CN114196894A - 7XXX series aluminum alloy residual stress reduction method for aviation - Google Patents
7XXX series aluminum alloy residual stress reduction method for aviation Download PDFInfo
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- CN114196894A CN114196894A CN202111244741.0A CN202111244741A CN114196894A CN 114196894 A CN114196894 A CN 114196894A CN 202111244741 A CN202111244741 A CN 202111244741A CN 114196894 A CN114196894 A CN 114196894A
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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
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/053—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with zinc as the next major constituent
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/002—Hybrid process, e.g. forging following casting
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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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
- C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
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Abstract
The invention belongs to the technical field of residual stress relief of non-ferrous metal forgings, and discloses a 7XXX series aluminum alloy residual stress reduction method for aviation. A method for reducing residual stress of 7XXX series aluminum alloy for aviation comprises the following steps: the method comprises the following steps: carrying out thermoplastic deformation on a 7XXX series aluminum alloy bar on a press machine, and carrying out air cooling after the thermoplastic deformation; step two: carrying out solution treatment on the forged piece subjected to the thermoplastic deformation in the step one; step three: performing cold plastic deformation on the forge piece after the solution treatment; step four: carrying out first artificial aging on the forged piece after cold plastic deformation; step five: and carrying out secondary artificial aging on the forged piece subjected to the primary artificial aging. The invention cancels the traditional homogenization annealing system to eliminate the residual stress of the distortion shape in the forging, saves the heat energy consumption and improves the production efficiency.
Description
Technical Field
The invention belongs to the technical field of residual stress relief of non-ferrous metal forgings, and particularly relates to a 7XXX series aluminum alloy residual stress reduction method for aviation.
Background
With the development of lightweight, large-sized and high-speed aviation military aircraft, aluminum alloys are increasingly widely used as light-weight and corrosion-resistant representatives. The 7XXX series aluminum alloy belongs to Al-Zn high-strength hard aluminum, has high strength, high fracture toughness and excellent stress corrosion capability compared with other aluminum alloys, and is widely applied to parts of an airplane with high requirements on fatigue strength, fracture toughness and stress corrosion capability, such as a girder edge strip, a fuselage skin, a lower airfoil stringer and the like. Typical Al-Zn-Mg-Cu aluminum alloys for aviation include: 7a04, 7050, 7B04, etc., the heat treatment conditions used were: t6, T73, T74, T7451, T7452, etc.
After plastic deformation, 10% of work of an external force on metal is converted into internal stress, and residual stress is formed. The distortion of the lattice in the vicinity thereof due to the generation of lattice defects such as dislocations is a main residual stress in the metal. Residual stresses not only reduce the strength of the metal, but also cause the forging to deform due to subsequent stress relaxation or redistribution.
At present, after an Al-Zn-Mg-Cu series aluminum alloy forging is formed, the required mechanical property is obtained by adopting heat treatment strengthening (solid solution treatment and aging heat treatment). The residual stress eliminating method adopts heat treatment annealing, and the effect can only reach 40 percent expected. For large aluminum alloy forgings, the forging is large in size and complex in shape, and thermal stress and structural stress easily exist after heat treatment. When the maximum deformation amount exceeds the machining allowance in subsequent machining, the forge piece is warped due to residual stress, meanwhile, the corrosion resistance is also reduced, and finally scrapping is caused.
Therefore, there is a strong need for new methods for reducing residual stresses left by Al-Zn-Mg-Cu aluminum alloys after thermoplastic deformation and heat treatment in solution.
Disclosure of Invention
The purpose of the invention is as follows: the problems of uneven thermoplastic deformation of the forge piece and overlarge residual stress after heat treatment are solved, and the possibility of stress corrosion and the probability of fatigue failure in the use of an installation machine are reduced.
In order to solve the technical problem, the technical scheme of the invention is as follows:
a method for reducing residual stress of 7XXX series aluminum alloy for aviation comprises the following steps:
the method comprises the following steps: carrying out thermoplastic deformation on a 7XXX series aluminum alloy bar on a press machine, and carrying out air cooling after the thermoplastic deformation;
step two: carrying out solution treatment on the forged piece subjected to the thermoplastic deformation in the step one;
step three: performing cold plastic deformation on the forge piece after the solution treatment;
step four: carrying out first artificial aging on the forged piece after cold plastic deformation;
step five: and carrying out secondary artificial aging on the forged piece subjected to the primary artificial aging.
Further, in the first step, a 7XXX series aluminum alloy bar is heated to 420-470 ℃ during thermoplastic deformation; the deformation rate is 10 mm/s-15 mm/s.
Further, in the second step, the temperature of the solution treatment is 450-500 ℃, and the time of the solution treatment is 4-8 h.
Further, the second step also comprises the step of cooling the forging to room temperature by adopting water with the temperature of 10-50 ℃ after the solution treatment is finished, wherein the cooling time is not less than 30 min.
And further, before cold plastic deformation in the third step, the forging piece cooled to room temperature is placed for 12-36 hours at room temperature.
Further, in the third step, the deformation amount of the cold plastic deformation is 1% -10%.
Further, in the fourth step, the temperature of the first artificial aging is 100-140 ℃, the duration is 6-10 h, and the air is cooled to the room temperature after the first artificial aging is finished.
Further, in the fifth step, the temperature of the second artificial aging is 160-200 ℃, the duration time is 9-12 h, and the air is cooled to the room temperature after the second artificial aging is finished.
Compared with the traditional process, the invention has the following advantages:
1. after the Al-Zn-Mg-Cu aluminum alloy for aviation is subjected to thermoplastic deformation, the traditional homogenization annealing system is cancelled to eliminate the distortion residual stress in the forged piece, so that the heat energy consumption is saved, and the production efficiency is improved;
2. the heat treatment system is optimized: adopts a new method of solid solution treatment, cold plastic deformation treatment and graded artificial aging treatment. After the solid solution treatment, the complicated cryogenic treatment is reduced, cold plastic deformation is carried out, the deformation amount is set according to the states of heat treatment T73, T74, T7451, T7452 and the like, and the residual stress and the residual deformation generated by solid solution are greatly reduced by combining with graded artificial aging;
3. reducing the possibility of stress corrosion and the chance of fatigue failure in the use of the machine.
Drawings
FIG. 1 is a schematic flow chart of a method for reducing residual stress of a 7XXX series aluminum alloy for aviation.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. 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.
The invention provides a method for reducing residual stress of a 7XXX series aluminum alloy for aviation, which comprises the following steps:
1) and (4) performing thermoplastic deformation forging. Heating at 420-470 ℃ and with a deformation rate of 10-15 mm/s; distributing deformation heat according to the size, forming and forging, and air cooling; the 7XXX series aluminum alloy has better plasticity at 420-470 ℃ and is convenient for forging and forming.
2) And (4) solution treatment. Heating temperature: the temperature is 450-500 ℃, the heat preservation time is 4-8 h, the cooling medium adopts water with the temperature of 10-50 ℃, the cooling speed is close to the critical cooling speed of phase change, and the cooling time is not less than 30 min; and carrying out cold plastic deformation after standing for 24 h. The aluminum alloy forging after solution treatment at 450-500 ℃ and cooling at the speed close to the critical cooling speed of phase change has excellent room temperature performances such as tensile property, yield property and the like.
The residual stress formed by solid solution is the main factor of deformation of the aluminum alloy forging after heat treatment or mechanical processing. By adopting cold forging compression deformation, the deformation amount is 1-10% (specifically according to the thickness of the forged piece), and the residual stress after the solution treatment can be reduced. The free forging with constant section is directly compressed and deformed, and the die forging with a certain shape needs to be compressed and deformed in a special die.
3) And (5) cold plastic deformation. And (3) performing cold forging compression deformation by a press, wherein the deformation is 1-10%, and the deformation is adjusted according to the thickness of the forged piece and exceeds 1% so as to fully reduce the residual stress after the solution treatment.
4) And (5) grading artificial aging. Carrying out first artificial aging at the temperature of 100-140 ℃, keeping the temperature for 6-10 h, and carrying out air cooling; and (4) carrying out secondary artificial aging by grading aging at 160-200 ℃, keeping the temperature for 9-12 h, and carrying out air cooling. The first artificial aging is carried out at a lower temperature, so that the dispersion degree of the intermediate phase can be increased, the uniformity of the structure is improved, the second artificial aging is higher in temperature and longer in heat preservation time than the first artificial aging, the structure, the size and the dispersion degree of a precipitation phase are adjusted, the stress corrosion resistance is obviously improved, and the forge piece with excellent comprehensive performance is further obtained.
Example one
The material of a crossbeam flange strip of an airplane is 7A04, and the forged piece is a free forged piece with the specification of
The unit mm.
(1) And (4) performing thermoplastic deformation forging. The temperature is 440 ℃, and the forming is carried out by 3 fire, and the details are shown in the following table 1:
(2) and (4) solution treatment. The temperature is 480 ℃, the heat preservation time is 5.5 hours, and the cooling medium is water (the water temperature is 70 ℃);
(3) and (5) cold plastic deformation. Performing cold plastic deformation forging on the forging by using a 16MN free forging press, wherein the deformation is 6% of the effective section thickness of the forging;
(4) and (5) grading artificial aging. Primary artificial aging, heating temperature: 135 ℃, heat preservation time: air cooling for 9 h; secondary artificial aging, heating temperature: 195 ℃, holding time: air cooling for 12 h;
after the treatment, the Al-Zn-Mg-Cu series 7A04 aluminum alloy forging for aviation in the embodiment is obtained by the following steps: the yield strength, tensile strength, elongation, etc. are all greatly improved and have a lower residual stress state, as shown in table 2 below.
TABLE 1
TABLE 2
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present invention, and these modifications or substitutions should be covered within the scope of the present invention.
Claims (8)
1. A method for reducing residual stress of 7XXX series aluminum alloy for aviation is characterized by comprising the following steps: the method comprises the following steps:
the method comprises the following steps: carrying out thermoplastic deformation on a 7XXX series aluminum alloy bar on a press machine, and carrying out air cooling after the thermoplastic deformation;
step two: carrying out solution treatment on the forged piece subjected to the thermoplastic deformation in the step one;
step three: performing cold plastic deformation on the forge piece after the solution treatment;
step four: carrying out first artificial aging on the forged piece after cold plastic deformation;
step five: and carrying out secondary artificial aging on the forged piece subjected to the primary artificial aging.
2. The method for reducing the residual stress of the 7XXX series aluminum alloy for aviation according to claim 1, wherein: in the first step, a 7XXX series aluminum alloy bar is heated to 420-470 ℃ during thermoplastic deformation; the deformation rate is 10 mm/s-15 mm/s.
3. The method for reducing the residual stress of the 7XXX series aluminum alloy for aviation according to claim 2, wherein: in the second step, the temperature of the solution treatment is 450-500 ℃, and the time of the solution treatment is 4-8 h.
4. The method for reducing the residual stress of the 7XXX series aluminum alloy for aviation according to claim 3, wherein: and step two, cooling the forging to room temperature by adopting water at 10-50 ℃ after the solution treatment is finished, wherein the cooling time is not less than 30 min.
5. The method for reducing the residual stress of the 7XXX series aluminum alloy for aviation according to claim 4, wherein: and (3) placing the forged piece cooled to room temperature for 12-36 h at room temperature before cold plastic deformation in the third step.
6. The method for reducing the residual stress of the 7XXX series aluminum alloy for aviation according to claim 5, wherein: in the third step, the deformation amount of the cold plastic deformation is 1 to 10 percent.
7. The method for reducing the residual stress of the 7XXX series aluminum alloy for aviation according to claim 6, wherein: in the fourth step, the temperature of the first artificial aging is 100-140 ℃, the duration is 6-10 h, and the air is cooled to the room temperature after the first artificial aging is finished.
8. The method for reducing the residual stress of the 7XXX series aluminum alloy for aviation according to claim 7, wherein: in the fifth step, the temperature of the second artificial aging is 160-200 ℃, the duration time is 9-12 h, and the air is cooled to the room temperature after the second artificial aging is finished.
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Citations (5)
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|---|---|---|---|---|
| CN104745985A (en) * | 2013-12-25 | 2015-07-01 | 青岛玉光精铸厂 | Heat treatment technology of 7050 high-strength aluminum alloy forge piece |
| CN104846302A (en) * | 2015-06-02 | 2015-08-19 | 湖南大学 | Ageing heat treatment method for keeping aluminum alloy strength and reducing quenching residual stress |
| CN105088113A (en) * | 2015-08-27 | 2015-11-25 | 东北轻合金有限责任公司 | Method for manufacturing aluminum alloy free forge piece for spaceflight |
| CN107999687A (en) * | 2017-11-29 | 2018-05-08 | 无锡透平叶片有限公司 | A kind of aluminium alloy vane forging and preparation method thereof |
| CN112647032A (en) * | 2020-12-02 | 2021-04-13 | 贵州航天新力科技有限公司 | Processing method for integrally forming 7-series aluminum alloy annular part |
-
2021
- 2021-10-25 CN CN202111244741.0A patent/CN114196894A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104745985A (en) * | 2013-12-25 | 2015-07-01 | 青岛玉光精铸厂 | Heat treatment technology of 7050 high-strength aluminum alloy forge piece |
| CN104846302A (en) * | 2015-06-02 | 2015-08-19 | 湖南大学 | Ageing heat treatment method for keeping aluminum alloy strength and reducing quenching residual stress |
| CN105088113A (en) * | 2015-08-27 | 2015-11-25 | 东北轻合金有限责任公司 | Method for manufacturing aluminum alloy free forge piece for spaceflight |
| CN107999687A (en) * | 2017-11-29 | 2018-05-08 | 无锡透平叶片有限公司 | A kind of aluminium alloy vane forging and preparation method thereof |
| CN112647032A (en) * | 2020-12-02 | 2021-04-13 | 贵州航天新力科技有限公司 | Processing method for integrally forming 7-series aluminum alloy annular part |
Non-Patent Citations (2)
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Application publication date: 20220318 |