7075 aluminum alloy with excellent hydrogen embrittlement resistance and preparation method thereof

Abstract

The invention discloses a 7075 aluminum alloy with excellent hydrogen embrittlement resistance and a preparation method thereof.The 7075 aluminum alloy with copper-rich clusters is obtained after the 7075 aluminum alloy is subjected to multiple solution treatment, and the preparation method specifically comprises the steps that the commercial 7075 aluminum alloy is subjected to solution treatment, then the solution temperature is increased, the 7075 aluminum alloy is subjected to second-time solution treatment, and then the 7075 aluminum alloy is subjected to hydrogen embrittlement resistance; and then the solid solution temperature is further increased, third-time solid solution treatment is conducted on the 7075 aluminum alloy, and finally quenching treatment is conducted to obtain the 7075 aluminum alloy with the excellent hydrogen embrittlement resistance. The whole heat treatment process is carried out in an argon environment. According to the 7075 aluminum alloy provided by the invention, a commercial alloying component system is adopted, and a proper heat treatment process is matched, so that the heat-treated 7075 aluminum alloy with excellent hydrogen embrittlement resistance can be obtained, the tensile strength of the heat-treated 7075 aluminum alloy is 400 Mpa or above, and the elongation at break of the heat-treated 7075 aluminum alloy under the hydrogen charging condition is nearly two times that of the commercial 7075 aluminum alloy.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy preparation, and more particularly to a 7075 aluminum alloy with excellent hydrogen embrittlement resistance and a preparation method thereof. Background Art

[0002] The 7xxx series of high-strength aluminum alloys have the advantages of low density, high strength and excellent machinability, and are important structural materials in the fields of aerospace, manufacturing, transportation and mobile communications. Unfortunately, high-strength aluminum alloys are very sensitive to environmentally assisted cracking, and like most high-strength materials, they are susceptible to hydrogen embrittlement. Dissolved hydrogen atoms can easily penetrate the surface oxide layer and diffuse into various capture sites in the aluminum alloy (such as dislocations, vacancies, grain boundaries and precipitates). Hydrogen not only reduces its plasticity, but also can change the fracture mode from toughness to brittleness, which manifests itself as intergranular or transgranular quasi-cleavage fracture on a macro scale, which limits its application and development.

[0003] Today, as the aerospace industry moves toward green energy trends, people have put forward higher requirements for designing a series of new high-strength aluminum alloys that can withstand possible environmental hydrogen embrittlement. Top aircraft manufacturers are currently developing a new generation of zero-emission aircraft. The most advanced design of zero-emission aircraft includes hydrogen combustion through modified gas turbine engines of existing commercial aircraft. This design is based on the use of liquid hydrogen as a fuel to burn with oxygen. Hydrogen combustion produces a large amount of water vapor, which exposes the applied high-strength aluminum alloy to the hydrogen environment for a long time, and eventually leads to catastrophic deterioration of the mechanical properties of the aluminum alloy. At present, researchers have improved the hydrogen embrittlement resistance of aluminum alloys by means of chemical composition optimization, alloy treatment, such as aging treatment, solution treatment, pre-deformation, combination of pre-deformation and heat treatment, and surface treatment. However, these methods sometimes sacrifice their mechanical properties instead of improving their hydrogen embrittlement resistance. Therefore, it is crucial to obtain excellent hydrogen embrittlement resistance without sacrificing the mechanical properties of the 7xxx series of high-strength aluminum alloys. Summary of the invention

[0004] Based on the problems encountered in the background technology, the present invention provides a 7075 aluminum alloy with excellent hydrogen embrittlement resistance and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a method for preparing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance, comprising the following steps:

[0007] From room temperature to temperature T 1 , at temperature T 1 The commercial 7075 aluminum alloy was first solution treated under the condition of T, and then the solution temperature was raised to T2 The 7075 aluminum alloy was subjected to a second solution treatment, and then the solution temperature was further increased to T 3 The 7075 aluminum alloy is subjected to a third solid solution treatment and finally subjected to a quenching treatment to obtain a 7075 aluminum alloy with excellent hydrogen embrittlement resistance (named as heat-treated 7075 aluminum alloy). The entire heat treatment process is performed under an argon environment.

[0008] Preferably, the solution temperature T 1 The temperature is 250-500℃, the heating rate is 2-5℃ / min, and the holding time is 200-600min.

[0009] Preferably, the solution temperature T 2 The temperature is 300-600℃, the heating rate is 2-7℃ / min, and the holding time is 200-650min.

[0010] Preferably, the solution temperature T 3 The temperature is 400-700℃, the heating rate is 2-8℃ / min, and the holding time is 300-650min.

[0011] Preferably, the solution treatment in the preparation method is carried out by heating in a high-temperature tube furnace, and the heating process is carried out under an argon atmosphere.

[0012] Preferably, the 7075 alloy is a 7075 alloy containing 0-5wt% Cu.

[0013] Preferably, 7075 aluminum alloy may also be replaced by 7050 aluminum alloy, 7049 aluminum alloy and 7010 aluminum alloy.

[0014] Preferably, the 7075 aluminum alloy with excellent hydrogen embrittlement resistance prepared by the present invention contains copper-rich clusters.

[0015] Another object of the present invention is to provide a 7075 aluminum alloy having excellent hydrogen embrittlement resistance, which is prepared by the above-mentioned preparation method of the 7075 aluminum alloy.

[0016] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0017] The 7075 aluminum alloy with excellent hydrogen embrittlement resistance provided by the present invention adopts a commercial alloying component system and is equipped with a suitable heat treatment process to obtain a 7075 aluminum alloy with excellent hydrogen embrittlement resistance, with a tensile strength of more than 400Mpa, and its elongation at break under hydrogen charging conditions is nearly twice (96.6%) that of the commercial 7075 aluminum alloy. In a simulated seawater immersion experiment, it was found that the elongation at break of the heat-treated 7075 aluminum alloy was nearly twice (97.3%) that of the commercial 7075 aluminum alloy.

[0018] The strategy of using copper-rich clusters to enhance the hydrogen embrittlement resistance of commercial 7075 aluminum alloy is expected to provide important insights into how to improve the hydrogen embrittlement resistance of other high-strength metal materials (such as high-strength steel) containing trace amounts of copper. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0020] Figure 1 The stress-strain curves of the heat-treated 7075 aluminum alloy of Example 1 and the commercial 7075 aluminum alloy of Comparative Example 1 without hydrogen charging;

[0021] Figure 2 The stress-strain curves of the heat-treated 7075 aluminum alloy in Example 1 and the commercial 7075 aluminum alloy in Comparative Example 1 after hydrogen charging;

[0022] Figure 3 This is the mapping diagram of heat-treated 7075 aluminum alloy in Example 1;

[0023] Figure 4 The stress-strain curves of the heat-treated 7075 aluminum alloy in Example 1 and the commercial 7075 aluminum alloy in Comparative Example 1 in the simulated seawater corrosion experiment. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] This embodiment provides a method for preparing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance. The commercial 7075 aluminum alloy is composed of the following chemical elements in mass fraction:

[0027] Si: 0.23%, Fe: 0.31%, Cu: 1.65%, Mn: 0.22%, Mg: 2.36%, Cr: 0.24%, Zn: 0.24%, and the balance is Al and inevitable trace impurities.

[0028] The methods include:

[0029] The temperature was raised from room temperature to 450°C at a heating rate of 4°C / min and a holding time of 360min. The commercial 7075 aluminum alloy was subjected to the first solution treatment at 450°C, and then the solution temperature was raised to 475°C at a heating rate of 5°C / min and a holding time of 360min. The 7075 aluminum alloy was subjected to the second solution treatment at 475°C. The solution temperature was further raised to 500°C at a heating rate of 5°C / min and a holding time of 360min. The 7075 aluminum alloy was subjected to the third solution treatment at 500°C. Finally, a quenching treatment was performed to obtain a 7075 aluminum alloy with excellent hydrogen embrittlement resistance (named as heat-treated 7075 aluminum alloy). The entire heat treatment process was heated in an argon environment.

[0030] like Figure 1 As shown in Figure 2, in the slow tensile test, the elongation at break of the heat-treated 7075 aluminum alloy with excellent hydrogen embrittlement resistance provided by Example 1 of the present invention after hydrogen charging is nearly twice (96.6%) that of the commercial 7075 aluminum alloy.

[0031] like Figure 3 As shown, the heat-treated 7075 aluminum alloy provided in Example 1 of the present invention contains copper-rich clusters.

[0032] like Figure 4 As shown, in the seawater simulation corrosion experiment, the elongation at break of the heat-treated 7075 aluminum alloy with excellent hydrogen embrittlement resistance provided by Example 1 of the present invention in the slow tensile test is nearly twice (97.3%) that of the commercial 7075 aluminum alloy.

[0033] The above copper-rich clusters involve the anti-hydrogen embrittlement principle:

[0034] Copper-rich clusters serve as strong hydrogen capture sites. The introduction of copper-rich clusters can reduce the hydrogen content at the grain boundaries in the material and reduce hydrogen-induced brittle fracture.

[0035] Comparative Example 1

[0036] This comparative example provides a commercial 7075 aluminum alloy, which, without subsequent treatment, is composed of the following chemical elements by mass fraction:

[0037] Si: 0.23%, Fe: 0.31%, Cu: 1.65%, Mn: 0.22%, Mg: 2.36%, Cr: 0.24%, Zn: 0.24%, and the balance is Al and inevitable trace impurities.

[0038] Example 2

[0039] This embodiment provides a method for preparing a 7075 aluminum alloy resistant to hydrogen embrittlement, wherein the 7075 aluminum alloy is composed of the following chemical elements in mass fractions:

[0040] Si: 0.3%, Fe: 0.2%, Cu: 3%, Mn: 0.1%, Mg: 3%, Cr: 0.3%, Zn: 7%, and the balance is Al and inevitable trace impurities.

[0041] The methods include:

[0042] The temperature was raised from room temperature to 500°C at a heating rate of 2°C / min and a holding time of 200min. The commercial 7075 aluminum alloy was subjected to the first solution treatment at 500°C, and then the solution temperature was raised to 600°C at a heating rate of 2°C / min and a holding time of 200min. The 7075 aluminum alloy was subjected to the second solution treatment at 600°C. The solution temperature was further raised to 700°C at a heating rate of 2°C / min and a holding time of 300min. The 7075 aluminum alloy was subjected to the third solution treatment at 700°C. Finally, a quenching treatment was performed to obtain a 7075 aluminum alloy with excellent hydrogen embrittlement resistance (named as heat-treated 7075 aluminum alloy). The entire heat treatment process was heated in an argon environment.

[0043] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0044] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance, characterized in that: The following steps are involved: The temperature is raised from room temperature to temperature T1, and the commercial 7075 aluminum alloy is subjected to the first solution treatment at temperature T1. Then, the solution temperature is raised to T2, and the 7075 aluminum alloy is subjected to the second solution treatment. Then, the solution temperature is further raised to T3, and the 7075 aluminum alloy is subjected to the third solution treatment. Finally, a quenching treatment is performed to obtain a 7075 aluminum alloy with excellent hydrogen embrittlement resistance. The entire heat treatment process is performed in an argon environment.

2. The method for preparing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance according to claim 1, characterized in that: The solution temperature T1 of the first solution treatment is 250-500°C, the heating rate is 2-5°C / min, and the holding time is 200-600min.

3. The method for preparing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance according to claim 1, characterized in that: The solution temperature T2 of the second solution treatment is 300-600°C, the heating rate is 2-7°C / min, and the holding time is 200-650min.

4. The method for preparing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance according to claim 1, characterized in that: The solution temperature T3 of the third solution treatment is 400-700°C, the heating rate is 2-8°C / min, and the holding time is 300-650min.

5. The method for preparing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance according to claim 1, characterized in that: The solution treatment is carried out in a high temperature tube furnace under an argon atmosphere.

6. The method for preparing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance according to claim 1, characterized in that: The commercial 7075 alloy is a 7075 alloy containing 0-5 wt % Cu.

7. The method for preparing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance according to claim 1, characterized in that: The 7075 aluminum alloy with excellent hydrogen embrittlement resistance contains copper-rich clusters.

8. A 7075 aluminum alloy with excellent hydrogen embrittlement resistance, characterized in that: The 7075 aluminum alloy is prepared by the preparation method of any one of claims 1 to 7.

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