Highly conductive and ductile aluminum alloy profile and method of production thereof

Abstract

The application provides an aluminum alloy profile with high conductivity and high toughness and a production method thereof, and the aluminum alloy profile has the following components in mass fraction: Si: 0.08%-0.12%, Fe+Cu: 0.8%-1.1%, B: 0.03%-0.05%; wherein (Ti+Cr+V) is less than or equal to 0.006%, the total content of other impurity elements is less than or equal to 0.05%, and the balance is Al. The application selects reasonable alloy element ratio, follows the extrusion process, such as the process of the temperature of a casting bar and the extrusion speed, and ensures that the alloy performance meets the requirements in view of the fact that the aluminum alloy extrusion material needs to be drawn subsequently. The product obtained by the application does not need subsequent annealing treatment, and can obtain the aluminum alloy material with high conductivity and high toughness while meeting certain strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aluminum alloy conductive materials, in particular to a high-conductivity and high-toughness aluminum alloy profile and a production method thereof. BACKGROUND

[0002] In recent years, aluminum alloys are increasingly used in the field of conductive materials. For example, the inductive plate arranged on the maglev track needs to have high conductivity. These materials not only meet the requirement of high conductivity, but also have certain requirements for strength. Higher toughness also has certain advantages for subsequent processing. Materials with high strength, high toughness, and high conductivity can effectively improve the efficiency of electric energy conversion, thereby effectively reducing the resistance of the maglev vehicle, and thus improving the speed of the maglev vehicle and saving energy.

[0003] Patent CN 111575546 A discloses a production method of a track inductive plate for a high-speed constant-conductivity maglev train. The inductive plate for the maglev train is made of an aluminum alloy conductive material with a conductivity of ≥59.6% IACS. At present, the conductivity of the aluminum alloy conductive material for the maglev vehicle is basically not higher than 60% IACS. Therefore, the development of high-strength, high-toughness, and higher-conductivity materials has become the research focus of the industry. SUMMARY

[0004] The technical task of the present application is to solve the problems of the prior art, and to provide a high-conductivity and high-toughness aluminum alloy profile and a production method thereof. The present application selects a reasonable alloy element ratio, controls the total amount of (Fe+Cu) elements, adds 0.03%-0.05% B elements, controls the total content of impurity elements ≤0.05%, and optimizes the extrusion process, such as the temperature of the casting rod, the extrusion speed, etc. The aluminum alloy extrusion material is subjected to subsequent drawing treatment to ensure that the alloy performance meets the requirements. The present application does not require subsequent annealing treatment, and can obtain an aluminum alloy profile material that meets certain strength, has high conductivity, and has high toughness.

[0005] The technical solution adopted by the present application to solve the technical problems is: a high-conductivity and high-toughness aluminum alloy profile, the composition of the aluminum alloy profile is, in mass fraction, Si: 0.08%-0.12%, Fe+Cu: 0.8%-1.1%, B: 0.03%-0.05%; wherein (Ti+Cr+V)≤0.006%, the total content of other impurity elements ≤0.05%, and the balance is Al.

[0006] Further, in the aluminum alloy profile, the content of Fe is greater than twice the content of Cu.

[0007] The production method of the above-mentioned high-conductivity and high-toughness aluminum alloy profile includes the following steps:

[0008] Melting and casting: after raw materials are melted, aluminum alloy cast bars are casted;

[0009] Extrusion: the temperature of the extrusion die is 350-370 DEG C, the heating temperature of the aluminum alloy cast bar is 270-310 DEG C, the extrusion speed is 5-7 m / min, and water cooling is used after extrusion;

[0010] Drawing treatment: the profile after cooling is drawn, and the drawing amount is 4%-7%.

[0011] Further, the melting and casting adopts a conventional semi-continuous casting method, and the specific parameter adjustment depends on the selection of the components and the equipment parameters.

[0012] Further, the melting and casting specifically includes: heating a smelting furnace to 600-700 DEG C, putting pure Al, adding Al-Cu and Al-Fe intermediate alloys after the pure Al is melted, adding Al-B intermediate alloy after complete melting, increasing the temperature of the smelting furnace to 730-760 DEG C, fully melting, then uniformly stirring, degassing refining, deslagging, then semi-continuous casting, pouring temperature is 740-750 DEG C, casting speed is 140-150 mm / min, and the temperature difference of the inlet and outlet of the cooling water is 27 DEG C.

[0013] Further, all raw materials are preheated at 140-160 DEG C before melting and casting to remove the attached water vapor.

[0014] Further, the electrical conductivity of the aluminum alloy profile after the drawing treatment is greater than 61.0% IACS, the yield strength is greater than 80 MPa, the tensile strength is greater than 110 MPa, and the elongation is greater than 28%.

[0015] The component design principle of the application is:

[0016] Cr, Mn, Ti, Mg, Cu have a greater influence on the electrical conductivity of the aluminum alloy, the higher the content, the lower the electrical conductivity (known from Figure 1 ). Si, Zn and Fe elements have little effect on the electrical conductivity of the aluminum alloy. Therefore, for high-conductivity aluminum alloy, the preferred strengthening elements are Si, Fe and Zn to ensure the strength of the alloy. The Si content is 0.08%-0.12% to improve the Fe phase in the matrix and enhance the strength, but excessive addition will cause free Si to exist in the Al matrix, resulting in performance degradation, so the content should be strictly controlled within the component design range. At the same time, the solid-solution Cu has a greater influence on the electrical conductivity of the aluminum alloy, while the Cu existing in the second phase has little effect on the electrical conductivity of the alloy, so the content of Fe+Cu should be strictly controlled to 0.8%-1.1% (the content of Fe should be more than twice the content of Cu) to ensure the strength and obtain better electrical conductivity. In addition, to ensure the electrical conductivity of the alloy, the total content of impurity elements should be ≤0.05%.

[0017] Figure 2 The relationship between B element and the total content of (Ti+Cr+V) in the alloy is shown in the figure. As can be seen from the figure, when no B element is added, the total content of (Ti+Cr+V) in the alloy is the highest, reaching 0.011%. With the addition of B element, the content gradually decreases. When the addition amount of B element reaches 0.05%, the total content of (Ti+Cr+V) in the alloy does not continue to decrease, and is maintained at a low level, which is 0.004% at this time. After adding B element, the total content of (Ti+Cr+V) decreases, mainly because the Gibbs free energy of the boride formed by (Ti+Cr+V) and B is larger than that of AlB2, so the boron reaction can be preferentially carried out. At this time, CrB, CrB2, TiB, TiB2, VB, VB2, V2B2 and other borides are preferentially formed, which are removed from the melt in the slag removal stage. Therefore, adding a certain amount of B element can improve the electrical conductivity of the alloy.

[0018] Compared with the prior art, the beneficial effects of the present application are:

[0019] 1. The present application obtains an aluminum alloy material with an electrical conductivity of 61.0% IACS or more by optimizing the alloy element ratio and adding trace element B.

[0020] 2. The present application strictly controls the heating temperature of the aluminum alloy casting rod to be 270-310℃, the extrusion speed to be 5-7m / min, and then performs 4%-7% deformation drawing treatment to obtain an aluminum alloy material with surface metal luster and no bamboo joint, and the mechanical properties reach a yield strength of 80MPa, a tensile strength of 110MPa, and an elongation of 28% or more.

[0021] 3. The profile does not need to be heat treated in the production process, which can effectively save the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the influence diagram of alloy elements on the electrical conductivity of aluminum alloy;

[0023] Figure 2 is the relationship between B element and the total content of (Ti+Cr+V) in the aluminum alloy;

[0024] Figure 3 is the influence diagram of casting rod heating temperature on the profile surface;

[0025] Figure 4 is the influence diagram of extrusion speed on the profile surface. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0027] The present application provides a high-conductivity and high-toughness aluminum alloy profile, which comprises, in mass fraction, Si: 0.08%-0.12%, Fe+Cu: 0.8%-1.1%, B: 0.03%-0.05%; wherein (Ti+Cr+V)≤0.006%, the total content of impurity elements is ≤0.05%, and the balance is Al.

[0028] In the aluminum alloy profile, the content of Fe is greater than 2 times the content of Cu in mass fraction.

[0029] The production method of the high-conductivity and high-toughness aluminum alloy profile comprises the following steps:

[0030] Melting and casting: after the raw materials are melted, aluminum alloy cast bars are cast, the melting and casting adopts a conventional semi-continuous casting method, and the specific parameters are adjusted according to the selection of the composition and the equipment parameters. All the raw materials are preheated at 140-160 ℃ to remove the water vapor attached thereto; the melting furnace is heated to 600-700 ℃, pure Al is put in, after the pure Al is collapsed, Al-Cu and Al-Fe intermediate alloys are added, after complete melting, Al-B intermediate alloy is added, the temperature of the melting furnace is increased to 730-760 ℃, and after sufficient melting, uniform stirring, degassing refining, deslagging, semi-continuous casting is performed, the casting temperature is 740-750 ℃, the casting speed is 140-150 mm / min, and the temperature difference between the inlet and outlet of the cooling water is 27 ℃.

[0031] Extrusion: the temperature of the extrusion die is 350-370 ℃, the heating temperature of the aluminum alloy cast bar is 270-310 ℃, the extrusion speed is 5-7 m / min, and water cooling is adopted after extrusion;

[0032] Drawing treatment: the profile after cooling is subjected to drawing treatment, and the drawing amount is 4%-7%. The aluminum alloy profile adopts a conventional drawing process to straighten, ensure the size and eliminate internal stress. The drawing treatment of the present application increases the hardening degree of the product and improves the strength.

[0033] The present application selects reasonable alloy element ratio, strictly controls the total amount of (Fe+Cu) elements, adds 0.03%-0.05% of B elements, controls (Ti+Cr+V)≤0.006%, the total content of impurity elements is ≤0.05%, and strictly follows the extrusion process, such as the temperature of the cast bar and the extrusion speed. The aluminum alloy extrusion material needs to be subjected to drawing treatment subsequently to ensure that the alloy performance meets the requirements. The product obtained by the present application does not need subsequent annealing treatment, and can obtain an aluminum alloy material which meets certain strength, has high conductivity and high toughness. The composition of the aluminum alloy profile and the preparation parameters are shown in the following examples.

[0034] Example 1

[0035] The aluminum alloy profile composition, by mass fraction, is as follows: Si: 0.09%, (Fe+Cu): 1.0%, B: 0.04%, of which Fe: 0.8%, Cu: 0.2%; (Ti+Cr+V) ≤ 0.006%, total content of other impurities ≤ 0.05%, and the balance is Al.

[0036] The above-mentioned aluminum alloy profile production methods include:

[0037] Casting: The rod is cast using a conventional semi-continuous casting method.

[0038] Extrusion: The extrusion die temperature is 350℃, the aluminum alloy cast rod heating temperature is 270℃, the extrusion speed is 7m / min, and water cooling is used after extrusion.

[0039] Drawing process: 6% stretching.

[0040] Example 2

[0041] The aluminum alloy profile composition, by mass fraction, is as follows: Si: 0.08%, (Fe+Cu): 0.8%, B: 0.03%, of which Fe: 0.55%, Cu: 0.25%; (Ti+Cr+V) ≤ 0.006%, total content of other impurities ≤ 0.05%, and the balance is Al.

[0042] The above-mentioned aluminum alloy profile production methods include:

[0043] Casting: The rod is cast using a conventional semi-continuous casting method.

[0044] Extrusion: The extrusion die temperature is 350℃, the aluminum alloy cast rod heating temperature is 270℃, the extrusion speed is 7m / min, and water cooling is used after extrusion.

[0045] Drawing process: 6% stretching.

[0046] Example 3

[0047] The aluminum alloy profile composition, by mass fraction, is as follows: Si: 0.12%, (Fe+Cu): 1.1%, B: 0.05%, of which Fe: 0.75%, Cu: 0.35%; (Ti+Cr+V) ≤ 0.006%, total content of other impurities ≤ 0.05%, and the balance is Al.

[0048] The above-mentioned aluminum alloy profile production methods include:

[0049] Casting: The rod is cast using a conventional semi-continuous casting method.

[0050] Extrusion: The extrusion die temperature is 350℃, the aluminum alloy cast rod heating temperature is 270℃, the extrusion speed is 7m / min, and water cooling is used after extrusion.

[0051] Drawing process: 6% stretching.

[0052] Comparative Example 1

[0053] The aluminum alloy profile composition, by mass fraction, is as follows: Si: 0.09%, (Fe+Cu): 1.0%, B: 0.04%, of which Fe: 0.6%, Cu: 0.4%; (Ti+Cr+V) ≤ 0.006%, total content of other impurities ≤ 0.05%, and the balance is Al.

[0054] The above-mentioned aluminum alloy profile production methods include:

[0055] Melting and casting: Cast into a rod using conventional melting and casting process.

[0056] Extrusion: The extrusion die temperature is 350℃, the aluminum alloy cast rod heating temperature is 270℃, the extrusion speed is 7m / min, and water cooling is used after extrusion.

[0057] Drawing process: 6% stretching.

[0058] Comparative Example 2

[0059] The aluminum alloy profile composition, by mass fraction, is as follows: Si: 0.09%, (Fe+Cu): 1.0%, B: 0.04%, of which Fe: 0.4%, Cu: 0.6%; (Ti+Cr+V) ≤ 0.006%, total content of other impurities ≤ 0.05%, and the balance is Al.

[0060] The above-mentioned aluminum alloy profile production methods include:

[0061] Melting and casting: Cast into a rod using conventional melting and casting process.

[0062] Extrusion: The extrusion die temperature is 350℃, the aluminum alloy cast rod heating temperature is 270℃, the extrusion speed is 7m / min, and water cooling is used after extrusion.

[0063] Drawing process: 6% stretching.

[0064] Comparative Example 3

[0065] The aluminum alloy profile composition, by mass fraction, is as follows: Si: 0.09%, (Fe+Cu): 1.0%, B: 0.04%, of which Fe: 0.2%, Cu: 0.8%; (Ti+Cr+V) ≤ 0.006%, total content of other impurities ≤ 0.05%, and the balance is Al.

[0066] The above-mentioned aluminum alloy profile production methods include:

[0067] Melting and casting: Casting into rods using conventional melting and casting processes.

[0068] Extrusion: The extrusion die temperature is 350℃, the aluminum alloy cast rod heating temperature is 270℃, the extrusion speed is 7m / min, and water cooling is used after extrusion.

[0069] Drawing process: 6% stretching.

[0070] Mechanical and electrical properties of Examples 1-3 and Comparative Examples 1-3 were tested, and the results are shown in Table 1. When the total (Fe+Cu) content remained unchanged, but the Fe content was not greater than twice the Cu content, although the alloy strength remained basically unchanged, the increase in Cu content caused excessive Cu elements to dissolve in the matrix. Although the strength was improved, the alloy conductivity was severely reduced.

[0071] Table 1

[0072]

[0073] The profiles obtained after extrusion in Example 1 were subjected to drawing treatment with different stretching amounts. The results are shown in Table 2. After drawing, the alloy underwent work hardening. The yield strength increased continuously with the increase of the drawing amount, while the tensile strength only increased slightly. At the same time, the elongation began to decrease. When the drawing amount was 3%, the yield strength was low, only 70 MPa. When the drawing amount reached 8%, the yield strength was close to the tensile strength. The yield-to-tensile ratio of the material became higher, and the toughness decreased. When the material was subjected to stress exceeding its yield strength, it would break. In addition, excessively high drawing amounts are not easy to achieve in conventional extrusion-matched drawing equipment.

[0074] Table 2 Alloy properties under different drawing weights

[0075]

[0076] The cast rods obtained after melting and casting in Example 1 were subjected to extrusion treatment at different heating temperatures. The extrusion die temperature was 350°C, the aluminum alloy cast rod heating temperature was 270°C-350°C, the extrusion speed was 7 m / min, and water cooling was used after extrusion. Then, a drawing process was performed with a stretching amount of 6%. The effects of different cast rod heating temperatures on the profile surface are as follows: Figure 3 As shown, heating temperatures are 270℃ (3(a), 310℃ (3(b), 330℃ (3(c), 350℃ (3(d))). It can be seen that when the heating temperature of the cast rod is 270-310℃, the surface of the profile is smooth and has a metallic luster. When the heating temperature of the cast rod is 330℃, bamboo-like patterns begin to appear on the surface of the profile. When the heating temperature of the cast rod is 350℃, the bamboo-like patterns are more obvious and the spacing between the bamboo-like patterns becomes shorter.

[0077] The cast ingots obtained after melting and casting in Example 1 were subjected to extrusion treatment at different extrusion speeds. The extrusion die temperature was 350°C, the aluminum alloy cast ingot heating temperature was 270°C, and the extrusion speed was 7-9 m / min. Then, a drawing process was performed with a stretching amount of 6%. The effect of different extrusion speeds on the profile is as follows: Figure 4 As shown, 4(a) has an extrusion speed of 7 m / min, 4(b) has an extrusion speed of 8 m / min, and 4(c) has an extrusion speed of 9 m / min. It can be observed that when the extrusion speed is 7 m / min, the profile surface is smooth and has a metallic luster. Subsequently, as the extrusion speed continues to increase, bamboo-like patterns begin to appear on the profile surface, and the spacing between the bamboo-like patterns shortens.

[0078] The formation of bamboo-like patterns on profile surfaces is related to the flow characteristics of metal during the extrusion process, with the temperature during metal deformation being the dominant factor. High casting temperatures or excessively fast extrusion speeds will lead to excessively high temperatures. When the tensile stress on the metal surface exceeds the metal deformation temperature during extrusion, the extrusion pressure will cause plastic deformation of the surface metal, resulting in the surface metal becoming trapped during the extrusion process and thus forming bamboo-like patterns.

[0079] The above technical solutions illustrate the technical concept of the present invention, but should not be construed as limiting the scope of protection of the present invention. Any modifications or alterations made to the above technical solutions based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A method for producing a high-conductivity and high-toughness aluminum alloy profile, characterized in that: Includes the following steps: Melting and casting: The raw materials are melted and then cast into aluminum alloy rods; Extrusion: The extrusion die temperature is 350-370℃, the heating temperature of the aluminum alloy cast rod is 270-310℃, the extrusion speed is 5-7m / min, and water cooling is used after extrusion; Drawing treatment: The cooled profile is drawn with a stretch of 4%-7%; The composition of the aluminum alloy profile, by mass fraction, is: Si: 0.08%-0.12%, Fe+Cu: 0.8%-1.1%, B: 0.03%-0.05%; wherein the Fe content is greater than twice the Cu content, (Ti+Cr+V) ≤ 0.006%, the total content of other impurity elements ≤ 0.05%, and the balance is Al.

2. The method for producing a high-conductivity and high-toughness aluminum alloy profile according to claim 1, characterized in that: The casting process employs a conventional semi-continuous casting method, with specific parameter adjustments depending on the selection of the composition and equipment parameters.

3. The method for producing a high-conductivity and high-toughness aluminum alloy profile according to claim 1, characterized in that: The specific process of melting and casting is as follows: the melting furnace is heated to 600-700℃, pure Al is added, and after the pure Al collapses, Al-Cu and Al-Fe master alloys are added. After they are completely melted, Al-B master alloy is added, and the temperature of the melting furnace is raised to 730-760℃. After full melting, the mixture is stirred evenly, degassed and refined, and slag is removed. Then, semi-continuous casting is carried out at a casting temperature of 740-750℃, a casting speed of 140-150mm / min, and a cooling water inlet and outlet temperature difference of 27℃.

4. The method for producing a high-conductivity and high-toughness aluminum alloy profile according to claim 1, characterized in that: Before casting, all raw materials are preheated at 140-160℃ to remove any attached moisture.

5. The method for producing a high-conductivity and high-toughness aluminum alloy profile according to claim 1, characterized in that: The aluminum alloy profile after drawing treatment has a conductivity greater than 61.0% IACS, a yield strength greater than 80 MPa, a tensile strength greater than 110 MPa, and an elongation greater than 28%.

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