CN117701951A - High-conductivity super heat-resistant aluminum alloy monofilament material and preparation method thereof - Google Patents

Abstract

The invention provides a high conductivity super heat-resistant aluminum alloy single wire material and a preparation method thereof. The alloy single wire includes the following elements in mass percentage: Zr: 0.2~0.4%, Ce(La): 0.2~ 0.3%, Be: 0.2~0.4%, B: 0.02~0.03%, Si ≤ 0.06%, Fe ≤ 1.5%, the remaining content is aluminum and other inevitable trace impurities; the obtained high conductivity super heat-resistant aluminum alloy The conductivity of the single filament is not less than 61.5% IACS (20℃), the tensile strength is not less than 160MPa, the elongation is not less than 2%, and the room temperature strength residual rate after 1 hour at 280℃ is ≥90%. Its preparation methods include smelting, refining, casting, rolling, drawing and annealing. The technical solution provided by the invention solves the disadvantages of poor electrical conductivity and high transmission line loss of high conductivity super heat-resistant aluminum alloy monofilaments in the prior art.

Description

A high conductivity super heat-resistant aluminum alloy monofilament material and its preparation method

Technical areas:

The invention belongs to the technical field of electrical conductor materials and relates to the invention of a high conductivity super heat-resistant aluminum alloy monofilament material and a preparation method thereof.

Background technique:

Constructing a new power system with new energy as the main body and building safe and efficient transmission lines are major national needs. However, the current transmission lines mainly use ordinary steel-core aluminum stranded wires, which have low heat-resistant temperature, small transmission capacity margin, and high-temperature operation arc. The vertical expansion seriously restricts the safe and efficient transmission of electric energy and the large-scale consumption of new energy.

Super heat-resistant aluminum alloy wire is a special capacity-increasing wire with good performance. The maximum allowable operating temperature is 210℃ (the room temperature strength residual rate is more than 90% after 1 hour of insulation at 280℃). There is no need to replace the tower, and the original wire can be directly replaced. Capacity can be increased by more than 1 times. However, the electrical conductivity of existing super heat-resistant aluminum alloy wires is 60% IACS, which is 1% IACS lower than ordinary steel-core aluminum stranded wires. It has poor electrical conductivity and high transmission line losses. Therefore, it is necessary to develop a super heat-resistant aluminum alloy monofilament material with high conductivity to meet the needs of existing technology.

Contents of the invention:

The purpose of this invention is to use aluminum ingots with purity ≥99.7% as raw materials to develop a high conductivity super heat-resistant aluminum alloy monofilament material to solve the problem of low conductivity and low conductivity of existing super heat-resistant aluminum alloy monofilament and wire products. High technical difficulties.

The technical solutions to achieve the technical objectives of the present invention are as follows:

A high conductivity super heat-resistant aluminum alloy single wire material. The aluminum alloy single wire includes the following mass percentage of alloy elements: Zr: 0.2~0.4%, Ce(La): 0.2~0.3%, Be: 0.2~ 0.4%, B: 0.02~0.03%, Si≤0.06%, Fe≤1.5%, the rest is aluminum content and other inevitable impurities.

Preferably: the aluminum alloy single wire includes the following mass percentage of alloying elements: Zr: 0.40%, Ce: 0.30%, Be: 0.40%, B: 0.03%, Si: 0.06%, Fe: 1.50%, and the rest are Aluminum content and other unavoidable impurities.

Preferably: the aluminum alloy single wire includes the following mass percentage of alloying elements: Zr: 0.20%, La: 0.20%, La: 0.20%, Be: 0.20%, B: 0.02%, Si: 0.06%, Fe: 1.00%, the rest is the aluminum content and other inevitable impurities.

Preferably: the aluminum alloy single wire includes the following mass percentage of alloying elements: Zr: 0.30%, Ce+La: 0.15%, Be: 0.30%, B: 0.02%, Si: 0.05%, Fe: 1.2%, The remainder is the aluminum content and other unavoidable impurities.

Preferably: the aluminum alloy single wire includes the following mass percentage of alloying elements: Zr: 0.25%, La: 0.27%, Be: 0.35%, B: 0.025%, Si: 0.04%, Fe: 0.9%, and the rest are Aluminum content and other unavoidable impurities.

Preferably: the aluminum alloy single wire includes the following mass percentage of alloying elements: Zr: 0.35%, Ce: 0.22%, Be: 0.25%, B: 0.03%, Si: 0.05%, Fe: 1.1%, and the rest are Aluminum content and other unavoidable impurities.

Preferred: The alloy single wire super heat-resistant aluminum alloy single wire has conductivity ≥ 61% IACS (20°C), tensile strength ≥ 160MPa, elongation ≥ 2%, and room temperature strength residual rate after 1 hour of insulation at 280°C ≥ 90 %.

Based on the same inventive concept, this application also provides a method for making high conductivity and super heat-resistant aluminum alloy monofilament materials. The method includes the following steps:

Smelting: Select industrial pure aluminum ingots with a purity of ≥99.7% and add them to the smelting furnace. After the pure aluminum is completely melted, add the master alloy for boronization treatment; then add the master alloy or mixed rare earths, stir for 10 to 15 minutes after complete melting, and keep warm. Leave for 20~30min;

Refining: Blow in nitrogen (N ₂ ) at 710 to 720°C, blow for 10 to 15 minutes, keep warm and stand for 10 to 20 minutes, then remove the slag;

Casting: Pour the aluminum alloy liquid into the preheated metal mold at 690~710°C and cast it into an aluminum ingot.

Preferred: wherein the melting temperature is 730 to 750°C.

Preferable: wherein the preheating temperature is 250-300°C.

Preferably: the method further includes the following steps:

Rolling: Keep the aluminum ingot at 510-530°C for 1-3 hours and then roll it. After multiple passes, it will be rolled into an aluminum alloy round bar and then kept at 400-450°C for 20-40 hours;

Drawing: The aluminum alloy round rod cooled to room temperature is drawn through multiple passes to obtain aluminum alloy single wire;

Annealing: The monofilament is kept at 100-140°C for 1-4 hours and then air-cooled.

Compared with the closest existing technology, the beneficial effects of the present invention include:

First of all, it should be explained that in the technical solution provided by the present invention, the functions and mechanisms of the alloying elements with a specific amount and the joint representation of each alloying element under the process conditions of the present invention are as follows:

Zirconium Zr: The addition of an appropriate amount of zirconium can significantly improve the heat resistance of aluminum alloys. This is mainly due to the fact that the atomic radius of zirconium is slightly larger than the atomic radius of aluminum. Zirconium diffuses in aluminum in a substitutional manner. Its diffusion activation energy is high and moves toward sub-atomic size. A fine Al ₃ Zr phase precipitates at the crystal grain boundary. It is not easy to aggregate and grow. It has high stability and can prevent recrystallization. It can still effectively pin dislocations and grain boundaries at higher temperatures, hindering deformation and Intra-granular and grain boundary slip increases creep resistance, thus improving the heat resistance of aluminum alloys.

Cerium (lanthanum) (Ce(La)): In the present invention, one of La, Ce or La-Ce mixed rare earths is added, which can modify the microstructure and effectively improve the morphology of the eutectic structure. On the one hand, these rare earth elements can form high-melting-point compounds with Al, impurity elements Fe, Si, etc. During the solidification process, high-melting-point compounds precipitate first, providing a large number of heterogeneous nucleation points. On the other hand, rare earth elements segregate at the solid-liquid interface, which can increase the component fluctuations near the interface and increase the supercooling of the components at the solid-liquid interface. It is conducive to non-spontaneous nucleation, thereby achieving the effect of refining grains. At the same time, cerium (lanthanum) can also refine coarse micron-sized particles such as AlFeSi in the cast structure and change their morphology, which is beneficial to improving the conductivity and ductility of the alloy.

Beryllium (Be): Adding a small amount of beryllium to the aluminum alloy melt will form a protective film of beryllium oxide on the surface of the melt, which can reduce slag and outgassing, improve purity, and improve fluidity, resulting in high purity and good surface finish. Castings; beryllium can transform the brittle iron intermetallic compound crystals in aluminum alloys from coarse needles and layers into fine equiaxed shapes, thereby improving the strength and plasticity of castings; adding beryllium during the heat treatment process can promote the formation of aluminum alloys. The age hardening process improves the strength of the alloy.

Boron (B): Among many influencing factors, chemical composition is the most basic factor affecting the conductivity of aluminum conductors. Therefore, reducing the impact of impurity elements on conductivity is the key to improving the conductivity of aluminum conductors. If impurity elements exist in the state of solute atoms, they will have a greater impact on conductive properties. Borination treatment is an effective method to reduce the content of harmful impurities in aluminum alloy conductor materials. That is, after adding a certain amount of B element to the aluminum alloy, it can react with the transition group impurity elements Cr, Mn, V, Ti, etc., making it The solute atomic state is transformed into a combined state and deposited at the bottom of the melt, thereby improving the conductive properties of the aluminum alloy.

Silicon (Si): Silicon is one of the main impurity elements in industrial aluminum. Si can react with Al, Fe, and RE elements to form a second phase, which reduces lattice distortion and improves the electrical conductivity, mechanical properties and resistance of aluminum alloy conductor materials. Thermal properties play a beneficial role.

Iron (Fe): Aluminum contains a certain amount of iron and is a major impurity in industrial aluminum. Iron is harmful to the mechanical properties of cast aluminum because it usually appears in the form of coarse primary crystals or in the form of aluminum-iron-silicon compounds, which increase the strength of aluminum to a certain extent but reduce the ductility of aluminum. Studies have shown that iron can increase the strength of aluminum conductors without significantly reducing its conductivity. However, there is also data showing that in actual production, too high Fe in an aluminum conductor will significantly increase its resistivity, so attention should also be paid to controlling the iron content.

Under the preparation process of the present invention, the heat resistance of the alloy is improved after the Zr element is added. After long-term high-temperature heat treatment, the Al3Zr phase is generated, which reduces the lattice distortion and improves the strength and strength of the alloy while ensuring the heat resistance. Electrical conductivity; Ce (La) and Be form high melting point compounds with Al, impurity elements Fe, Si, etc., which can reduce the solid solubility of Fe and Si elements in the alloy, and refine the coarse microns such as AlFeSi in the cast structure grade particles, improving the mechanical properties and electrical conductivity of the alloy; at the same time, the addition of Be element reduces oxide inclusions, improves the quality of the aluminum alloy liquid, accelerates the aging precipitation process of Al3Zr, and improves the strength and electrical conductivity of the aluminum alloy; On the basis of ensuring strength and heat resistance, the conductivity is increased to above 61.5% IACS. Through the reasonable matching of the ingredient formula patented by the invention and the preparation process parameters, the conductivity of the super heat-resistant aluminum alloy single wire prepared is ≥61.5% IACS (20°C), the tensile strength is ≥160MPa, and the elongation is ≥2.0%. The room temperature strength retention rate after 1 hour at 280°C is ≥90%.

Detailed ways

The claims of the present invention have two independent claims: The technical solution to achieve the technical purpose of the present invention is as follows:

A high conductivity super heat-resistant aluminum alloy monofilament material. The alloy monofilament includes the following alloy elements in mass percentage: Zr: 0.2~0.4%, Ce(La): 0.2~0.3%, Be: 0.2 ~0.4%, B: 0.02~0.03%, Si ≤ 0.06%, Fe ≤ 1.5%, the rest is the aluminum content and other inevitable trace impurities.

The independent claim for this product has two categories of technical features that further define it: components and performance of the resulting product.

The preparation method includes the following steps:

(1) Smelting: Select industrial pure aluminum ingots with a purity of ≥99.7% and add them to the smelting furnace at a melting temperature of 730 to 750°C; after the pure aluminum is completely melted, add Al-B master alloy at 730 to 750°C for boronization treatment; Add Al-Ce (Al-La) master alloy or La-Ce mixed rare earth or Al-Be master alloy at 730~750°C, stir for 10~15 minutes after complete melting, and keep warm for 20~30 minutes.

(2) Refining: Blow in nitrogen (N2) at 710~720℃, blow for 10~15min, keep warm and let stand for 10~20min, then remove the slag.

(3) Casting: Pour the aluminum alloy liquid into a metal mold preheated at 250-300°C at 690-710°C and cast it into an aluminum ingot with a cross-section of 20×20mm.

(4) Rolling: The aluminum ingot is kept at 510~530℃ for 1~3h and then rolled. After 7 passes, it is rolled into a φ9.5mm aluminum alloy round bar and then kept at 400~450℃ for 20~40h.

(5) Drawing: The aluminum alloy round rod cooled to room temperature is drawn through multiple passes to obtain φ3~4mm aluminum alloy single wire.

(6) Annealing: The monofilament is kept at 100-140°C for 1-4 hours and then air-cooled.

The technical solutions of the two independent claims will be described in detail below through the following specific examples. Unless otherwise stated, the percentages in the present invention are mass percentages.

Example 1

A kind of high conductivity super heat-resistant aluminum alloy monofilament material, the components and their mass fractions are:

(1) Smelting: Select industrial pure aluminum ingots with a purity of ≥99.7% and add them to the smelting furnace. The melting temperature is 750℃; after the pure aluminum is completely melted, add Al-B master alloy at 750℃ for boronization treatment; add Al at 750℃ -Ce master alloy, Al-Be master alloy, stir for 15 minutes after complete melting, keep warm and let stand for 30 minutes.

(2) Refining: Blow in nitrogen (N ₂ ) at 720°C for 15 minutes, keep it warm for 20 minutes and then remove the slag.

(3) Casting: Pour the aluminum alloy liquid at 710°C into a metal mold preheated at 300°C and cast it into an aluminum ingot with a cross-section of 20×20mm.

(4) Rolling: The aluminum ingot is heated at 530°C for 1 hour and then rolled. After 7 passes, it is rolled into a φ9.5mm aluminum alloy round bar and then kept at 450°C for 20 hours.

(5) Drawing: The aluminum alloy round rod cooled to room temperature is drawn through multiple passes to obtain φ4mm aluminum alloy single wire.

(6) Annealing: The monofilament is kept at 140°C for 1 hour and then air-cooled.

The super heat-resistant aluminum alloy monofilament thus prepared has a conductivity of 61.5% IACS (20°C), a tensile strength of 172MPa, an elongation of 2.0%, and a room temperature strength retention rate of 95% after being held at 280°C for 1 hour.

Example 2

A kind of high conductivity super heat-resistant aluminum alloy monofilament material, the components and their mass fractions are:

(1) Smelting: Select industrial pure aluminum ingots with a purity of ≥99.7% and add them to the smelting furnace. The melting temperature is 730°C; after the pure aluminum is completely melted, add Al-B master alloy at 730°C for boronization treatment; add Al at 730°C. -La master alloy, Al-Be master alloy, stir for 10 minutes after complete melting, keep warm and let stand for 20 minutes.

(2) Refining: Blow in nitrogen (N ₂ ) at 710°C for 10 minutes, keep warm and stand for 10 minutes, then remove the slag.

(3) Casting: Pour the aluminum alloy liquid at 690°C into a metal mold preheated at 250°C and cast it into an aluminum ingot with a cross-section of 20×20mm.

(4) Rolling: The aluminum ingot is kept at 510°C for 3 hours and then rolled. After 7 passes, it is rolled into a φ9.5mm aluminum alloy round bar and then kept at 400°C for 40 hours.

(5) Drawing: The aluminum alloy round rod cooled to room temperature is drawn in multiple passes to obtain φ3mm aluminum alloy single wire.

(6) Annealing: The monofilament is kept at 100°C for 4 hours and then air-cooled.

The super heat-resistant aluminum alloy monofilament thus prepared has a conductivity of 61.8% IACS (20°C), a tensile strength of 160MPa, an elongation of 2.5%, and a room temperature strength retention rate of 90% after being held at 280°C for 1 hour.

Example 3

A kind of high conductivity super heat-resistant aluminum alloy monofilament material, the components and their mass fractions are:

(1) Smelting: Select industrial pure aluminum ingots with a purity of ≥99.7% and add them to the smelting furnace. The melting temperature is 740°C; after the pure aluminum is completely melted, add Al-B master alloy at 740°C for boronization treatment; add La at 740°C. -Ce mixed rare earth and Al-Be master alloy, stir for 10 minutes after complete melting, keep warm and let stand for 25 minutes.

(2) Refining: Blow in nitrogen (N ₂ ) at 715°C for 10 minutes, keep it warm for 15 minutes and then remove the slag.

(3) Casting: Pour the aluminum alloy liquid at 700°C into a metal mold preheated at 280°C and cast it into an aluminum ingot with a cross-section of 20×20mm.

(4) Rolling: The aluminum ingot is kept at 520°C for 2 hours and then rolled. After 7 passes, it is rolled into a φ9.5mm aluminum alloy round bar and then kept at 420°C for 30 hours.

(5) Drawing: The aluminum alloy round rod cooled to room temperature is drawn through multiple passes to obtain φ3.84mm aluminum alloy single wire.

(6) Annealing: The monofilament is kept at 110°C for 3 hours and then air-cooled.

The super heat-resistant aluminum alloy monofilament thus prepared has a conductivity of 61.6% IACS (20°C), a tensile strength of 168MPa, an elongation of 2.1%, and a room temperature strength retention rate of 92% after being held at 280°C for 1 hour.

Example 4

A kind of high conductivity super heat-resistant aluminum alloy monofilament material, the components and their mass fractions are:

(1) Smelting: Select industrial pure aluminum ingots with a purity of ≥99.7% and add them to the smelting furnace. The melting temperature is 735℃; after the pure aluminum is completely melted, add Al-B master alloy at 735℃ for boronization treatment; add Al at 735℃ -La master alloy, Al-Be master alloy, stir for 12 minutes after complete melting, keep warm and let stand for 25 minutes.

(2) Refining: Blow in nitrogen (N ₂ ) at 720°C for 15 minutes, keep it warm for 10 minutes and then remove the slag.

(3) Casting: Pour the aluminum alloy liquid at 705°C into a metal mold preheated at 260°C and cast it into an aluminum ingot with a cross-section of 20×20mm.

(4) Rolling: The aluminum ingot is kept at 525°C for 2 hours and then rolled. After 7 passes, it is rolled into a φ9.5mm aluminum alloy round bar and then kept at 440°C for 25 hours.

(5) Drawing: The aluminum alloy round rod cooled to room temperature is drawn through multiple passes to obtain φ3.5mm aluminum alloy single wire.

(6) Annealing: The monofilament is kept at 120°C for 2 hours and then air-cooled.

The super heat-resistant aluminum alloy monofilament thus prepared has a conductivity of 61.6% IACS (20°C), a tensile strength of 165MPa, an elongation of 2.4%, and a room temperature strength retention rate of 91% after being held at 280°C for 1 hour.

Example 5

A kind of high conductivity super heat-resistant aluminum alloy monofilament material, the components and their mass fractions are:

(1) Smelting: Select industrial pure aluminum ingots with a purity of ≥99.7% and add them to the smelting furnace. The melting temperature is 745℃; after the pure aluminum is completely melted, add Al-B master alloy at 745℃ for boronization treatment; add Al at 745℃ -Ce master alloy, Al-Be master alloy, stir for 12 minutes after complete melting, keep warm and let stand for 25 minutes.

(2) Refining: Blow in nitrogen (N ₂ ) at 710°C for 10 minutes, keep it warm for 20 minutes and then remove the slag.

(3) Casting: Pour the aluminum alloy liquid at 695°C into a metal mold preheated at 250°C and cast it into an aluminum ingot with a cross-section of 20×20mm.

(4) Rolling: The aluminum ingot is heated at 515°C for 3 hours and then rolled. After 7 passes, it is rolled into a φ9.5mm aluminum alloy round bar and then kept at 410°C for 35 hours.

(5) Drawing: The aluminum alloy round rod cooled to room temperature is drawn through multiple passes to obtain φ3.3mm aluminum alloy single wire.

(6) Annealing: The monofilament is kept at 130°C for 2 hours and then air-cooled.

The super heat-resistant aluminum alloy monofilament thus prepared has a conductivity of 61.7% IACS (20°C), a tensile strength of 163MPa, an elongation of 2.2%, and a room temperature strength retention rate of 90% after being held at 280°C for 1 hour.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the present invention can still be modified. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall be covered by the claims of the present invention.

Claims (11)

1. A high conductivity super heat-resistant aluminum alloy single wire material, characterized in that the aluminum alloy single wire includes the following mass percentage of alloy elements: Zr: 0.2~0.4%, Ce (La): 0.2~0.3 %, Be: 0.2~0.4%, B: 0.02~0.03%, Si ≤ 0.06%, Fe ≤ 1.5%, the rest is the aluminum content and other inevitable impurities. 2. A high conductivity super heat-resistant aluminum alloy monofilament material as claimed in claim 1, characterized in that: the aluminum alloy monofilament includes the following mass percentage of alloying elements: Zr: 0.40%, Ce: 0.30 %, Be: 0.40%, B: 0.03%, Si: 0.06%, Fe: 1.50%, the rest is the aluminum content and other inevitable impurities. 3. A high conductivity super heat-resistant aluminum alloy monofilament material as claimed in claim 1, characterized in that: the aluminum alloy monofilament includes the following mass percentage of alloying elements: Zr: 0.20%, La: 0.20 %, La: 0.20%, Be: 0.20%, B: 0.02%, Si: 0.06%, Fe: 1.00%, the rest is the aluminum content and other inevitable impurities. 4. A kind of high conductivity super heat-resistant aluminum alloy monofilament material as claimed in claim 1, characterized in that: the aluminum alloy monofilament includes the following mass percentage of alloying elements: Zr: 0.30%, Ce+La : 0.15%, Be: 0.30%, B: 0.02%, Si: 0.05%, Fe: 1.2%, the rest is the aluminum content and other inevitable impurities. 5. A kind of high conductivity super heat-resistant aluminum alloy single wire material as claimed in claim 1, characterized in that: the aluminum alloy single wire includes the following mass percentage of alloying elements: Zr: 0.25%, La: 0.27 %, Be: 0.35%, B: 0.025%, Si: 0.04%, Fe: 0.9%, the rest is the aluminum content and other inevitable impurities. 6. A high conductivity super heat-resistant aluminum alloy single wire material as claimed in claim 1, characterized in that: the aluminum alloy single wire includes the following mass percentage of alloying elements: Zr: 0.35%, Ce: 0.22 %, Be: 0.25%, B: 0.03%, Si: 0.05%, Fe: 1.1%, the rest is the aluminum content and other inevitable impurities. 7. A kind of high conductivity super heat-resistant aluminum alloy monofilament material as claimed in claim 1, characterized in that: the conductivity of the aluminum alloy monofilament is ≥ 61% IACS, the tensile strength is ≥ 160 MPa, and the elongation is ≥ 2 %, the room temperature strength retention rate after 1 hour at 280°C is ≥90%. 8. A method for preparing a high conductivity super heat-resistant aluminum alloy monofilament material according to any one of claims 1 to 7, characterized in that: the method includes the following steps: Smelting: Select industrial pure aluminum ingots with a purity of ≥99.7% and add them to the smelting furnace. After the pure aluminum is completely melted, add the master alloy for boronization treatment; then add the master alloy or mixed rare earths, stir for 10 to 15 minutes after complete melting, and keep warm. Leave for 20~30min; Refining: Blow in nitrogen at 710~720℃, blow for 10~15min, keep it warm and stand for 10~20min, then remove the slag; Casting: Pour the aluminum alloy liquid into the preheated metal mold at 690~710°C and cast it into an aluminum ingot. 9. The method of claim 8, wherein the melting temperature is 730-750°C. 10. The method of claim 8, wherein the preheating temperature is 250-300°C. 11. The method of claim 8, characterized in that: the method further includes the following steps: Rolling: Keep the aluminum ingot at 510~530℃ for 1~3h and then roll it. After multiple passes, it will be rolled into an aluminum alloy round bar and then kept at 400~450℃ for 20~40h; Drawing: The aluminum alloy round rod cooled to room temperature is drawn through multiple passes to obtain aluminum alloy single wire; Annealing: The monofilament is kept at 100-140°C for 1-4 hours and then air-cooled.