Magnesium alloy with high forming and stability, preparation method and application of magnesium alloy in thin-wall rotating part

Abstract

The invention provides a magnesium alloy with high formability and stability, a preparation method and application of the magnesium alloy in a thin-wall rotating member, and the magnesium alloy with high formability and stability comprises the following components in percentage by mass: 0.35-1.3% of Al, 0.2-0.6% of Mn, 0.01-0.7% of Zn, 0.12-0.4% of Ca, 0-0.7% of Ce, 0.01-0.3% of Y, less than or equal to 0.05% of inevitable impurities and the balance of Mg. Wherein the sum of Ca, Ce and Y components is greater than or equal to 0.5% and less than or equal to 1%, and the proportion of Ca / (Ce and Y) components is greater than or equal to 0.1 and less than or equal to 1.5; the preparation method comprises the steps of raw material preparation, smelting and casting, stepped homogenization, quenching, fast extrusion and two-stage heat treatment. The high-formability and high-stability magnesium alloy has a weak basal texture with the texture strength smaller than or equal to 6 mrd, the average grain size smaller than or equal to 25 micrometers, the ignition point larger than or equal to 900 DEG C, and the corrosion rate smaller than or equal to 0.2 mm / year or smaller than or equal to 0.1 mg / cm < 2 > / day. The invention further provides application of the high-forming and stability magnesium alloy in preparation of the thin-wall rotating part, the surface of the thin-wall rotating part is free of cracks, the thin-wall rotating part can be a thin wall or a thick wall, and the wall thickness range is 1-10 mm or gt; the alloy has high flame resistance and corrosion resistance while high strength and plasticity are kept, and the strict service stability requirement for flame resistance and corrosion resistance is met.

Description

Technical Field

[0001] This invention relates to the field of magnesium alloy processing, specifically to high formability and stability magnesium alloys, preparation methods, and applications in thin-walled rotating parts. Background Technology

[0002] Thin-walled rotating components are urgently needed in the development of lightweight, high-performance, and high-reliability key components for seamless applications in aerospace, defense, and automotive fields. Magnesium alloys, as the lightest engineering structural metals with a density only 2 / 3 that of aluminum alloys, possess excellent specific strength, vibration damping, and heat dissipation, making them a preferred material for thin-walled rotating components. However, traditional commercial magnesium alloys exhibit poor stability in humid and high-temperature service environments, suffering from severe corrosion and violent combustion. Furthermore, their close-packed hexagonal crystal structure results in poor plasticity and low formability, making their extrusion, stamping, spinning, and rolling processes difficult to match those of aluminum alloys (e.g., magnesium alloys struggle to achieve extrusion speeds of ≥10 m / min, similar to aluminum alloys). Additionally, commercial AZ- or ZK-based magnesium alloy sheets exhibit a strong basal texture (strength ≥10 mrd), making them prone to cracking during the surface thinning deformation process for thin-walled rotating components. Therefore, traditional magnesium alloys cannot meet the stringent stability requirements of short-process, high-efficiency forming and flame-retardant corrosion resistance for thin-walled rotating components.

[0003] Current methods for improving the strength, plasticity, corrosion resistance, flame retardancy, and formability of magnesium alloys can only address a single problem and cannot achieve a balance between any two or three properties. For example, high-alloy magnesium alloys with a large amount of flame-retardant precious metal elements (alloy content ≥9wt.%) can improve flame resistance, but at the same time, a large number of coarse cathode hard and brittle phases are formed in the matrix, resulting in a significant decrease in the alloy's corrosion resistance and formability. Alternatively, using a large amount of corrosion-resistant precious metal elements (≥4wt.%) in magnesium alloys can improve corrosion resistance, but it reduces flame retardancy and formability, and it is difficult to improve strength and plasticity simultaneously. In addition, during the extrusion deformation process of existing AZ-based or ZK-based commercial magnesium alloys, the low-melting-point Mg-Al or Mg-Zn phases in the magnesium matrix are prone to re-dissolution, leading to grain coarsening, sheet cracking, and surface defects such as overheating, wear, and peeling. It is necessary to reduce the extrusion speed (extrusion speed ≤1m / min) to ensure forming quality. In addition, commercial magnesium alloy extruded sheets are prone to strong basal texture and have extremely poor plasticity along the normal direction of the sheet surface. When the curved surface forming angle is too large during the later finishing process of preparing thin-walled rotary parts such as stamping and spinning (forming angle ≤30°), cracking is likely to occur. Moreover, due to the actual thickness of the extruded sheet, it is difficult to reduce the wall thickness during the forming process (generally the wall thickness ≥10mm). This results in the need for an additional rolling process before forming to obtain thin-walled rotary parts, making it difficult to achieve short-process and efficient forming of magnesium alloy thin-walled rotary parts.

[0004] Therefore, under the premise of ensuring high strength and plasticity, how to achieve short-process manufacturing, avoid cracking during forming, reduce the overall raw material content and the total content of precious metals to save costs, while improving the machinability and service stability of magnesium alloys, and obtaining high strength, high plasticity, high melting point and high corrosion resistance, as well as magnesium alloy thin-walled rotating parts that can be formed in both thin and thick walls are the technical problems that urgently need to be solved. Summary of the Invention

[0005] To solve the above-mentioned technical problems, this invention provides a high-formability and stable magnesium alloy, the alloy composition by mass percentage being Al: 0.35-1.3%, Mn: 0.1-0.6%, Zn: 0.01-0.7%, Ca: 0.12-0.4%, Ce: 0-0.7%, Y: 0.01-0.3%, with unavoidable impurities ≤0.05%, and the remainder being Mg; wherein 0.5% ≤ the sum of Ca + Ce + Y components ≤1%, and 0.1 ≤ Ca / (Ce + Y) composition ratio ≤1.5; its preparation method includes the following steps: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 1-10:90-99; pure Mg ingots are melted at 670-710℃, and then heated to 720-750℃, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 670-720℃, and the mixture is stirred, refined and degassed, and allowed to stand to remove slag. Then, it is cast into magnesium alloy ingots by semi-continuous casting or manual casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment and quenching under argon or nitrogen protection to obtain a homogeneous alloy ingot. The step homogenization treatment is as follows: heat treatment at 300-340℃ for 1-4 hours, heat treatment at 400-440℃ for 2-6 hours, and then heat treatment at 480-530℃ for 0.5-5 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 350-480℃, followed by double-stage heat treatment under argon or nitrogen protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 15-100:1 and an extrusion speed of 2-85 m / min. The double-stage heat treatment involves holding at 450-520℃ for 0.5-4 hours, followed by quenching, and then holding at 170-220℃ for 0.5-4 hours. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength ≤6 mrd, an average grain size ≤25 micrometers, an ignition point ≥900℃, and a corrosion rate ≤0.2 mm / year or ≤0.1 mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day, and maintains high strength and plasticity.

[0006] Furthermore, the alloy composition by mass percentage is: Mn: 0.35-0.5%, Y: 0.05-0.18%, Ce: 0.15-0.5%.

[0007] Further, the step homogenization process described in step (3) involves holding the temperature at 310-330℃ for 2-3 hours, at 410-430℃ for 3-5 hours, and then at 490-520℃ for 2-4 hours.

[0008] Further, the rapid extrusion deformation described in step (4) is as follows: the extrusion ratio is 30-90:1 and the extrusion speed is 65-80m / min; the two-stage heat treatment is as follows: after holding at 480-510℃ for 1-2 hours, the heat is quenched and then held at 180-210℃ for 1-3 hours.

[0009] Furthermore, the rapid extrusion deformation described in step (4) has an extrusion speed of 5-64 m / min.

[0010] Furthermore, the high formability and stability magnesium alloy described in step (4) has a weak basal texture with a texture strength of 3-5 mrd, an average grain size of 3-10 micrometers, an ignition point of 920℃ ≤ 970℃, and a corrosion rate of ≤ 0.1 mm / year or ≤ 0.05 mg / cm² after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0011] This invention also provides the application of high-formability and stable magnesium alloys in the preparation of thin-walled rotating parts. The preparation method mainly includes: stamping or spinning the high-formability and stable magnesium alloy along the normal direction of the extrusion surface at 300-420℃ to obtain a thin-walled rotating part. The stamping process involves: stamping speed 5-50 mm / s, die temperature 230-350℃, blank holder force 1-10 kN, and forming angle ≤90°. The spinning process involves: mandrel temperature 230-350℃, spindle speed 100-600 r / min, feed speed 0.1-1 mm / r, and forming angle ≤80°. The resulting thin-walled rotating part has no surface cracks and can be either thin-walled or thick-walled, with a wall thickness range of 1-10 mm or >10 mm. While maintaining high strength and plasticity, the alloy also possesses high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance.

[0012] Existing magnesium alloys typically require the addition of large amounts of flame-retardant and corrosion-resistant precious metals to improve service stability, with the total content of various alloying elements ≥9 wt.%, of which precious metals account for ≥4 wt.%, resulting in high alloy preparation costs. Furthermore, the addition of large amounts of flame-retardant and precious elements to the magnesium matrix easily forms a large number of coarse eutectic phases, reducing the formability of magnesium alloys. Traditional manufacturing processes can only perform casting, resulting in numerous casting defects, and cannot perform rapid extrusion, stamping, or spinning, hindering the short-process, efficient production of high-quality, defect-free magnesium alloy components. In addition, current... Extruded magnesium alloys (such as commercial AZ31) have a strong basal texture, and their grains tend to coarsen after high-temperature heat treatment, resulting in very poor formability. They are prone to cracking during subsequent spinning / stamping finishing processes, especially for thick plates (wall thickness > 10 mm). Cracks are inevitable during the spinning thinning process, making it impossible to spin-thin thick-walled alloy components to prepare rotating parts (wall thickness ≤ 10 mm). Existing traditional commercial wrought magnesium alloys cannot meet the forming requirements of thin-walled rotating parts while ensuring high strength or plasticity, and it is even more difficult to simultaneously possess excellent corrosion resistance or flame resistance.

[0013] This invention reduces the total alloying elements and precious metal content to lower alloy costs. It employs multi-element interactions, precise proportion adjustments, and synergistic control of processes and parameters to effectively reduce the size and volume fraction of the eutectic phase in the magnesium matrix. This allows for the full resolvation of the eutectic phase, resulting in excellent formability. Simultaneously, it overcomes the technical bottlenecks of Mg-Al and Mg-Zn phases causing cracking in magnesium alloys and Mg-RE phases reducing extrusion speed. This includes the ability to perform both fast and slow extrusion forming, with fast extrusion speeds reaching more than 10 times that of traditional magnesium alloys. It effectively solves the problems of surface overheating, wear, peeling, and decreased mechanical properties caused by poor magnesium alloy formability during high-speed extrusion, as well as the formation of easily resolvable low-to-medium melting point Mg-Al and Mg-Zn phases (this invention avoids the formation of low-to-medium melting point Mg-Al and Mg-Zn phases). The melting point of the Mg-Al and Mg-Zn phases leads to surface defects such as cracks, resulting in a decline in mechanical properties. Simultaneously, this invention reduces heat treatment temperature and time, eliminating the need for prolonged high-temperature treatment, allowing the fine eutectic phases to completely dissolve back into the magnesium matrix. Furthermore, through the synergistic control of multi-element microalloying interactions, effective adjustment of proportions, specific element ratios, and optimization of preparation processes and parameters, the magnesium alloy obtained by this invention not only weakens galvanic corrosion induced by the cathodic phase in the matrix, forms a weak basal texture, and refines grains, resulting in a magnesium alloy with a weak basal texture strength ≤6 mrd and an average grain size ≤25 micrometers, but also forms a dense surface oxide film to hinder combustion, ultimately achieving excellent corrosion resistance (corrosion rate ≤0.2 mm / year or ≤0.1 mg / cm²). 2 The magnesium alloy of this invention exhibits high flame retardancy (ignition point ≥900℃) and high heat resistance ( / day). Through the co-segregation of solute elements at grain boundaries and the pinning effect of high-density, high-melting-point nanoparticles on grain boundaries, the microstructure of the magnesium alloy has thermally stable fine grains and weak texture. It can be used to prepare thin-walled rotating parts by stamping or spinning in the later stage (thinning can be carried out with a wall thickness ≤10mm or >10mm without cracking). It can also ensure that the alloy has high strength and plasticity, as well as high flame retardancy and corrosion resistance, meeting the stringent service stability requirements of flame retardancy and corrosion resistance.

[0014] In summary, compared with existing technologies, this invention achieves lower raw material costs, simplified processes, faster production speed and higher production efficiency through the synergistic control of component interactions, specific element ratios, processes and process parameters. While ensuring the excellent strength and plasticity of the alloy, it avoids forming cracks and can quickly prepare high-formability magnesium alloys suitable for forming thin-walled rotary parts (the initial sheet can be either thick-walled or thin-walled) and with high corrosion resistance and high flame resistance. It can achieve high-speed extrusion process parameters and short-process processing that are far superior to existing technologies, making it suitable for mass industrial production and offering significant advantages such as long service life and high safety. Detailed Implementation Example 1

[0015] Taking a high-formability and stable magnesium alloy with the composition Mg-0.7Al-0.5Mn-0.4Zn-0.4Ce-0.25Ca-0.1Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y is 0.75%, and the Ca / (Ce+Y) composition ratio is 0.5:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 2:98; pure Mg ingots are melted at 680℃, and then heated to 720℃, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 690℃, and after thorough stirring, refining and degassing and settling to remove slag, magnesium alloy ingots are cast by semi-continuous casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under argon protection and quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: heat treatment at 330℃ for 2 hours, heat treatment at 440℃ for 6 hours, and heat treatment at 500℃ for 3 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 480℃, followed by double-stage heat treatment under argon protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 40:1 and an extrusion speed of 35m / min. The double-stage heat treatment involves quenching at 500℃ for 1 hour and then holding at 200℃ for 2 hours. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 5.5mrd, an average grain size of 18 micrometers, an ignition point of 915℃, and a corrosion rate of 0.18mm / year or 0.09mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0016] This highly formable and stable magnesium alloy can be stamped at 420°C along the normal direction of the extrusion surface to produce thin-walled rotating parts. The stamping process involves a stamping speed of 10 mm / s, a die temperature of 350°C, a blank holder force of 5 kN, and a forming angle of 90°. The resulting thin-walled rotating parts have no surface cracks and a wall thickness of 5 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Example 2

[0017] Taking a high-formability and stable magnesium alloy with the composition Mg-0.8Al-0.6Mn-0.7Zn-0.5Ce-0.3Ca-0.05Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y is 0.85%, and the Ca / (Ce+Y) composition ratio is 0.55:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 3:97; pure Mg ingots are melted at 685℃, and then heated to 730℃, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 700℃, and the mixture is thoroughly stirred, refined and degassed, and allowed to stand to remove slag. Then, it is cast into magnesium alloy ingots by semi-continuous casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under argon protection and quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: heat treatment at 320℃ for 1 hour, heat treatment at 440℃ for 3 hours, and heat treatment at 490℃ for 5 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 460°C, followed by double-stage heat treatment under argon protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 45:1 and an extrusion speed of 60 m / min. The double-stage heat treatment involves quenching at 460°C for 4 hours and then holding at 200°C for 2 hours. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 5.6 mrd, an average grain size of 16 micrometers, an ignition point of 942°C, and a corrosion rate of 0.07 mm / year or 0.03 mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0018] This highly formable and stable magnesium alloy can be spun at 420°C along the normal direction of the extrusion surface to produce thin-walled rotary parts. The spinning process involves a mandrel temperature of 350°C, a spindle speed of 600 r / min, a feed rate of 1 mm / r, and a forming angle of 80°. The resulting thin-walled rotary parts have no cracks on their surface and a wall thickness of 2 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Example 3

[0019] Taking a high-formability and stable magnesium alloy with the composition Mg-0.9Al-0.5Mn-0.01Zn-0.05Ce-0.2Ca-0.3Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y is 0.55%, and the Ca / (Ce+Y) composition ratio is 0.57:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 9:91; pure Mg ingots are melted at 675℃, and then heated to 735℃. Pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 700℃, and the mixture is thoroughly stirred, refined, degassed and allowed to stand to remove slag. Then, it is cast into magnesium alloy ingots by hand casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under argon protection and quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: heat treatment at 320℃ for 4 hours, heat treatment at 420℃ for 6 hours, and heat treatment at 480℃ for 4 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 480℃, followed by double-stage heat treatment under argon protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 20:1 and an extrusion speed of 70m / min. The double-stage heat treatment involves quenching at 480℃ for 3 hours and then holding at 190℃ for 2 hours. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 5.9mrd, an average grain size of 24 micrometers, an ignition point of 900℃, and a corrosion rate of 0.17mm / year or 0.08mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0020] This highly formable and stable magnesium alloy can be stamped at 390°C along the normal direction of the extrusion surface to produce thin-walled rotating parts. The stamping process involves a stamping speed of 5 mm / s, a die temperature of 320°C, a blank holder force of 1 kN, and a forming angle of 70°. The resulting thin-walled rotating parts have no surface cracks and a wall thickness of 7 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Example 4

[0021] Taking a high-formability and stable magnesium alloy with the composition Mg-0.4Al-0.1Mn-0.2Zn-0.6Ce-0.35Ca-0.03Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y is 0.98%, and the Ca / (Ce+Y) composition ratio is 0.56:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 4:96; pure Mg ingots are melted at 700℃, and then heated to 750℃, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 720℃, and the mixture is thoroughly stirred, refined and degassed, and allowed to stand to remove slag. Then, it is cast into magnesium alloy ingots by hand casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under nitrogen protection and then quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: holding at 340℃ for 1 hour, holding at 400℃ for 6 hours, and then holding at 530℃ for 0.5 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 350°C, followed by double-stage heat treatment under nitrogen protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 100:1 and an extrusion speed of 2 m / min. The double-stage heat treatment involves quenching at 460°C for 3 hours and then holding at 220°C for 0.5 hours. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 3.6 mrd, an average grain size of 6 micrometers, an ignition point of 963°C, and a corrosion rate of 0.07 mm / year or 0.03 mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0022] This highly formable and stable magnesium alloy can be spun at 390°C along the normal direction of the extrusion surface to produce thin-walled rotary parts. The spinning process involves a mandrel temperature of 320°C, a spindle speed of 450 r / min, a feed rate of 0.6 mm / r, and a forming angle of 50°. The resulting thin-walled rotary parts have no surface cracks and a wall thickness of 4 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Example 5

[0023] Taking a high-formability and stable magnesium alloy with the composition Mg-0.3Al-0.25Mn-0.1Zn-0.4Ca-0.3Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca and Y components is 0.7%, and the Ca / Y composition ratio is 1.33:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 3:97; pure Mg ingots are melted at 670℃, and then heated to 720℃, pure Al, pure Zn, Mg-Mn, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 680℃, and after thorough stirring, refining and degassing and settling to remove slag, magnesium alloy ingots are cast by semi-continuous casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under argon protection and quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: heat treatment at 300℃ for 4 hours, heat treatment at 400℃ for 2 hours, and heat treatment at 520℃ for 1 hour. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 460°C, followed by double-stage heat treatment under argon protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 30:1 and an extrusion speed of 65 m / min. The double-stage heat treatment involves quenching at 520°C for 0.5 hours and then holding at 170°C for 4 hours. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 5.4 mrd, an average grain size of 22 micrometers, an ignition point of 920°C, and a corrosion rate of 0.2 mm / year or 0.1 mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0024] This highly formable and stable magnesium alloy can be stamped at 360°C along the normal direction of the extrusion surface to produce thin-walled rotating parts. The stamping process involves a stamping speed of 30 mm / s, a die temperature of 290°C, a blank holder force of 10 kN, and a forming angle of 45°. The resulting thin-walled rotating parts have no surface cracks and a wall thickness of 8 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Example 6

[0025] Taking a high-formability and stable magnesium alloy with the composition Mg-0.5Al-0.3Mn-0.5Zn-0.5Ce-0.2Ca-0.2Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y components is 0.9%, and the Ca / (Ce+Y) composition ratio is 0.29:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 1:99; pure Mg ingots are melted at 690℃, and then heated to 740℃, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 710℃, and the mixture is stirred, refined and degassed, and allowed to stand to remove slag. Then, it is cast into magnesium alloy ingots by hand casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under nitrogen protection and then quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: heat treatment at 310℃ for 3 hours, heat treatment at 430℃ for 3 hours, and then heat treatment at 490℃ for 4 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 370°C, followed by double-stage heat treatment under nitrogen protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 90:1 and an extrusion speed of 5 m / min. The double-stage heat treatment involves quenching at 490°C for 0.5 hours and then holding at 220°C for 0.5 hours. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 4.3 mrd, an average grain size of 7 micrometers, an ignition point of 950°C, and a corrosion rate of 0.08 mm / year or 0.04 mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0026] This highly formable and stable magnesium alloy can be spun at 360°C along the normal direction of the extrusion surface to produce thin-walled rotary parts. The spinning process involves a mandrel temperature of 290°C, a spindle speed of 350 r / min, a feed rate of 0.5 mm / r, and a forming angle of 70°. The resulting thin-walled rotary parts have no surface cracks and a wall thickness of 6 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Example 7

[0027] Taking a high-formability and stable magnesium alloy with the composition Mg-1.0Al-0.6Mn-0.4Zn-0.2Ce-0.3Ca-0.25Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y is 0.75%, and the Ca / (Ce+Y) composition ratio is 0.67:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 6:94; pure Mg ingots are melted at 680℃, and then heated to 720℃, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 690℃, and after thorough stirring, refining and degassing and settling to remove slag, magnesium alloy ingots are cast by semi-continuous casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under argon protection and quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: heat treatment at 300℃ for 3 hours, heat treatment at 420℃ for 3 hours, and heat treatment at 520℃ for 2 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 420°C, followed by double-stage heat treatment under argon protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 60:1 and an extrusion speed of 40 m / min. The double-stage heat treatment involves quenching at 480°C for 2 hours and then holding at 200°C for 1 hour. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 5 mrd, an average grain size of 13 micrometers, an ignition point of 925°C, and a corrosion rate of 0.06 mm / year or 0.03 mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0028] This highly formable and stable magnesium alloy can be stamped at 330°C along the normal direction of the extrusion surface to produce thin-walled rotating parts. The stamping process involves a stamping speed of 20 mm / s, a die temperature of 260°C, a blank holder force of 3 kN, and a forming angle of 60°. The resulting thin-walled rotating parts have no surface cracks and a wall thickness of 10 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Example 8

[0029] Taking a high-formability and stable magnesium alloy with the composition Mg-0.7Al-0.4Mn-0.3Zn-0.6Ce-0.12Ca-0.2Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y is 0.92%, and the Ca / (Ce+Y) composition ratio is 0.15:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 10:90; pure Mg ingots are melted at 690℃, and then heated to 730℃, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 700℃, and after thorough stirring, refining and degassing and settling to remove slag, magnesium alloy ingots are cast by semi-continuous casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under nitrogen protection and then quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: holding at 340℃ for 3 hours, holding at 410℃ for 3 hours, and then holding at 530℃ for 1 hour. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 440℃, followed by double-stage heat treatment under nitrogen protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 50:1 and an extrusion speed of 30m / min. The double-stage heat treatment involves quenching at 450℃ for 4 hours and then holding at 210℃ for 0.5 hours. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 5.3mrd, an average grain size of 21 micrometers, an ignition point of 957℃, and a corrosion rate of 0.13mm / year or 0.06mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0030] This highly formable and stable magnesium alloy can be spun at 330°C along the normal direction of the extrusion surface to produce thin-walled rotary parts. The spinning process involves a mandrel temperature of 260°C, a spindle speed of 200 r / min, a feed rate of 0.3 mm / r, and a forming angle of 60°. The resulting thin-walled rotary parts have no surface cracks and a wall thickness of 1 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Example 9

[0031] Taking a high-formability and stable magnesium alloy with the composition Mg-0.6Al-0.6Mn-0.6Zn-0.7Ce-0.25Ca-0.01Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y is 0.96%, and the Ca / (Ce+Y) composition ratio is 0.35:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 8:92; pure Mg ingots are melted at 670℃, and then heated to 730℃. Pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 700℃, and the mixture is thoroughly stirred, refined, degassed and allowed to stand to remove slag. Then, it is cast into magnesium alloy ingots by hand casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under nitrogen protection and then quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: heat treatment at 300℃ for 3 hours, heat treatment at 410℃ for 6 hours, and then heat treatment at 480℃ for 5 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 390°C, followed by double-stage heat treatment under nitrogen protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 80:1 and an extrusion speed of 10 m / min. The double-stage heat treatment involves quenching at 470°C for 2 hours and then holding at 180°C for 1 hour. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 4.5 mrd, an average grain size of 8 micrometers, an ignition point of 960°C, and a corrosion rate of 0.08 mm / year or 0.04 mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0032] This highly formable and stable magnesium alloy can be stamped at 300℃ along the normal direction of the extrusion surface to produce thin-walled rotating parts. The stamping process is as follows: stamping speed is 40mm / s, die temperature is 230℃, blank holder force is 8kN, and forming angle is 30°. The thin-walled rotating parts have no cracks on the surface and a wall thickness of 9mm. While maintaining high strength and plasticity, the alloy also has high flame resistance and corrosion resistance, meeting the stringent service stability requirements of flame resistance and corrosion resistance. Example 10

[0033] Taking a high-formability and stable magnesium alloy with the composition Mg-0.5Al-0.2Mn-0.05Zn-0.5Ce-0.15Ca-0.15Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y is 0.8%, and the Ca / (Ce+Y) composition ratio is 0.23:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 4:96; pure Mg ingots are melted at 710℃, and then heated to 750℃. Pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 670℃, and the mixture is stirred, refined, degassed and allowed to stand to remove slag. Then, it is cast into magnesium alloy ingots by semi-continuous casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under argon protection and quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: heat treatment at 330℃ for 2 hours, heat treatment at 430℃ for 4 hours, and heat treatment at 510℃ for 4 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 470℃, followed by double-stage heat treatment under argon protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 15:1 and an extrusion speed of 85m / min. The double-stage heat treatment involves quenching at 480℃ for 1 hour and then holding at 190℃ for 1 hour. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 6mrd, an average grain size of 25 micrometers, an ignition point of 930℃, and a corrosion rate of 0.05mm / year or 0.02mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0034] This highly formable and stable magnesium alloy can be spun at 300°C along the normal direction of the extrusion surface to produce thin-walled rotary parts. The spinning process involves a mandrel temperature of 230°C, a spindle speed of 100 r / min, a feed rate of 0.1 mm / r, and a forming angle of 40°. The resulting thin-walled rotary parts have no surface cracks and a wall thickness of 20 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Example 11

[0035] Taking a high-formability and stable magnesium alloy with the composition Mg-0.35Al-0.5Mn-0.03Zn-0.1Ce-0.25Ca-0.25Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y is 0.6%, and the Ca / (Ce+Y) composition ratio is 0.71:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 5:95; pure Mg ingots are melted at 690℃, and then heated to 730℃. Pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 700℃, and the mixture is thoroughly stirred, refined, degassed and allowed to stand to remove slag. Then, it is cast into magnesium alloy ingots by semi-continuous casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under argon protection and quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: heat treatment at 340℃ for 1 hour, heat treatment at 430℃ for 5 hours, and heat treatment at 510℃ for 3 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 410℃, followed by double-stage heat treatment under argon protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 70:1 and an extrusion speed of 20m / min. The double-stage heat treatment involves quenching at 490℃ for 1 hour and then holding at 210℃ for 1 hour. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 4.5mrd, an average grain size of 9 micrometers, an ignition point of 905℃, and a corrosion rate of 0.12mm / year or 0.06mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0036] This highly formable and stable magnesium alloy can be stamped at 410℃ along the normal direction of the extrusion surface to produce thin-walled rotating parts. The stamping process involves a stamping speed of 50 mm / s, a die temperature of 340℃, a blank holder force of 6 kN, and a forming angle of 80°. The resulting thin-walled rotating parts have no surface cracks and a wall thickness of 15 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Example 12

[0037] Taking a high-formability and stable magnesium alloy with the composition Mg-1.3Al-0.4Mn-0.2Zn-0.4Ce-0.3Ca-0.3Y (wt.%) as an example, the unavoidable impurity content is ≤0.05%, with the remainder being Mg; the sum of Ca+Ce+Y is 1%, and the Ca / (Ce+Y) composition ratio is 0.43:1. Its preparation method is as follows: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 9:91; pure Mg ingots are melted at 690℃, and then heated to 730℃, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 680℃, and after thorough stirring, refining and degassing and settling to remove slag, magnesium alloy ingots are cast by semi-continuous casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment under argon protection and quenched to obtain a homogeneous alloy ingot. The step homogenization treatment is: heat treatment at 340℃ for 2 hours, heat treatment at 440℃ for 4 hours, and heat treatment at 480℃ for 4 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 360°C, followed by double-stage heat treatment under argon protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 40:1 and an extrusion speed of 50 m / min. The double-stage heat treatment involves quenching at 510°C for 0.5 hours and then holding at 200°C for 0.5 hours. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength of 4.7 mrd, an average grain size of 12 micrometers, an ignition point of 970°C, and a corrosion rate of 0.11 mm / year or 0.05 mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day.

[0038] This highly formable and stable magnesium alloy can be spun at 420°C along the normal direction of the extrusion surface to produce thin-walled rotary parts. The spinning process involves a mandrel temperature of 350°C, a spindle speed of 500 r / min, a feed rate of 0.8 mm / r, and a forming angle of 75°. The resulting thin-walled rotary parts have no surface cracks and a wall thickness of 3 mm. While maintaining high strength and plasticity, the alloy also exhibits high flame retardancy and corrosion resistance, meeting the stringent service stability requirements for flame retardancy and corrosion resistance. Comparative Example 1

[0039] Source: Materials, 2022 15(5) 1622, Authors: Guonan Liu et al., Title: “Comparison of Corrosion Performance of Extruded and Forged WE43 Mg Alloy”. The article reports a corrosion-resistant extruded magnesium alloy of Mg-1.55Gd-3.79Y-2.43Nd-0.5Zr (wt.%). The alloy composition is as follows: 1.55wt% Gd, 3.79wt% Y, 2.43wt% Nd, 0.5wt% Zr, with the remainder being Mg. Preparation process: casting, solution treatment (525℃-2h), extrusion (extrusion temperature 400℃, extrusion ratio 40:1, extrusion speed 24mm / min). Corrosion rate of the alloy: 0.6mm / year.

[0040] Compared with the present invention, Comparative Example 1 uses a large amount of expensive rare earth elements (Nd, Gd, Y, accounting for 7.77 wt.%). The total addition content and rare earth content of the alloy in Comparative Example 1 are much higher than the maximum addition amount of the alloy in the present invention. Therefore, the production cost of Comparative Example 1 is much higher than that of the present invention. In addition, the extrusion ratio of the alloy in Comparative Example 1 is small (40:1) and the extrusion speed is slow (24 mm / min). Due to the slow extrusion speed of the alloy in Comparative Example 1, the formability is low. It also does not provide a technical solution that can achieve the thin-walled rotating parts obtained by stamping or spinning along the normal direction of the extrusion surface at temperatures above 300°C as in the present invention. According to existing technology reports, the corrosion rate and corrosion resistance are inversely proportional. That is, the higher the corrosion rate, the worse the corrosion resistance. The comparison results show that the best corrosion resistance of the alloy obtained in Comparative Example 1 (corrosion rate 0.6 mm / year) is significantly weaker than the worst corrosion resistance of the present invention (corrosion rate ≤ 0.2 mm / year). Comparative Example 2

[0041] Source: Metals, 2020 10(11) 1522, Authors: Chenxi Yang et al., Title: “Effect of Microstructure on Corrosion Behavior of WE43 Magnesium Alloy in As Cast and Heat-Treated Conditions”. The article reports a Mg-4.3Y-3.4(Gd, Nd)-0.4Zr (wt.%) wrought corrosion-resistant magnesium alloy. The alloy composition is as follows: 4.3wt% Y, 3.4wt% mixed (Gd, Nd) rare earth elements, 0.4wt% Zr, and the remainder is Mg. Preparation process: casting, rolling at 525℃, and aging heat treatment at 210℃ for 48h. Corrosion performance: corrosion rate 0.88mg / cm2 / day.

[0042] Compared to this invention, the magnesium alloy of Comparative Example 2 contains a high content of rare earth elements (total rare earth element content reaches 7.7 wt.%), belonging to a high rare earth magnesium alloy system, and its raw material cost is much higher than that of this invention. Furthermore, the magnesium alloy of Comparative Example 2 has poor formability, requiring rolling deformation at a high temperature of 525°C, which is far higher than the maximum extrusion deformation temperature of this invention (extrusion deformation at 350-480°C). The alloy of Comparative Example 2, after rolling deformation, does not provide a technical solution that can achieve the thin-walled rotating parts obtained by stamping or spinning along the normal direction of the extrusion surface at temperatures exceeding 300°C as in this invention. However, the result is the lowest corrosion resistance of this invention (≤0.1 mg / cm³). 2 / day) is far superior to the best corrosion resistance of the comparative magnesium alloy (0.88mg / cm). 2 / day).

[0043] In summary, compared with existing technologies, this invention reduces the total amount of alloy or precious metals added, simplifies the process, and employs process parameters such as rapid extrusion that are far higher than those in existing technologies (breaking through the technical bottleneck of adding rare earth elements to reduce alloy extrusion speed). It also effectively solves the problems of cracking of the sheet metal and surface defects such as overheating, wear, and peeling caused by the presence of Mg-Al or Mg-Zn phases. Through the interaction of components, effective control of component ratios, and synergistic control of processes and process parameters, it optimizes the microstructure by weakening cathodic phase corrosion, refining grain size, weakening basal texture, and densifying the oxide film. This achieves co-segregation of solute elements at grain boundaries and pinning of grain boundaries by high-density, high-melting-point nanoparticles. Even during rapid extrusion and large-angle bending deformation, it effectively avoids the occurrence of magnesium alloy cracks and increases the extrusion speed (10 times that of traditional magnesium alloys). The above-mentioned invention enables the subsequent precision machining of thin-walled rotating parts, meaning that without any cracking, it can directly obtain thin-walled or thick-walled parts, or thin-walled parts can be obtained by reducing the thickness of thick-walled materials. While ensuring the high strength and plasticity of the alloy, it simultaneously improves the comprehensive properties of magnesium alloys, such as processability, flame resistance, and corrosion resistance. It has prospects for industrial production and breaks through the technical bottleneck that it is difficult to simultaneously improve the properties of any two or three alloys in existing technologies. In addition, the proportions and process parameters used in each embodiment of the present invention are different, but the material properties obtained are different. This shows that the excellent effect obtained by the present invention is not determined by a certain component, proportion, process, or process parameter, but is achieved through the interaction of components, the synergistic regulation of proportion, process, and process parameters. Moreover, the best technical effect can only be achieved within the scope of the claims.

Claims

1. A high-formability and high-stability magnesium alloy, characterized in that: The alloy composition, by mass percentage, is Al: 0.35-1.3%, Mn: 0.1-0.6%, Zn: 0.01-0.7%, Ca: 0.12-0.4%, Ce: 0-0.7%, Y: 0.01-0.3%, with unavoidable impurities ≤0.05%, and the remainder being Mg; wherein 0.5% ≤ the sum of Ca + Ce + Y ≤1%, and 0.1 ≤ the Ca / (Ce + Y) composition ratio ≤1.5; its preparation method includes the following steps: (1) Raw material preparation: Select and weigh pure Mg, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloy raw materials according to the mass percentages mentioned above; (2) Melting and casting: Under the protection of SF6 and CO2 mixed gas, the volume ratio of SF6 and CO2 is 1-10:90-99; pure Mg ingots are melted at 670-710℃, and then heated to 720-750℃, pure Al, pure Zn, Mg-Mn, Mg-Ce, Mg-Ca and Mg-Y master alloys are added; after heating and melting, the temperature is lowered to 670-720℃, and the mixture is stirred, refined and degassed, and allowed to stand to remove slag. Then, it is cast into magnesium alloy ingots by semi-continuous casting or manual casting. (3) The magnesium alloy ingot obtained in step (2) is subjected to step homogenization treatment and quenching under argon or nitrogen protection to obtain a homogeneous alloy ingot. The step homogenization treatment is as follows: heat treatment at 300-340℃ for 1-4 hours, heat treatment at 400-440℃ for 2-6 hours, and then heat treatment at 480-530℃ for 0.5-5 hours. (4) The homogeneous alloy ingot obtained in step (3) is subjected to rapid extrusion deformation at 350-480℃, followed by double-stage heat treatment under argon or nitrogen protection to obtain a high-formability and stable magnesium alloy. The rapid extrusion deformation has an extrusion ratio of 15-100:1 and an extrusion speed of 2-85 m / min. The double-stage heat treatment involves holding at 450-520℃ for 0.5-4 hours, followed by quenching, and then holding at 170-220℃ for 0.5-4 hours. The high-formability and stable magnesium alloy has a weak basal texture with a texture strength ≤6 mrd, an average grain size ≤25 micrometers, an ignition point ≥900℃, and a corrosion rate ≤0.2 mm / year or ≤0.1 mg / cm after immersion in 3.5% NaCl solution for 7 days. 2 / day, and maintains high strength and plasticity.

2. The high formability and stability magnesium alloy according to claim 1, characterized in that: The alloy composition by mass percentage is: Mn: 0.35-0.5%, Y: 0.05-0.18%, Ce: 0.15-0.5%.

3. The high formability and stability magnesium alloy according to claim 1, characterized in that: Step (3) describes the stepped homogenization process: heat at 310-330℃ for 2-3 hours, heat at 410-430℃ for 3-5 hours, and then heat at 490-520℃ for 2-4 hours.

4. The high formability and stability magnesium alloy according to claim 1, characterized in that: The rapid extrusion deformation described in step (4) is as follows: the extrusion ratio is 30-90:1 and the extrusion speed is 65-80m / min; the two-stage heat treatment is as follows: after holding at 480-510℃ for 1-2 hours, the heat is quenched and then held at 180-210℃ for 1-3 hours.

5. The high formability and stability magnesium alloy according to claim 1, characterized in that: The rapid extrusion deformation described in step (4) has an extrusion speed of 5-64 m / min.

6. The high formability and stability magnesium alloy according to claim 1, characterized in that: The high-formability and stable magnesium alloy described in step (4) has a weak basal texture with a texture strength of 3-5 mrd, an average grain size of 3-10 micrometers, an ignition point of 920℃≤ignition point≤970℃, and a corrosion rate of ≤0.1 mm / year or ≤0.05 mg / cm² after immersion in 3.5% NaCl solution for 7 days. 2 / day.

7. The application of the high formability and stability magnesium alloy according to any one of claims 1-6 in the preparation of thin-walled rotating parts, wherein its preparation method mainly includes: A thin-walled rotary part is obtained by stamping or spinning a high-formability and stable magnesium alloy along the normal direction of the extrusion surface at 300-420℃. The stamping process has the following parameters: stamping speed 5-50mm / s, die temperature 230-350℃, blank holder force 1-10kN, and forming angle ≤90°. The spinning process has the following parameters: mandrel temperature 230-350℃, spindle speed 100-600r / min, feed speed 0.1-1mm / r, and forming angle ≤80°. The thin-walled rotary part has no cracks on its surface and can be made of either thin-walled or thick-walled material with a wall thickness range of 1-10mm or >10mm. While maintaining high strength and plasticity, the alloy also has high flame resistance and corrosion resistance, meeting the stringent service stability requirements for flame resistance and corrosion resistance.