阅读说明：本技术 架空导线用高导电率耐热铝合金单丝及其制备方法 (High-conductivity heat-resistant aluminum alloy monofilament for overhead conductor and preparation method thereof ) 是由 胡博 杨长龙 许超 孙建锋 祝志祥 李希元 段昊 刘东延 李小兰 杨祖民 陈保安 于 2020-05-26 设计创作，主要内容包括：本发明公开了一种架空导线用高导电率耐热铝合金单丝及其制备方法,其中,所述架空导线用高导电率耐热铝合金单丝按重量百分比计,包括如下组分：B：0.001～0.02％,Zr：0.005～0.04％,Cu：0.001～0.05％,La：0.001～0.10％,Si：0.001～0.06％,Fe：0.001～0.12％,(V+Ti+Cr+Mn)≤0.0085％,余量为铝和不可避免的微量杂质,配合本发明的制备方法制备的铝合金单丝导电率≥61.0％IACS,抗拉强度≥180MPa,延伸率＞2.3％,耐热温度≥150℃(230℃加热1h后强度残余率大于90％)。(The invention discloses a high-conductivity heat-resistant aluminum alloy monofilament for an overhead conductor and a preparation method thereof, wherein the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor comprises the following components in percentage by weight: b: 0.001-0.02%, Zr: 0.005-0.04%, Cu: 0.001-0.05%, La: 0.001-0.10%, Si: 0.001-0.06%, Fe: 0.001-0.12%, (V + Ti + Cr + Mn) is less than or equal to 0.0085%, and the balance is aluminum and inevitable trace impurities, the conductivity of the aluminum alloy monofilament prepared by the preparation method is more than or equal to 61.0% IACS, the tensile strength is more than or equal to 180MPa, the elongation is more than 2.3%, and the heat-resistant temperature is more than or equal to 150 ℃ (the strength residual rate is more than 90% after heating at 230 ℃ for 1 h).)

1. The high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor is characterized in that: the paint comprises the following components in percentage by weight:

b: 0.001-0.02%, Zr: 0.005-0.04%, Cu: 0.001-0.05%, La: 0.001-0.10%, Si: 0.001-0.06%, Fe: 0.001-0.12%, (V + Ti + Cr + Mn) is less than or equal to 0.0085%, and the balance is aluminum and inevitable trace impurities.

2. The preparation method of the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor is characterized by comprising the following steps of:

1) smelting: adding the following components into an industrial pure aluminum melt at 740-760 ℃ to ensure that the final contents are as follows:

b: 0.001-0.02%, Zr: 0.005-0.04%, Cu: 0.001-0.05%, La: 0.001-0.10%, Si: 0.001-0.06%, Fe: 0.001-0.12%, (V + Ti + Cr + Mn) is less than or equal to 0.0085%, and the balance is aluminum and inevitable trace impurities;

2) refining: adding a refining agent into the molten aluminum at the temperature of 720-740 ℃, removing hydrogen, removing slag, refining, standing, and removing slag to obtain an aluminum alloy liquid;

3) casting: pouring the aluminum liquid prepared in the step 2) into a red copper casting mold at 700-720 ℃ to prepare an aluminum alloy ingot;

4) rod making: rolling the aluminum alloy ingot prepared in the step 3) into an aluminum alloy round rod;

5) drawing: and (3) drawing the aluminum alloy round rod prepared in the step (4) by using a drawing machine, controlling the drawing temperature to be 30-50 ℃, and preparing the aluminum alloy monofilament with the diameter of 3.0-3.6 mm.

3. The method for preparing the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor according to claim 2, which is characterized in that: in the step 1), the method also comprises the step of stirring the aluminum liquid by using an electromagnetic stirrer to fully homogenize the alloy elements.

4. The method for preparing the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor according to claim 2, which is characterized in that: in the step 1), after an industrial pure aluminum ingot is melted, adding an Al-B intermediate alloy at 740-760 ℃, standing, slagging off, heating to 760 ℃, and adding an Al-Zr alloy, an Al-Cu alloy and an Al-La alloy.

5. The method for preparing the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor according to claim 4, which is characterized by comprising the following steps of: in the step 1), adding Al-B intermediate alloy at 740-760 ℃, standing for 30min, and slagging off.

6. The method for preparing the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor according to claim 2, which is characterized in that: in the step 2), the standing time is 30 min.

7. The method for preparing the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor according to claim 2, which is characterized in that: in the step 3), the size of the aluminum alloy ingot produced is 25X 400 mm.

8. The method for preparing the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor according to claim 2, which is characterized in that: in the step 4), the aluminum alloy ingot prepared in the step 3) is subjected to heat preservation at 450-500 ℃ for 1-2 hours and then rolled into an aluminum alloy round rod.

9. The method for preparing the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor according to claim 2, which is characterized in that: in the step 4), the diameter of the aluminum alloy round rod is 9.5 mm.

10. The method for preparing the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor according to claim 2, which is characterized in that: in the step 5), the wire drawing machine performs wire drawing at the speed of 10-12 m/s and the deformation of 8-10%.

Technical Field

The invention belongs to the technical field of overhead conductors of power transmission lines in the power industry, and relates to a high-conductivity heat-resistant aluminum alloy monofilament for overhead conductors, which has the conductivity of more than or equal to 61.0% IACS, the tensile strength of more than or equal to 180MPa, the elongation of more than 2.3% and the heat-resistant temperature of more than or equal to 150 ℃ (the strength residual rate of more than 90% after heating at 230 ℃ for 1 h), and a preparation method thereof.

Background

In order to relieve the problem of serious unbalance of power resources and power load distribution, the country starts heavy power transmission projects such as extra-high voltage and the like in succession, and as the transmission capacity and distance are increased, the transmission line develops towards high capacity and high efficiency, and increasingly higher requirements are provided for service performances such as mechanical and electrical properties, heat resistance and the like of the aluminum alloy transmission conductor material. The conductivity of the common steel-cored aluminum strand is about 61% IACS, and the continuous operation temperature is about 70 ℃. The conductivity of the active heat-resistant aluminum alloy wire is 60% IACS, the continuous operation temperature can reach more than 120 ℃, the heat resistance is good, the current carrying capacity is high, the wire can operate at high temperature and high load for a long time, and the wire has more applications in high-voltage transmission lines with narrow corridors and line capacity-increasing transformation projects, and becomes an effective way for improving the line transmission capacity and saving the construction cost. Compared with the foreign countries, the heat-resistant aluminum alloy material adopted by the domestic heat-resistant aluminum alloy lead has the conductivity of less than or equal to 60% IACS (International Annealing Copper Standard) at 20 ℃, the transmission line loss is higher, and the electrical aluminum raw material with higher purity is mostly adopted for production during manufacturing, meanwhile, rare earth elements such as Er, Y and Sc with high price are generally added for microalloying modification, the production and use cost is higher, and the large-scale development and application of the lead are restricted to a certain extent.

Since Harrington discovered that Zr can be added into aluminum material to improve the heat resistance of aluminum material in 1949, researchers at home and abroad have conducted a great deal of research on heat-resistant aluminum alloy wires. Internationally, heat-resistant aluminum alloy wires have been widely used in countries such as japan, the united states, and canada by the end of the 20 th century. The development of heat-resistant aluminum alloy wires of companies such as Japan gule river, Sumitomo, Weishijia and the like is in the world leading level, the electric conductivity is 55-60% IACS, the long-term use temperature of the wires is increased to 150-230 ℃, but the electric conductivity is obviously reduced along with the increase of the heat-resistant temperature, and the loss of transmission lines is further increased. The manufacturing process of the domestic high-conductivity heat-resistant aluminum alloy conductor is similar to that of a common conductor, related cable manufacturers take a heat-resistant aluminum alloy rod as a raw material for drawing and stranding production, equipment and technology are not obviously different, the conductivity of the heat-resistant aluminum alloy conductor product is mainly 60% IACS, is 1% lower than that of a common aluminum-cored steel strand 61% IACS, and in addition, the problem of higher line loss is more and more emphasized by the power department when the heat-resistant aluminum alloy conductor is applied and popularized.

Therefore, how to improve the conductivity of the heat-resistant aluminum alloy, reduce the line loss and effectively control the cost becomes a key technical problem to be solved urgently in the current heat-resistant aluminum alloy wire on the premise of ensuring higher current-carrying capacity.

Disclosure of Invention

In view of the above, the invention aims to provide a high-conductivity and high-strength heat-resistant aluminum alloy monofilament material for overhead conductors in the power industry, and solves the problems of low conductivity, large transmission line loss, low tensile strength, low safety margin and high preparation cost of the conventional 60% IACS heat-resistant aluminum alloy conductor. Mainly adopts the control of the content of B, Zr, Cu and La microalloying elements to develop the heat-resistant aluminum alloy monofilament with the conductivity of more than or equal to 61.0 percent IACS (20 ℃), the tensile strength of more than or equal to 180MPa, the elongation of more than 2.3 percent and the heat-resistant temperature of more than or equal to 150 ℃ (the strength residual rate of more than 90 percent after heating for 1h at 230 ℃).

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a high-conductivity heat-resistant aluminum alloy monofilament for an overhead conductor, which comprises the following components in percentage by weight:

b: 0.001-0.02%, Zr: 0.005-0.04%, Cu: 0.001-0.05%, La: 0.001-0.10%, Si: 0.001-0.06%, Fe: 0.001-0.12%, (V + Ti + Cr + Mn) is less than or equal to 0.0085%, and the balance is aluminum and inevitable trace impurities.

The invention also provides a preparation method of the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor, which comprises the following steps:

1) smelting: adding the following components into an industrial pure aluminum melt at 740-760 ℃ to ensure that the final contents are as follows:

b: 0.001-0.02%, Zr: 0.005-0.04%, Cu: 0.001-0.05%, La: 0.001-0.10%, Si: 0.001-0.06%, Fe: 0.001-0.12%, (V + Ti + Cr + Mn) is less than or equal to 0.0085%, and the balance is aluminum and inevitable trace impurities;

2) refining: adding a refining agent into the molten aluminum at the temperature of 720-740 ℃, removing hydrogen, removing slag, refining, standing, and removing slag to obtain an aluminum alloy liquid;

3) casting: pouring the aluminum liquid prepared in the step 2) into a red copper casting mold at 700-720 ℃ to prepare an aluminum alloy ingot;

4) rod making: rolling the aluminum alloy ingot prepared in the step 3) into an aluminum alloy round rod;

5) drawing: and (3) drawing the aluminum alloy round rod prepared in the step (4) by using a drawing machine, controlling the drawing temperature to be 30-50 ℃, and preparing the aluminum alloy monofilament with the diameter of 3.0-3.6 mm.

Preferably, the step 1) further comprises the step of stirring the aluminum liquid by using an electromagnetic stirrer to fully homogenize the alloy elements.

Further preferably, in the step 1), after the industrial pure aluminum ingot is melted, adding an Al-B intermediate alloy at 740-760 ℃, standing, slagging off, heating to 760 ℃, and adding an Al-Zr alloy, an Al-Cu alloy and an Al-La alloy, wherein the standing time is preferably 30 min.

More preferably, in the step 2), the standing time is 30 min.

Further preferably, in the step 3), the size of the aluminum alloy ingot produced is 25X 400 mm.

Further preferably, in the step 4), the aluminum alloy ingot prepared in the step 3) is kept at 450-500 ℃ for 1-2 hours and then rolled into an aluminum alloy round rod, and preferably 1 hour.

More preferably, in the step 4), the diameter of the aluminum alloy round rod is 9.5 mm.

More preferably, in the step 5), the wire drawing machine performs wire drawing at a speed of 10-12 m/s and a deformation of 8-10%.

The invention provides a high-conductivity heat-resistant aluminum alloy monofilament for an overhead conductor, which comprises Al, B, Zr, Cu, La alloy elements and main impurity elements such as Fe, Si, Cr, Mn, V, Ti and the like, and comprises the following components in percentage by weight: b: 0.001-0.02%, Zr: 0.005-0.04%, Cu: 0.001-0.05%, La: 0.001-0.10%, Si: 0.001-0.06%, Fe: 0.001-0.12%, (V + Ti + Cr + Mn) is less than or equal to 0.0085%, and the balance is aluminum and inevitable trace impurities.

Wherein the action and mechanism of each alloy element are as follows:

zr: to improve the conductivity of aluminum alloyThe heat resistance of (2) must be contrived to prevent the reduction of the distortion energy of the alloy so that the strength of the aluminum alloy is not lowered by the increase of the temperature. The addition of a proper amount of zirconium can obviously improve the heat resistance of the aluminum alloy, mainly because the atomic radius of zirconium is slightly larger than that of aluminum, zirconium 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 creep resistance of the aluminum alloy can be improved by adding zirconium, so that the aluminum alloy has small creep elongation at high temperature, the distance between overhead transmission lines and power transmission tower poles can be increased, and the smaller suspension degree of the aluminum alloy conductor can be kept.

B: if the impurity elements exist in the aluminum conductor in a solid solution state, 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 transition group impurity elements such as Cr, Mn, V, Ti and the like, so that the B element is converted from the solid solution state to the compound state and is deposited at the bottom of a melt to purify the aluminum conductor, thereby improving the conductivity of the aluminum alloy. 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 the Zr-containing aluminum alloy, but the excessive addition of B can cause the alloy to have strong high temperatureThe degree decreases, and the heat resistance of the alloy deteriorates.

Cu: copper is an important alloy element, has certain solid solution strengthening effect and CuAl precipitated by aging₂Has obvious aging strengthening effect. The high temperature strength and the machinability can be improved by solid-dissolving a proper amount of Cu element in the aluminum alloy, but the addition of excessive Cu element causes larger lattice distortion, increases the scattering of free electrons, and causes the reduction of the electrical conductivity of the aluminum alloy. Therefore, the addition of a proper amount of copper element can achieve a better strengthening effect on the premise of ensuring the conductivity of the aluminum alloy.

La: the rare earth element La is added into the aluminum alloy, so that the super-cooling of the components is increased during the casting of the aluminum alloy, the crystal grains are refined, the secondary crystal spacing is reduced, the gas and impurities in the aluminum alloy are reduced, the impurity phase tends to be spheroidized, the surface tension of a melt can be reduced, the fluidity is increased, the ingot casting is facilitated, and the technological performance of the aluminum alloy is improved.

Si: silicon is mainly derived from silicon dioxide or silicate in bauxite and is one of the main impurity elements 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 mainly because Si is a semiconductor and has a much higher resistivity than the aluminum matrix, so increasing the 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 a major impurity in pure aluminum. Since tools used for melting and casting are mainly made of steel or cast iron, Fe elements are carried into aluminum by these tools, and iron and scrap iron may be mixed in the remelting of scrap. 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. Recent studies have shown that iron can increase the strength of aluminum conductors without significantly reducing their electrical conductivity. However, it is also known that in practical production, the Fe/Si ratio of the aluminum conductor should be 1.3-1.5, and too high a ratio will significantly increase the resistivity, so that care should be taken to control the iron content.

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. Studies have shown that the detrimental effect per 1% (Cr + Mn + V + Ti) is 5 times the detrimental effect per 1% Si on the conductivity of aluminum conductors. Therefore, 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 conductor.

The heat-resistant aluminum alloy monofilament provided by the invention has the conductivity of more than or equal to 61.0% IACS, the tensile strength of more than or equal to 180MPa, the elongation of more than 2.3%, and the heat-resistant temperature of more than or equal to 150 ℃ (the strength residual rate of more than 90% after heating at 230 ℃ for 1 h).

According to the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor, trace elements B, Zr, Cu and La are added into the aluminum alloy, so that the impurity content of the aluminum alloy can be reduced, a high-temperature strengthening phase can be formed, the heat stability and the high-temperature strength of the aluminum alloy are improved, and the aluminum alloy material is guaranteed to have high conductivity and good mechanical property and heat resistance.

The preparation method of the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor provided by the invention comprises the steps of smelting, adding B, Zr, Cu and La components after an industrial pure aluminum ingot is completely melted, and controlling the alloying temperature to be 740-760 ℃; carrying out dehydrogenation and deslagging refining on the aluminum liquid by adopting a refining agent, carrying out slagging-off and aluminum alloy liquid casting after standing, and casting into an aluminum alloy ingot by adopting a red copper mold; pressing an aluminum alloy ingot into a round rod by adopting a hot rolling mode, then drawing wires, drawing the wires on a wire drawing machine at the speed of 10-12 m/s, controlling the wire drawing temperature at 30-50 ℃, and finally obtaining 3.0-3.6 mm aluminum alloy monofilaments by using a steel die through multi-pass drawing. The heat-resistant aluminum alloy monofilament material prepared by the invention does not need to carry out heat treatment on a round rod or a monofilament, so that the preparation process of the high-conductivity heat-resistant aluminum alloy monofilament material is simplified, and the production cost is reduced, therefore, the conductivity of the high-conductivity heat-resistant aluminum alloy monofilament for the overhead conductor is more than or equal to 61.0 percent IACS, the tensile strength is more than or equal to 180MPa, the elongation is more than 2.3 percent, and the heat-resistant temperature is more than or equal to 150 ℃ (the strength residual rate is more than 90 percent after heating at 230 ℃ for.

Detailed Description

The invention will be further explained with reference to specific embodiments, without limiting the invention.