A method for producing an aluminum-clad magnesium composite rod

Abstract

This invention relates to the field of composite material preparation technology, and particularly to a method for preparing aluminum-clad magnesium composite rods. The specific steps are as follows: S1: Grinding and cleaning the surface of the magnesium alloy core rod; S2: Grinding and cleaning the inner wall and surface of the aluminum alloy tube; S3: Placing the magnesium alloy core rod obtained in step S1 into the aluminum alloy tube obtained in step S2; S4: Feeding the initial billet assembled in step S3 into a rotary forging mill for multi-pass continuous rotary forging, with a diameter reduction of 1-2 mm per pass, and the initial billet having a diameter of approximately 10-10 mm. 2 s ‑1 The high strain rate and deformation under high hydrostatic stress generated by mold impact ultimately yield aluminum-clad magnesium composite rods. Advantages of this invention: This invention utilizes cold-working rotary forging technology to achieve dissimilar metal composites, making magnesium alloys, which are difficult to form at room temperature, easier to form under the cladding of aluminum alloys. This results in aluminum-clad magnesium composite rods with a mechanically interlocked composite interface and accompanying metallurgical bonding, significantly reducing processing difficulty and cost.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation technology, and in particular to a method for preparing aluminum-clad magnesium composite rods. Background Technology

[0002] Magnesium alloys are currently the lightest metallic structural materials, possessing advantages such as low density, high specific strength and specific stiffness, good damping and vibration reduction properties, and excellent electromagnetic shielding. They have been used for many years in industries such as aerospace, automotive, and electronics and communications. However, magnesium alloys have a low-symmetry, close-packed hexagonal crystal structure with a low coefficient of slip at room temperature, resulting in lower plasticity, poor metal flowability, and difficulty in processing. Aluminum alloys are also lightweight materials with good plasticity, moderate strength, and excellent corrosion resistance. Aluminum-clad magnesium composite rods not only improve the plastic deformation capacity of magnesium alloys but also enhance the corrosion resistance of the magnesium alloy surface and improve its ductility. This is because composite materials combine the properties of different materials to cover their weaknesses and improve the overall efficiency of multilayer components.

[0003] Generally, the preparation of composite materials requires heating the materials, or even melting the coating material onto the core material surface and then cooling and solidifying it to form a coating. For example, different materials may be heated and extruded. This method is time-consuming, labor-intensive, and costly. Furthermore, it can cause the formation of coarse oxides on the material surface and at the composite interface, severely damaging the mechanical properties of the materials and even having a negative impact on the mechanical properties of the composite material. Therefore, to address the problems in existing technologies, we have developed a method for preparing aluminum-clad magnesium composite rods. Summary of the Invention

[0004] To address the problems of time-consuming, labor-intensive, and costly preparation methods for aluminum-clad magnesium composite rods, which also result in coarse oxides on the surface and interface of the composite material, this invention provides a method for manufacturing aluminum-clad magnesium composite rods with uniform composite interface width at room temperature using rotary forging, which significantly reduces processing difficulty and cost.

[0005] This invention provides a method for preparing aluminum-clad magnesium composite rods, the specific operation steps of which are as follows: S1: Grind and clean the surface of the magnesium alloy mandrel before use; S2: Grind and clean the inner wall and surface of the aluminum alloy tube for later use; S3: Assembly of magnesium alloy core rod and aluminum alloy tube: Place the cleaned magnesium alloy core rod obtained in step S1 into the cleaned aluminum alloy tube obtained in step S2. The magnesium alloy core rod and the aluminum alloy tube are in clearance fit, with a small gap of 0.1 to 0.2 mm between them. S4: Initial blank for rotary forging of aluminum-clad magnesium: The initial blank assembled in step S3 is fed into a rotary forging mill for multi-pass continuous rotary forging. The diameter reduction in each pass is 1-2 mm, and the initial blank is approximately 10-10 mm in diameter. 2 s -1 The high strain rate and deformation under high hydrostatic stress generated by mold impact ultimately yield aluminum-clad magnesium composite rods.

[0006] In some embodiments, the cleaning method in step S1 specifically involves: wiping the surface of the magnesium alloy core rod with anhydrous ethanol to remove surface oil and oxides, then lightly polishing the surface of the core rod with 400-grit, 800-grit, 1200-grit, and 2000-grit sandpaper respectively to increase the composite effect of the magnesium alloy core rod and the aluminum alloy tube, then wiping the magnesium alloy core rod with anhydrous ethanol again, and then drying it.

[0007] In some embodiments, the cleaning method in step S2 specifically involves: wiping the inner wall of the aluminum alloy pipe with a cotton swab soaked in anhydrous ethanol to remove oil and oxides; then lightly polishing it with a pipe wire brush of the same size as the inner diameter of the aluminum alloy pipe to increase the composite effect of the magnesium alloy core rod and the aluminum alloy pipe; then wiping the inner wall of the aluminum alloy pipe with anhydrous ethanol and drying it; and finally wiping the outer wall of the aluminum alloy pipe with anhydrous ethanol to remove surface oil.

[0008] In some embodiments, the rotary forging process parameters in step S4 include the diameter ratio of the magnesium alloy and aluminum alloy materials, the number of rotary forging passes, the strain rate, the feed rate, the die structure, and the final dimensions of the aluminum-clad magnesium composite bar.

[0009] The present invention also provides an aluminum-clad magnesium composite rod prepared by the method described in any one of the above-mentioned methods, comprising a magnesium alloy core rod and an aluminum alloy tube, wherein the magnesium alloy core rod is inserted into the aluminum alloy tube, and the diameter of the magnesium alloy core rod and the inner diameter of the aluminum alloy tube are clearance-fitted.

[0010] Compared with the prior art, the above-mentioned technical solution of the present invention has the following advantages: The present invention utilizes cold working rotary forging technology to achieve dissimilar metal composite, making magnesium alloys, which are difficult to form at room temperature, easier to form under the cladding of aluminum alloys, and obtaining aluminum-clad magnesium composite rods with uniform composite interface width, which greatly reduces the processing difficulty and cost. The entire composite process is a physical bonding mechanism, with low energy consumption and environmental protection. Attached Figure Description

[0011] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0012] Figure 1A schematic diagram of the machining structure for rotary forged aluminum-clad magnesium composite bars; Figure 2 The images show the SEM images and EDS composition analysis results of the composite interface of the aluminum-clad magnesium composite rod of the present invention. Figure 3 This is the result of the shear force test of the material of this invention.

[0013] Explanation of reference numerals in the attached drawings: 1. Magnesium alloy mandrel; 2. Aluminum alloy tube; 10. Magnesium-aluminum composite rod initial billet; 3. Mold. Detailed Implementation

[0014] The technical solution of the present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way. Example 1

[0015] Prepare a 10mm diameter magnesium alloy core rod 1 and a 10mm inner diameter aluminum alloy tube 2, ensuring a clearance fit between the core rod 1 and tube 2. Wipe the surface of the magnesium alloy core rod 1 with anhydrous ethanol to remove oil and oxides. Then, successively polish the surface of the core rod 1 with 400, 800, 1200, and 2000 grit sandpaper until the diameter is approximately 9.8mm. Wipe the core rod 1 again with anhydrous ethanol and then dry it. Wipe the inner wall of the aluminum alloy tube 2 with a cotton swab soaked in anhydrous ethanol to remove oil and oxides. Then, lightly polish the inner wall with a wire brush matching the inner diameter of the tube to enhance the composite effect of the magnesium alloy core rod 1 and tube 2. Finally, wipe the inner wall of the tube with anhydrous ethanol and then dry it.

[0016] like Figure 1 As shown, a magnesium alloy mandrel 1 is inserted into an aluminum alloy tube 2 to form an initial magnesium-aluminum composite billet 10, with a small gap of 0.1-0.2 mm between the magnesium alloy mandrel 1 and the aluminum alloy tube 2. The initial magnesium-aluminum composite billet 10 is then loaded into the mold 3 of a rotary forging machine. Preferably, in this embodiment, an X20 rotary forging machine is used, with a rotation speed of 120 r / min, a pressure of 10 t, and a forging time of 2 min per pass. The rotary forging machine is started to begin rotary forging the initial magnesium-aluminum composite billet 10. The initial magnesium-aluminum composite billet 10 is approximately 10-10 mm thick. 2 s -1 Under high strain rate and high hydrostatic stress generated by die impact, the diameter is reduced by 1-2 mm per pass. Multiple passes of continuous rotary forging are performed until an aluminum-clad magnesium composite bar with a diameter of 8 mm is obtained. The forged magnesium-aluminum composite bar is taken out from the rotary forging press and its surface quality and bonding interface are checked.

[0017] In this embodiment, the composite layer of magnesium alloy mandrel 1 and aluminum alloy tube 2 is formed under solid deformation conditions of rotary forging with high temperature and high pressure. During the rotary forging process, the interface between magnesium alloy mandrel 1 and aluminum alloy tube 2 is fully contacted and diffuses into each other at the atomic scale to form an interface layer, thereby achieving the effect of metallurgical bonding and improving the comprehensive performance of the material.

[0018] Figure 2 The figures show a cross-sectional view of the aluminum-clad magnesium composite rod, SEM images of the composite material, and EDS composition analysis results, including surface and line scans. As can be seen from the figures, the interface between the magnesium alloy core rod 1 and the aluminum alloy tube 2 has a relatively obvious diffusion layer. The composite interface width is uniform, without defects such as pores or burrs, indicating a good solid-state composite effect. Furthermore, the EDS composition analysis results show that the mass percentage of magnesium and aluminum elements at the magnesium-aluminum composite interface exhibits an "X" shape relationship with the diffusion distance, and the elemental changes are gradual, indicating that the diffusion thickness of magnesium elements from the aluminum element side is relatively uniform. In this embodiment, the diffusion thickness of magnesium elements from the aluminum element side is approximately 3 μm, achieving effective solid-state welding.

[0019] Figure 3 Magnesium-aluminum composite sheets were obtained by wire cutting along the axial direction of the magnesium-aluminum composite rod. A shear strength test was conducted on the magnesium-aluminum composite material, and the shear strength was measured to be 53.6 MPa. This indicates that the magnesium-aluminum composite rod interface has good mechanical bonding strength. The aluminum-clad magnesium composite rod obtained in this embodiment combines the advantages of both aluminum and magnesium, exhibiting excellent plastic deformation capacity, high surface corrosion resistance, and good ductility. It can be used as an advanced material in aerospace, automotive, and electronic communications fields.

[0020] In other embodiments, when assembling the magnesium alloy mandrel 1 and the aluminum alloy tube 2, aluminum-clad magnesium composite rods of different diameters can be obtained by changing the diameter ratio of the outer diameter of the magnesium alloy mandrel 1 and the aluminum alloy tube 2, or by changing the number of passes in the rotary forging process, and the strength and thickness of the composite interface between the magnesium alloy and the aluminum alloy can be controlled.

[0021] Working Principle: This invention enables continuous production by feeding materials at room temperature. It utilizes cold forging technology to achieve dissimilar metal composites, making magnesium alloys, which are difficult to form at room temperature, easier to form when encased in aluminum alloy, thus improving the metal flowability of the magnesium alloy during processing. First, a magnesium alloy mandrel is placed inside an aluminum alloy tube. Then, the original billet is fed into the forging machine. During the forging process, the mandrel is rotated approximately 10-10 mm. 2 s -1Under high strain rates and high hydrostatic stress from die impact, aluminum alloy tubing is uniformly coated onto a magnesium alloy mandrel during rotary forging heating and high pressure, achieving magnesium-aluminum alloy composite. The strength and thickness of the magnesium-aluminum alloy composite interface are controlled, while a dense oxide layer is formed on the aluminum alloy surface. Product quality is stable, and the entire composite process utilizes a physical bonding mechanism, resulting in low energy consumption and environmental friendliness.

[0022] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, 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. A method for preparing an aluminum-clad magnesium composite rod, characterized in that, Includes the following steps: S1: Grind and clean the surface of the magnesium alloy mandrel before use; S2: Grind and clean the inner wall and surface of the aluminum alloy tube for later use; S3: Assembly of magnesium alloy core rod and aluminum alloy tube: Place the cleaned magnesium alloy core rod obtained in step S1 into the cleaned aluminum alloy tube obtained in step S2. The magnesium alloy core rod and the aluminum alloy tube are in clearance fit, with a small gap of 0.1 to 0.2 mm between them. S4: Initial blank for rotary forging of aluminum-clad magnesium: The initial blank assembled in step S3 is fed into a rotary forging mill for multi-pass continuous rotary forging. The diameter reduction in each pass is 1-2 mm, and the initial blank is approximately 10-10 mm in diameter. 2 s -1 The high strain rate and deformation under high hydrostatic stress generated by mold impact ultimately yield aluminum-clad magnesium composite rods.

2. The method for preparing an aluminum-clad magnesium composite rod according to claim 1, characterized in that, The cleaning method described in step S1 is as follows: wipe the surface of the magnesium alloy core rod with anhydrous ethanol to remove surface oil and oxides, then lightly polish the surface of the core rod with sandpaper of 400 grit, 800 grit, 1200 grit and 2000 grit respectively to increase the composite effect of the magnesium alloy core rod and the aluminum alloy tube, then wipe the magnesium alloy core rod with anhydrous ethanol again, and then dry it.

3. The method for preparing an aluminum-clad magnesium composite rod according to claim 1, characterized in that, The cleaning method described in step S2 is as follows: Wipe the inner wall of the aluminum alloy pipe with a cotton swab soaked in anhydrous ethanol to remove oil and oxides. Then, use a pipe wire brush of the same size as the inner diameter of the aluminum alloy pipe to lightly polish it to increase the composite effect of the magnesium alloy core rod and the aluminum alloy pipe. Then, wipe the inner wall of the aluminum alloy pipe with anhydrous ethanol and dry it. Finally, wipe the outer wall of the aluminum alloy pipe with anhydrous ethanol to remove oil from its surface.

4. The method for preparing an aluminum-clad magnesium composite rod according to claim 1, characterized in that, The rotary forging process parameters in step S4 include the diameter ratio of magnesium alloy and aluminum alloy materials, the number of rotary forging passes, strain rate, feed rate, die structure, and the final dimensions of the aluminum-clad magnesium composite bar.

5. The aluminum-clad magnesium composite rod prepared by the method according to any one of claims 1 to 4, characterized in that, It includes a magnesium alloy core rod and an aluminum alloy tube, wherein the magnesium alloy core rod is inserted into the aluminum alloy tube, and the diameter of the magnesium alloy core rod and the inner diameter of the aluminum alloy tube are in clearance fit.

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