Extrusion production process of ultra-high strength pedestrian protection beam profile for automobile

Abstract

An extrusion production process of an ultra-high strength pedestrian protection beam profile for automobiles belongs to the technical field of aluminum alloy processes, and through reasonable design of a 7-series component, control of ingot melting and homogenization temperature, adjustment and repair of an extrusion die and an extrusion equipment, strict regulation and control of extrusion process parameters, and through a large number of test explorations of a high-quality aging system to meet the ultra-high strength standard requirements of the profile, the yield strength of the prepared ultra-high strength pedestrian protection beam profile for automobiles can reach 310-330 MPa, the tensile strength is greater than 370 MPa, and the elongation is greater than 15% of a single-cavity thin-wall ultra-high strength pedestrian protection beam profile product for automobiles.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy processing technology, specifically relating to an extrusion production process for ultra-high strength pedestrian protection beam profiles for automobiles. Background Technology

[0002] In recent years, with the increasingly widespread application of extruded aluminum alloy profiles, market demand has been increasing year by year, thus placing higher demands on the product quality standards of extruded aluminum alloys. However, currently, over 80% of extruded aluminum alloy products are made using 6-series aluminum alloys, which have good formability. But 6-series aluminum alloy profiles have relatively low mechanical strength, which can no longer meet the relevant requirements of high-end automotive brands both domestically and internationally. To adapt to market development, a process technology for producing ultra-high strength 7-series extruded aluminum alloy profiles has been developed. The production of ultra-high strength thin-walled hollow profiles for automobiles using 7-series aluminum alloys is a technological bottleneck in the industry. To improve the extrudability of 7-series aluminum alloys, 7108 aluminum alloy is used for extrusion. This alloy not only has good formability but also maintains ultra-high strength, making it one of the best materials for ultra-high strength pedestrian protection beams for automobiles. By adjusting various aspects of the extrusion process, including chemical composition, ingot homogenization temperature, die structure, extrusion process parameters, and aging regime, a technological breakthrough has been achieved by successfully developing an extrusion production process technology suitable for ultra-high strength pedestrian protection beam profiles for automobiles. Summary of the Invention

[0003] To address the problems existing in the prior art, the purpose of this invention is to disclose an extrusion production process for ultra-high strength pedestrian protection beam profiles for automobiles. Based on the European standard EN573-3, the composition of the 7108 alloy is finely adjusted to ensure the mechanical properties of the profile while improving the fluidity of the metal during the extrusion process. This results in more uniform metal flow in the die, reducing extrusion pressure and thus improving the extrudability of hard 7-series extruded aluminum alloys, solving the industry problem of difficult extrusion molding of 7-series aluminum alloys. By adjusting the casting ingot homogenization process, improving the die structure, ensuring uniform metal flow velocity throughout the profile, and strictly monitoring the production process, ultra-high strength pedestrian protection beam profiles for automobiles with an outer circle diameter of φ65-68mm, a single-cavity structure, a wall thickness of 2-3mm, a yield strength of 320MPa, a tensile strength greater than 370MPa, and an elongation greater than 15% can be efficiently extruded. The profile cross-section is shown below. Figure 1 As shown.

[0004] In terms of composition design: Si: ≤0.07%, Fe: ≤0.05%, Cu: ≤0.04%, Mn: ≤0.05%, Mg: 0.90%~1.30%, Cr: ≤0.08%, Zn: 4.50%~4.90%, other individual impurity elements ≤0.05%, total impurity content ≤0.15%, balance is Al. The Mg2Si content in the composition needs to be controlled within the range of 0.7%-1.0%, and the excess Mg content should be ≤0.3%. This composition design greatly improves the extrudability of 7-series aluminum alloys while ensuring mechanical properties.

[0005] Regarding casting control: Ingots are produced using a semi-continuous casting method. During the casting process, foam ceramic filtration is employed, and Al-Ti-B wire, a micro-grain refiner, is used to refine the grains. The amount of scrap aluminum added is controlled to ≤15%. The scrap aluminum originates from substandard aluminum products in the aluminum alloy industrial materials, aluminum alloy building materials, and rail transportation and automotive aluminum alloy profiles, involving 7-series and 2-series aluminum alloys. The amount of scrap aluminum added for these industrial and / or transportation applications should be controlled within the range of ≤15%.

[0006] Melting temperature 680℃-740℃, refining temperature 700℃-740℃, refining agent dosage 2.69-3.0kg / TAl;

[0007] The slag content of the ingot must meet the Class II requirements in GB / T32186-2015. Hydrogen element: 0.15-0.19 ml / 100g.

[0008] Regarding the homogenization of the casting rods: High-temperature, long-term homogenization is applied to the casting rods, with a process of 470℃-500℃ and holding for 12-16 hours. This improves the hot deformation plasticity of the casting rods, eliminates internal stress in the ingot, and eliminates dendritic segregation and non-equilibrium brittle crystalline phases generated during the melting and cooling process inside the casting rod. It also promotes the dissolution of non-equilibrium solidified phases in the ingot and ensures a uniform, fine, and dispersed distribution of reinforcing phases such as MgZn2, Al2Mg2Zn3, CuMgAl2, and (FeMn)Al6, thereby improving the mechanical properties of the extruded profiles.

[0009] In terms of mold design: To reduce the breakthrough pressure during extrusion and improve mold life, the angle between the conical surface of the flow divider and the mold axis is 3°-5°. Arc, arch, and stepped flow divider bridges are used, with a 30° slope, which reduces the pressure area of ​​the flow divider bridge and lowers the extrusion stress on it. A butterfly-shaped welding chamber structure is adopted. Figure 3 This eliminates the metal flow resistance at the junction of the welding chamber edge and the die plane, increases the material flow rate, and improves the extrudability of the metal while correspondingly enhancing the welding performance of the profile. Reducing the working band width from 7mm to below 4mm ensures excellent profile surface quality and dimensional accuracy while achieving ultra-high mechanical properties. The extrusion die manufacturing flowchart is shown below. Figure 2As shown.

[0010] In terms of extrusion process: A 1250T horizontal extrusion press is used to produce ultra-high strength pedestrian protection beam profiles for automobiles with an outer diameter of φ65-68mm and a wall thickness of 2-3mm. 490mm short ingots are used for production, with the breakthrough pressure controlled between 10-12MPa. Water cooling is used for quenching, with the quenching device moved 280-350mm forward from the die exit position. The cooling rate is above 95℃ / min. This process simultaneously meets ultra-high standard dimensional requirements and high-precision mechanical property standards. The die temperature is controlled at 450℃-500℃, the extrusion ingot temperature at 470℃-490℃, and the profile exit temperature at 480℃-500℃. The extrusion speed is 6-8m / min. In the aging furnace, the distance between two samples is >50mm, and the bottom distance from the sample is >30mm. The aging regime is 110℃×5h + 125℃×9h.

[0011] The beneficial effects of this invention are:

[0012] Currently, pedestrian protection beam profiles for automobiles are characterized by regular shapes and relatively low mechanical performance standards, all being 6-series aluminum alloy products. These no longer meet the aluminum requirements of high-end traditional and new energy vehicles. By rationally designing 7-series compositions, controlling ingot melting and homogenization temperatures, adjusting extrusion dies and equipment, and strictly controlling extrusion process parameters, a superior aging process has been developed through extensive experimentation to meet the ultra-high strength standards for these profiles. This results in single-cavity, thin-walled ultra-high strength pedestrian protection beam profiles for automobiles with yield strengths reaching 310-330 MPa, tensile strengths exceeding 370 MPa, and elongation exceeding 15%. Attached Figure Description

[0013] Figure 1 Profile cross-section drawing;

[0014] Figure 2 Flowchart of extrusion die manufacturing process;

[0015] Figure 3 Images of the extrusion die, showing the upper and lower dies;

[0016] Figure 4 Metallographic structure diagram of the profile in Example 1;

[0017] Figure 5 Results of intergranular corrosion performance test in Example 1;

[0018] Figure 6 Metallographic structure diagram of the profile in Example 2;

[0019] Figure 7 Results of intergranular corrosion performance test in Example 2;

[0020] Figure 8Metallographic structure diagram of the profile in Example 3;

[0021] Figure 9 Results of intergranular corrosion performance test in Example 3. Detailed Implementation

[0022] In the following embodiments, in order to reduce the breakthrough pressure during the extrusion process and improve the service life of the mold, the cone surface of the mold diversion hole is designed to have an angle of 3°-5° with the mold axis, and a circular arc, circular arch, or stepped diversion bridge is adopted, with a diversion bridge slope of 30°.

[0023] Example 1

[0024] An extrusion process for 7-series aluminum alloy automotive anti-collision beam profiles includes the following steps:

[0025] 1. Composition: Test equipment: ARL-3460 direct-reading spectrometer. Test method: GB / T7999-2015 Direct-reading photoelectric emission spectrometry analysis method for aluminum and aluminum alloys.

[0026] content% 0.02 0.01 0.02 0.03 1.26 0.04 4.79 0.05 margin

[0027] 2. Melting and Casting Process: Melting temperature 680℃-720℃, refining temperature 700℃-720℃, refining agent dosage 2.8kg / TAl, waste material addition not allowed to exceed 10%, slag content of ingots must meet the secondary requirements in GB / T32186-2015. Hydrogen element 0.15ml / 100g. Homogenization treatment temperature 470℃, holding time 14h.

[0028] 3. Mold design: adopts arc, arch, and stepped flow divider bridge, with a working belt width of 4mm.

[0029] 4. Extrusion Process: A 1250T horizontal extrusion press is used to produce extruded materials with an outer diameter of φ67mm and a wall thickness of 2.2mm. 490mm short ingots are used for production. The breakthrough pressure is 10MPa. Water cooling is used for quenching. The quenching device is 300mm from the die outlet. The cooling rate is 97℃ / min. The die temperature is 466℃, the extruded ingot temperature is 475℃, and the profile outlet temperature is 488℃. The extrusion speed is 6m / min. In the aging furnace, the distance between two samples is 70mm, and the bottom is 40mm from the sample. The aging regime is 110℃×5h + 125℃×9h.

[0030] 5. Mechanical Properties: Testing Equipment: AG-X 100KN Electronic Universal Testing Machine. Testing Standard: GB / T6892-2015 General Industrial Aluminum and Aluminum Alloy Extruded Profiles. Testing Method: GB / T16865-2013 Tense Test Specimens and Methods for Wrought Aluminum, Magnesium and Their Alloys Processed Products.

[0031] Table 1 Mechanical property results

[0032]

[0033]

[0034] 6. High-magnification microstructure: Testing equipment: AXIO universal research-grade inverted materials microscope. Testing standard: GB / T6892-2015 General industrial aluminum and aluminum alloy extruded profiles. Testing method: GB / T3246.1-2012 Deformed aluminum and aluminum alloy products - Microstructure inspection methods - Part 1: Microstructure inspection methods.

[0035] Standard requirement: The tissue must not be overheated;

[0036] Test results: High-magnification metallographic microstructure of the profile ( Figure 4 I have never seen it burned;

[0037] Conclusion: Qualified.

[0038] 7. Fusion Joint Test: Testing Equipment: Aluminum Profile Compression Testing Machine. Testing Standard: GB / T6892-2015 General Industrial Aluminum and Aluminum Alloy Extruded Profiles. Testing Method: GB / T32790-2016 Test Method for Welding Performance of Extruded Welds in Aluminum and Aluminum Alloys.

[0039] Table 2. Fusion Joint Test

[0040]

[0041] 8. Low-magnification test: The test equipment uses an alkaline corrosive solution. Test standard: GB / T6892-2015 General industrial aluminum and aluminum alloy extruded profiles. Test method: GB / T3246.2-2012 Deformed aluminum and aluminum alloy products - Microstructure inspection methods - Part 2: Low-magnification microstructure inspection methods.

[0042] Table 3 Low-magnification tissue test

[0043]

[0044] 9. Bending performance test: Test equipment: AG-X 100KN electronic universal testing machine. Test standard: VDA238-100 Test Specification for Bending Test of Metallic Materials (Plate).

[0045] Table 4. Bending performance test results

[0046]

[0047]

[0048] 10. Exfoliation Corrosion Performance Test: The testing equipment is a digital display constant temperature water bath. Test standard: GB / T22639-2008 Exfoliation Corrosion Test Method for Aluminum Alloy Processed Products.

[0049] Table 5. Exfoliation Corrosion Test

[0050]

[0051] 11. Intergranular corrosion test: Test equipment: AXIO universal research-grade inverted materials microscope. Test standard: ISO 14846 Method B.

[0052] Test results: Intergranular corrosion depth 151.19 micrometers ( Figure 5 );

[0053] Conclusion: Qualified.

[0054] Example 2

[0055] An extrusion process for 7-series aluminum alloy automotive anti-collision beam profiles includes the following steps:

[0056] 1. Composition: Test equipment: ARL-3460 direct-reading spectrometer. Test method: GB / T7999-2015 Direct-reading photoelectric emission spectrometry analysis method for aluminum and aluminum alloys.

[0057] content% 0.03 0.01 0.01 0.04 1.28 0.03 4.82 0.05 margin

[0058] 2. Melting and Casting Process: Melting temperature 690℃-730℃, refining temperature 710℃-730℃, refining agent dosage 3.0kg / TAl, waste addition not allowed to exceed 8%, slag content of ingots must meet the secondary requirements in GB / T32186-2015. Hydrogen element 0.17ml / 100g. Homogenization treatment temperature is 480℃, holding time is 15h.

[0059] 3. Mold design: adopts arc, arch, and stepped flow divider bridge, with a working belt width of 3.5mm.

[0060] 4. Extrusion Process: A 1250T horizontal extrusion press is used to produce extruded materials with an outer diameter of φ66mm and a wall thickness of 2.7mm. 490mm short ingots are used for production. The breakthrough pressure is 11MPa. Water cooling is used for quenching. The quenching device is 290mm from the die outlet. The cooling rate is 107℃ / min. The die temperature is 470℃, the extruded ingot temperature is 480℃, and the profile outlet temperature is 485℃. The extrusion speed is 7m / min. In the aging furnace, the distance between two samples is 75mm, and the bottom is 45mm from the sample. The aging regime is 110℃×5h + 125℃×9h.

[0061] 5. Mechanical Properties: Testing Equipment: AG-X 100KN Electronic Universal Testing Machine. Testing Standard: GB / T6892-2015 General Industrial Aluminum and Aluminum Alloy Extruded Profiles. Testing Method: GB / T16865-2013 Tense Test Specimens and Methods for Wrought Aluminum, Magnesium and Their Alloys Processed Products.

[0062] Table 6 Mechanical property results

[0063]

[0064] 6. High-magnification microstructure: Testing equipment: AXIO universal research-grade inverted materials microscope. Testing standard: GB / T6892-2015 General industrial aluminum and aluminum alloy extruded profiles. Testing method: GB / T3246.1-2012 Deformed aluminum and aluminum alloy products - Microstructure inspection methods - Part 1: Microstructure inspection methods.

[0065] Standard requirement: The tissue must not be overheated;

[0066] Test results: High-magnification metallographic microstructure of the profile ( Figure 6 I have never seen it burned;

[0067] Conclusion: Qualified.

[0068] 7. Fusion Joint Test: Testing Equipment: Aluminum Profile Compression Testing Machine. Testing Standard: GB / T6892-2015 General Industrial Aluminum and Aluminum Alloy Extruded Profiles. Testing Method: GB / T32790-2016 Test Method for Welding Performance of Extruded Welds in Aluminum and Aluminum Alloys.

[0069] Table 7. Fusion Joint Test

[0070]

[0071] 8. Low-magnification test: The test equipment uses an alkaline corrosive solution. Test standard: GB / T6892-2015 General industrial aluminum and aluminum alloy extruded profiles. Test method: GB / T3246.2-2012 Deformed aluminum and aluminum alloy products - Microstructure inspection methods - Part 2: Low-magnification microstructure inspection methods.

[0072] Table 8 Low-magnification tissue test

[0073]

[0074] 9. Bending performance test: Test equipment: AG-X 100KN electronic universal testing machine. Test standard: VDA238-100 Test Specification for Bending Test of Metallic Materials (Plate).

[0075] Table 9 Bending Performance Test Results

[0076]

[0077] 10. Exfoliation Corrosion Performance Test: The testing equipment is a digital display constant temperature water bath. Test standard: GB / T22639-2008 Exfoliation Corrosion Test Method for Aluminum Alloy Processed Products.

[0078] Table 10 Exfoliation Corrosion Test

[0079]

[0080] 11. Intergranular corrosion test: Test equipment: AXIO universal research-grade inverted materials microscope. Test standard: ISO 14846 Method B.

[0081] Test results: No intergranular corrosion depth ( Figure 7 );

[0082] Conclusion: Qualified.

[0083] Example 3

[0084] An extrusion process for 7-series aluminum alloy automotive anti-collision beam profiles includes the following steps:

[0085] 1. Composition: Test equipment: ARL-3460 direct-reading spectrometer. Test method: GB / T7999-2015 Direct-reading photoelectric emission spectrometry analysis method for aluminum and aluminum alloys.

[0086] content% 0.05 0.02 0.01 0.02 1.26 0.02 4.85 0.05 margin

[0087] 2. Melting and Casting Process: Melting temperature 690℃-740℃, refining temperature 720℃-740℃, refining agent dosage 2.69kg / TAl, waste addition not allowed to exceed 9%, slag content of ingots must meet the secondary requirements in GB / T32186-2015. Hydrogen element 0.19ml / 100g. Homogenization treatment temperature is 490℃, holding time is 16h.

[0088] 3. Mold design: adopts arc, arch, and stepped flow divider bridge, with a working belt width of 3.3mm.

[0089] 4. Extrusion Process: A 1250T horizontal extrusion press is used to produce extruded materials with an outer diameter of φ68mm and a wall thickness of 2.9mm. 490mm short ingots are used for production. The breakthrough pressure is 12MPa. Water cooling is used for quenching. The quenching device is 310mm from the die outlet. The cooling rate is 103℃ / min. The die temperature is 480℃, the extruded ingot temperature is 490℃, and the profile outlet temperature is 499℃. The extrusion speed is 8m / min. In the aging furnace, the distance between two samples is 80mm, and the bottom is 50mm from the sample. The aging regime is 110℃×5h + 125℃×9h.

[0090] 5. Mechanical Properties: Testing Equipment: AG-X 100KN Electronic Universal Testing Machine. Testing Standard: GB / T6892-2015 General Industrial Aluminum and Aluminum Alloy Extruded Profiles. Testing Method: GB / T16865-2013 Tense Test Specimens and Methods for Wrought Aluminum, Magnesium and Their Alloys Processed Products.

[0091] Table 11 Mechanical property results

[0092]

[0093] 6. High-magnification microstructure: Testing equipment: AXIO universal research-grade inverted materials microscope. Testing standard: GB / T6892-2015 General industrial aluminum and aluminum alloy extruded profiles. Testing method: GB / T3246.1-2012 Deformed aluminum and aluminum alloy products - Microstructure inspection methods - Part 1: Microstructure inspection methods.

[0094] Standard requirement: The tissue must not be overheated;

[0095] Test results: High-magnification metallographic microstructure of the profile ( Figure 8 I have never seen it burned;

[0096] Conclusion: Qualified.

[0097] 7. Fusion Joint Test: Testing Equipment: Aluminum Profile Compression Testing Machine. Testing Standard: GB / T6892-2015 General Industrial Aluminum and Aluminum Alloy Extruded Profiles. Testing Method: GB / T32790-2016 Test Method for Welding Performance of Extruded Welds in Aluminum and Aluminum Alloys.

[0098] Table 12 Fusion Joint Test

[0099]

[0100] 8. Low-magnification test: The test equipment uses an alkaline corrosive solution. Test standard: GB / T6892-2015 General industrial aluminum and aluminum alloy extruded profiles. Test method: GB / T3246.2-2012 Deformed aluminum and aluminum alloy products - Microstructure inspection methods - Part 2: Low-magnification microstructure inspection methods.

[0101] Table 13 Low-magnification tissue test

[0102]

[0103] 9. Bending performance test: Test equipment: AG-X 100KN electronic universal testing machine. Test standard: VDA238-100 Test Specification for Bending Test of Metallic Materials (Plate).

[0104] Table 14 Bending Performance Test Results

[0105]

[0106] 10. Exfoliation Corrosion Performance Test: The testing equipment is a digital display constant temperature water bath. Test standard: GB / T22639-2008 Exfoliation Corrosion Test Method for Aluminum Alloy Processed Products.

[0107] Table 15 Exfoliation Corrosion Test

[0108]

[0109] 11. Intergranular corrosion test: Test equipment: AXIO universal research-grade inverted materials microscope. Test standard: ISO 14846 Method B.

[0110] Test results: No intergranular corrosion depth ( Figure 9 );

[0111] Conclusion: Qualified.

Claims

1. A manufacturing process for extruding ultra-high strength pedestrian protection beam profiles for automobiles, characterized in that, Includes the following steps: Composition design: Si: ≤0.07%, Fe: ≤0.05%, Cu: ≤0.04%, Mn: ≤0.05%, Mg: 0.90%~1.30%, Cr: ≤0.08%, Zn: 4.50%~4.90%, other individual impurity elements ≤0.05%, total impurity content ≤0.15%, balance is Al, the Mg2Si content in the composition is controlled within the range of 0.7%-1.0%, and the excess Mg content ≤0.3%; Melting and casting control: Ingots are produced using a semi-continuous casting method. Foam ceramic filtration is used during the casting process, and Al-Ti-B wire, a micro-grain refiner, is used to refine the grains. The amount of scrap aluminum added is controlled to be ≤15%. Homogenization of casting rods: High-temperature and long-time homogenization of casting rods is carried out at 470℃-500℃ for 12-16 hours. Mold design: The angle between the conical surface of the flow divider and the mold axis is 3°-5°. The flow divider bridge adopts arc, arch, or stepped design with a slope of 30°. The working zone width is less than 4mm. Extrusion process: 490mm short ingots are used, with the breakthrough pressure controlled between 10-12MPa. Water cooling is used for quenching, and the quenching device is moved forward 280-350mm from the die outlet position. The cooling rate is above 95℃ / min, the die temperature is controlled at 450℃-500℃, the extrusion ingot temperature is controlled at 470℃-490℃, and the profile outlet temperature is controlled within the range of 480℃-500℃. The extrusion speed is 6-8m / min. In the extrusion process, the distance between the two samples in the aging furnace is >50mm, and the bottom distance from the sample is >30mm. The aging regime is 110℃×5h+125℃×9h. The specifications of the generated product are: circumscribed circle diameter Φ65-68mm, single-cavity structure, and wall thickness of 2-3mm.

2. The extrusion production process for ultra-high strength pedestrian protection beam profiles for automobiles according to claim 1, characterized in that, The resulting ultra-high strength pedestrian protection beam profile for automobiles has a yield strength of 320MPa, a tensile strength greater than 370MPa, and an elongation greater than 15%.

3. The extrusion production process for ultra-high strength pedestrian protection beam profiles for automobiles according to claim 1, characterized in that, In the casting process, the melting temperature is controlled at 680℃-740℃, the refining temperature is controlled at 700℃-740℃, the refining agent dosage is 2.69-3.0kg / TAl, and the hydrogen element dosage is 0.15-0.19ml / 100g.

Images