Zirconium-containing 6-series aluminum alloy profile for high-strength threshold beam of new energy automobile

Abstract

The invention provides a zirconium-containing 6-series aluminum alloy profile for a high-strength threshold beam of a new energy automobile, and relates to the technical field of aluminum alloy profiles. The invention discloses a zirconium-containing 6-series aluminum alloy profile for a high-strength threshold beam of a new energy automobile. The zirconium-containing 6-series aluminum alloy profile comprises the following chemical components in percentage by mass: 0.6-0.9% of Si, 0.1-0.4% of Cu, 0.4-0.7% of Mn, 0.7-1.2% of Mg, 0.05-0.35% of Cr, 0.05-1% of Zr, less than or equal to 0.2% of Zn, less than or equal to 0.3% of Fe, less than or equal to 0.1% of Ti and the balance of Al and inevitable impurities. The aluminum alloy profile provided by the invention has excellent mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy profiles, and in particular to a zirconium-containing 6-series aluminum alloy profile for high-strength door sill beams of new energy vehicles. Background Art

[0002] New energy vehicles have an urgent need for lightweight bodies. As a key load-bearing component of the body, the rocker beam must meet the requirements of high strength, collision resistance and corrosion resistance. Although traditional 6-series aluminum alloys are lightweight, their yield strength is generally lower than 300 MPa, and their performance is easily degraded due to intergranular corrosion during long-term use. In existing technologies, the strength is improved by adding elements such as Cu and Mn, but this sacrifices formability and cannot effectively suppress the problem of grain coarsening under dynamic loads. Zirconium, as a grain refiner, can form a stable ZrAl3 phase. Therefore, there is an urgent need to develop a zirconium-containing 6-series aluminum alloy profile for high-strength rocker beams of new energy vehicles, which is of great significance for the widespread application of aluminum alloys. Summary of the Invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes a zirconium-containing 6-series aluminum alloy profile for high-strength door sill beams of new energy vehicles.

[0004] The present invention proposes a zirconium-containing 6-series aluminum alloy profile for a high-strength door sill beam of a new energy vehicle. The chemical composition of the profile comprises, by mass percentage, the following: Si 0.6-0.9%, Cu 0.1-0.4%, Mn 0.4-0.7%, Mg 0.7-1.2%, Cr 0.05-0.35%, Zr 0.05-1%, Zn ≤ 0.2%, Fe ≤ 0.3%, Ti ≤ 0.1%, and the balance being Al and unavoidable impurities.

[0005] The present invention also provides a method for preparing a zirconium-containing 6-series aluminum alloy profile for a high-strength sill beam of a new energy vehicle, comprising the following steps:

[0006] S1. Weighing raw materials according to the chemical composition of a zirconium-containing 6-series aluminum alloy profile for a high-strength sill beam of a new energy vehicle, and performing smelting, refining, impurity removal, and grain refinement to obtain an aluminum alloy melt;

[0007] S2, casting the aluminum alloy melt to obtain an aluminum alloy cast rod;

[0008] S3, performing homogenization heat treatment on the aluminum alloy cast rod and sawing it into short rods;

[0009] S4, extruding the short rod, quenching it online, and stretching it to obtain a pretreated aluminum alloy profile;

[0010] S5. Performing aging treatment on the pretreated aluminum alloy profile to obtain a zirconium-containing 6 series aluminum alloy profile for a high-strength door sill beam of a new energy vehicle.

[0011] Preferably, in said S1, the melting temperature is 710-780°C.

[0012] Preferably, in said S1, the refining and impurity removal comprises spraying a protective gas and a refining agent on the smelted aluminum alloy liquid to perform refining and impurity removal.

[0013] More preferably, the amount of the refining agent is 2-2.5 kg / t aluminum alloy liquid.

[0014] Preferably, in the above-mentioned S1, the grain refining agent is an Al-Ti-B refining agent.

[0015] Preferably, in said S2, the casting is performed by a hot top method or an air sliding method.

[0016] Preferably, in said S3, the homogenization heat treatment comprises first heating to 550-570°C at a rate of 50-100°C / h and keeping the temperature for 3-5h, then cooling to 220-280°C by strong wind, and finally cooling to room temperature by spraying.

[0017] By controlling the heating rate and temperature range of the homogenization heat treatment, composition segregation can be eliminated and the uniform precipitation of the Al3Zr phase can be promoted.

[0018] Preferably, in said S4, the extrusion molding process temperature is 460-520° C. and the extrusion ratio is (20-25):1.

[0019] Controlling extrusion parameters helps ensure uniform wall thickness.

[0020] Preferably, in said S4, the online quenching includes strong wind cooling or water spray cooling.

[0021] Preferably, in said S5, the aging treatment comprises heating to 165-175°C at a rate of 50-100°C / h, keeping the temperature for 5-8h, and then cooling to room temperature with strong wind.

[0022] The beneficial effects of the present invention are:

[0023] The zirconium-containing 6-series aluminum alloy profile for high-strength sill beams of new energy vehicles provided by the present invention comprises Si, Cu, Mn, Mg, Cr, Zr, Zn, Fe, Ti, and Al, and the elements are controlled within a certain range. The various elements in the present invention act synergistically, and the obtained zirconium-containing 6-series aluminum alloy profile has high strength and can be applied to sill beams of new energy vehicles.

[0024] In this invention, the introduction of zirconium (Zr) achieves a grain refinement effect by forming an Al3Zr dispersed phase, while simultaneously producing a synergistic grain control effect with titanium (Ti), jointly optimizing the material's microstructural uniformity. Furthermore, the combined addition of zirconium (Zr) and chromium (Cr) promotes the formation of a coherent interface structure, significantly enhancing the density and chemical stability of the surface oxide film. This synergistic effect effectively curbs grain expansion during solution heat treatment, thereby preventing the formation of coarse-grained rings and improving the overall mechanical properties of the profile.

[0025] In terms of alloy system design, the aluminum alloy profile of the present invention uses magnesium (Mg) and silicon (Si) as the main alloying components, and the uniform precipitation of the strengthening phase Mg2Si is promoted by precisely controlling the Mg / Si stoichiometric ratio. On this basis, the appropriate amount of trace elements of copper (Cu) or zinc (Zn) is introduced to achieve a synergistic effect of solid solution strengthening and precipitation strengthening while maintaining the inherent corrosion resistance of the material, achieving an optimal balance between strength and corrosion resistance. This component design strategy breaks through the technical bottleneck of the traditional aluminum alloy strength-corrosion resistance trade-off through multi-scale precipitation phase regulation and element interaction. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described in detail through specific embodiments.

[0027] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0028] Example 1

[0029] A zirconium-containing 6-series aluminum alloy profile for high-strength sill beams of new energy vehicles has a chemical composition, by mass percentage, comprising: 0.7% Si, 0.2% Cu, 0.5% Mn, 0.9% Mg, 0.15% Cr, 0.15% Zr, 0.05% Zn, 0.2% Fe, 0.1% Ti, with the balance being Al and unavoidable impurities.

[0030] A method for preparing a zirconium-containing 6-series aluminum alloy profile for a high-strength sill beam of a new energy vehicle comprises the following steps:

[0031] S1. Raw materials are weighed according to the chemical composition of zirconium-containing 6-series aluminum alloy profiles for high-strength sill beams of new energy vehicles and smelted at 750° C.; the aluminum alloy liquid in the smelting furnace is refined and impurities removed using nitrogen and a 2 kg / t refining agent; and an Al-Ti-B refiner is used to perform grain refinement to obtain an aluminum alloy melt;

[0032] S2, casting the aluminum alloy melt by air-sliding method to obtain aluminum alloy casting rods;

[0033] S3. Homogenizing the aluminum alloy cast rods: first, heating the rods to 560°C at a rate of 100°C / h and holding the temperature for 4 hours, then cooling them to 260°C with a strong wind, and finally spray cooling them to room temperature, and sawing them to obtain short rods;

[0034] S4, extruding the short rod at 480° C. with an extrusion ratio of 25:1, performing strong wind cooling on-line quenching, and stretching to obtain a pretreated aluminum alloy profile;

[0035] S5. Performing aging treatment on the pretreated aluminum alloy profile: heating to 170°C at a rate of 100°C / h, keeping the temperature for 6 hours, and then cooling to room temperature with strong wind to obtain a zirconium-containing 6 series aluminum alloy profile for high-strength door sill beams of new energy vehicles.

[0036] Example 2

[0037] A zirconium-containing 6-series aluminum alloy profile for high-strength sill beams of new energy vehicles has a chemical composition, by mass percentage, comprising: 0.8% Si, 0.2% Cu, 0.4% Mn, 1% Mg, 0.1% Cr, 0.15% Zr, 0.05% Zn, 0.3% Fe, 0.1% Ti, with the balance being Al and unavoidable impurities.

[0038] A method for preparing a zirconium-containing 6-series aluminum alloy profile for a high-strength sill beam of a new energy vehicle comprises the following steps:

[0039] S1. Raw materials are weighed according to the chemical composition of zirconium-containing 6-series aluminum alloy profiles for high-strength sill beams of new energy vehicles and smelted at 750° C.; the aluminum alloy liquid in the smelting furnace is refined and impurities removed using nitrogen and a 2.2 kg / t refining agent; and an Al-Ti-B refiner is used to perform grain refinement to obtain an aluminum alloy melt;

[0040] S2, casting the aluminum alloy melt by air-sliding method to obtain aluminum alloy casting rods;

[0041] S3, homogenizing the aluminum alloy cast rods by heating them to 560°C at a rate of 80°C / h and holding for 4 hours, then cooling them to 220°C with a strong wind, and finally cooling them to room temperature by spraying, and sawing them to obtain short rods;

[0042] S4, extruding the short rod at 500° C. with an extrusion ratio of 25:1, quenching online by strong wind cooling, and stretching to obtain a pretreated aluminum alloy profile;

[0043] S5. Performing aging treatment on the pretreated aluminum alloy profile: heating to 170°C at a rate of 100°C / h, keeping the temperature for 6 hours, and then cooling to room temperature with strong wind to obtain a zirconium-containing 6 series aluminum alloy profile for high-strength door sill beams of new energy vehicles.

[0044] Example 3

[0045] A zirconium-containing 6-series aluminum alloy profile for high-strength sill beams of new energy vehicles has a chemical composition, by mass percentage, comprising: 0.8% Si, 0.25% Cu, 0.4% Mn, 1.15% Mg, 0.1% Cr, 0.2% Zr, 0.05% Zn, 0.3% Fe, 0.1% Ti, with the balance being Al and unavoidable impurities.

[0046] A method for preparing a zirconium-containing 6-series aluminum alloy profile for a high-strength sill beam of a new energy vehicle comprises the following steps:

[0047] S1. Raw materials are weighed according to the chemical composition of a zirconium-containing 6-series aluminum alloy profile for high-strength sill beams of new energy vehicles and smelted at 760° C.; the aluminum alloy liquid in the smelting furnace is refined and impurities removed using nitrogen and a 2 kg / t refining agent; and an Al-Ti-B refiner is used to perform grain refinement to obtain an aluminum alloy melt;

[0048] S2, casting the aluminum alloy melt by air-sliding method to obtain aluminum alloy casting rods;

[0049] S3, homogenizing the aluminum alloy cast rod by heating it to 560°C at a rate of 80°C / h and holding it for 4 hours, then cooling it to 260°C with a strong wind, and finally cooling it to room temperature by spraying, and sawing it to obtain short rods;

[0050] S4, extruding the short rod at 480° C. with an extrusion ratio of 25:1, performing strong wind cooling on-line quenching, and stretching to obtain a pretreated aluminum alloy profile;

[0051] S5. Performing aging treatment on the pretreated aluminum alloy profile: heating to 175° C. at a rate of 100° C. / h, keeping the temperature for 6 hours, and then cooling to room temperature with strong wind to obtain a zirconium-containing 6 series aluminum alloy profile for high-strength door sill beams of new energy vehicles.

[0052] The tensile strength and yield strength of the aluminum alloy profiles were tested. The test results are shown in Table 1.

[0053] Table 1

[0054] Group Tensile strength / MPa Yield strength / MPa Example 1 380 347 Example 2 371 341 Example 3 384 348

[0055] After the aluminum alloy profile of Example 1 was subjected to a neutral salt spray test for 540 hours according to GB / T10125-2012 "Artificial atmosphere corrosion test salt spray test", the defect area was 3.6%.

[0056] In summary, the aluminum alloy profile provided by the present invention has high strength and excellent corrosion resistance.

[0057] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A zirconium-containing 6-series aluminum alloy profile for high-strength sill beams of new energy vehicles, characterized in that: Its chemical composition includes, by mass percentage, Si 0.6-0.9%, Cu 0.1-0.4%, Mn 0.4-0.7%, Mg 0.7-1.2%, Cr 0.05-0.35%, Zr 0.05-1%, Zn≤0.2%, Fe≤0.3%, Ti≤0.1%, and the balance is Al and unavoidable impurities.

2. A method for preparing the zirconium-containing 6-series aluminum alloy profile for high-strength sill beams of new energy vehicles according to claim 1, characterized in that: The following steps are involved: S1. Weighing raw materials according to the chemical composition of a zirconium-containing 6-series aluminum alloy profile for a high-strength sill beam of a new energy vehicle, and performing smelting, refining, impurity removal, and grain refinement to obtain an aluminum alloy melt; S2, casting the aluminum alloy melt to obtain an aluminum alloy cast rod; S3, performing homogenization heat treatment on the aluminum alloy cast rod and sawing it into short rods; S4, extruding the short rod, quenching it online, and stretching it to obtain a pretreated aluminum alloy profile; S5. Performing aging treatment on the pretreated aluminum alloy profile to obtain a zirconium-containing 6 series aluminum alloy profile for a high-strength door sill beam of a new energy vehicle.

3. The preparation method according to claim 2, characterized in that In the above-mentioned S1, the grain refining agent is an Al-Ti-B refining agent.

4. The preparation method according to claim 2, characterized in that In the above-mentioned S2, the casting is performed by a hot top method or an air sliding method.

5. The preparation method according to claim 2, characterized in that In the above-mentioned S3, the homogenization heat treatment includes first heating the temperature to 550-570°C at a rate of 50-100°C / h and keeping the temperature for 3-5h, then cooling the temperature to 220-280°C with strong wind, and finally cooling the temperature to room temperature by spraying.

6. The preparation method according to claim 2, characterized in that In the S4, the extrusion molding process temperature is 460-520° C. and the extrusion ratio is (20-25):

1.

7. The preparation method according to claim 2, characterized in that In the above-mentioned S4, the online quenching includes strong wind cooling or water spray cooling.

8. The preparation method according to claim 2, characterized in that In the above-mentioned S5, the aging treatment includes heating to 165-175°C at a rate of 50-100°C / h, keeping the temperature for 5-8h, and then cooling to room temperature with strong wind.