High-toughness magnesium alloy wire material based on electric pulse annealing treatment and preparation method of high-toughness magnesium alloy wire material

Abstract

The invention discloses a high-toughness magnesium alloy wire based on electric pulse annealing treatment and a preparation method of the high-toughness magnesium alloy wire, and belongs to the technical field of preparation of high-performance metal materials. The preparation method comprises the following steps: (1) selecting a commercial magnesium alloy wire with the diameter of 2mm as a raw material; (2) the raw materials obtained in the step (1) are subjected to homogenizing annealing treatment, and then the surface of the wire is polished; (3) the material obtained in the step (2) is subjected to three-pass continuous cold drawing machining; (4) the cold-drawn wire obtained in the step (3) is subjected to electric pulse annealing treatment; and (5) repeating the steps (3)-(4) for 1-3 times until the wire with the diameter of 1.00-1.43 mm is obtained. The machining method of multi-pass cold drawing and electric pulse annealing is adopted, rapid recrystallization and structure homogenization of the material can be achieved within tens of seconds, the magnesium alloy wire with the average grain size being 2-4 microns is obtained, the excellent mechanical property is shown at the room temperature, and the magnesium alloy wire can be used for manufacturing the high-strength magnesium alloy wire. The method has the advantages of high annealing efficiency, short process flow, obvious improvement of mechanical properties and the like.

Description

Technical Field

[0001] This invention relates to a high-strength and high-toughness magnesium alloy wire based on electric pulse annealing and its preparation method, belonging to the field of high-performance metal material preparation technology. Background Technology

[0002] Magnesium and its alloys, due to their advantages such as low density, high specific strength, excellent electromagnetic shielding performance, and high recyclability, are widely used in aerospace, automotive, electronic devices, and biomedical fields, making them one of the most promising lightweight structural metal materials. Among them, magnesium alloy filaments have broad application prospects in precision parts, connecting components, and medical sutures. However, limited by the close-packed hexagonal crystal structure of magnesium alloys, the number of movable slip systems at room temperature is relatively small, resulting in limited plastic deformation capacity and making them prone to work hardening and cracking during processing. In the preparation of filaments with a diameter less than 2 mm, a multi-pass cold drawing combined with intermediate annealing is typically required for gradual deformation. As the filament diameter gradually decreases, the material's deformation resistance increases significantly, easily leading to intensified work hardening and increased wire breakage rate, severely restricting yield and production efficiency, and making it difficult to achieve an efficient and stable continuous filament production process.

[0003] Currently, the commonly used intermediate annealing process is traditional heat treatment, such as furnace annealing, resistance heating annealing, and medium-high frequency induction heating annealing. This involves holding the material at a certain temperature for several tens of minutes to achieve recrystallization and softening of the microstructure. Chinese patent CN117230354A discloses a high-strength and tough rare-earth magnesium alloy wire for additive manufacturing and its preparation method. This method can only extrude magnesium alloy into wire blanks with a diameter of 8.0 to 10.0 mm, and then perform continuous multi-pass hot drawing processing on the blanks to obtain magnesium alloy wires with a diameter of 1.2 to 6.0 mm. It also requires multiple intermediate annealing treatments, resulting in a long process flow, low production efficiency, and high cost. Chinese patent CN118950733A discloses a method for preparing rare earth magnesium alloy wire for arc additive manufacturing. This method involves multiple hot drawing processes to obtain magnesium alloy wire with a diameter of 1.35–1.45 mm. However, the wire length produced in a single pass is limited, and intermediate processes such as resistance welding and peeling are required. The process is lengthy, requires numerous pieces of equipment, and the highest tensile strength of the resulting wire is only 273 MPa, with an elongation of less than 10%, indicating poor performance. Chinese patent CN120555850A discloses a biomedical high-plasticity, ultra-wear-resistant magnesium alloy wire and its preparation method. This method utilizes cold drawing and intermediate annealing to obtain magnesium alloy wire with a diameter of 0.3–1.0 mm. However, the tensile strength of the wire is less than 300 MPa, the elongation is less than 13%, and frequent, long-term, high-temperature intermediate annealing treatments are required, which cannot meet the actual needs of high-performance medical materials.

[0004] While the aforementioned methods can improve plasticity, they generally suffer from high energy consumption, long processing times, and low efficiency, making it difficult to meet the demands of efficient continuous wire-making processes. Furthermore, in traditional annealing processes, heat is primarily introduced through external conduction, resulting in a slow temperature rise rate and uneven local temperature distribution within the material, easily leading to inhomogeneous microstructure and low mechanical properties. Therefore, overcoming the shortcomings of traditional magnesium alloy wire production processes and developing an efficient, low-cost method capable of stably producing magnesium alloy fine wires with excellent properties is of great significance. Summary of the Invention

[0005] To address the problems of insufficient plasticity, low efficiency of traditional intermediate annealing, coarse microstructure, and uneven properties in the cold working of magnesium alloy wires, this invention aims to provide a high-strength and high-toughness magnesium alloy wire based on electro-pulse annealing and its preparation method. Unlike existing processes that typically perform a unified electro-pulse treatment after multiple processing passes, this invention embeds electro-pulse annealing into a multi-pass cold drawing process, replacing traditional heat treatment with electro-pulse annealing to achieve integrated and online control of the process. By optimizing pulse parameters, the material can achieve sufficient recrystallization and microstructure homogenization within 60 seconds, while traditional heat treatment usually requires a longer time and higher temperature, resulting in high energy consumption, low efficiency, and a tendency to induce abnormal grain growth and performance fluctuations. When the pulsed current passes through the metal, drifting electrons exert a directional thrust on dislocations, promoting dislocation untangling and rearrangement, and forming dislocation cells and subgrain structures locally, becoming potential nucleation sites for recrystallization. Simultaneously, the electron wind can drive grain boundary migration, accelerating the growth of recrystallization nuclei, enabling the material to quickly complete recrystallization. Based on the above mechanism, electropulse annealing not only significantly improves the strength-plasticity synergy of filaments, but also reduces energy consumption and improves filament production efficiency. It has advantages such as high process repeatability, short processing time and excellent comprehensive performance.

[0006] This invention provides a method for preparing high-strength and high-toughness magnesium alloy wire based on electrical pulse annealing, comprising the following steps: (1) Select magnesium alloy wire with a diameter of 2 mm as raw material; (2) The raw material obtained in step (1) is subjected to homogenization annealing treatment, and then the surface of the wire is polished. (3) The material obtained in step (2) is subjected to three consecutive cold drawing processes; (4) Perform electrical pulse annealing on the cold-drawn wire obtained in step (3); (5) Repeat steps (3) to (4) 1 to 3 times until a wire with a diameter of 1.00 to 1.43 mm is obtained.

[0007] The above preparation method specifically includes the following steps: (1) Raw material preparation Commercial magnesium alloy wire with a diameter of 2 mm was selected as the raw material. The commercial magnesium alloy wire is AZ31 alloy with the composition of Al 2.5–3.5 wt.%, Zn 0.6–1.2 wt.%, Mn 0.2–0.4 wt.%, and the balance being Mg.

[0008] (2) Homogenization annealing Magnesium alloy wire is placed in a muffle furnace for homogenization annealing. The power supply to the muffle furnace is turned on, and the temperature is raised to 300-350℃ and held for 2-2.5 hours. The power supply to the muffle furnace is turned off, and the magnesium alloy wire is taken out and cooled to room temperature in the air. (3) Three-pass cold drawing After homogenization and annealing, the surface of the wire was polished with 400-grit sandpaper to make it smooth. The polished magnesium alloy wire was placed in a steel drawing die. Before each cold drawing pass, the wire and the die were lubricated with a lubricant. The drawing machine was started, and three cold drawing processes were carried out at room temperature. The drawing speed was 2-4 m / min, the deformation per pass was 10%, and the cumulative deformation was 30%. (4) Intermediate annealing Magnesium alloy wires obtained by three cold drawing processes were placed between the two electrodes of a bidirectional pulse power supply for electro-pulse annealing. Both ends of the wires were connected to electric clamps, one of which was connected to the positive pulse current output electrode of the pulse power supply, and the other was connected to the negative pulse current output electrode of the pulse power supply. The pulse voltage of the electro-pulse annealing process was 60–120 V, the pulse frequency was 100–200 Hz, the pulse width was 35–45 μs, and the processing time was 40–60 s. After annealing, the wires were cooled to room temperature in air. (5) Repeated processing Repeat steps (3) to (4) 1 to 3 times until a wire with a diameter of 1.00 to 1.43 mm is obtained.

[0009] The magnesium alloy wire prepared by the method of this invention has an average grain size of 2–4 μm, and its room temperature mechanical properties meet the following requirements: tensile strength ≥ 310 MPa, elongation after fracture ≥ 25%, and Vickers microhardness ≥ 85 HV. 1.0 .

[0010] The beneficial effects of this invention are: (1) Simple process and low cost: The high-strength and tough magnesium alloy wire and its preparation method based on electric pulse annealing provided by the present invention adopts a processing route combining "multi-pass cold drawing + electric pulse annealing" to realize the whole process of cold forming of magnesium alloy wire. This process greatly shortens the processing cycle of magnesium alloy wire, improves production efficiency and reduces production cost while ensuring the surface quality and performance stability of the wire. (2) Significant grain refinement: This invention uses electric pulse annealing instead of traditional furnace annealing, which can effectively promote the static recrystallization of deformed magnesium alloy wire and achieve significant grain refinement. Testing showed that the average grain size of the prepared magnesium alloy wire was 2–4 μm. Compared with magnesium alloy wire prepared by traditional heat treatment processes, the grain size was significantly reduced and the microstructure was more uniform. (3) Excellent performance: The high-density electron wind and transient electrical stress generated during the electric pulse annealing process can effectively promote dislocation slip and climb, reduce dislocation entanglement density, and enhance grain boundary migration ability, thereby accelerating recrystallization and texture optimization. Tests showed that the prepared magnesium alloy wire has excellent comprehensive mechanical properties: tensile strength of 310–360 MPa, elongation after fracture of 25%–33%, and microhardness of 85–103 HV, exhibiting excellent strength-plasticity synergy and good fatigue resistance. (4) Wide range of applications: The process of this invention has a wide range of applications. It can be used not only for intermediate annealing of AZ31 magnesium alloy wire, but also for various magnesium alloys such as AZ91, ZK60, and WE43, as well as their rods, strips, and other products. This method has good adaptability to magnesium alloy wires with different chemical compositions, different diameters, and different degrees of deformation. According to the changes in wire diameter, the energy input can be precisely matched by adjusting the pulse voltage, pulse frequency, pulse width, and processing time, which has broad application prospects. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the preparation process of the present invention; Figure 2 The image shows the metallographic microstructure of the magnesium alloy wire after cold drawing in step 5) of Example 2. Figure 3 The image shows the metallographic microstructure of the magnesium alloy wire after electrical pulse annealing in step 5) of Example 2. Figure 4 The X-ray diffraction (XRD) patterns of the magnesium alloy wire before and after the electric pulse annealing treatment obtained in Example 2 are shown below. Figure 5 This is the (0001) pole figure of the magnesium alloy wire after cold drawing in step 5) of Example 2; Figure 6 This is the (0001) pole figure of the magnesium alloy wire after electrical pulse annealing in step 5) of Example 2; Figure 7 This is a schematic diagram of the engineering stress-strain curves of magnesium alloy wire under different treatment conditions. Detailed Implementation

[0012] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0013] This invention provides a high-strength and high-toughness magnesium alloy wire based on electrical pulse annealing and its preparation method, comprising the following steps: (1) Commercial magnesium alloy wire with a diameter of 2 mm was selected as raw material. The commercial magnesium alloy wire was AZ31 alloy with the composition of Al 2.5–3.5 wt.%, Zn 0.6–1.2 wt.%, Mn 0.2–0.4 wt.%, and the balance being Mg; (2) Place the magnesium alloy wire obtained in step (1) in a muffle furnace for homogenization annealing, turn on the power of the muffle furnace, heat to 300-350 ℃, and hold for 2-2.5 h; turn off the power of the muffle furnace, take out the magnesium alloy wire, and cool it to room temperature in the air. (3) The homogenized annealed wire obtained in step (2) is polished with 400-grit sandpaper to make it smooth. The polished magnesium alloy wire is placed in a steel drawing die. Before each cold drawing, the wire and the die are lubricated with lubricant. The drawing machine is started and the three cold drawing processes are carried out at room temperature. The drawing speed is 2-4 m / min, the deformation per pass is 10%, and the cumulative deformation is 30%.

[0014] (4) The cold-drawn magnesium alloy wire obtained in step (3) is placed between the two poles of the bidirectional pulse power supply for electric pulse annealing. The two ends of the wire are connected to the electric clamps respectively. One electric clamp is connected to the positive pulse current output electrode of the pulse power supply, and the other electric clamp is connected to the negative pulse current output electrode of the pulse power supply. The pulse voltage of the electric pulse annealing is 60-120 V, the pulse frequency is 100-200 Hz, the pulse width is 35-45 μs, and the processing time is 40-60 s. After annealing, the wire is cooled to room temperature in the air. (5) Repeat steps (3) and (4) 1 to 3 times until a wire with a diameter of 1.00 to 1.43 mm is obtained.

[0015] The following detailed experimental process further illustrates the effectiveness of this invention. Example 1

[0016] A high-strength and high-toughness magnesium alloy wire based on electrical pulse annealing and its preparation method, comprising the following steps: 1) Commercial magnesium alloy wire with a diameter of 2 mm was selected as the raw material. The commercial magnesium alloy wire was AZ31 alloy with a composition of 3.1 wt.% Al, 0.9 wt.% Zn, 0.4 wt.% Mn, and the balance being Mg. 2) Place the magnesium alloy wire obtained in step 1) into a muffle furnace for homogenization annealing, turn on the power of the muffle furnace, heat to 350 ℃, and hold for 2 h; turn off the power of the muffle furnace, take out the magnesium alloy wire, and cool it to room temperature in the air. 3) The homogenized annealed wire obtained in step 2) is polished with 400-grit sandpaper to make it smooth. The polished magnesium alloy wire is placed in a steel drawing die. Before each cold drawing, the wire and the die are lubricated with lubricant. The drawing machine is started and three cold drawing processes are carried out at room temperature. The drawing speed is 2 m / min, the deformation per pass is 10%, and the cumulative deformation is 30%.

[0017] 4) The cold-drawn magnesium alloy wire obtained in step 3) is placed between the two poles of a bidirectional pulse power supply for electro-pulse annealing. Both ends of the wire are connected to electric clamps. One electric clamp is connected to the positive pulse current output electrode of the pulse power supply, and the other electric clamp is connected to the negative pulse current output electrode of the pulse power supply. The pulse voltage of the electro-pulse annealing treatment is 60 V, the pulse frequency is 200 Hz, the pulse width is 45 μs, and the treatment time is 60 s. After annealing, the wire is cooled to room temperature in air. 5) Repeat steps 3) and 4) once to obtain a wire with a diameter of 1.43 mm.

[0018] 6) Characterization of microstructure and mechanical properties. The magnesium alloy wire obtained by this method can achieve complete recrystallization within 60 s, with significant grain refinement and an average grain size of 2.9 μm; the tensile strength is 353 MPa, the elongation after fracture is 25%, and the hardness is 101 HV. 1.0 . Example 2

[0019] A high-strength and high-toughness magnesium alloy wire based on electrical pulse annealing and its preparation method, comprising the following steps: 1) Commercial magnesium alloy wire with a diameter of 2 mm was selected as the raw material. The commercial magnesium alloy wire was AZ31 alloy with a composition of 3.1 wt.% Al, 0.9 wt.% Zn, 0.4 wt.% Mn, and the balance being Mg. 2) Place the magnesium alloy wire obtained in step 1) into a muffle furnace for homogenization annealing, turn on the power of the muffle furnace, heat to 325 ℃, and hold for 2.2 h; turn off the power of the muffle furnace, take out the magnesium alloy wire, and cool it to room temperature in the air. 3) The homogenized annealed wire obtained in step 2) is polished with 400-grit sandpaper to make it smooth. The polished magnesium alloy wire is placed in a steel drawing die. Before each cold drawing, the wire and the die are lubricated with lubricant. The drawing machine is started and three cold drawing processes are carried out at room temperature. The drawing speed is 3 m / min, the deformation per pass is 10%, and the cumulative deformation is 30%.

[0020] 4) The cold-drawn magnesium alloy wire obtained in step 3) is placed between the two poles of a bidirectional pulse power supply for electro-pulse annealing. Both ends of the wire are connected to electric clamps. One electric clamp is connected to the positive pulse current output electrode of the pulse power supply, and the other electric clamp is connected to the negative pulse current output electrode of the pulse power supply. The pulse voltage of the electro-pulse annealing treatment is 90 V, the pulse frequency is 150 Hz, the pulse width is 40 μs, and the treatment time is 50 s. After annealing, the wire is cooled to room temperature in air. 5) Repeat steps 3) and 4) once to obtain a wire with a diameter of 1.43 mm.

[0021] 6) Characterization of microstructure and mechanical properties. The magnesium alloy wire obtained by this method can achieve complete recrystallization within 50 seconds, with significantly refined grains, an average grain size of 3.4 μm, a tensile strength of 321 MPa, an elongation of 28%, and a hardness of 92 HV. 1.0 . Example 3

[0022] A high-strength and high-toughness magnesium alloy wire based on electrical pulse annealing and its preparation method, comprising the following steps: 1) Commercial magnesium alloy wire with a diameter of 2 mm was selected as the raw material. The commercial magnesium alloy wire was AZ31 alloy with a composition of 3.1 wt.% Al, 0.9 wt.% Zn, 0.4 wt.% Mn, and the balance being Mg; 2) Place the magnesium alloy wire obtained in step 1) into a muffle furnace for homogenization annealing, turn on the power of the muffle furnace, heat to 350 ℃, and hold for 2 h; turn off the power of the muffle furnace, take out the magnesium alloy wire, and cool it to room temperature in the air. 3) The homogenized annealed wire obtained in step 2) is polished with 400-grit sandpaper to make it smooth. The polished magnesium alloy wire is placed in a steel drawing die. Before each cold drawing, the wire and the die are lubricated with lubricant. The drawing machine is started and three cold drawing processes are carried out at room temperature. The drawing speed is 4 m / min, the deformation per pass is 10%, and the cumulative deformation is 30%.

[0023] 4) The cold-drawn magnesium alloy wire obtained in step 3) is placed between the two poles of a bidirectional pulse power supply for electro-pulse annealing. Both ends of the wire are connected to electric clamps. One electric clamp is connected to the positive pulse current output electrode of the pulse power supply, and the other electric clamp is connected to the negative pulse current output electrode of the pulse power supply. The pulse voltage of the electro-pulse annealing is 120 V, the pulse frequency is 150 Hz, the pulse width is 35 μs, and the processing time is 40 s. After annealing, the wire is cooled to room temperature in air. 5) Repeat steps 3) and 4) once to obtain a wire with a diameter of 1.43 mm.

[0024] 6) Characterization of microstructure and mechanical properties. The magnesium alloy wire obtained by this method can achieve complete recrystallization within 40 seconds, with significantly refined grains, an average grain size of 4.0 μm, a tensile strength of 318 MPa, an elongation of 33%, and a hardness of 88 HV. 1.0 . Example 4

[0025] A high-strength and high-toughness magnesium alloy wire based on electrical pulse annealing and its preparation method, comprising the following steps: 1) Commercial magnesium alloy wire with a diameter of 2 mm was selected as the raw material. The commercial magnesium alloy wire was AZ31 alloy with a composition of 3.1 wt.% Al, 0.9 wt.% Zn, 0.4 wt.% Mn, and the balance being Mg. 2) Place the magnesium alloy wire obtained in step 1) into a muffle furnace for homogenization annealing, turn on the power of the muffle furnace, heat to 300 ℃, and hold for 2.5 h; turn off the power of the muffle furnace, take out the magnesium alloy wire, and cool it to room temperature in the air. 3) The homogenized annealed wire obtained in step 2) is polished with 400-grit sandpaper to make it smooth. The polished magnesium alloy wire is placed in a steel drawing die. Before each cold drawing, the wire and the die are lubricated with lubricant. The drawing machine is started and three cold drawing processes are carried out at room temperature. The drawing speed is 3 m / min, the deformation per pass is 10%, and the cumulative deformation is 30%.

[0026] 4) The cold-drawn magnesium alloy wire obtained in step 3) is placed between the two poles of a bidirectional pulse power supply for electro-pulse annealing. Both ends of the wire are connected to electric clamps. One electric clamp is connected to the positive pulse current output electrode of the pulse power supply, and the other electric clamp is connected to the negative pulse current output electrode of the pulse power supply. The pulse voltage of the electro-pulse annealing treatment is 90 V, the pulse frequency is 150 Hz, the pulse width is 40 μs, and the treatment time is 50 s. After annealing, the wire is cooled to room temperature in air. 5) Repeat steps 3) and 4) twice to obtain a wire with a diameter of 1.20 mm.

[0027] 6) Characterization of microstructure and mechanical properties. The magnesium alloy wire obtained by this method can achieve complete recrystallization within 50 seconds, with significantly refined grains, an average grain size of 3.2 μm, a tensile strength of 312 MPa, an elongation of 30%, and a hardness of 90 HV. 1.0 . Example 5

[0028] A high-strength and high-toughness magnesium alloy wire based on electrical pulse annealing and its preparation method, comprising the following steps: 1) Commercial magnesium alloy wire with a diameter of 2 mm was selected as the raw material. The commercial magnesium alloy wire was AZ31 alloy with a composition of 3.1 wt.% Al, 0.9 wt.% Zn, 0.4 wt.% Mn, and the balance being Mg. 2) Place the magnesium alloy wire obtained in step 1) into a muffle furnace for homogenization annealing, turn on the power of the muffle furnace, heat to 300 ℃, and hold for 2.5 h; turn off the power of the muffle furnace, take out the magnesium alloy wire, and cool it to room temperature in the air. 3) The homogenized annealed wire obtained in step 2) is polished with 400-grit sandpaper to make it smooth. The polished magnesium alloy wire is placed in a steel drawing die. Before each cold drawing, the wire and the die are lubricated with lubricant. The drawing machine is started and three cold drawing processes are carried out at room temperature. The drawing speed is 2 m / min, the deformation per pass is 10%, and the cumulative deformation is 30%.

[0029] 4) The cold-drawn magnesium alloy wire obtained in step 3) is placed between the two poles of a bidirectional pulse power supply for electro-pulse annealing. Both ends of the wire are connected to electric clamps. One electric clamp is connected to the positive pulse current output electrode of the pulse power supply, and the other electric clamp is connected to the negative pulse current output electrode of the pulse power supply. The pulse voltage of the electro-pulse annealing is 120 V, the pulse frequency is 100 Hz, the pulse width is 40 μs, and the processing time is 40 s. After annealing, the wire is cooled to room temperature in air. 5) Repeat steps 3) and 4) twice to obtain a wire with a diameter of 1.20 mm.

[0030] 6) Characterization of microstructure and mechanical properties. The magnesium alloy wire obtained by this method can achieve complete recrystallization within 40 seconds, with significantly refined grains, an average grain size of 3.5 μm, a tensile strength of 310 MPa, an elongation of 32%, and a hardness of 85 HV. 1.0 . Comparative Example 1

[0031] A method for preparing magnesium alloy wire based on conventional heat treatment furnace annealing includes the following steps: 1) Commercial magnesium alloy wire with a diameter of 2 mm was selected as the raw material. The commercial magnesium alloy wire was AZ31 alloy with a composition of 3.1 wt.% Al, 0.9 wt.% Zn, 0.4 wt.% Mn, and the balance being Mg. 2) Place the magnesium alloy wire obtained in step 1) into a muffle furnace for homogenization annealing, turn on the power of the muffle furnace, heat to 300 ℃, and hold for 2.5 h; turn off the power of the muffle furnace, take out the magnesium alloy wire, and cool it to room temperature in the air. 3) The homogenized annealed wire obtained in step 2) is polished with 400-grit sandpaper to make it smooth. The polished magnesium alloy wire is placed in a steel drawing die. Before each cold drawing, the wire and the die are lubricated with lubricant. The drawing machine is started and three cold drawing processes are carried out at room temperature. The drawing speed is 3 m / min, the deformation per pass is 10%, and the cumulative deformation is 30%.

[0032] 4) The cold-drawn magnesium alloy wire obtained in step 3) is placed in a muffle furnace for conventional annealing treatment. The annealing temperature is 250 ℃ and the annealing time is 10 min. After annealing, the wire is cooled to room temperature in air. 5) Repeat steps 3) and 4) once to obtain a wire with a diameter of 1.43 mm.

[0033] 6) Characterization of microstructure and mechanical properties. The magnesium alloy wire obtained by this method requires 10 minutes to achieve complete recrystallization, with an average grain size of 5.4 μm, a tensile strength of 295 MPa, an elongation of 22.5%, and a hardness of 78 HV. 1.0 .

[0034] This invention detects, analyzes, and characterizes the metallographic structure, mechanical properties, and texture of the prepared high-strength and high-toughness magnesium alloy wire; Figure 2 The image shows the metallographic microstructure of the magnesium alloy wire after cold drawing in step 5 of Example 2. It can be seen that after multiple cold drawing passes, a large number of twins are formed inside the material, and the grains are significantly elongated along the drawing direction, exhibiting a typical fibrous structure. At the same time, the deformation bands are densely distributed, and the grain boundaries are significantly cut, indicating that the material is in a highly work-hardened state. Figure 3 The image shows the metallographic microstructure of the magnesium alloy wire after electro-pulse annealing in step 5 of Example 2. It can be seen that the original fibrous deformation structure has basically disappeared and has been replaced by uniformly distributed equiaxed recrystallized grains. The twins have been completely eliminated and the average grain size is about 3.4 μm. This indicates that electro-pulse annealing can effectively induce recrystallization and refine the structure in a short time. Figure 4The X-ray diffraction (XRD) patterns of magnesium alloy wires before and after the electric pulse annealing treatment obtained in Example 2 show that the intensity of the (0002) basal plane diffraction peak of the sample was significantly reduced after the electric pulse annealing treatment, and the basal plane texture was significantly weakened. This indicates that the pulse current promoted the randomization of grain orientation and helped to homogenize the texture. Figure 5 The (0001) pole figure of the magnesium alloy wire after cold drawing in step 5 of Example 2 shows that the c-axis of most grains in the cold-drawn sample tends to be parallel to the ND direction, the basal texture is significant, and the maximum strength of the (0001) pole figure is 8.08 mrd.

[0035] Figure 6 The (0001) pole figure of the magnesium alloy wire after the electric pulse annealing treatment in step 5 of Example 2 shows that the c-axis direction of the grains in the sample deviates from the original orientation parallel to ND and tilts towards DD or TD, resulting in a significant reduction in the strength of the basal texture. The maximum strength of the (0001) pole figure is 5.35 mrd.

[0036] Figure 7 The diagram shows the engineering stress-strain curves of magnesium alloy wires under different treatment conditions. It can be seen that the wires in Example 3, after being annealed by electric pulse, exhibited the best strength-plasticity synergy, with a tensile strength as high as 321 MPa and an elongation after fracture as high as 28%, which is significantly better than the performance of samples after traditional heat treatment.

[0037] Conclusion: This invention proposes a high-strength and high-toughness magnesium alloy wire based on electro-pulse annealing and its preparation method, which has significant advantages such as advanced technology, high production efficiency, and low cost. This process achieves efficient microstructure control through rapid electro-pulse annealing, inducing recrystallization and refining grains in a short time. The prepared magnesium alloy wire has a uniform microstructure and stable properties, with an average grain size of 2–4 μm. Test results from the examples show that the tensile strength of the prepared magnesium alloy wire is 310–360 MPa, the elongation after fracture is 25%–33%, and the Vickers microhardness is 85–103 HV. 1.0 It has excellent overall performance, is suitable for large-scale continuous production, and has broad prospects for industrial applications.

[0038] It should be noted that the embodiments described in this invention are merely preferred embodiments of the invention, intended to clearly illustrate the technical content of the invention and facilitate understanding and implementation by those skilled in the art, and do not constitute a limitation on the scope of protection of this invention. For those skilled in the art, various modifications, substitutions, adjustments, combinations, or optimizations can be made based on the disclosure of this invention without departing from the core principles and technical concept of this invention. These equivalent technical solutions should all be considered to fall within the protection scope of this invention.

Claims

1. A method for preparing high-strength and high-toughness magnesium alloy wire based on electrical pulse annealing, characterized in that... Includes the following steps: (1) Select magnesium alloy wire with a diameter of 2 mm as raw material; (2) The raw material obtained in step (1) is subjected to homogenization annealing treatment, and then the surface of the wire is polished. (3) The material obtained in step (2) is subjected to three consecutive cold drawing processes; (4) Perform electrical pulse annealing on the cold-drawn wire obtained in step (3); (5) Repeat steps (3) to (4) 1 to 3 times until a wire with a diameter of 1.00 to 1.43 mm is obtained.

2. The method for preparing high-strength and high-toughness magnesium alloy wire based on electro-pulse annealing according to claim 1, characterized in that... Includes the following steps: (1) Raw material preparation Magnesium alloy wire with a diameter of 2mm was selected as the raw material; (2) Homogenization annealing Magnesium alloy wire was placed in a muffle furnace for homogenization annealing. The power supply to the muffle furnace was turned on, and the temperature was raised to 300-350 °C and held for 2-2.5 h. The power supply to the muffle furnace was turned off, and the magnesium alloy wire was taken out and cooled to room temperature in the air. (3) Three-pass cold drawing After homogenization and annealing, the surface of the wire is polished with 400-grit sandpaper to make it smooth. The polished magnesium alloy wire is placed in a steel drawing die. Before each cold drawing, the wire and the die are lubricated with a lubricant. (4) Intermediate annealing Magnesium alloy wires obtained by three cold drawing processes were placed between the two electrodes of a bidirectional pulse power supply for electro-pulse annealing. Both ends of the wires were connected to electric clamps, one of which was connected to the positive pulse current output electrode of the pulse power supply, and the other was connected to the negative pulse current output electrode of the pulse power supply. The pulse voltage of the electro-pulse annealing process was 60–120 V, the pulse frequency was 100–200 Hz, the pulse width was 35–45 μs, and the processing time was 40–60 s. After annealing, the wires were cooled to room temperature in air. (5) Repeated processing Repeat steps (3) to (4) 1 to 3 times until a wire with a diameter of 1.00 to 1.43 mm is obtained.

3. The method for preparing high-strength and high-toughness magnesium alloy wire based on electro-pulse annealing according to claim 2, characterized in that: The magnesium alloy wire is AZ31 alloy, with a composition of Al 2.5–3.5 wt.%, Zn 0.6–1.2 wt.%, Mn 0.2–0.4 wt.%, and the balance being Mg.

4. The method for preparing high-strength and high-toughness magnesium alloy wire based on electro-pulse annealing according to claim 2, characterized in that: Step (3) is as follows: Start the drawing machine and perform three cold drawing processes at room temperature. The drawing speed is 2 to 4 m / min, the deformation per pass is 10%, and the cumulative deformation is 30%.

5. A high-strength and high-toughness magnesium alloy wire prepared by the preparation method according to any one of claims 1 to 4, based on electrical pulse annealing treatment.

6. The high-strength and high-toughness magnesium alloy wire based on electro-pulse annealing according to claim 5, characterized in that: The average grain size of the magnesium alloy wire is 2–4 μm, and its room temperature mechanical properties are: tensile strength of 310–360 MPa, elongation after fracture of 25%–33%, and microhardness of 85–103 HV.

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