A 7075 aluminum alloy having excellent hydrogen embrittlement resistance and a method for manufacturing the same

Abstract

The application discloses a 7075 aluminum alloy with excellent hydrogen embrittlement resistance and a preparation method thereof. The 7075 aluminum alloy with copper cluster is obtained through multiple solid solution treatment, and specifically comprises the following steps: solid solution treatment is performed on a commercial 7075 aluminum alloy, then the 7075 aluminum alloy is subjected to second solid solution treatment by increasing the solid solution temperature, then the 7075 aluminum alloy is subjected to third solid solution treatment by further increasing the solid solution temperature, and finally quenching treatment is performed to obtain the 7075 aluminum alloy with excellent hydrogen embrittlement resistance. The whole heat treatment process is performed under heating treatment in an argon environment. The 7075 aluminum alloy provided by the application adopts a commercial alloying component system and is matched with a suitable heat treatment process, 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 above 400 Mpa, and the fracture elongation of the heat-treated 7075 aluminum alloy under hydrogen charging is nearly 2 times that of the commercial 7075 aluminum alloy.

Description

TECHNICAL FIELD

[0001] The present application 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

[0002] High-strength aluminum alloys of the 7xxx series have the advantages of low density, high strength and excellent processability, and are important structural materials in the fields of aerospace, manufacturing, transportation and mobile communication. Unfortunately, high-strength aluminum alloys are very sensitive to environmental assisted cracking, and like most high-strength materials, they are susceptible to hydrogen embrittlement, where dissolved hydrogen atoms can easily penetrate the surface oxide layer and diffuse to various trapping sites (such as dislocations, vacancies, grain boundaries and precipitates) in the aluminum alloy. Hydrogen not only reduces its plasticity, but also can change the fracture mode from ductile to brittle, which is macroscopically manifested as intergranular or transgranular quasi-cleavage fracture, which limits its application and development.

[0003] Now, with the development of the aerospace industry towards green energy, people have 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 improved gas turbine engines of existing commercial aircraft. This design is based on the use of liquid hydrogen as fuel and oxygen combustion. Hydrogen combustion produces a large amount of water vapor, which exposes the high-strength aluminum alloy used to a hydrogen environment for a long time, ultimately leading to catastrophic deterioration of the mechanical properties of the aluminum alloy. Currently, researchers have improved the hydrogen embrittlement resistance of aluminum alloys through means such as chemical composition optimization, alloy treatment, such as aging treatment, solid solution treatment, pre-deformation, a combination of pre-deformation and heat treatment, and surface treatment. However, these methods sometimes sacrifice the mechanical properties of the aluminum alloy rather than improving its hydrogen embrittlement resistance. Therefore, it is crucial to obtain excellent hydrogen embrittlement resistance without sacrificing the mechanical properties of high-strength aluminum alloys of the 7xxx series. SUMMARY

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

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] The present application provides a preparation method of a 7075 aluminum alloy with excellent hydrogen embrittlement resistance, comprising the following steps:

[0007] The first solid solution treatment is performed on the commercial 7075 aluminum alloy at room temperature to temperature T1, the second solid solution treatment is performed on the 7075 aluminum alloy by increasing the solid solution temperature to T2, the third solid solution treatment is performed on the 7075 aluminum alloy by further increasing the solid solution temperature to T3, and finally the quenching treatment is performed to obtain the 7075 aluminum alloy with excellent hydrogen embrittlement resistance (named as heat-treated 7075 aluminum alloy), and the whole heat treatment process is performed under the heating treatment in the argon atmosphere.

[0008] Preferably, the solid solution temperature T1 of the first solid solution treatment is 250-500℃, the heating rate is 2-5℃ / min, and the holding time is 200-600min.

[0009] Preferably, the solid solution temperature T2 of the second solid solution treatment is 300-600℃, the heating rate is 2-7℃ / min, and the holding time is 200-650min.

[0010] Preferably, the solid solution temperature T3 of the third solid solution treatment is 400-700℃, the heating rate is 2-8℃ / min, and the holding time is 300-650min.

[0011] Preferably, the solid solution treatment in the preparation method is performed by using the high-temperature tube furnace, and the heating process is performed in the argon atmosphere.

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

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

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

[0015] Another object of the present application is to provide a 7075 aluminum alloy with excellent hydrogen embrittlement resistance, which is prepared by the preparation method of the 7075 aluminum alloy.

[0016] According to the above technical solution, compared with the prior art, the present application has the following beneficial effects:

[0017] The application provides a 7075 aluminum alloy with excellent hydrogen embrittlement resistance, which is prepared by using a commercial alloying component system and a suitable heat treatment process, and has excellent hydrogen embrittlement resistance, a tensile strength of more than 400 MPa, and a fracture elongation that is nearly 2 times (96.6%) of that of a commercial 7075 aluminum alloy under hydrogen charging conditions. In a simulated seawater immersion corrosion experiment, it is found that the fracture elongation of the heat-treated 7075 aluminum alloy is 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 elements. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0020] Figure 1 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 Stress-strain curves of the heat-treated 7075 aluminum alloy of Example 1 and the commercial 7075 aluminum alloy of Comparative Example 1 after hydrogen charging;

[0022] Figure 3 Mapping diagram of the heat-treated 7075 aluminum alloy of Example 1;

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

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0025] Example 1

[0026] This embodiment provides a method for preparing a 7075 aluminum alloy with excellent resistance to hydrogen embrittlement. Commercially available 7075 aluminum alloy is composed of the following chemical elements by mass fraction:

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

[0028] The methods include, in sequence:

[0029] The commercial 7075 aluminum alloy was subjected to a first solution treatment at 450℃, with a heating rate of 4℃ / min and a holding time of 360min. Then, the solution treatment temperature was increased to 475℃ at a heating rate of 5℃ / min and a holding time of 360min for a second solution treatment. Next, the solution treatment temperature was further increased to 500℃ at a heating rate of 5℃ / min and a holding time of 360min for a third solution treatment. Finally, the alloy was quenched to obtain a 7075 aluminum alloy with excellent resistance to hydrogen embrittlement (named heat-treated 7075 aluminum alloy). The entire heat treatment process was carried out in an argon atmosphere.

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

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

[0032] like Figure 4 As shown, in the seawater simulated corrosion experiment, the heat-treated 7075 aluminum alloy with excellent resistance to hydrogen embrittlement provided in Example 1 of the present invention exhibited a fracture elongation rate in the slow tensile test that was nearly twice that of the commercial 7075 aluminum alloy (97.3%).

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

[0034] Copper-rich clusters serve as strong hydrogen-capturing sites. Introducing copper-rich clusters can reduce the hydrogen content at grain boundaries in materials and decrease hydrogen-induced brittle fracture.

[0035] Comparative Example 1

[0036] This comparative example provides a commercially available 7075 aluminum alloy, without any subsequent processing, 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%, the balance being Al and inevitable trace impurities.

[0038] Example 2

[0039] The embodiment provides a method for preparing a 7075 aluminum alloy resistant to hydrogen embrittlement, the 7075 aluminum alloy being composed of chemical elements with the following mass fractions:

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

[0041] The method comprises the following steps in sequence:

[0042] The commercial 7075 aluminum alloy is subjected to first solid solution treatment at 500 DEG C at a temperature rising speed of 2 DEG C / min and a holding time of 200 min, then the solid solution temperature is increased to 600 DEG C at a temperature rising speed of 2 DEG C / min, the 7075 aluminum alloy is subjected to second solid solution treatment at 600 DEG C for 200 min, then the solid solution temperature is further increased to 700 DEG C at a temperature rising speed of 2 DEG C / min, the 7075 aluminum alloy is subjected to third solid solution treatment at 700 DEG C for 300 min, and finally quenching treatment is performed to obtain the 7075 aluminum alloy (named as heat-treated 7075 aluminum alloy) with excellent hydrogen embrittlement resistance, and the whole heat treatment process is performed under heating treatment in an argon environment.

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

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

Claims

1. A method for producing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance, characterized by, The method comprises the following steps: The commercial 7075 aluminum alloy is subjected to first solution treatment at temperature T1, then second solution treatment at solution temperature T2, and third solution treatment at solution temperature T3, and finally quenching treatment to obtain the 7075 aluminum alloy with excellent hydrogen embrittlement resistance, the whole heat treatment process being carried out under argon atmosphere; The solution temperature T1 of the first solution treatment is 250-500 DEG C, the heating rate is 2-5 DEG C / min, and the holding time is 200-600 min; The solution temperature T2 of the second solution treatment is 300-600 DEG C, the heating rate is 2-7 DEG C / min, and the holding time is 200-650 min; The solution temperature T3 of the third solution treatment is 400-700 DEG C, the heating rate is 2-8 DEG C / min, and the holding time is 300-650 min.

2. The method of producing a 7075 aluminum alloy having excellent hydrogen embrittlement resistance according to claim 1, characterized by, The solution treatment is carried out by using a high-temperature tube furnace, and the heating process is carried out under argon atmosphere.

3. A 7075 aluminum alloy with excellent resistance to hydrogen embrittlement, characterized in that, The 7075 aluminum alloy is prepared by using the preparation method of claim 1 or 2. The method comprises the following steps: The commercial 7075 aluminum alloy is subjected to first solution treatment at temperature T1, then second solution treatment at solution temperature T2, and third solution treatment at solution temperature T3, and finally quenching treatment to obtain the 7075 aluminum alloy with excellent hydrogen embrittlement resistance, the whole heat treatment process being carried out under argon atmosphere; The solution temperature T1 of the first solution treatment is 250-500 DEG C, the heating rate is 2-5 DEG C / min, and the holding time is 200-600 min; The solution temperature T2 of the second solution treatment is 300-600 DEG C, the heating rate is 2-7 DEG C / min, and the holding time is 200-650 min; The solution temperature T3 of the third solution treatment is 400-700 DEG C, the heating rate is 2-8 DEG C / min, and the holding time is 300-650 min. The solution treatment is carried out by using a high-temperature tube furnace, and the heating process is carried out under argon atmosphere. The 7075 aluminum alloy is prepared by using the preparation method of claim 1 or 2.

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