Preparation method for eliminating black filament defect on surface of 5-series aluminum alloy plate strip

Abstract

The invention discloses a preparation method for eliminating black filament defects on the surface of a 5-series aluminum alloy plate strip, and relates to the technical field of aluminum alloy processing, in particular to the preparation method for eliminating the black filament defects on the surface of the 5-series aluminum alloy plate strip. The invention aims to solve the problem of black filament defect in the existing 5-series aluminum alloy plate strip rolling process. The method comprises the following steps: 1, weighing: weighing smelting raw materials in proportion; the weighed smelting raw materials are partially smelted, and aluminum alloy melt is obtained; 2, casting; 3, heating with uniform fire, and cooling to room temperature along with the furnace; 4, sawing head and tail casting head areas and cold shut areas, and milling large surface and end surface surface oxide skin; 5, placing the flat cast ingot in a heating furnace, keeping the constant temperature at 470 DEG C, and keeping the temperature until the flat cast ingot is discharged from the furnace for hot rough rolling; sixthly, hot finish rolling is conducted, and a hot-rolled coiled material blank is obtained; and seventhly, the hot-rolled coiled material blank is subjected to thinning rolling through a cold-rolling mill, and the 5-series aluminum alloy coiled material blank without the black wire defect on the surface is obtained. The method is used for eliminating the black filament defect on the surface of the 5-series aluminum alloy plate strip.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy processing, and in particular to a preparation method for eliminating black wire defects on the surface of a 5 series aluminum alloy plate and strip. Background Art

[0002] Aluminum alloy materials are widely used in the market in the fields of aviation, transportation, 3C electronics, new energy, sports and construction.

[0003] Breakthroughs in aluminum alloy surface treatment technology have prompted the civilian market to have more stringent requirements on aluminum alloy materials and aluminum alloy surfaces, and competition has become increasingly fierce. Anodized aluminum alloys can not only improve the corrosion resistance, wear resistance, and insulation of aluminum bases, but can also be used as decorative base materials and surface painted aluminum after surface coloring. Aluminum can also form a stable aluminum oxide corrosion-resistant film under natural conditions, but the uniformity of the oxide film is poor, resulting in poor light sensitivity and poor visual effects on the aluminum alloy surface. At the same time, the oxide film under natural conditions is thin and has low strength, and it is easy to be scratched, resulting in surface defects and unstable performance. Anodizing can obtain a uniform, dense, and higher-strength oxide film, which not only greatly improves the surface optical effect, but also greatly improves the strength and corrosion resistance. After surface oxidation treatment, aluminum-based products are coated with special dyes on the surface, which can be used as a new generation of decorative materials comparable to traditional ceramics and wooden furniture. Because of its light weight, corrosion resistance, high strength, wear resistance, and wide surface color range, it will become a new generation of "green, environmentally friendly, and low-carbon" decoration materials. The new energy vehicle industry is gradually becoming the representative of the automotive industry. Consumers have higher aesthetic requirements for the appearance quality of new energy vehicles, and therefore have higher requirements for the surface quality of aluminum substrates. The surface of aluminum-based sheets is almost defect-free.

[0004] At present, the domestic high surface alloy preparation process is that after aluminum alloy casting and rolling thinning, black wire defects are easily formed on the surface, which seriously affects the surface quality of the plate and strip and subsequent processing. The subsequent oxidation processing can only obtain high surface quality aluminum by cutting the aluminum base surface size, which not only restricts the product formability, but also reduces production efficiency and increases manufacturing costs. Summary of the invention

[0005] The present invention aims to solve the problem of black wire defects generated during the rolling process of the existing 5 series aluminum alloy plate and strip, and to provide a preparation method for eliminating the black wire defects on the surface of the 5 series aluminum alloy plate and strip.

[0006] A preparation method for eliminating black wire defects on the surface of 5 series aluminum alloy plate and strip is completed by the following steps:

[0007] 1. Weighing: According to the proportion of Mg being 4.80% to 5.40%, Mn being 0.25% to 0.45%, Si≤0.35%, Fe≤0.35%, Cu≤0.35%, Fe+Si≤0.60%, Ti≤0.10%, Be being 0.0005% to 0.005% and the balance being Al, weigh remelted aluminum ingots, aluminum-manganese alloy ingots, aluminum-titanium alloy ingots, aluminum-beryllium alloy ingots and magnesium ingots as smelting raw materials; add the weighed smelting raw materials into a natural gas melting furnace according to the proportion of remelted aluminum ingots, aluminum-manganese alloy ingots, magnesium ingots and aluminum-beryllium alloy ingots for smelting to obtain aluminum alloy melt;

[0008] 2. Casting the aluminum alloy melt to obtain a 5 series aluminum alloy ingot;

[0009] 3. The 5 series aluminum alloy ingot is heated to 460°C to 490°C, kept at this temperature for 20h to 40h, and cooled to room temperature with the furnace to obtain a 5 series aluminum alloy ingot;

[0010] Fourth, the 5 series aluminum alloy ingot is sawed to cut the head and tail pouring riser area and the cold shut area, and the oxide scale on the large surface and the end surface is milled, and the milling amount is 10-20mm to obtain a flat ingot;

[0011] 5. Place the flat ingot in a heating furnace, keep it at 550°C to 560°C for 9 hours, turn it to a constant temperature of 470°C and keep it until it is taken out of the furnace for hot rough rolling, and then reduce the thickness to 23 to 25 mm by hot rough rolling to obtain an intermediate billet aluminum alloy;

[0012] 6. Thinning the intermediate billet aluminum alloy to 4.0 mm to 5.5 mm by hot finish rolling to obtain a hot rolled coil billet;

[0013] 7. The hot-rolled coil blank is thinned and rolled in a cold rolling mill to obtain a 5 series aluminum alloy coil blank with no black wire defects on the surface.

[0014] Beneficial effects of the present invention:

[0015] The present invention adopts a controlled casting process, adjusts the proportion of alloying elements in the aluminum alloy, optimizes the chemical composition, controls the rolling process, adjusts the roller brush material, roller brush pressure, roller brush torque and roller brush speed, controls the lubrication process, adjusts the working temperature of the lubricating medium, spray pressure, spray flow, spray angle, and working roller spray surface area, so as to comprehensively improve the surface quality of hot-rolled billets of plates and strips, eliminate surface black wire defects, solve the problem of reduced plate and strip yield due to black wire defects, and break through the key surface quality control and preparation process core technology of 5 series aluminum alloys.

[0016] The present invention solves the problem that aluminum-based materials cannot be used for appearance parts due to surface black wire defects. It not only improves the surface quality of products and reduces users' production and manufacturing costs, but also opens up new markets for users, broadens the application fields, and provides technical support for the high-surface civilian aluminum alloy market. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0018] Specific implementation method 1: In this implementation method, a preparation method for eliminating black wire defects on the surface of a 5-series aluminum alloy plate and strip is completed by the following steps:

[0019] 1. Weighing: According to the proportion of Mg being 4.80% to 5.40%, Mn being 0.25% to 0.45%, Si≤0.35%, Fe≤0.35%, Cu≤0.35%, Fe+Si≤0.60%, Ti≤0.10%, Be being 0.0005% to 0.005% and the balance being Al, weigh remelted aluminum ingots, aluminum-manganese alloy ingots, aluminum-titanium alloy ingots, aluminum-beryllium alloy ingots and magnesium ingots as smelting raw materials; add the weighed smelting raw materials into a natural gas melting furnace according to the proportion of remelted aluminum ingots, aluminum-manganese alloy ingots, magnesium ingots and aluminum-beryllium alloy ingots for smelting to obtain aluminum alloy melt;

[0020] 2. Casting the aluminum alloy melt to obtain a 5 series aluminum alloy ingot;

[0021] 3. The 5 series aluminum alloy ingot is heated to 460°C to 490°C, kept at this temperature for 20h to 40h, and cooled to room temperature with the furnace to obtain a 5 series aluminum alloy ingot;

[0022] Fourth, the 5 series aluminum alloy ingot is sawed to cut the head and tail pouring riser area and the cold shut area, and the oxide scale on the large surface and the end surface is milled, and the milling amount is 10-20mm to obtain a flat ingot;

[0023] 5. Place the flat ingot in a heating furnace, keep it at 550°C to 560°C for 9 hours, turn it to a constant temperature of 470°C and keep it until it is taken out of the furnace for hot rough rolling, and then reduce the thickness to 23 to 25 mm by hot rough rolling to obtain an intermediate billet aluminum alloy;

[0024] 6. Thinning the intermediate billet aluminum alloy to 4.0 mm to 5.5 mm by hot finish rolling to obtain a hot rolled coil billet;

[0025] 7. The hot-rolled coil blank is thinned and rolled in a cold rolling mill to obtain a 5 series aluminum alloy coil blank with no black wire defects on the surface.

[0026] The Si element content in the aluminum alloy flat ingot of this embodiment is ≤0.35%, and the Fe element content is ≤0.35%, which are derived from impurities in the aluminum ingot smelting process. The content of other single impurity elements is ≤0.05%. The impurity element content within this range has no effect on the forming performance and rolling surface of the aluminum alloy flat ingot.

[0027] This implementation method eliminates black wire defects on the surface of aluminum alloy plates and strips by regulating the casting process, rolling process and lubrication process, and also provides a process technology foundation and practical direction for the subsequent improvement of other surface defects of aluminum alloys.

[0028] This embodiment ensures that the chemical composition of the aluminum alloy is within a reasonable and stable range by strictly weighing each element as a smelting raw material according to a specific mass percentage. The appropriate element ratio helps to form a uniform microstructure and reduce the possibility of black wire defects in the subsequent rolling process due to problems such as component segregation. The specific order of addition may be conducive to better fusion of the raw materials during the smelting process, promote uniform distribution of elements, avoid local component abnormalities, and thus provide a uniform aluminum alloy melt foundation for subsequent casting and rolling processes, reducing the risk of black wire defects.

[0029] This embodiment casts the molten aluminum alloy after smelting. If the casting process is properly controlled, the molten aluminum alloy can form a relatively uniform organizational structure during the solidification process, reducing the occurrence of internal defects. The uniform ingot structure can deform more evenly during subsequent rolling, reducing the probability of black wire defects caused by problems such as local stress concentration. The annealing treatment can eliminate the internal stress generated during the casting process and make the internal structure of the ingot more uniform and stable. In the subsequent rolling process, the deformation capacity of each part of the ingot that has been annealed is more consistent, which can effectively avoid the occurrence of local abnormal deformation and black wire defects during rolling due to uneven organization.

[0030] In the process of processing the 5 series aluminum alloy ingot into a flat ingot, this embodiment can remove the poor quality areas and oxide layers that may exist on the surface and end of the ingot by sawing the head and tail pouring riser area and the cold shut area, and milling the oxide scale on the large surface and the end surface. If these poor areas and oxide scales are not removed, they may cause black wire defects in the subsequent rolling process due to uneven contact with equipment such as rollers or irregular deformation of themselves, and removing them provides better billet conditions for subsequent rolling.

[0031] In this embodiment, suitable heating temperature, holding time and thinning rolling parameters are set for the flat ingot and intermediate billet aluminum alloy in the hot rough rolling and hot finish rolling stages. Reasonable temperature control can keep the aluminum alloy in good plasticity and deformation capacity during the rolling process, so that it can deform evenly, reduce problems such as local hardening or uneven deformation caused by improper temperature, and thus avoid the generation of black wire defects.

[0032] The cold rolling mill thinning rolling process is also based on the good billets provided by the previous processes, and further thins the hot rolled coil billets to finally obtain 5 series aluminum alloy coil billets without black wire defects on the surface. The gradual and reasonable thinning control during the entire rolling process ensures the stability and uniformity of the aluminum alloy during the deformation process, and reduces the possibility of black wire defects caused by unreasonable rolling process parameters.

[0033] Specific embodiment 2: This embodiment is different from specific embodiment 1 in that the smelting in step 1 is carried out at a temperature of 700° C. to 740° C. for 2 h to 4 h. The rest is the same as specific embodiment 1.

[0034] Specific implementation method 3: This implementation method is different from specific implementation method 1 in that: in the smelting process in step 1, two 20-min inert gas dehydrogenation refining processes are performed at intervals of more than 1 hour. The rest is the same as specific implementation method 1.

[0035] Specific embodiment 4: This embodiment is different from the specific embodiment 1 in that the size of the 5 series aluminum alloy ingot in step 2 is 660 mm×1610 mm×70000 mm. The rest is the same as the specific embodiment 1.

[0036] Specific embodiment 5: This embodiment differs from specific embodiment 1 in that the casting process parameters in step 2 are: temperature of 700°C to 730°C, casting speed of 80mm / min to 85mm / min, cooling water pressure of 0.05Mpa to 0.1Mpa, and water temperature of 10°C to 30°C. Others are the same as specific embodiment 1.

[0037] Specific implementation example 6: This implementation example is different from the specific implementation example 1 in that the size of the flat ingot in step 4 is 640 mm×1610 mm×6700 mm. The rest is the same as the specific implementation example 1.

[0038] Specific embodiment 7: This embodiment is different from the specific embodiment 1 in that the process parameters of the hot rough rolling described in step 5 are: rolling temperature is 445℃~455℃, working roll crown is set to 0.03mm, lubricating medium concentration is 3.5%~3.9%, UA is 3.2%~3.6%, TE is 20%~23%, E1 is 4.4%~5.4%, OS is 8.2%~8.6%, lubricating medium temperature is 55℃~60℃, roller brush pressure is 5KN, roller brush torque is 70NM, roller brush speed is 3m / min, roller table lubrication is turned on, the fan above the roller table is started, and the intermediate billet temperature is controlled at 360℃~380℃. Others are the same as the specific embodiment 1.

[0039] Specific embodiment eight: This embodiment differs from specific embodiment one in that the process parameters of hot finishing rolling described in step six are as follows: the finishing mill inlet temperature is 360°C to 380°C, the lubricating medium concentration is 7.0% to 7.5%, UA is 8.4% to 8.7%, TE is 30% to 32%, E1 is 2.3% to 2.3%, OS is 10.0% to 10.2%, ESI is 0.9% to 0.93%, the lubricating medium temperature is 55°C to 60°C, the finishing mill working roll crown is -0.005mm, the roller brush is made of steel brush material, and the pressing force is set to 6 .0KN, brush marks of steel brush are 20mm~40mm, average torque of upper roller brush is 40Nm~45Nm, average torque of lower roller brush is 45Nm~50Nm, roller brush rotation speed is 3m / s; average processing rate of three passes is 40%, speed of first pass is 2m / min, speed of second pass is 2m / min, speed of third pass is 1.5m / min; angle of nozzle of lubricating spray beam is adjusted to 45° counterclockwise, spray area of ​​eight nozzles of upper and lower spray beams at inlet and outlet is uniform 30mm*10mm, nozzle is clean and free of debris, and spray pressure of each nozzle is the same. Others are the same as the first embodiment.

[0040] Specific embodiment 9: This embodiment is different from specific embodiment 8 in that the final temperature of the hot finishing rolling process is controlled at 280° C. to 320° C. The rest is the same as specific embodiment 8.

[0041] Specific embodiment 10: This embodiment differs from the specific embodiment 1 in that the process parameters of the thinning rolling described in step 7 are as follows: the cold rolling temperature is 40℃~50℃ for the first pass, 70℃~80℃ for the second pass, and 100℃~120℃ for the third pass; the rolling oil viscosity is 2.50%~2.7%, the alcohol content is 2.20%~2.6%, the fat content is 9.37%~9.64%, and the average pass processing rate is 30%. Others are the same as the specific embodiment 1.

[0042] The following examples are used to verify the beneficial effects of the present invention:

[0043] Embodiment 1: A preparation method for eliminating black wire defects on the surface of 5 series aluminum alloy plate and strip is completed by the following steps:

[0044] 1. Weighing: According to the proportion of Mg being 4.80% to 5.40%, Mn being 0.25% to 0.45%, Si≤0.35%, Fe≤0.35%, Cu≤0.35%, Fe+Si≤0.60%, Ti≤0.10%, Be being 0.0005% to 0.005% and the balance being Al, weigh remelted aluminum ingots, aluminum-manganese alloy ingots, aluminum-titanium alloy ingots, aluminum-beryllium alloy ingots and magnesium ingots as smelting raw materials; add the weighed smelting raw materials into a natural gas melting furnace according to the proportion of remelted aluminum ingots, aluminum-manganese alloy ingots, magnesium ingots and aluminum-beryllium alloy ingots for smelting to obtain aluminum alloy melt;

[0045] 2. Casting the aluminum alloy melt to obtain a 5 series aluminum alloy ingot;

[0046] 3. The 5 series aluminum alloy ingot is heated to 460°C to 490°C, kept at this temperature for 20h to 40h, and cooled to room temperature with the furnace to obtain a 5 series aluminum alloy ingot;

[0047] Fourth, the 5 series aluminum alloy ingot is sawed to cut the head and tail pouring riser area and the cold shut area, and the oxide scale on the large surface and the end surface is milled, and the milling amount is 10-20mm to obtain a flat ingot;

[0048] 5. Place the flat ingot in a heating furnace, keep it at 550°C to 560°C for 9 hours, turn it to a constant temperature of 470°C and keep it until it is taken out of the furnace for hot rough rolling, and then reduce the thickness to 23 to 25 mm by hot rough rolling to obtain an intermediate billet aluminum alloy;

[0049] 6. Thinning the intermediate billet aluminum alloy to 4.0 mm to 5.5 mm by hot finish rolling to obtain a hot rolled coil billet;

[0050] 7. The hot-rolled coil blank is thinned and rolled in a cold rolling mill to obtain a 5 series aluminum alloy coil blank with no black wire defects on the surface.

[0051] The smelting in step 1 is carried out at a temperature of 700° C. to 740° C. for 2 h to 4 h.

[0052] During the smelting process in step 1, two 20-min inert gas dehydrogenation refinings are performed at intervals of more than 1 hour.

[0053] The size of the 5 series aluminum alloy ingot in step 2 is 660 mm×1610 mm×70000 mm.

[0054] The casting process parameters in step 2 are: temperature of 700°C to 730°C, casting speed of 80mm / min to 85mm / min, cooling water pressure of 0.05Mpa to 0.1Mpa, and water temperature of 10°C to 30°C.

[0055] The size of the flat ingot in step 4 is 640 mm×1610 mm×6700 mm.

[0056] The process parameters of the hot rough rolling described in step five are as follows: the rolling temperature is 445°C to 455°C, the working roll crown is set to 0.03mm, the lubricating medium concentration is 3.5% to 3.9%, UA is 3.2% to 3.6%, TE is 20% to 23%, E1 is 4.4% to 5.4%, OS is 8.2% to 8.6%, the lubricating medium temperature is 55°C to 60°C, the roller brush pressure is 5KN, the roller brush torque is 70NM, the roller brush speed is 3m / min, the roller table lubrication is turned on, the fan above the roller table is started, and the intermediate billet temperature is controlled at 360°C to 380°C.

[0057] The process parameters of hot finishing rolling described in step 6 are as follows: the inlet temperature of the finishing mill is 360℃~380℃, the concentration of the lubricating medium is 7.0%~7.5%, UA is 8.4%~8.7%, TE is 30%~32%, E1 is 2.3%~2.3%, OS is 10.0%~10.2%, ESI is 0.9%~0.93%, the temperature of the lubricating medium is 55℃~60℃, the crown of the working roll of the finishing mill is -0.005mm, the roller brush is made of steel brush material, the pressing force is set to 6.0KN, and the brush mark of the steel brush is 20m m~40mm, the average torque of the upper roller brush is 40Nm~45Nm, the average torque of the lower roller brush is 45Nm~50Nm, and the rotation speed of the roller brush is 3m / s; the average processing rate of three passes is 40%, the speed of the first pass is 2m / min, the speed of the second pass is 2m / min, and the speed of the third pass is 1.5m / min; the angle of the lubrication spray beam nozzle is adjusted to 45° counterclockwise, the spraying area of ​​the eight upper and lower spray beam nozzles at the inlet and outlet is uniformly 30mm*10mm, the nozzle is clean and free of debris, and the spray pressure of each nozzle is the same.

[0058] The final temperature of the hot finishing rolling process is controlled at 280°C to 320°C.

[0059] The process parameters of the thinning rolling described in step seven are as follows: the cold rolling temperature is 40°C to 50°C for the first pass, 70°C to 80°C for the second pass, and 100°C to 120°C for the third pass; the rolling oil viscosity is 2.50% to 2.7%, the alcohol content is 2.20% to 2.6%, the fat content is 9.37% to 9.64%, and the average pass processing rate is 30%.

[0060] The Si element content in the aluminum alloy flat ingot of this embodiment is ≤0.35%, and the Fe element content is ≤0.35%, which are derived from impurities in the aluminum ingot smelting process. The content of other single impurity elements is ≤0.05%. The impurity element content within this range has no effect on the forming performance and rolling surface of the aluminum alloy flat ingot.

[0061] The present invention eliminates black wire defects on the surface of aluminum alloy plates and strips by regulating the casting process, rolling process and lubrication process, and also provides a process technology basis and practical direction for subsequent improvement of other surface defects of aluminum alloys.

Claims

1. A preparation method for eliminating black wire defects on the surface of 5 series aluminum alloy plate and strip, characterized in that The preparation method for eliminating the black wire defect on the surface of 5 series aluminum alloy plate and strip is completed in the following steps:

1. Weighing: According to the proportion of Mg being 4.80% to 5.40%, Mn being 0.25% to 0.45%, Si≤0.35%, Fe≤0.35%, Cu≤0.35%, Fe+Si≤0.60%, Ti≤0.10%, Be being 0.0005% to 0.005% and the balance being Al, weigh remelted aluminum ingots, aluminum-manganese alloy ingots, aluminum-titanium alloy ingots, aluminum-beryllium alloy ingots and magnesium ingots as smelting raw materials; add the weighed smelting raw materials into a natural gas melting furnace according to the proportion of remelted aluminum ingots, aluminum-manganese alloy ingots, magnesium ingots and aluminum-beryllium alloy ingots for smelting to obtain aluminum alloy melt; 2. Casting the aluminum alloy melt to obtain a 5 series aluminum alloy ingot; 3. The 5 series aluminum alloy ingot is heated to 460°C to 490°C, kept at this temperature for 20h to 40h, and cooled to room temperature with the furnace to obtain a 5 series aluminum alloy ingot; Fourth, the 5 series aluminum alloy ingot is sawed to cut the head and tail pouring riser area and the cold shut area, and the oxide scale on the large surface and the end surface is milled, and the milling amount is 10-20mm to obtain a flat ingot; 5. Place the flat ingot in a heating furnace, keep it at 550°C to 560°C for 9 hours, turn it to a constant temperature of 470°C and keep it until it is taken out of the furnace for hot rough rolling, and then reduce the thickness to 23 to 25 mm by hot rough rolling to obtain an intermediate billet aluminum alloy; 6. Thinning the intermediate billet aluminum alloy to 4.0 mm to 5.5 mm by hot finish rolling to obtain a hot rolled coil billet; 7. The hot-rolled coil blank is thinned and rolled in a cold rolling mill to obtain a 5 series aluminum alloy coil blank with no black wire defects on the surface.

2. The method for eliminating black wire defects on the surface of 5 series aluminum alloy sheet and strip according to claim 1, characterized in that The smelting in step 1 is carried out at a temperature of 700° C. to 740° C. for 2 h to 4 h.

3. A method for eliminating black wire defects on the surface of 5 series aluminum alloy sheet and strip according to claim 2, characterized in that During the smelting process in step 1, two 20-min inert gas dehydrogenation refinings are performed at intervals of more than 1 hour.

4. The method for eliminating black wire defects on the surface of 5 series aluminum alloy sheet and strip according to claim 1, characterized in that The size of the 5 series aluminum alloy ingot in step 2 is 660 mm×1610 mm×70000 mm.

5. The method for eliminating black wire defects on the surface of 5 series aluminum alloy sheet and strip according to claim 1, characterized in that The casting process parameters in step 2 are: temperature of 700°C to 730°C, casting speed of 80mm / min to 85mm / min, cooling water pressure of 0.05Mpa to 0.1Mpa, and water temperature of 10°C to 30°C.

6. The method for eliminating black wire defects on the surface of 5 series aluminum alloy sheet and strip according to claim 1, characterized in that The size of the flat ingot in step 4 is 640 mm×1610 mm×6700 mm.

7. The method for eliminating black wire defects on the surface of 5 series aluminum alloy sheet and strip according to claim 1, characterized in that The process parameters of the hot rough rolling described in step five are as follows: the rolling temperature is 445°C to 455°C, the working roll crown is set to 0.03mm, the lubricating medium concentration is 3.5% to 3.9%, UA is 3.2% to 3.6%, TE is 20% to 23%, E1 is 4.4% to 5.4%, OS is 8.2% to 8.6%, the lubricating medium temperature is 55°C to 60°C, the roller brush pressure is 5KN, the roller brush torque is 70NM, the roller brush speed is 3m / min, the roller table lubrication is turned on, the fan above the roller table is started, and the intermediate billet temperature is controlled at 360°C to 380°C.

8. The method for eliminating black wire defects on the surface of 5 series aluminum alloy sheet and strip according to claim 1, characterized in that The process parameters of hot finishing rolling described in step 6 are as follows: the inlet temperature of the finishing mill is 360℃~380℃, the concentration of the lubricating medium is 7.0%~7.5%, UA is 8.4%~8.7%, TE is 30%~32%, E1 is 2.3%~2.3%, OS is 10.0%~10.2%, ESI is 0.9%~0.93%, the temperature of the lubricating medium is 55℃~60℃, the crown of the working roll of the finishing mill is -0.005mm, the roller brush is made of steel brush material, the pressing force is set to 6.0KN, and the brush mark of the steel brush is 20m m~40mm, the average torque of the upper roller brush is 40Nm~45Nm, the average torque of the lower roller brush is 45Nm~50Nm, and the rotation speed of the roller brush is 3m / s; the average processing rate of three passes is 40%, the speed of the first pass is 2m / min, the speed of the second pass is 2m / min, and the speed of the third pass is 1.5m / min; the angle of the lubrication spray beam nozzle is adjusted to 45° counterclockwise, the spraying area of ​​the eight upper and lower spray beam nozzles at the inlet and outlet is uniformly 30mm*10mm, the nozzle is clean and free of debris, and the spray pressure of each nozzle is the same.

9. The method for eliminating black wire defects on the surface of 5 series aluminum alloy sheet and strip according to claim 8, characterized in that The final temperature of the hot finishing rolling process is controlled at 280°C to 320°C.

10. The method for eliminating black wire defects on the surface of 5 series aluminum alloy sheet and strip according to claim 1, characterized in that The process parameters of the thinning rolling described in step seven are as follows: the cold rolling temperature is 40°C to 50°C for the first pass, 70°C to 80°C for the second pass, and 100°C to 120°C for the third pass; the rolling oil viscosity is 2.50% to 2.7%, the alcohol content is 2.20% to 2.6%, the fat content is 9.37% to 9.64%, and the average pass processing rate is 30%.