A micro-alloyed magnesium alloy and a short-process preparation method and application thereof

Abstract

The present application relates to the field of metal materials, in particular to a kind of microalloyed magnesium alloy and its short process preparation method and application.The microalloyed magnesium alloy is composed of the following components by mass percentage: manganese: 0.2~0.7%, zinc: 0.2~0.5%, cerium: 0.1~0.3%, the rest is magnesium and inevitable impurities;The microstructure of the microalloyed magnesium alloy includes the structure of dynamic recrystallization grain and non-dynamic recrystallization region coexistence;Among them, the average grain size of dynamic recrystallization grain is 0.5~2 μm, and the volume fraction of dynamic recrystallization region is 20%~50%.The present application significantly reduces the cost of raw materials, effectively controls the microstructure of alloy, realizes the synergistic improvement of strength and plasticity, and the obtained magnesium alloy has good comprehensive mechanical properties, with yield strength ≥ 290MPa, elongation ≥ 8.5%.

Description

Technical Field

[0001] This invention relates to the field of metallic materials, specifically to a microalloyed magnesium alloy and its short-process preparation method and application. Background Technology

[0002] Magnesium alloys, as promising green structural materials, possess low density, high specific strength, high specific stiffness, and excellent damping and vibration reduction properties, making them highly potential applications in lightweight fields such as aerospace and transportation. However, magnesium alloys, especially wrought magnesium alloys, generally face common problems in practical large-scale applications, such as poor processability, low yield, high manufacturing costs, and insufficient absolute strength. These issues severely restrict their further promotion as a primary structural material.

[0003] To improve the strength and ductility of magnesium alloys, existing technologies mainly rely on significantly increasing the amount of alloying elements (such as aluminum and zinc) or introducing a high proportion of rare earth elements. While this "high alloying" approach can improve performance to some extent, it also introduces new challenges: on the one hand, the large addition of expensive alloying elements (especially rare earths) directly leads to a significant increase in raw material costs, and high alloy content is not conducive to the subsequent recycling and reuse of materials; on the other hand, high alloying element content easily forms coarse second phases in the alloy. These brittle phases can become the origin of microcracks, severely impairing the ductility of the material and potentially deteriorating its processing performance. Therefore, how to overcome the problem of ductility degradation caused by the pursuit of high strength while effectively controlling costs, and achieve a synergistic improvement in the strength and ductility of magnesium alloys, has become a key technological bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0004] This invention provides a microalloyed magnesium alloy, its short-process preparation method, and its application, to solve the problems of high cost caused by the addition of a large number of alloying elements in existing high-alloyed magnesium alloys, and the difficulty in synergistically improving strength and plasticity due to the formation of coarse second phase.

[0005] In a first aspect, the present invention provides a microalloyed magnesium alloy, wherein the microalloyed magnesium alloy is composed of the following components by mass percentage: manganese: 0.2~0.7%, zinc: 0.2~0.5%, cerium: 0.1~0.3%, with the balance being magnesium and unavoidable impurities; the microstructure of the microalloyed magnesium alloy comprises a structure in which dynamically recrystallized grains and non-dynamically recrystallized regions coexist; wherein the average grain size of the dynamically recrystallized grains is 0.5~2μm, and the volume fraction of the dynamically recrystallized regions is 20%~50%. As an example, the manganese content may be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, or within any range of the above values ​​(e.g., 0.2%~0.6%, 0.3%~0.5%); the zinc content may be 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, or within any range of the above values ​​(e.g., 0.2%~0.4%, 0.25%~0.35%); and the cerium content may be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, or within any range of the above values ​​(e.g., 0.1%~0.25%, 0.15%~0.2%).

[0006] In one optional embodiment, the microalloyed magnesium alloy is composed of the following components by mass percentage: 0.6-0.7% manganese, 0.4-0.5% zinc, 0.2-0.3% cerium, with the balance being magnesium and unavoidable impurities; Optionally, the total content of manganese, zinc, and cerium in the microalloyed magnesium alloy is ≤1.5 wt.%, preferably ≤1.2 wt.%; as an example, the total content can be 0.9 wt.%, 1.0 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, or within any range of the above values; Optionally, the content of unavoidable impurities is ≤0.05 wt.%; as an example, the impurity content may be 0.01 wt.%, 0.02 wt.%, 0.03 wt.%, 0.04 wt.%, 0.05 wt.%, or within any of the above values. And / or, the average grain size of the dynamically recrystallized grains is 1~2μm; And / or, the volume fraction of the dynamically recrystallized region is 30%~50%; And / or, the yield strength of the microalloyed magnesium alloy is ≥290MPa, preferably 290~335MPa; as an example, the yield strength can be 290MPa, 300MPa, 310MPa, 320MPa, 330MPa, 335MPa, or within any range of the above values ​​(e.g., 300~330MPa); And / or, the elongation of the microalloyed magnesium alloy is ≥8.5%, preferably 8.5% to 18%. As an example, the elongation may be 8.5%, 10.0%, 12.0%, 14.0%, 16.0%, 18.0%, or within any range of the above values ​​(e.g., 10.0% to 16.0%).

[0007] In a second aspect, the present invention also provides a short-process preparation method for microalloyed magnesium alloys as described in the first aspect, comprising the following steps: Obtain a magnesium alloy ingot; wherein the magnesium alloy ingot is composed of the following components by mass percentage: 0.2~0.7% manganese, 0.2~0.5% zinc, 0.1~0.3% cerium, with the balance being magnesium and unavoidable impurities; Magnesium alloy ingots are subjected to aging treatment and hot extrusion deformation in sequence; wherein the holding time of the aging treatment is ≥80h.

[0008] In an optional embodiment, after the hot extrusion deformation step, the hot-extruded alloy is further subjected to annealing treatment; optionally, the annealing temperature is 250~350℃, preferably 280~320℃; as an example, the annealing temperature can be 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, or within any range of the above values ​​(e.g., 280℃~320℃); when annealing treatment is performed, the holding time of the annealing treatment is 0~30min; as an example, the annealing holding time can be 0min (i.e., no annealing treatment), 5min, 10min, 15min, 20min, 25min, 30min, or within any range of the above values ​​(e.g., 10~30min) And / or, the heat preservation time of the aging treatment is 80~110h; as an example, the heat preservation time of the aging treatment can be 80h, 85h, 90h, 95h, 100h, 105h, 110h, or within any of the above values ​​(e.g., 80~96h). And / or, the aging treatment temperature is 150~250℃, preferably 180~220℃; as an example, the aging temperature can be 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, or within any range of the above values ​​(e.g., 180℃~220℃, 200℃~250℃); And / or, the temperature of the hot extrusion deformation is 250~350°C, preferably 280~320°C; as an example, the extrusion temperature can be 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, or within any range of the above values ​​(e.g., 280°C~320°C, 300°C~320°C). And / or, the extrusion ratio of the hot extrusion deformation is (15~40):1, preferably (25~30):1; as an example, the extrusion ratio can be 15:1, 20:1, 25:1, 28:1, 30:1, 35:1, 40:1, or within any of the above values ​​(e.g., (25~30):1, (28~30):1); And / or, the extrusion speed of the hot extrusion deformation is 1~10 mm / s, preferably 2~5 mm / s. As an example, the extrusion speed can be 1 mm / s, 2 mm / s, 3 mm / s, 4 mm / s, 5 mm / s, 6 mm / s, 7 mm / s, 8 mm / s, 9 mm / s, 10 mm / s, or within any range of the above values ​​(e.g., 2~5 mm / s, 1~2.8 mm / s).

[0009] In one optional implementation, after the aging treatment, a water cooling treatment is also performed; preferably, the water cooling process includes: water cooling to room temperature; And / or, before the hot extrusion deformation, the aged magnesium alloy ingot is preheated at 280~320℃ for 30~90min; as an example, the preheating temperature can be 280℃, 290℃, 300℃, 310℃, 320℃, or within any range of the above values ​​(e.g., 280℃~300℃); the preheating time can be 30min, 40min, 50min, 60min, 70min, 80min, 90min, or within any range of the above values ​​(e.g., 60min~90min). And / or, after the hot extrusion deformation, the process further includes the step of air cooling the alloy to room temperature.

[0010] In one optional embodiment, the magnesium alloy ingot is obtained through a melting and casting process; optionally, the melting and casting process includes the following steps: Weigh out the raw materials containing magnesium, zinc, manganese and cerium; The raw materials are smelted under a protective atmosphere to obtain a magnesium alloy melt; The magnesium alloy melt is refined. The refined melt is poured into a mold and cooled to obtain a magnesium alloy ingot.

[0011] In one optional embodiment, the raw materials are pure magnesium, pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy. And / or, the protective atmosphere is a mixture of carbon dioxide and sulfur hexafluoride; optionally, the volume ratio of carbon dioxide to sulfur hexafluoride in the mixture is (90~99):(10~1); as an example, the volume ratio can be 90:10, 92:8, 95:5, 97:3, 99:1, or within any of the above values ​​(e.g., 95:5~99:1); And / or, the refining process is to refine and remove slag by blowing in an inert gas; optionally, the inert gas includes, but is not limited to, nitrogen and / or argon. And / or, the casting includes, but is not limited to, gravity casting; And / or, the mold preheating temperature before casting is 280~320°C. As an example, the mold preheating temperature can be 280°C, 290°C, 300°C, 310°C, 320°C, or within any range of the above values ​​(e.g., 290°C~310°C).

[0012] In one optional embodiment, the smelting process includes: first, holding pure magnesium at 300-400°C for 30-90 minutes, then heating to 680-720°C to melt it into molten magnesium, and then adding the remaining raw materials that have been preheated at 180-250°C for 40-80 minutes; as an example, the preheating and holding temperature of the pure magnesium can be 300°C, 320°C, 340°C, 360°C, 380°C, 400°C, or within any range of the above values ​​(e.g., 300-320°C, 340°C-380°C); the preheating and holding time of the pure magnesium can be 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, or within any range of the above values. The preheating temperature of the pure magnesium can be 680℃, 690℃, 700℃, 710℃, 720℃, or within any range of the above values ​​(e.g., 680℃~690℃); the preheating temperature of the remaining raw materials can be 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, or within any range of the above values ​​(e.g., 180℃~200℃); the preheating time of the remaining raw materials can be 40min, 50min, 60min, 70min, 80min, or within any range of the above values ​​(e.g., 60min~80min). And / or, before the refining process, the melted material is stirred and kept at a temperature for 5 to 20 minutes; as an example, the holding time can be 5 minutes, 10 minutes, 15 minutes, 20 minutes, or within any of the above values ​​(e.g., 5 to 10 minutes). And / or, after the refining process, the process further includes a step of resting and keeping warm for 10 to 30 minutes. As an example, the resting time can be 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, or within any range of the above values ​​(e.g., 15 to 25 minutes).

[0013] Thirdly, the present invention also provides a magnesium alloy component comprising the microalloyed magnesium alloy described in the first aspect, or the microalloyed magnesium alloy prepared by the method for preparing the microalloyed magnesium alloy described in the second aspect.

[0014] As an example, in automobiles, reducing vehicle weight is beneficial for improving fuel economy and reducing exhaust emissions. Magnesium alloys have the characteristics of low density, high specific strength, and good shock absorption. The magnesium alloy components can be automotive seat frames, dashboards, steering wheels and steering columns, roof covers, gearboxes, door frames, wheel hubs, rear wheel covers, cylinder heads, cylinder blocks, brackets, transmission housings, clutch housings, fuel tank bottoms, dust pans, valve covers, air intake valves and air purifier covers, brackets, piston rings, steering wheel damping shafts, motors, intake manifolds, safety components, etc. (among which, steering wheels, steering shafts, and wheel hubs are the parts that use magnesium alloys the most), but are not limited to these. In electronic products, magnesium alloys are widely used in the manufacture of casings due to their excellent strength, heat dissipation, and electromagnetic shielding properties. These magnesium alloy components can be, but are not limited to, laptop casings, smartphone frames, and tablet casings. In aircraft and spacecraft, weight reduction is crucial for improving performance and efficiency. Magnesium alloys, with their low density, can significantly reduce the weight of aircraft and spacecraft, thereby saving fuel consumption and increasing payload. These magnesium alloy components can be aircraft fuselage frames, engine parts, aviation instruments, etc.; they can also be satellite structural components, supports, etc., but are not limited to these. Magnesium alloys possess excellent biocompatibility and biodegradability, making them a promising candidate for applications in the medical field. The magnesium alloy components may be implants such as orthopedic bone plates and screws, but are not limited to these. In sports equipment, magnesium alloys are characterized by their light weight and high strength. The magnesium alloy components can be golf club heads, bicycle frames, etc., but are not limited to these.

[0015] Fourthly, the present invention also provides a terminal product comprising the magnesium alloy component described in the third aspect.

[0016] As an example, the terminal products may include automobiles, electronic products (such as mobile phones, computers, etc.), airplanes, spacecraft, medical implants, sports equipment, etc., but are not limited to these.

[0017] The technical solution of this invention has the following advantages: 1. The microalloyed magnesium alloy provided by this invention, by strictly limiting the alloy composition to a low content range (Mn: 0.2~0.7%, Zn: 0.2~0.5%, Ce: 0.1~0.3%), avoids the high cost problem caused by the large amount of alloying elements added in traditional high-alloyed magnesium alloys from the source, and fundamentally eliminates the technical defect that the formation of coarse and brittle second phase due to high alloy content can seriously impair plasticity. At the same time, this magnesium alloy has a specific structure in which dynamically recrystallized grains (average grain size 0.5~2μm) and non-dynamically recrystallized regions coexist, and the volume fraction of dynamic recrystallization is controlled at 20%~50%. This unique heterogeneous microstructure enables it to obtain high strength and good plasticity under low alloying conditions, with a yield strength ≥290MPa and an elongation ≥8.5%, successfully overcoming the contradiction of traditional magnesium alloys that are difficult to balance strength and plasticity.

[0018] 2. The short-process preparation method for microalloyed magnesium alloys provided by this invention, by strictly limiting the alloy composition to a low content range and combining it with a specific process of long-term aging (holding time ≥80h), promotes the generation of a large number of fine and dispersed precipitates (such as α-Mn, β-Mn, Mg) in the low alloy composition system. 12 The Ce phase is a key component of magnesium alloys. Larger precipitates act as effective nucleation sites for dynamic recrystallization during subsequent hot extrusion, promoting the dynamic recrystallization of deformed grains. Smaller precipitates pin grain boundaries and dislocations, inhibiting recrystallization and preventing abnormal grain growth. This results in a microstructure (heterogeneous microstructure) where fine dynamically recrystallized grains coexist with elongated, non-dynamically recrystallized grains. The synergistic effect of this specific composition and long-term aging effectively overcomes the inherent contradiction between strength and plasticity in traditional low-alloy magnesium alloys. While significantly reducing raw material and process costs, it successfully achieves a synergistic improvement in the strength and plasticity of magnesium alloys, effectively solving the industrial problem of high cost, complex processes, and the presence of coarse second phases in existing high-alloy magnesium alloys, which hinder the balance between strength and plasticity.

[0019] 3. The short-process preparation method for microalloyed magnesium alloys provided by this invention allows for further short-time annealing (holding time 0-30 min) after prolonged aging and hot extrusion deformation. This short-time annealing step enables precise control of the ratio of dynamic recrystallization zones to non-dynamic recrystallization zones in the formed heterogeneous structure. This allows for further fine-tuning and optimization of the final strength-plasticity matching relationship of the alloy without compromising the material's basic properties. It provides a flexible process control method to meet the specific performance requirements of different application scenarios, further enhancing the practicality and adaptability of this invention. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a graph showing the room temperature mechanical properties of the microalloyed magnesium alloy prepared in Example 1. Figure 2 This is a microstructure diagram of the microalloyed magnesium alloy obtained in Example 1; Figure 3 This is a microstructure diagram of the microalloyed magnesium alloy obtained in Example 2; Figure 4 This is a microstructure diagram of the microalloyed magnesium alloy obtained in Example 3; Figure 5 This is a microstructure diagram of the microalloyed magnesium alloy obtained in Example 4. Detailed Implementation

[0022] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0023] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0024] Example 1 This embodiment provides a short-process preparation method for microalloyed magnesium alloys, and the specific steps are as follows: (1) Based on an alloy composition with a mass percentage of manganese: 0.6%, zinc: 0.4%, cerium: 0.2%, unavoidable impurities totaling 0.03%, and the balance being magnesium, the corresponding pure magnesium, pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were weighed as raw materials. Under the protection of a mixed gas composed of carbon dioxide and sulfur hexafluoride in a volume ratio of 99:1, the pure magnesium was first held at 300℃ for 60 min, and then the temperature was raised to 690℃ to completely melt it, obtaining a magnesium melt. The pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were preheated at 200℃ for 60 min, and then added sequentially to the magnesium melt, and the temperature was raised to 700℃ to completely melt the alloy materials. After stirring and holding the melt for 10 min, argon gas was blown in for refining and removing slag, and then it was allowed to stand for 15 min to obtain a refined magnesium alloy melt. The refined magnesium alloy molten metal is poured into a mold preheated to 300°C using gravity casting, and after cooling, the magnesium alloy ingot is obtained.

[0025] (2) The magnesium alloy ingot obtained in step (1) was aged at 200℃ for 96 hours. Immediately afterwards, it was water-cooled to room temperature. The aged magnesium alloy ingot was preheated at 300℃ for 60 minutes, and then hot-extruded at 300℃ with an extrusion ratio of 28:1 and an extrusion speed of 2.8 mm / s. After hot extrusion, the alloy was cooled to room temperature in air. A microalloyed magnesium alloy was obtained. The yield strength of the obtained microalloyed magnesium alloy was 309 MPa, and the elongation was 9.3%. The room temperature tensile stress-strain curve of the obtained microalloyed magnesium alloy is shown below. Figure 1 As shown, the test was conducted in accordance with GB / T228.1-2021 "Metallic materials, tensile testing—Part 1: Test at room temperature"; the microstructure of the obtained microalloyed magnesium alloy is as follows. Figure 2 As shown, by Figure 2 As can be seen, the microalloyed magnesium alloy exhibits a structure in which fine dynamic recrystallized grains and elongated non-dynamic recrystallized grains coexist. The average grain size of the dynamic recrystallized grains is 1.27 μm, and the volume fraction of the dynamic recrystallized region is 31.7%.

[0026] Example 2 This embodiment provides a short-process preparation method for microalloyed magnesium alloys, and the specific steps are as follows: (1) Based on an alloy composition with a mass percentage of manganese: 0.6%, zinc: 0.4%, cerium: 0.2%, unavoidable impurities totaling 0.03%, and the balance being magnesium, the corresponding pure magnesium, pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were weighed as raw materials. Under the protection of a mixed gas composed of carbon dioxide and sulfur hexafluoride in a volume ratio of 99:1, the pure magnesium was first held at 300℃ for 60 min, and then the temperature was raised to 690℃ to completely melt it, obtaining a magnesium melt. The pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were preheated at 200℃ for 60 min, and then added sequentially to the magnesium melt, and the temperature was raised to 700℃ to completely melt the alloy materials. After stirring and holding the melt for 10 min, argon gas was blown in for refining and removing slag, and then it was allowed to stand for 15 min to obtain a refined magnesium alloy melt. The refined magnesium alloy molten metal is poured into a mold preheated to 300°C using gravity casting, and after cooling, the magnesium alloy ingot is obtained.

[0027] (2) The magnesium alloy ingot obtained in step (1) was aged at 200℃ for 96 hours. Immediately afterwards, it was water-cooled to room temperature. The aged magnesium alloy ingot was preheated at 300℃ for 60 minutes, and then hot-extruded at 300℃ with an extrusion ratio of 28:1 and an extrusion speed of 2.8 mm / s. After hot extrusion, the alloy was cooled to room temperature in air. Finally, the hot-extruded alloy was annealed, specifically by holding at 325℃ for 10 minutes and then water-cooled to room temperature to obtain a microalloyed magnesium alloy. The yield strength of the obtained microalloyed magnesium alloy was 327 MPa, and the elongation was 8.5%. The microstructure of the obtained microalloyed magnesium alloy is as follows: Figure 3 As shown, by Figure 3 As can be seen, the microalloyed magnesium alloy exhibits a structure in which fine dynamic recrystallized grains and elongated non-dynamic recrystallized grains coexist. The average grain size of the dynamic recrystallized grains is 1.43 μm, and the volume fraction of the dynamic recrystallized region is 34.1%.

[0028] The following control group was also established in this embodiment: Control group 1: The holding time of the annealing treatment in step (2) was adjusted to 120 min, while the other parameters remained unchanged. The yield strength of the resulting alloy was 223 MPa and the elongation was 12.5%. At this time, the microalloyed magnesium alloy underwent complete static recrystallization, and the average grain size was 32.28 μm.

[0029] Control group 2: The holding time of the annealing treatment in step (2) was adjusted to 60 min, while the other parameters remained unchanged. The yield strength of the resulting alloy was 184 MPa and the elongation was 11.2%. At this time, the microalloyed magnesium alloy underwent complete static recrystallization, with an average grain size of 24.13 μm.

[0030] Example 3 This embodiment provides a short-process preparation method for microalloyed magnesium alloys, and the specific steps are as follows: (1) Based on an alloy composition with a mass percentage of manganese: 0.6%, zinc: 0.4%, cerium: 0.2%, unavoidable impurities totaling 0.03%, and the balance being magnesium, the corresponding pure magnesium, pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were weighed as raw materials. Under the protection of a mixed gas composed of carbon dioxide and sulfur hexafluoride in a volume ratio of 99:1, the pure magnesium was first held at 300℃ for 60 min, and then the temperature was raised to 690℃ to completely melt it, obtaining a magnesium melt. The pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were preheated at 200℃ for 60 min, and then added sequentially to the magnesium melt, and the temperature was raised to 700℃ to completely melt the alloy materials. After stirring and holding the melt for 10 min, argon gas was blown in for refining and removing slag, and then it was allowed to stand for 15 min to obtain a refined magnesium alloy melt. The refined magnesium alloy molten metal is poured into a mold preheated to 300°C using gravity casting, and after cooling, the magnesium alloy ingot is obtained.

[0031] (2) The magnesium alloy ingot obtained in step (1) was aged at 200℃ for 96 hours. Immediately afterwards, it was water-cooled to room temperature. The aged magnesium alloy ingot was preheated at 300℃ for 60 minutes, and then hot-extruded at 300℃ with an extrusion ratio of 28:1 and an extrusion speed of 2.8 mm / s. After hot extrusion, the alloy was cooled to room temperature in air. Finally, the hot-extruded alloy was annealed, specifically by holding at 325℃ for 20 minutes and then water-cooled to room temperature to obtain a microalloyed magnesium alloy. The yield strength of the obtained microalloyed magnesium alloy was 335 MPa, and the elongation was 10.7%. The microstructure of the obtained microalloyed magnesium alloy is as follows: Figure 4 As shown, by Figure 4 As can be seen, the microalloyed magnesium alloy exhibits a structure in which fine dynamic recrystallized grains and elongated non-dynamic recrystallized grains coexist. The average grain size of the dynamic recrystallized grains is 1.61 μm, and the volume fraction of the dynamic recrystallized region is 38.7%.

[0032] Example 4 This embodiment provides a short-process preparation method for microalloyed magnesium alloys, and the specific steps are as follows: (1) Based on an alloy composition with a mass percentage of manganese: 0.6%, zinc: 0.4%, cerium: 0.2%, unavoidable impurities totaling 0.03%, and the balance being magnesium, the corresponding pure magnesium, pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were weighed as raw materials. Under the protection of a mixed gas composed of carbon dioxide and sulfur hexafluoride in a volume ratio of 99:1, the pure magnesium was first held at 300℃ for 60 min, and then heated to 690℃ to completely melt it, obtaining a magnesium melt. The pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were preheated at 200℃ for 60 min, and then added sequentially to the magnesium melt, and the temperature was raised to 700℃ to completely melt the alloy materials. After stirring and holding the melt for 10 min, argon gas was blown in for refining and removing slag, and then it was allowed to stand for 30 min to obtain a refined magnesium alloy melt. The refined magnesium alloy molten metal is poured into a mold preheated to 300°C using gravity casting, and after cooling, the magnesium alloy ingot is obtained.

[0033] (2) The magnesium alloy ingot obtained in step (1) was aged at 200℃ for 96 hours. Immediately afterwards, it was water-cooled to room temperature. The aged magnesium alloy ingot was preheated at 300℃ for 60 minutes, and then hot-extruded at 300℃ with an extrusion ratio of 28:1 and an extrusion speed of 2.8 mm / s. After hot extrusion, the alloy was cooled to room temperature in air. Finally, the hot-extruded alloy was annealed, specifically by holding at 325℃ for 30 minutes and then water-cooled to room temperature to obtain a microalloyed magnesium alloy. The yield strength of the obtained microalloyed magnesium alloy was 292 MPa, and the elongation was 18%. The microstructure of the obtained microalloyed magnesium alloy is as follows: Figure 5 As shown, by Figure 5 As can be seen, the microalloyed magnesium alloy exhibits a structure in which fine dynamic recrystallized grains and elongated non-dynamic recrystallized grains coexist. The average grain size of the dynamic recrystallized grains is 1.84 μm, and the volume fraction of the dynamic recrystallized region is 47.5%.

[0034] Example 5 This embodiment provides a short-process preparation method for microalloyed magnesium alloys, and the specific steps are as follows: (1) Based on an alloy composition with a mass percentage of manganese: 0.7%, zinc: 0.5%, cerium: 0.3%, unavoidable impurities totaling 0.03%, and the balance being magnesium, the corresponding pure magnesium, pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were weighed as raw materials. Under the protection of a mixed gas composed of carbon dioxide and sulfur hexafluoride in a volume ratio of 99:1, the pure magnesium was first held at 300℃ for 90 min, and then heated to 680℃ to completely melt it, obtaining a magnesium melt. The pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were preheated at 180℃ for 80 min, and then added sequentially to the magnesium melt, and the temperature was raised to 680℃ to completely melt the alloy materials. After stirring and holding the melt for 5 min, argon gas was blown in for refining and removing slag, and then it was allowed to stand for 10 min to obtain a refined magnesium alloy melt. The refined magnesium alloy molten metal is poured into a mold preheated to 320°C using gravity casting, and after cooling, the magnesium alloy ingot is obtained.

[0035] (2) The magnesium alloy ingot obtained in step (1) was aged at 250°C for 80 hours. Immediately afterwards, it was water-cooled to room temperature. The aged magnesium alloy ingot was preheated at 280°C for 90 minutes, and then hot-extruded at 350°C with an extrusion ratio of 40:1 and an extrusion speed of 1 mm / s. After hot extrusion, the alloy was cooled to room temperature in air. Finally, the hot-extruded alloy was annealed, specifically by holding at 250°C for 30 minutes and then water-cooled to room temperature to obtain a microalloyed magnesium alloy. The yield strength of the obtained microalloyed magnesium alloy was 312 MPa, and its elongation was 8.9%. At this point, the microalloyed magnesium alloy exhibited a structure consisting of fine dynamically recrystallized grains and elongated, non-dynamically recrystallized grains. The average grain size of the dynamically recrystallized grains was 0.68 μm, and the volume fraction of the dynamically recrystallized region was 21.5%.

[0036] Comparative Example 1 This comparative example provides a method for preparing AE44 magnesium alloy, the specific steps of which are as follows: (1) Obtaining magnesium alloy ingots: Based on the alloy composition by mass percentage (aluminum: 3.99%, cerium: 4.34%, manganese: 0.36%, zinc: 0.02%, iron: 0.002%, with unavoidable impurities and the balance being magnesium), weigh the corresponding industrial pure magnesium, industrial pure aluminum, industrial pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy for smelting. The smelting process uses conventional flux covering protection. After the masterbatch (magnesium ingot) is completely melted, slag is removed, and zinc ingots and magnesium-manganese master alloy are added. After complete melting, the mixture is stirred, allowed to stand, and then cooled and cast to obtain AE44 magnesium alloy ingots.

[0037] (2) Homogenization and Hot Extrusion Deformation: The alloy ingot obtained in step (1) was subjected to homogenization annealing at 400℃ for 11 hours, followed by machining. The machined ingot was then subjected to hot extrusion deformation at 400℃ with an extrusion ratio of 16:1 to obtain extruded AE44 magnesium alloy rods. The room temperature yield strength of the obtained alloy was 179.1 MPa, the tensile strength was 258 MPa, and the elongation was 10.3%. At this point, the alloy underwent complete static recrystallization, with an average grain size of 14.34 μm.

[0038] Comparative Example 2 This comparative example provides a method for preparing Mg-Gd-Y-Zn-Zr magnesium alloy, and the specific steps are as follows: (1) Obtaining magnesium alloy ingots: Based on the alloy composition by mass percentage, gadolinium (Gd): 4.7%, yttrium (Y): 3.4%, zinc (Zn): 1.2%, zirconium (Zr): 0.5%, with the balance being magnesium and unavoidable impurities, weigh the corresponding high-purity magnesium, high-purity zinc, and Mg. Gd master alloy, Mg Y master alloy, Mg Raw materials such as Zr master alloy are smelted in a vacuum induction melting furnace under argon protection. After the metal is completely melted, it is stirred electromagnetically and then slowly quenched in water to obtain Mg-Gd-Y-Zn-Zr alloy ingots.

[0039] (2) Multi-stage homogenization and hot working: The alloy ingot obtained in step (1) was machined to a suitable size. The machined ingot was then subjected to multi-stage homogenization: first, it was held at 510℃ for 16 hours, and then at 450℃ for 24 hours. After homogenization, the alloy was hot-extruded at 450℃ to obtain an extruded alloy sheet. The extruded alloy sheet was rolled in 6 passes at 450℃ with a total reduction of 52%. Before each pass, it was held at the rolling temperature for 10 minutes to obtain the final alloy sheet. The yield strength of the obtained alloy was 255 MPa and the elongation was 8.3%. At this point, the alloy underwent complete static recrystallization, and the average grain size was 36.5 μm.

[0040] Comparative Example 3 This embodiment provides a short-process preparation method for microalloyed magnesium alloys, and the specific steps are as follows: (1) Based on an alloy composition with a mass percentage of manganese: 0.1%, zinc: 0.1%, cerium: 0.05%, unavoidable impurities totaling 0.03%, and the balance being magnesium, the corresponding pure magnesium, pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were weighed as raw materials. Under the protection of a mixed gas composed of carbon dioxide and sulfur hexafluoride in a volume ratio of 90:10, the pure magnesium was first held at 400℃ for 30 min, and then heated to 720℃ to completely melt it, obtaining a magnesium melt. The pure zinc, magnesium-manganese master alloy, and magnesium-cerium master alloy were preheated at 250℃ for 40 min, and then added sequentially to the magnesium melt, and the temperature was raised to 720℃ to completely melt the alloy materials. After stirring and holding the melt for 20 min, nitrogen was blown in for refining and slag removal to obtain a refined magnesium alloy melt. The refined magnesium alloy molten metal is poured into a mold preheated to 280°C using gravity casting, and after cooling, the magnesium alloy ingot is obtained.

[0041] (2) The magnesium alloy ingot obtained in step (1) was aged at 150°C for 110 hours. Immediately afterwards, it was water-cooled to room temperature. The aged magnesium alloy ingot was preheated at 320°C for 30 minutes, and then hot-extruded at 250°C with an extrusion ratio of 15:1 and an extrusion speed of 10 mm / s. After hot extrusion, the alloy was cooled to room temperature in air. Finally, the hot-extruded alloy was annealed, specifically by holding at 350°C for 5 minutes and then water-cooled to room temperature to obtain a microalloyed magnesium alloy. The yield strength of the obtained microalloyed magnesium alloy was 127 MPa, and its elongation was 5.2%. At this point, the microalloyed magnesium alloy exhibited a structure consisting of fine dynamically recrystallized grains and elongated, non-dynamically recrystallized grains. The average grain size of the dynamically recrystallized grains was 2.98 μm, and the volume fraction of the dynamically recrystallized region was 22.15%.

[0042] Comparative Example 4 This comparative example provides a method for preparing a magnesium alloy, which differs from Example 1 only in that the composition of the magnesium alloy ingot, by mass percentage, is manganese: 0.6%, zinc: 0.4%, cerium: 0.5%, with the balance being magnesium and unavoidable impurities. All other conditions are identical to those in Example 1. Testing revealed that the yield strength of the obtained alloy was 252 MPa, and the elongation was 7.2%. This microalloyed magnesium alloy exhibits a structure consisting of fine dynamically recrystallized grains and elongated, non-dynamically recrystallized grains. The average grain size of the dynamically recrystallized grains is 2.11 μm, and the volume fraction of the dynamically recrystallized region is 28.54%.

[0043] Comparative Example 5 This comparative example provides a method for preparing a magnesium alloy, which differs from Example 1 only in that the composition of the magnesium alloy ingot, by mass percentage, is manganese: 0.05%, zinc: 0.4%, cerium: 0.2%, with the balance being magnesium and unavoidable impurities. All other conditions are identical to those in Example 1. Testing revealed that the yield strength of the obtained alloy was 185 MPa, and the elongation was 8.4%. This microalloyed magnesium alloy exhibits a structure consisting of fine dynamically recrystallized grains and elongated, non-dynamically recrystallized grains. The average grain size of the dynamically recrystallized grains is 6.53 μm, and the volume fraction of the dynamically recrystallized region is 87.12%.

[0044] Comparative Example 6 This comparative example provides a method for preparing a magnesium alloy, which differs from Example 1 only in that aging treatment is not performed; instead, hot extrusion deformation and subsequent annealing are performed directly after obtaining the ingot. All other conditions are identical to those in Example 1. Testing revealed that the yield strength of the obtained alloy was 248 MPa, and the elongation was 5.3%. This microalloyed magnesium alloy exhibits a structure consisting of fine dynamically recrystallized grains and elongated, non-dynamically recrystallized grains. The average grain size of the dynamically recrystallized grains is 8.72 μm, and the volume fraction of the dynamically recrystallized region is 79.65%.

[0045] Comparative Example 7 This comparative example provides a method for preparing a magnesium alloy, which differs from Example 1 only in the order of the process steps. Specifically, after obtaining the magnesium alloy ingot, it is first subjected to hot extrusion deformation, then the extruded alloy is aged (held at 200℃ for 96 hours), and finally annealed (held at 300℃ for 20 minutes). All other conditions are exactly the same as in Example 1. The resulting alloy has a yield strength of 238 MPa and an elongation of 6.2%. At this point, the alloy undergoes complete static recrystallization, with an average grain size of 7.88 μm.

[0046] Comparative Example 8 This comparative example provides a method for preparing a magnesium alloy, which differs from Example 1 only in that the holding time for the aging treatment is 24 hours, while all other conditions are exactly the same as in Example 1. The resulting alloy exhibits a yield strength of 247 MPa and an elongation of 8.5%. At this point, the microalloyed magnesium alloy displays a structure consisting of fine dynamically recrystallized grains and elongated, non-dynamically recrystallized grains. The average grain size of the dynamically recrystallized grains is 6.19 μm, and the volume fraction of the dynamically recrystallized region is 68.43%.

[0047] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A microalloyed magnesium alloy, characterized in that, The microalloyed magnesium alloy consists of the following components by weight percentage: Composition: Manganese: 0.2~0.7%, Zinc: 0.2~0.5%, Cerium: 0.1~0.3%, with the balance being magnesium and unavoidable impurities; the microstructure of the microalloyed magnesium alloy includes a structure in which dynamically recrystallized grains and non-dynamically recrystallized regions coexist; wherein, the average grain size of the dynamically recrystallized grains is 0.5~2μm, and the volume fraction of the dynamically recrystallized region is 20%~50%.

2. The microalloyed magnesium alloy according to claim 1, characterized in that, The microalloyed magnesium alloy is composed of the following components by mass percentage: 0.6~0.7% manganese, 0.4~0.5% zinc, 0.2~0.3% cerium, with the balance being magnesium and unavoidable impurities; optionally, the total content of manganese, zinc and cerium in the microalloyed magnesium alloy is ≤1.5wt.%; and the content of unavoidable impurities is ≤0.05wt.%. And / or, the average grain size of the dynamically recrystallized grains is 1~2μm; And / or, the volume fraction of the dynamically recrystallized region is 30%~50%; And / or, the yield strength of the microalloyed magnesium alloy is ≥290MPa, preferably 290~335MPa; And / or, the elongation of the microalloyed magnesium alloy is ≥8.5%, preferably 8.5~18%.

3. A short-process preparation method for microalloyed magnesium alloy as described in claim 1 or 2, characterized in that, Includes the following steps: Obtain a magnesium alloy ingot; wherein the magnesium alloy ingot is composed of the following components by mass percentage: 0.2~0.7% manganese, 0.2~0.5% zinc, 0.1~0.3% cerium, with the balance being magnesium and unavoidable impurities; Magnesium alloy ingots are subjected to aging treatment and hot extrusion deformation in sequence; wherein the holding time of the aging treatment is ≥80h.

4. The short-process preparation method according to claim 3, characterized in that, After the hot extrusion deformation step, the hot extruded alloy is further subjected to annealing treatment; optionally, the annealing temperature is 250~350℃, preferably 280~320℃; the holding time of the annealing treatment is 0~30min. And / or, the heat preservation time for the aging treatment is 80~110h; And / or, the aging treatment temperature is 150~250℃, preferably 180~220℃; And / or, the temperature of the hot extrusion deformation is 250~350℃, preferably 280~320℃; And / or, the extrusion ratio of the hot extrusion deformation is (15~40):1, preferably (25~30):1; And / or, the extrusion speed of the hot extrusion deformation is 1~10mm / s, preferably 2~5mm / s.

5. The short-process preparation method according to claim 3 or 4, characterized in that, After the aging treatment, a water cooling treatment is also performed; preferably, the water cooling treatment process includes: water cooling to room temperature; And / or, before the hot extrusion deformation, the magnesium alloy ingot that has undergone aging treatment is preheated at 280~320℃ for 30~90min; And / or, after the hot extrusion deformation, the process further includes the step of air cooling the alloy to room temperature.

6. The short-process preparation method according to claim 3 or 4, characterized in that, The magnesium alloy ingot is obtained through a smelting and casting process; optionally, the smelting and casting process includes the following steps: Weigh out the raw materials containing magnesium, zinc, manganese and cerium; The raw materials are smelted under a protective atmosphere to obtain a magnesium alloy melt; The magnesium alloy melt is refined. The refined melt is poured into a mold and cooled to obtain a magnesium alloy ingot.

7. The short-process preparation method according to claim 6, characterized in that, The raw materials are pure magnesium, pure zinc, magnesium-manganese master alloy and magnesium-cerium master alloy; And / or, the protective atmosphere is a mixture of carbon dioxide and sulfur hexafluoride; optionally, the volume ratio of carbon dioxide to sulfur hexafluoride in the mixture of carbon dioxide and sulfur hexafluoride is (90~99):(10~1); And / or, the refining process is to refine and remove slag by blowing in an inert gas; optionally, the inert gas includes nitrogen and / or argon. And / or, the casting includes gravity casting; And / or, the preheating temperature of the mold before casting is 280~320℃.

8. The short-process preparation method according to claim 6, characterized in that, The smelting process includes: first, holding pure magnesium at 300~400℃ for 30~90min, then heating it to 680~720℃ to melt it to obtain magnesium melt, and then adding the remaining raw materials that have been preheated at 180~250℃ for 40~80min; And / or, before the refining process, the melted material is stirred and kept at a constant temperature for 5 to 20 minutes; And / or, after the refining process, the process further includes a step of standing and keeping warm for 10 to 30 minutes.

9. A magnesium alloy component, characterized in that, The magnesium alloy component comprises the microalloyed magnesium alloy as described in claim 1 or 2, or the microalloyed magnesium alloy prepared by the method described in any one of claims 3 to 8.

10. A terminal product, characterized in that, The end product includes the magnesium alloy component as described in claim 9.

Images