Mg-Zn-Cr series aluminum alloy strengthening and toughening aging process

Abstract

The invention discloses an Mg-Zn-Cr series aluminum alloy strengthening and toughening aging process, and belongs to the technical field of metal material engineering. The aging process comprises the two steps that rapid heating aging is conducted at the aging temperature of 150 DEG C, the heating rate is 1.5 DEG C / min, the heat preservation time is 10 h, then standing and cooling are conducted to the room temperature, secondary aging is conducted at the secondary aging temperature of 150 DEG C, the heating rate is 0.5 DEG C / min, and the aging time is 5 h. The alloy has high strength when used in the aging process. The aluminum alloy comprises the following components: 0.8-1% of Mg, 5.1-6% of Zn, 0.12-0.3% of Zr, less than or equal to 0.05% of other impurities and the balance of Al. The process technology is suitable for producing aluminum alloy thick plates and thin plates for aerospace, rail transit and automobiles.

Description

Technical Field

[0001] The invention relates to the technical field of metal material engineering, and in particular to a strengthening and toughening aging process for a Mg-Zn-Cr series aluminum alloy. Background Art

[0002] Mg-Zn-Cr aluminum alloys are widely used in aerospace, automobile manufacturing, electronic equipment and other fields due to their excellent mechanical properties, good corrosion resistance and low density. However, the current pain points mainly include low strength, poor toughness, poor machinability and other problems, which limit their application in some complex structural parts and key connection parts. In addition, with the increasing demand for high-strength and high-performance materials, how to further improve their strength, toughness and heat resistance remains an important challenge in research and development. Summary of the invention

[0003] In order to solve the above-mentioned deficiencies existing in the prior art, the purpose of the present invention is to provide a Mg-Zn-Cr aluminum alloy strengthening and toughening aging process, using Mg-Zn-Cr aluminum alloy thin plate or thick plate as raw material, and controlling the heating rate, aging temperature and holding time of the two-step aging process to control the dispersion of the second phase precipitated from the Mg-Zn-Cr aluminum alloy, which not only effectively solves the problem of low strength of Mg-Zn-Cr aluminum alloy, but also makes it have higher toughness.

[0004] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0005] The invention discloses a strengthening and toughening aging process for Mg-Zn-Cr aluminum alloy. The process uses Mg-Zn-Cr aluminum alloy as raw material, performs two-step aging treatment on the alloy, and controls the heating rate, aging temperature and holding time of the two-step artificial aging treatment, thereby controlling the dispersion of the second phase precipitated from the Mg-Zn-Cr aluminum alloy, thereby improving the strength and toughness of the Mg-Zn-Cr aluminum alloy.

[0006] The Mg-Zn-Cr aluminum alloy strengthening and toughening aging process comprises the following steps:

[0007] (1) Primary aging treatment: After cleaning the surface of the raw material, place it in a heat treatment furnace at room temperature, set the heating rate to 1.0-1.5°C / min, raise it to 140-150°C, then keep it warm for 8-10 hours, cool it to room temperature with the furnace and take it out;

[0008] (2) Secondary aging treatment: The sample after the first artificial aging treatment is placed in the heat treatment furnace, and the parameters of the secondary aging treatment are set as follows: the heating rate is 0.25-0.5℃ / min, raised to 140-150℃, then kept at this temperature for 5-8h, cooled to room temperature with the furnace and taken out.

[0009] Furthermore, the Mg-Zn-Cr aluminum alloy raw material is a thin plate or a thick plate.

[0010] Furthermore, the chemical composition of the Mg-Zn-Cr aluminum alloy is, by weight percentage, Mg 0.8-1%, Zn 5.1-6%, Zr 0.12-0.3%, other impurities ≤0.05% in a single phase, and the balance is Al.

[0011] Furthermore, the heat treatment furnace is a muffle furnace or a tubular furnace.

[0012] Furthermore, the aging process is used for strengthening and toughening of Mg-Zn-Cr aluminum alloys.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The Mg-Zn-Cr aluminum alloy strengthening and toughening process provided by the present invention makes the second phase precipitation more uniform through a two-step aging strengthening and toughening process, thereby improving the mechanical properties of the aluminum alloy and the toughness to a certain extent.

[0015] 2. The method of the present invention has simple principle, simple process, no pollution, low equipment requirements, high efficiency, high yield rate, and can obtain aluminum alloy materials with good comprehensive strength and toughness, which is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the stress-strain curve of the artificially aged Mg-Zn-Cr aluminum alloy in Example 1.

[0017] Figure 2 This is the stress-strain curve of the artificially aged Mg-Zn-Cr aluminum alloy of comparative example 1. DETAILED DESCRIPTION

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0019] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0020] Example 1

[0021] This embodiment provides a Mg-Zn-Cr aluminum alloy strengthening and toughening process, and the specific process is as follows:

[0022] (1) Cut the aluminum alloy sheet into sheets of 200 mm × 50 mm × 2.8 mm thick, clean them with a detergent and blow dry them, put the cleaned sheets into a muffle furnace, and wait for the first step of aging.

[0023] (2) First step of aging: Set the muffle furnace program and set the heating rate to 1.5°C / min, raise the temperature to 150°C, then keep it at this temperature for 10 h, cool it to room temperature and take it out.

[0024] (3) Second aging step: After the first aging step, the sheet is placed back in the muffle furnace and the program is set: the heating rate is 0.5°C / min, raised to 150°C, then kept at this temperature for 5 hours, cooled to room temperature and taken out.

[0025] (4) The aluminum alloy after two-step aging is cut into standard tensile specimens and hardness specimens using a wire cutting machine, waiting for the mechanical properties to be tested.

[0026] Example 2

[0027] This embodiment provides a Mg-Zn-Cr aluminum alloy strengthening and toughening process, and the specific process is as follows:

[0028] (1) Cut the aluminum alloy sheet into sheets of 200 mm × 50 mm × 2.8 mm thick, clean them with a detergent and blow dry them, put the cleaned sheets into a muffle furnace, and wait for the first step of aging.

[0029] (2) First step of aging: Set the muffle furnace program and set the heating rate to 1.25°C / min, raise the temperature to 150°C, then keep it at that temperature for 10 h, cool it to room temperature and take it out.

[0030] (3) Second aging step: After the first aging step, the sheet is placed back in the muffle furnace and the program is set: the heating rate is 0.5°C / min, raised to 150°C, then kept at this temperature for 5 hours, cooled to room temperature and taken out.

[0031] (4) The aluminum alloy after two-step aging is cut into standard tensile specimens and hardness specimens using a wire cutting machine, waiting for the mechanical properties to be tested.

[0032] Example 3

[0033] This embodiment provides a Mg-Zn-Cr aluminum alloy strengthening and toughening process, and the specific process is as follows:

[0034] (1) Cut the aluminum alloy sheet into sheets of 200 mm × 50 mm × 2.8 mm thick, clean them with a detergent and blow dry them, put the cleaned sheets into a muffle furnace, and wait for the first step of aging.

[0035] (2) First step of aging: Set the muffle furnace program and set the heating rate to 1.25°C / min to 140°C. Then keep the temperature for 9 hours, cool it to room temperature and take it out.

[0036] (3) Second aging step: After the first aging step, the sheet is placed back in the muffle furnace and the program is set: the heating rate is 0.5°C / min, raised to 150°C, then kept at this temperature for 5 hours, cooled to room temperature and taken out.

[0037] (4) The aluminum alloy after two-step aging is cut into standard tensile specimens and hardness specimens using a wire cutting machine, waiting for the mechanical properties to be tested.

[0038] Comparative Example 1

[0039] This embodiment provides a Mg-Zn-Cr aluminum alloy strengthening and toughening process, and the specific process is as follows. The only difference from Example 1 is that only the first step of aging is processed.

[0040] (1) Cut the aluminum alloy sheet into sheets of 200 mm × 50 mm × 2.8 mm thick, clean them with a detergent and blow dry them, put the cleaned sheets into a muffle furnace, and wait for the first step of aging.

[0041] (2) First step of aging: Set the muffle furnace program and set the heating rate to 1.25°C / min, raise the temperature to 150°C, then keep it at that temperature for 10 h, cool it to room temperature and take it out.

[0042] (3) The aluminum alloy after two-step aging is cut into standard tensile specimens and hardness specimens using a wire cutting machine, waiting for the mechanical properties to be tested

[0043] Performance Testing

[0044] The microhardness and ultimate tensile strength of the composite materials or aluminum materials prepared in the above embodiments and comparative examples were tested, wherein:

[0045] Microhardness test: Shanghai Hengyi EM500-1A microhardness tester was used, with a loading force of 200 gf and a holding time of 15 s;

[0046] Ultimate tensile strength test: using Instron 34FM-100 electronic universal material testing machine, the tensile speed is 5mm / min;

[0047] The test results are summarized in Table 1.

[0048] Table 1

[0049]

[0050] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A Mg-Zn-Cr aluminum alloy strengthening and toughening aging process, characterized in that: The process uses Mg-Zn-Cr aluminum alloy as raw material, subjects it to a two-step aging treatment, and controls the dispersion of the second phase precipitated from the Mg-Zn-Cr aluminum alloy by controlling the heating rate, aging temperature and holding time of the two-step aging treatment, thereby improving the strength and toughness of the Mg-Zn-Cr aluminum alloy.

2. The Mg-Zn-Cr aluminum alloy strengthening and toughening aging process according to claim 1, characterized in that: The process includes the following steps: (1) Primary aging treatment: After cleaning the surface of the raw material, place it in a heat treatment furnace at room temperature, set the heating rate to 1.0-1.5°C / min, raise it to 140-150°C, then keep it warm for 8-10 hours, cool it to room temperature with the furnace and take it out; (2) Secondary aging treatment: The sample after the first aging treatment is placed in the heat treatment furnace, and the parameters of the secondary aging treatment are set as follows: the heating rate is 0.25-0.5℃ / min, raised to 140-150℃, then kept at this temperature for 5-8h, cooled to room temperature with the furnace and taken out.

3. The Mg-Zn-Cr aluminum alloy strengthening and toughening aging process according to claim 1, characterized in that: The Mg-Zn-Cr aluminum alloy raw material is a thin plate or a thick plate.

4. The Mg-Zn-Cr aluminum alloy strengthening and toughening aging process according to claim 1, characterized in that: The chemical composition of the Mg-Zn-Cr aluminum alloy is as follows by weight percentage: Mg 0.8-1%, Zn 5.1-6%, Zr 0.12-0.3%, other impurities single phase ≤0.05%, and the balance is Al.

5. The Mg-Zn-Cr aluminum alloy strengthening and toughening aging process according to claim 1, characterized in that: The heat treatment furnace is a muffle furnace or a tubular furnace.

6. The Mg-Zn-Cr aluminum alloy strengthening and toughening aging process according to claim 1, characterized in that: The aging process is used for strengthening and toughening of Mg-Zn-Cr aluminum alloys.

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