A high-strength and tough aluminum alloy and hollow structural profile thereof and preparation method thereof

Abstract

The invention belongs to the technical field of high-strength and tough aluminum alloy profiles, and discloses a high-strength and tough aluminum alloy and a hollow structural profile and a preparation method thereof, wherein the high-strength and tough aluminum alloy comprises Si: 0-0.35; Fe: 0-0.4; Cu: 0.25-0.35; Mn: 0.3-0.5; Mg: 1.2-1.8; Cr: 0.1-0.2; Zn: 3.5-5.0; Zr: 0.05-0.2; Ti: 0-0.1; the remainder is aluminum and other inevitable impurity elements, and the content of the other inevitable impurities is less than 0.2. The aluminum alloy after optimizing the alloy composition of the invention not only has excellent welding performance, but also has excellent mechanical properties, and it is easy to prepare a high-strength and tough aluminum alloy hollow structural profile. The prepared hollow structural aluminum alloy profile has a yield strength greater than 340MPa, a tensile strength greater than 400MPa, and an elongation greater than 10%.

Description

Technical Field

[0001] The invention belongs to the technical field of high-strength and toughness aluminum alloy profiles, and in particular relates to a high-strength and toughness aluminum alloy and a hollow structure profile and a preparation method thereof. Background Art

[0002] Aluminum alloys are light (1 / 3 of steel), rust-proof, corrosion-resistant, and easy to recycle. Aluminum can be hardened or heat-treated to improve strength, thus achieving a high strength-to-weight ratio. Aluminum alloys have good processing properties and are suitable for different production processes such as casting, extrusion, stamping, forging, and machining. Aluminum alloys can also be strengthened to varying degrees by adding different alloying elements and heat treatment processes. Aluminum alloy surfaces are prone to forming dense oxide films and have good corrosion resistance. Aluminum alloys also have good electrical and thermal conductivity, and are non-magnetic. In addition, aluminum alloys have excellent recyclability. Therefore, aluminum alloy materials are widely used in the aviation industry, automobile manufacturing, power instruments, tools, and civil utensil manufacturing.

[0003] Aluminum profiles made of aluminum alloy are mainly used to manufacture various parts or welded parts on aircraft. With the rapid development of my country's aerospace industry, rail transportation, military vehicles and shipbuilding equipment industry, especially the launch of my country's large aircraft project, there is an urgent need for domestic production of high-quality and high-strength aluminum alloy profiles, especially hollow structure profiles. However, the mechanical properties of hollow structure aluminum profiles currently available are poor. Therefore, there is an urgent need for an aluminum alloy material with excellent mechanical properties and capable of extruding hollow structure aluminum profiles. Summary of the invention

[0004] In response to the above technical problems, the present invention also provides a high-strength and toughness aluminum alloy and its hollow structure profile and a preparation method. By optimizing the aluminum alloy composition, the aluminum alloy not only has excellent welding performance, but also has excellent mechanical properties, and it is easy to produce a hollow structure high-strength and toughness aluminum alloy profile.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] A high-strength and toughness aluminum alloy, calculated by mass percentage, includes Si: 0-0.35; Fe: 0-0.4; Cu: 0.25-0.35; Mn: 0.3-0.5; Mg: 1.2-1.8; Cr: 0.1-0.2; Zn: 3.5-5.0; Zr: 0.05-0.2; Ti: 0-0.1; the balance is aluminum and other inevitable impurity elements, and the content of the other inevitable impurities is less than 0.2.

[0007] Based on the same inventive concept, the present invention also provides a hollow structure aluminum alloy profile, which is made by extruding the aluminum alloy as described above, and the cross section of the hollow structure aluminum alloy profile has a plurality of closed figures.

[0008] Preferably, the closed shape is one of a square, a rectangle, a circle or a triangle, or a mixture thereof.

[0009] Preferably, the yield strength of the hollow structure aluminum alloy profile is greater than 340 MPa, the tensile strength is greater than 400 MPa, and the elongation is greater than 10%.

[0010] Based on the same inventive concept, the present invention also provides a method for preparing the hollow structure aluminum alloy profile, comprising the following steps:

[0011] S1: Melting the prepared high-strength and tough aluminum alloy raw materials into aluminum alloy ingots;

[0012] S2: Extruding the aluminum alloy ingot to obtain a hollow structure aluminum alloy profile.

[0013] Preferably, the step S2 specifically includes:

[0014] S201: placing the aluminum alloy ingot in an extruder for high-temperature extrusion to obtain a desired aluminum alloy profile, and controlling the profile outlet temperature to ensure that the extrusion outlet temperature is 510-530° C.;

[0015] S202: performing water cooling quenching treatment on the quenching device at the discharge port of the extruder;

[0016] S203: performing a double-stage aging heat treatment on the aluminum alloy profile after the quenching treatment in step S202.

[0017] Preferably, the two-stage aging heat treatment includes: a first-stage aging temperature of 95-135° C., a holding time of 5-15 hours, and a second-stage aging temperature of 145-165° C., a holding time of 10-30 hours.

[0018] Preferably, the step S201 is specifically as follows: preheating the ingot obtained in S1 at a preheating temperature of 450-470°C, preheating the tooling mold at a preheating temperature of 450-470°C, controlling the pressurization ratio and the profile outlet temperature to ensure that the extrusion outlet temperature is 510-530°C.

[0019] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0020] Aluminum alloy materials need to have excellent welding properties in order to manufacture hollow structural profiles. The aluminum alloy material of the present invention has excellent welding properties. The aluminum alloy of the present application can be used to manufacture hollow structural aluminum alloy profiles. In addition, the present invention optimizes the alloy content so that the yield strength of the aluminum alloy is greater than 340MPa, the tensile strength is greater than 400MPa, and the elongation is greater than 10%.

[0021] The present invention also realizes high-strength aluminum alloy profiles by controlling the process steps and process parameters in the preparation of hollow structure aluminum profiles.

[0022] The online quenching process in the present invention is an important means to achieve the excellent performance and cost control of the alloy. The present invention adopts a water-cooled online quenching process, and its main purposes include two aspects: first, the water-cooled quenching speed is fast, which can ensure that the alloy elements form a supersaturated solid solution in the aluminum alloy matrix; second, although the residual stress of the profile after quenching is relatively large, the present invention adds a two-stage aging treatment, which can effectively reduce the adverse effects caused by the residual stress.

[0023] The aging process in the present invention is an important step to achieve the excellent performance of the alloy. The present invention uses a two-stage aging treatment, which can not only effectively release the residual stress caused by quenching, but also adjust the alloy precipitation sequence and precipitation phase morphology through the alloy, so that the alloy has high-strength and toughness mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The cross section of the hollow structure aluminum alloy profile of Example 1 of the present invention is shown in FIG. Figure 1 ;

[0025] Figure 2 The cross section of the hollow structure aluminum alloy profile of Example 1 of the present invention is shown in FIG. Figure 2 ;

[0026] Figure 3 The cross section of the hollow structure aluminum alloy profile of Example 1 of the present invention is shown in FIG. Figure 3 . DETAILED DESCRIPTION

[0027] The following is a further detailed description of a high-strength and toughness aluminum alloy and a hollow structural profile and a preparation method thereof proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description.

[0028] Example 1

[0029] A high-strength and tough aluminum alloy, the mass percentage of which is:

[0030]

[0031] A method for preparing a hollow structure aluminum alloy profile comprises the following steps:

[0032] S1: adding the prepared high-strength and tough aluminum alloy raw materials into a melting furnace, uniformly mixing and then melting into liquid aluminum alloy, and melting the liquid aluminum alloy into aluminum alloy ingots;

[0033] S2: preheating the ingot obtained in S1 to a temperature of 450-470° C., preheating the tooling mold to a temperature of 450-470° C., controlling the pressure ratio and the profile outlet temperature to ensure that the extrusion outlet temperature is 510-530° C.;

[0034] S3: performing water cooling quenching treatment on the quenching device at the discharge port of the extruder;

[0035] S4: The aluminum alloy profile after quenching treatment in step S202 is subjected to a two-stage aging heat treatment: the first stage aging temperature is 95-135°C, the holding time is 5-15h, the second stage aging temperature is 145-165°C, the holding time is 10-30h. During aging, the temperature can be raised with the furnace, or it can be raised to the aging temperature and then placed in the heat treatment furnace. After aging, it can be cooled with the furnace or air-cooled.

[0036] According to different molds, Figure 1-3 Hollow structural profile shown.

[0037] Comparative Example 1

[0038] The mass percentage of national standard 7005 aluminum alloy is:

[0039]

[0040] Comparative Example 2

[0041] The mass percentage of national standard 7021 aluminum alloy is:

[0042]

[0043] Comparative Example 3

[0044] The mass percentage of national standard 7022 aluminum alloy is:

[0045]

[0046] The preparation method of the aluminum alloy profiles of Comparative Examples 1-3 is the same as that of Example 1, and the following Figure 1-3 The hollow structure aluminum profile shown in the figure cannot be obtained in Comparative Examples 2 and 3. Figure 1-3 The hollow structural profile of the structure shown in the figure was prepared, and the mechanical properties of the aluminum alloys of Example 1 and Comparative Examples 1-3 were measured. The results are shown in the following table:

[0047]

[0048] From the above table, it can be seen that the tensile strength of 7021 and 7022 aluminum alloys is very high, but they cannot be extruded into hollow structure aluminum profiles, and cannot be welded into closed sections; 7005 aluminum alloy has good welding performance and is relatively easy to extrude into hollow structure aluminum profiles, but has low tensile strength; the aluminum alloy of the present invention is not only easy to extrude into hollow structure aluminum profiles, indicating good welding performance, but also has a yield strength greater than 340MPa, a tensile strength greater than 400MPa, and an elongation greater than 10%, indicating good mechanical properties.

[0049] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A hollow structure aluminum alloy profile, characterized in that: The aluminum alloy of the hollow structure aluminum alloy profile comprises, by mass percentage, Si: 0-0.35; Fe: 0-0.4; Cu: 0.25-0.35; Mn: 0.3-0.5; Mg: 1.2~1.8; Cr: 0.1~0.2; Zn: 3.5~5.0; Zr: 0.05-0.2; Ti: 0-0.1; the balance is aluminum and other inevitable impurity elements, the content of the other inevitable impurities is less than 0.2; The cross section of the hollow structure aluminum alloy profile has at least two closed figures; The method for preparing the hollow structure aluminum alloy profile comprises: S1: melting the prepared aluminum alloy raw materials into aluminum alloy ingots; S2: Extruding the aluminum alloy ingot to obtain a hollow structure aluminum alloy profile: S201: placing the aluminum alloy ingot in an extruder for high-temperature extrusion to obtain a desired aluminum alloy profile, and controlling the profile outlet temperature to ensure that the extrusion outlet temperature is 510-530° C.; S202: performing water cooling quenching treatment on the quenching device at the discharge port of the extruder; S203: Perform a double-stage aging heat treatment on the aluminum alloy profile after the quenching treatment in step S202: the double-stage aging heat treatment includes: a first-stage aging temperature of 95-135°C, a holding time of 5-15h; a second-stage aging temperature of 145-165°C, a holding time of 10-30h.

2. The hollow structure aluminum alloy profile according to claim 1, characterized in that: The closed figure is one of a square, a rectangle, a triangle or a circle, or a mixture thereof.

3. The hollow structure aluminum alloy profile according to claim 1 or 2, characterized in that: The yield strength of the hollow structure aluminum alloy profile is greater than 340 MPa, the tensile strength is greater than 400 MPa, and the elongation is greater than 10%.

4. A method for preparing a hollow structure aluminum alloy profile according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: melting the prepared aluminum alloy raw materials into aluminum alloy ingots; S2: Extruding the aluminum alloy ingot to obtain a hollow structure aluminum alloy profile; The step S2 specifically includes: S201: placing the aluminum alloy ingot in an extruder for high-temperature extrusion to obtain a desired aluminum alloy profile, and controlling the profile outlet temperature to ensure that the extrusion outlet temperature is 510-530° C.; S202: performing water cooling quenching treatment on the quenching device at the discharge port of the extruder; S203: performing a double-stage aging heat treatment on the aluminum alloy profile after the quenching treatment in step S202; The double-stage aging heat treatment includes: the first stage aging temperature is 95-135° C., and the holding time is 5-15 hours; the second stage aging temperature is 145-165° C., and the holding time is 10-30 hours.

5. The method for preparing a hollow structure aluminum alloy profile according to claim 4, characterized in that: The step S201 is specifically as follows: preheating the ingot obtained in S1 to a temperature of 450-470°C, preheating the tooling to a temperature of 450-470°C, controlling the pressurization ratio and the profile outlet temperature to ensure that the extrusion outlet temperature is 510-530°C.

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