阅读说明：本技术 一种软铝线及其制备方法 (Soft aluminum wire and preparation method thereof ) 是由 祝志祥 赵蕊 潘学东 陈保安 张强 丁一 陈新 杨长龙 周忠义 刘臻 党朋 殷 于 2019-07-01 设计创作，主要内容包括：本发明属于软铝线的制备技术领域,具体涉及一种软铝线及其制备方法。本发明在通过硼对杂质元素进行严格净化控制的基础上,在铝合金中添加了微量Y稀土元素,既能够降低杂质含量,又具有晶粒细化以及提高结晶温度的作用,一定程度上在保证铝导体具有高导电率的同时具有良好的力学性能；所提供的软铝线材料的导电率≥63.5％IACS(20℃),抗拉强度≥75MPa,延伸率≥20.0％。(The invention belongs to the technical field of preparation of soft aluminum wires, and particularly relates to a soft aluminum wire and a preparation method thereof. According to the invention, on the basis of strict purification control of impurity elements through boron, trace Y rare earth elements are added into the aluminum alloy, so that the impurity content can be reduced, the effects of grain refinement and crystallization temperature increase are achieved, and the aluminum conductor has high conductivity and good mechanical properties to a certain extent; the conductivity of the provided soft aluminum wire material is more than or equal to 63.5 percent IACS (20 ℃), the tensile strength is more than or equal to 75MPa, and the elongation is more than or equal to 20.0 percent.)

1. The soft aluminum wire is characterized by comprising the following components in percentage by mass: 0.002-0.05%, Y: 0.001-0.10%, Si: 0-0.06%, Fe: 0-0.12 percent of the total weight of the alloy, and less than or equal to 0.01 percent of V, Ti, Cr and Mn.

2. The soft aluminum wire according to claim 1, which comprises the following components in percentage by mass, B: 0.002-0.03%, Y: 0.01 to 0.05%, Si: 0-0.05%, Fe: 0.01-0.10 percent of aluminum, less than or equal to 0.008 percent of V, Ti, Cr and Mn and the balance of aluminum and inevitable impurity elements.

3. A method for preparing a soft aluminum wire according to claim 1 or 2, comprising the steps of:

smelting: melting an aluminum ingot, adding Al-B alloy into the aluminum melt, standing, and then adding Al-Y alloy for smelting;

refining: adding a covering agent, refining in a nitrogen atmosphere, standing and slagging off;

casting: casting the aluminum alloy liquid according to a preset size to obtain an aluminum alloy ingot;

rod making: rolling the aluminum alloy ingot into an aluminum alloy rod after heat preservation;

drawing: carrying out wire drawing treatment on the aluminum alloy rod to obtain an aluminum monofilament;

annealing: and annealing the aluminum monofilament to obtain the soft aluminum wire.

4. The method as claimed in claim 3, wherein the annealing temperature is 330-380 ℃ and the annealing time is 2-5 h.

5. The method for preparing a soft aluminum wire as recited in claim 3, wherein the melting temperature is 750-770 ℃;

the standing time after the Al-B alloy is added is 20-40 min.

6. The method as claimed in claim 3, wherein the refining temperature is 730-740 ℃ and the refining time is 10-15 min.

7. The method for manufacturing a soft aluminum wire according to claim 3, wherein the standing time in the refining step is 20 to 40 min;

the addition amount of the covering agent is 0.01-0.03% of the total feeding mass.

8. The method as claimed in claim 3, wherein the casting temperature is 720-730 ℃.

9. The method for preparing a soft aluminum wire according to claim 3, wherein the temperature of the rod-making step is 400-450 ℃ and the holding time is 40-80 min.

10. The method for producing a soft aluminum wire according to claim 3, wherein the drawing speed is 13 to 16m/s and the amount of deformation is 20 to 25%.

Technical Field

The invention belongs to the technical field of preparation of soft aluminum wires, and particularly relates to a soft aluminum wire with high process stability and high conductivity qualified rate and a preparation method thereof.

Background

The rapid construction and development of the power grid in China put forward higher requirements on overhead transmission lines. How to realize the electric energy transmission with high capacity, high efficiency and low cost on the basis of ensuring the safe and reliable operation of the overhead conductor is a hot spot concerned by researchers in the power industry.

The steel-cored aluminum strand is one of the most applied conductors in overhead transmission lines, and accounts for more than 80% of the whole conductor type. The electric conductivity of the steel-cored aluminum strand is 61% IACS, and the loss of the power transmission line is higher. In order to improve the conductivity of the wire, the development of new materials, new processes and new technologies, the production of novel high-conductivity wires is promoted, and novel wires which take soft aluminum as a conductor, such as steel core soft aluminum wires, carbon fiber composite core wires and the like, are developed in sequence.

The soft aluminum conductor has higher conductivity and lower resistance in the same section, and can reduce the loss of the lead. The steel core soft aluminum conductor has been applied in countries such as the United states, Canada and the like for nearly twenty years, and a plurality of manufacturers can produce the steel core soft aluminum conductor at home. Compared with the existing domestic and overseas soft aluminum wire standards, the domestic and overseas soft aluminum wire has the main technical difference that the conductivity index is the requirement, the domestic standard (ASTM-B609/B609M-2016, BS EN 50540-.

Currently, some domestic lead manufacturers can produce 63.0% IACS soft aluminum wires, but the stability of the production process and the qualified rate of the electric conductivity are still to be further improved. In order to further improve the conductivity of the soft aluminum conductor and improve the stability of the batch preparation process of the soft aluminum conductor, research on alloy components and preparation processes of the high-conductivity soft aluminum wire needs to be developed to obtain a material optimization formula and a preparation process, and a technical support is provided for production, application and popularization of the high-conductivity soft aluminum wire and a lead thereof, so that the loss of the power transmission line in China is further reduced, and the green, environment-friendly, safe and efficient operation of the power grid in China is supported.

Disclosure of Invention

Therefore, the invention aims to overcome the defects that the production process of the high-conductivity soft aluminum wire in the prior art is poor in stability, the conductivity qualified rate is yet to be further improved and the like, and provides the soft aluminum wire and the preparation method thereof.

In order to solve the technical problems, the invention provides the following technical scheme:

a soft aluminum wire comprises the following components in percentage by mass: 0.002-0.05%, Y: 0.001-0.10%, Si: 0-0.06%, Fe: 0-0.12 percent of the total weight of the alloy, less than or equal to 0.01 percent of V, Ti, Cr and Mn and the balance of aluminum and inevitable impurity elements.

Further, the paint comprises the following components in percentage by mass: 0.002-0.03%, Y: 0.01 to 0.05%, Si: 0-0.05%, Fe: 0.01-0.10 percent of aluminum, less than or equal to 0.008 percent of V, Ti, Cr and Mn and the balance of aluminum and inevitable impurity elements.

The invention also provides a preparation method of the soft aluminum wire, which is characterized by comprising the following steps:

smelting: melting an aluminum ingot, adding Al-B alloy into the aluminum melt, standing, and then adding Al-Y alloy for smelting;

refining: adding a covering agent, refining in a nitrogen atmosphere, standing and slagging off;

casting: casting the aluminum alloy liquid according to a preset size to obtain an aluminum alloy ingot;

rod making: rolling the aluminum alloy ingot into an aluminum alloy rod after heat preservation;

drawing: carrying out wire drawing treatment on the aluminum alloy rod to obtain an aluminum monofilament;

annealing: and annealing the aluminum monofilament to obtain the soft aluminum wire.

Further, the annealing temperature is 330-380 ℃, and the annealing time is 2-5 h.

Further, the smelting temperature is 750-770 ℃;

the standing time after the Al-B alloy is added is 20-40 min.

Further, the refining temperature is 730-.

Further, the standing time in the refining step is 20-40 min;

the addition amount of the covering agent is 0.01-0.03% of the total feeding mass. The covering agent used by the invention is a general product for aluminum alloy smelting (the main components are KCl, NaCl, KF, Na2SiF6, AlCl3 and cryolite (Na3AlF6)), and special requirements are not needed in the invention.

Further, the casting temperature is 720-730 ℃.

Further, the heat preservation temperature in the rod making step is 400-450 ℃, and the heat preservation time is 40-80 min.

Further, the wire drawing speed is 13-16m/s, and the deformation is 20-25%.

The preparation process provided by the invention is characterized in that: smelting, namely sequentially putting all intermediate alloys into an industrial pure aluminum ingot after the industrial pure aluminum ingot is completely molten, wherein the alloying temperature is 750-770 ℃; stirring the aluminum liquid by using a stirrer to fully homogenize alloy elements; by using N₂Degassing the aluminum liquid, removing slag, performing covering agent anti-oxidation treatment, standing for 30min, slagging off and casting aluminum alloy liquid, and casting into alloy ingots with the size of 22 x 380mm by adopting red copper molds; pressing an aluminum alloy ingot into a round rod with phi 9.5mm by adopting a hot rolling mode, then drawing wires, cold drawing the wires on a wire drawing machine at the speed of 15m/s, drawing the wires by using a steel die for multiple times,obtaining 3.05-3.60 mm of aluminum monofilaments; and annealing the aluminum monofilament by using an annealing furnace to finally prepare the soft aluminum monofilament.

Most preferably, the preparation method of the soft aluminum wire provided by the invention specifically comprises the following steps:

smelting: melting an aluminum ingot at 750-770 ℃, adding an Al-B alloy into the aluminum melt, standing for 30min, and adding an Al-Y alloy;

refining: introducing nitrogen at 730-740 ℃ for 10-15min, standing for 30min, and then slagging off;

casting: casting the aluminum alloy liquid into a mold at 720-730 ℃ to prepare an aluminum alloy ingot with the size of 22mm multiplied by 380 mm; in order to reduce the introduction of Fe, the die is made of red copper;

rod making: keeping the temperature of the aluminum alloy ingot prepared in the step at 400-450 ℃ for 1h, and then rolling the aluminum alloy ingot into an aluminum alloy rod with the phi of 9.5 mm;

drawing: and (3) drawing at a speed of 15m/s and a deformation of 20-25% to obtain the aluminum monofilament with the diameter of 3.05-3.60 mm.

Annealing treatment: annealing the aluminum monofilament prepared in the step to prepare a soft aluminum monofilament line, wherein the annealing temperature is as follows: and (3) annealing at 330-380 ℃ for: 2-5 h.

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

y: according to the technical scheme, the effect of adding 0.01-0.20% of yttrium element on improving the conductivity of the aluminum alloy is mainly due to the fact that Y and main solid-solution impurity elements Fe and Si in aluminum have strong interaction, rare earth compounds formed by Y and impurity atoms are separated out at a crystal boundary, and the solid solubility of the impurity elements such as 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, impurities such as Fe, Si and the like react with Y to generate compounds, and the compound is precipitated at a crystal boundary, so that the scattering effect of the solid solution Fe and Si on electrons is reduced, and the conductivity of the aluminum alloy can be improved by adding a proper amount of Y. However, excessive Y forms impurities to affect the conductivity, and the increase of the Y content enhances the grain refinement effect and increases the scattering of electrons, thereby reducing the conductivity of the aluminum conductor. Therefore, the content of Y should be controlled within a certain range to ensure the conductivity of the aluminum conductor.

Si: according to the technical scheme, 0-0.05% of Si is adopted, and the Si is mainly silicon dioxide or silicate in bauxite and is a main 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 mainly due to the fact that Si is a semiconductor and has a much higher resistivity than the aluminum matrix, so that an increase in the Si content will reduce the effective conductive cross-sectional area of the aluminum matrix and reduce the conductivity of the aluminum alloy, and therefore the Si content should be effectively controlled, and if the Si content exceeds the requirement, a rare earth treatment is usually employed.

Fe: the technical scheme of the invention adopts Fe: 0-0.12%, and the aluminum contains a certain amount of iron, which is a main 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. Iron reduces the conductivity of aluminum, but since iron has a low solid solubility at room temperature, its effect on the conductivity of aluminum is relatively low compared to other elements. Of course, the content of iron cannot be too high, and if the content of iron is higher, the conductivity is reduced, and the phenomenon of brittle fracture in the processing process can also occur due to uneven distribution.

B: among the many factors, the chemical composition is the most basic factor affecting the conductivity of the aluminum conductor, so reducing the effect of impurity elements on the conductivity is a key factor in improving the conductivity of the aluminum conductor. If the impurity element exists in a solid solution state, the influence on the electrical conductivity is large. Boronization is an effective way to reduce the level of impurities. The technical scheme of the invention adopts the following steps: 0.002-0.05%, namely after a certain amount of B element is added into the electrical aluminum, the B element can react with impurity elements such as transition group impurity elements Cr, Mn, V, Ti and the like to form insoluble boride, and the insoluble boride is separated from the aluminum liquid in the form of aluminum slag, so that the purposes of reducing the content of the impurity elements and improving the conductivity are achieved.

Cr, Mn, V, Ti: in the invention, V + Ti + Cr + Mn is controlled to be less than or equal to 0.01 percent, and the four elements are 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 technical scheme of the invention has the following advantages:

1. the soft aluminum wire provided by the invention comprises the following components in percentage by mass, B: 0.002-0.05%, Y: 0.001-0.10%, Si: 0-0.06%, Fe: 0-0.12 percent of the total weight of the alloy, less than or equal to 0.01 percent of V, Ti, Cr and Mn and the balance of aluminum and inevitable impurity elements. According to the invention, on the basis of strict purification control of impurity elements through boron, trace Y rare earth elements are added into the aluminum alloy, so that the impurity content can be reduced, the effects of grain refinement and crystallization temperature increase are achieved, and the aluminum conductor has high conductivity and good mechanical properties to a certain extent; the conductivity of the provided soft aluminum wire material is more than or equal to 63.5 percent IACS (20 ℃), the tensile strength is more than or equal to 75MPa, and the elongation is more than or equal to 20.0 percent.

2. The preparation method of the soft aluminum wire provided by the invention adopts the blowing of N in the smelting process₂Degassing, deslagging and adding a covering agent to prevent oxidation; annealing heat treatment is adopted to improve or eliminate various microstructure defects and residual stress caused in the casting, rolling and wire drawing processes of the aluminum wire, the structure is improved to optimize the electrical and mechanical properties of the aluminum wire, particularly, annealing treatment with the annealing temperature of 350-400 ℃ and the annealing time of 2-4 h is selected, and the internal stress of the soft aluminum wire is eliminated by utilizing recovery recrystallization, so that the electric conductivity and the elongation of the soft aluminum wire are further improved, the strength is reduced, and the production worker is skilled in the artThe process is stable, and the qualification rate of the product is more than 95 percent.

In the preparation process, no aluminum-iron alloy is required to be added additionally, because the original industrial pure aluminum ingot (99.7 wt.% Al) contains a certain amount of iron which is a main impurity in pure aluminum; meanwhile, 99.7 wt.% of aluminum ingots are selected, compared with 99.8 wt.% of aluminum ingots in the prior art, the requirement on raw materials is reduced, the cost is reduced, and the stability of the process and the qualification rate of products are improved. In addition, tools used for melting and casting are mainly steel or cast iron, Fe elements are carried into aluminum by these tools, and iron and scrap iron may be mixed in remelting scrap, and iron and silicon are present as impurities in the present invention and are undesirable components.

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.