Al-Fe-Mg-Cu series aluminum alloy for cable shielding and preparation method of Al-Fe-Mg-Cu series aluminum alloy

Abstract

The invention discloses an Al-Fe-Mg-Cu series aluminum alloy for cable shielding and a preparation method thereof.The preparation method comprises the steps that an improved 8000 series aluminum alloy serves as a base body, a melting furnace is used for heating an aluminum ingot to be in a liquid state, a proper amount of related elements are added to alloy the base body, and the aluminum alloy of the formula replaces copper to manufacture a cable shielding belt. The problem of copper consumption of a traditional copper shielding strip is effectively solved, and the purpose of saving copper resources is achieved; the problem that performance such as strength, elongation and conductivity of a common aluminum shielding tape are mutually restricted is effectively solved; the material is expected to become a low-cost cable shielding material, the raw material cost of the cable is greatly reduced, and the market competitiveness of the product is improved.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic shielding materials, specifically relating to an Al-Fe-Mg-Cu aluminum alloy for cable shielding and its preparation method. Background Technology

[0002] Cables are characterized by being labor-intensive, capital-intensive, and low in technology. Metal shielding tape is a necessary structure for medium and low-voltage power cables, providing electromagnetic pulse shielding. High-voltage cables primarily use corrugated aluminum sheaths, while medium and low-voltage cables mainly use copper tape. China's copper reserves are only about 26 million tons, insufficient to meet domestic industry production needs. In stark contrast, China has abundant aluminum reserves, approximately 2.7 billion tons. Using aluminum to produce shielding tape to replace existing copper products can significantly reduce copper consumption, lower costs, and promote sustainable development in the industry.

[0003] Pure aluminum has advantages such as low density, low melting point, high plasticity, good corrosion resistance, and good electrical conductivity, but its strength is low and it cannot be directly used to manufacture shielding tape.

[0004] To ensure that the required tensile strength, elongation, and conductivity are met in practical applications, alloying methods are needed to improve these properties. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide an Al-Fe-Mg-Cu aluminum alloy for cable shielding.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an Al-Fe-Mg-Cu aluminum alloy for cable shielding, comprising elements Fe, Mg, Si, Cu, Re, B, and Al; wherein the aluminum alloy formulation is composed of the following mass percentages: 1.0-1.7% Fe, 0.2-0.7% Mg, less than 0.08% Si, 0.6-1.3% Cu, 0.1-0.2% Re, 0.03-0.35% B, with the balance being Al to make up to 100%.

[0009] As a preferred embodiment of the Al-Fe-Mg-Cu series aluminum alloy for cable shielding described in this invention, wherein: the element Al is derived from the aluminum matrix, and the aluminum matrix is ​​a modified 8000 series alloy with a basic conductivity of 60% IACS.

[0010] As a preferred embodiment of the Al-Fe-Mg-Cu series aluminum alloy for cable shielding described in this invention, wherein the elements Fe, Mg, Si, Cu, Re, and B are derived from intermediate alloy ingots doped with the corresponding metal elements.

[0011] As a preferred embodiment of the Al-Fe-Mg-Cu aluminum alloy for cable shielding described in this invention, the base aluminum in the intermediate alloy ingot is Al99.7E.

[0012] As a preferred embodiment of the Al-Fe-Mg-Cu aluminum alloy for cable shielding described in this invention, the aluminum alloy formulation comprises the following mass percentages: 1.0-1.7% Fe, 0.2-0.7% Mg, less than 0.08% Si, 0.6-1.3% Cu, 0.1-0.2% Re, 0.03-0.35% B, with the balance being Al to bring the total to 100%.

[0013] As a preferred embodiment of the Al-Fe-Mg-Cu aluminum alloy for cable shielding described in this invention, the aluminum alloy formulation comprises the following mass percentages: 1.0-1.7% Fe, 0.2-0.7% Mg, less than 0.08% Si, 0.6-1.3% Cu, 0.1-0.2% Re, 0.03-0.35% B, with the balance being Al to bring the total to 100%.

[0014] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing Al-Fe-Mg-Cu aluminum alloys for cable shielding.

[0015] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing an Al-Fe-Mg-Cu aluminum alloy for cable shielding, comprising,

[0016] Matrix material selection: An improved 8000 series aluminum alloy was selected as the matrix material;

[0017] Set the melting furnace temperature to 750℃ and heat the aluminum ingots to a liquid state;

[0018] Preparation of aluminum alloys: Additives are added in the form of aluminum-additive master alloys in the trough between the holding furnace or the melting furnace, and the base aluminum of the aluminum-additive master alloy ingot is Al99.7E;

[0019] Stirring: Manual stirring and electromagnetic stirring are used. First, after pressing the aluminum liquid into the intermediate alloy ingot, manual stirring is used to homogenize it. Then, electromagnetic stirring is used in the holding furnace in the left-hand, right-hand, front and back directions to further ensure the uniformity of its composition.

[0020] Degas and remove slag from the furnace, then add a surface covering agent;

[0021] After degassing and filtration outside the furnace, an Al-Fe-Mg-Cu series aluminum alloy for cable shielding is obtained.

[0022] Beneficial effects of this invention:

[0023] (1) The present invention uses a new type of aluminum alloy material to produce cable shielding tape, which can replace the existing copper cable shielding tape and greatly reduce copper resource consumption.

[0024] (2) The present invention improves the aluminum matrix material by using an alloying method, thereby improving the tensile strength, elongation and conductivity of the shielding strip in actual use. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0026] Figure 1 This is a diagram of an aluminum melting furnace.

[0027] Figure 2 This is a metallographic diagram of the aluminum alloy.

[0028] Figure 3 This is the X-ray diffraction pattern of the aluminum alloy.

[0029] Figure 4 This is a graph showing the tensile strength and elongation of an aluminum alloy.

[0030] Figure 5 This is a morphological image of a tensile specimen of aluminum alloy.

[0031] Figure 6 This is a scanning electron microscope (SEM) image of the fracture surface of an aluminum alloy. Detailed Implementation

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0033] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0034] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0035] Example 1

[0036] A novel Al-Fe-Mg-Cu aluminum alloy formulation for cable shielding and its preparation method, comprising the following steps:

[0037] Step 1: Selection of matrix material

[0038] The aluminum ingots used were grade A199.7E (purchased from Pingguo Aluminum Plant in Guangxi), characterized by low total content of Ti+V+Mn+Cr and low Si content.

[0039] The 8000 series aluminum alloy grade A199.7E has the following standard composition as shown in Table 1.

[0040] Chemical composition (mass fraction) of Table 1A199.7E

[0041]

[0042] The second step is to set the melting furnace temperature to 750℃ and heat the aluminum ingots to a liquid state; after heating, it is necessary to keep them at a constant temperature.

[0043] Step 3: Preparation of aluminum alloy

[0044] pass Figure 1 The aluminum melting furnace is prepared by means of a manual stirring device 100, a metal cage 200, a melting furnace 300 and an electromagnetic stirrer 400. The manual stirring device 100 is installed in the cavity of the melting furnace 300, the metal cage 200 is movably installed in the cavity of the melting furnace 300, and the magnetic stirrer 400 is installed at the bottom of the melting furnace 300.

[0045] An appropriate amount of intermediate alloy ingots, containing aluminum-iron, aluminum-magnesium, aluminum-copper, aluminum rare earth, and aluminum-boron, is added. The intermediate alloy is then rapidly pressed into the molten aluminum using an alumina metal cage (200) to obtain an aluminum alloy.

[0046] The intermediate alloy ingot contains 4% Fe aluminum and the base aluminum grade is A199.7E. Low-carbon iron is used, which can increase strength and reduce conductivity less.

[0047] The intermediate alloy ingot contains 10% Mg aluminum and the base aluminum grade is A199.7E, which can increase strength and reduce conductivity.

[0048] The intermediate alloy ingot contains 10% Cu aluminum and copper, with the base aluminum grade being A199.7E and using No. 2 copper to increase strength.

[0049] The aluminum rare earth composition in the intermediate alloy ingot is 10% Re. The base aluminum grade is A199.7E, which is a mixed rare earth element with La as the main component and the grade is 194020A. It can improve conductivity and processing performance. The chemical composition of the mixed rare earth metals used is shown in Table 2.

[0050] Table 2 Chemical composition of rare earth metals of grade 194020 (GB / T 4153-2008)

[0051]

[0052]

[0053] The intermediate alloy ingot contains 3% boron (B) and uses aluminum grade A199.7E as the base alloy. This refines the grain size, increases strength, and reduces the detrimental effects of trace elements (Ti+V+Mn+Cr) on conductivity.

[0054] Step 4: Stir

[0055] After adding the intermediate alloy, a manual stirring device 100 is first used to homogenize it. Then, an electromagnetic stirrer 400 with left-hand, right-hand, and forward and backward motions is used in the holding furnace to further ensure the uniformity of its composition. A surface covering agent is added to the surface of the aluminum liquid and left to stand.

[0056] Step 5: Degassing and slag removal inside the furnace;

[0057] Step 6: Degas and filter outside the furnace, then remove from the furnace to obtain alloy ingots.

[0058] In the third step, the aluminum alloy formulation for the strip design is shown in Table 3:

[0059] Table 3 Aluminum alloy formulations for strip design

[0060]

[0061] The boron content in the aluminum-boron master alloy used is ≥3%B, and the raw aluminum used is A199.7E.

[0062] According to standard GB / T1196-2017, Ti+V+Mn+Cr ≤ 0.02%. This invention requires Ti+V+Mn+Cr ≤ 0.01%. If the 0.01% requirement is not met, the boron content in the aluminum alloy formulation should be controlled at 0.007%, as per Table 3. In the third step, samples of the aluminum liquid with added elements are taken for composition analysis. If the composition is unqualified, it needs to be adjusted quickly.

[0063] It can be seen that using both manual and electromagnetic stirring equipment can improve the melting effect of aluminum ingots, and prolonged stirring is particularly important for adjusting the composition and improving its uniformity. Using a metal cage 200 to quickly press the intermediate alloy ingot can also improve the uniformity of added elements.

[0064] Example 2

[0065] (1) An aluminum alloy was prepared according to the process conditions in Example 1 and then made into an aluminum alloy strip. The specific composition of the aluminum alloy strip is shown in Table 4.

[0066] Table 4. Element content (mass fraction wt%) of aluminum alloy strip

[0067]

[0068]

[0069] (2) Aluminum alloy strip processing technology, including the following steps:

[0070] Step 1: Milling the surface

[0071] For machining aluminum alloys, the milling parameters are: minimum point 6-8mm / single side, tool mark depth ≤0.1mm, and the surface after milling is smooth, without cracks or inclusions.

[0072] The second step involves heating the aluminum alloy twice to homogenize it.

[0073] In the first stage, the furnace gas is set at 510℃. When the ingot temperature reaches 495℃, it is held for 4 hours before proceeding to the second stage.

[0074] In the second stage, the furnace gas is set to 600℃. When the ingot temperature reaches 585℃, it is held for 8 hours before proceeding to the third stage.

[0075] In the third stage, the heater is stopped. When the ingot temperature reaches 510℃, the furnace gas is set to 520℃ and held for 2 hours before being rolled out.

[0076] The third step is to perform hot rolling (initial rolling).

[0077] Target Specifications:

[0078] Rolling temperature: 470~490℃

[0079] Final rolling temperature 270–290℃

[0080] The rolling process is shown in Table 5.

[0081] Table 5

[0082]

[0083]

[0084] Step 4: Perform intermediate annealing. Intermediate annealing thickness: 0.8mm, 1.0mm.

[0085] Intermediate annealing sampling: 0.8mm and 1.0mm head samples (to determine the temperature for intermediate annealing) Intermediate annealing process:

[0086] Target metal temperature: 320℃~350℃, hold for 2 hours;

[0087] 200℃×2h (evaporation and oil removal) + 420℃×3h + 360℃×3h

[0088] Step 5: Perform cold rolling (finish rolling)

[0089] Target specifications for cold-rolled finished products: 0.1 / 0.12±0.005×670+3-0×Cmm

[0090] The rolling process is shown in Table 6.

[0091] Table 6

[0092]

[0093] Step 6: Anneal the finished product.

[0094] Target temperature 250℃~300℃

[0095] 180℃×2h+220℃×2h+275℃×6h

[0096] Step 7, Testing

[0097] The tensile strength was tested to be 165-170 MPa, the elongation was 15-19%, and the bending performance was tested to be repeated 12 times.

[0098] (3) The metallographic structure of the aluminum alloy under different treatment states was determined, and the results are shown in the figure. Figure 2 ,in, Figure 2 (a) is a metallographic diagram of the aluminum alloy before casting. Figure 2 (b) is a metallographic diagram of the hot-rolled aluminum alloy. Figure 2 (c) Metallographic structure diagram of aluminum alloy strip.

[0099] It can be seen that the main metallographic structure of the aluminum alloy before casting is aluminum alloy α solid solution, and no obvious eutectic structure appears in the aluminum alloy. The metallographic structure of the aluminum alloy and the product after hot rolling is not significantly different except for a certain degree of banded structure.

[0100] (3) XRD microstructure

[0101] X-ray diffraction analysis of the aluminum alloy was performed, and the spectrum is shown below. Figure 3 As shown.

[0102] Depend on Figure 3 It can be seen that the microstructure of the aluminum alloy strip before hot rolling and casting is mainly α solid solution, and no obvious second phase microstructure was found.

[0103] Example 3

[0104] The mechanical properties of the aluminum alloy strip prepared in Example 2 were measured.

[0105] Tensile tests were conducted on aluminum alloy strips of different sizes, and the results are shown in Table 2.

[0106] Table 2 Mechanical property parameters of aluminum alloy strip

[0107]

[0108]

[0109] As shown in Table 2, the average strength of the aluminum alloy strip is 143 MPa, and the average elongation is 15.8%. The mechanical tensile properties of aluminum alloy strips of different sizes are relatively stable and there are no significant differences. The elongation of the aluminum alloy strips is higher than 12%.

[0110] Example 4

[0111] Mechanical properties of aluminum alloy strips at different annealing temperatures:

[0112] Under the process conditions of Example 3, the mechanical properties of the aluminum alloy strip at different annealing temperatures were measured. Table 3 shows the mechanical property parameters of the aluminum alloy strip at different annealing temperatures. The tensile strength and elongation curves of the aluminum alloy strip at different annealing temperatures are shown in the figure. Figure 4 .

[0113] As shown in Table 3, as the annealing temperature increases from 100℃ to 360℃, the tensile strength of the aluminum strip in the formulation gradually decreases from 280MPa to 122MPa, while the elongation first increases and then decreases. When the annealing temperature is 320℃, the elongation of the aluminum strip in the formulation reaches the maximum value of 16.3%.

[0114] Table 3 Mechanical property parameters of aluminum alloy strip at different heat treatment temperatures

[0115]

[0116]

[0117] Example 5

[0118] Tensile fracture morphology

[0119] The appearance morphology of the aluminum alloy strip tensile specimen is as follows Figure 5 As shown in the figure, the tensile fracture surface of the specimen generally exhibits the characteristics of a typical aluminum alloy plate tensile fracture. For the aluminum alloy strip, the fracture surface has an angle of approximately 45°, exhibiting a typical ductile fracture morphology. It should be noted that due to the relatively thin thickness of the aluminum alloy strip, the fracture surface is prone to appear outside the scribed lines, thus causing a certain degree of deviation.

[0120] SEM microscopy of tensile fracture surface of aluminum alloy strip as follows Figure 6 As shown in the figure, the tensile fracture surfaces of the aluminum alloy strips all exhibit typical dimple structures under scanning electron microscopy.

[0121] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An Al-Fe-Mg-Cu aluminum alloy for cable shielding, characterized in that: include, The elements are Fe, Mg, Si, Cu, Re, B, and Al; among them, The aluminum alloy formulation consists of the following mass percentages: 1.0-1.7% Fe, 0.2-0.7% Mg, less than 0.08% Si, 0.6-1.3% Cu, 0.1-0.20% Re, 0.03-0.35% B, with the balance being Al to bring the total to 100%.

2. The Al-Fe-Mg-Cu aluminum alloy for cable shielding as described in claim 1, characterized in that: The element Al is derived from an aluminum matrix, which is a modified 8000 series alloy with a basic conductivity of 60% IACS.

3. The Al-Fe-Mg-Cu aluminum alloy for cable shielding as described in claim 2, characterized in that: The elements Fe, Mg, Si, Cu, Re, and B are derived from intermediate alloy ingots doped with the corresponding metallic elements.

4. The Al-Fe-Mg-Cu aluminum alloy for cable shielding as described in claim 3, characterized in that: The base aluminum in the intermediate alloy ingot is Al99.7E.

5. The Al-Fe-Mg-Cu aluminum alloy for cable shielding as described in claim 1 or 2, characterized in that: The aluminum alloy formulation consists of the following mass percentages: 1.0-1.7% Fe, 0.2-0.7% Mg, less than 0.08% Si, 0.6-1.3% Cu, 0.1-0.2% Re, 0.03-0.35% B, with the balance being Al to bring the total to 100%.

6. The Al-Fe-Mg-Cu aluminum alloy for cable shielding as described in claim 5, characterized in that: The aluminum alloy formulation consists of the following mass percentages: 1.0-1.7% Fe, 0.2-0.7% Mg, less than 0.08% Si, 0.6-1.3% Cu, 0.1-0.2% Re, 0.03-0.35% B, with the balance being Al to bring the total to 100%.

7. The method for preparing the Al-Fe-Mg-Cu aluminum alloy for cable shielding as described in any one of claims 1 to 6, characterized in that: include, Matrix material selection: An improved 8000 series aluminum alloy was selected as the matrix material; Set the melting furnace temperature to 750℃ and heat the aluminum ingots to a liquid state; Preparation of aluminum alloys: Additives are added in the form of aluminum-additive master alloys in the trough between the holding furnace or the melting furnace, and the base aluminum of the aluminum-additive master alloy ingot is Al99.7E; Stirring: Manual stirring and electromagnetic stirring are used. First, after pressing the aluminum liquid into the intermediate alloy ingot, manual stirring is used to homogenize it. Then, electromagnetic stirring is used in the holding furnace in the left-hand, right-hand, front and back directions to further ensure the uniformity of its composition. Degas and remove slag from the furnace, then add a surface covering agent; After degassing and filtration outside the furnace, an Al-Fe-Mg-Cu series aluminum alloy for cable shielding is obtained.

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