High-toughness aluminum alloy bolt and method for manufacturing the same

Abstract

The application relates to the technical field of bolts, and discloses a high-toughness aluminum alloy bolt and a preparation method thereof.The high-toughness aluminum alloy bolt is composed of the following components in percentage by weight: Si 7-8%, Mg 0.30-0.4%, Cu 0.8-1.2%, Mn 0.4-0.6%, Ti 0.15-0.2%, Zr 0.12-0.15%, Cr 0.05-0.15%, B 0.01-0.02%, the balance of Al and inevitable impurities, and Si / Mg=17.5-27.The above technical scheme solves the problem of low toughness of the aluminum alloy bolt in the related art.

Description

Technical Field

[0001] This invention relates to the field of bolt technology, specifically to a high-toughness aluminum alloy bolt and its preparation method. Background Technology

[0002] With the rapid development of aerospace, rail transportation, new energy vehicles, and high-end equipment manufacturing towards lightweight, high strength, and high reliability, traditional steel bolts, due to their heavy weight and susceptibility to corrosion, can no longer meet the core requirements of equipment miniaturization and energy saving. Aluminum alloy bolts, with their outstanding advantages such as low density, high specific strength, excellent corrosion resistance, and good thermal and electrical conductivity, are gradually replacing steel bolts and becoming key connecting components in lightweight equipment.

[0003] Aluminum alloy bolts are often used in complex stress environments, requiring excellent impact toughness to withstand impact loads, vibration loads, and stress impacts from temperature fluctuations, preventing brittle fracture and ensuring equipment safety. However, current aluminum alloy bolts generally suffer from insufficient toughness.

[0004] Therefore, it is necessary to propose a high-toughness aluminum alloy bolt and its preparation method. Summary of the Invention

[0005] This invention proposes a high-toughness aluminum alloy bolt and its preparation method, which solves the problem of low toughness of aluminum alloy bolts in related technologies.

[0006] The technical solution of the present invention is as follows: This invention proposes a high-toughness aluminum alloy bolt, which, by weight percentage, is composed of the following components: Si 7%~8%, Mg 0.30%~0.4%, Cu 0.8%~1.2%, Mn 0.4%~0.6%, Ti 0.15%~0.2%, Zr 0.12%~0.15%, Cr 0.05%~0.15%, B 0.01%~0.02%, with the balance being Al and unavoidable impurities, and Si / Mg = 17.5~27.

[0007] As a further technical solution, the Ti, Zr, Cr and B, by weight percentage, satisfy the relationship: (Ti+Zr+Cr) / B=21~42, preferably 28.

[0008] As a further technical solution, the Zr and Cr satisfy the relationship Zr / Cr = 1~2.4, preferably 1.4, by weight percentage.

[0009] This invention also proposes a method for preparing high-toughness aluminum alloy bolts, comprising the following steps: S1. The bolt blank is obtained by batching, melting, casting, cooling and molding according to the weight percentage of the bolt components. S2. The bolt blank is subjected to homogenization treatment, solution treatment, water quenching, and aging treatment to obtain a semi-finished bolt. S3. Perform thread processing on the semi-finished bolts to obtain high-toughness aluminum alloy bolts.

[0010] As a further technical solution, in step S2, the homogenization process is as follows: first, a primary homogenization process is performed at 420~440℃ for 4~6 hours, followed by a secondary homogenization process at 480~500℃ for 8~10 hours, and then the temperature is raised to 520~540℃ for a tertiary homogenization process for 12~16 hours.

[0011] This invention employs a three-stage homogenization process, which avoids the grain coarsening problem caused by single-stage high-temperature homogenization. The first-stage homogenization occurs at a lower temperature, which slowly releases casting stress while preventing premature grain coarsening. The second-stage homogenization achieves deep homogenization, dissolving coarse and brittle phases in the microstructure. The third-stage homogenization involves holding the material at a higher temperature for a longer period, further improving microstructure uniformity. The synergistic effect of the specific alloy composition of this invention with the aforementioned three-stage homogenization process enables aluminum alloy bolts to achieve excellent impact toughness.

[0012] As a further technical solution, the heating rate from the end of the first homogenization treatment to the temperature of the second homogenization treatment and the heating rate from the end of the second homogenization treatment to the temperature of the third homogenization treatment are each independently 20~30℃ / h.

[0013] As a further technical solution, in step S2, the solution treatment is carried out at 460~480℃ for 2~3 hours.

[0014] As a further technical solution, in step S2, the water temperature during water quenching is 25~35℃, and the water quenching time is 20~25s.

[0015] As a further technical solution, in step S2, the aging treatment is to first keep the temperature at 150~160℃ for 10 hours, and then raise the temperature to 170~180℃ and keep it for 5 hours.

[0016] As a further technical solution, in step S1, argon gas is introduced for protection during the melting process, and the argon gas flow rate is 0.3~0.5L / min.

[0017] The working principle and beneficial effects of this invention are as follows: In this invention, the Si / Mg ratio in the aluminum alloy bolts is controlled to be 17.5~27 to avoid the formation of a large amount of brittle and hard Mg2Si phase, thus reducing the number of brittle crack initiation sites within the material. Simultaneously, the use of a composite of Ti, Zr, Cr, and B refines the grains, effectively increasing crack propagation resistance and improving the impact toughness of the aluminum alloy bolts. The addition of Mn reduces stress concentration, further enhancing the impact toughness. Through the synergistic effect of these elements, the impact toughness of the aluminum alloy bolts is improved, solving the problem of low impact toughness in aluminum alloy bolts. The resulting aluminum alloy bolts can improve the safety of equipment operation. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1 A method for preparing a high-toughness aluminum alloy bolt includes the following steps: S1. Prepare the bolt blank by mixing, melting (argon gas is introduced for protection during the process, and the argon gas flow rate is 0.3L / min) according to the weight percentage of the bolts in Table 1, casting, cooling and forming. S2. The bolt blank is first heated to 420℃ at a rate of 20℃ / h for primary homogenization treatment for 4h, then heated to 480℃ at a rate of 20℃ / h for secondary homogenization treatment for 10h, then heated to 520℃ at a rate of 20℃ / h for tertiary homogenization treatment for 16h, then held at 460℃ for 3h for solution treatment, then immediately quenched in water at 25℃ for 25s, then air-cooled to room temperature, first held at 150℃ for 10h, then heated to 170℃ for 5h for aging treatment, and finally cooled to room temperature to obtain a semi-finished bolt. S3. The semi-finished bolts are threaded to obtain high-toughness aluminum alloy bolts.

[0020] Example 2 A method for preparing a high-toughness aluminum alloy bolt includes the following steps: S1. Prepare the bolt blank by mixing, melting (using argon gas for protection during the process, with an argon gas flow rate of 0.5 L / min), casting, cooling, and molding according to the bolt weight percentage in Table 1. S2. The bolt blank is first heated to 440℃ at a rate of 30℃ / h for primary homogenization treatment for 4 hours, then heated to 500℃ at a rate of 30℃ / h for secondary homogenization treatment for 8 hours, then heated to 540℃ at a rate of 30℃ / h for tertiary homogenization treatment for 12 hours, then held at 480℃ for 2 hours for solution treatment, then immediately transferred to 35℃ water for quenching for 20 seconds, then air-cooled to room temperature, first held at 160℃ for 10 hours, then heated to 180℃ for 5 hours for aging treatment, to obtain semi-finished bolts. S3. The semi-finished bolts are threaded to obtain high-toughness aluminum alloy bolts.

[0021] Example 3 A method for preparing a high-toughness aluminum alloy bolt includes the following steps: S1. Prepare the bolt blank by mixing, melting (using argon gas for protection during the process, with an argon gas flow rate of 0.3~0.5L / min) according to the weight percentage of the bolts in Table 1, casting, cooling and forming. S2. The bolt blank is heated to 430℃ at a rate of 25℃ / h for primary homogenization treatment for 5 hours, then heated to 490℃ at a rate of 25℃ / h for secondary homogenization treatment for 9 hours, then heated to 530℃ at a rate of 25℃ / h for tertiary homogenization treatment for 14 hours, then held at 470℃ for 2.5 hours for solution treatment, then immediately quenched in water at 30℃ for 23 seconds, then air-cooled to room temperature, first held at 155℃ for 10 hours, then heated to 175℃ for 5 hours for aging treatment, to obtain semi-finished bolts; S3. The semi-finished bolts are threaded to obtain high-toughness aluminum alloy bolts.

[0022] Example 4 In this embodiment, the composition of the bolt by weight percentage is shown in Table 1, and the preparation method of the high-toughness aluminum alloy bolt is the same as that in Example 2.

[0023] Example 5 In this embodiment, the composition of the bolt by weight percentage is shown in Table 1, and the preparation method of the high-toughness aluminum alloy bolt is the same as that in Example 2.

[0024] Example 6 In this embodiment, the composition of the bolt by weight percentage is shown in Table 1, and the preparation method of the high-toughness aluminum alloy bolt is the same as that in Example 2.

[0025] Example 7 In this embodiment, the composition of the bolt by weight percentage is shown in Table 1, and the preparation method of the high-toughness aluminum alloy bolt is the same as that in Example 2.

[0026] Example 8 In this embodiment, the composition of the bolt by weight percentage is shown in Table 1, and the preparation method of the high-toughness aluminum alloy bolt is the same as that in Example 2.

[0027] Example 9 In this embodiment, the composition of the bolt by weight percentage is shown in Table 1, and the preparation method of the high-toughness aluminum alloy bolt is the same as that in Example 2.

[0028] Example 10 A method for preparing a high-toughness aluminum alloy bolt includes the following steps: S1. Prepare the bolt blank by mixing, melting (using argon gas for protection during the process, with an argon gas flow rate of 0.5 L / min), casting, cooling, and molding according to the bolt weight percentage in Table 1. S2. The bolt blank is first heated to 500℃ at a rate of 30℃ / h for primary homogenization treatment for 10h, then heated to 540℃ at a rate of 30℃ / h for secondary homogenization treatment for 14h, then held at 480℃ for 2h for solution treatment, then immediately transferred to 35℃ water for 20s for water quenching, then air cooled to room temperature, first held at 160℃ for 10h, then heated to 180℃ for 5h for aging treatment, to obtain semi-finished bolts; S3. The semi-finished bolts are threaded to obtain high-toughness aluminum alloy bolts.

[0029] Example 11 A method for preparing a high-toughness aluminum alloy bolt includes the following steps: S1. Prepare the bolt blank by mixing, melting (using argon gas for protection during the process, with an argon gas flow rate of 0.5 L / min), casting, cooling, and molding according to the bolt weight percentage in Table 1. S2. After heating the bolt blank to 500℃ at a rate of 30℃ / h for secondary homogenization treatment for 24h, it is then kept at 480℃ for 2h for solution treatment. Immediately afterward, it is quenched in water at 35℃ for 20s and then air-cooled to room temperature. It is then kept at 160℃ for 10h and then heated to 180℃ for 5h for aging treatment to obtain semi-finished bolts. S3. The semi-finished bolts are threaded to obtain high-toughness aluminum alloy bolts.

[0030] Example 12 A method for preparing a high-toughness aluminum alloy bolt includes the following steps: S1. Prepare the bolt blank by mixing, melting (using argon gas for protection during the process, with an argon gas flow rate of 0.5 L / min), casting, cooling, and molding according to the bolt weight percentage in Table 1. S2. The bolt blank is first heated to 440℃ at a rate of 30℃ / h for primary homogenization treatment for 4 hours, then heated to 500℃ at a rate of 30℃ / h for secondary homogenization treatment for 10 hours, then heated to 540℃ at a rate of 30℃ / h for tertiary homogenization treatment for 10 hours, then held at 480℃ for 2 hours for solution treatment, then immediately transferred to 35℃ water for quenching for 20 seconds, then air-cooled to room temperature, first held at 160℃ for 10 hours, then heated to 180℃ for 5 hours for aging treatment, to obtain semi-finished bolts. S3. The semi-finished bolts are threaded to obtain high-toughness aluminum alloy bolts.

[0031] Comparative Example 1 In this comparative example, the composition of the bolts by weight percentage is shown in Table 1, and the preparation method of the high-toughness aluminum alloy bolts is the same as that in Example 1.

[0032] Comparative Example 2 In this comparative example, the composition of the bolts by weight percentage is shown in Table 1, and the preparation method of the high-toughness aluminum alloy bolts is the same as that in Example 1.

[0033] Comparative Example 3 In this comparative example, the composition of the bolts by weight percentage is shown in Table 1, and the preparation method of the high-toughness aluminum alloy bolts is the same as that in Example 1.

[0034] Table 1. Components of bolt raw materials in Examples 1-9 and Comparative Examples 1-3

[0035] The components in Table 1 satisfy the relationships shown in Table 2 below, and the values ​​are rounded to one decimal place.

[0036] Table 2 Summary of Relationships in Examples 1-9

[0037] Experimental Example Impact toughness tests were conducted on the high-toughness aluminum alloy bolts in Examples 1-12 and 1-3, according to the determination method in GB / T 229-2020 "Metallic Materials Charpy Pendulum Impact Test Method". During the test, the sample length was 55mm, the cross-section was a 10mm×10mm square section with a V-shaped notch in the middle, and the radius of curvature of the pendulum hammer edge was 2mm. The results are shown in Table 3.

[0038] Table 3 Performance Test Results

[0039] According to the performance test results in Table 3, the impact toughness of the aluminum alloy bolts in Examples 1-12 is greater than that in Comparative Examples 1-3, which proves that the composition of the aluminum alloy bolts in this invention can improve the impact toughness of the aluminum alloy bolts.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-toughness aluminum alloy bolt, characterized in that, It consists of the following components by weight percentage: Si 7%~8%, Mg 0.30%~0.4%, Cu 0.8%~1.2%, Mn 0.4%~0.6%, Ti 0.15%~0.2%, Zr 0.12%~0.15%, Cr 0.05%~0.15%, B 0.01%~0.02%, with the balance being Al and unavoidable impurities, and Si / Mg = 17.5~27.

2. The high-toughness aluminum alloy bolt according to claim 1, characterized in that, By weight percentage, the Ti, Zr, Cr and B satisfy the following relationship: (Ti+Zr+Cr) / B=21~42.

3. The high-toughness aluminum alloy bolt according to claim 2, characterized in that, By weight percentage, the Zr and Cr satisfy the relationship: Zr / Cr = 1~2.

4.

4. A method for preparing a high-toughness aluminum alloy bolt, used to prepare the high-toughness aluminum alloy bolt according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. The bolt blank is obtained by batching, melting, casting, cooling and molding according to the weight percentage of the bolt components. S2. The bolt blank is subjected to homogenization treatment, solution treatment, water quenching, and aging treatment to obtain a semi-finished bolt. S3. Perform thread processing on the semi-finished bolts to obtain high-toughness aluminum alloy bolts.

5. The method for preparing a high-toughness aluminum alloy bolt according to claim 4, characterized in that, In step S2, the homogenization process involves first performing a primary homogenization process at 420-440℃ for 4-6 hours, then performing a secondary homogenization process at 480-500℃ for 8-10 hours, and finally raising the temperature to 520-540℃ for a tertiary homogenization process for 12-16 hours.

6. The method for preparing a high-toughness aluminum alloy bolt according to claim 5, characterized in that, The heating rate from the end of the first homogenization treatment to the temperature of the second homogenization treatment and the heating rate from the end of the second homogenization treatment to the temperature of the third homogenization treatment are each 20~30℃ / h independently.

7. The method for preparing a high-toughness aluminum alloy bolt according to claim 4, characterized in that, In step S2, the solution treatment is performed by holding the solution at 460~480℃ for 2~3 hours.

8. The method for preparing a high-toughness aluminum alloy bolt according to claim 4, characterized in that, In step S2, the water temperature during water quenching is 25~35℃, and the water quenching time is 20~25s.

9. The method for preparing a high-toughness aluminum alloy bolt according to claim 4, characterized in that, In step S2, the aging process involves first holding the temperature at 150~160℃ for 10 hours, and then raising the temperature to 170~180℃ and holding it for 5 hours.

10. The method for preparing a high-toughness aluminum alloy bolt according to claim 4, characterized in that, In step S1, argon gas is introduced for protection during the melting process, and the argon gas flow rate is 0.3~0.5L / min.

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