7-series aluminum alloy wire and preparation method thereof

Abstract

The invention relates to the field of aluminum alloy, and discloses a 7-series aluminum alloy wire and a preparation method thereof. In order to prolong the service life of the 7-series aluminum alloy wire welded joint, after the element Hf is added into the 7-series aluminum alloy wire, the hardness of the welded joint can be improved, and the hardness of the welded joint is firstly increased and then tends to be stable along with the increase of the use amount of the element Hf. However, the tensile strength of the aluminum alloy wire is in a trend of firstly increasing and then decreasing, and the excessive element Hf can cause deterioration of the tensile strength of the 7-series aluminum alloy wire, so that the element Hf needs to be controlled to be 0.35-2.25 parts by weight.

Description

Technical Field

[0001] The present invention relates to the field of aluminum alloys, and in particular to a 7 series aluminum alloy wire and a preparation method thereof. Background Art

[0002] 7-series aluminum alloys, which can be divided into Al-Zn-Mg and Al-Zn-Mg-Cu alloys, were invented by German scientists in the 1920s. They are high-strength aluminum alloys and are currently primarily used in structural components, representing a future trend in lightweight engineering. The application of 7-series aluminum alloys in welding has garnered widespread attention. However, insufficient hardness of welded joints severely impacts the material's service life. Therefore, it is necessary to increase the hardness of 7-series aluminum alloy welded joints. Summary of the Invention

[0003] The object of the present invention is to provide a method for preparing a 7 series aluminum alloy wire, wherein the aluminum alloy wire prepared by the method can obtain a welded joint with excellent hardness.

[0004] The technical solutions of the present invention are as follows: A method for preparing a 7 series aluminum alloy wire comprises the following steps: Based on 100 parts by weight of Al, 6.3-8.0 parts by weight of Zn, 0.85-1.20 parts by weight of Mg, 0.25-0.40 parts by weight of Cu, 0.3-0.5 parts by weight of Fe, 0.15-0.32 parts by weight of Si, and 0.35-2.25 parts by weight of Hf are placed in a resistance furnace and heated and melted at a melting temperature of 735-750°C, and then kept warm for 4-6 hours under electromagnetic stirring at 300-350 r / min, and then the molten metal is filtered through a filter and cast to obtain a 7 series aluminum alloy ingot; The 7 series aluminum alloy ingot is homogenized by holding it at 472-480°C for 5.5-6 hours, then heating it to 558-560°C and holding it for 24-28 hours, followed by water cooling. The homogenized 7 series aluminum alloy ingot is extruded under the following process conditions: extrusion temperature 440-450°C, extrusion speed 32-35 m / min, extrusion ratio 23.5-25.0, and extruded wire billet diameter 6.5-7.2 mm. The extruded 7 series aluminum alloy is subjected to a drawing process, and after 10 drawing processes, a 7 series aluminum alloy wire with a diameter of 1.5-1.8 mm is obtained.

[0005] Preferably, the smelting temperature is 735°C.

[0006] Preferably, the extrusion temperature is 440°C.

[0007] Preferably, the extrusion speed is 32 m / min.

[0008] Preferably, the extrusion ratio is 23.5.

[0009] Preferably, the diameter of the 7 series aluminum alloy wire is 1.5 mm.

[0010] Furthermore, the present invention also provides a 7 series aluminum alloy wire, which is prepared by the above method.

[0011] In order to improve the service life of the 7-series aluminum alloy wire welding joint, the present invention adds the element Hf to the 7-series aluminum alloy wire to improve the hardness of the welding joint. As the amount of element Hf increases, the hardness of the welding joint first increases and then tends to stabilize. However, the tensile strength of the aluminum alloy wire shows a trend of first increasing and then decreasing. Excessive element Hf will cause the tensile strength of the 7-series aluminum alloy wire to deteriorate. Therefore, it is necessary to control the element Hf to 0.35-2.25 parts by weight. Among them, the process conditions for using the 7-series aluminum alloy wire for welding are: current 125-130A, voltage 22-25V, wire feed speed 8.5-9.2mm / s, and welding speed 230-260mm / min. The tensile strength of the 7-series aluminum alloy wire is greater than 385MPa, and the microhardness of the welding joint is greater than 68HV. DETAILED DESCRIPTION

[0012] The technical effects of the present invention are verified below through specific examples, but the embodiments of the present invention are not limited thereto.

[0013] Example 1 Based on 100 parts by weight of Al, 6.3 parts by weight of Zn, 0.85 parts by weight of Mg, 0.25 parts by weight of Cu, 0.3 parts by weight of Fe, 0.15 parts by weight of Si, and 0.35 parts by weight of Hf were placed in a resistance furnace for heating and melting at a melting temperature of 735°C, and then kept warm for 6 hours under electromagnetic stirring at 300 r / min. The molten metal was then filtered through a filter and cast to obtain a 7 series aluminum alloy ingot; The 7 series aluminum alloy ingot was homogenized by holding it at 472°C for 5.5 hours, then heating it to 558°C and holding it for 28 hours, followed by water cooling. The homogenized 7 series aluminum alloy ingot was extruded under the following process conditions: extrusion temperature 440°C, extrusion speed 32 m / min, extrusion ratio 23.5, and extruded wire billet diameter 6.5 mm. The extruded 7 series aluminum alloy is subjected to a drawing process, and after 10 drawing processes, a 7 series aluminum alloy wire with a diameter of 1.5 mm is obtained.

[0014] Example 2 Based on 100 parts by weight of Al, 6.3 parts by weight of Zn, 0.85 parts by weight of Mg, 0.25 parts by weight of Cu, 0.3 parts by weight of Fe, 0.15 parts by weight of Si, and 0.80 parts by weight of Hf were placed in a resistance furnace for heating and melting at a melting temperature of 735°C, and then kept warm for 6 hours under electromagnetic stirring at 300 r / min. The molten metal was then filtered through a filter and cast to obtain a 7 series aluminum alloy ingot; The 7 series aluminum alloy ingot was homogenized by holding it at 472°C for 5.5 hours, then heating it to 558°C and holding it for 28 hours, followed by water cooling. The homogenized 7 series aluminum alloy ingot was extruded under the following process conditions: extrusion temperature 440°C, extrusion speed 32 m / min, extrusion ratio 23.5, and extruded wire billet diameter 6.5 mm. The extruded 7 series aluminum alloy is subjected to a drawing process, and after 10 drawing processes, a 7 series aluminum alloy wire with a diameter of 1.5 mm is obtained.

[0015] Example 3 Based on 100 parts by weight of Al, 6.3 parts by weight of Zn, 0.85 parts by weight of Mg, 0.25 parts by weight of Cu, 0.3 parts by weight of Fe, 0.15 parts by weight of Si, and 1.27 parts by weight of Hf were placed in a resistance furnace and heated and melted at a melting temperature of 735°C. The mixture was then kept warm for 6 hours under electromagnetic stirring at 300 r / min. The molten metal was then filtered through a filter and cast to obtain a 7 series aluminum alloy ingot. The 7 series aluminum alloy ingot was homogenized by holding it at 472°C for 5.5 hours, then heating it to 558°C and holding it for 28 hours, followed by water cooling. The homogenized 7 series aluminum alloy ingot was extruded under the following process conditions: extrusion temperature 440°C, extrusion speed 32 m / min, extrusion ratio 23.5, and extruded wire billet diameter 6.5 mm. The extruded 7 series aluminum alloy is subjected to a drawing process, and after 10 drawing processes, a 7 series aluminum alloy wire with a diameter of 1.5 mm is obtained.

[0016] Example 4 Based on 100 parts by weight of Al, 6.3 parts by weight of Zn, 0.85 parts by weight of Mg, 0.25 parts by weight of Cu, 0.3 parts by weight of Fe, 0.15 parts by weight of Si, and 1.70 parts by weight of Hf were placed in a resistance furnace for heating and melting at a melting temperature of 735°C, and then kept warm for 6 hours under electromagnetic stirring at 300 r / min. The molten metal was then filtered through a filter and cast to obtain a 7 series aluminum alloy ingot; The 7 series aluminum alloy ingot was homogenized by holding it at 472°C for 5.5 hours, then heating it to 558°C and holding it for 28 hours, followed by water cooling. The homogenized 7 series aluminum alloy ingot was extruded under the following process conditions: extrusion temperature 440°C, extrusion speed 32 m / min, extrusion ratio 23.5, and extruded wire billet diameter 6.5 mm. The extruded 7 series aluminum alloy is subjected to a drawing process, and after 10 drawing processes, a 7 series aluminum alloy wire with a diameter of 1.5 mm is obtained.

[0017] Example 5 Based on 100 parts by weight of Al, 6.3 parts by weight of Zn, 0.85 parts by weight of Mg, 0.25 parts by weight of Cu, 0.3 parts by weight of Fe, 0.15 parts by weight of Si, and 2.25 parts by weight of Hf were placed in a resistance furnace for heating and melting at a melting temperature of 735°C, and then kept warm for 6 hours under electromagnetic stirring at 300 r / min. The molten metal was then filtered through a filter and cast to obtain a 7 series aluminum alloy ingot; The 7 series aluminum alloy ingot was homogenized by holding it at 472°C for 5.5 hours, then heating it to 558°C and holding it for 28 hours, followed by water cooling. The homogenized 7 series aluminum alloy ingot was extruded under the following process conditions: extrusion temperature 440°C, extrusion speed 32 m / min, extrusion ratio 23.5, and extruded wire billet diameter 6.5 mm. The extruded 7 series aluminum alloy is subjected to a drawing process, and after 10 drawing processes, a 7 series aluminum alloy wire with a diameter of 1.5 mm is obtained.

[0018] Comparative Example 1 Based on 100 parts by weight of Al, 6.3 parts by weight of Zn, 0.85 parts by weight of Mg, 0.25 parts by weight of Cu, 0.3 parts by weight of Fe, and 0.15 parts by weight of Si were placed in a resistance furnace and heated and melted at a melting temperature of 735°C. The mixture was then kept warm for 6 hours under electromagnetic stirring at 300 r / min. The molten metal was then filtered through a filter and cast to obtain a 7 series aluminum alloy ingot. The 7 series aluminum alloy ingot was homogenized by holding it at 472°C for 5.5 hours, then heating it to 558°C and holding it for 28 hours, followed by water cooling. The homogenized 7 series aluminum alloy ingot was extruded under the following process conditions: extrusion temperature 440°C, extrusion speed 32 m / min, extrusion ratio 23.5, and extruded wire billet diameter 6.5 mm. The extruded 7 series aluminum alloy is subjected to a drawing process, and after 10 drawing processes, a 7 series aluminum alloy wire with a diameter of 1.5 mm is obtained.

[0019] Comparative Example 2 Based on 100 parts by weight of Al, 6.3 parts by weight of Zn, 0.85 parts by weight of Mg, 0.25 parts by weight of Cu, 0.3 parts by weight of Fe, 0.15 parts by weight of Si, and 4.0 parts by weight of Hf were placed in a resistance furnace and heated and melted at a melting temperature of 735°C. The mixture was then kept warm for 6 hours under electromagnetic stirring at 300 r / min. The molten metal was then filtered through a filter and cast to obtain a 7 series aluminum alloy ingot. The 7 series aluminum alloy ingot was homogenized by holding it at 472°C for 5.5 hours, then heating it to 558°C and holding it for 28 hours, followed by water cooling. The homogenized 7 series aluminum alloy ingot was extruded under the following process conditions: extrusion temperature 440°C, extrusion speed 32 m / min, extrusion ratio 23.5, and extruded wire billet diameter 6.5 mm. The extruded 7 series aluminum alloy is subjected to a drawing process, and after 10 drawing processes, a 7 series aluminum alloy wire with a diameter of 1.5 mm is obtained.

[0020] Next, we evaluated the tensile strength of the samples from Examples 1-5 and Comparative Examples 1-2. Welding was performed using a welding machine using the following process conditions: current 125A, voltage 22V, wire feed speed 8.5mm / s, and welding speed 230mm / min. The microhardness of the welded joints was then measured. To ensure comparability between the test groups, all process conditions were identical except for the 7-series aluminum alloy wire. The test results are shown in Table 1.

[0021] Table 1 Test data of each sample As shown in Table 1, adding Hf to 7-series aluminum alloy wire improves weld joint hardness. With increasing Hf content, the weld joint hardness initially increases and then levels off. However, the tensile strength of the aluminum alloy wire initially increases and then decreases. Excessive Hf can deteriorate the tensile strength of 7-series aluminum alloy wire. Therefore, the Hf content should be controlled within a range of 0.35-2.25 parts by weight.

[0022] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a 7 series aluminum alloy wire, characterized in that: The method comprises the following steps: Based on 100 parts by weight of Al, 6.3-8.0 parts by weight of Zn, 0.85-1.20 parts by weight of Mg, 0.25-0.40 parts by weight of Cu, 0.3-0.5 parts by weight of Fe, 0.15-0.32 parts by weight of Si, and 0.35-2.25 parts by weight of Hf are placed in a resistance furnace and heated and melted at a melting temperature of 735-750°C, and then kept warm for 4-6 hours under electromagnetic stirring at 300-350 r / min, and then the molten metal is filtered through a filter and cast to obtain a 7 series aluminum alloy ingot; The 7 series aluminum alloy ingot is homogenized by holding it at 472-480°C for 5.5-6 hours, then heating it to 558-560°C and holding it for 24-28 hours, followed by water cooling. The homogenized 7 series aluminum alloy ingot is extruded under the following process conditions: extrusion temperature 440-450°C, extrusion speed 32-35 m / min, extrusion ratio 23.5-25.0, and extruded wire billet diameter 6.5-7.2 mm. The extruded 7 series aluminum alloy is subjected to a drawing process, and after 10 drawing processes, a 7 series aluminum alloy wire with a diameter of 1.5-1.8 mm is obtained.

2. A method according to claim 1, characterized in that The smelting temperature is 735°C.

3. A method according to claim 1, characterized in that The extrusion temperature is 440°C.

4. A method according to claim 1, characterized in that The extrusion speed is 32 m / min.

5. A method according to claim 1, characterized in that The extrusion ratio is 23.

5.

6. A method according to claim 1, characterized in that The diameter of the 7 series aluminum alloy wire is 1.5 mm.

7. A 7 series aluminum alloy wire, characterized in that: The 7 series aluminum alloy wire is prepared by any one of the methods described in claims 1-6.

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