High-strength and high-plasticity rare earth magnesium alloy deformed material and preparation method thereof

Abstract

The invention discloses a high-strength and high-plasticity rare earth magnesium alloy deformed material and a preparation method thereof, and the high-strength and high-plasticity rare earth magnesium alloy deformed material comprises the following components in percentage by mass: 5.0%-6.5% of Gd, 1.5%-2.4% of Y, 1.0%-2.2% of Zn, 0.3%-0.45% of Zr, 5.0%-7.0% of Er and the balance of Mg. The method for preparing the high-strength and high-plasticity magnesium alloy deformation material comprises the steps of alloy smelting, solution treatment, multidirectional free forging and aging treatment, and finally, the yield strength of the high-strength and high-plasticity rare earth magnesium alloy ranges from 398 MPa to 402 MPa, the tensile strength ranges from 441 MPa to 453 MPa, and the ductility ranges from 15.8% to 17.2%. According to the method, part of Gd elements in the Mg-Gd series alloy with the high Gd content are replaced with Er elements, and the elongation of the Mg-Gd series alloy is greatly improved on the basis that the strength of the Mg-Gd series alloy is basically kept unchanged through solid solution strengthening of Er, aging precipitation promotion and c / a value reduction.

Description

Technical Field

[0001] The invention belongs to the technical field of magnesium alloys, and in particular relates to a high-strength and high-plasticity rare earth magnesium alloy deformed material and a preparation method thereof. Background Art

[0002] Magnesium and magnesium alloys are known as the "green and environmentally friendly engineering materials of the 21st century" due to their low density (about 1.74g / cm3, which is 2 / 3 of aluminum and 1 / 4 of iron), high specific strength, abundant reserves, easy recycling and other excellent properties. They have great development prospects in achieving lightweight transportation, thin and miniaturized devices, energy conservation and emission reduction, and green development.

[0003] After sixty years of development, the application field of magnesium alloy is still far less than that of aluminum alloy and steel, and the commercialization process is greatly hindered. The main reason is that magnesium alloy still has some significant defects: 1. The yield strength and tensile strength are low, which cannot meet the demand for ultra-high strength magnesium alloy in high-tech fields; 2. The elongation is low and the plasticity is poor, which is prone to brittle fracture under service conditions. Therefore, the development of ultra-high strength and toughness magnesium alloy is of great significance to expand the application of magnesium alloy. Summary of the invention

[0004] In order to improve the comprehensive mechanical properties of rare earth magnesium alloy, the present invention provides a high-strength and high-plasticity rare earth magnesium alloy deformed material and a preparation method thereof.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] A high-strength and high-plasticity rare earth magnesium alloy deformed material, comprising, by mass percentage, Gd (gadolinium): 5.0%-6.5%, Y (yttrium): 1.5%-2.4%, Zn (zinc): 1.0%-2.2%, Zr (zirconium): 0.3%-0.45%, Er (erbium): 5.0%-7.0%, and the balance is Mg;

[0007] The high-strength and high-plasticity rare earth magnesium alloy has a yield strength of 398MPa-402MPa, a tensile strength of 441MPa-453MPa, and an elongation of 15.8%-17.2%.

[0008] The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of the present invention comprises the following steps:

[0009] S1: melting the raw materials and then casting to obtain a magnesium alloy ingot;

[0010] S2: homogenizing the magnesium alloy ingot obtained in step S1;

[0011] S3: After the homogenization treatment in step S2 is completed, three multi-directional free forgings are performed;

[0012] S4: After the forging process is completed, the obtained forged plate is subjected to aging treatment to finally obtain a high-strength and high-plasticity magnesium alloy deformed material.

[0013] Preferably, the step S1 specifically includes: the raw materials of the high-strength and high-plasticity rare earth magnesium alloy are Mg ingots, Mg-30Gd master alloys, Mg-30Y master alloys, Mg-30Zr master alloys, Mg-30Er master alloys, and Zn ingots, the raw material Mg ingots are melted, the temperature is raised to 700-720°C, and then the Mg-30Gd master alloy, Mg-30Y master alloy, and Zn ingots are added in sequence, and the temperature is kept for 5-15 minutes, and then the furnace temperature is set to 735-745°C, and the temperature is kept for 10-20 minutes, and then the Mg-30Zr master alloy and Mg-30Er master alloy are added, and the temperature is kept for 10-20 minutes for refining and stirring. After the smelting is completed, an alloy liquid is obtained; and the alloy liquid is cast to obtain a magnesium alloy ingot.

[0014] Preferably, the homogenization treatment in step S2 is: keeping the magnesium alloy ingot at 500° C.-520° C. for 18 h-22 h; and then air cooling.

[0015] Preferably, in step S3, the magnesium alloy ingot after homogenization treatment is preheated to 470°C-480°C, and the multi-directional free forging is: forging along the height direction of the magnesium alloy ingot, and then alternating forging along the length and width directions of the magnesium alloy ingot.

[0016] Preferably, the number of forging passes along the height direction of the magnesium alloy ingot is 1-2 passes, and the deformation amount of a single forging pass along the height direction of the magnesium alloy ingot is 40-50%. The number of alternating forging passes along the length and width directions of the magnesium alloy billet is 2-6 passes, and the deformation amount of a single alternating forging pass is 20-30%.

[0017] Preferably, the speed of the three multi-directional free forgings is 10-25 mm / s.

[0018] Preferably, the step S4 specifically comprises: performing aging treatment on the forged plate obtained after three times of multi-directional free forging: placing the forged plate in a muffle furnace at 190-210° C. for 35-45 hours.

[0019] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0020] (1) The atomic radii of Mg and Er are and The atomic size mismatch between the two is small, so Er has a very large solid solubility in the Mg matrix. The maximum solid solubility of Er at the eutectic temperature is 32.7wt%, and the solid solubility at 200℃ is still as high as 20wt%. This shows that Er is solid-dissolved in the Mg matrix in large quantities, which can provide solid solution strengthening on the one hand; on the other hand, since the atomic radius of Er is slightly smaller than that of Gd (0.178nm), Er can reduce the solid solubility of Gd in the magnesium matrix by isotopic substitution, which is bound to reduce the lattice position required for the solid solution of elements such as Gd (gadolinium) and Y, reduce the solid solubility of Gd and Y, and further promote the precipitation of β-phase during the aging process, which compensates for the strength loss due to the reduction of Gd content.

[0021] Furthermore, the addition of Er significantly increases the number density of β' during aging treatment, indicating that Er can promote failure precipitation and enhance the aging hardening response. It is not only because Er occupies the lattice position of elements such as Gd, but more importantly, the co-segregation of Er- and Zn-enriched solutes occurs, participating in the nucleation and growth of β'. The resistance to the initial nucleation of β-type precipitation mainly comes from the interface energy, and this Er- and Zn-enriched solute cluster or ordered structure is highly coherent with the magnesium matrix. When it serves as the nucleation site of β-type precipitation, it can greatly reduce the coherent strain and reduce the interface energy, thereby promoting the nucleation of a large number of β-type precipitation.

[0022] (2) The large amount of Er dissolution in the Mg matrix can reduce the c / a value and the difference in critical shear stress between basal slip and non-basal slip, thereby promoting the simultaneous activation of the multi-slip system during plastic deformation, refining the grains, and thus greatly improving the ductility.

[0023] (3) The present invention adds a multi-directional free forging process during the preparation process. Under severe plastic deformation, the grains of the magnesium alloy are refined, achieving the purpose of fine grain strengthening, and improving the strength and toughness of the magnesium alloy. At the same time, the multi-directional free forging process is adopted, making the present invention better suitable for large-size magnesium alloys with high strength and improved plasticity.

[0024] (4) In the present invention, a large amount of lower-cost Er element is dissolved in the Mg matrix, thereby achieving the purpose of improving strength and toughness through solid solution strengthening, precipitation strengthening and fine grain strengthening, and reducing the content of the precious rare earth element Gd. Only 5.0wt%-6.5wt% needs to be added, which reduces the cost and obtains a magnesium alloy with a yield strength of 398MPa-402MPa, a tensile strength of 441MPa-453MPa and an elongation of 15.8%-17.2%.

[0025] Therefore, the present invention solves the problem of insufficient plasticity of the ultra-high strength Mg-RE alloy by optimizing the alloy composition, and is easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1This is a characteristic diagram of the microstructure of the magnesium alloy obtained in Example 1 of the present invention;

[0027] Figure 2 This is a characteristic diagram of the microstructure of the magnesium alloy obtained in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The present invention replaces part of the Gd element in the Mg-Gd alloy with a high Gd content with the Er element, and through the solid solution strengthening of Er, the promotion of aging precipitation, and the reduction of the c / a value, the Mg-Gd alloy is greatly improved in elongation while maintaining the strength basically unchanged. At the same time, a multi-directional free forging process is adopted in the preparation process, so that the magnesium alloy of the present invention is more suitable for the production of large-size magnesium alloys.

[0029] It should be noted that the temperature field and deformation degree of different regions of large-sized magnesium alloys are different during thermal deformation, resulting in uneven microstructure and performance during thermal deformation. Therefore, the present invention adopts multi-directional free forging, and adopts three multi-directional free forgings to make the magnesium alloy as uniform as possible in terms of deformation degree, temperature field and microstructure and performance during thermal deformation, thereby making the present invention more suitable for the preparation of large-sized magnesium alloys.

[0030] The preparation method of the high-strength and high-plasticity rare earth magnesium alloy deformed material of the present invention is as follows:

[0031] 1. Raw material selection: The raw materials include Mg ingot, Mg-30Gd master alloy, Mg-30Y master alloy, Mg-30Zr master alloy, Zn ingot and Mg-30Er master alloy.

[0032] 2. Melt the raw material Mg ingot, heat it to 710℃, add Mg-30Gd master alloy, Mg-30Y master alloy and Zn ingot in turn, keep warm for 10min, set the furnace temperature to 740℃, continue to keep warm for 15min, add Mg-30Zr master alloy and Mg-30Er master alloy, continue to keep warm for 15min for refining and stirring, and the smelting is completed to obtain alloy liquid; then cast the alloy liquid into magnesium alloy ingot.

[0033] 3. The magnesium alloy ingot is homogenized by keeping it at 500℃-520℃ for 18h-22h, followed by air cooling to complete the homogenization process.

[0034] 4. During the multi-directional free forging treatment, the magnesium alloy ingot after homogenization treatment is preheated to 470°C-480°C, the deformation of a single forging pass along the height direction of the ingot is 40-50%, the number of alternating forging passes is 2-6 passes, the deformation of a single alternating forging pass is 20-30%, and a total of three multi-directional free forgings are performed, and the speed of the three multi-directional free forgings is 10-25 mm / s.

[0035] 5. Perform aging treatment on the forged plate, the process is: place the forged plate in a muffle furnace at 200℃ for 48 hours.

[0036] The following is a further detailed description of a high-strength and high-plasticity rare earth magnesium alloy deformed material and a preparation method thereof proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description.

[0037] Embodiment 1:

[0038] The technical solution of this embodiment is as follows:

[0039] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment includes:

[0040] Gd: 5.0%, Y: 1.5%, Zn: 1%, Zr: 0.3%, Er: 5%, and the balance is Mg.

[0041] (2) The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment includes the following steps:

[0042] 1. The total weight of each batch is 5kg. When batching, adjust the burnout ratio according to the type and content range of the alloy elements. The raw materials used are: pure Mg, Mg-30Gd, Mg-30Y, pure Zn, Mg-30Zr, Mg-30Er master alloy. Bake the batch and mold before smelting. The initial furnace temperature is set to 710℃, pure Mg is placed in the furnace and heated with the furnace, and protective gas (N2+SF6) is passed. When the furnace temperature rises to 710℃, pure Mg begins to melt after about 10min-15min, and the furnace temperature is reduced to 670℃; when the melt temperature rises to 750℃ again, Mg-30Gd, Mg-30Y, and pure Zn are added, and the furnace temperature is set to 750℃ after 10min of heat preservation, and the heat preservation is continued for 15min, and then Mg-30Zr and Mg-30Er intermediate alloys are added, and the heat preservation is continued for 15min, followed by refining and stirring. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg; stirring: left and right 100 times, up and down 60 times, left and right 100 times, up and down 60 times, left and right 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, the melt is left to stand for 45min before casting. If the composition does not meet the standard, feed supplementation will be carried out until the final direct-reading composition is close to the nominal composition.

[0043] 2. The magnesium alloy ingot is placed in a muffle furnace at 500°C for 20 hours; then air-cooled to complete the homogenization process.

[0044] 3. The magnesium alloy ingot after homogenization treatment is subjected to multi-directional free forging treatment. The magnesium alloy ingot after homogenization treatment is preheated to 480°C. The deformation of a single forging pass along the height direction of the ingot is 45%. Then, the number of alternate forging passes along the width and length directions is 4, and the deformation of a single alternating forging pass is 25%. The above-mentioned multi-directional free forging is carried out three times in total, and the speed of the three multi-directional free forgings is 20 mm / s.

[0045] 4. The forged plate after multi-directional free forging is subjected to aging treatment, and the process is as follows: the forged plate is placed in a muffle furnace at 200°C for 48 hours.

[0046] The yield strength of the alloy was measured by a room temperature tensile mechanical properties testing machine, and the tensile strength was 372 MPa, the tensile strength was 441 MPa, and the elongation was 17.2%.

[0047] Embodiment 2:

[0048] The technical solution of this embodiment is as follows:

[0049] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment includes:

[0050] Gd: 6.5.0%, Y: 2.4%, Zn: 2.2%, Zr: 0.45%, Er: 6.5%, and the balance is Mg.

[0051] (2) The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment includes the following steps:

[0052] 1. The total weight of each batch is 5kg. When batching, adjust the burnout ratio according to the type and content range of the alloying elements. The raw materials used are: pure Mg, Mg-30Gd, Mg-30Y, pure Zn, Mg-30Zr, and Mg-30Er master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put pure Mg into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, pure Mg begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd, Mg-30Y, and pure Zn. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr and Mg-30Er master alloy, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, i.e. 0.06 kg. Stirring: left and right 100 times, up and down 60 times, left and right 100 times, up and down 60 times, left and right 100 times. Take a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, the melt is left to stand for 45 minutes before casting. If the composition does not meet the standard, the material is supplemented until the final direct reading composition is close to the nominal composition.

[0053] 2. The magnesium alloy ingot is placed in a muffle furnace at 500°C for 20 hours; then air-cooled to complete the homogenization process.

[0054] 3. The magnesium alloy ingot after homogenization treatment is subjected to multi-directional free forging treatment. The magnesium alloy ingot after homogenization treatment is preheated to 480°C. The deformation of a single forging pass along the height direction of the ingot is 45%. Then, the number of alternate forging passes along the width and length directions is 4, and the deformation of a single alternating forging pass is 25%. The above-mentioned multi-directional free forging is carried out three times in total, and the speed of the three multi-directional free forgings is 20 mm / s.

[0055] 4. The forged plate after multi-directional free forging is subjected to aging treatment, and the process is as follows: the forged plate is placed in a muffle furnace at 200°C for 48 hours.

[0056] The yield strength of the alloy was measured by a room temperature tensile mechanical properties testing machine, and the tensile strength was 385 MPa, the tensile strength was 453 MPa, and the elongation was 15.8%.

[0057] Comparative Example 1:

[0058] The technical scheme of this comparative example is as follows:

[0059] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment includes:

[0060] Gd: 6%, Y: 2%, Zn: 2%, Zr: 0.4%, and the balance is Mg.

[0061] (2) The preparation method of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this comparative example includes the following process:

[0062] 1. The total weight of each batch is 5kg. When batching, adjust the burnout ratio according to the type and content range of the alloying elements. The raw materials used are: pure Mg, Mg-30Gd, Mg-30Y, pure Zn, Mg-30Zr. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put pure Mg into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, pure Mg begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd, Mg-30Y, and pure Zn. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr alloying elements, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, i.e. 0.06 kg. Stirring: left and right 100 times, up and down 60 times, left and right 100 times, up and down 60 times, left and right 100 times. Take a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, the melt is left to stand for 45 minutes before casting. If the composition does not meet the standard, the material is supplemented until the final direct reading composition is close to the nominal composition.

[0063] 2. The magnesium alloy ingot is placed in a muffle furnace at 500°C for 20 hours; then air-cooled to complete the homogenization process.

[0064] 3. The magnesium alloy ingot after homogenization treatment is subjected to multi-directional free forging treatment. The magnesium alloy ingot after homogenization treatment is preheated to 480°C, and the deformation amount of a single forging pass along the height direction of the ingot is 45%. Then, the number of passes of alternating forging along the width and length directions is 4, and the deformation amount of a single alternating forging pass is 25%. The multi-directional free forging is carried out three times in total, and the speed of the three multi-directional free forgings is 20 mm / s.

[0065] 4. The forged plate after multi-directional free forging is subjected to aging treatment, and the process is as follows: the forged plate is placed in a muffle furnace at 200°C for 48 hours.

[0066] The yield strength of the alloy was measured by a room temperature tensile mechanical properties testing machine, and the tensile strength was 305 MPa, the tensile strength was 394 MPa, and the elongation was 8.5%.

[0067] Comparative Example 2:

[0068] The technical scheme of this comparative example is as follows:

[0069] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment includes:

[0070] Gd: 6%, Y: 2%, Zn: 2%, Zr: 0.4%, Er: 3%, and the balance is Mg.

[0071] (2) The preparation method of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this comparative example includes the following process:

[0072] 1. The total weight of each batch is 5kg. When batching, adjust the burnout ratio according to the type and content range of the alloying elements. The raw materials used are: pure Mg, Mg-30Gd, Mg-30Y, pure Zn, Mg-30Zr, and Mg-30Er master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put pure Mg into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, pure Mg begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd, Mg-30Y, and pure Zn. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr and Mg-30Er master alloy, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, i.e. 0.06 kg. Stirring: left and right 100 times, up and down 60 times, left and right 100 times, up and down 60 times, left and right 100 times. Take a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, the melt is left to stand for 45 minutes before casting. If the composition does not meet the standard, the material is supplemented until the final direct reading composition is close to the nominal composition.

[0073] 2. The magnesium alloy ingot is placed in a muffle furnace at 500°C for 20 hours; then air-cooled to complete the homogenization process.

[0074] 3. The magnesium alloy ingot after homogenization treatment is subjected to multi-directional free forging treatment. The magnesium alloy ingot after homogenization treatment is preheated to 480°C. The deformation amount of a single forging pass along the height direction of the ingot is 45%. Then, the number of passes for alternating forging along the width and length directions is 4, and the deformation amount of a single alternating forging pass is 25%. A total of three multi-directional free forgings are performed, and the speed of the three multi-directional free forgings is 20 mm / s.

[0075] 4. The forged plate after multi-directional free forging is subjected to aging treatment, and the process is as follows: the forged plate is placed in a muffle furnace at 200°C for 48 hours.

[0076] The yield strength of the alloy was measured by a room temperature tensile mechanical properties testing machine, and the tensile strength was 347 MPa, the tensile strength was 430 MPa, and the elongation was 12.1%.

[0077] Comparative Example 3

[0078] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment includes:

[0079] Gd: 6%, Y: 2%, Zn: 2%, Zr: 0.4%, Er: 7.5%, and the balance is Mg.

[0080] (2) The preparation method of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this comparative example includes the following process:

[0081] 1. The total weight of each batch is 5kg. When batching, adjust the burnout ratio according to the type and content range of the alloying elements. The raw materials used are: pure Mg, Mg-30Gd, Mg-30Y, pure Zn, Mg-30Zr, and Mg-30Er master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put pure Mg into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, pure Mg begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd, Mg-30Y, and pure Zn. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr and Mg-30Er master alloy, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, i.e. 0.06 kg. Stirring: left and right 100 times, up and down 60 times, left and right 100 times, up and down 60 times, left and right 100 times. Take a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, the melt is left to stand for 45 minutes before casting. If the composition does not meet the standard, the material is supplemented until the final direct reading composition is close to the nominal composition.

[0082] 2. The magnesium alloy ingot is placed in a muffle furnace at 500°C for 20 hours; then air-cooled to complete the homogenization process.

[0083] 3. The magnesium alloy ingot after homogenization treatment is subjected to multi-directional free forging treatment. The magnesium alloy ingot after homogenization treatment is preheated to 480°C. The deformation amount of a single forging pass along the height direction of the ingot is 45%. Then, the number of passes for alternating forging along the width and length directions is 4, and the deformation amount of a single alternating forging pass is 25%. A total of three multi-directional free forgings are performed, and the speed of the three multi-directional free forgings is 20 mm / s.

[0084] 4. The forged plate after multi-directional free forging is subjected to aging treatment, and the process is as follows: the forged plate is placed in a muffle furnace at 200°C for 48 hours.

[0085] The yield strength of the alloy was measured by a room temperature tensile mechanical properties testing machine, and the tensile strength was 330 MPa, the tensile strength was 411 MPa, and the elongation was 14.3%.

[0086] Comparative Example 4

[0087] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment includes:

[0088] Gd: 5%, Y: 1.5%, Zn: 1%, Zr: 0.3%, Er: 3%, and the balance is Mg.

[0089] (2) The preparation method of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this comparative example includes the following process:

[0090] 1. The total weight of each batch is 5kg. When batching, adjust the burnout ratio according to the type and content range of the alloying elements. The raw materials used are: pure Mg, Mg-30Gd, Mg-30Y, pure Zn, Mg-30Zr, and Mg-30Er master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put pure Mg into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, pure Mg begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd, Mg-30Y, and pure Zn. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr and Mg-30Er master alloy, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, i.e. 0.06 kg. Stirring: left and right 100 times, up and down 60 times, left and right 100 times, up and down 60 times, left and right 100 times. Take a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, the melt is left to stand for 45 minutes before casting. If the composition does not meet the standard, the material is supplemented until the final direct reading composition is close to the nominal composition.

[0091] 2. The magnesium alloy ingot is placed in a muffle furnace at 500°C for 20 hours; then air-cooled to complete the homogenization process.

[0092] 3. The magnesium alloy ingot after homogenization treatment is subjected to multi-directional free forging treatment. The magnesium alloy ingot after homogenization treatment is preheated to 480°C. The deformation amount of a single forging pass along the height direction of the ingot is 45%. Then, the number of passes for alternating forging along the width and length directions is 4, and the deformation amount of a single alternating forging pass is 25%. A total of three multi-directional free forgings are performed, and the speed of the three multi-directional free forgings is 20 mm / s.

[0093] 4. The forged plate after multi-directional free forging is subjected to aging treatment, and the process is as follows: the forged plate is placed in a muffle furnace at 200°C for 48 hours.

[0094] The yield strength of the alloy was measured by a room temperature tensile mechanical properties testing machine, and the tensile strength was 316 MPa, the tensile strength was 407 MPa, and the elongation was 15.5%.

[0095] Comparative Example 5

[0096] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment includes:

[0097] Gd: 6.5%, Y: 2.4%, Zn: 2.2%, Zr: 0.45%, Er: 7.5%, and the balance is Mg.

[0098] (2) The preparation method of the high-strength and high-plasticity rare earth magnesium alloy deformed material of this comparative example includes the following process:

[0099] 1. The total weight of each batch is 5kg. When batching, adjust the burnout ratio according to the type and content range of the alloying elements. The raw materials used are: pure Mg, Mg-30Gd, Mg-30Y, pure Zn, Mg-30Zr, and Mg-30Er master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put pure Mg into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, pure Mg begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd, Mg-30Y, and pure Zn. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr and Mg-30Er master alloy, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, i.e. 0.06 kg. Stirring: left and right 100 times, up and down 60 times, left and right 100 times, up and down 60 times, left and right 100 times. Take a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, the melt is left to stand for 45 minutes before casting. If the composition does not meet the standard, the material is supplemented until the final direct reading composition is close to the nominal composition.

[0100] 2. The magnesium alloy ingot is placed in a muffle furnace at 500°C for 20 hours; then air-cooled to complete the homogenization process.

[0101] 3. The magnesium alloy ingot after homogenization treatment is subjected to multi-directional free forging treatment. The magnesium alloy ingot after homogenization treatment is preheated to 480°C. The deformation amount of a single forging pass along the height direction of the ingot is 45%. Then, the number of passes for alternating forging along the width and length directions is 4, and the deformation amount of a single alternating forging pass is 25%. A total of three multi-directional free forgings are performed, and the speed of the three multi-directional free forgings is 20 mm / s.

[0102] 4. The forged plate after multi-directional free forging is subjected to aging treatment, and the process is as follows: the forged plate is placed in a muffle furnace at 200°C for 48 hours.

[0103] The yield strength of the alloy was measured by a room temperature tensile mechanical properties testing machine, and the tensile strength was 322 MPa, the tensile strength was 427 MPa, and the elongation was 11.2%.

[0104] The elemental compositions of the magnesium alloy deformed materials of Examples 1-2 and Comparative Examples 1-5 are shown in Table 1:

[0105]

[0106]

[0107] The tensile mechanical properties of the magnesium alloy deformed materials of Examples 1-2 and Comparative Examples 1-5 are shown in Table 2:

[0108] Yield strength / MPa Tensile strength / MPa Elongation Example 1 372 441 17.2％ Example 2 385 453 15.8％ Comparative Example 1 305 394 8.5％ Comparative Example 2 347 430 12.1％ Comparative Example 3 330 411 14.3％ Comparative Example 4 316 407 15.5％ Comparative Example 5 322 427 11.2

[0109] The components of Examples 1 and 2 are within the design range of the present invention, while no Er element is added in Comparative Example 1, a small amount of Er element is added in Comparative Examples 2 and 4, and an excessive amount of Er element is added in Comparative Examples 3 and 5. By comparing the stress-strain curves in the attached figure, it can be seen that the yield strength, tensile strength and elongation of the magnesium alloy in the comparative example are much lower than those in the examples. Therefore, it can be concluded that the Er element introduced and the designed composition range of the present invention play an important role in improving the mechanical properties of the Mg-Gd-Y-Zn-Zr alloy.

[0110] contrast Figure 1 and Figure 2 It can be seen from the microstructure of the deformed material that the grain structure of Example 1 is significantly smaller than that of Comparative Example 1, which proves that the trace addition of Er greatly promotes grain refinement during free forging deformation and significantly improves the comprehensive mechanical properties of the alloy through grain refinement strengthening.

[0111] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A high-strength and high-plasticity rare earth magnesium alloy deformed material, characterized in that: In terms of mass percentage, it includes Gd: 5.0%-6.5%, Y: 1.5%-2.4%, Zn: 1.0%-2.2%, Zr: 0.3%-0.45%, Er: 5.0%-7.0%, and the balance is Mg; The high-strength and high-plasticity rare earth magnesium alloy has a yield strength of 398MPa-402MPa, a tensile strength of 441MPa-453MPa, and an elongation of 15.8%-17.2%.

2. A method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material as claimed in claim 1, characterized in that: The following steps are involved: S1: melting the raw materials and then casting to obtain a magnesium alloy ingot; S2: homogenizing the magnesium alloy ingot obtained in step S1; S3: After the homogenization treatment in step S2 is completed, three multi-directional free forgings are performed; S4: After the forging process is completed, the obtained forged plate is subjected to aging treatment to finally obtain a high-strength and high-plasticity magnesium alloy deformed material.

3. The method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material according to claim 2, characterized in that: The step S1 specifically comprises: the raw materials of the high-strength and high-plasticity rare earth magnesium alloy are Mg ingots, Mg-30Gd master alloys, Mg-30Y master alloys, Mg-30Zr master alloys, Mg-30Er master alloys, and Zn ingots; the raw material Mg ingots are melted, the temperature is raised to 700-720°C, and then the Mg-30Gd master alloys, Mg-30Y master alloys, and Zn ingots are added in sequence, and the temperature is kept for 5-15 minutes; then the furnace temperature is set to 735-745°C, and the temperature is kept for 10-20 minutes; then the Mg-30Zr master alloy and Mg-30Er master alloy are added, and the temperature is kept for 10-20 minutes for refining and stirring; after the smelting is completed, a molten alloy is obtained; and the molten alloy is cast to obtain a magnesium alloy ingot.

4. The method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material according to claim 2, characterized in that: The homogenization treatment in step S2 is as follows: keeping the magnesium alloy ingot at 500° C.-520° C. for 18 h-22 h; and then air cooling.

5. The method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material according to claim 2, characterized in that: In step S3, the magnesium alloy ingot after homogenization treatment is preheated to 470°C-480°C, and the multi-directional free forging is: forging along the height direction of the magnesium alloy ingot, and then alternately forging along the length and width directions of the magnesium alloy ingot.

6. The method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material according to claim 5, characterized in that: The number of forging passes along the height direction of the magnesium alloy ingot is 1-2 passes, and the deformation of a single forging pass along the height direction of the magnesium alloy ingot is 40-50%. The number of alternating forging passes along the length and width directions of the magnesium alloy billet is 2-6 passes, and the deformation of a single alternating forging pass is 20-30%.

7. The method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material according to claim 5, characterized in that: The speed of three multi-directional free forgings is 10-25 mm / s.

8. The method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material according to claim 5, characterized in that: The step S4 is specifically as follows: the forged plate obtained after three times of multi-directional free forging is subjected to aging treatment: the forged plate is placed in a muffle furnace at 190-210° C. for 35-45 hours.

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