High-strength threshold beam aluminum alloy profile and preparation method thereof

Abstract

The invention relates to the technical field of aluminum alloy profile preparation, and discloses a high-strength threshold beam aluminum alloy profile and a preparation method thereof.The high-strength threshold beam aluminum alloy profile is prepared from, by weight, 85-90 parts of aluminum ingots, 0.8-1.5 parts of silicon, 0.6-1.2 parts of magnesium, 0.3-0.8 part of copper, 0.2-0.6 part of zinc, 0.4-0.9 part of manganese, 0.05-0.15 part of titanium, 0.1-0.3 part of zirconium, 0.05-0.1 part of chromium and 0.02-0.08 part of yttrium. Through the vacuum induction melting and electromagnetic stirring processes, the situation that alloy elements such as silicon, copper and zinc form a thick second phase in the melting process is avoided, the alloy structure is refined, and crack initiation points are reduced, so that the toughness of the material is effectively improved, the material is not prone to breakage when bearing impact, and the safety of the automobile doorsill beam during collision is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy profile preparation, and particularly relates to a high-strength sill beam aluminum alloy profile and a preparation method thereof. Background Art

[0002] In the field of automobile manufacturing, with the continuous improvement of requirements for vehicle safety, lightweight, and performance, high-strength sill beam aluminum alloy profiles have gradually become a research and application hotspot. This profile is a high-performance aluminum alloy material specifically used for the position of the automobile sill beam, with characteristics such as high strength, high elongation rate, and good corrosion resistance. Its main components include elements such as silicon, copper, zinc, magnesium, and manganese. Through precise proportioning and advanced processing technology, it can meet the high-strength requirements of the sill beam during side collisions of automobiles, and at the same time ensure the toughness and durability of the material. During a side collision of an automobile, the sill beam can withstand a large impact force and absorb energy through deformation, thereby protecting the safety of the driver and passengers. In addition, the sill beam can also prevent safety problems caused by the deformation of the battery pack housing due to collision in new energy vehicles;

[0003] However, in the preparation process of high-strength sill beam aluminum alloy profiles, there are certain problems with traditional melting processes. Since this profile requires high contents of alloying elements such as silicon, copper, and zinc, these elements are prone to forming coarse second phases during traditional melting. These coarse second phases will be distributed in the aluminum alloy matrix and become the initiation points of cracks, thereby reducing the toughness of the material.

[0004] To solve the above problems, a high-strength sill beam aluminum alloy profile and a preparation method thereof are proposed in this application. Summary of the Invention

[0005] The present invention proposes a high-strength sill beam aluminum alloy profile and a preparation method thereof, which solve the problem in related technologies that traditional melting processes require high contents of alloying elements such as silicon, copper, and zinc, and these elements are prone to forming coarse second phases during traditional melting, reducing the toughness of the material.

[0006] As shown in Figure 1 A high-strength sill beam aluminum alloy profile proposed by the present invention has the following raw material composition by weight:

[0007] 85 - 90 parts of aluminum ingot, 0.8 - 1.5 parts of silicon, 0.6 - 1.2 parts of magnesium, 0.3 - 0.8 parts of copper, 0.2 - 0.6 parts of zinc, 0.4 - 0.9 parts of manganese, 0.05 - 0.15 parts of titanium, 0.1 - 0.3 parts of zirconium, 0.05 - 0.1 parts of chromium, 0.02 - 0.08 parts of yttrium.

[0008] A preparation method of an aluminum alloy profile for a high-strength sill beam, using the high-strength aluminum alloy profile for a sill beam as claimed in claim 1, comprising the following steps:

[0009] Step 1: Raw material pretreatment. The aluminum ingot is crushed into particles of 10 - 20 mm, and the remaining metals are ball-milled.

[0010] Step 2: Vacuum induction melting. Melting is carried out under the protection of inert gas for 30 minutes, and silicon, copper, and zinc are added.

[0011] Step 3: Electromagnetic stirring. A magnetic field with a frequency of 20 kHz is applied for stirring for 15 minutes to eliminate compositional segregation.

[0012] Step 4: Gradient homogenization treatment. First, hold at 450 °C for 4 hours, and then raise the temperature to 520 °C and hold for 2 hours to eliminate the low-melting eutectic phase.

[0013] Step 5: Multi-pass hot extrusion. The extrusion temperature is 480 - 500 °C, the extrusion ratio is 12:1, and the deformation amount per pass is less than 40%.

[0014] Step 6: Double-stage solution treatment and aging, which are divided into primary solution treatment, secondary solution treatment, and step-by-step aging.

[0015] Step 7: Micro-arc oxidation treatment. The electrolyte contains sodium silicate and phosphate, the voltage is 350 V, and a ceramic layer of 10 - 15 μm is formed.

[0016] Step 8: Detection and finishing. Use an instrument for flaw detection to detect internal defects of the product.

[0017] As a further optimized solution of the present invention, the raw material pretreatment in Step 1 specifically includes:

[0018] S1: Crush the aluminum ingot into particles of 10 - 20 mm;

[0019] S2: Ball-mill the metal powders of silicon, magnesium, copper, zinc, manganese, titanium, zirconium, chromium, and yttrium until D50 ≤ 5 μm;

[0020] S3: Screen the ball-milled powders through a 200-mesh sieve to remove agglomerates.

[0021] As a further optimized solution of the present invention, the vacuum induction melting in Step 2 specifically includes:

[0022] S1: Place the aluminum ingot particles in a vacuum induction furnace, evacuate to 1 × 10-3 Pa, and then fill with argon to 0.5 MPa;

[0023] S2: Raise the temperature to 720 - 750 °C to melt the aluminum ingot, and add the metal powders in two batches: the first batch is silicon, copper, and zinc, and the second batch is magnesium, manganese, titanium, zirconium, chromium, and yttrium;

[0024] S3. After melting is completed, keep warm for 30 min, and the electromagnetic stirring frequency in the furnace is 20 Hz.

[0025] As a further optimized scheme of the present invention, the electromagnetic stirring in step three specifically includes:

[0026] S1. Apply a 20 kHz alternating magnetic field to the molten alloy and stir for 15 min;

[0027] S2. Adopt semi-continuous casting, control the cooling water flow rate to 50 L / min, and the cooling rate ≥ 50 °C / s;

[0028] S3. Spray nano-graphite emulsion on the surface of the ingot to prevent oxidation.

[0029] As a further optimized scheme of the present invention, the gradient homogenization treatment in step four specifically includes:

[0030] S1. The first stage: Heat the ingot to 450 °C at a rate of 10 °C / min and keep warm for 4 h;

[0031] S2. The second stage: Heat to 520 °C at a rate of 5 °C / min and keep warm for 2 h;

[0032] S3. The third stage: Force air-cool to room temperature, and the wind speed is 8 m / s.

[0033] As a further optimized scheme of the present invention, the multi-pass hot extrusion in step five specifically includes:

[0034] S1. Preheat the extrusion die to 480 - 500 °C, and set the extrusion cylinder pressure to 250 MPa;

[0035] S2. Extrude in 3 passes, and the deformation amount of each pass is 35%, 30%, and 25% respectively, and the total extrusion ratio is 12:1;

[0036] S3. Spray deionized water at 40 °C on the profile between each pass to cool it to below 300 °C.

[0037] As a further optimized scheme of the present invention, the double-stage solution treatment and aging in step six specifically includes:

[0038] S1. First-stage solution treatment: Keep warm at 535 °C for 1 h and then water quench, and the quenching transfer time ≤ 5 s;

[0039] S2. Second-stage solution treatment: Keep warm at 550 °C for 0.5 h and then perform secondary water quenching;

[0040] S3. Step-by-step aging: First keep warm at 120 °C for 8 h, and then raise the temperature to 160 °C and keep warm for 4 h.

[0041] As a further optimized scheme of the present invention, the micro-arc oxidation treatment in step seven specifically includes:

[0042] S1. Electrolyte preparation: sodium silicate 10 g / L, potassium dihydrogen phosphate 5 g / L, yttrium salt 0.1 g / L;

[0043] S2. Oxidation parameters: voltage 350 V, duty cycle 30%, treatment time 20 min;

[0044] S3. Post-oxidation sealing treatment: soak in deionized water at 90 °C for 30 min.

[0045] As a further optimized solution of the present invention, the detection and finishing in step eight specifically include:

[0046] S1. Ultrasonic flaw detection to detect internal defects, frequency 5 MHz;

[0047] S2. Laser calibration for dimensional deviation, accuracy ±0.05 mm;

[0048] S3. Surface spraying of an epoxy resin anti-rust layer, thickness 10 - 15 μm.

[0049] The above technical solution of the present invention has the following beneficial technical effects:

[0050] 1. Through the vacuum induction melting and electromagnetic stirring processes, the present invention avoids the formation of coarse secondary phases of alloying elements such as silicon, copper, and zinc during melting, refines the alloy structure, reduces the crack initiation points, thereby effectively improving the toughness of the material, making it less likely to break when subjected to impact, and ensuring the safety of the automotive sill beam during collision.

[0051] 2. By controlling the raw material ratio and various preparation process parameters, such as gradient homogenization treatment, double-stage solution treatment and aging, etc., the aluminum alloy profile of the present invention has comprehensive properties such as high strength, high elongation rate, and good corrosion resistance. The high strength can effectively withstand the impact force during the side collision of the vehicle, the high elongation rate enables the profile to better absorb energy during deformation, and the good corrosion resistance extends the service life of the sill beam, meeting the multi-faceted performance requirements of automotive manufacturing for the sill beam.

[0052] 3. Through micro-arc oxidation treatment, a 10 - 15 μm ceramic layer is formed on the surface of the profile. Combined with the surface spraying of an epoxy resin anti-rust layer, the surface hardness and corrosion resistance of the profile are improved. This not only prevents the profile from being corroded during use, but also further enhances its reliability in complex environments and reduces the safety risks caused by surface damage.

[0053] 4. During the preparation process, the multi-pass hot extrusion process can achieve high-quality standards for profiles in a single forming process by reasonably setting the extrusion temperature, extrusion ratio, and deformation amount per pass, reducing subsequent processing steps and straightening costs. At the same time, the precise control of the cooling water flow rate and cooling rate during the semi-continuous casting process, as well as the synergistic effects of processes such as electromagnetic stirring and gradient homogenization treatment, improve the quality of the ingot and reduce the rejection rate. In addition, in the efficient inspection and finishing process, advanced technologies such as ultrasonic flaw detection and laser calibration are used to quickly and accurately detect product defects and dimensional deviations, avoiding rework and waste caused by quality problems, thus effectively reducing production costs and improving overall production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The flowchart of a method for preparing a high-strength sill beam aluminum alloy profile proposed by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0056] Embodiment 1

[0057] As Figure 1 shown, a high-strength sill beam aluminum alloy profile proposed by the present invention, the raw material composition by weight includes:

[0058] 85 parts of aluminum ingot, 0.8 part of silicon, 0.6 part of magnesium, 0.3 part of copper, 0.2 part of zinc, 0.4 part of manganese, 0.05 part of titanium, 0.1 part of zirconium, 0.05 part of chromium, 0.02 part of yttrium.

[0059] A method for preparing a high-strength sill beam aluminum alloy profile, using the high-strength sill beam aluminum alloy profile as claimed in claim 1, comprising the following steps:

[0060] Step 1: Pretreatment of raw materials, crushing the aluminum ingot into 10 - 20 mm particles, and ball-milling the remaining metals;

[0061] Step 2: Vacuum induction melting, melting under the protection of inert gas for 30 minutes, and adding silicon, copper, and zinc;

[0062] Step 3: Electromagnetic stirring, applying a magnetic field with a frequency of 20 kHz for stirring for 15 minutes to eliminate compositional segregation;

[0063] Step 4: Gradient homogenization treatment. First, keep it at 450°C for 4 hours, and then heat it up to 520°C and keep it for 2 hours to eliminate the low-melting eutectic phase;

[0064] Step 5: Multi-pass hot extrusion. The extrusion temperature is 480 - 500°C, the extrusion ratio is 12:1, and the deformation per pass is less than 40%;

[0065] Step 6: Two-stage solution treatment and aging, which are divided into primary solution treatment, secondary solution treatment and step-by-step aging;

[0066] Step 7: Micro-arc oxidation treatment. The electrolyte contains sodium silicate and phosphate, the voltage is 350V, and a ceramic layer of 10 - 15μm is formed;

[0067] Step 8: Detection and finishing. Use instrument flaw detection to detect internal defects of the product.

[0068] In this embodiment, the raw material pretreatment in Step 1 specifically includes:

[0069] S1. Crush the aluminum ingot into particles of 10 - 20mm;

[0070] S2. Ball-mill the metal powders of silicon, magnesium, copper, zinc, manganese, titanium, zirconium, chromium, and yttrium until D50 ≤ 5μm;

[0071] S3. Screen the ball-milled powder through a 200-mesh sieve to remove agglomerates.

[0072] In this embodiment, the vacuum induction melting in Step 2 specifically includes:

[0073] S1. Place the aluminum ingot particles in a vacuum induction furnace, evacuate to 1×10-3Pa and then fill with argon to 0.5MPa;

[0074] S2. Heat up to 720 - 750°C to melt the aluminum ingot, and add the metal powders in two batches: the first batch is silicon, copper, and zinc, and the second batch is magnesium, manganese, titanium, zirconium, chromium, and yttrium;

[0075] S3. Keep it warm for 30 minutes after melting, and the electromagnetic stirring frequency in the furnace is 20Hz.

[0076] In this embodiment, the electromagnetic stirring in Step 3 specifically includes:

[0077] S1. Apply a 20kHz alternating magnetic field to the molten alloy and stir for 15 minutes;

[0078] S2. Adopt semi-continuous casting, control the cooling water flow rate to 50L / min, and the cooling rate ≥ 50°C / s;

[0079] S3. Spray nano-graphite emulsion on the surface of the ingot to prevent oxidation.

[0080] In this embodiment, the gradient homogenization treatment in step four specifically includes:

[0081] S1. First stage: The ingot is heated to 450 °C at a rate of 10 °C / min and held for 4 h;

[0082] S2. Second stage: It is heated to 520 °C at a rate of 5 °C / min and held for 2 h;

[0083] S3. Third stage: It is forced air-cooled to room temperature with a wind speed of 8 m / s.

[0084] In this embodiment, the multi-pass hot extrusion in step five specifically includes:

[0085] S1. The extrusion die is preheated to 480 - 500 °C, and the extrusion cylinder pressure is set at 250 MPa;

[0086] S2. It is extruded in 3 passes, and the deformation amount in each pass is 35%, 30%, and 25% respectively, with a total extrusion ratio of 12:1;

[0087] S3. The profile is sprayed with deionized water at 40 °C between each pass and cooled to below 300 °C.

[0088] In this embodiment, the double-stage solution treatment and aging in step six specifically includes:

[0089] S1. First-stage solution treatment: Hold at 535 °C for 1 h and then water quench, with the quenching transfer time ≤ 5 s;

[0090] S2. Second-stage solution treatment: Hold at 550 °C for 0.5 h and then perform secondary water quenching;

[0091] S3. Step-by-step aging: First hold at 120 °C for 8 h, and then raise the temperature to 160 °C and hold for 4 h.

[0092] In this embodiment, the micro-arc oxidation treatment in step seven specifically includes:

[0093] S1. Electrolyte preparation: Sodium silicate 10 g / L, potassium dihydrogen phosphate 5 g / L, yttrium salt 0.1 g / L;

[0094] S2. Oxidation parameters: Voltage 350 V, duty cycle 30%, treatment time 20 min;

[0095] S3. Post-oxidation sealing treatment: Immerse in deionized water at 90 °C for 30 min.

[0096] In this embodiment, the inspection and finishing in step eight specifically includes:

[0097] S1. Ultrasonic flaw detection to detect internal defects, with a frequency of 5 MHz;

[0098] S2. Laser calibration of dimensional deviation, with an accuracy of ±0.05 mm;

[0099] S3. Spray an epoxy resin anti-rust layer on the surface with a thickness of 10-15 μm.

[0100] Example 2

[0101] As Figure 1 shown, a high-strength sill beam aluminum alloy profile proposed by the present invention has the following raw material composition by weight:

[0102] 87 parts of aluminum ingot, 1 part of silicon, 0.9 part of magnesium, 0.5 part of copper, 0.4 part of zinc, 0.6 part of manganese, 0.08 part of titanium, 0.1 part of zirconium, 0.08 part of chromium, 0.05 part of yttrium.

[0103] A preparation method of a high-strength sill beam aluminum alloy profile, using the high-strength sill beam aluminum alloy profile as claimed in claim 1, comprises the following steps:

[0104] Step 1: Pretreatment of raw materials. Crush the aluminum ingot into 10-20 mm particles, and ball-mill the remaining metals.

[0105] Step 2: Vacuum induction melting. Melt under the protection of inert gas for 30 min, and add silicon, copper and zinc.

[0106] Step 3: Electromagnetic stirring. Apply a magnetic field with a frequency of 20 kHz and stir for 15 min to eliminate composition segregation.

[0107] Step 4: Gradient homogenization treatment. First, keep the temperature at 450 °C for 4 h, then raise the temperature to 520 °C and keep it for 2 h to eliminate the low-melting eutectic phase.

[0108] Step 5: Multi-pass hot extrusion. The extrusion temperature is 480-500 °C, the extrusion ratio is 12:1, and the deformation amount per pass is less than 40%.

[0109] Step 6: Double-stage solution treatment and aging, which are divided into primary solution treatment, secondary solution treatment and step-by-step aging.

[0110] Step 7: Micro-arc oxidation treatment. The electrolyte contains sodium silicate and phosphate, and the voltage is 350 V to form a 10-15 μm ceramic layer.

[0111] Step 8: Detection and finishing. Use an instrument to detect internal defects of the product by flaw detection.

[0112] In this embodiment, the pretreatment of raw materials in step 1 specifically includes:

[0113] S1. Crush the aluminum ingot into 10-20 mm particles;

[0114] S2. Ball-mill the metal powders of silicon, magnesium, copper, zinc, manganese, titanium, zirconium and chromium until D50 ≤ 5 μm;

[0115] S3. Sieving the milled powder through a 200-mesh sieve to remove agglomerates.

[0116] In this embodiment, the vacuum induction melting in step two specifically includes:

[0117] S1. Placing the aluminum ingot particles in a vacuum induction furnace, evacuating to 1×10-3 Pa and then filling with argon to 0.5 MPa;

[0118] S2. Heating to 720 - 750 °C to melt the aluminum ingot, and adding metal powders in two batches: the first batch is silicon, copper, and zinc, and the second batch is magnesium, manganese, titanium, zirconium, chromium, and yttrium;

[0119] S3. After melting, holding for 30 min, and the electromagnetic stirring frequency in the furnace is 20 Hz.

[0120] In this embodiment, the electromagnetic stirring in step three specifically includes:

[0121] S1. Applying a 20 kHz alternating magnetic field to the molten alloy and stirring for 15 min;

[0122] S2. Adopting semi-continuous casting, controlling the cooling water flow rate to 50 L / min, and the cooling rate ≥ 50 °C / s;

[0123] S3. Spraying nano-graphite emulsion on the surface of the ingot to prevent oxidation.

[0124] In this embodiment, the gradient homogenization treatment in step four specifically includes:

[0125] S1. The first stage: heating the ingot to 450 °C at a rate of 10 °C / min and holding for 4 h;

[0126] S2. The second stage: heating to 520 °C at a rate of 5 °C / min and holding for 2 h;

[0127] S3. The third stage: forced air cooling to room temperature, with a wind speed of 8 m / s.

[0128] In this embodiment, the multi-pass hot extrusion in step five specifically includes:

[0129] S1. Preheating the extrusion die to 480 - 500 °C and setting the extrusion cylinder pressure to 250 MPa;

[0130] S2. Extruding in 3 passes, with the deformation amount in each pass being 35%, 30%, and 25% respectively, and the total extrusion ratio being 12:1;

[0131] S3. Spraying deionized water at 40 °C on the profile between each pass to cool it below 300 °C.

[0132] In this embodiment, the double-stage solution treatment and aging in step six specifically include:

[0133] S1. Primary solution treatment: Keep at 535 °C for 1 h and then water quench, with the quenching transfer time ≤ 5 s;

[0134] S2. Secondary solution treatment: Keep at 550 °C for 0.5 h and then perform secondary water quenching;

[0135] S3. Step-by-step aging: First, keep at 120 °C for 8 h, and then heat up to 160 °C and keep for 4 h.

[0136] In this embodiment, the micro-arc oxidation treatment in Step 7 specifically includes:

[0137] S1. Electrolyte preparation: Sodium silicate 10 g / L, potassium dihydrogen phosphate 5 g / L, yttrium salt 0.1 g / L;

[0138] S2. Oxidation parameters: Voltage 350 V, duty cycle 30%, treatment time 20 min;

[0139] S3. Post-oxidation sealing treatment: Immerse in deionized water at 90 °C for 30 min.

[0140] In this embodiment, the detection and finishing in Step 8 specifically includes:

[0141] S1. Ultrasonic flaw detection to detect internal defects, with a frequency of 5 MHz;

[0142] S2. Laser calibration for dimensional deviation, with an accuracy of ±0.05 mm;

[0143] S3. Surface spraying of an epoxy resin anti-rust layer, with a thickness of 10 - 15 μm.

[0144] Example 3

[0145] As Figure 1 shown, a high-strength sill beam aluminum alloy profile proposed by the present invention, the raw material composition by weight includes:

[0146] 90 parts of aluminum ingot, 1.5 parts of silicon, 1.2 parts of magnesium, 0.8 parts of copper, 0.6 parts of zinc, 0.9 parts of manganese, 0.15 parts of titanium, 0.3 parts of zirconium, 0.1 part of chromium, 0.08 parts of yttrium.

[0147] A preparation method of a high-strength sill beam aluminum alloy profile, using the high-strength sill beam aluminum alloy profile as claimed in claim 1, includes the following steps:

[0148] Step 1: Pretreatment of raw materials, crush the aluminum ingot into 10 - 20 mm particles, and ball mill the remaining metals;

[0149] Step 2: Vacuum induction melting, melt under the protection of inert gas for 30 min, and add silicon, copper and zinc;

[0150] Step 3: Electromagnetic stirring, applying a magnetic field with a frequency of 20 kHz for stirring for 15 min to eliminate compositional segregation;

[0151] Step 4: Gradient homogenization treatment, first holding at 450 °C for 4 h, then heating up to 520 °C and holding for 2 h to eliminate the eutectic phase with low melting point;

[0152] Step 5: Multi-pass hot extrusion, extrusion temperature of 480 - 500 °C, extrusion ratio of 12:1, and the deformation amount per pass is less than 40%;

[0153] Step 6: Double-stage solution treatment and aging, including primary solution treatment, secondary solution treatment and step-by-step aging;

[0154] Step 7: Micro-arc oxidation treatment, the electrolyte contains sodium silicate and phosphate, voltage of 350 V, to generate a ceramic layer of 10 - 15 μm;

[0155] Step 8: Detection and finishing, using instrument flaw detection to detect internal defects of the product.

[0156] In this embodiment, the raw material pretreatment in Step 1 specifically includes:

[0157] S1. Crushing the aluminum ingot into particles of 10 - 20 mm;

[0158] S2. Ball-milling the metal powders of silicon, magnesium, copper, zinc, manganese, titanium, zirconium, chromium, and yttrium until D50 ≤ 5 μm;

[0159] S3. Screening the ball-milled powders through a 200-mesh sieve to remove agglomerates.

[0160] In this embodiment, the vacuum induction melting in Step 2 specifically includes:

[0161] S1. Placing the aluminum ingot particles in a vacuum induction furnace, evacuating to 1×10-3 Pa and then filling with argon to 0.5 MPa;

[0162] S2. Heating up to 720 - 750 °C to melt the aluminum ingot, adding the metal powders in two batches: the first batch is silicon, copper, and zinc, and the second batch is magnesium, manganese, titanium, zirconium, chromium, and yttrium;

[0163] S3. After melting, holding for 30 min, and the electromagnetic stirring frequency in the furnace is 20 Hz.

[0164] In this embodiment, the electromagnetic stirring in Step 3 specifically includes:

[0165] S1. Applying an alternating magnetic field of 20 kHz to the molten alloy and stirring for 15 min;

[0166] S2. Adopting semi-continuous casting, controlling the cooling water flow rate to 50 L / min, and the cooling rate ≥ 50 °C / s;

[0167] S3. Spray nano-graphite emulsion on the ingot surface to prevent oxidation.

[0168] In this embodiment, the gradient homogenization treatment in step four specifically includes:

[0169] S1. First stage: Heat the ingot to 450 °C at a rate of 10 °C / min and hold for 4 h.

[0170] S2. Second stage: Heat to 520 °C at a rate of 5 °C / min and hold for 2 h.

[0171] S3. Third stage: Force air-cool to room temperature with a wind speed of 8 m / s.

[0172] In this embodiment, the multi-pass hot extrusion in step five specifically includes:

[0173] S1. Preheat the extrusion die to 480 - 500 °C and set the extrusion cylinder pressure to 250 MPa.

[0174] S2. Extrude in 3 passes with deformation amounts of 35%, 30%, and 25% respectively for each pass, and the total extrusion ratio is 12:1; S3. Spray deionized water at 40 °C on the profile between each pass to cool it below 300 °C.

[0175] In this embodiment, the double-stage solution treatment and aging in step six specifically include:

[0176] S1. Primary solution treatment: Hold at 535 °C for 1 h and then water quench, with the quenching transfer time ≤ 5 s.

[0177] S2. Secondary solution treatment: Hold at 550 °C for 0.5 h and then perform secondary water quenching.

[0178] S3. Step-by-step aging: First hold at 120 °C for 8 h, and then heat up to 160 °C and hold for 4 h.

[0179] In this embodiment, the micro-arc oxidation treatment in step seven specifically includes:

[0180] S1. Electrolyte preparation: Sodium silicate 10 g / L, potassium dihydrogen phosphate 5 g / L, yttrium salt 0.1 g / L.

[0181] S2. Oxidation parameters: Voltage 350 V, duty cycle 30%, treatment time 20 min.

[0182] S3. Post-oxidation sealing treatment: Immerse in deionized water at 90 °C for 30 min.

[0183] In this embodiment, the inspection and finishing in step eight specifically include:

[0184] S1. Use ultrasonic flaw detection to detect internal defects, with a frequency of 5 MHz.

[0185] S2. Laser calibrates the dimensional deviation with an accuracy of ±0.05 mm;

[0186] S3. Spray an epoxy resin anti-rust layer on the surface with a thickness of 10 - 15 μm.

[0187] Select the finished products of Example 1, Example 2, and Example 3 for performance testing, and the results are as follows:

[0188]

[0189]

[0190] The specific working principle of the present invention is as follows:

[0191] First, for the raw material pretreatment, the aluminum ingot is crushed, and the remaining metals are ball-milled and sieved, making the raw material particles fine and uniform, laying a foundation for subsequent uniform melting. The vacuum induction melting is carried out under the protection of inert gas, controlling the temperature and melting time, and adding metal powders in batches to ensure the uniform mixing of alloy components and reduce the mixing of impurities. The electromagnetic stirring applies a 20 kHz magnetic field for 15 min, which can effectively eliminate compositional segregation and make the alloy components more uniform;

[0192] For the gradient homogenization treatment, it is first kept at 450 °C for 4 h, and then heated to 520 °C and kept for 2 h. By keeping at different temperature stages, the low-melting eutectic phase is eliminated and the alloy structure is optimized. The multi-pass hot extrusion is carried out under the conditions of 480 - 500 °C, an extrusion ratio of 12:1, and a deformation amount per pass less than 40%, enabling the alloy to obtain good plasticity and a dense organizational structure. For the double-stage solution and aging, the first-stage solution is kept at 535 °C for 1 h and then water-quenched, the second-stage solution is kept at 550 °C for 0.5 h and then doubly water-quenched, and then step-by-step aging is carried out to further improve the strength and hardness of the alloy;

[0193] For the micro-arc oxidation treatment, in the electrolyte containing sodium silicate and phosphate, a voltage of 350 V is applied to generate a ceramic layer to improve the surface performance. Finally, the inspection and finishing detect internal defects through flaw detection, laser calibrate the dimensional deviation, and spray the anti-rust layer to ensure the product quality and reliability. These processes cooperate with each other. From raw material treatment to tissue optimization, then to performance improvement and quality inspection, finally, a high-strength sill beam aluminum alloy profile meeting the requirements of automobile manufacturing is prepared.

[0194] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modification examples falling within the scope and boundary of the appended claims, or equivalent forms of such scope and boundary.

Claims

1. An aluminum alloy profile for a high-strength threshold beam, characterized in that, Its raw material composition includes, by weight: 85-90 parts of aluminum ingot, 0.8-1.5 parts of silicon, 0.6-1.2 parts of magnesium, 0.3-0.8 parts of copper, 0.2-0.6 parts of zinc, 0.4-0.9 parts of manganese, 0.05-0.15 parts of titanium, 0.1-0.3 parts of zirconium, 0.05-0.1 parts of chromium, 0.02-0.08 parts of yttrium.

2. A preparation method of an aluminum alloy profile for a high-strength door sill beam, using the aluminum alloy profile for a high-strength door sill beam as claimed in claim 1, characterized in that, It includes the following steps: Step 1: Pretreatment of raw materials. The aluminum ingot is crushed into particles of 10-20 mm, and the remaining metals are ball-milled. Step 2: Vacuum induction melting. Melting is carried out under the protection of inert gas for 30 min, and silicon, copper and zinc are added. Step 3: Electromagnetic stirring. A magnetic field with a frequency of 20 kHz is applied for stirring for 15 min to eliminate compositional segregation. Step 4: Gradient homogenization treatment. First, it is kept at 450 °C for 4 h, and then heated to 520 °C and kept for 2 h to eliminate the low-melting eutectic phase. Step 5: Multi-pass hot extrusion. The extrusion temperature is 480-500 °C, the extrusion ratio is 12:1, and the deformation amount per pass is less than 40%. Step 6: Two-stage solution treatment and aging, which are divided into primary solution treatment, secondary solution treatment and step-by-step aging. Step 7: Micro-arc oxidation treatment. The electrolyte contains sodium silicate and phosphate, the voltage is 350 V, and a ceramic layer of 10-15 μm is formed. Step 8: Detection and finishing. Instruments are used for flaw detection to detect internal defects of the product.

3. The preparation method of a high-strength threshold beam aluminum alloy profile according to claim 2, characterized in that, The pretreatment of raw materials in Step 1 specifically includes: S1. The aluminum ingot is crushed into particles of 10-20 mm. S2. The metal powders of silicon, magnesium, copper, zinc, manganese, titanium, zirconium and chromium are ball-milled to D50≤5 μm. S3. The ball-milled powder is screened through a 200-mesh sieve to remove agglomerates.

4. The preparation method of an aluminum alloy profile for a high-strength door sill beam according to claim 3, characterized in that, The vacuum induction melting in Step 2 specifically includes: S1. The aluminum ingot particles are placed in a vacuum induction furnace, evacuated to 1×10-3 Pa and then filled with argon to 0.5 MPa. S2. It is heated to 720-750 °C to melt the aluminum ingot, and the metal powders are added in two batches: the first batch is silicon, copper and zinc, and the second batch is magnesium, manganese, titanium, zirconium and chromium. S3. After melting, it is kept warm for 30 min, and the electromagnetic stirring frequency in the furnace is 20 Hz.

5. The preparation method of an aluminum alloy profile for a high-strength sill beam according to claim 4, characterized in that, The electromagnetic stirring in Step 3 specifically includes: S1. A 20-kHz alternating magnetic field is applied to the molten alloy for stirring for 15 min. S2. Semi-continuous casting is adopted, and the cooling water flow rate is controlled at 50 L / min, and the cooling rate is ≥50 °C / s. S3. The surface of the ingot is sprayed with nano-graphite emulsion to prevent oxidation.

6. The preparation method of an aluminum alloy profile for a high-strength threshold beam according to claim 5, characterized in that, The gradient homogenization treatment in Step 4 specifically includes: S1. The first stage: The ingot is heated to 450 °C at a rate of 10 °C / min and kept for 4 h. S2. The second stage: It is heated to 520 °C at a rate of 5 °C / min and kept for 2 h. S3. The third stage: Forced air cooling to room temperature, and the wind speed is 8 m / s.

7. The preparation method of a high-strength threshold beam aluminum alloy profile according to claim 6, characterized in that, The multi-pass hot extrusion in Step 5 specifically includes: S1. The extrusion die is preheated to 480-500 °C, and the extrusion cylinder pressure is set at 250 MPa. S2. Extrusion is carried out in 3 passes, and the deformation amounts per pass are 35%, 30% and 25% respectively, and the total extrusion ratio is 12:

1. S3. Deionized water at 40 °C is sprayed on the profile between each pass to cool it below 300 °C.

8. The preparation method of an aluminum alloy profile for a high-strength threshold beam according to claim 7, characterized in that, The two-stage solution treatment and aging in Step 6 specifically includes: S1. Primary solution treatment: Heat at 535°C for 1 hour and then water quench, with the quenching transfer time ≤ 5 s; S2. Secondary solution treatment: Heat at 550°C for 0.5 hour and then perform secondary water quenching; S3. Step-by-step aging: First, heat at 120°C for 8 hours, then raise the temperature to 160°C and heat for 4 hours.

9. The preparation method of an aluminum alloy profile for a high-strength sill beam according to claim 8, characterized in that, The micro-arc oxidation treatment in Step 7 specifically includes: S1. Electrolyte preparation: Sodium silicate 10 g / L, potassium dihydrogen phosphate 5 g / L, yttrium salt 0.1 g / L; S2. Oxidation parameters: Voltage 350 V, duty cycle 30%, treatment time 20 min; S3. Post-oxidation sealing treatment: Immerse in deionized water at 90°C for 30 min.

10. The preparation method of an aluminum alloy profile for a high-strength sill beam according to claim 9, characterized in that, The inspection and finishing in Step 8 specifically include: S1. Ultrasonic flaw detection to detect internal defects, with a frequency of 5 MHz; S2. Laser calibration of dimensional deviation, with an accuracy of ±0.05 mm; S3. Surface spraying of an epoxy resin anti-rust layer with a thickness of 10 - 15 μm.

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