High-strength corrosion-resistant Sb-containing aluminum alloy and plate preparation method thereof

Abstract

The invention discloses a high-strength corrosion-resistant Sb-containing aluminum alloy and a plate preparation method thereof, and belongs to the technical field of aluminum alloy material performance research. The method comprises the following steps: smelting and alloying: smelting high-purity Al as a matrix to 700-750 DEG C, and sequentially adding Zn, Mg and Cu; keeping the temperature, and adding 0.3 wt% of Sc and 0.2 wt% of Zr into the melt; 0.1 wt%-0.5 wt% of Sb element is added for microalloying, and uniform stirring is carried out; casting the melt into a cast ingot, and cooling to room temperature; carrying out homogenizing annealing on the cast ingot; and carrying out hot rolling or room-temperature cold rolling processing to obtain the required thickness and plate shape. According to the invention, Sb microalloying is innovatively combined with Sc and Zr modification to form a synergistic effect of grain refinement, precipitation optimization and corrosion resistance improvement. And clear guidance of the optimal Sb addition amount (0.4 wt.%) is provided, and the problem that system research and optimization are lacked in the prior art is solved.

Description

Technical Field

[0001] This invention belongs to the technical field of aluminum alloy material performance research, specifically relating to a high-strength, corrosion-resistant Sb-containing aluminum alloy and its sheet preparation method. The resulting aluminum alloy material is used in aerospace and ship structural components. Background Technology

[0002] 7xxx series aluminum alloys (represented by Al-Zn-Mg-Cu) are widely used in the manufacture of structural components for aerospace, shipbuilding, and high-end transportation equipment due to their high specific strength and good wear resistance. However, these alloys have insufficient corrosion resistance under high-strength conditions, and are particularly prone to stress corrosion cracking (SCC) and exfoliation corrosion in marine environments, which seriously affects their service life.

[0003] Existing research indicates that adding trace amounts of Sc and Zr to Al-Zn-Mg-Cu alloys can form a dispersed Al3(Sc,Zr) phase within the matrix, refining the grains and inhibiting recrystallization, thereby improving the alloy's strength and thermal stability. However, even with the addition of Sc and Zr, the improvement in corrosion resistance of 7xxx series alloys in highly corrosive environments remains limited, especially at the cost of strength, which is a significant drawback in engineering applications.

[0004] In recent years, microalloying technology has been used to further improve the overall properties of alloys. Studies have shown that antimony (Sb) in aluminum alloys can affect the morphology and distribution of precipitated phases, improve grain boundary structure, and enhance the stability of corrosion films. However, there are currently few studies on the addition of trace amounts of Sb to Al-Zn-Mg-Cu-Sc-Zr alloys, especially lacking a systematic exploration of the effects of different Sb contents on the mechanical properties and corrosion resistance of the alloys in the as-cast and rolled states.

[0005] In summary, existing technologies mainly suffer from the following problems: high-strength 7xxx series aluminum alloys exhibit insufficient corrosion resistance in highly corrosive environments such as marine environments; while Sc and Zr modification can improve microstructural stability, their effect on corrosion resistance is limited; and there is a lack of systematic research and optimization of the optimal addition amount for Sb microalloying in Al-Zn-Mg-Cu-Sc-Zr alloys. Therefore, there is an urgent need to develop a method for preparing Al-Zn-Mg-Cu-Sc-Zr alloys that significantly improves corrosion resistance while maintaining high strength, in order to meet the demand for lightweight, corrosion-resistant structural materials in high-end equipment. Summary of the Invention

[0006] This invention aims to address the insufficient corrosion resistance of existing high-strength 7xxx series (Al-Zn-Mg-Cu) aluminum alloys in highly corrosive environments such as marine environments. Simultaneously, it aims to improve the corrosion resistance and microstructural stability of the alloys while maintaining their high strength. Furthermore, addressing the lack of systematic research on the addition of trace amounts of antimony (Sb) to Al-Zn-Mg-Cu-Sc-Zr alloys, this invention explores and optimizes the influence of different Sb contents on the mechanical and corrosion resistance of as-cast and rolled alloys. This results in a method for improving the mechanical and corrosion resistance of aluminum alloys through Sb microalloying, and the development of Sb-microalloyed aluminum alloys. This solves the problems of insufficient corrosion resistance and limited microstructural stability in high-strength 7xxx series aluminum alloys, and optimizes their mechanical properties and corrosion resistance in both as-cast and rolled states.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a high-strength, corrosion-resistant Sb-containing aluminum alloy sheet, the method comprising:

[0009] Step 1: Melting and Alloying: High-purity Al is melted to 700℃~750℃ (preferably 750℃) as the matrix. Zn, Mg, and Cu are added sequentially to form an Al-Zn-Mg-Cu matrix. While maintaining the temperature, 0.3wt% Sc and 0.2wt% Zr are added to the melt to form an Al-Zn-Mg-Cu-Sc-Zr matrix alloy. For microalloying, 0.1wt%~0.5wt% Sb is added and stirred evenly to ensure uniform element distribution. The mass percentage indicates the mass percentage of the added element relative to the total content.

[0010] Step 2: Casting and heat treatment: The melt is poured into ingots and cooled to room temperature; the ingots are subjected to homogenization annealing to optimize the alloy structure and reduce compositional segregation;

[0011] Step 3: Rolling: The homogenized annealed ingot is hot rolled or room temperature cold rolled to obtain the required thickness and plate shape; the deformation and dislocations introduced by rolling are beneficial to the improvement of mechanical properties.

[0012] This invention achieves a synergistic effect of grain refinement, precipitate optimization, and improved corrosion resistance by first adding Sc and Zr to form a stable matrix, followed by Sb microalloying. Sc and Zr serve as grain refinement and microstructure stabilization elements, while Sb acts as a microalloying element to improve the morphology of precipitates and enhance corrosion resistance. Optimization of the Sb content (0.4 wt.%) optimizes both the mechanical properties and corrosion resistance of the cast and rolled alloys.

[0013] Furthermore, in step one, the content of the four elements in the Al-Zn-Mg-Cu matrix is ​​determined according to the range specified in the national standard for 7-series aluminum alloys.

[0014] Furthermore, in step two, the annealing temperature is determined based on the peak value of the DSC test.

[0015] Furthermore, in step two, the annealing temperature is 400℃~475℃, and the time is 0.5~1.5 h.

[0016] Furthermore, in step three, the temperature of the hot-rolled rolls is 100~300℃.

[0017] A high-strength, corrosion-resistant Sb-containing aluminum alloy obtained by the above method, wherein the aluminum alloy is based on an Al-Zn-Mg-Cu alloy and contains the following alloying elements: 0.3wt% Sc, 0.2wt% Zr, and 0.1wt%~0.5wt% Sb.

[0018] This invention achieves a significant improvement in mechanical properties and corrosion resistance by microalloying Sb in Al-Zn-Mg-Cu-Sc-Zr alloys, and has the following advantages and characteristics:

[0019] (1) Improved mechanical properties: By forming stable dispersed phases with Sc and Zr and improving the distribution of precipitated phases with Sb, grain refinement and microstructure homogenization are achieved, thereby enhancing the strength and toughness of the alloy. The tensile strength and yield strength of the cast and rolled alloys are significantly improved. Compared with the Al-Zn-Mg-Cu-Sc-Zr matrix alloy without Sb, the tensile strength of the cast alloy is increased by about 10% and the yield strength is increased by about 8%. The tensile strength of the rolled alloy is increased by about 19% and the yield strength is increased by about 25%.

[0020] (2) Enhanced corrosion resistance: Sb microalloying improves the stability of the corrosion film at the interface between the matrix and the precipitated phase, significantly reducing the corrosion rate of the cast and rolled alloys in simulated seawater or salt spray environments. The alloy exhibits the best corrosion resistance when the Sb content is 0.4 wt.%, achieving a balance between high strength and corrosion resistance.

[0021] (3) Advantages in process and material costs: By adding trace elements, no additional complex chemical treatment or metallurgical modification process is required. The operation is simple and easy to promote in existing 7xxx series aluminum alloy production lines. The amount of Sb added is low (≤0.5 wt.%), which saves raw material costs and avoids negative impacts on melt fluidity and processing performance.

[0022] (4) Comprehensive performance optimization: The preparation method provided by the present invention improves corrosion resistance while ensuring high strength, and achieves a balance of performance in the cast and rolled states. It is suitable for applications such as aerospace, shipbuilding and high-end transportation equipment that require lightweight, high-strength and corrosion-resistant structural materials.

[0023] This invention innovatively combines Sb microalloying with Sc and Zr modification to achieve a synergistic effect of grain refinement, precipitation optimization, and improved corrosion resistance. It also provides clear guidance on the optimal Sb addition amount (0.4 wt.%), addressing the lack of systematic research and optimization in existing technologies. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0025] Microalloying refers to the technique of adding trace alloying elements (such as Sb, Sc, and Zr) at a mass fraction of less than 1% to an alloy to significantly improve its microstructure and overall properties.

[0026] Example 1:

[0027] Raw material preparation: High-purity aluminum (Al, purity ≥99.9%) as the matrix; Master alloy: 5% Zn, 2.5% Mg, 0.5 Cu added according to the target alloy composition ratio; Trace elements: Sc, Zr, Sb;

[0028] Step 1: Melting and Alloying: Melt high-purity Al to 720~750℃, maintaining a homogeneous liquid phase; sequentially add Zn, Mg, and Cu master alloys, stirring until homogeneous to form an Al-Zn-Mg-Cu matrix; add 0.3wt% Sc and 0.2wt% Zr to the melt, stirring thoroughly until homogeneous; add 0.1wt.% Sb, stirring to ensure uniform element distribution; dissolve each metal for 8~12 minutes, then stir with a graphite rod for 15~30 seconds.

[0029] Step 2: Casting and Annealing: The melt is poured into an ingot and cooled to room temperature; the ingot is annealed (temperature can be selected from 400℃ to 475℃, time is 1 hour) to facilitate subsequent deformation treatment;

[0030] Step 3: Rolling process: The homogenized annealed ingot is warm rolled at 200℃ to obtain a plate or the required shape; during the rolling process, the temperature of the rolls and the deformation thickness of each roll (the deformation amount is 1mm each time) are ensured to obtain the required thickness and uniform structure.

[0031] Example 2: This example differs from Example 1 in that the amount of Sb added is 0.2wt%.

[0032] Example 3: This example differs from Example 1 in that the amount of Sb added is 0.3 wt%.

[0033] Example 4: This example differs from Example 1 in that the amount of Sb added is 0.4 wt%.

[0034] Example 5: This example differs from Example 1 in that the amount of Sb added is 0.5 wt%.

[0035] Performance Testing and Verification: Tensile and corrosion resistance tests were conducted on the as-cast and rolled samples of Examples 1-5, respectively. For the as-cast samples, the cast metal was directly fabricated into tensile specimens for testing. For the rolled samples, the metal was deformed by rolling before being fabricated into tensile specimens for testing. The performance results are shown in the table below: When the Sb content was 0.4 wt.%, both tensile strength and yield strength were significantly improved, while the corrosion rate decreased, resulting in the best overall performance.

[0036] As-cast state:

[0037] Tensile property test data of alloys with different Sb contents:

[0038]

[0039] Electrochemical testing

[0040] Polarization data

[0041]

[0042] Impedance data

[0043]

[0044] Rolled state:

[0045] Tensile property test data:

[0046]

[0047] Electrochemical testing

[0048] Polarization data:

[0049]

[0050] Impedance data:

[0051]

[0052] Example 6:

[0053] Raw material preparation: High-purity aluminum (Al, purity ≥99.9%) as the matrix; Master alloy: Zn, Mg, Cu added according to the target alloy composition ratio; Trace elements: Sc, Zr, Sb;

[0054] Step 1: Melting and Alloying: Melt high-purity Al to 700~720℃, maintaining a homogeneous liquid phase; sequentially add Zn, Mg, and Cu master alloys, stirring until homogeneous to form an Al-Zn-Mg-Cu matrix; add 0.3wt% Sc and 0.2wt% Zr to the melt, stirring thoroughly until homogeneous; add 0.2wt.% Sb, stirring to ensure uniform element distribution; dissolve each metal for 8~12 minutes, then stir with a graphite rod for 20~30 seconds.

[0055] Step 2: Casting and Annealing: The melt is poured into an ingot and cooled to room temperature; the ingot is annealed (temperature can be selected from 400℃ to 475℃, time is 1 hour) to facilitate subsequent deformation treatment;

[0056] Step 3: Rolling process: The homogenized annealed ingot is cold rolled at room temperature to obtain a plate or the required shape; during the rolling process, the temperature of the rolls and the deformation thickness of each roll (the deformation amount is 1 mm each time) are ensured to obtain the required thickness and uniform structure.

[0057] Application scenario example 1:

[0058] The material obtained in Example 6, when used in marine environments such as ship decks and structural supports, can significantly improve service life. This material is also suitable for applications requiring lightweight, high-strength materials, such as aerospace components.

[0059] Example 7:

[0060] Raw material preparation: High-purity aluminum (Al, purity ≥99.9%) as the matrix; Master alloy: Zn, Mg, Cu added according to the target alloy composition ratio; Trace elements: Sc, Zr, Sb;

[0061] Step 1: Melting and Alloying: Melt high-purity Al to 720~750℃, maintaining a homogeneous liquid phase; sequentially add Zn, Mg, and Cu master alloys, stirring until homogeneous to form an Al-Zn-Mg-Cu matrix; add 0.3wt% Sc and 0.2wt% Zr to the melt, stirring thoroughly until homogeneous; add 0.3wt.% Sb, stirring to ensure uniform element distribution; dissolve each metal for 8~10 minutes, then stir with a graphite rod for 25~30 seconds.

[0062] Step 2: Casting and Annealing: The melt is poured into an ingot and cooled to room temperature; the ingot is annealed (temperature can be selected from 450℃ to 475℃, time is 1 hour) to facilitate subsequent deformation treatment;

[0063] Step 3: Rolling process: The homogenized annealed ingot is warm rolled at 250℃ to obtain a plate or the required shape; during the rolling process, the temperature of the rolls and the deformation thickness of each rolling (the deformation amount is 1mm each time) are ensured to obtain the required thickness and uniform structure.

[0064] Example 8:

[0065] The Sb addition amount can be adjusted within the range of 0.35~0.45 wt.%, depending on the specific application environment, to balance mechanical properties and corrosion resistance. Even small variations in Sb content during microalloying can lead to significant microscopic changes due to the limiting solid solubility. Exceeding the limiting solid solubility will result in coarse, irregular particles, thus affecting performance.

[0066] Rolling temperature and deformation can be optimized: By adjusting the hot rolling temperature (100~200℃) and deformation rate, the grains can be further refined, and the strength and toughness can be improved.

Claims

1. A method for preparing a high-strength, corrosion-resistant Sb-containing aluminum alloy sheet, characterized in that: The method is as follows: Step 1: Melting and Alloying: High-purity Al is melted to 700℃~750℃ as the matrix, and Zn, Mg, and Cu are added sequentially to form an Al-Zn-Mg-Cu matrix; while maintaining the temperature, 0.3wt% Sc and 0.2wt% Zr are added to the melt to form an Al-Zn-Mg-Cu-Sc-Zr matrix alloy; for microalloying, 0.1wt%~0.5wt% Sb element is added and stirred evenly; Step 2: Casting and heat treatment: The melt is poured into ingots and cooled to room temperature; the ingots are subjected to homogenization annealing to optimize the alloy structure and reduce compositional segregation; Step 3: Rolling process: The homogenized annealed ingot is hot rolled or cold rolled to obtain the required thickness and plate shape.

2. The method for preparing a high-strength, corrosion-resistant Sb-containing aluminum alloy plate according to claim 1, characterized in that: In step one, the content of the four elements in the Al-Zn-Mg-Cu matrix is ​​determined according to the range specified in the national standard for 7-series aluminum alloys.

3. The method for preparing a high-strength, corrosion-resistant Sb-containing aluminum alloy plate according to claim 1, characterized in that: In step two, the annealing temperature is determined based on the peak value of the DSC test.

4. A method for preparing a high-strength, corrosion-resistant Sb-containing aluminum alloy plate according to claim 1 or 3, characterized in that: In step two, the annealing temperature is 400℃~475℃ and the time is 0.5~1.5 h.

5. The method for preparing a high-strength, corrosion-resistant Sb-containing aluminum alloy plate according to claim 1, characterized in that: In step three, the temperature of the hot rolling rolls is 100~300℃.

6. A high-strength, corrosion-resistant Sb-containing aluminum alloy obtained by the method according to any one of claims 1 to 5, characterized in that: The aluminum alloy is based on an Al-Zn-Mg-Cu alloy and contains the following alloying elements: 0.3wt% Sc, 0.2wt% Zr, and 0.1wt%~0.5wt% Sb.

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