CN108624830B - Magnesium alloy structural part and extrusion preparation method thereof - Google Patents
Magnesium alloy structural part and extrusion preparation method thereof Download PDFInfo
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- CN108624830B CN108624830B CN201810347456.3A CN201810347456A CN108624830B CN 108624830 B CN108624830 B CN 108624830B CN 201810347456 A CN201810347456 A CN 201810347456A CN 108624830 B CN108624830 B CN 108624830B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/06—Changing 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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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C23/00—Alloys based on magnesium
- C22C23/02—Alloys based on magnesium with aluminium as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C23/00—Alloys based on magnesium
- C22C23/04—Alloys based on magnesium with zinc or cadmium as the next major constituent
Abstract
The invention discloses an extrusion preparation method of a magnesium alloy structural member, which is characterized in that a magnesium alloy ingot comprises the following components in percentage by mass: 2.20% -3.20%, Al: 2.60% -3.40%, Ti: 0.20-0.80%, Y: 0.40% -1.50% of Mg and unremovable impurity elements, comprising the following steps: a: manufacturing a cuboid magnesium alloy blank; b: extrusion forming; c: and (4) aging heat treatment. By adopting two times of extrusion and two times of different heat treatments, the alloy has no cracking condition, crystal grains in the alloy are obviously refined, dislocation is greatly multiplied, and a large amount of twin crystals are generated at crystal boundaries, so that the mechanical property is obviously improved, and after the two times of extrusion, the tensile strength of the prepared sample piece is more than or equal to 365Mpa, the yield strength is more than or equal to 240Mpa, and the elongation is more than or equal to 6%; and then the complex magnesium alloy structural part with the tensile strength of more than or equal to 380MPa, the yield strength of more than or equal to 255MPa and the elongation of more than or equal to 8% at normal temperature is obtained through aging treatment, and the use requirement is met.
Description
Technical Field
The invention relates to the field of magnesium alloy deformation processing and extrusion forming, in particular to an extrusion preparation method of a magnesium alloy structural member.
Background
The magnesium alloy has the advantages of small density, high specific strength, large specific modulus of elasticity, good heat dissipation, easy cutting and processing, good electromagnetic shielding performance, damping and vibration reduction performance, low processing cost and the like, is an ideal material for components and parts such as aerospace, weaponry, automobiles, 3C products and the like, and can be widely applied to the industrial fields such as aerospace, weaponry, automobiles, electronic and electrical products and the like. In order to prepare a large-size high-strength and high-toughness complex magnesium alloy structural member, a magnesium alloy plastic forming process becomes an important subject in the field of material processing, and as the magnesium alloy belongs to a close-packed hexagonal crystal (hcp) structure, the slippage system is relatively less, the plastic deformation capability is poor at room temperature, and the plastic forming is difficult, and the problem is difficult to solve by the traditional plastic processing technology. The invention name of the publication No. CN107747014A is 'a high-ductility and high-strength magnesium alloy and a preparation method thereof', and the mass percentages are as follows: 6.0-9.0% of Zn, 3.0-6.0% of Gd, 0.4-1.0% of Zr, 0.05-0.20% of Sr and 0.05-1.5% of Y, Mg as the balance, and a preparation method thereof, wherein the magnesium alloy ingot blank is extruded in an extrusion cylinder at the extrusion speed of 1.0-5.0 m/min, the preheating temperature of the extrusion cylinder is 300-400 ℃, and the extrusion ratio is 10-50: 1, and the technical scheme for obtaining the extrusion bar is described, and the method for preparing the large-size high-strength-toughness complex magnesium alloy extrusion structural member by adopting the extrusion process is not involved.
Disclosure of Invention
The embodiment of the invention provides an extrusion preparation method of a magnesium alloy structural member, and solves the problems that in the prior art, as the magnesium alloy belongs to a close-packed hexagonal crystal structure, the slippage system is relatively less, the plastic deformation capability is poor at room temperature, and the large-size high-strength-toughness complex magnesium alloy structural member is difficult to be prepared by plastic forming.
The invention provides a preparation method of a large-size high-strength tough magnesium alloy extrusion piece, which is realized by the following technical scheme:
the extrusion preparation method of the magnesium alloy structural part is characterized in that the magnesium alloy ingot comprises the following components in percentage by mass: 2.20% -3.20%, Al: 2.60% -3.40%, Ti: 0.20-0.80%, Y: 0.40% -1.50% of Mg and unremovable impurity elements, comprising the following steps:
a: manufacturing a cuboid magnesium alloy blank;
b: extrusion forming;
c: and (4) aging heat treatment.
Specifically, the specification of the cuboid magnesium alloy blank manufactured in the step A is as follows: 100mm to 3000mm long, 100mm to 2000mm wide and 100mm to 300mm high.
Specifically, in the extrusion forming process of the step B, the primary preheating temperature of the blank is 450-480 ℃, and the processing time is 1-4 h; the preheating temperature of an extrusion die is 450-480 ℃, the processing time is 2-6 h, the extrusion speed is controlled in the extrusion process, the extrusion speed is 1-10 mm/s, and the extrusion ratio is 80-120; the secondary heat treatment temperature of the blank is 300-350 ℃, and the treatment time is 1-4 h; the preheating temperature of the extrusion die is 300-350 ℃, the processing time is 1-4 h, the extrusion speed is controlled in the secondary extrusion process, the extrusion speed is 0.1-4 mm/s, and the extrusion ratio is 40-80, so that the magnesium alloy extrusion piece is prepared.
Preferably, a water-based graphite lubricant is used in the extrusion forming process in the step B, wherein the water-based graphite lubricant takes water as a solvent and comprises 15-20 wt% of graphite, 20-25 wt% of sodium carbonate, 3-6 wt% of a surfactant and 2-6 wt% of a dispersant.
Specifically, in the step C, the magnesium alloy extrusion piece prepared in the step B is subjected to aging treatment after turning, the aging treatment temperature is 175-190 ℃, the temperature is kept for 18-30 h, and then the magnesium alloy extrusion piece is air-cooled to the room temperature.
The invention also provides a magnesium alloy structural member prepared by the preparation method.
Furthermore, the tensile strength of the magnesium alloy structural part at normal temperature is more than or equal to 380MPa, the yield strength is more than or equal to 255MPa, and the elongation is more than or equal to 8%.
Further, the magnesium alloy structural member is a structural member with a complex shape, as shown in fig. 1.
According to the preparation process of the large-size high-strength tough magnesium alloy extrusion piece, two times of extrusion are adopted, and two times of different heat treatment are carried out, so that the alloy does not crack, crystal grains in the alloy are obviously refined, dislocation is greatly multiplied, and a large number of twin crystals are generated at crystal boundaries, so that the mechanical property is obviously improved, and after the two times of extrusion, the tensile strength of the prepared sample piece is more than or equal to 365MPa, the yield strength is more than or equal to 240MPa, and the elongation is more than or equal to 6 percent at room temperature; and then the complex magnesium alloy structural part with the tensile strength of more than or equal to 380MPa, the yield strength of more than or equal to 255MPa and the elongation of more than or equal to 8% at normal temperature is obtained through aging treatment, and the use requirement is met. The invention explores a large-size high-strength and high-toughness complex magnesium alloy structural member extrusion preparation process, which has important significance for meeting the requirements of large-size high-strength and high-toughness complex magnesium alloy structural members in the fields of aerospace, military weaponry and the like.
Drawings
Fig. 1 is a schematic view of a magnesium alloy complex-shaped structural member.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Example 1: the method comprises the steps of firstly carrying out homogenization heat treatment on a magnesium alloy blank, heating the magnesium alloy blank to 480 ℃, keeping the temperature for 1 hour, preheating the extrusion die to 480 ℃, keeping the temperature for 2 hours, extruding the preheated magnesium alloy blank, preparing the preheated magnesium alloy blank at a ratio of water-based graphite serving as a lubricant and water serving as a solvent, wherein the ratio of graphite to soda is 20 percent, the ratio of surfactant to surfactant is 6 percent, and the ratio of dispersing agent to be 4 percent, wherein the extrusion speed is 8mm/s, the extrusion ratio is 90 percent, carrying out secondary heat treatment after air cooling, carrying out temperature preservation at 300 ℃, keeping the temperature for 2 hours, the secondary extrusion speed at 2mm/s, and the extrusion ratio is 55, carrying out aging treatment on the prepared large-size high-strength tough magnesium alloy extrusion piece after air cooling, wherein the aging treatment temperature is.
The room temperature mechanical property test is carried out according to GB/T228-2002, and the results are shown in Table 1.
Example 2: the method comprises the steps of firstly carrying out homogenization heat treatment on a magnesium alloy blank, heating the magnesium alloy blank to 460 ℃, keeping the temperature for 3 hours, preheating an extrusion die to 460 ℃, keeping the temperature for 3 hours, extruding the preheated magnesium alloy blank, preparing the preheated magnesium alloy blank according to the proportion of water-based graphite serving as a lubricant and water serving as a solvent, wherein the graphite accounts for 15 percent, the soda accounts for 20 percent, the surfactant accounts for 5 percent, and the dispersant accounts for 6 percent, extruding at the speed of 5mm/s and the extrusion ratio of 100 percent, carrying out secondary heat treatment after air cooling at the temperature of 350 ℃, keeping the temperature for 1 hour, carrying out secondary extrusion at the speed of 3mm/s and the extrusion ratio of 60, carrying out aging treatment on the prepared large-size high-strength tough magnesium alloy extrusion piece after air cooling, keeping the temperature at 175 ℃.
The room temperature mechanical property test is carried out according to GB/T228-2002, and the results are shown in Table 1.
Example 3: the method comprises the steps of firstly carrying out homogenization heat treatment on a magnesium alloy blank, heating the magnesium alloy blank to 450 ℃, keeping the temperature for 2 hours, preheating the extrusion die to 450 ℃, keeping the temperature for 2 hours, extruding the preheated magnesium alloy blank, preparing the preheated magnesium alloy blank according to the proportion of water-based graphite serving as a lubricant and water serving as a solvent, wherein the graphite is 18 percent, the soda is 24 percent, the surfactant is 4 percent and the dispersant is 2 percent, extruding the magnesium alloy blank at the speed of 4mm/s and the extrusion ratio of 120, carrying out secondary heat treatment after air cooling, carrying out temperature preservation for 2 hours, carrying out secondary extrusion at the speed of 1mm/s and the extrusion ratio of 40, carrying out aging treatment on the prepared large-size high-strength tough magnesium alloy extrusion piece after air cooling, wherein the aging treatment temperature is 180 ℃, keeping the temperature for 24.
The room temperature mechanical property test is carried out according to GB/T228-2002, and the results are shown in Table 1.
Comparative example: the method comprises the steps of firstly carrying out homogenization heat treatment on a magnesium alloy blank, heating the magnesium alloy blank at 400 ℃, keeping the temperature for 6 hours, preheating an extrusion die at 400 ℃, keeping the temperature for 6 hours, extruding the preheated magnesium alloy blank, preparing the preheated magnesium alloy blank at a ratio of water-based graphite serving as a lubricant and water serving as a solvent, wherein the ratio of graphite to sodium carbonate is 10 percent, a surfactant is 4 percent, and a dispersant is 2 percent, carrying out extrusion at a speed of 12mm/s and an extrusion ratio of 50, carrying out secondary heat treatment after air cooling at a temperature of 200 ℃, keeping the temperature for 2 hours, carrying out secondary extrusion at a speed of 1mm/s and an extrusion ratio of 30, carrying out aging treatment on the prepared large-size high-strength tough magnesium alloy extrusion piece after air cooling, wherein the aging treatment temperature is 200 ℃, keeping the temperature.
The results of room temperature mechanical property tests according to GB/T228-2002 are shown in Table 1, and the results in the table show that the magnesium alloy structural part prepared by the method meets the requirements of the tensile strength of more than or equal to 380MPa, the yield strength of more than or equal to 255MPa and the elongation of more than or equal to 8% at normal temperature, and the magnesium alloy structural part prepared by the method in the prior art has obvious difference in performance.
TABLE 1 mechanical property table of magnesium alloy prepared by the embodiment of the invention
| Tensile strength/MPa | Yield strength/MPa | Elongation/percent | |
| Example 1 | 386 | 262 | 8.3 |
| Example 2 | 385 | 258 | 8.6 |
| Example 3 | 391 | 274 | 8.1 |
| Comparative examples | 362 | 241 | 6.5 |
Claims (4)
1. The extrusion preparation method of the magnesium alloy structural part is characterized in that the magnesium alloy ingot comprises the following components in percentage by mass: 2.20% -3.20%, Al: 2.60% -3.40%, Ti: 0.20-0.80%, Y: 0.4% -1.50%, the balance being Mg and non-removable impurity elements, comprising the steps of:
a: manufacturing a cuboid magnesium alloy blank;
b: extrusion forming;
c: aging heat treatment;
the specification of the cuboid magnesium alloy blank manufactured in the step A is as follows: the length is 100 mm-3000 mm, the width is 100 mm-2000 mm, and the height is 100 mm-300 mm;
b, in the extrusion forming process of the step B, the primary preheating temperature of the blank is 450-480 ℃, and the processing time is 1-4 h; the preheating temperature of an extrusion die is 450-480 ℃, the processing time is 2-6 h, the extrusion speed is controlled in the extrusion process, the extrusion speed is 1-10 mm/s, and the extrusion ratio is 80-120; the secondary heat treatment temperature of the blank is 300-350 ℃, and the treatment time is 1-4 h; preheating the extrusion die at 300-350 ℃, treating for 1-4 h, controlling the extrusion speed in the secondary extrusion process, wherein the extrusion speed is 0.1-4 mm/s, and the extrusion ratio is 40-80, so as to prepare a magnesium alloy extrusion piece;
and C, turning the magnesium alloy extrusion piece obtained in the step B, performing aging treatment at 175-190 ℃, preserving heat for 18-30 h, and then air-cooling to room temperature.
2. The extrusion preparation method of the magnesium alloy structural member according to claim 1, wherein: and B, using a water-based graphite lubricant in the extrusion forming process, wherein the water-based graphite lubricant takes water as a solvent and comprises 15-20 wt% of graphite, 20-25 wt% of sodium carbonate, 3-6 wt% of a surfactant and 2-6 wt% of a dispersant.
3. A magnesium alloy structural member characterized by being produced by the production method as set forth in any one of claims 1 to 2.
4. The magnesium alloy structural member according to claim 3, wherein the magnesium alloy structural member has a tensile strength of 380MPa or more, a yield strength of 255MPa or more, and an elongation of 8% or more at room temperature.
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| CN112442621A (en) * | 2020-11-04 | 2021-03-05 | 长沙新材料产业研究院有限公司 | Magnesium alloy plate and preparation method thereof |
| CN112458348A (en) * | 2020-11-04 | 2021-03-09 | 长沙新材料产业研究院有限公司 | Magnesium alloy semicircular ring section bar and preparation method thereof |
| CN112547826B (en) * | 2020-12-24 | 2022-11-11 | 中国兵器工业第五九研究所 | Magnesium alloy forming method with gradient temperature and rate field |
| CN114892055B (en) * | 2022-05-25 | 2023-09-05 | 鹤壁海镁科技有限公司 | High-strength and high-toughness Mg-Al-Zn magnesium alloy and preparation method thereof |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102634710A (en) * | 2012-05-07 | 2012-08-15 | 东莞市闻誉实业有限公司 | Al-Zn-Mg alloy and preparation method thereof |
| CN104561710A (en) * | 2013-10-15 | 2015-04-29 | 天津东义镁制品股份有限公司 | High-strength magnesium alloy and preparation method thereof |
| CN105506426A (en) * | 2016-01-28 | 2016-04-20 | 北京工业大学 | Multi-nanophase composite enhanced magnesium alloy and preparation method thereof |
| CN105951013A (en) * | 2016-06-27 | 2016-09-21 | 湖南航天新材料技术研究院有限公司 | Multi-stage heat treatment strengthening technology of low-alloying magnesium alloy |
| CN106521381A (en) * | 2016-11-03 | 2017-03-22 | 湖南航天新材料技术研究院有限公司 | Preparation technology for large size super-high obdurability magnesium alloy thin plate |
| CN107099762A (en) * | 2017-03-27 | 2017-08-29 | 清华大学深圳研究生院 | A kind of Hot Deformation Strengthening method of magnesium-rare earth |
| CN107177762A (en) * | 2017-05-18 | 2017-09-19 | 湖南金戈新材料有限责任公司 | The secondary hot extrusion technique of AQ80M magnesium alloy profiles |
| CN107177763A (en) * | 2017-05-18 | 2017-09-19 | 湖南金戈新材料有限责任公司 | The secondary hot extrusion technique of AQ80M magnesium alloy plates |
-
2018
- 2018-04-18 CN CN201810347456.3A patent/CN108624830B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102634710A (en) * | 2012-05-07 | 2012-08-15 | 东莞市闻誉实业有限公司 | Al-Zn-Mg alloy and preparation method thereof |
| CN104561710A (en) * | 2013-10-15 | 2015-04-29 | 天津东义镁制品股份有限公司 | High-strength magnesium alloy and preparation method thereof |
| CN105506426A (en) * | 2016-01-28 | 2016-04-20 | 北京工业大学 | Multi-nanophase composite enhanced magnesium alloy and preparation method thereof |
| CN105951013A (en) * | 2016-06-27 | 2016-09-21 | 湖南航天新材料技术研究院有限公司 | Multi-stage heat treatment strengthening technology of low-alloying magnesium alloy |
| CN106521381A (en) * | 2016-11-03 | 2017-03-22 | 湖南航天新材料技术研究院有限公司 | Preparation technology for large size super-high obdurability magnesium alloy thin plate |
| CN107099762A (en) * | 2017-03-27 | 2017-08-29 | 清华大学深圳研究生院 | A kind of Hot Deformation Strengthening method of magnesium-rare earth |
| CN107177762A (en) * | 2017-05-18 | 2017-09-19 | 湖南金戈新材料有限责任公司 | The secondary hot extrusion technique of AQ80M magnesium alloy profiles |
| CN107177763A (en) * | 2017-05-18 | 2017-09-19 | 湖南金戈新材料有限责任公司 | The secondary hot extrusion technique of AQ80M magnesium alloy plates |
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