A solid solution and artificial aging preparation method of a new type of 7-series aluminum alloy and the new type of 7-series aluminum alloy

Abstract

The application discloses a solid solution and artificial aging preparation method of a novel 7-series aluminum alloy and the novel 7-series aluminum alloy, and belongs to the field of aluminum alloy heat treatment. The method comprises the following steps: (1) preparing a natural aging state 7-series aluminum alloy; (2) performing solid solution treatment on the natural aging state 7-series aluminum alloy, wherein the solid solution temperature is 470-520 DEG C, and the holding time is 10-30 min; and (3) performing artificial aging treatment on the 7-series aluminum alloy after the solid solution treatment, wherein the aging temperature is 140-170 DEG C, and the holding time is 8-12 h. Through the solid solution treatment, the soluble strengthening phase in the alloy is dissolved into the aluminum matrix, and the excess solute atoms are retained in the aluminum matrix to form a supersaturated solid solution; and then through the artificial aging treatment, the supersaturated solute atoms are precipitated in the form of dispersed distribution of precipitated phase particles, so that the strength of the aluminum alloy after the solid solution treatment and the artificial aging treatment is improved, and the plasticity of the aluminum alloy is ensured.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy heat treatment technology, specifically to a novel method for preparing 7-series aluminum alloys through solution treatment and artificial aging, and to the novel 7-series aluminum alloy itself. Background Technology

[0002] Aluminum alloys are widely used in shipbuilding, construction, machinery manufacturing, and the automotive industry. Replacing steel with lightweight aluminum alloys is increasingly valued across industries, representing an inevitable trend in lightweighting. Aluminum alloy products possess high specific strength, good corrosion resistance, and weldability, and are used in automotive engines, bodies, chassis, wheels, and flanges. They exhibit excellent mechanical properties and strong stability, and are gradually replacing high-strength steel products in more automotive structural components. Replacing steel components with aluminum alloy components can reduce the overall weight of a vehicle by 30-40%. Therefore, the application of aluminum alloys in the automotive field has strong application prospects and sustainable competitiveness. The new 7-series aluminum alloys belong to the Al-Mg-Zn-Cu system, possessing excellent strength, good toughness, and moderate corrosion resistance, and can be strengthened through different heat treatment processes. Different elements have complex effects on the mechanical properties of the new 7-series aluminum alloys. Cu helps increase the number of precipitated phases, lowers the precipitation temperature of strengthening phases, and improves the mechanical properties of the alloy; however, high Cu content increases the alloy's corrosion susceptibility. Mg promotes the nucleation and formation of the MgZn2 phase, which is the main intermetallic compound for age hardening of the alloy. Sc and Zr form thermally stable Al3(Sc,Zr) core-shell particles, exhibiting strong dispersion strengthening and recrystallization inhibition capabilities, significantly improving strength, fatigue resistance, heat resistance, and weldability. Ti and B form tiny heterogeneous nucleation cores such as TiB2 or Al3Ti during casting, which play a role in the solidification stage, transforming coarse cast columnar crystals into fine equiaxed crystals, thereby significantly reducing casting cracks, improving material deformation and processing properties, and resulting in more uniform properties in the final product.

[0003] Al-Mg-Zn-Cu series 7-series aluminum alloys possess very high ultimate tensile strength. However, this high strength is accompanied by relatively low elongation at break. One method to modify the mechanical properties of these 7-series aluminum alloys is to employ appropriate heat treatment processes. Summary of the Invention

[0004] To address the problem of difficulty in improving the strength and maintaining good plasticity of 7-series aluminum alloys in existing technologies, the present invention aims to provide a novel method for preparing 7-series aluminum alloys through solution treatment and artificial aging, and a novel 7-series aluminum alloy. By combining specific solution treatment with artificial aging treatment, the fine and dispersed precipitates in the resulting aluminum alloy can effectively hinder the movement of dislocations within the crystal, thereby improving the strength of the aluminum alloy. At the same time, the small size of the precipitates can alleviate stress concentration during deformation, thereby ensuring the plasticity of the alloy.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A novel method for preparing 7-series aluminum alloys through solution treatment and artificial aging includes the following steps: (1) Prepare naturally aged 7-series aluminum alloys; (2) Solution treatment: The naturally aged 7 series aluminum alloy is subjected to solution treatment so that the soluble strengthening phase in the aluminum alloy dissolves into the aluminum matrix to obtain the solution-treated 7 series aluminum alloy. (3) Artificial aging treatment: The solution-treated 7 series aluminum alloy is subjected to artificial aging treatment so that the supersaturated solute atoms in the 7 series aluminum alloy precipitate in the form of dispersed precipitate particles, and a new type of 7 series aluminum alloy is obtained.

[0006] Further, in step (1), the chemical composition of the naturally aged 7 series aluminum alloy, by weight percentage, is: Mg: 0.7-1.2wt%, Zn: 6-8wt%, Mn: 1-1.4wt%, Cu: 0.5-0.8wt%, Sc: 0.2-0.5wt%, Zr: 0.2-0.5wt%, Ti: 0.25-0.35wt%, B: 0.08-0.15wt%, with aluminum as the balance.

[0007] Furthermore, in step (2), during the solution treatment process, the solution temperature is 470-520℃ (preferably 475-520℃), and the holding time is 10-30min.

[0008] Furthermore, in step (2) during the solution treatment process, the furnace is heated during the heating process, and the heating rate is 60-70℃ / min; water cooling is used during the cooling process.

[0009] Furthermore, in step (3), during the artificial aging process, the aging temperature is 140-170℃ (preferably 145-165℃), and the temperature is maintained for 8-12 hours.

[0010] Furthermore, in step (3), during the artificial aging process, the heating is carried out by furnace heating with a heating rate of 1-2℃ / min; the cooling is carried out by furnace cooling with a cooling rate of ≥8℃ / min.

[0011] Furthermore, a novel 7-series aluminum alloy was prepared using the above method. In this novel 7-series aluminum alloy, the precipitated phases include MgZn2 phase and Al3(Sc, Zr).

[0012] Furthermore, this new 7-series aluminum alloy has a tensile strength of 320-365 MPa and an elongation of 20-34% at room temperature.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. This invention provides a method for solution treatment and artificial aging of a novel 7-series aluminum alloy. First, a naturally aged 7-series aluminum alloy is solution treated to dissolve the soluble strengthening phase in the alloy into the aluminum matrix, resulting in a solution-treated 7-series aluminum alloy. Then, artificial aging is performed to precipitate supersaturated solute atoms as dispersed precipitate particles, yielding an artificially aged novel 7-series aluminum alloy. Based on this method, solution treatment dissolves the alloying elements in the aluminum alloy and introduces them into the aluminum matrix, forming a metastable, homogeneous supersaturated solid solution. Artificial aging promotes the formation of fine, dense nucleation sites for the precipitates and causes supersaturated solute atoms to precipitate as dispersed precipitate particles. These fine, dispersed precipitates effectively hinder dislocation movement within the crystal, thereby increasing the strength of the aluminum alloy. Simultaneously, the small size of the precipitates alleviates stress concentration during deformation, ensuring the alloy's plasticity.

[0014] 2. The novel 7-series aluminum alloy prepared by this invention has a tensile strength of 320-365 MPa and an elongation of 20-34% at room temperature.

[0015] 3. Compared with the traditional solution treatment and aging method, the aluminum alloy after solution treatment and artificial aging in this invention has improved strength and hardness to a certain extent, while the required heat treatment time is greatly reduced. Attached Figure Description

[0016] Figure 1 The diagram shows the precipitate microstructure of the novel 7-series aluminum alloy obtained after solution treatment and artificial aging in Example 1. Figure 2 The microstructure of the precipitated phases corresponding to the novel 7-series aluminum alloy obtained after solution treatment and artificial aging in Comparative Example 1 is shown in the diagram. Figure 3 The image shows the tensile fracture morphology of the novel 7-series aluminum alloy obtained after solution treatment and artificial aging in Example 1. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0018] This invention provides a novel method for preparing 7-series aluminum alloys through solution treatment and artificial aging, comprising the following steps: (1) Prepare naturally aged 7-series aluminum alloys; (2) Solution treatment: The naturally aged 7 series aluminum alloy is subjected to solution treatment to dissolve the soluble strengthening phase in the 7 series aluminum alloy into the aluminum matrix and obtain a new 7 series aluminum alloy after solution treatment. The specific steps are as follows: The naturally aged 7 series aluminum alloy is placed in a heat treatment furnace at room temperature (cavity temperature) and heated to 470-520℃ at a heating rate of 60-70℃ / min, and held for 10-30min.

[0019] (3) Artificial aging treatment: The solution-treated 7-series aluminum alloy is subjected to artificial aging treatment so that the supersaturated solute atoms precipitate in the form of dispersed precipitate particles. The new 7-series aluminum alloy is obtained after artificial aging treatment. The specific steps are as follows: the solution-treated 7-series aluminum alloy is placed in a heat treatment furnace after water cooling, and the temperature is raised from room temperature to 140-170℃ at a heating rate of 1-2℃ / min, and held for 8-12 hours.

[0020] Based on the above method, solution treatment dissolves the alloying elements in the aluminum alloy and allows them to enter the aluminum matrix, forming a metastable, homogeneous, supersaturated solid solution. Then, artificial aging treatment promotes the formation of fine, dense nucleation sites for precipitates, and causes supersaturated solute atoms to precipitate as diffusely distributed precipitate particles. These fine, dispersed precipitates effectively hinder dislocation movement within the crystal, thereby increasing the strength of the aluminum alloy. Simultaneously, the small size of the precipitates alleviates stress concentration during deformation, ensuring the alloy's ductility.

[0021] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0022] In the examples and comparative examples, the chemical composition of the naturally aged 7 series aluminum alloy was: Mg 0.8wt%, Zn 7wt%, Mn 1.1wt%, Cu 0.6wt%, Sc 0.4wt%, Zr 0.2wt%, Ti 0.3wt%, B 0.1wt%, with aluminum as the balance. Example 1:

[0023] This embodiment provides a novel method for preparing 7-series aluminum alloys through solution treatment and artificial aging, comprising the following steps: Solution treatment: The naturally aged 7 series aluminum alloy is placed in a heat treatment furnace at room temperature (cavity temperature) and heated to 500℃ at a heating rate of 70℃ / min, and held for 25min; then cooled by water cooling.

[0024] Artificial aging treatment: After solution treatment, the 7-series aluminum alloy is placed in a heat treatment furnace after water cooling. The temperature is increased from room temperature to 145℃ at a rate of 1.5℃ / min and held for 10 hours. The alloy is then cooled in the furnace at a rate of ≥8℃ / min. After removal, a new type of 7-series aluminum alloy is obtained.

[0025] The precipitated phases of the novel 7-series aluminum alloy obtained in this embodiment were tested, and the results are as follows: Figure 1 As shown, the precipitated phases are fine and dispersed, with a diameter of only about 5 μm, and are uniformly distributed in the aluminum matrix. Judging from their morphology, the precipitated phases include MgZn2 phase and Al3(Sc, Zr). Microhardness and tensile tests were performed on the novel 7-series aluminum alloy obtained in this embodiment. The test results are shown in Table 1. It can be seen that the alloy obtained in this embodiment has excellent hardness, strength, and plasticity. The microhardness at room temperature is 125.34 HV, the tensile strength is 361.68 MPa, and the elongation is 26.29%. The fracture morphology after tensile testing is shown in Table 1. Figure 3 As shown, its dimples are small and uniform, and its fracture mode is ductile fracture. Example 2:

[0026] This comparative example provides a method for preparing 7-series aluminum alloys through solution treatment and artificial aging, including the following steps:

[0027] Solution treatment: Place the naturally aged 7 series aluminum alloy in a heat treatment furnace and heat it from room temperature to 510°C at a rate of 70°C / min, hold it for 30 minutes, and then cool it down with water.

[0028] Artificial aging treatment: After solution treatment, the 7-series aluminum alloy is placed in a heat treatment furnace after water cooling. The temperature is increased from room temperature to 160℃ at a rate of 1.5℃ / min and held for 10 hours. The alloy is then cooled in the furnace at a rate of ≥8℃ / min and removed.

[0029] Microhardness and tensile tests were performed on the 7-series aluminum alloy obtained after artificial aging treatment in this comparative example. The test results are shown in Table 1. It can be seen that the alloy obtained after artificial aging treatment in this comparative example has a microhardness of 116.81 HV, a tensile strength of 340.61 MPa, and an elongation of 24.73% at room temperature. Example 3:

[0030] This embodiment provides a novel method for preparing 7-series aluminum alloys through solution treatment and artificial aging, comprising the following steps: Solution treatment: The naturally aged 7 series aluminum alloy is placed in a heat treatment furnace at room temperature (cavity temperature) and heated to 480°C at a heating rate of 65°C / min, and held for 30 min; then cooled by water cooling.

[0031] Artificial aging treatment: After solution treatment, the 7-series aluminum alloy is placed in a heat treatment furnace after water cooling. The temperature is increased from room temperature to 160℃ at a rate of 1.5℃ / min and held for 10 hours. The alloy is then cooled in the furnace at a rate of ≥8℃ / min. After removal, a new type of 7-series aluminum alloy is obtained.

[0032] The novel 7-series aluminum alloy obtained in this embodiment was subjected to microhardness and tensile tests. The test results are shown in Table 1. It can be seen that the alloy obtained in this embodiment has good hardness, strength and plasticity. The microhardness at room temperature is 121.13 HV, the tensile strength is 348.18 MPa and the elongation is 28.18%. Comparative Example 1:

[0033] This comparative example provides a method for solution treatment and artificial aging of 7-series aluminum alloys, including the following steps: Solution treatment: Place the naturally aged 7 series aluminum alloy in a heat treatment furnace and heat it from room temperature to 525°C at a rate of 60°C / min, hold it at that temperature for 30 minutes, and then cool it down with water.

[0034] Artificial aging treatment: After solution treatment, the 7-series aluminum alloy is placed in a heat treatment furnace after water cooling. Starting from room temperature, the temperature is increased to 175°C at a rate of 1.5°C / min and held for 10 hours. The alloy is then cooled in the furnace at a rate of ≥8°C / min and removed.

[0035] The precipitates of the 7-series aluminum alloys obtained after artificial aging treatment in this comparative example are as follows: Figure 2 As shown, there are relatively few precipitated phases, and their distribution in the aluminum matrix is ​​uneven. Microhardness and tensile tests were performed on the 7-series aluminum alloy obtained after artificial aging treatment in this comparative example. The test results are shown in Table 1. It can be seen that the alloy obtained in this comparative example has lower hardness and strength than that of Example 1. At room temperature, the microhardness is 121.87 HV, the tensile strength is 301.49 MPa, and the elongation is 25.18%. Comparative Example 2:

[0036] This comparative example provides a method for preparing 7-series aluminum alloys through solution treatment and artificial aging, including the following steps: Solution treatment: Place the naturally aged 7 series aluminum alloy in a heat treatment furnace and heat it from room temperature to 460°C at a rate of 70°C / min, hold it for 10 minutes, and then cool it down with water.

[0037] Artificial aging treatment: After solution treatment, the 7-series aluminum alloy is placed in a heat treatment furnace after water cooling. Starting from room temperature, the temperature is increased to 130℃ at a rate of 1.5℃ / min and held for 10 hours. The alloy is then cooled in the furnace at a rate of ≥8℃ / min and removed.

[0038] Microhardness and tensile tests were performed on the 7-series aluminum alloy obtained after artificial aging treatment in this comparative example. The test results are shown in Table 1. It can be seen that the alloy obtained in this comparative example has poor hardness and strength. The microhardness is 103.5 HV at room temperature, the tensile strength is 310.27 MPa, and the elongation is 28.31%. Comparative Example 3:

[0039] This comparative example provides a method for preparing 7-series aluminum alloys through solution treatment and artificial aging, including the following steps: Solution treatment: Place the naturally aged 7 series aluminum alloy in a heat treatment furnace and heat it from room temperature to 465°C at a rate of 70°C / min, hold it at that temperature for 15 minutes, and then cool it down with water.

[0040] Artificial aging treatment: After solution treatment, the 7-series aluminum alloy is placed in a heat treatment furnace after water cooling. The temperature is increased from room temperature to 150°C at a rate of 1.5°C / min and held for 10 hours. The alloy is then cooled in the furnace at a rate of ≥8°C / min. The alloy is then removed from the furnace.

[0041] Microhardness and tensile tests were performed on the 7-series aluminum alloy obtained after artificial aging treatment in this comparative example. The test results are shown in Table 1. It can be seen that the alloy obtained in this comparative example has a microhardness of 100.03 HV, a tensile strength of 267.26 MPa, and an elongation of 16.11% at room temperature. Comparative Example 4:

[0042] This comparative example provides a method for preparing 7-series aluminum alloys through solution treatment and artificial aging, including the following steps: Solution treatment: Place the naturally aged 7 series aluminum alloy in a heat treatment furnace and heat it from room temperature to 490°C at a rate of 70°C / min, hold it for 30 minutes, and then cool it down with water.

[0043] Artificial aging treatment: After solution treatment, the 7-series aluminum alloy is placed in a heat treatment furnace after water cooling. Starting from room temperature, the temperature is increased to 175°C at a rate of 1.5°C / min and held for 10 hours. The alloy is then cooled in the furnace at a rate of ≥8°C / min and removed.

[0044] Microhardness and tensile tests were performed on the 7-series aluminum alloy obtained after artificial aging treatment in this comparative example. The test results are shown in Table 1. It can be seen that the alloy obtained after artificial aging treatment in this comparative example has a microhardness of 84.71 HV, a tensile strength of 230.91 MPa, and an elongation of 33.65% at room temperature. Comparative Example 5:

[0045] This embodiment provides a novel method for preparing 7-series aluminum alloys through solution treatment and artificial aging, comprising the following steps: Solution treatment: The naturally aged new 7-series aluminum alloy is placed in a heat treatment furnace at room temperature (cavity temperature) and heated to 460°C at a heating rate of 60°C / min, and held for 20 min; then cooled by water cooling.

[0046] Artificial aging treatment: After solution treatment, the 7-series aluminum alloy is placed in a heat treatment furnace after water cooling. The temperature is increased from room temperature to 150℃ at a rate of 1.5℃ / min and held for 10 hours. The alloy is then cooled in the furnace at a rate of ≥8℃ / min. After removal, a new type of 7-series aluminum alloy is obtained.

[0047] Microhardness and tensile tests were performed on the novel 7-series aluminum alloy obtained in this embodiment. The test results are shown in Table 1. It can be seen that the alloy obtained in this embodiment has poor hardness, strength and plasticity. The microhardness at room temperature is 105.18 HV, the tensile strength is 338.62 MPa and the elongation is 22.17%.

[0048] Comparative Example 6: This comparative example provides a method for preparing 7-series aluminum alloys through solution treatment and artificial aging, including the following steps: Solution treatment: Place the naturally aged 7 series aluminum alloy in a heat treatment furnace and heat it from room temperature to 525°C at a rate of 70°C / min, hold it at that temperature for 10 minutes, and then cool it down with water.

[0049] Artificial aging treatment: After solution treatment, the 7-series aluminum alloy is placed in a heat treatment furnace after water cooling. The temperature is increased from room temperature to 150°C at a rate of 1.5°C / min and held for 10 hours. The alloy is then cooled in the furnace at a rate of ≥8°C / min. The alloy is then removed from the furnace.

[0050] Microhardness and tensile tests were performed on the 7-series aluminum alloy obtained after artificial aging treatment in this comparative example. The test results are shown in Table 1. It can be seen that the alloy obtained after artificial aging treatment in this comparative example has a microhardness of 100.7 HV, a tensile strength of 199.48 MPa, and an elongation of 34.55% at room temperature. The microhardness and tensile strength of the alloys prepared in the above embodiments and comparative examples were tested, and the test results are summarized in Table 1; wherein:

[0051] Microhardness test: Using an HV-3000B microhardness tester, the loading force was 300N and the holding time was 15s.

[0052] Tensile strength test: Using an Instron 5982 electronic universal testing machine, the tensile speed was 0.6 mm / min.

[0053] Table 1 Example 1 125.34 361.68 26.29 Example 2 116.81 340.61 24.73 Example 3 121.13 348.18 28.18 Comparative Example 1 121.87 301.49 25.18 Comparative Example 2 103.5 310.27 28.31 Comparative Example 3 100.03 267.26 16.11 Comparative Example 4 84.71 230.91 33.65 Comparative Example 5 105.18 338.62 22.17 Comparative Example 6 100.7 199.48 34.55 The above description is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A novel method for preparing 7-series aluminum alloys through solution treatment and artificial aging, characterized in that: The method includes the following steps: (1) Prepare naturally aged 7-series aluminum alloys; (2) Solution treatment: The naturally aged 7 series aluminum alloy is subjected to solution treatment so that the soluble strengthening phase in the aluminum alloy dissolves into the aluminum matrix to obtain the solution-treated 7 series aluminum alloy. (3) Artificial aging treatment: The solution-treated 7 series aluminum alloy is subjected to artificial aging treatment so that the supersaturated solute atoms in the 7 series aluminum alloy precipitate in the form of dispersed precipitate particles, and a new type of 7 series aluminum alloy is obtained.

2. The method for preparing novel 7-series aluminum alloys by solution treatment and artificial aging according to claim 1, characterized in that: In step (1), the chemical composition of the naturally aged 7-series aluminum alloy, by weight percentage, is as follows: Mg: 0.7-1.2wt%, Zn: 6-8wt%, Mn: 1-1.4wt%, Cu: 0.5-0.8wt%, Sc: 0.2-0.5wt%, Zr: 0.2-0.5wt%, Ti: 0.25-0.35wt%, B: 0.08-0.15wt%, Aluminum balance.

3. The method for preparing novel 7-series aluminum alloys by solution treatment and artificial aging according to claim 1, characterized in that: In step (2), the solution treatment process is carried out at a temperature of 470-520℃ and a holding time of 10-30 minutes.

4. The method for preparing novel 7-series aluminum alloys by solution treatment and artificial aging according to claim 3, characterized in that: In step (2) during the solution treatment, the furnace is heated at a rate of 60-70℃ / min; water cooling is used for cooling.

5. The method for preparing novel 7-series aluminum alloys by solution treatment and artificial aging according to claim 1, characterized in that: In step (3), the artificial aging process is carried out at an aging temperature of 140-170℃ for 8-12 hours.

6. The method for preparing novel 7-series aluminum alloys by solution treatment and artificial aging according to claim 5, characterized in that: In step (3), during the artificial aging process, the heating is carried out by furnace heating at a rate of 1-2℃ / min; the cooling is carried out by furnace cooling at a rate of ≥8℃ / min.

7. A novel 7-series aluminum alloy prepared using the method described in any one of claims 1-6, characterized in that: In this new 7-series aluminum alloy, the precipitated phases include MgZn2 phase and Al3(Sc, Zr).

8. The novel 7-series aluminum alloy according to claim 7, characterized in that: The new 7-series aluminum alloy has a tensile strength of 320-365 MPa and an elongation of 20-34% at room temperature.

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