CN113843387B - High-strength heat-resistant magnesium alloy large forging and preparation method thereof - Google Patents

High-strength heat-resistant magnesium alloy large forging and preparation method thereof Download PDF

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CN113843387B
CN113843387B CN202111128440.1A CN202111128440A CN113843387B CN 113843387 B CN113843387 B CN 113843387B CN 202111128440 A CN202111128440 A CN 202111128440A CN 113843387 B CN113843387 B CN 113843387B
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magnesium alloy
forging
temperature
ingot blank
heat
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CN113843387A (en
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万迎春
肖宏超
曾钢
刘楚明
蒋树农
康心锴
陈鑫
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Central South University
Changsha New Material Industry Research Institute Co Ltd
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Central South University
Changsha New Material Industry Research Institute Co Ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21JFORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/06Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
    • B21J5/08Upsetting
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21JFORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/002Hybrid process, e.g. forging following casting
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/06Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon

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  • Chemical & Material Sciences (AREA)
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  • Crystallography & Structural Chemistry (AREA)
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  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Forging (AREA)

Abstract

The invention provides a high-strength heat-resistant magnesium alloy large forging and a preparation method thereof, belonging to the technical field of magnesium alloy deformation processing. The invention adopts a multidirectional forging process combining radial high-speed forging and axial slow-speed upsetting, so that the performance of a forging stock is greatly improved, the problem of cracking of a large-size forging in the forging process is avoided, the anisotropy of the large-size forging is effectively improved, and the mechanical property of the large-size forging is improved. The embodiment results show that the axial tensile strength of the magnesium alloy large forging is more than or equal to 400MPa, the tangential tensile strength is more than 350MPa, the axial yield strength is more than or equal to 300MPa, the tangential yield strength is more than or equal to 240MPa, the axial and tangential elongations are more than or equal to 3.0%, the axial and tangential tensile strength of the high-strength heat-resistant magnesium alloy large forging is more than or equal to 300MPa, the axial and tangential yield strength is more than or equal to 210MPa, and the axial and tangential elongations are more than or equal to 6.0% at the temperature of 200 ℃.

Description

High-strength heat-resistant magnesium alloy large forging and preparation method thereof
Technical Field
The invention relates to the technical field of magnesium alloy deformation processing, in particular to a high-strength heat-resistant magnesium alloy large forging and a preparation method thereof.
Background
The magnesium alloy is the lightest metal structure material in practical application, and has a series of advantages of light specific gravity, high specific strength and specific stiffness, abundant resources and the like. By adding a certain amount of rare earth elements into the magnesium alloy, the magnesium alloy has excellent high-temperature heat resistance and mechanical properties even superior to those of some traditional aluminum alloys. The magnesium alloy part is used for replacing an aluminum alloy part, a good weight reduction effect can be obtained, and particularly, when the size of the part is larger, the weight reduction effect is more remarkable, so that a high-performance large-size deformation part is prepared by developing a proper forming process, the magnesium alloy part can be effectively promoted to replace part of aluminum alloy parts in the fields of automobile industry, aerospace industry and the like, and the magnesium alloy part has a great application prospect.
However, most magnesium alloys have a hexagonal close-packed crystal structure, and an independent slip system which can be started during plastic deformation is lower than that of aluminum alloys, so that the processing and forming properties are poor. Particularly, more inclusions are usually present in the magnesium alloy ingot blank with the ultra-large diameter, the defects of coarse grains, loose structure, surface or core cracks and the like are easy to occur, meanwhile, the large forging has the problems of non-uniform deformation, poor anisotropy and the like, the large forging is easy to crack in the machining process, and even if the large forging is formed by means of reluctant machining, the performance and the uniformity of the performance of the product are not ideal. These pose a serious challenge to the forming and processing of high-performance large-size magnesium alloy deformed pieces.
In the prior art, CN108467982A, an aging heat treatment process for Mg-Gd-Y-Zr nano magnesium alloy, discloses a scheme for preparing magnesium alloy by using a rotary swaging deformation process, realizes alloy aging strengthening by means of rotary swaging and multistage aging heat treatment, and improves the room-temperature tensile strength and yield strength of the magnesium alloy, but the process can only be applied to small-sized bars or tubes, and the problems of magnesium alloy cracking and the like still occur when large-sized magnesium alloy members are prepared, so that the process cannot be used for preparing large-sized members. Therefore, a preparation method of a large-size magnesium alloy forging with excellent mechanical property needs to be provided.
Disclosure of Invention
The invention aims to provide a high-strength heat-resistant magnesium alloy large forging and a preparation method thereof.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a large high-strength heat-resistant magnesium alloy forging, which comprises the following steps:
(1) homogenizing a magnesium alloy ingot to obtain a pretreated magnesium alloy;
(2) preparing the pretreated magnesium alloy obtained in the step (1) into a cylindrical ingot blank;
(3) Preserving the heat of the cylindrical ingot blank obtained in the step (2), and then performing radial forging to obtain a forged ingot blank;
(4) carrying out temperature returning treatment on the forging ingot blank obtained in the step (3), and then carrying out axial upsetting to obtain an upset ingot blank;
(5) repeating the operation of the step (3) and the operation of the step (4) for 1-2 times to obtain a forged magnesium alloy;
(6) carrying out heat treatment on the forged magnesium alloy obtained in the step (5) to obtain a high-strength heat-resistant magnesium alloy large forging;
the parameters of the radial forging in the step (3) and the step (5) are independently: the frequency is 20-200 times/min, and the strain rate is 10-200 s-1(ii) a The deformation amount of each radial forging is 1-5%;
the parameters of the axial upsetting in the step (4) and the step (5) are independently as follows: the reduction speed is 6-10 mm/s, and the pass deformation is 20-40%;
and (5) when the step (3) is repeated, the heat preservation temperature is 5-20 ℃ lower than that of the last time, and the heat preservation time is 0.5-2 h.
Preferably, the magnesium alloy ingot in the step (1) comprises the following components in percentage by mass: gd: 7-13%, Y: 2.5-6%, Zr: 0.35-0.8% and the balance of Mg.
Preferably, the temperature of the homogenization treatment in the step (1) is 490-540 ℃, and the time of the homogenization treatment is 20-25 h.
Preferably, the diameter of the cylindrical ingot blank in the step (2) is more than or equal to 900mm, and the height of the cylindrical ingot blank is more than or equal to 200 mm.
Preferably, the temperature for heat preservation in the step (3) is 460-510 ℃, and the time for heat preservation is 12-16 h.
Preferably, the temperature for heat preservation in the step (3) is 470-500 ℃, and the time for heat preservation is 13-15 h.
Preferably, the temperature of the temperature-returning treatment in the step (4) and the step (5) is 380-410 ℃, and the time of the temperature-returning treatment is 1-2 h.
Preferably, the height of the upset ingot blank in the step (4) is the same as the height of the cylindrical ingot blank in the step (2).
Preferably, the temperature of the heat treatment in the step (6) is 350-450 ℃, and the time of the heat treatment is 30-120 min.
The invention provides a high-strength heat-resistant magnesium alloy large forging prepared by the preparation method in the technical scheme.
The invention provides a preparation method of a large high-strength heat-resistant magnesium alloy forging, which comprises the following steps: (1) homogenizing a magnesium alloy ingot to obtain a pretreated magnesium alloy; (2) preparing the pretreated magnesium alloy obtained in the step (1) into a cylindrical ingot blank; (3) preserving the heat of the cylindrical ingot blank obtained in the step (2), and then performing radial forging to obtain a forged ingot blank; (4) carrying out temperature return treatment on the forged ingot blank obtained in the step (3), and then carrying out axial upsetting to obtain an upset ingot blank; (5) repeating the operation of the step (3) and the operation of the step (4) for 1-2 times to obtain a forged magnesium alloy; (6) carrying out heat treatment on the forged magnesium alloy obtained in the step (5) to obtain a high-strength heat-resistant magnesium alloy large forging; the parameters of radial forging in the step (3) and the step (5) are independently: the frequency is 20-200 times/min, and the strain rate is 10-200 s -1(ii) a The deformation of each radial forging is 1-5%; the parameters of the axial upsetting in the step (4) and the step (5) are independently as follows: the reduction speed is 6-10 mm/s, and the pass deformation is 20-40%; and (5) when the step (3) is repeated, the heat preservation temperature is 5-20 ℃ lower than that of the last time, and the heat preservation time is 0.5-2 h. The invention adopts a multidirectional forging process combining radial high-speed forging and axial low-speed upsetting, so that the performance of a forging stock is greatly improved, the problem of cracking of a large-size forging piece in the forging process is avoided, the anisotropy of the large-size forging piece is effectively improved, and the mechanical property of the large-size forging piece is improved. The embodiment results show that the diameter of the high-strength heat-resistant magnesium alloy large forging provided by the invention is more than or equal to 900mm, the height of the high-strength heat-resistant magnesium alloy large forging is more than or equal to 200mm, the axial tensile strength under the room temperature condition is more than or equal to 400MPa, and the tangential tensile strength is more than 350MPa, the axial yield strength is more than or equal to 300MPa, the tangential yield strength is more than or equal to 240MPa, the axial and tangential elongations are more than or equal to 3.0 percent, the axial and tangential tensile strength of the high-strength heat-resistant magnesium alloy large forging at the temperature of 200 ℃ is more than or equal to 300MPa, the axial and tangential yield strength is more than or equal to 210MPa, and the axial and tangential elongations are more than or equal to 6.0 percent.
Detailed Description
The invention provides a preparation method of a large high-strength heat-resistant magnesium alloy forging, which comprises the following steps:
(1) homogenizing a magnesium alloy ingot to obtain a pretreated magnesium alloy;
(2) preparing the pretreated magnesium alloy obtained in the step (1) into a cylindrical ingot blank;
(3) preserving the heat of the cylindrical ingot blank obtained in the step (2), and then performing radial forging to obtain a forged ingot blank;
(4) carrying out temperature returning treatment on the forging ingot blank obtained in the step (3), and then carrying out axial upsetting to obtain an upset ingot blank;
(5) repeating the operation of the step (3) and the operation of the step (4) for 1-2 times to obtain a forged magnesium alloy;
(6) carrying out heat treatment on the forged magnesium alloy obtained in the step (5) to obtain a high-strength heat-resistant magnesium alloy large forging;
the parameters of radial forging in the step (3) and the step (5) are independently: the frequency is 20-200 times/min, and the strain rate is 10-200 s-1(ii) a The deformation amount of each radial forging is 1-5%;
the parameters of the axial upsetting in the step (4) and the step (5) are independently as follows: the reduction speed is 6-10 mm/s, and the pass deformation is 20-40%;
and (5) when the step (3) is repeated, the heat preservation temperature is 5-20 ℃ lower than that of the last time, and the heat preservation time is 0.5-2 h.
The method carries out homogenization treatment on the magnesium alloy ingot to obtain the pretreated magnesium alloy.
In the invention, the magnesium alloy ingot preferably comprises the following components in percentage by mass: gd: 7-13%, Y: 2.5-6%, Zr: 0.35-0.8% and the balance of Mg, more preferably comprising: gd: 8-12%, Y: 3-5%, Zr: 0.4-0.6% and the balance of Mg. The magnesium alloy ingot adopting the components has excellent high-temperature heat resistance and mechanical property.
In the invention, the magnesium alloy ingot is preferably prepared by adopting a semi-continuous electromagnetic casting method. The invention has no special limitation on the specific operation and process parameters of the semi-continuous electromagnetic casting method, and the semi-continuous electromagnetic casting method known to those skilled in the art can be adopted.
In the invention, the temperature of the homogenization treatment is preferably 490-540 ℃, more preferably 500-530 ℃, and further preferably 510-520 ℃; the time for the homogenization treatment is preferably 20 to 25 hours, more preferably 21 to 24 hours, and further preferably 22 to 23 hours. The invention can fully diffuse the chemical components in the magnesium alloy ingot and improve the metallurgical quality of the magnesium alloy ingot by carrying out homogenization treatment on the magnesium alloy ingot.
After the pretreated magnesium alloy is obtained, the invention makes the pretreated magnesium alloy into a cylindrical ingot blank. In the present invention, the diameter of the cylindrical ingot is preferably not less than 900mm, more preferably not less than 1000mm, and the height of the cylindrical ingot is preferably not less than 200mm, more preferably not less than 250 mm.
In the present invention, the preparation steps of the cylindrical ingot blank are preferably: and (4) sequentially carrying out leather turning, flaw detection and sawing machine blanking on the pretreated magnesium alloy to obtain a cylindrical ingot blank. The specific operations of the wagon, the flaw detection and the sawing machine blanking are not particularly limited and can be determined according to the technical common knowledge of the skilled in the art.
After the cylindrical ingot blank is manufactured, the cylindrical ingot blank is subjected to heat preservation and then radial forging to obtain a forged ingot blank.
In the invention, the temperature of the heat preservation is preferably 460-510 ℃, more preferably 470-500 ℃, and further preferably 480-490 ℃; the heat preservation time is preferably 12-16 h, more preferably 13-15 h, and further preferably 14 h. According to the invention, the cylindrical ingot blank is subjected to heat preservation treatment, so that the plasticity of the cylindrical ingot blank can be improved, and the problems of cracking and the like in the forging process are prevented.
In the invention, the frequency of the radial forging is 20-200 times/min, preferably 50-150 times/min, and further preferably 80-120 times/min; the strain rate of the radial forging is 10-200 s -1Preferably 50 to 150s-1More preferably 80 to 120s-1(ii) a The deformation amount of each radial forging is 1-5%, preferably 2-4%, and more preferably 3%. The number of times of forging in each pass in each radial forging is not particularly limited, and may be determined according to the technical knowledge of a person skilled in the art. The specific operation of the radial forging is not particularly limited, and the cylindrical ingot blank can be uniformly forged.
According to the invention, the problem that the large-size forge piece is cracked in the forging process can be avoided through high-speed forging with small-amplitude deformation, the anisotropy of the large-size forge piece is effectively improved, and the mechanical property of the large-size forge piece is improved.
After a forging ingot blank is obtained, the invention carries out temperature return treatment on the forging ingot blank, and then carries out axial upsetting to obtain an upset ingot blank.
In the invention, the temperature of the tempering treatment is preferably 380-410 ℃, and more preferably 390-400 ℃; the time of the tempering treatment is preferably 1-2 h, and more preferably 1.5 h. According to the invention, the temperature of the forged cast ingot can be adjusted to a range suitable for upsetting by carrying out temperature returning treatment on the forged cast ingot, and meanwhile, the temperature inside and outside the cast ingot is consistent.
In the invention, the reduction speed of the axial upsetting is 6-10 mm/s, preferably 7-9 mm/s, and more preferably 8 mm/s; the pass deformation of the axial upsetting is 20-40%, and the preferred pass deformation is 25-35%. The invention can further improve the performance of the forging by limiting the upsetting parameter in the range.
In the present invention, the height of the upset ingot blank is preferably the same as the height of the cylindrical ingot blank. The invention is convenient for subsequent repeated forging and upsetting by upsetting the height of the ingot blank to the original height.
In the present invention, the radial upsetting is preferably performed by using a hammer forging machine, and the axial upsetting is preferably performed by using a hydraulic machine. The present invention is not limited to the specific type of the hammer forging machine and the hydraulic machine, and commercially available products known to those skilled in the art may be used.
After the upsetting ingot blank is obtained, the radial forging and axial upsetting process is repeated for 1-2 times to obtain the forged magnesium alloy. By repeating radial forging and axial upsetting, the invention can greatly improve the performance of the forging stock and improve the mechanical property of large-size forgings.
In the invention, when the radial forging is repeatedly carried out, the heat preservation temperature is preferably 5-20 ℃ lower than the heat preservation temperature before the last radial forging, more preferably 8-15 ℃, and further preferably 10 ℃; the heat preservation time is preferably 0.5-2 hours, and more preferably 1-1.5 hours. The forging method can improve the forging efficiency by adjusting the temperature and time of heat preservation, and is beneficial to further improving the performance of the forging piece.
After the forged magnesium alloy is obtained, the invention carries out heat treatment on the forged magnesium alloy to obtain the high-strength heat-resistant magnesium alloy large-scale forging. In the present invention, the temperature of the treatment is preferably 350 ℃ to 450 ℃, more preferably 400 ℃; the time of the heat treatment is preferably 30 to 120min, more preferably 50 to 100min, and further preferably 70 to 80 min. The strength and toughness of the forged magnesium alloy can be improved by carrying out heat treatment on the forged magnesium alloy.
The preparation method is simple, does not need new equipment, saves the production cost, is beneficial to industrial mass production, and simultaneously improves the quality of large-size forgings.
The invention provides a high-strength heat-resistant magnesium alloy large forging prepared by the preparation method in the technical scheme. The high-strength heat-resistant magnesium alloy large forging provided by the invention has excellent strength and toughness, and is not easy to crack in the subsequent use process.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A preparation method of a high-strength heat-resistant magnesium alloy large forging comprises the following steps:
(1) preparing a magnesium alloy ingot by adopting a semi-continuous electromagnetic casting method, homogenizing the magnesium alloy ingot, and cooling the magnesium alloy ingot to room temperature along with a furnace to obtain a pretreated magnesium alloy; the magnesium alloy ingot comprises the following components in percentage by mass: 8.1% Gd, Y: 3.0%, Zr: 0.4% and the balance of Mg and non-removable impurity elements; the temperature of the homogenization treatment is 520 ℃, and the time of the homogenization treatment is 20 h;
(2) sequentially carrying out turning, flaw detection and sawing machine blanking on the pretreated magnesium alloy obtained in the step (1) to obtain a cylindrical ingot blank with the diameter of 900mm and the height of 200 mm;
(3) preserving the heat of the cylindrical ingot blank obtained in the step (2) for 15 hours at the temperature of 480 ℃, and then performing radial forging by using a hammer forging machine to obtain a forged ingot blank; the frequency of the radial forging is 50 times/min; the deformation of each radial forging is 2%; the total deformation of each forging in the radial forging process is 8 percent; radial forging is carried out for 360 degrees along the radial direction;
(4) preserving the temperature of the forged ingot blank obtained in the step (3) at 390 ℃ for 1h for temperature returning treatment, and then performing axial upsetting by using a hydraulic machine to obtain an upset ingot blank; the reduction speed of the axial upsetting is 8mm/s, and the pass deformation of the axial upsetting is 20%; the height of the upset ingot blank is the same as that of the cylindrical ingot blank in the step (2);
(5) Preserving the temperature of the upset ingot blank obtained in the step (4) at 470 ℃ for 1h, then performing radial forging to obtain a forged ingot blank, continuously preserving the temperature of the forged ingot blank at 390 ℃ for 1h, performing temperature returning treatment, performing axial upsetting, and finally performing air cooling to room temperature to obtain an upset ingot blank; the frequency of the radial forging is 50 times/min; the deformation amount of each radial forging is independently 2%, and the total deformation amount is 12%; the reduction speed of the axial upsetting is 6mm/s, and the pass deformation of the axial upsetting is 20%; the height of the upset ingot blank is the same as that of the cylindrical ingot blank in the step (2);
(6) and (4) carrying out heat treatment on the forged magnesium alloy obtained in the step (5), wherein the heat treatment temperature is 350 ℃, the heat treatment time is 90min, and then carrying out air cooling to room temperature to obtain the high-strength heat-resistant magnesium alloy large forging.
Example 2
A preparation method of a high-strength heat-resistant magnesium alloy large forging comprises the following steps:
(1) preparing a magnesium alloy ingot by adopting a semi-continuous electromagnetic casting method, homogenizing the magnesium alloy ingot, and cooling the magnesium alloy ingot to room temperature along with a furnace to obtain a pretreated magnesium alloy; the magnesium alloy ingot comprises the following components in percentage by mass: 8.7% Gd, Y: 2.6%, Zr: 0.5% and the balance of Mg and non-removable impurity elements; the temperature of the homogenization treatment is 510 ℃, and the time of the homogenization treatment is 24 h;
(2) Turning the pretreated magnesium alloy obtained in the step (1), detecting a flaw and blanking by a sawing machine in sequence to obtain a cylindrical ingot blank with the diameter of 900mm and the height of 220 mm;
(3) preserving the heat of the cylindrical ingot blank obtained in the step (2) at 490 ℃ for 14h, and then performing radial forging by using a hammer forging machine to obtain a forged ingot blank; the frequency of the radial forging is 60 times/min; the deformation of each radial forging is 3%; the total deformation of each forging pass is 9% during radial forging; radial forging is carried out for 360 degrees along the radial direction;
(4) preserving the temperature of the forging ingot blank obtained in the step (3) at 400 ℃ for 1h for carrying out temperature returning treatment, and then carrying out axial upsetting by using a hydraulic machine to obtain an upset ingot blank; the reduction speed of the axial upsetting is 9mm/s, and the pass deformation of the axial upsetting is 25%; the height of the upset ingot blank is the same as that of the cylindrical ingot blank in the step (2);
(5) preserving the temperature of the upset ingot blank obtained in the step (4) at 480 ℃ for 0.5h, then performing radial forging to obtain a forged ingot blank, continuing preserving the temperature of the forged ingot blank at 395 ℃ for 1.5h, performing temperature return treatment, then performing axial upsetting, and finally performing air cooling to room temperature to obtain an upset ingot blank; the frequency of the radial forging is 60 times/min; the deformation amount of each radial forging is independently 2%, and the total deformation amount is 10%; the reduction speed of the axial upsetting is 7mm/s, and the pass deformation of the axial upsetting is 20%; the height of the upset ingot blank is the same as that of the cylindrical ingot blank in the step (2);
(6) And (4) carrying out heat treatment on the forged magnesium alloy obtained in the step (5), wherein the heat treatment temperature is 370 ℃, the heat treatment time is 70min, and then carrying out air cooling to room temperature to obtain the high-strength heat-resistant magnesium alloy large forging.
Example 3
A preparation method of a high-strength heat-resistant magnesium alloy large forging comprises the following steps:
(1) preparing a magnesium alloy ingot by adopting a semi-continuous electromagnetic casting method, homogenizing the magnesium alloy ingot, and cooling the magnesium alloy ingot to room temperature along with a furnace to obtain a pretreated magnesium alloy; the magnesium alloy ingot comprises the following components in percentage by mass: 9.1% Gd, Y: 2.2%, Zr: 0.6 percent, and the balance of Mg and irremovable impurity elements; the homogenization treatment temperature is 530 ℃, and the homogenization treatment time is 25 h;
(2) sequentially carrying out turning, flaw detection and sawing machine blanking on the pretreated magnesium alloy obtained in the step (1) to obtain a cylindrical ingot blank with the diameter of 900mm and the height of 250 mm;
(3) preserving the heat of the cylindrical ingot blank obtained in the step (2) at 490 ℃ for 15h, and then performing radial forging by using a hammer forging machine to obtain a forged ingot blank; the frequency of the radial forging is 50 times/min; the deformation of each radial forging is 3 percent; the total deformation of each forging pass in the radial forging is 18 percent; radial forging is carried out for 360 degrees along the radial direction;
(4) Preserving the temperature of the forging ingot blank obtained in the step (3) at 400 ℃ for 1.5h for carrying out temperature returning treatment, and then carrying out axial upsetting by using a hydraulic machine to obtain an upset ingot blank; the reduction speed of the axial upsetting is 6mm/s, and the pass deformation of the axial upsetting is 25%; the height of the upset ingot blank is the same as that of the cylindrical ingot blank in the step (2);
(5) preserving the temperature of the upset ingot blank obtained in the step (4) at 475 ℃ for 1h, then performing radial forging to obtain a forged ingot blank, continuing preserving the temperature of the forged ingot blank at 400 ℃ for 1h, performing temperature returning treatment, then performing axial upsetting, and finally performing air cooling to room temperature to obtain an upset ingot blank; the frequency of the radial forging is 50 times/min; the deformation amount of each radial forging is independently 2%, and the total deformation amount is 14%; the reduction speed of the axial upsetting is 6mm/s, and the pass deformation of the axial upsetting is 20%; the height of the upset ingot blank is the same as that of the cylindrical ingot blank in the step (2);
(6) and (4) carrying out heat treatment on the forged magnesium alloy obtained in the step (5), wherein the heat treatment temperature is 350 ℃, the heat treatment time is 90min, and then air-cooling to room temperature to obtain the high-strength heat-resistant magnesium alloy large forging.
Comparative example 1
A preparation method of a large magnesium alloy forging comprises the following steps:
(1) preparing a magnesium alloy ingot by adopting a semi-continuous electromagnetic casting method, homogenizing the magnesium alloy ingot, and cooling the magnesium alloy ingot to room temperature along with a furnace to obtain a pretreated magnesium alloy; the magnesium alloy ingot comprises the following components in percentage by mass: gd: 8.7%, Y: 2.6%, Zr: 0.5% and the balance of Mg and non-removable impurity elements; the temperature of the homogenization treatment is 510 ℃, and the time of the homogenization treatment is 24 h;
(2) sequentially carrying out turning, flaw detection and sawing machine blanking on the pretreated magnesium alloy obtained in the step (1) to obtain a cylindrical ingot blank with the diameter of 900mm and the height of 220 mm;
(3) preserving the heat of the cylindrical ingot blank obtained in the step (2) for 14 hours at 490 ℃, then performing unidirectional forging by using a hammer forging machine, and finally performing air cooling to room temperature to obtain a forged magnesium alloy; the frequency of the unidirectional forging is 60 times/minute, the deformation of each forging is 2 percent, and the accumulated deformation is 16 percent;
(4) and (4) carrying out heat treatment on the forged magnesium alloy obtained in the step (3), wherein the heat treatment temperature is 370 ℃, the heat treatment time is 70min, and then air-cooling to room temperature to obtain the magnesium alloy large forging.
Comparative example 2
A preparation method of a large magnesium alloy forging comprises the following steps:
(1) preparing a magnesium alloy ingot by adopting a semi-continuous electromagnetic casting method, homogenizing the magnesium alloy ingot, and cooling the magnesium alloy ingot to room temperature along with a furnace to obtain a pretreated magnesium alloy; the magnesium alloy ingot comprises the following components in percentage by mass: gd: 9.1%, Y: 2.2%, Zr: 0.6% and the balance of Mg and non-removable impurity elements; the temperature of the homogenization treatment is 530 ℃, and the time of the homogenization treatment is 25 h;
(2) sequentially carrying out leather turning, flaw detection and sawing machine blanking on the pretreated magnesium alloy obtained in the step (1) to obtain a square ingot blank with the length of 250mm, the width of 250mm and the height of 250 mm;
(3) keeping the square ingot blank obtained in the step (2) at 490 ℃ for 15h, then performing three-way forging by using a hydraulic press, and finally performing air cooling to room temperature to obtain a forged magnesium alloy; the rolling speed of the three-way forging is 6mm/s, and the total deformation of each pass is 20%;
(4) and (4) carrying out heat treatment on the forged magnesium alloy obtained in the step (3), wherein the heat treatment temperature is 350 ℃, the heat treatment time is 90min, and then air-cooling to room temperature to obtain the magnesium alloy large forging.
The mechanical properties of the magnesium alloy large forgings prepared in the examples 1-3 and the comparative examples 1-2 are shown in table 1:
table 1 mechanical properties of large magnesium alloy forgings prepared in examples 1-3 and comparative examples 1-2
Figure BDA0003279581830000101
Figure BDA0003279581830000111
According to the description of the embodiments 1 to 3, the diameter of the high-strength heat-resistant magnesium alloy large forging provided by the invention is larger than or equal to 900mm, the height of the high-strength heat-resistant magnesium alloy large forging is larger than or equal to 200mm, the axial tensile strength at room temperature is larger than or equal to 400MPa, the tangential tensile strength is larger than 350MPa, the axial yield strength is larger than or equal to 300MPa, the tangential yield strength is larger than or equal to 240MPa, the axial and tangential elongations are larger than or equal to 3.0%, the axial and tangential tensile strength of the high-strength heat-resistant magnesium alloy large forging at the temperature of 200 ℃ is larger than or equal to 300MPa, the axial and tangential yield strength is larger than or equal to 210MPa, and the axial and tangential elongations are larger than or equal to 6.0%, so that the high-strength heat-resistant magnesium alloy large forging has excellent mechanical properties.
According to the comparison between the embodiment 2 and the comparative example 1, the multidirectional forging process combining the radial high-speed forging and the axial slow-speed upsetting is compared with the conventional unidirectional forging process, the axial tensile strength and the tangential yield strength of the magnesium alloy large forging are greatly improved at room temperature and 200 ℃, and the elongation of the forging is equivalent to that of the comparative example 1.
According to the comparison between the embodiment 3 and the comparative example 2, the multidirectional forging process combining the radial high-speed forging and the axial slow-speed upsetting is compared with the conventional unidirectional forging process, the axial tensile strength and the tangential yield strength of the magnesium alloy large forging are greatly improved at room temperature and 200 ℃, and the elongation of the forging is equivalent to that of the comparative example 2.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (9)

1. A preparation method of a large high-strength heat-resistant magnesium alloy forging comprises the following steps:
(1) homogenizing a magnesium alloy ingot to obtain a pretreated magnesium alloy;
(2) preparing the pretreated magnesium alloy obtained in the step (1) into a cylindrical ingot blank;
(3) preserving the heat of the cylindrical ingot blank obtained in the step (2), and then performing radial forging to obtain a forged ingot blank;
(4) Carrying out temperature returning treatment on the forging ingot blank obtained in the step (3), and then carrying out axial upsetting to obtain an upset ingot blank;
(5) repeating the operation of the step (3) and the operation of the step (4) for 1-2 times to obtain a forged magnesium alloy;
(6) carrying out heat treatment on the forged magnesium alloy obtained in the step (5) to obtain a high-strength heat-resistant magnesium alloy large forging;
in the step (2), the diameter of the cylindrical ingot blank is more than or equal to 900mm, and the height of the cylindrical ingot blank is more than or equal to 200 mm;
the parameters of the radial forging in the step (3) and the step (5) are independently: the frequency is 20-200 times/min, and the strain rate is 10-200 s-1; the deformation of each radial forging is 1-5%;
the parameters of the axial upsetting in the step (4) and the step (5) are independently as follows: the reduction speed is 6-10 mm/s, and the pass deformation is 20-40%;
and (5) when the step (3) is repeated, the heat preservation temperature is 5-20 ℃ lower than that of the last time, and the heat preservation time is 0.5-2 h.
2. The preparation method according to claim 1, wherein the magnesium alloy ingot in the step (1) comprises the following components in percentage by mass: gd: 7-13%, Y: 2.5-6%, Zr: 0.35-0.8% and the balance of Mg.
3. The preparation method according to claim 1, wherein the temperature of the homogenization treatment in the step (1) is 490 to 540 ℃ and the time of the homogenization treatment is 20 to 25 hours.
4. The preparation method according to claim 1, wherein the temperature for heat preservation in the step (3) is 460-510 ℃, and the time for heat preservation is 12-16 h.
5. The preparation method according to claim 1, wherein the temperature for heat preservation in the step (3) is 470-500 ℃, and the time for heat preservation is 13-15 h.
6. The preparation method according to claim 1, wherein the temperature of the tempering treatment in the step (4) and the step (5) is 380-410 ℃, and the time of the tempering treatment is 1-2 h.
7. The production method as claimed in claim 1, wherein the height of the upset ingot in step (4) is the same as the height of the cylindrical ingot in step (2).
8. The method according to claim 1, wherein the heat treatment in step (6) is performed at a temperature of 350 to 450 ℃ for 30 to 120 min.
9. The high-strength heat-resistant magnesium alloy large forging prepared by the preparation method of any one of claims 1-8.
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CN117259635B (en) * 2023-09-18 2024-05-14 中南大学 Preparation method of VW93M magnesium alloy medium plate
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