Preparation method of low-cost super-heat-resistant aluminum alloy conductor monofilament

Abstract

The invention discloses a preparation method of a low-cost super-heat-resistant aluminum alloy conductor monofilament, and belongs to the technical field of wire and cable preparation. The super-heat-resistant aluminum alloy conductor monofilament is prepared through an alloy smelting-gas-assisted continuous casting extrusion-drawing process; according to the principle of the method, an alloy rod containing a nanoscale Al6Fe phase is obtained through gas-assisted continuous casting extrusion, the grain boundary density of the cross section of the alloy rod is increased through drawing so as to improve the strength, and finally the super-heat-resistant aluminum alloy wire monofilament is obtained. The production method provided by the invention has the advantages of low raw material cost, short production flow, low energy consumption and the like, and the production cost of the super-heat-resistant aluminum alloy conductor monofilament can be remarkably reduced.

Description

Technical Field

[0001] The invention relates to a method for preparing a low-cost super-heat-resistant aluminum alloy conductor monofilament, belonging to the technical field of wire and cable preparation. Background Art

[0002] Since Harrington discovered in 1949 that the Zr element can 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, super heat-resistant aluminum alloy conductors have a higher heat resistance level, with a maximum allowable continuous operating temperature of more than 210°C and a transmission capacity more than twice that of ordinary hard aluminum wires. They are an important direction for the development of heat-resistant aluminum alloy conductors in the future. However, it is worth noting that in the preparation process of such conductors, in order to fully precipitate the Zr element dissolved in the aluminum matrix, long-term heat treatment is usually required. The low production efficiency has greatly increased the production cost, causing the price of such conductors to reach more than three times that of ordinary hard aluminum wires, which restricts their promotion and application.

[0003] Fe is the most common impurity element in aluminum alloys. During equilibrium solidification, the Al3Fe phase formed by Fe and Al is often in the form of coarse needles or needle flakes, which will reduce the strength and toughness of the alloy. However, if the cooling rate of the alloy melt is increased, the iron-containing phase will become a dispersed Al6Fe phase, which can significantly improve the mechanical properties of the alloy. In addition, the Al6Fe phase has good stability below 300°C, and the extremely low solid solubility of Fe in the aluminum matrix is ​​conducive to obtaining higher conductivity, making Al-Fe alloys promising for use in super-heat-resistant aluminum alloy wires.

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

[0005] Patent CN202311757716.1 proposes a method for preparing high-strength and high-conductivity Al-Fe alloy wires, which uses a new non-equilibrium solidification technology - gas-assisted continuous casting and extrusion to refine the iron-rich phase to improve the strength level of the alloy. However, it is worth noting that in order to obtain excellent mechanical properties, the patent uses a higher Fe content (1-2%) and a larger plastic deformation (≥91%), which will inevitably sacrifice the material's electrical conductivity or heat resistance, making it difficult to meet the current standard's comprehensive requirements for super-heat-resistant wire strength, conductivity and heat resistance. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a low-cost super heat-resistant aluminum alloy wire monofilament, which specifically comprises the following steps:

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

[0008] (2) Melting: Place the aluminum-iron master alloy and aluminum ingot into a furnace for melting and stirring until the mixture is uniform. During the stirring process, the melt temperature is maintained at 750-780°C. Finally, the melt temperature is maintained at 700-720°C for 60 minutes.

[0009] (3) Preparation of Al-Fe alloy rods 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 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 speed of the extrusion wheel 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° C., and the die hole diameter is 9.5 mm.

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

[0016] The principle of the present invention is to obtain an alloy rod containing a nano-scale Al6Fe phase by gas-assisted continuous casting and extrusion, and to increase the grain boundary density of the alloy rod cross section by drawing to improve the strength, and finally obtain a super heat-resistant aluminum alloy wire monofilament.

[0017] Beneficial effects of the present invention:

[0018] (1) The nanoscale Al6Fe phase in the alloy is conducive to obtaining higher strength; the present invention has a faster cooling rate during the entire solidification process of the alloy melt, and nanoscale Al6Fe phases are formed at the grain boundaries and in the grains. A large number of evenly distributed hard particles have a strong pinning effect on dislocations, and the strengthening effect is significant.

[0019] (2) The excellent high-temperature stability of the Al6Fe phase can ensure the heat resistance of the single wire; the extremely low solid solubility and diffusion coefficient of Fe in aluminum ensure that the morphology and size of the nanoscale Al6Fe phase in the alloy remain unchanged after heat treatment at 300℃ / 10h, which can fully meet the test of super-heat-resistant wires at 280℃ / 1h.

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

[0021] (4) The tensile strength of the Al-Fe alloy wire monofilament prepared by the present invention exceeds 160 MPa, and the electrical conductivity at 20°C exceeds 60.1% IACS. At the same time, after heat exposure at 280°C / 1h, the tensile strength residual rate can reach more than 91%, which fully meets the requirements of the current standards for super heat-resistant aluminum alloy wire monofilaments.

[0022] (5) The present invention uses Fe instead of Zr, and the raw material cost is low; it eliminates the need for long-term heat treatment, has a short process flow, and has low energy consumption and processing cost: Therefore, the cost of preparing the alloy monofilaments according to the present invention is much lower than the cost of existing super-heat-resistant aluminum alloy monofilaments, which is conducive to promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flow chart of a method for preparing a low-cost super-heat-resistant aluminum alloy wire monofilament is provided;

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

[0025] In the figure: 1-funnel; 2-melt; 3-extrusion wheel; 4-extrusion wheel groove; 5-mold cavity; 6-mold; 7-extrusion rod; 8-injection device. DETAILED DESCRIPTION

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

[0027] The device used in the embodiment 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-jet device; the smelted metal melt 2 flows out from the preheated funnel 1 located above the extrusion wheel 3 to the extrusion wheel groove 4, and the jet device 8 above the extrusion wheel groove sprays inert gas. Under the action of the inert gas, the melt spreads closely 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 finished alloy rod 7.

[0028] Example 1

[0029] The present invention relates to a method for preparing a low-cost super-heat-resistant aluminum alloy wire monofilament, comprising the following steps:

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

[0031] (2) Melting: Place the aluminum-iron master alloy and aluminum ingot into a furnace for melting and stirring until the mixture is uniform. During the stirring process, the melt temperature is maintained at 760°C. Finally, the melt is kept at 700°C for 60 minutes to complete the melting.

[0032] (3) Preparation of Al-Fe alloy rods 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, and an inert gas (nitrogen gas, gas pressure is 0.15 MPa) 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 metal thin layer. Under the action of the extrusion wheel (rotation speed is 5 rpm) and the plug, the metal thin layer on the wheel groove wall continuously enters the mold and accumulates, and then is extruded from the mold hole to form an alloy rod; the funnel preheating temperature is 740°C, and the mold hole diameter is 9.5 mm.

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

[0034] Example 2

[0035] The present invention relates to a method for preparing a low-cost super-heat-resistant aluminum alloy wire monofilament, comprising the following steps:

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

[0037] (2) Melting: The aluminum-iron master alloy and aluminum ingot are placed in a furnace for melting and stirred until the mixture is uniform. During the stirring process, the melt temperature is maintained at 750°C. Finally, the melt is kept at 710°C for 60 minutes to complete the melting.

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

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

[0040] Example 3

[0041] The present invention relates to a method for preparing a low-cost super-heat-resistant aluminum alloy wire monofilament, comprising the following steps:

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

[0043] (2) Melting: Place the aluminum-iron master alloy and aluminum ingot into a furnace for melting and stirring until the mixture is uniform. During the stirring process, the melt temperature is maintained at 780°C. Finally, the melt is kept at 720°C for 60 minutes to complete the melting.

[0044] (3) Preparation of Al-Fe alloy rods 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, and an inert gas (nitrogen gas with a gas pressure of 0.18 MPa) 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 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 mold hole to form an alloy rod; the funnel preheating temperature is 750°C and the mold hole diameter is 9.5 mm.

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

[0046] Comparative Example 1

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

[0048] (2) Melting: Place the aluminum-iron master alloy and aluminum ingot into a furnace for melting and stirring until the mixture is uniform. During the stirring process, the melt temperature is maintained at 740°C. Finally, the melt is kept at 720°C for 60 minutes to complete the melting.

[0049] (3) Preparation of Al-Fe alloy rods 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, and an inert gas (nitrogen gas, gas pressure is 0.4 MPa) 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 metal thin layer. Under the action of the extrusion wheel (rotation speed is 10 rpm) and the plug, the metal thin layer on the wheel groove wall continuously enters the mold and accumulates, and then is extruded from the mold hole to form an alloy rod; the funnel preheating temperature is 820°C, and the mold hole diameter is 10 mm.

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

[0051] (5) The alloy wire obtained in step (4) was subjected to a heat treatment at 200°C for 3 h to obtain an Al-Fe alloy monofilament. After heat exposure at 280°C for 1 h, the tensile strength retention rate was 70%.

[0052] By comparing Examples 1, 2, and 3 with Comparative Example 1, it can be seen that the alloy prepared in the present invention has more excellent heat resistance. The main reason is that the Fe content and plastic deformation 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 the heat resistance.

Claims

1. A method for preparing a low-cost super-heat-resistant aluminum alloy wire monofilament, characterized in that: The specific steps include: (1) Material preparation: weigh the aluminum-iron master alloy and aluminum ingot according to the mass percentage of Fe: 0.8-0.95% and the balance of Al; (2) Melting: Place the aluminum-iron master alloy and aluminum ingot into a furnace for melting and stirring until the mixture is uniform. During the stirring process, the melt temperature is maintained at 750-780°C. After slag removal, the melt temperature is maintained at 700-720°C for 60 minutes. (3) Preparation of Al-Fe alloy rods 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.

2. The method for preparing a low-cost super-heat-resistant aluminum alloy wire monofilament according to claim 1, characterized in that: In step (3), the specific process of gas-assisted continuous casting and extrusion is as follows: the smelted metal melt flows into the extrusion wheel groove from the preheated funnel located above the extrusion wheel. Under the action of the inert gas, the melt spreads out closely against the wall of the extrusion wheel groove and begins to solidify. After encountering a blockage, the solidifying billet begins to accumulate and gradually transfers into the die cavity, and is finally extruded from the die hole to form an alloy rod.

3. The method for preparing a low-cost super-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° C. before pouring the alloy melt.

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

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

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

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

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