SD61 aluminum alloy medium plate production process

Abstract

The invention discloses a production process of an SD61 aluminum alloy medium plate, and particularly relates to the field of aluminum alloy material processing, and the production process comprises the specific preparation steps of component design, casting, cast ingot soaking, hot rolling, solution treatment, stretching, aging, finished product sawing and packaging. The content of key elements is adjusted on the basis of the 6061 aluminum alloy, and the fluidity and the thermal stability are enhanced by setting the content of Si; the strength and the corrosion resistance are improved by setting the content of Mg; fe is lower than 0.3%, so that the formation of impurity phases can be reduced; the device is particularly suitable for production of wide plates with the thickness of 45mm and 115mm and the width of more than 2200mm; according to the process, through component optimization, casting control, heat treatment and machining process improvement, the mechanical property, dimensional stability and corrosion resistance of the aluminum alloy plate are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy material processing, and more particularly to a production process of SD61 aluminum alloy medium and thick plates. Background Art

[0002] Aluminum alloy medium and thick plates have important applications in mold manufacturing, aerospace, automotive, and other fields, and their performance directly affects the precision, lifespan, and reliability of the final product. Traditional 6061 aluminum alloy (such as 6061-T651) was once the mainstream material for mold manufacturing due to its good processing properties and moderate strength. However, as modern industry continues to demand higher mold performance, traditional 6061 aluminum alloy has gradually exposed the following technical bottlenecks: 1. Inadequate mechanical properties: Conflict between strength and plasticity: Ordinary 6061-T651 sheet typically has a tensile strength of 290-310 MPa, a yield strength of 250-270 MPa, and an elongation of only approximately 9%. When subjected to high loads or complex stresses, it is prone to plastic deformation or fracture, making it difficult to meet the dual requirements of high strength and high toughness for large molds (such as automotive panel molds and die-casting molds). Insufficient hardness: The Brinell hardness (HBW) is 90-100, which causes the mold surface to wear easily during long-term use, affecting processing accuracy. 2. Significant deformation after processing: Residual stress issues: In traditional production processes, the stretching amount is generally less than 2%, making it difficult to completely eliminate the residual stress within the plate. After deep machining (such as milling and EDM), the residual stress release causes deformation, and the plate flatness fluctuation can reach 2-3mm / m. In severe cases, multiple corrections are required, increasing production costs; Poor dimensional stability: Especially in the production of wide (≥2200mm) and thick plates (≥45mm), the temperature gradient during hot rolling and quenching can easily cause plate warping, requiring frequent adjustment of process parameters during subsequent processing; 3. Corrosion Resistance Defects: Influence of Impurity Elements: Traditional 6061 aluminum alloy has a high Fe content (≤0.7%), which easily forms coarse Al-Fe-Si intermetallic compounds with Al, becoming a corrosion initiation point. In hot and humid environments, the plate is prone to intergranular corrosion (corrosion depth ≥100μm, ASTMG67 standard) and exfoliation corrosion (rated as EB grade, ASTMG34 standard), shortening the service life of the mold; Stress Corrosion Sensitivity: Residual stress and corrosive media synergistically increase the risk of stress corrosion cracking, which is particularly prominent in coastal or chemical environments. 4. Production process limitations: Poor melting and casting uniformity: Conventional melting and casting processes lack effective melt purification and grain refinement methods, resulting in an ingot grain size of only Grade 3 (ASTM E112 standard), obvious microstructure segregation, and difficulty in completely eliminating defects during subsequent processing; Insufficient solution treatment: The existing solution treatment process has large temperature fluctuations (±5°C) and insufficient holding time, resulting in insufficient solute elements (such as Mg2Si) being dissolved in the matrix. This leads to uneven distribution of strengthening phases after aging and significant fluctuations in mechanical properties; Low cooling efficiency: Imprecise water spray flow control during the quenching stage results in a large difference in cooling rates between the plate surface and core, generating thermal stress and exacerbating deformation; Existing technologies are unable to fully meet the above requirements, and an innovative solution that comprehensively optimizes component design, melting and casting process, heat treatment and processing control is urgently needed. Summary of the Invention

[0003] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a production process for SD61 aluminum alloy medium and thick plates.

[0004] To achieve the above object, the present invention provides the following technical solution: a production process for SD61 aluminum alloy medium and thick plates, the specific preparation steps are as follows: S1. Composition design: The raw materials include Si 0.6%-0.8%, Mg 1.0%-1.2%, Fe≤0.3% by mass, and the balance is Al and unavoidable impurity elements; S2. Melting and Casting: The melting temperature is controlled at 720-740°C, and electromagnetic stirring and ultrasonic assisted casting are used. The electromagnetic stirring frequency is 15-20Hz, the magnetic field strength is 0.1-0.15T, the ultrasonic frequency is 20kHz, the power density is 2-3W / cm², and the action time is 10-15min. This achieves high purity, high solute concentration, fine grains, low segregation, and homogeneous casting quality, and obtains an ingot with a grain size of Grade 1 (ASTME112 standard); S3, ingot soaking: the ingot obtained in step S2 is placed in a soaking furnace and kept at 480-520°C for 4-6 hours, and the temperature uniformity in the furnace is controlled within ±5°C; S4. Hot rolling: The soaked ingot is subjected to multiple hot rolling passes, with an initial rolling temperature of 450-470°C, a final rolling temperature of not less than 320°C, and a total reduction of ≥80%, to obtain a billet with a thickness of 45 mm or 115 mm; S5. Solution treatment: The blank is solution treated in a roller hearth quenching furnace. The temperature, water volume and transfer speed are specially controlled to fully dissolve the plate, and ultimately the strength, hardness, conductivity, exfoliation corrosion, stress corrosion and intergranular corrosion performance all meet the requirements of mold use. By controlling the solution temperature, the grain growth is controlled to obtain a finer structure. S6. Stretching: The plate after solutionization is stretched by 2.5%-2.8% to eliminate the residual stress of the plate as much as possible. The flatness of the whole plate after stretching is ≤1.5mm / m to ensure the processing stability of the customer. S7, aging: placing the plate stretched in step S6 in an aging furnace for aging treatment and then air cooling; S8. Finished product sawing: Use CNC sawing machine to cut the aged plates to the required length, with a sawing accuracy of ±0.5mm; S9. Packaging: Cover the surface of the finished board after sawing with anti-oxidation film and fix it with wooden brackets. The longitudinal and transverse binding force should be ≥500N.

[0005] In a preferred embodiment, in step S2, the direction of the magnetic field of the electromagnetic stirring forms an angle of 45°-60° with the melt flow direction, and the ultrasonic transducers are evenly distributed along the axial direction of the ingot with a spacing of 200-300 mm.

[0006] In a preferred embodiment, in step S3, the soaking furnace adopts a step-by-step heating mode, specifically: The first stage: heating to 400℃ at a rate of 50℃ / h and keeping warm for 1 hour; The second stage: heat up to the target temperature of 480-520℃ at a rate of 30℃ / h and keep warm for 4-6 hours.

[0007] In a preferred embodiment, the solution treatment in step S5 controls the temperature in the roller hearth quenching furnace to 545°C, the furnace temperature uniformity to ±3°C, the heating and holding time for 45mm thickness to 80min, and the quenching transfer speed of the plate to 235mm / s; the heating and holding time for 115mm thickness to 180min, and the quenching transfer speed of the plate to 95mm / s, the water spray flow rate on the upper part of the plate to 150-160L / s, and the water spray flow rate on the lower part of the plate to 220-240L / s, and the water temperature of the plate after quenching is controlled below 30°C.

[0008] In a preferred embodiment, in step S6, the stretching process uses a double-chuck synchronous stretching machine, the stretching force error is ≤1%, and the surface stress distribution of the plate is monitored in real time during the stretching process. When the deviation exceeds 5%, the stretching amount is automatically adjusted.

[0009] In a preferred embodiment, aging treatment is performed in step S7, the furnace temperature is controlled between 167°C and 173°C, the temperature uniformity is ±2°C, the wind speed in the furnace is controlled at 0.5-1.0m / s, the plate stacking spacing is ≥50mm, and when the plate temperature reaches the negative tolerance of the furnace temperature uniformity, the plate starts to be kept warm for 12-15 hours, and then the plate is taken out of the furnace and air-cooled.

[0010] In a preferred embodiment, the sawing tool in step S8 is a carbide circular saw blade with a saw tooth rake angle of 10°-15°, a sawing linear speed of 100-120 m / min, and a coolant flow rate of 10-15 L / min.

[0011] In a preferred embodiment, the anti-oxidation film in step S9 is a polyethylene / polypropylene composite film with a thickness of 0.1-0.2 mm and an oxygen permeability of ≤5 cm³ / (m²·24h·0.1 MPa).

[0012] Technical effects and advantages of the present invention: The present invention adjusts the content of key elements based on 6061 aluminum alloy, setting the Si content to enhance fluidity and thermal stability; setting the Mg content to improve strength and corrosion resistance; and reducing Fe content to less than 0.3% to reduce the formation of impurity phases. It is particularly suitable for the production of wide-width plates with thicknesses of 45 mm and 115 mm and widths of more than 2200 mm. This process significantly improves the mechanical properties, dimensional stability, and corrosion resistance of aluminum alloy plates through composition optimization, casting control, heat treatment, and processing technology improvements. DETAILED DESCRIPTION

[0013] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example

[0014] The present invention provides a production process for SD61 aluminum alloy medium and thick plates, and the specific preparation steps are as follows: S1. Composition design: The raw materials include Si 0.6%-0.8%, Mg 1.0%-1.2%, Fe≤0.3% by mass, and the balance is Al and unavoidable impurity elements; S2. Melting and Casting: The melting temperature is controlled at 720-740°C, and electromagnetic stirring and ultrasonic assisted casting are used. The electromagnetic stirring frequency is 15-20Hz, the magnetic field intensity is 0.1-0.15T, the ultrasonic frequency is 20kHz, the power density is 2-3W / cm², and the action time is 10-15min. The magnetic field direction of the electromagnetic stirring is at an angle of 45°-60° to the melt flow direction. The ultrasonic transducers are evenly distributed along the axial direction of the ingot, with a spacing of 200-300mm. This achieves high purity, high solute concentration, fine grains, low segregation, and homogeneous casting quality, and obtains an ingot with a grain size of Grade 1 (ASTM E112 standard); S3. Ingot soaking: The ingot obtained in step S2 is placed in a soaking furnace and kept at 480-520°C for 4-6 hours. The temperature uniformity in the furnace is controlled within ±5°C. The soaking furnace adopts a step-by-step heating mode, specifically: The first stage: heating to 400℃ at a rate of 50℃ / h and keeping warm for 1 hour; The second stage: heating to the target temperature of 480-520℃ at a rate of 30℃ / h and keeping warm for 4-6 hours; S4. Hot rolling: The soaked ingot is subjected to multiple hot rolling passes, with an initial rolling temperature of 450-470°C, a final rolling temperature of not less than 320°C, and a total reduction of ≥80%, to obtain a billet with a thickness of 45 mm or 115 mm; S5. Solution treatment: The blank is solution treated in a roller hearth quenching furnace. The temperature, water volume and transfer speed are specially controlled to fully dissolve the plate, and ultimately the strength, hardness, conductivity, exfoliation corrosion, stress corrosion and intergranular corrosion properties all meet the requirements of mold use. By controlling the solution temperature, the grain growth is controlled to obtain a finer structure. During the solution treatment, the temperature in the roller hearth quenching furnace is controlled at 545°C, the furnace temperature uniformity is controlled at ±3°C, the heating and holding time for 45mm thickness is controlled at 80min, and the quenching transfer speed of the plate is 235mm / s; the heating and holding time for 115mm thickness is controlled at 180min, and the quenching transfer speed of the plate is 95mm / s. The water spray flow rate on the upper part of the plate is 150-160L / s, and the water spray flow rate on the lower part of the plate is 220-240L / s. The water temperature of the plate after quenching is controlled below 30°C. S6. Stretching: The plate after solutionization is stretched with a stretching amount of 2.5%-2.8% to eliminate the residual stress of the plate as much as possible. The flatness of the whole plate after stretching is ≤1.5mm / m to ensure the processing stability of the customer. The stretching process uses a double-chuck synchronous stretching machine with a stretching force error of ≤1%. The stress distribution on the plate surface is monitored in real time during the stretching process. If the deviation exceeds 5%, the stretching amount is automatically adjusted. S7, aging: Place the plate stretched in step S6 in an aging furnace for aging treatment and then air-cool; control the furnace temperature between 167°C and 173°C, the temperature uniformity is ±2°C, the wind speed in the furnace is controlled at 0.5-1.0m / s, and the plate stacking spacing is ≥50mm. When the plate temperature reaches the negative tolerance of the furnace temperature uniformity, start the insulation, keep it warm for 12-15 hours, and then take it out of the furnace and air-cool; Aging treatment is mainly used to further eliminate residual stress inside the plate and ensure the stability of the machining process. At the same time, a strengthening phase is formed during the aging process to improve the plate's comprehensive mechanical and corrosion properties. The mechanical properties of ordinary 6061T651 plates are generally tensile strength of 290-310MPa, yield strength of about 250-270MPa, and elongation of about 9%. The overall mechanical properties of SD61 plates are much higher than those of 6061T651, with tensile strength of 310-330MPa, yield strength of 270-290MPa, and elongation of about 13%. The overall strength and plasticity are higher than those of ordinary 6061T651. The Brinell hardness of ordinary 6061T651 is generally 90-100HBW, while the Brinell hardness of SD61 plates is 105-110HBW. The comprehensive performance of SD61 aluminum alloy plates for molds is far superior to that of 6061T651 plates. S8. Finished product sawing: Use CNC sawing machine to cut the aged plates to the required length, with a sawing accuracy of ±0.5mm; the sawing tool is a carbide circular saw blade with a saw tooth rake angle of 10°-15°, a sawing speed of 100-120m / min, and a coolant flow rate of 10-15L / min; S9. Packaging: Cover the surface of the sawn finished board with anti-oxidation film and fix it with wooden brackets. The longitudinal and transverse strapping force should be ≥500N. The anti-oxidation film should be polyethylene / polypropylene composite film with a thickness of 0.1-0.2mm and an oxygen permeability of ≤5cm³ / (m²·24h·0.1MPa). Specifically in this embodiment, the raw material components include Si 0.6%, Mg 1.2%, Fe≤0.3% by mass, and the balance is Al and unavoidable impurity elements. Example

[0015] The present invention provides a production process for SD61 aluminum alloy medium and thick plates, and the specific preparation steps are as follows: S1. Composition design: The raw materials include Si 0.6%-0.8%, Mg 1.0%-1.2%, Fe≤0.3% by mass, and the balance is Al and unavoidable impurity elements; S2. Melting and Casting: The melting temperature is controlled at 720-740°C, and electromagnetic stirring and ultrasonic assisted casting are used. The electromagnetic stirring frequency is 15-20Hz, the magnetic field intensity is 0.1-0.15T, the ultrasonic frequency is 20kHz, the power density is 2-3W / cm², and the action time is 10-15min. The magnetic field direction of the electromagnetic stirring is at an angle of 45°-60° to the melt flow direction. The ultrasonic transducers are evenly distributed along the axial direction of the ingot, with a spacing of 200-300mm. This achieves high purity, high solute concentration, fine grains, low segregation, and homogeneous casting quality, and obtains an ingot with a grain size of Grade 1 (ASTM E112 standard); S3. Ingot soaking: The ingot obtained in step S2 is placed in a soaking furnace and kept at 480-520°C for 4-6 hours. The temperature uniformity in the furnace is controlled within ±5°C. The soaking furnace adopts a step-by-step heating mode, specifically: The first stage: heating to 400℃ at a rate of 50℃ / h and keeping warm for 1 hour; The second stage: heating to the target temperature of 480-520℃ at a rate of 30℃ / h and keeping warm for 4-6 hours; S4. Hot rolling: The soaked ingot is subjected to multiple hot rolling passes, with an initial rolling temperature of 450-470°C, a final rolling temperature of not less than 320°C, and a total reduction of ≥80%, to obtain a billet with a thickness of 45 mm or 115 mm; S5. Solution treatment: The blank is solution treated in a roller hearth quenching furnace. The temperature, water volume and transfer speed are specially controlled to fully dissolve the plate, and ultimately the strength, hardness, conductivity, exfoliation corrosion, stress corrosion and intergranular corrosion properties all meet the requirements of mold use. By controlling the solution temperature, the grain growth is controlled to obtain a finer structure. During the solution treatment, the temperature in the roller hearth quenching furnace is controlled at 545°C, the furnace temperature uniformity is controlled at ±3°C, the heating and holding time for 45mm thickness is controlled at 80min, and the quenching transfer speed of the plate is 235mm / s; the heating and holding time for 115mm thickness is controlled at 180min, and the quenching transfer speed of the plate is 95mm / s. The water spray flow rate on the upper part of the plate is 150-160L / s, and the water spray flow rate on the lower part of the plate is 220-240L / s. The water temperature of the plate after quenching is controlled below 30°C. S6. Stretching: The plate after solutionization is stretched with a stretching amount of 2.5%-2.8% to eliminate the residual stress of the plate as much as possible. The flatness of the whole plate after stretching is ≤1.5mm / m to ensure the processing stability of the customer. The stretching process uses a double-chuck synchronous stretching machine with a stretching force error of ≤1%. The stress distribution on the plate surface is monitored in real time during the stretching process. If the deviation exceeds 5%, the stretching amount is automatically adjusted. S7, aging: Place the plate stretched in step S6 in an aging furnace for aging treatment and then air-cool; control the furnace temperature between 167°C and 173°C, the temperature uniformity is ±2°C, the wind speed in the furnace is controlled at 0.5-1.0m / s, and the plate stacking spacing is ≥50mm. When the plate temperature reaches the negative tolerance of the furnace temperature uniformity, start the insulation, keep it warm for 12-15 hours, and then take it out of the furnace and air-cool; Aging treatment is mainly used to further eliminate residual stress inside the plate and ensure the stability of the machining process. At the same time, a strengthening phase is formed during the aging process to improve the plate's comprehensive mechanical and corrosion properties. The mechanical properties of ordinary 6061T651 plates are generally tensile strength of 290-310MPa, yield strength of about 250-270MPa, and elongation of about 9%. The overall mechanical properties of SD61 plates are much higher than those of 6061T651, with tensile strength of 310-330MPa, yield strength of 270-290MPa, and elongation of about 13%. The overall strength and plasticity are higher than those of ordinary 6061T651. The Brinell hardness of ordinary 6061T651 is generally 90-100HBW, while the Brinell hardness of SD61 plates is 105-110HBW. The comprehensive performance of SD61 aluminum alloy plates for molds is far superior to that of 6061T651 plates. S8. Finished product sawing: Use CNC sawing machine to cut the aged plates to the required length, with a sawing accuracy of ±0.5mm; the sawing tool is a carbide circular saw blade with a saw tooth rake angle of 10°-15°, a sawing speed of 100-120m / min, and a coolant flow rate of 10-15L / min; S9. Packaging: Cover the surface of the sawn finished board with anti-oxidation film and fix it with wooden brackets. The longitudinal and transverse strapping force should be ≥500N. The anti-oxidation film should be polyethylene / polypropylene composite film with a thickness of 0.1-0.2mm and an oxygen permeability of ≤5cm³ / (m²·24h·0.1MPa). Specifically in this embodiment, the raw material components include Si 0.7%, Mg 1.1%, Fe≤0.3%, and the balance is Al and unavoidable impurity elements. Example

[0016] The present invention provides a production process for SD61 aluminum alloy medium and thick plates, and the specific preparation steps are as follows: S1. Composition design: The raw materials include Si 0.6%-0.8%, Mg 1.0%-1.2%, Fe≤0.3% by mass, and the balance is Al and unavoidable impurity elements; S2. Melting and Casting: The melting temperature is controlled at 720-740°C, and electromagnetic stirring and ultrasonic assisted casting are used. The electromagnetic stirring frequency is 15-20Hz, the magnetic field intensity is 0.1-0.15T, the ultrasonic frequency is 20kHz, the power density is 2-3W / cm², and the action time is 10-15min. The magnetic field direction of the electromagnetic stirring is at an angle of 45°-60° to the melt flow direction. The ultrasonic transducers are evenly distributed along the axial direction of the ingot, with a spacing of 200-300mm. This achieves high purity, high solute concentration, fine grains, low segregation, and homogeneous casting quality, and obtains an ingot with a grain size of Grade 1 (ASTM E112 standard); S3. Ingot soaking: The ingot obtained in step S2 is placed in a soaking furnace and kept at 480-520°C for 4-6 hours. The temperature uniformity in the furnace is controlled within ±5°C. The soaking furnace adopts a step-by-step heating mode, specifically: The first stage: heating to 400℃ at a rate of 50℃ / h and keeping warm for 1 hour; The second stage: heating to the target temperature of 480-520℃ at a rate of 30℃ / h and keeping warm for 4-6 hours; S4. Hot rolling: The soaked ingot is subjected to multiple hot rolling passes, with an initial rolling temperature of 450-470°C, a final rolling temperature of not less than 320°C, and a total reduction of ≥80%, to obtain a billet with a thickness of 45 mm or 115 mm; S5. Solution treatment: The blank is solution treated in a roller hearth quenching furnace. The temperature, water volume and transfer speed are specially controlled to fully dissolve the plate, and ultimately the strength, hardness, conductivity, exfoliation corrosion, stress corrosion and intergranular corrosion properties all meet the requirements of mold use. By controlling the solution temperature, the grain growth is controlled to obtain a finer structure. During the solution treatment, the temperature in the roller hearth quenching furnace is controlled at 545°C, the furnace temperature uniformity is controlled at ±3°C, the heating and holding time for 45mm thickness is controlled at 80min, and the quenching transfer speed of the plate is 235mm / s; the heating and holding time for 115mm thickness is controlled at 180min, and the quenching transfer speed of the plate is 95mm / s. The water spray flow rate on the upper part of the plate is 150-160L / s, and the water spray flow rate on the lower part of the plate is 220-240L / s. The water temperature of the plate after quenching is controlled below 30°C. S6. Stretching: The plate after solutionization is stretched with a stretching amount of 2.5%-2.8% to eliminate the residual stress of the plate as much as possible. The flatness of the whole plate after stretching is ≤1.5mm / m to ensure the processing stability of the customer. The stretching process uses a double-chuck synchronous stretching machine with a stretching force error of ≤1%. The stress distribution on the plate surface is monitored in real time during the stretching process. If the deviation exceeds 5%, the stretching amount is automatically adjusted. S7, aging: Place the plate stretched in step S6 in an aging furnace for aging treatment and then air-cool; control the furnace temperature between 167°C and 173°C, the temperature uniformity is ±2°C, the wind speed in the furnace is controlled at 0.5-1.0m / s, and the plate stacking spacing is ≥50mm. When the plate temperature reaches the negative tolerance of the furnace temperature uniformity, start the insulation, keep it warm for 12-15 hours, and then take it out of the furnace and air-cool; Aging treatment is mainly used to further eliminate residual stress inside the plate and ensure the stability of the machining process. At the same time, a strengthening phase is formed during the aging process to improve the plate's comprehensive mechanical and corrosion properties. The mechanical properties of ordinary 6061T651 plates are generally tensile strength of 290-310MPa, yield strength of about 250-270MPa, and elongation of about 9%. The overall mechanical properties of SD61 plates are much higher than those of 6061T651, with tensile strength of 310-330MPa, yield strength of 270-290MPa, and elongation of about 13%. The overall strength and plasticity are higher than those of ordinary 6061T651. The Brinell hardness of ordinary 6061T651 is generally 90-100HBW, while the Brinell hardness of SD61 plates is 105-110HBW. The comprehensive performance of SD61 aluminum alloy plates for molds is far superior to that of 6061T651 plates. S8. Finished product sawing: Use CNC sawing machine to cut the aged plates to the required length, with a sawing accuracy of ±0.5mm; the sawing tool is a carbide circular saw blade with a saw tooth rake angle of 10°-15°, a sawing speed of 100-120m / min, and a coolant flow rate of 10-15L / min; S9. Packaging: Cover the surface of the sawn finished board with anti-oxidation film and fix it with wooden brackets. The longitudinal and transverse strapping force should be ≥500N. The anti-oxidation film should be polyethylene / polypropylene composite film with a thickness of 0.1-0.2mm and an oxygen permeability of ≤5cm³ / (m²·24h·0.1MPa). Specifically in this embodiment, the raw material components include Si 0.8%, Mg 1.0%, Fe≤0.3%, and the balance is Al and unavoidable impurity elements. Example

[0017] The performance data of the SD61 aluminum alloy medium and thick plates prepared in Examples 1-3 above were compared with the conventional 6061-T651 aluminum alloy in the prior art, and the following data were obtained: Performance indicators SD61 aluminum alloy Ordinary 6061-T651 Improvement Tensile strength (MPa) 310-330 290-310 +8% Yield strength (MPa) 270-290 250-270 +7% Elongation (%) 13 9 +44% As can be seen from the table above, the improved aluminum alloy has different degrees of improvement in tensile strength, yield strength and elongation compared to the ordinary 6061-T651 aluminum alloy in existing technologies. Combined with electromagnetic stirring and ultrasonic-assisted melting and casting, precise solution quenching, high-precision stretching and low-temperature aging processes, the mechanical properties and corrosion resistance of the plate are significantly improved; it can meet the high-quality production needs of wide (2200mm) and thick plates (45mm / 115mm).

[0018] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A production process for SD61 aluminum alloy medium and thick plates, characterized by: The specific preparation steps are as follows: S1. Composition design: The raw materials include Si 0.6%-0.8%, Mg 1.0%-1.2%, Fe≤0.3% by mass, and the balance is Al and unavoidable impurity elements; S2. Melting and casting: The melting temperature is controlled at 720-740°C, and electromagnetic stirring and ultrasonic assisted casting are used. The electromagnetic stirring frequency is 15-20 Hz, the magnetic field strength is 0.1-0.15 T, the ultrasonic frequency is 20 kHz, the power density is 2-3 W / cm², and the action time is 10-15 minutes to obtain an ingot with a grain size of level 1; S3, ingot soaking: the ingot obtained in step S2 is placed in a soaking furnace and kept at 480-520°C for 4-6 hours, and the temperature uniformity in the furnace is controlled within ±5°C; S4. Hot rolling: The soaked ingot is subjected to multiple hot rolling passes, with an initial rolling temperature of 450-470°C, a final rolling temperature of not less than 320°C, and a total reduction of ≥80%, to obtain a billet with a thickness of 45 mm or 115 mm; S5. Solution treatment: The blank is solution treated in a roller hearth quenching furnace. The temperature, water volume and transfer speed are specially controlled to fully dissolve the plate, and ultimately the strength, hardness, conductivity, exfoliation corrosion, stress corrosion and intergranular corrosion performance all meet the requirements of mold use. By controlling the solution temperature, the grain growth is controlled to obtain a finer structure. S6. Stretching: The plate after solutionization is stretched with a stretching amount of 2.5%-2.8%. The flatness of the whole plate after stretching is ≤1.5mm / m; S7, aging: placing the plate stretched in step S6 in an aging furnace for aging treatment and then air cooling; S8. Finished product sawing: Use CNC sawing machine to cut the aged plates to the required length, with a sawing accuracy of ±0.5mm; S9. Packaging: Cover the surface of the finished board after sawing with anti-oxidation film and fix it with wooden brackets. The longitudinal and transverse binding force should be ≥500N.

2. The process for producing SD61 aluminum alloy medium and thick plates according to claim 1, wherein: In step S2, the direction of the magnetic field of the electromagnetic stirring forms an angle of 45°-60° with the melt flow direction, and the ultrasonic transducers are evenly distributed along the axial direction of the ingot with a spacing of 200-300 mm.

3. The process for producing SD61 aluminum alloy medium and thick plates according to claim 1, wherein: In step S3, the soaking furnace adopts a step-by-step heating mode, specifically: The first stage: heating to 400℃ at a rate of 50℃ / h and keeping warm for 1 hour; The second stage: heat up to the target temperature of 480-520℃ at a rate of 30℃ / h and keep warm for 4-6 hours.

4. The process for producing SD61 aluminum alloy medium and thick plates according to claim 1, wherein: In the solution treatment in step S5, the temperature in the roller hearth quenching furnace is controlled at 545°C, the furnace temperature uniformity is controlled at ±3°C, the heating and holding time for the plate with a thickness of 45 mm is controlled at 80 min, and the quenching transfer speed of the plate is 235 mm / s; the heating and holding time for the plate with a thickness of 115 mm is controlled at 180 min, and the quenching transfer speed of the plate is 95 mm / s, the water spray flow rate on the upper part of the plate is 150-160 L / s, and the water spray flow rate on the lower part of the plate is 220-240 L / s, and the water temperature of the plate after quenching is controlled below 30°C.

5. The process for producing SD61 aluminum alloy medium and thick plates according to claim 1, wherein: In step S6, the stretching process uses a double-chuck synchronous stretching machine, the stretching force error is ≤1%, and the stress distribution on the plate surface is monitored in real time during the stretching process. When the deviation exceeds 5%, the stretching amount is automatically adjusted.

6. The process for producing SD61 aluminum alloy medium and thick plates according to claim 1, characterized in that: In step S7, aging treatment is performed, the furnace temperature is controlled between 167°C and 173°C, the temperature uniformity is ±2°C, the wind speed in the furnace is controlled at 0.5-1.0m / s, and the plate stacking spacing is ≥50mm. When the plate temperature reaches the negative tolerance of the furnace temperature uniformity, the plate starts to be kept warm for 12-15 hours, and then taken out of the furnace for air cooling.

7. The process for producing SD61 aluminum alloy medium and thick plates according to claim 1, characterized in that: In step S8, the sawing tool is a carbide circular saw blade with a saw tooth rake angle of 10°-15°, a sawing linear speed of 100-120 m / min, and a coolant flow rate of 10-15 L / min.

8. The process for producing SD61 aluminum alloy medium and thick plates according to claim 1, characterized in that: The anti-oxidation film in step S9 is a polyethylene / polypropylene composite film with a thickness of 0.1-0.2 mm and an oxygen permeability of ≤5 cm³ / (m²·24h·0.1 MPa).