful effect of every 1% Si on the conductivity of the aluminum conductor, so that the strict control of the contents of Cr, Mn, V and Ti impurity elements has an important effect on ensuring the conductivity of the aluminum alloy conductor.

The high-conductivity heat-resistant aluminum alloy monofilament material has the conductivity of more than or equal to 61.8 percent IACS, the tensile strength of more than or equal to 172MPa, the elongation of more than or equal to 2.0 percent, the heat-resistant temperature of 150 ℃, and the strength residual rate of more than 90 percent after being heated for 1 hour at 230 ℃.

A method for preparing high-conductivity heat-resistant aluminum alloy monofilaments comprises the following steps:

smelting: selecting an industrial pure aluminum ingot with the purity of 99.8% of Al, and putting the industrial pure aluminum ingot into a medium-frequency induction furnace for smelting, wherein the smelting temperature is 730-750 ℃; after the pure aluminum is completely melted, adding Al-B intermediate alloy at 720-730 ℃ for boronizing treatment; and standing for 40 minutes, simultaneously adding Al-Zr intermediate alloy, Dy (with the purity of 99.99%) metal and Y metal (with the purity of 99.99%) at 710-720 ℃, stirring the aluminum alloy liquid after complete melting, and stirring once every 15-20 minutes for 10 minutes for 3 times.

Refining: introducing nitrogen at 710-720 ℃ for 15-20 minutes, adding a covering agent, standing for 30-40 minutes, and slagging off; the adding amount of the covering agent is 0.02-0.04% of the total amount of the furnace charge.

Casting: subjecting the aluminum alloy liquid to Al treatment at 710-720 DEG C₂O₃And filtering and impurity removing by a foamed ceramic filtering device, and then casting into a high-strength steel mold to prepare a heat-resistant aluminum alloy ingot with the size of 30mm multiplied by 400 mm.

Rod making: and (3) keeping the temperature of the heat-resistant aluminum alloy ingot at 500-510 ℃ for 1.5 hours, and then rolling the heat-resistant aluminum alloy ingot on a rolling mill to obtain a heat-resistant aluminum alloy round rod with the phi of 9.5 mm.

Drawing: and (2) drawing the heat-resistant aluminum alloy round rod on a drawing machine at the speed of 12-15 m/s, wherein the drawing temperature is 30-40 ℃, and the deformation is 15-20%. And drawing the heat-resistant aluminum alloy round monofilament with a polycrystalline diamond wire drawing die for 14 times to finally obtain the heat-resistant aluminum alloy round monofilament with the diameter of 3.08-3.10 mm.

Due to the fact that trace elements B, Zr, Dy and Y are added into the aluminum alloy, the impurity content of the aluminum alloy can be reduced, the conductivity of the aluminum alloy is improved, a high-temperature strengthening phase can be formed, the thermal stability and the high-temperature creep resistance of the aluminum alloy are improved, and therefore the aluminum alloy material is guaranteed to have high conductivity and good mechanical property and heat resistance. The process is characterized in that: smelting, namely sequentially adding Al-B, Al-Zr, Dy metal and Y metal into an industrial pure aluminum ingot after the industrial pure aluminum ingot is completely molten, wherein the alloying temperature is 710-730 ℃; stirring the aluminum liquid by using a stirrer to fully homogenize alloy elements; carrying out dehydrogenation and deslagging refining on the aluminum liquid by adopting a refining agent, standing for 30-40 minutes, then carrying out deslagging, filtering and impurity removal on the aluminum alloy liquid, and casting into an aluminum alloy ingot with the thickness of 30mm multiplied by 400mm by adopting a high-strength steel mould; pressing an aluminum alloy ingot into a round rod with the phi of 9.5mm by adopting a hot rolling mode, then drawing wires, drawing wires on a wire drawing machine at the speed of 12-15 m/s, controlling the wire drawing temperature to be 30-40 ℃, and drawing the wires by using a polycrystalline diamond wire drawing die for 14 times to finally prepare the heat-resistant aluminum alloy monofilament with the thickness of 3.08-3.10 mm.

According to the preparation method of the heat-resistant aluminum alloy monofilament material, the round rod or the monofilament does not need to be subjected to heat treatment, so that the preparation process of the high-conductivity heat-resistant aluminum alloy monofilament material is simplified, and the manufacturing cost is reduced, so that the prepared heat-resistant aluminum alloy monofilament material for the overhead conductor has the conductivity of more than or equal to 61.8% IACS, the tensile strength of more than or equal to 172MPa, the elongation of more than or equal to 2.0%, the heat-resistant temperature of 150 ℃, and the strength residual rate of more than 90% after being heated at 230 ℃ for 1 hour.

The invention has the advantages that:

the preparation process of the high-conductivity heat-resistant aluminum alloy monofilament material is simplified, the manufacturing cost is reduced, the conductivity of the prepared heat-resistant aluminum alloy monofilament material for the overhead conductor is not less than 61.8 percent IACS, the tensile strength is not less than 172MPa, the elongation is not less than 2.0 percent, the heat-resistant temperature is 150 ℃, and the strength residual rate is more than 90 percent after the heat-resistant aluminum alloy monofilament material is heated for 1 hour at 230 ℃.

Detailed Description

Example 1