CN112725711A - Method for improving fatigue performance of high-strength aluminum alloy - Google Patents
Method for improving fatigue performance of high-strength aluminum alloy Download PDFInfo
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- CN112725711A CN112725711A CN202011520347.0A CN202011520347A CN112725711A CN 112725711 A CN112725711 A CN 112725711A CN 202011520347 A CN202011520347 A CN 202011520347A CN 112725711 A CN112725711 A CN 112725711A
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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
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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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0075—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rods of limited length
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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
Abstract
The invention belongs to the field of metal materials, and relates to a method for improving fatigue property of high-strength aluminum alloy. Before the solution heat treatment of the aluminum alloy bar, the aluminum alloy is heated to a certain temperature, generally not higher than 400 ℃, a clamp is used for clamping two ends of the aluminum alloy bar, mechanical twisting is carried out, one or more times of twisting treatment can be carried out, and the twisting device is provided with a clamping part for preventing bending deformation in the twisting process. The large-size inclusion or refractory phase is crushed by torsion, the purpose of reducing the size of the inclusion or refractory phase is achieved, the size of the inclusion or refractory phase is controlled within a certain range, and the fatigue performance and the mechanical property of a final product are improved by refining grains through recrystallization.
Description
Technical Field
The invention belongs to the field of metal materials, and particularly relates to a method for improving fatigue performance of high-strength aluminum alloy.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
With the continuous improvement of the strength of the aluminum alloy, the aluminum alloy is more and more widely applied to the industries of transportation and the like, such as Al-Mg-Zn series aluminum alloy. However, in the using process, the aluminum alloy structural material with high alloy elements is found to be used in severe environments such as complex external environment, high bearing capacity, frequent acceleration and deceleration and the like, and fatigue failure may be generated early, so that the designed service life of the product cannot be reached. The current research results show that the fatigue limit strength of steel increases linearly with the increase of the tensile strength of the steel, but the fatigue limit strength of aluminum alloy increases nonlinearly, and the fatigue limit strength increases extremely slowly with the increase of the tensile strength of the aluminum alloy. The main positions for forming fatigue crack sources in the industrial aluminum alloy comprise positions such as holes, inclusions, large-size refractory crystalline phases, stress concentration and the like, and regions with nonuniform microstructure characteristics and chemical compositions of the material. In general, large-sized inclusions or refractory phases tend to be a fatigue crack source, such as some Fe, Si intermetallic compounds and the like containing impurity elements, and particularly, inclusions or refractory phases having a size of more than 5 μm greatly reduce the fatigue strength of the aluminum alloy matrix.
However, the elimination of the refractory phase is not easy, the temperature adopted in the homogenization process or the solution heat treatment process is difficult to dissolve some refractory phases back into the aluminum alloy matrix, and the measures for controlling the coarse refractory phase commonly used at present include improving the purity of raw materials, adopting a filtering device, crushing coarse refractory materials into smaller particles through processing deformation and the like. Meanwhile, the current research results show that although the coarse refractory phase accelerates the fatigue crack initiation, the influence of the fine and dispersed refractory phase in the aluminum alloy on the fatigue performance is favorable, namely the improvement of the fatigue strength is favorable if the inclusion or the refractory phase can be controlled within a certain size range.
Disclosure of Invention
In order to improve the influence of large-size coarse inclusions or refractory phase on the fatigue life of the aluminum alloy, the invention provides a method for reducing the size distribution of the inclusions or refractory phase to improve the fatigue performance of the high-strength aluminum alloy. Before the solution heat treatment of the aluminum alloy bar, the aluminum alloy is heated to a certain temperature, generally not higher than 400 ℃, two ends of the aluminum alloy bar are clamped by a clamp for mechanical torsion, and one or more times of torsion treatment can be carried out. The large-size inclusion or refractory phase is crushed by torsion, so that the purpose of reducing the size of the inclusion or refractory phase is achieved, and the size of the inclusion or refractory phase is controlled within a certain range to improve the fatigue performance of a final product.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
in a first aspect of the present invention, there is provided a method for improving fatigue properties of a high strength aluminum alloy, comprising:
the aluminum alloy material is subjected to torsion treatment, solution treatment, quenching treatment and aging treatment, so that the aluminum alloy is conveniently subjected to large-deformation torsion, and the aluminum alloy is preferably heated before torsion and is generally not higher than 400 ℃.
The invention utilizes the torsion to crush large-sized inclusions or refractory phases, achieves the purpose of reducing the sizes of the inclusions or the refractory phases, controls the sizes of the inclusions or the refractory phases within a certain range and improves the fatigue performance of a final product. The treatment process not only can crush the inclusions or refractory phases through torsional deformation to reduce the size of the inclusions or refractory phases, but also can be beneficial to homogenization of alloy elements in the subsequent homogenization or solid solution process due to different degrees of element segregation in the casting process of the high-alloy aluminum alloy.
In a second aspect of the invention, there is provided a high strength aluminum alloy prepared by any of the above-described methods.
The fatigue performance of the high-strength aluminum alloy prepared by the invention is effectively improved, the grains are refined through recrystallization in the large deformation process, the mechanical property of the aluminum alloy can be improved, and the strength and the toughness are improved.
In a third aspect of the invention, the application of the high-strength aluminum alloy in the fields of transportation, packaging containers, architectural decoration, aerospace, mechanical and electrical appliances, electronic communication, petrochemical industry, energy power and physical hygiene is provided.
The method can effectively improve the fatigue performance of the high-strength aluminum alloy, so the method is expected to be widely applied to the fields of transportation, packaging containers, architectural decoration, aerospace, mechanical and electrical appliances, electronic communication, petrochemical industry, energy and power, and cultural and physical hygiene.
The invention has the beneficial effects that:
(1) the invention utilizes the torsion to crush large-sized inclusions or refractory phases, achieves the purpose of reducing the sizes of the inclusions or the refractory phases, controls the sizes of the inclusions or the refractory phases within a certain range and improves the fatigue performance of a final product. One of the advantages of the treatment process is that the size of inclusions or refractory phases can be reduced by large-deformation torsional extrusion crushing, and meanwhile, because high-alloy aluminum alloy often has element segregation in different degrees in the casting process, the homogenization of alloy elements in the subsequent homogenization or solution treatment process can be facilitated by the process.
(2) The invention has the additional advantage that the grains are refined through recrystallization in the large deformation process, namely the grains of the aluminum alloy matrix after solution treatment are fine, which is also beneficial to the fatigue property and the mechanical property of the final product.
(3) Selection of the twist working temperature before solution treatment: the lower the temperature, the more pronounced the work hardening of the aluminum alloy, the more pronounced the effect of breaking up inclusions or refractory phases, and the more pronounced the effect of refining the grains by recrystallization during the subsequent solution treatment. However, since the cast aluminum alloy has a large amount of precipitated phases and component segregation, and is highly brittle and likely to break during rotation, it is recommended to perform a large deformation and torsion treatment after heating to a certain temperature to increase plasticity to a certain degree. Too high a temperature does not have a significant effect on grain refinement.
(4) The preparation method is simple, convenient to operate, high in practicability and easy to popularize.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic view of a twisting apparatus of the present invention, wherein 1 an aluminum bar clamping and twisting apparatus, 2 an aluminum bar, 3 an external deflection preventing jig during twisting, 4 an external deflection preventing jig bolt during twisting;
FIG. 2 is a metallographic structure of an Al-Mg-Zn aluminum alloy after a process treatment, wherein the metallographic structure is obtained after a normal heat treatment in FIG. 2(a), and the metallographic structure is obtained by using the present invention in FIG. 2 (b).
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
A method for improving fatigue performance of a high-strength aluminum alloy comprises the following steps:
and sequentially carrying out torsion treatment, solution treatment, quenching treatment and aging treatment on the aluminum alloy material to obtain the aluminum alloy material.
In some embodiments, the aluminum alloy material is heated to 25 ℃ to 400 ℃ before being subjected to twisting treatment.
The type of the aluminum alloy material is not particularly limited in the present application, and the aluminum alloy material can be applied to 2-series aluminum alloys Al-Cu series and 7-series aluminum alloys Al-Mg-Zn series, or other aluminum alloys with higher content of alloy elements and easy existence of large-size inclusions or refractory phases, and in some embodiments, the aluminum alloy material is a high-alloy-content series aluminum alloy.
In some embodiments, the twisting is performed mechanically by clamping the two ends of the aluminum alloy material, and the aluminum alloy is externally provided with a device for preventing deflection deformation during twisting to prevent deformation instability during twisting.
In some embodiments, the twisting is performed one or more times.
The specific form of the solution treatment is not particularly limited in the present application, and in some embodiments, the solution treatment adopts a two-stage solution treatment, and the solution treatment has a good effect when applied to a 7-series alloy (i.e., Al-Mg-Zn series) with a high alloy content.
The specific process conditions of the solution treatment are not particularly limited in this application, and may be determined according to the system of the aluminum alloy, and in some embodiments, the specific process conditions of the two-stage solution treatment are as follows: preserving heat for 1-1.5 h at 470-475 ℃, and then preserving heat for 2-2.5 h at 485-490 ℃ so as to better treat 7 series aluminum alloy.
In some embodiments, the quenching process uses normal temperature water quenching.
The aging treatment of the invention is not limited to natural aging, and after the torsion is finished, the invention can be applied to any aluminum alloy with natural aging and artificial aging. In some embodiments, the high-iron 7N01 or aluminum alloy with close composition is subjected to natural aging in the manufacturing process, and the artificial aging treatment is also applied to 7075, 7055 and the like with higher alloy content.
The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.
In the following examples, the aluminum alloy used was an Al-Mg-Zn aluminum alloy, and the examples used specific compositions as follows: 4.4 wt% of Zn, 1.6 wt% of Mg, 0.4 wt% of Mn0.4 wt%, 0.2wt% of Cr0.2wt%, 0.2wt% of Zr0.2wt% of Cu0.2wt%, and Fe serving as an impurity and being controlled to be less than 0.4 wt%, and the balance being aluminum.
Example 1: conventional process
The alloy with the proportion is melted, refined, cast, and subjected to solid solution treatment after turning, wherein the solid solution treatment mainly adopts double-stage treatment, the temperature is kept at 470 ℃ for 1h, then kept at 485 ℃ for 2h, then quenched at room temperature, and then placed at room temperature for natural aging, namely T4 heat treatment process, the strength of the alloy is continuously improved along with the prolonging of the placing time, the tensile strength can reach more than 340MPa, and the fatigue strength is about 112 MPa. Fig. 2(a) is a metallographic structure obtained by a conventional preparation process.
Example 2: the process of the invention
The invention differs from example 1 in that: before the solution heat treatment, the aluminum alloy is heated to 250 ℃, after being uniformly heated, the aluminum alloy is taken out, quickly twisted for one week, put back into a furnace for the solution treatment process as in the step (1), then quenched at normal temperature, and naturally aged. The tensile strength of the final product can reach 362MPa, and the fatigue strength is improved to about 120 MPa. Fig. 2(b) is a metallographic structure obtained by the present invention, and compared with (a), it can be seen that the grains are significantly refined due to the formation of a large number of dislocations by the twisting process and the generation of a large number of re-crystallisations during the subsequent heat treatment process.
Example 3: the process of the invention
Similar to the example (2), except that the aluminum alloy is heated to 400 ℃, taken out after being uniformly heated, rapidly and continuously twisted for two weeks, put back into the furnace for the same solid solution process as the step (1), then quenched at normal temperature and naturally aged. The tensile strength of the final product can reach 365MPa, and the fatigue strength is improved to about 122 MPa.
EXAMPLE 4 twisting device
A torsion device for improving fatigue performance of high-strength aluminum alloy comprises: an aluminum bar external anti-torsion process instability deformation clamp 3 and an aluminum bar clamping and torsion device 1; the aluminum bar external clamp 3 is independent of the aluminum bar clamping and twisting device 1, the aluminum bar external deflection deformation preventing clamp 3 is fixed by the bolts 4 in the twisting process, the clamp 3 is independently assembled outside the aluminum bar 2 in the using process, and the twisting device 1 clamps the aluminum bar 2 for twisting operation.
The device can effectively prevent the aluminum alloy from deforming and destabilizing in the twisting process.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications and equivalents can be made in the technical solutions described in the foregoing embodiments, or equivalents thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. Although the present invention has been described with reference to the specific embodiments, it should be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (10)
1. A method for improving the fatigue property of high-strength aluminum alloy is characterized by comprising the following steps:
and (3) carrying out torsion treatment, solution treatment, quenching treatment and aging treatment on the aluminum alloy material to obtain the aluminum alloy material.
2. A method of improving fatigue performance of a high strength aluminum alloy according to claim 1, wherein said aluminum alloy material is a high alloy content series aluminum alloy.
3. The method for improving the fatigue strength of the high-strength aluminum alloy as claimed in claim 1, wherein the torsion is performed by mechanically clamping two ends of the aluminum alloy material, and a device for preventing the aluminum alloy from bending and deforming during the torsion is arranged outside the aluminum alloy in order to prevent the deformation and instability during the torsion.
4. A method of improving the fatigue performance of a high strength aluminum alloy according to claim 1, wherein said twisting is performed one or more times; preferably, the aluminum alloy material is heated to 25 ℃ to 400 ℃ before twisting.
5. A method of improving fatigue performance of a high strength aluminum alloy according to claim 1, wherein said solution treatment is a two-stage solution treatment.
6. The method for improving the fatigue performance of the high-strength aluminum alloy according to claim 5, wherein the specific process conditions of the double-stage solution treatment are as follows: preserving heat for 1-1.5 h at 470-475 ℃, and then preserving heat for 2-2.5 h at 485-490 ℃.
7. A method for improving fatigue performance of a high strength aluminum alloy as claimed in claim 1, wherein said quenching treatment is normal temperature water quenching.
8. A method of improving the fatigue performance of a high strength aluminum alloy according to claim 1, wherein said aging treatment is natural aging.
9. A torsion device for improving fatigue performance of high-strength aluminum alloy is characterized by comprising: an aluminum bar external anti-torsion process instability deformation clamp 3 and an aluminum bar clamping and torsion device 1; the aluminum bar external clamp 3 is independent of the aluminum bar clamping and twisting device 1, and the aluminum bar external clamp 3 is fastened by bolts 4.
10. The use of the high strength aluminum alloy of claim 9 in the fields of transportation, packaging containers, architectural decoration, aerospace, mechanical and electrical, electronic communications, petrochemical, energy power, and physical and chemical hygiene.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116042987A (en) * | 2022-12-01 | 2023-05-02 | 舟山市7412工厂 | Aluminum alloy bolt grain heat treatment process |
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| US5993924A (en) * | 1996-07-30 | 1999-11-30 | Elf Atochem S. A. | Coating of metal surfaces, its application to tubes and to cables |
| CN106381458A (en) * | 2016-10-13 | 2017-02-08 | 南京工程学院 | Amorphous alloy strengthening method based on limited high-pressure torsion |
| CN108570633A (en) * | 2018-05-21 | 2018-09-25 | 江苏大学 | Improve the preparation method of 6xxx line aluminium alloy friction and wear behaviors |
| CN110241367A (en) * | 2019-07-03 | 2019-09-17 | 吉林大学 | A kind of aluminium alloy method for toughening based on pulse current |
| CN111349767A (en) * | 2018-12-20 | 2020-06-30 | 波音公司 | High-pressure torsion device and method for changing material properties of workpiece by using same |
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2020
- 2020-12-21 CN CN202011520347.0A patent/CN112725711B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5993924A (en) * | 1996-07-30 | 1999-11-30 | Elf Atochem S. A. | Coating of metal surfaces, its application to tubes and to cables |
| CN106381458A (en) * | 2016-10-13 | 2017-02-08 | 南京工程学院 | Amorphous alloy strengthening method based on limited high-pressure torsion |
| CN108570633A (en) * | 2018-05-21 | 2018-09-25 | 江苏大学 | Improve the preparation method of 6xxx line aluminium alloy friction and wear behaviors |
| CN111349767A (en) * | 2018-12-20 | 2020-06-30 | 波音公司 | High-pressure torsion device and method for changing material properties of workpiece by using same |
| CN110241367A (en) * | 2019-07-03 | 2019-09-17 | 吉林大学 | A kind of aluminium alloy method for toughening based on pulse current |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116042987A (en) * | 2022-12-01 | 2023-05-02 | 舟山市7412工厂 | Aluminum alloy bolt grain heat treatment process |
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