Preparation method of low-cost super-heat-resistant aluminum alloy wire single filament

Abstract

The application discloses a preparation method of low-cost super-heat-resistant aluminum alloy wire monofilament and belongs to the technical field of wire and cable preparation. The super-heat-resistant aluminum alloy wire monofilament is prepared through an alloy smelting-gas-assisted continuous casting and extrusion-drawing process. The principle of the application is that the alloy rod containing nanoscale Al6Fe phase is obtained through the gas-assisted continuous casting and extrusion, the grain boundary density of the cross section of the alloy rod is increased through drawing to improve the strength, and finally the super-heat-resistant aluminum alloy wire monofilament is obtained. The production method has the advantages of low raw material cost, short production flow and low energy consumption, and can significantly reduce the production cost of the super-heat-resistant aluminum alloy wire monofilament.

Description

Technical Field

[0001] This invention relates to a low-cost method for preparing ultra-heat resistant aluminum alloy conductor monofilaments, belonging to the field of wire and cable manufacturing technology. Background Technology

[0002] Since Harrington discovered in 1949 that Zr could improve the heat resistance of pure aluminum, the research and development of heat-resistant aluminum alloy conductors has focused on Al-Zr alloys. Among them, ultra-heat-resistant aluminum alloy conductors have a high heat resistance rating, with a maximum allowable continuous operating temperature above 210℃ and a transmission capacity more than twice that of ordinary hard aluminum wires, making them an important direction for the future development of heat-resistant aluminum alloy conductors. However, it is worth noting that in the preparation process of such conductors, in order to fully extract Zr dissolved in the aluminum matrix, a long heat treatment is usually required. The low production efficiency significantly increases production costs, causing the price of such conductors to be more than three times that of ordinary hard aluminum wires, thus restricting their widespread application.

[0003] Fe is the most common impurity element in aluminum alloys. During equilibrium solidification, the Al3Fe phase formed by Fe and Al often appears as coarse needle-like or flaky structures, which reduces the strength and toughness of the alloy. However, if the cooling rate of the alloy melt is increased, the iron-containing phase will transform into a dispersed Al6Fe phase, which can significantly improve the mechanical properties of the alloy. In addition, the Al6Fe phase has good stability below 300℃, and the extremely low solid solubility of Fe in the aluminum matrix is ​​conducive to obtaining high conductivity. Therefore, Al-Fe alloys are promising for use in ultra-heat resistant aluminum alloy wires.

[0004] However, in order to improve the cooling rate of the alloy melt, that is, to quickly remove the latent heat of crystallization and physical heat during the solidification process, the size of the melt in at least one direction needs to be reduced. Therefore, non-equilibrium solidified products are mostly in the form of thin sheets, filaments or powders. If these small-sized materials are made into wires, a more complex process is required, which is costly and has very low production efficiency. Therefore, the development of Al-Fe alloy monofilaments that can be used for ultra-heat resistant aluminum alloy wires urgently needs to overcome the technical bottlenecks for industrial application.

[0005] Patent CN202311757716.1 proposes a method for preparing high-strength, high-conductivity Al-Fe alloy wires, which utilizes a new non-equilibrium solidification technology—gas-assisted continuous casting and extrusion—to refine the iron-rich phase and improve the alloy's strength. However, it is worth noting that to obtain excellent mechanical properties, this patent employs a high Fe content (1-2%) and a large amount of plastic deformation (≥91%), which inevitably sacrifices the material's electrical conductivity or heat resistance, making it difficult to meet the current standards' comprehensive requirements for the strength, conductivity, and heat resistance of ultra-heat-resistant wires. Summary of the Invention

[0006] The purpose of this invention is to provide a low-cost method for preparing ultra-heat resistant aluminum alloy conductor monofilaments, specifically including the following steps:

[0007] (1) Material preparation: Weigh out the aluminum-iron master alloy and aluminum ingots according to the mass percentage of Fe: 0.8-0.95% and the balance Al.

[0008] (2) Melting: The aluminum-iron intermediate alloy and aluminum ingots are put into the furnace to melt and stirred until they are evenly mixed. During the stirring process, the temperature of the melt is maintained at 750-780℃, and finally held at 700-720℃ for 60 minutes.

[0009] (3) Al-Fe alloy rods were prepared by gas-assisted continuous casting and extrusion.

[0010] (4) The alloy rod obtained in step (3) is cold-drawn to obtain a super heat-resistant aluminum alloy wire monofilament.

[0011] Preferably, the diameter of the funnel in step (3) of the present invention is 2-4 mm, and the funnel needs to be heated to 730-750°C before pouring in the alloy melt.

[0012] Preferably, the inert gas in step (3) of the present invention is nitrogen, argon, etc., and the gas pressure is 0.10-0.18 MPa.

[0013] Preferably, the extrusion wheel speed in step (3) of the present invention is 5-10 rpm.

[0014] Preferably, in step (3) of the present invention, the preheating temperature of the extrusion die cavity is 300-350℃ and the die hole diameter is 9.5mm.

[0015] Preferably, in step (4) of the present invention, the cold drawing is performed 4-6 times, and the total deformation is 78-82%.

[0016] The principle of this invention is to obtain an alloy rod containing nanoscale Al6Fe phase by gas-assisted continuous casting and extrusion, and to increase the grain boundary density of the cross-section of the alloy rod by drawing to improve its strength, ultimately obtaining an ultra-heat resistant aluminum alloy wire monofilament.

[0017] The beneficial effects of this invention are:

[0018] (1) The nanoscale Al6Fe phase in the alloy is conducive to obtaining higher strength; the present invention has a fast cooling rate throughout the solidification process of the alloy melt, and nanoscale Al6Fe phase will be formed at the grain boundaries and within the grains. The large number of uniformly distributed hard particles have a strong pinning effect on dislocations, and the strengthening effect is significant.

[0019] (2) The excellent high-temperature stability of Al6Fe phase can ensure the heat resistance of single wire; the extremely low solid solubility and diffusion coefficient of Fe in aluminum means that the morphology and size of nano-sized Al6Fe phase in the alloy do not change after heat treatment at 300℃ / 10h, which can fully meet the test of 280℃ / 1h for ultra-heat resistant wire.

[0020] (3) The low solid solubility of Fe in α-Al is conducive to obtaining high conductivity; the use of low gas pressure in the gas-assisted continuous casting and extrusion process is conducive to controlling the solid solubility of Fe in α-Al to below 0.1%, thereby reducing the adverse effect of solid solution atoms on the conductivity of the alloy.

[0021] (4) The Al-Fe alloy wire monofilament prepared by this invention has a tensile strength of over 160 MPa and a conductivity of over 60.1% IACS at 20℃. At the same time, after heat exposure at 280℃ / 1h, the tensile strength retention rate can reach over 91%, which fully meets the requirements of current standards for ultra-heat resistant aluminum alloy wire monofilaments.

[0022] (5) The present invention uses Fe instead of Zr, which reduces the cost of raw materials; it eliminates the need for long heat treatment, shortens the process flow, and reduces energy consumption and processing costs. Therefore, the cost of preparing alloy monofilaments by the present invention is much lower than that of existing ultra-heat resistant aluminum alloy monofilaments, which is conducive to its widespread application. Attached Figure Description

[0023] Figure 1 A flowchart illustrating the preparation method of a low-cost, ultra-heat-resistant aluminum alloy conductor monofilament;

[0024] Figure 2 This is a schematic diagram of the principle of gas-assisted continuous casting and extrusion.

[0025] In the diagram: 1-funnel; 2-melt; 3-extrusion wheel; 4-extrusion wheel groove; 5-mold cavity; 6-mold; 7-extrusion rod; 8-air jet device. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0027] The apparatus used in the embodiments of the present invention is as follows: Figure 2 As shown, it includes 1-funnel, 2-melt, 3-extrusion wheel, 4-extrusion wheel groove, 5-mold cavity, 6-mold, 7-extrusion rod, and 8-air jet device; the molten metal 2 after melting flows out from the preheated funnel 1 located above the extrusion wheel 3 into the extrusion wheel groove 4. Inert gas is sprayed by the air jet device 8 above the extrusion wheel groove. Under the action of the inert gas, the melt spreads out tightly against the wall of the extrusion wheel groove and begins to solidify. Under the rotation of the extrusion wheel and the action of the plug on the mold cavity 5, the solidified billet is continuously extruded from the mold 6 to obtain the product alloy rod 7.

[0028] Example 1

[0029] This invention relates to a low-cost method for preparing ultra-heat resistant aluminum alloy conductor monofilaments, comprising the following steps:

[0030] (1) Material preparation: Weigh out the aluminum-iron master alloy and aluminum ingots according to the mass percentage of Fe: 0.9% and the balance of Al.

[0031] (2) Melting: The aluminum-iron intermediate alloy and aluminum ingots are put into the furnace to melt and stir until they are evenly mixed. During the stirring process, the temperature of the melt is maintained at 760℃. Finally, it is held at 700℃ for 60 minutes to complete the melting.

[0032] (3) Preparation of Al-Fe alloy rod by gas-assisted continuous casting and extrusion: The molten alloy flows out from a funnel (funnel diameter is 2.8 mm) located above the extrusion wheel groove. Inert gas (nitrogen gas, gas pressure is 0.15 MPa) is sprayed above the extrusion wheel groove. Under the combined action of gravity and inert gas jet, the alloy melt spreads along the extrusion wheel groove to form a thin metal layer. Under the action of the extrusion wheel (speed is 5 rpm) and the plug, the thin metal layer on the wheel groove wall continuously enters the mold and accumulates, and then is extruded from the die hole to form an alloy rod. The preheating temperature of the funnel is 740℃ and the die hole diameter is 9.5 mm.

[0033] (4) The alloy rod obtained in step (3) is drawn in multiple passes to obtain an alloy monofilament with a diameter of 4.1 mm. After being exposed to heat at 280°C for 1 hour, the tensile strength retention rate of the monofilament can reach 94.5%.

[0034] Example 2

[0035] This invention relates to a method for preparing a low-cost, ultra-heat-resistant aluminum alloy conductor monofilament, comprising the following steps:

[0036] (1) Material preparation: Weigh out the aluminum-iron master alloy and aluminum ingots according to the mass percentage of Fe: 0.8% and the balance of Al.

[0037] (2) Smelting: The aluminum-iron intermediate alloy and aluminum ingots are put into the furnace to melt and stir until they are evenly mixed. During the stirring process, the temperature of the melt is maintained at 750℃. Finally, it is held at 710℃ for 60 minutes to complete the smelting.

[0038] (3) Preparation of Al-Fe alloy rod by gas-assisted continuous casting and extrusion: The molten alloy flows out from a funnel (4.0 mm in diameter) located above the extrusion wheel groove. An inert gas (nitrogen gas, 0.10 MPa pressure) is sprayed above the extrusion wheel groove. Under the combined action of gravity and the inert gas jet, the alloy melt spreads along the extrusion wheel groove to form a thin metal layer. Under the action of the extrusion wheel (rotation speed of 8 rpm) and the plug, the thin metal layer on the groove wall continuously enters the mold and accumulates, and then is extruded from the die hole to form an alloy rod. The preheating temperature of the funnel is 740℃ and the die hole diameter is 9.5 mm.

[0039] (4) The alloy rod obtained in step (3) is drawn in multiple passes to obtain an alloy monofilament with a diameter of 4.05 mm. After being exposed to heat at 280°C for 1 hour, the tensile strength retention rate of the monofilament can reach 92.0%.

[0040] Example 3

[0041] This invention relates to a method for preparing a low-cost, ultra-heat-resistant aluminum alloy conductor monofilament, comprising the following steps:

[0042] (1) Material preparation: Weigh out the aluminum-iron master alloy and aluminum ingots according to the mass percentage of Fe: 0.95% and the balance of Al.

[0043] (2) Smelting: The aluminum-iron intermediate alloy and aluminum ingots are put into the furnace to melt and stir until they are evenly mixed. During the stirring process, the temperature of the melt is maintained at 780℃. Finally, it is held at 720℃ for 60 minutes to complete the smelting.

[0044] (3) Preparation of Al-Fe alloy rod by gas-assisted continuous casting and extrusion: The molten alloy flows out from a funnel (funnel diameter is 2.0 mm) located above the extrusion wheel groove. Inert gas (nitrogen gas, gas pressure is 0.18 MPa) is sprayed above the extrusion wheel groove. Under the combined action of gravity and inert gas jet, the alloy melt spreads along the extrusion wheel groove to form a thin metal layer. Under the action of the extrusion wheel (speed is 10 rpm) and the plug, the thin metal layer on the wheel groove wall continuously enters the mold and accumulates, and then is extruded from the die hole to form an alloy rod. The preheating temperature of the funnel is 750℃ and the die hole diameter is 9.5 mm.

[0045] (4) The alloy rod obtained in step (3) is drawn in multiple passes to obtain an alloy monofilament with a diameter of 4.3 mm. After being exposed to heat at 280°C for 1 hour, the tensile strength retention rate of the monofilament can reach 95.0%.

[0046] Comparative Example 1

[0047] (1) Material preparation: Weigh out the aluminum-iron master alloy and aluminum ingots according to the mass percentage of Fe: 2% and the balance of Al.

[0048] (2) Smelting: The aluminum-iron intermediate alloy and aluminum ingots are put into the furnace to melt and stir until they are evenly mixed. During the stirring process, the temperature of the melt is maintained at 740℃. Finally, it is held at 720℃ for 60 minutes to complete the smelting.

[0049] (3) Preparation of Al-Fe alloy rod by gas-assisted continuous casting and extrusion: The molten alloy flows out from a funnel (funnel diameter is 2.8 mm) located above the extrusion wheel groove. Inert gas (nitrogen gas, gas pressure is 0.4 MPa) is sprayed above the extrusion wheel groove. Under the combined action of gravity and inert gas jet, the alloy melt spreads along the extrusion wheel groove to form a thin metal layer. Under the action of the extrusion wheel (speed is 10 rpm) and the plug, the thin metal layer on the wheel groove wall continuously enters the mold and accumulates, and then is extruded from the die hole to form an alloy rod. The preheating temperature of the funnel is 820℃ and the die hole diameter is 10 mm.

[0050] (4) The 10mm alloy rod obtained in step (3) is drawn in multiple passes to obtain an alloy wire with a diameter of 2.5mm.

[0051] (5) After heat treatment at 200℃ for 3h, the alloy wire obtained in step (4) is used to obtain Al-Fe alloy single wire. After heat exposure at 280℃ for 1h, its tensile strength retention rate is 70%.

[0052] By comparing Examples 1, 2, and 3 with Comparative Example 1, it can be seen that the alloy prepared by the present invention has better heat resistance. The main reason is that the Fe content and plastic deformation amount used in the present invention are both low, and the drawing process does not cause a large number of dislocations to multiply, which is very beneficial to improving heat resistance.

Claims

1. A method for producing a low-cost super-heat-resistant aluminum alloy wire single filament, characterized by: Specifically, the following steps are included: (1) Material preparation: Weigh out the aluminum-iron master alloy and aluminum ingots according to the mass percentage of Fe: 0.8-1.2% and the balance of Al; (2) Smelting: The aluminum-iron intermediate alloy and aluminum ingots are put into the furnace to melt and stirred until they are evenly mixed. During the stirring process, the temperature of the melt is maintained at 750-780℃. After removing the slag, it is kept at 700-720℃ for 60 minutes. (3) Al-Fe alloy rods were prepared by gas-assisted continuous casting and extrusion; (4) The alloy rod obtained in step (3) is cold-drawn to obtain a super heat-resistant aluminum alloy wire monofilament; In step (3), the specific process of gas-assisted continuous casting and extrusion is as follows: the molten metal flows into the extrusion wheel groove from the preheated funnel located above the extrusion wheel. Under the action of inert gas, the molten metal spreads out close to the wall of the extrusion wheel groove and begins to solidify. The solidified billet begins to accumulate after encountering the blockage and gradually enters the mold cavity, and finally is extruded from the mold hole to form an alloy rod.

2. The method for preparing low-cost ultra-heat resistant aluminum alloy wire monofilament according to claim 1, characterized in that: In step (3), the diameter of the funnel is 2-4 mm, and the funnel needs to be heated to 730-750℃ before pouring in the alloy melt.

3. The method for preparing low-cost ultra-heat resistant aluminum alloy wire monofilament according to claim 1, characterized in that: In step (3), the inert gas is nitrogen or argon, and the gas pressure is 0.10-0.18 MPa.

4. The method for preparing low-cost ultra-heat resistant aluminum alloy wire monofilament according to claim 1, characterized in that: In step (3), the rotation speed of the extrusion roller is 5-10 rpm.

5. The method for preparing low-cost ultra-heat resistant aluminum alloy conductor monofilament according to claim 1, characterized in that: In step (3), the preheating temperature of the extrusion die cavity is 300-350℃ and the die hole diameter is 9.5mm.

6. The method for preparing low-cost ultra-heat resistant aluminum alloy conductor monofilament according to claim 1, characterized in that: In step (4), the cold drawing is performed 4-6 times, and the total deformation is 78-82%.

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