A high-Cu corrosion-resistant 6-series aluminum alloy and its preparation method

Abstract

The present invention relates to the technical field of aluminum alloys, and in particular to a high-Cu corrosion-resistant 6-series aluminum alloy and a preparation method thereof, wherein the aluminum alloy comprises the following raw material components: Mg 1.0-1.03wt.%, Si 0.60-0.64wt.%, Cu 0.5-1.2wt.%, Mn≤0.12wt.%, Cr≤0.01wt.%, Ti≤0.01wt.%, Fe≤0.01wt.%, and the remainder is Al and inevitable impurities. The present invention homogenizes an aluminum alloy ingot containing the above components, extrude the homogenized material, extrudes the extruded rod temperature at 380-440°C, extrudes at a speed of 12-20 m / min, and quenches the extruded material in salt water before aging at 175-190°C for 4-12h. Through the above process control, the high-Cu 6-series aluminum alloy material has both corrosion resistance, strength and plasticity, and is suitable for fields with high requirements for the application of high-Cu 6-series aluminum alloys.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a high-Cu corrosion-resistant 6-series aluminum alloy and a preparation method thereof. Background Art

[0002] 6 series, i.e. Al-Mg-Si aluminum alloy, has high specific strength, good processing performance, welding performance and corrosion resistance, and is widely used in structural engineering industry, aviation and transportation industry. However, corrosion fatigue damage of aluminum alloy components is an important factor affecting the sustainable use of aluminum alloy.

[0003] The 6063 aluminum alloy has a low Cu content and good corrosion resistance, but low mechanical properties; the 6013 aluminum alloy has a high Cu content (0.7-1.1wt%), poor corrosion resistance, but high mechanical properties. For the 6013 aluminum alloy, the main way to improve the corrosion resistance (intergranular corrosion) is to adjust the state of the Cu-containing intergranular compounds through overaging treatment. At the same time, overaging will also reduce the mechanical properties and plasticity of the material. Therefore, it is necessary to develop a processing technology that can improve the corrosion resistance of the high-Cu 6 series aluminum alloy while ensuring the strength and plasticity of the material. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a high-Cu corrosion-resistant 6 series aluminum alloy and a preparation method thereof. The aluminum alloy has corrosion resistance, strength and high plasticity, and is suitable for fields with high requirements for the application of high-Cu 6 series aluminum alloys.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] First, the present invention provides a method for preparing a high-Cu corrosion-resistant 6-series aluminum alloy, which is carried out according to the following steps:

[0007] The following raw material components are weighed in percentage by mass: Mg 1.0-1.03wt.%, Si 0.60-0.64wt.%, Cu0.5-1.2wt.%, Mn≤0.12wt.%, Cr≤0.01wt.%, Ti≤0.01wt.%, Fe≤0.01wt.%, and the balance is Al and unavoidable impurities;

[0008] Weigh raw materials according to the mass percentage of each element in the aluminum alloy, and perform smelting and casting to obtain an ingot;

[0009] The ingot of the above composition is homogenized, kept at 500-580°C for 20-26h, and then air-cooled to room temperature;

[0010] The homogenized material is extruded, the extrusion rod temperature is 380-440°C, the extrusion speed is 12-20 m / min, and the outlet temperature is 480-530°C;

[0011] Extrusions are quenched in salt water;

[0012] The extruded material is artificially aged at 175-190℃ for 4-12h.

[0013] Further, the brine used in the brine quenching contains 2-5 wt.% NaCl.

[0014] Furthermore, the salt water also contains ≤1 wt.% KCl.

[0015] Furthermore, the temperature of the brine is 3-10°C.

[0016] Furthermore, the aluminum alloy needs to be washed with water after being quenched in salt water.

[0017] Secondly, the present invention provides a high-Cu corrosion-resistant 6-series aluminum alloy, which is prepared by the above-mentioned preparation method of the high-Cu corrosion-resistant 6-series aluminum alloy.

[0018] Furthermore, the yield strength of the high-Cu corrosion-resistant 6-series aluminum alloy is greater than 340 MPa, the tensile strength is greater than 380 MPa, and the plasticity is greater than 10%.

[0019] Since the 6 series aluminum alloy containing Cu easily forms a continuously distributed Cu compound at the grain boundary during the preparation process, the continuously distributed Cu phase is first corroded in the corrosive medium, thereby forming a grain boundary corrosion phenomenon. This phenomenon is particularly significant in high-Cu alloys, such as when the Cu content is 0.5-1.2wt.%. The present invention performs process control for the Cu content of 0.5-1.2wt.% to improve its corrosion resistance.

[0020] The present invention extrude the homogenized material, the extrusion rod temperature is 380-440°C, the extrusion speed is 12-20 m / min, and brine quenching is used. Under the condition of lower extrusion rod temperature, the material can obtain a higher extrusion speed, which can avoid the precipitation of Cu phase compounds along the grain boundaries during slow extrusion. The use of brine quenching increases the cooling intensity and further avoids the precipitation of Cu phase compounds along the crystals. The present invention particularly requires that the concentration of NaCl in the brine is 2-5wt.%, and contains no more than 1wt.% KCl. Controlling the concentration and type of salt can control the quenching speed so that the solute elements are dissolved in the matrix as soon as possible. When the water temperature is 3-10°C, the quenching speed can be further controlled, and after quenching, the surface is cleaned to remove the brine on the surface of the extruded material to avoid subsequent corrosion; finally, an aging treatment is performed at 175-190°C for 4-12h to improve the strength and plasticity of the material.

[0021] Through the above process control, the present invention can make the high-Cu 6 series aluminum alloy material have higher corrosion resistance and comprehensive properties of strength and plasticity. DETAILED DESCRIPTION

[0022] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0023] Example 1

[0024] The high Cu corrosion-resistant 6 series aluminum alloy includes, by mass percentage, Mg 1.0wt.%, Si 0.62wt.%, Cu 0.5wt.%, Mn 0.11wt.%, Cr 0.009wt.%, Ti 0.01wt.%, Fe 0.01wt.%, and the balance is Al and unavoidable impurities; raw materials are weighed according to the mass percentage of each element in the aluminum alloy, and are melted and cast to obtain an ingot;

[0025] The ingot of the above composition is homogenized, kept at 580°C for 20 hours, and then air-cooled to room temperature;

[0026] The homogenized material was extruded at an extrusion rod temperature of 380°C, an extrusion speed of 20 m / min, and an outlet temperature of 480°C, and then the extruded material was quenched with brine containing 2wt.% NaCl+1wt.% KCl at a temperature of 3°C;

[0027] The extruded material after brine quenching was washed in a clean water tank, and then artificially aged at 175°C for 12 hours.

[0028] Example 2

[0029] The high-Cu corrosion-resistant 6-series aluminum alloy includes, by mass percentage, Mg 1.03wt.%, Si 0.64wt.%, Cu 1.2wt.%, Mn 0.12wt.%, Cr 0.01wt.%, Ti 0.01wt.%, Fe 0.01wt.%, and the balance is Al and unavoidable impurities; raw materials are weighed according to the mass percentage of each element in the aluminum alloy, and are melted and cast to obtain an ingot;

[0030] The ingot of the above composition is homogenized, kept at 500°C for 26 hours, and then air-cooled to room temperature;

[0031] The homogenized material was extruded at a rod temperature of 440°C, an extrusion speed of 12 m / min, and an outlet temperature of 530°C. The extruded material was then quenched with brine containing 5wt.% NaCl+0.8wt.% KCl at a temperature of 10°C.

[0032] The extruded material after brine quenching was washed in a clean water tank, and then artificially aged at 190°C for 4 hours.

[0033] Example 3

[0034] The high-Cu corrosion-resistant 6-series aluminum alloy includes, by mass percentage, Mg 1.01wt.%, Si 0.60wt.%, Cu 0.82wt.%, Mn 0.12wt.%, Cr 0.01wt.%, Ti 0.01wt.%, Fe 0.009wt.%, and the balance is Al and unavoidable impurities; raw materials are weighed according to the mass percentage of each element in the aluminum alloy, and are melted and cast to obtain an ingot;

[0035] The ingot of the above composition was homogenized, kept at 550°C for 23h, and then air-cooled to room temperature;

[0036] The homogenized material was extruded at a rod temperature of 420°C, an extrusion speed of 18 m / min, and an outlet temperature of 500°C. The extruded material was then quenched with brine containing 3wt.% NaCl+0.6wt.% KCl at a temperature of 6°C.

[0037] The extruded material after brine quenching was washed in a clean water tank, and then artificially aged at 185°C for 9 hours.

[0038] Comparative Example 1

[0039] The aluminum alloy composition in Comparative Example 1 is consistent with that in Example 1, except that:

[0040] The homogenized material was extruded at a rod temperature of 560°C, an extrusion speed of 5 m / min, and quenched in clean water. Aging treatment was performed at 175°C for 12 h.

[0041] Comparative Example 2

[0042] The aluminum alloy composition in Comparative Example 2 is consistent with that in Example 1, except that:

[0043] The homogenized material was extruded at an extrusion rod temperature of 560°C and an extrusion speed of 5 m / min, quenched in brine containing 1 wt% NaCl at a quenching water temperature of 30°C, washed with clean water, and then subjected to aging treatment at 175°C for 12 h.

[0044] The performance tests were conducted on the aluminum alloys in Examples 1 to 3 and Comparative Examples 1 to 2. The mechanical strength was tested according to the standard GB / T6892-2023 "General Industrial Aluminum and Aluminum Alloy Extrusion Profiles", and the corrosion resistance was tested according to the standard GB / T10125-2021 "Artificial Atmosphere Corrosion Test Salt Spray Test". Table 1 shows the performance of the aluminum alloys in Examples 1-3 and Comparative Examples 1-2.

[0045] Table 1

[0046]

[0047] By comparing the data in Table 1, it can be seen that the present invention reasonably adjusts the processing technology of the high-Cu 6-series aluminum alloy so that the material takes into account corrosion resistance, strength and plasticity.

[0048] According to the disclosure of the above description, those skilled in the art to which the present invention belongs may also make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for preparing a high-Cu corrosion-resistant 6-series aluminum alloy, characterized in that: The method is carried out according to the following steps: The following raw material components are weighed in percentage by mass: Mg 1.0-1.03wt.%, Si 0.6-0.64wt.%, Cu 0.5-1.2wt.%, Mn≤0.12wt.%, Cr≤0.01wt.%, Ti≤0.01wt.%, Fe≤0.01wt.%, and the balance is Al and unavoidable impurities; Weigh raw materials according to the mass percentage of each element in the aluminum alloy, and perform smelting and casting to obtain an ingot; homogenizing the ingot of the above composition; The homogenized material is extruded, the extrusion rod temperature is 380-440°C, the extrusion speed is 12-20 m / min, and the outlet temperature is 480-530°C; Extrusions are quenched in salt water; The extruded material is artificially aged at 175-190℃ for 4-12h.

2. The method for preparing the high Cu corrosion-resistant 6 series aluminum alloy according to claim 1, characterized in that: The brine used in the brine quench contains 2-5 wt.% NaCl.

3. The method for preparing the high Cu corrosion-resistant 6 series aluminum alloy according to claim 2, characterized in that: The brine also contains ≤1 wt.% KCl.

4. The method for preparing the high Cu corrosion-resistant 6 series aluminum alloy according to claim 2, characterized in that: The temperature of the brine is 3-10°C.

5. The method for preparing the high Cu corrosion-resistant 6 series aluminum alloy according to claim 1, characterized in that: The aluminum alloy needs to be washed with water after being quenched in salt water.

6. The method for preparing the high Cu corrosion-resistant 6 series aluminum alloy according to claim 1, characterized in that: The homogenization treatment is specifically: keeping the temperature at 500-580° C. for 20-26 hours, and then air cooling to room temperature.

7. A high-Cu corrosion-resistant 6-series aluminum alloy, characterized in that: The alloy is prepared by the method for preparing the high-Cu corrosion-resistant 6-series aluminum alloy according to any one of claims 1 to 6.

8. The high Cu corrosion-resistant 6 series aluminum alloy according to claim 7, characterized in that: The high-Cu corrosion-resistant 6-series aluminum alloy has a yield strength greater than 340 MPa, a tensile strength greater than 380 MPa, and a plasticity greater than 10%.

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