7-series aluminum alloy wire and method of making

Abstract

The application relates to the field of aluminum alloys, and discloses a 7-series aluminum alloy wire and a preparation method thereof. In order to improve the service life of a welding joint of the 7-series aluminum alloy wire, after an element Hf is added into the 7-series aluminum alloy wire, the hardness of the welding joint can be improved; along with the increase of the amount of the element Hf, the hardness of the welding joint first increases and then tends to be stable. However, the tensile strength of the aluminum alloy wire presents a trend of first increasing and then decreasing, and excessive element Hf can cause the tensile strength of the 7-series aluminum alloy wire to deteriorate, therefore, the element Hf needs to be controlled in 0.35-2.25 parts by weight.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloys, and more specifically to a 7-series aluminum alloy wire and its preparation method. Background Technology

[0002] 7-series aluminum alloys, including Al-Zn-Mg and Al-Zn-Mg-Cu alloys, were invented by German scientists in the 1920s. These high-strength aluminum alloys are currently primarily used in structural components and represent one of the future directions for lightweight engineering. The application of 7-series aluminum alloys in welding has garnered significant attention. However, insufficient hardness in welded joints severely impacts the material's service life; therefore, it is necessary to improve the hardness of 7-series aluminum alloy welded joints. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing 7-series aluminum alloy wire, which can produce weld joints with excellent hardness.

[0004] The technical solution of the present invention is as follows:

[0005] A method for preparing 7-series aluminum alloy wire includes the following steps:

[0006] 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 an electric resistance furnace and heated to melt at a temperature of 735-750℃. Then, the mixture is held at this temperature for 4-6 hours under electromagnetic stirring at 300-350 r / min. After filtering the molten metal, it is cast to obtain 7-series aluminum alloy ingots.

[0007] The 7-series aluminum alloy ingots are homogenized by holding them at 472-480℃ for 5.5-6 hours, then heating them to 558-560℃ and holding them for 24-28 hours, followed by water cooling.

[0008] The homogenized 7-series aluminum alloy ingots were subjected to extrusion. The extrusion process conditions were: extrusion temperature 440-450℃, extrusion speed 32-35m / min, extrusion ratio 23.5-25.0, and extrusion wire diameter 6.5-7.2mm.

[0009] The extruded 7-series aluminum alloy is drawn, and after 10 drawing processes, 7-series aluminum alloy wire with a diameter of 1.5-1.8 mm is obtained.

[0010] Preferably, the melting temperature is 735°C.

[0011] Preferably, the extrusion temperature is 440°C.

[0012] Preferably, the extrusion speed is 32 m / min.

[0013] Preferably, the extrusion ratio is 23.5.

[0014] Preferably, the diameter of the 7-series aluminum alloy wire is 1.5 mm.

[0015] Furthermore, the present invention also provides a 7-series aluminum alloy wire, which is prepared by the above method.

[0016] To improve the service life of welded joints made of 7-series aluminum alloy wire, this invention adds Hf to the 7-series aluminum alloy wire, which increases the hardness of the welded joint. With increasing Hf content, the hardness of the welded joint initially increases and then stabilizes. However, the tensile strength of the aluminum alloy wire exhibits a trend of initially increasing and then decreasing. Excessive Hf can lead to a deterioration in the tensile strength of the 7-series aluminum alloy wire. Therefore, the Hf content needs to be controlled between 0.35-2.25 parts by weight. The process conditions for welding the 7-series aluminum alloy wire 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 welded joint is greater than 68HV. Detailed Implementation

[0017] The technical effects of the present invention will be verified through specific embodiments below, but the implementation of the present invention is not limited thereto.

[0018] Example 1

[0019] 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 an electric resistance furnace and heated to melt at a melting temperature of 735℃. The mixture was then held at 300 r / min for 6 h under electromagnetic stirring. After filtering the molten metal, it was cast to obtain 7-series aluminum alloy ingots.

[0020] The 7-series aluminum alloy ingots were homogenized by holding them at 472℃ for 5.5 hours, then heating them to 558℃ and holding them for 28 hours, followed by water cooling.

[0021] The homogenized 7-series aluminum alloy ingots were extruded. The extrusion process conditions were: extrusion temperature 440℃, extrusion speed 32m / min, extrusion ratio 23.5, and extrusion wire diameter 6.5mm.

[0022] The extruded 7-series aluminum alloy was drawn, and after 10 drawing processes, 7-series aluminum alloy wire with a diameter of 1.5 mm was obtained.

[0023] Example 2

[0024] 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 an electric resistance furnace and heated to melt at a melting temperature of 735℃. The mixture was then held at 300 r / min for 6 h under electromagnetic stirring. After filtering the molten metal, it was cast to obtain 7-series aluminum alloy ingots.

[0025] The 7-series aluminum alloy ingots were homogenized by holding them at 472℃ for 5.5 hours, then heating them to 558℃ and holding them for 28 hours, followed by water cooling.

[0026] The homogenized 7-series aluminum alloy ingots were extruded. The extrusion process conditions were: extrusion temperature 440℃, extrusion speed 32m / min, extrusion ratio 23.5, and extrusion wire diameter 6.5mm.

[0027] The extruded 7-series aluminum alloy was drawn, and after 10 drawing processes, 7-series aluminum alloy wire with a diameter of 1.5 mm was obtained.

[0028] Example 3

[0029] 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 an electric resistance furnace and heated to melt at a melting temperature of 735℃. The mixture was then held at 300 r / min for 6 h under electromagnetic stirring. After filtering the molten metal, it was cast to obtain 7-series aluminum alloy ingots.

[0030] The 7-series aluminum alloy ingots were homogenized by holding them at 472℃ for 5.5 hours, then heating them to 558℃ and holding them for 28 hours, followed by water cooling.

[0031] The homogenized 7-series aluminum alloy ingots were extruded. The extrusion process conditions were: extrusion temperature 440℃, extrusion speed 32m / min, extrusion ratio 23.5, and extrusion wire diameter 6.5mm.

[0032] The extruded 7-series aluminum alloy was drawn, and after 10 drawing processes, 7-series aluminum alloy wire with a diameter of 1.5 mm was obtained.

[0033] Example 4

[0034] 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 an electric resistance furnace and heated to melt at a melting temperature of 735℃. The mixture was then held at 300 r / min for 6 h under electromagnetic stirring. After filtering the molten metal, it was cast to obtain 7-series aluminum alloy ingots.

[0035] The 7-series aluminum alloy ingots were homogenized by holding them at 472℃ for 5.5 hours, then heating them to 558℃ and holding them for 28 hours, followed by water cooling.

[0036] The homogenized 7-series aluminum alloy ingots were extruded. The extrusion process conditions were: extrusion temperature 440℃, extrusion speed 32m / min, extrusion ratio 23.5, and extrusion wire diameter 6.5mm.

[0037] The extruded 7-series aluminum alloy was drawn, and after 10 drawing processes, 7-series aluminum alloy wire with a diameter of 1.5 mm was obtained.

[0038] Example 5

[0039] 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 an electric resistance furnace and heated to melt at a melting temperature of 735℃. The mixture was then held at 300 r / min for 6 h under electromagnetic stirring. After filtering the molten metal, it was cast to obtain 7-series aluminum alloy ingots.

[0040] The 7-series aluminum alloy ingots were homogenized by holding them at 472℃ for 5.5 hours, then heating them to 558℃ and holding them for 28 hours, followed by water cooling.

[0041] The homogenized 7-series aluminum alloy ingots were extruded. The extrusion process conditions were: extrusion temperature 440℃, extrusion speed 32m / min, extrusion ratio 23.5, and extrusion wire diameter 6.5mm.

[0042] The extruded 7-series aluminum alloy was drawn, and after 10 drawing processes, 7-series aluminum alloy wire with a diameter of 1.5 mm was obtained.

[0043] Comparative Example 1

[0044] 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 an electric resistance furnace and heated to melt at a temperature of 735°C. The mixture was then held at 300 r / min for 6 hours under electromagnetic stirring. After filtering the molten metal, it was cast to obtain 7-series aluminum alloy ingots.

[0045] The 7-series aluminum alloy ingots were homogenized by holding them at 472℃ for 5.5 hours, then heating them to 558℃ and holding them for 28 hours, followed by water cooling.

[0046] The homogenized 7-series aluminum alloy ingots were extruded. The extrusion process conditions were: extrusion temperature 440℃, extrusion speed 32m / min, extrusion ratio 23.5, and extrusion wire diameter 6.5mm.

[0047] The extruded 7-series aluminum alloy was drawn, and after 10 drawing processes, 7-series aluminum alloy wire with a diameter of 1.5 mm was obtained.

[0048] Comparative Example 2

[0049] 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 an electric resistance furnace and heated to melt at a melting temperature of 735℃. The mixture was then held at 300 r / min for 6 h under electromagnetic stirring. After filtering the molten metal, it was cast to obtain 7-series aluminum alloy ingots.

[0050] The 7-series aluminum alloy ingots were homogenized by holding them at 472℃ for 5.5 hours, then heating them to 558℃ and holding them for 28 hours, followed by water cooling.

[0051] The homogenized 7-series aluminum alloy ingots were extruded. The extrusion process conditions were: extrusion temperature 440℃, extrusion speed 32m / min, extrusion ratio 23.5, and extrusion wire diameter 6.5mm.

[0052] The extruded 7-series aluminum alloy was drawn, and after 10 drawing processes, 7-series aluminum alloy wire with a diameter of 1.5 mm was obtained.

[0053] Next, we evaluated the tensile strength of the experimental samples in Examples 1-5 and Comparative Examples 1-2, and performed welding using a welding machine. The welding process conditions were: current 125A, voltage 22V, wire feed speed 8.5mm / s, and welding speed 230mm / min. The microhardness of the welded joint was then tested. To ensure the comparability of the tests, all process conditions were identical except for the 7-series aluminum alloy wire. The test results are shown in Table 1.

[0054] Table 1 Test data for each sample

[0055]

[0056] As shown in Table 1, adding Hf to 7-series aluminum alloy wire can improve the hardness of the welded joint. With the increase of Hf content, the hardness of the welded 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 Hf will lead to the deterioration of the tensile strength of 7-series aluminum alloy wire. Therefore, it is necessary to control Hf within the range of 0.35-2.25 parts by weight.

[0057] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing 7-series aluminum alloy wire for welded joints, characterized in that, The method includes 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 1.27-2.25 parts by weight of Hf are placed in an electric resistance furnace and heated to melt at a temperature of 735-750℃. Then, the temperature is maintained for 4-6 hours under electromagnetic stirring at 300-350 r / min. After filtering the molten metal, it is cast to obtain 7-series aluminum alloy ingots. The 7-series aluminum alloy ingots are homogenized by holding them at 472-480℃ for 5.5-6 hours, then heating them to 558-560℃ and holding them for 24-28 hours, followed by water cooling. The homogenized 7-series aluminum alloy ingots were subjected to extrusion. The extrusion process conditions were: extrusion temperature 440-450℃, extrusion speed 32-35m / min, extrusion ratio 23.5-25.0, and extrusion wire diameter 6.5-7.2mm. The extruded 7-series aluminum alloy is drawn through 10 drawing passes to obtain 7-series aluminum alloy wire with a diameter of 1.5-1.8 mm. The tensile strength of the 7-series aluminum alloy wire is greater than 385 MPa, and the microhardness of the welded joint is greater than 68 HV.

2. The method as described in claim 1, characterized in that, The melting temperature is 735℃.

3. The method as described in claim 1, characterized in that, The extrusion temperature is 440°C.

4. The method as described in claim 1, characterized in that, The extrusion speed is 32 m / min.

5. The method as described in claim 1, characterized in that, The extrusion ratio is 23.

5.

6. The method as described in 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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