A low-cost, high-performance magnesium alloy wire and its preparation method

Abstract

This invention relates to a low-cost, high-performance magnesium alloy wire and its preparation method, belonging to the field of metal processing technology. The invention involves sequentially homogenizing, extruding, and annealing a magnesium alloy ingot, followed by multi-pass drawing within a specific temperature range. After multiple peeling processes, a magnesium alloy wire with a diameter of 1.20 mm and tensile strength, yield strength, and elongation of 285 MPa~304 MPa, 260 MPa~282 MPa, and 3.8%~9.3%, respectively, exhibits a uniform microstructure and stable performance. This invention overcomes the problem of magnesium alloys being difficult to plastically deform or having small deformation amounts at room temperature, successfully preparing small-diameter magnesium alloy wire through a hot extrusion + hot drawing process. Simultaneously, this invention reduces the CRSS value of the non-basal slip system of magnesium alloys through the hot drawing process, activates the cylindrical and conical slip systems, and improves the plastic deformation capacity of magnesium alloys.

Description

Technical Field

[0001] This invention belongs to the field of metal processing technology, specifically relating to a low-cost, high-performance magnesium alloy wire and its preparation method. Background Technology

[0002] Magnesium alloys possess significant advantages such as low density, high specific strength, good biocompatibility, and excellent electromagnetic shielding, making them ideal weight-reducing structural materials for industrial applications and holding broad promise in alleviating the energy crisis. Among them, the AX / AXM series of magnesium alloys exhibits low cost, excellent extrusion performance, heat resistance, rapid age hardening effect, and a synergistic effect of high strength and plasticity, making them a highly promising magnesium alloy series. The drawing process can produce welding wires with smooth, clean surfaces, few defects, and extremely small diameter tolerances (typically ±0.01 mm), and optimizes the microstructure and mechanical properties of the welding wire, laying the material foundation for obtaining high-quality, high-performance, and highly stable magnesium alloy welded joints.

[0003] However, magnesium alloys have limited plastic deformation capacity at room temperature, requiring careful design of the deformation amount per drawing pass and intermediate annealing process to eliminate work hardening, restore plasticity, and ensure smooth continuous drawing. For example, patent CN117926093A discloses a magnesium alloy wire for arc additive manufacturing and its preparation method, which uses continuous extrusion and cold drawing to prepare magnesium alloy wires with diameters of 1.4mm to 1.6mm. After each drawing pass, a heat treatment at 200℃ to 210℃ for 1 to 2.5 hours is required. Patent CN110193525A discloses a method for rapidly preparing fine-grained and ultra-fine magnesium alloy wires based on a drawing process. This method uses a combination of high-temperature hot drawing and room-temperature cold drawing to prepare fine-grained magnesium alloy wires with diameters below 1.0mm and ultra-fine magnesium alloy wires with diameters of 0.10mm. After every 3 to 5 cold drawing passes, annealing at 350℃ to 400℃ for 5 to 10 minutes is required. Patent CN115323232A discloses a controllable dissolution method for magnesium alloy wire and its preparation. The method involves hot extrusion followed by cold drawing to prepare Mg-14Li-0.8Al-0.5Cu wire. Stress-relief annealing is performed after every 2-6 drawing passes, with a holding temperature of 200℃-380℃ and a holding time of 10-30 minutes. Compared to cold drawing, hot drawing can activate more non-basal slip systems, improve plasticity, reduce cracks, and increase production efficiency.

[0004] With the rapid development of additive manufacturing and the demand for production of complex magnesium alloy parts, it is of great significance to study suitable forming processes and deformation parameters for preparing AX / AXM series magnesium alloy welding wires. Therefore, it is necessary to provide an AX / AXM series magnesium alloy wire suitable for arc additive manufacturing and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a low-cost, high-performance magnesium alloy wire and its preparation method. This preparation method can overcome the problem that magnesium alloys are difficult to plastically deform at room temperature, improve production efficiency, and have good strength and plasticity. Moreover, the prepared magnesium alloy wire has uniform composition and structure and good surface quality.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of this invention provides a method for preparing low-cost, high-performance magnesium alloy wire, comprising the following steps:

[0008] (1) Homogenization treatment: Prepare cast alloy of Φ (115~180) mm × (200~800) mm as raw material, perform homogenization treatment, after homogenization treatment, quench in water at 65℃~90℃, and then machine 5mm~20mm off the surface to remove impurities and oxide layer.

[0009] (2) Extrusion deformation: Hot extrusion is carried out using a reverse extrusion press with an extrusion ratio of (22~40):1. Before extrusion, the billet is preheated to 450℃~480℃ for 30min~60min. The extrusion cylinder and extrusion die are preheated to 400℃~430℃. The magnesium alloy rods obtained after extrusion are air-cooled and have a diameter of 6mm~10mm.

[0010] (3) Drawing deformation: The extruded bar is annealed and used as the drawing base material. The base material is passed through a straightening machine and then passed into an induction heating furnace for multiple hot drawing to obtain Φ1.25mm~1.4mm magnesium alloy wire. The wire is naturally air-cooled after each drawing. No intermediate annealing treatment is performed during the drawing process.

[0011] (4) Peeling process: After 2 to 6 peeling processes, Φ1.20mm magnesium alloy wire is obtained, which is then tightly wound using a 270-type welding wire reel and vacuum packaged.

[0012] In step (1) above, the chemical composition (wt.%) of the as-cast alloy is Al: 5~6.5, Ca: 1.4~2.5, Mn: 0.35~0.5, Fe≤0.005, Cu≤0.008, Ni≤0.005, the content of other individual impurities ≤0.02wt.%, the total amount of impurities ≤0.3wt.%, and the balance of Mg.

[0013] In step (1) above, the temperature for homogenization treatment of the ingot is 480℃~530℃ and the time is 12h~25h.

[0014] In step (2) above, the extrusion temperature is 365℃~400℃ and the extrusion speed is 0.2mm / s~0.4mm / s.

[0015] In step (3) above, the annealing temperature is 350℃~500℃, preferably 450℃~500℃, the annealing time is 30min~120min, preferably 30min~60min, and furnace cooling is used after annealing. The elongation of the bar is 7.44%~9.53%.

[0016] In step (3) above, the hot drawing temperature is 400℃~500℃, the deformation per pass is 15%~25%, the drawing speed is 5m / min~30m / min, and the cumulative hot drawing passes are 15~22.

[0017] In step (3) above, a vertical drawing machine is used, and the drawing die is an alloy steel die of different sizes.

[0018] In step (3) above, MoS2 grease is used as a lubricant, which is evenly applied to the surface of the magnesium alloy wire and the mold opening, and the lubricant is replenished in time.

[0019] The second aspect of this invention provides a low-cost, high-performance magnesium alloy wire, prepared using the method described above. The prepared magnesium alloy wire has a diameter of 1.20 mm, tensile strength, yield strength, and elongation of 285 MPa~304 MPa, 260 MPa~282 MPa, and 3.8%~9.3%, respectively. It has a uniform microstructure and stable performance, and can be used in welding and fused wire additive manufacturing. The magnesium alloy wire has a smooth surface and a dimensional tolerance of +0.01 mm to -0.04 mm, meeting the requirements of the national standard GB / T 41112-2021 Magnesium and Magnesium Alloy Welding Wire.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The present invention adopts a low-cost Mg-Al-Ca-Mn alloy system. Compared with traditional high-strength and high-toughness magnesium alloys, which usually add a large amount of rare earth elements (such as Gd, Y, La, etc.), only aluminum, calcium, manganese and other inexpensive and abundant alloy elements are used, and the raw material cost can be reduced by more than 50%.

[0022] (2) This invention overcomes the problem that magnesium alloys are difficult to plastically deform or have small deformation at room temperature, and successfully prepares small-diameter magnesium alloy wires through hot extrusion + hot drawing process. Hot extrusion subjectes the magnesium alloy billet to triaxial compressive stress, resulting in uniform metal flow and improved processing performance. The tensile strength, yield strength, elongation, and hardness of the extruded bar are 265MPa~276MPa, 189MPa~208MPa, 4.9%~6.8%, and 63.1HV~69.4HV, respectively.

[0023] (3) In the preparation method of this invention, the hot drawing process reduces the CRSS value of the non-basal slip system of magnesium alloy, activates the cylindrical and conical slip systems, and improves the plastic deformation capacity of magnesium alloy. When the drawing temperature is 400℃~500℃, small-diameter rare earth magnesium alloy wires can be prepared with an inter-pass deformation of 15%~25%, without the need for inter-pass annealing, which improves production efficiency, reduces production costs, and is suitable for large-scale mass production. The prepared Φ1.20mm magnesium alloy wire has a uniform structure and a smooth surface, meeting the requirements of the national standard GB / T 41112-2021 Magnesium and Magnesium Alloy Welding Wire.

[0024] (4) The magnesium alloy wire prepared by this invention has good strength and plasticity. During the drawing deformation process, the fine and dispersed (Mg,Al)2Ca phase can not only effectively hinder the movement of dislocations and form dislocation entanglements, thus increasing the deformation resistance, but also pin the recrystallization grain boundaries to refine the recrystallized grains. Under the combined effect of work hardening, second-phase strengthening, and dynamic recrystallization, the strength of the magnesium alloy wire is improved. The tensile strength, yield strength, and elongation of the prepared magnesium alloy wire are 285MPa~304MPa, 260MPa~282MPa, and 3.8%~9.3%, respectively, and it can be used in welding and fused wire additive manufacturing. Attached Figure Description

[0025] Figure 1 These are photographs of the grain morphology of rare earth magnesium alloy wires of different diameters prepared by hot drawing in Example 1 of the present invention; wherein, (a) is Φ7.2mm, (b) is Φ4.9mm, (c) is Φ3.3mm, and (d) is Φ1.2mm.

[0026] Figure 2 These are photographs of the grain morphology of rare earth magnesium alloy wires of different diameters prepared by hot drawing in Example 2 of the present invention; wherein, (a) is Φ7.2mm, (b) is Φ4.9mm, (c) is Φ3.3mm, and (d) is Φ1.2mm.

[0027] Figure 3 These are photographs of the grain morphology of rare earth magnesium alloy wires of different diameters prepared by hot drawing in Example 3 of the present invention; wherein, (a) is Φ7.2mm, (b) is Φ4.9mm, (c) is Φ3.3mm, and (d) is Φ1.2mm. Detailed Implementation

[0028] This invention provides a method for preparing low-cost, high-performance magnesium alloy wire, comprising the following steps:

[0029] (1) Homogenization treatment: Prepare a cast alloy with a diameter of Φ (115~180) mm × (200~800) mm, and the composition by mass percentage includes Al 5wt%~6.5wt%, Ca 1.4wt%~2.5wt%, Mn 0.35wt%~0.5wt%, Fe≤0.005wt%, Cu≤0.008wt%, Ni≤0.005wt%, other individual impurities ≤0.02wt.%, total impurities ≤0.3wt.%, and the balance being Mg. Homogenize it at 480℃~530℃ for 12h~25h, then quench it in water at 65℃~90℃, and then machine 5mm~20mm off the surface to remove impurities and oxide layer to obtain the billet.

[0030] (2) Extrusion deformation: The billet is preheated at 450℃~480℃ for 30min~60min, and the extrusion cylinder and extrusion die are preheated to 400℃~430℃. Hot extrusion is carried out at 365℃~400℃ using a reverse extrusion press at an extrusion speed of 0.2mm / s~0.4mm / s, where the extrusion ratio is (22~40):1. Magnesium alloy extruded bars with a diameter of 6mm~10mm are obtained after extrusion, and the extruded bars are air-cooled. The tensile strength of the extruded bars is 265MPa~276MPa, the yield strength is 189MPa~208MPa, the elongation is 4.9%~6.8%, and the hardness is 63.1HV~69.4HV.

[0031] (3) Drawing deformation: The extruded bar is annealed at 350℃~500℃ for 30min~120min, and then furnace cooled to obtain a drawing master stock with an elongation of 7.44%~9.53%. The drawing master stock is passed through a straightening machine and then put into an induction heating furnace. A vertical disc drawing machine is used, with alloy steel dies of different sizes as drawing dies. MoS2 grease is used as a lubricant and is evenly applied to the surface of the magnesium alloy wire and the die opening. Hot drawing is performed at 400℃~500℃ at a speed of 5m / min~30m / min for 15~22 passes. Lubricant is replenished in time during the drawing process. The wire is naturally air-cooled after each pass to obtain Φ1.25mm~1.4mm magnesium alloy wire. The deformation amount of each pass is 15%~25%. No intermediate annealing treatment is performed during the drawing process.

[0032] (4) Peeling process: After 2 to 6 peeling processes, Φ1.20mm magnesium alloy wire is obtained, which is then tightly wound using a 270-type welding wire reel and vacuum packaged.

[0033] This invention also provides a low-cost, high-performance magnesium alloy wire, prepared using the above method. The prepared magnesium alloy wire has a diameter of 1.20 mm, tensile strength, yield strength, and elongation of 285 MPa~304 MPa, 260 MPa~282 MPa, and 3.8%~9.3%, respectively. It has a uniform microstructure and stable performance, and can be used in welding and fused wire additive manufacturing. The magnesium alloy wire has a smooth surface and a dimensional tolerance of +0.01 mm to -0.04 mm, meeting the requirements of the national standard GB / T 41112-2021 Magnesium and Magnesium Alloy Welding Wire.

[0034] In this embodiment of the invention, the chemical composition (wt.%) of the as-cast alloy is Al: 5~6.5, Ca: 1.4~2.5, Mn: 0.35~0.5, Fe≤0.005, Cu≤0.008, Ni≤0.005, the content of other individual impurities ≤0.02wt.%, the total amount of impurities ≤0.3wt.%, and Mg as the balance.

[0035] In this embodiment of the invention, the tensile test was conducted on a CMT5105 universal testing machine at a tensile speed of 2 mm / min, and the average value of three tensile specimens in each group was selected as the final experimental data.

[0036] This invention will further describe in detail a low-cost, high-performance magnesium alloy wire and its preparation method with reference to the accompanying drawings and specific embodiments. It should be noted that these specific embodiments are merely illustrative and do not constitute any limitation on the invention.

[0037] Example 1:

[0038] This embodiment provides a method for preparing low-cost, high-performance magnesium alloy wire, including the following steps:

[0039] (1) Homogenization treatment: Prepare a cast alloy with a diameter of Φ150mm×(300~600)mm, and the composition by mass percentage includes Al6%, Ca2%, Mn0.4%, Fe≤0.005%, Cu≤0.008%, Ni≤0.005%, other individual impurities ≤0.02wt.%, total impurities ≤0.3wt.%, and the balance being Mg. Homogenize it at 510℃ for 12h, then quench it in water at 65℃~90℃, and then machine 5mm off the surface to remove impurities and oxide layer to obtain the billet.

[0040] (2) Extrusion deformation: The billet is preheated at 450℃~480℃ for 40 minutes, the extrusion cylinder and extrusion die are preheated to 400℃~430℃, and hot extrusion is carried out at 380℃ with an extrusion speed of 0.3mm / s using a reverse extrusion press. The extrusion ratio is 28:1. Magnesium alloy extruded bars with a diameter of 10mm are obtained by extrusion, and the extruded bars are air-cooled.

[0041] (3) Drawing deformation: The extruded bar is annealed at 450℃ for 60 min, and then furnace cooled to obtain the drawing master stock. The drawing master stock is passed through a straightening machine and then into an induction heating furnace. A vertical disc drawing machine is used, with alloy steel dies of different sizes as drawing dies. MoS2 grease is used as a lubricant, which is evenly applied to the surface of the magnesium alloy wire and the die opening. Hot drawing is performed at 400℃ and a speed of 20 m / min for 19 to 22 passes. Lubricant is replenished in time during the drawing process. The wire is naturally air-cooled after each pass to obtain Φ1.25mm~1.4mm magnesium alloy wire. The deformation amount of each pass is 15%~25%. No intermediate annealing treatment is performed during the drawing process.

[0042] (4) Peeling process: After 2 to 6 peeling processes, Φ1.20mm magnesium alloy wire is obtained, which is then tightly wound using a 270-type welding wire reel and vacuum packaged.

[0043] In this embodiment, the microstructures of magnesium alloy wires with different diameters were prepared by hot drawing. Figure 1 .Depend on Figure 1 As the total deformation increases, the grain size gradually decreases from 24.1 μm to 13.7 μm. The spherical Mg2Ca second phase breaks down and its size decreases, while the (Mg,Al)2Ca second phase, which is streamlined along the drawing direction, is more dispersed in the matrix. The magnesium alloy wire finally obtained in this embodiment has a diameter of 1.20 mm, a smooth surface, a dimensional tolerance of +0.01 mm to -0.04 mm, a uniform microstructure, and stable performance. It can be used in welding and fused wire additive manufacturing. The wire meets the requirements of the national standard GB / T 41112-2021 Magnesium and Magnesium Alloy Welding Wire.

[0044] Example 2:

[0045] This embodiment provides a method for preparing low-cost, high-performance magnesium alloy wire, including the following steps:

[0046] (1) Homogenization treatment: Prepare a cast alloy with a diameter of Φ150mm×(300~600)mm, and the composition by mass percentage includes Al 5%, Ca 2.5%, Mn 0.5%, Fe≤0.005%, Cu≤0.008%, Ni≤0.005%, other individual impurity content ≤0.02wt.%, total impurity ≤0.3wt.%, and the balance being Mg. Homogenize it at 510℃ for 24h, then quench it in water at 65℃~90℃, and then machine 5mm off the surface to remove impurities and oxide layer to obtain the billet.

[0047] (2) Extrusion deformation: The billet is preheated at 450℃~480℃ for 40 minutes, the extrusion cylinder and extrusion die are preheated to 400℃~430℃, and hot extrusion is carried out at 380℃ with an extrusion speed of 0.3mm / s using a reverse extrusion press. The extrusion ratio is 28:1. Magnesium alloy extruded bars with a diameter of 10mm are obtained by extrusion, and the extruded bars are air-cooled.

[0048] (3) Drawing deformation: The extruded bar is annealed at 500℃ for 30 min, and then furnace cooled to obtain the drawing master material. The drawing master material is passed through a straightening machine and then into an induction heating furnace. A vertical disc drawing machine is used, with alloy steel dies of different sizes as drawing dies. MoS2 grease is used as a lubricant and is evenly applied to the surface of the magnesium alloy wire and the die opening. Hot drawing is performed at 450℃ and a speed of 20 m / min for 17 to 20 passes. Lubricant is replenished in time during the drawing process. The wire is naturally air-cooled after each pass to obtain Φ1.25mm~1.4mm magnesium alloy wire. The deformation amount of each pass is 15%~25%. No intermediate annealing treatment is performed during the drawing process.

[0049] (4) Peeling process: After 2 to 6 peeling processes, Φ1.20mm magnesium alloy wire is obtained, which is then tightly wound using a 270-type welding wire reel and vacuum packaged.

[0050] In this embodiment, the microstructures of magnesium alloy wires with different diameters were prepared by hot drawing. Figure 2 .Depend on Figure 2 It is evident that a large number of fine granular second phases are distributed along the drawing direction, which effectively hinders dislocation movement and provides more nucleation sites for dynamic recrystallization. As the total deformation increases, the grain size gradually becomes finer, and the number of twins gradually decreases.

[0051] Example 3:

[0052] This embodiment provides a method for preparing low-cost, high-performance magnesium alloy wire, including the following steps:

[0053] (1) Homogenization treatment: Prepare a cast alloy with a diameter of Φ150mm×(300~600)mm, and the composition by mass percentage includes Al6.5%, Ca1.5%, Mn0.4%, Fe≤0.005%, Cu≤0.008%, Ni≤0.005%, other individual impurities ≤0.02wt.%, total impurities ≤0.3wt.%, and the balance being Mg. Homogenize it at 510℃ for 24h, then quench it in water at 65℃~90℃, and then machine 5mm off the surface to remove impurities and oxide layer to obtain the billet.

[0054] (2) Extrusion deformation: The billet is preheated at 450℃~480℃ for 40 minutes, the extrusion cylinder and extrusion die are preheated to 400℃~430℃, and hot extrusion is carried out at 380℃ with an extrusion speed of 0.3mm / s using a reverse extrusion press. The extrusion ratio is 40:1. Magnesium alloy extruded bars with a diameter of 8.4mm are obtained by extrusion, and the extruded bars are air-cooled.

[0055] (3) Drawing deformation: The extruded bar is annealed at 450℃ for 60 min, and then furnace cooled to obtain the drawing master material. The drawing master material is passed through a straightening machine and then into an induction heating furnace. A vertical disc drawing machine is used, with alloy steel dies of different sizes as drawing dies. MoS2 grease is used as a lubricant and is evenly applied to the surface of the magnesium alloy wire and the die opening. Hot drawing is performed at 500℃ and a speed of 20 m / min for 15 to 18 passes. Lubricant is replenished in time during the drawing process. The wire is naturally air-cooled after each pass to obtain Φ1.25mm~1.4mm magnesium alloy wire. The deformation amount of each pass is 15%~25%. No intermediate annealing treatment is performed during the drawing process.

[0056] (4) Peeling process: After 2 to 6 peeling processes, Φ1.20mm magnesium alloy wire is obtained, which is then tightly wound using a 270-type welding wire reel and vacuum packaged.

[0057] In this embodiment, the microstructures of magnesium alloy wires with different diameters were prepared by hot drawing. Figure 3 .Depend on Figure 3 It can be seen that as the total deformation increases, the microstructure of the alloy exhibits the same trend as in other embodiments.

[0058] Comparative Example 1:

[0059] This comparative example provides a method for preparing magnesium alloy wire, including the following steps:

[0060] (1) Homogenization treatment: Prepare a cast alloy with a diameter of Φ150mm×(300~600)mm, and the composition by mass percentage includes Al8%, Ca3.5%, Mn0.4%, Fe≤0.005%, Cu≤0.008%, Ni≤0.005%, other individual impurities ≤0.02wt.%, total impurities ≤0.3wt.%, and the balance being Mg. Homogenize it at 510℃ for 24h, then quench it in water at 65℃~90℃, and then machine 5mm off the surface to remove impurities and oxide layer to obtain the billet.

[0061] (2) Extrusion deformation: The billet is preheated at 450℃~480℃ for 40 minutes, the extrusion cylinder and extrusion die are preheated to 400℃~430℃, and hot extrusion is carried out at 380℃ with an extrusion speed of 0.3mm / s using a reverse extrusion press. The extrusion ratio is 28:1. Magnesium alloy extruded bars with a diameter of 10mm are obtained after extrusion.

[0062] In this comparative example, the composition of the as-cast alloy uses a high content of Al and Ca elements. A large amount of hard and brittle (Mg,Al)2Ca phase will be generated in the alloy, which hinders dislocation movement, induces crack propagation, and results in a low elongation of the alloy under this composition, which is not conducive to drawing deformation.

[0063] Comparative Example 2:

[0064] This comparative example provides a method for preparing low-cost, high-performance magnesium alloy wire, comprising the following steps:

[0065] (1) Homogenization treatment: Prepare a cast alloy with a diameter of Φ150mm×(300~600)mm, and the composition by mass percentage includes Al6.0%, Ca2.0%, Mn0.4%, Fe≤0.005%, Cu≤0.008%, Ni≤0.005%, other individual impurities ≤0.02wt.%, total impurities ≤0.3wt.%, and the balance being Mg. Homogenize it at 510℃ for 24h, then quench it in water at 65℃~90℃, and then machine 5mm off the surface to remove impurities and oxide layer to obtain the billet.

[0066] (2) Extrusion deformation: The billet is preheated at 450℃~480℃ for 40 minutes, the extrusion cylinder and extrusion die are preheated to 400℃~430℃, and hot extrusion is carried out at 380℃ with an extrusion speed of 0.3mm / s using a reverse extrusion press. The extrusion ratio is 28:1. Magnesium alloy extruded bars with a diameter of 10mm are obtained by extrusion, and the extruded bars are air-cooled.

[0067] (3) Drawing deformation: The extruded bar is annealed at 300℃ for 30 min and then furnace cooled to obtain the drawing master material. The drawing master material is passed through a straightening machine and then put into an induction heating furnace. A vertical plate drawing machine is used, with alloy steel dies of different sizes as drawing dies. MoS2 grease is used as a lubricant and is evenly applied to the surface of the magnesium alloy wire and the die opening. The wire is hot drawn at 400℃ at a speed of 20 m / min. Lubricant is replenished in time during the drawing process, and the wire is naturally air-cooled after each drawing pass.

[0068] In this comparative example, the annealing temperature of the extruded bar was lower, which reduced the plastic deformation capacity of the alloy. As a result, the alloy reached the drawing limit after 6 to 8 hot drawing passes, and magnesium alloy wire with a diameter of Φ4.19mm to 5.23mm was obtained.

[0069] Comparative Example 3:

[0070] This comparative example provides a method for preparing low-cost, high-performance magnesium alloy wire, comprising the following steps:

[0071] (1) Homogenization treatment: Prepare a cast alloy with a diameter of Φ150mm×(300~600)mm, and the composition by mass percentage includes Al6.0%, Ca2.0%, Mn0.4%, Fe≤0.005%, Cu≤0.008%, Ni≤0.005%, other individual impurities ≤0.02wt.%, total impurities ≤0.3wt.%, and the balance being Mg. Homogenize it at 510℃ for 24h, then quench it in water at 65℃~90℃, and then machine 5mm off the surface to remove impurities and oxide layer to obtain the billet.

[0072] (2) Extrusion deformation: The billet is preheated at 450℃~480℃ for 40min, and the extrusion cylinder and extrusion die are preheated to 400℃~430℃. Hot extrusion is carried out at 380℃ and an extrusion speed of 0.3mm / s using a reverse extrusion press. The extrusion ratio is 28:1. Magnesium alloy extruded bars with a diameter of 10mm are obtained after extrusion. The extruded bars are then air-cooled. The tensile strength of the extruded bars is 265MPa~276MPa, the yield strength is 189MPa~208MPa, the elongation is 4.9%~6.8%, and the hardness is 63.1HV~69.4HV.

[0073] (3) Drawing deformation: The extruded bar is annealed at 450℃ for 60 min and then furnace cooled to obtain a drawing base material with an elongation of 7.44%~9.53%. The drawing base material is passed through a straightening machine and then put into an induction heating furnace. A vertical disc drawing machine is used, with alloy steel dies of different sizes as drawing dies. MoS2 grease is used as a lubricant and is evenly applied to the surface of the magnesium alloy wire and the die opening. Hot drawing is carried out at 350℃ at a speed of 10 m / min. Lubricant is replenished in time during the drawing process, and the wire is naturally air-cooled after each drawing pass.

[0074] In this comparative example, the hot drawing temperature is lower, the work hardening and second phase strengthening effects of the alloy are more significant, and the deformation resistance of the alloy is increased. As a result, at this temperature, only a small amount of deformation (10%~15%) can be drawn. The alloy is hot drawn 7~10 times in total to reach the drawing limit and obtain magnesium alloy wire with Φ3.4mm~4.7mm.

[0075] Comparative Example 4:

[0076] This comparative example provides a method for preparing low-cost, high-performance magnesium alloy wire, comprising the following steps:

[0077] (1) Homogenization treatment: Prepare a cast alloy with a diameter of Φ150mm×(300~600)mm, and the composition by mass percentage includes Al6.0%, Ca2.0%, Mn0.4%, Fe≤0.005%, Cu≤0.008%, Ni≤0.005%, other individual impurities ≤0.02wt.%, total impurities ≤0.3wt.%, and the balance being Mg. Homogenize it at 510℃ for 24h, then quench it in water at 65℃~90℃, and then machine 5mm off the surface to remove impurities and oxide layer to obtain the billet.

[0078] (2) Extrusion deformation: The billet is preheated at 450℃~480℃ for 40 minutes, the extrusion cylinder and extrusion die are preheated to 400℃~430℃, and hot extrusion is carried out at 380℃ with an extrusion speed of 0.5mm / s using a reverse extrusion press, wherein the extrusion ratio is 48:1.

[0079] In this comparative example, the alloy is not suitable for plastic processing with a high extrusion ratio. During the extrusion process, the work of plastic deformation is converted into heat, which causes microcracks to appear on the surface of the alloy bar, making it impossible to perform drawing deformation.

[0080] The mechanical properties of different embodiments and comparative examples were tested during different preparation processes, and the results are shown in Table 1.

[0081] Table 1. Test results of mechanical properties of magnesium alloy bars and wires in Examples 1-3 and Comparative Examples 1-2;

[0082] ;

[0083] All aspects of this invention not described in detail are prior art. Although the invention has been described in detail through the above exemplary embodiments, those skilled in the art should understand that the invention is not limited to the specific embodiments disclosed. Without departing from the principles of the invention, those skilled in the art can make various improvements and modifications to the invention. These simple modifications, equivalent substitutions, or further evolutions based on the technical essence of the invention should all be considered to fall within the protection scope of this invention.

Claims

1. A method for preparing low-cost, high-performance magnesium alloy wire, characterized in that, Includes the following steps: S1. Homogenization treatment: The cast magnesium alloy raw material is homogenized and then quenched. Then, surface impurities and oxide layers are removed by turning to obtain the billet. S2. Extrusion deformation: The preheated billet is hot-extruded under an extrusion ratio of (22~40):1 and then air-cooled to obtain magnesium alloy rods; S3. Drawing Deformation: After annealing the magnesium alloy bar, a drawing master material is obtained; the drawing master material is passed through a straightening machine and then put into an induction heating furnace for hot drawing to obtain Φ1.25mm~1.4mm magnesium alloy wire; wherein, after each drawing pass, it is naturally air-cooled, and no intermediate annealing treatment is performed during the drawing process; S4. Peeling process: The magnesium alloy wire is peeled to obtain a Φ1.20mm magnesium alloy wire.

2. The method for preparing a low-cost, high-performance magnesium alloy wire according to claim 1, characterized in that, The composition of the cast magnesium alloy, by mass percentage, includes Al 5wt%~6.5wt%, Ca 1.4wt%~2.5wt%, Mn 0.35wt%~0.5wt%, Fe≤0.005wt%, Cu≤0.008wt%, Ni≤0.005wt%, other individual impurities ≤0.02wt.%, total impurities ≤0.3wt.%, and the balance being Mg.

3. The method for preparing a low-cost, high-performance magnesium alloy wire according to claim 1, characterized in that, In S1, the homogenization treatment temperature is 480℃~530℃, and the time is 12h~25h.

4. The method for preparing a low-cost, high-performance magnesium alloy wire according to claim 1, characterized in that, In S1, quenching is performed in water at 65℃~90℃. Remove 5mm to 20mm from the surface by turning.

5. The method for preparing a low-cost, high-performance magnesium alloy wire according to claim 1, characterized in that, In S2, before extrusion, preheat to 450℃~480℃ for 30min~60min; The extrusion cylinder and extrusion die are preheated to 400℃~430℃; The diameter of the magnesium alloy rod is 6mm~10mm.

6. The method for preparing a low-cost, high-performance magnesium alloy wire according to claim 1, characterized in that, In S2, the extrusion temperature is 365℃~400℃, and the extrusion speed is 0.2mm / s~0.4mm / s.

7. The method for preparing a low-cost, high-performance magnesium alloy wire according to claim 1, characterized in that, In S3, the annealing temperature is 350℃~500℃, and the annealing time is 30min~120min; After annealing, furnace cooling was performed to obtain a drawn base material with an elongation of 7.44% to 9.53%.

8. The method for preparing a low-cost, high-performance magnesium alloy wire according to claim 1, characterized in that, In S3, the hot drawing temperature is 400℃~500℃, the deformation per pass is 15%~25%, the drawing speed is 5m / min~30m / min, and the cumulative hot drawing passes are 15~22.

9. The method for preparing a low-cost, high-performance magnesium alloy wire according to claim 1, characterized in that, MoS2 grease was used as a lubricant, which was evenly applied to the surface of the magnesium alloy wire and the die opening, and the lubricant was replenished in a timely manner.

10. A low-cost, high-performance magnesium alloy wire, prepared by the method described in any one of claims 1 to 9, characterized in that, The magnesium alloy wire has a tensile strength of 285MPa~304MPa, a yield strength of 260MPa~282MPa, and an elongation of 3.8%~9.3%.

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