A production process of aluminum alloy plate

Abstract

The application relates to the field of aluminum alloy material processing and heat treatment, and discloses an aluminum alloy plate production process, which comprises the following steps: uniformly treating, rolling and solid-solution treating an aluminum alloy ingot; sending the plate after the solid-solution treatment into a partition quenching area, dividing the plate into multiple quenching partitions along the width direction of the plate, collecting cooling temperature data of each quenching partition, and determining thickness equivalent temperature data in combination with the plate thickness; determining equivalent heat history values of each quenching partition in a precipitation sensitive temperature zone according to the thickness equivalent temperature data, and adjusting the spraying intensity of the corresponding quenching partition according to the equivalent heat history values, so as to reduce the heat history difference between different quenching partitions; and when a heat history dispersion coefficient meets preset requirements, performing pre-deformation, partition pre-aging and final artificial aging treatment on the plate. The application can improve the problem of uneven quenching heat history of wide or medium-thick aluminum alloy plates.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy material processing and heat treatment, specifically to a process for producing aluminum alloy sheets. Background Technology

[0002] Aluminum alloy sheets are widely used in aerospace, transportation, machinery and equipment and structural component processing. Among them, heat-treatable aluminum alloy sheets such as 7 series usually need to undergo homogenization, rolling, solution treatment, quenching and aging treatment to obtain the required strength and formability.

[0003] In current production processes, solution-treated sheets are often subjected to uniform spraying of the entire sheet or quenching in fixed cooling stages, followed by pre-stretching, leveling, and artificial aging. While this method can meet general cooling and strengthening requirements, its spraying parameters are usually preset for the entire sheet or a fixed area, making it difficult to reflect the actual cooling differences in the width and thickness directions of the sheet in real time.

[0004] For wide or medium-thick plates, the heat dissipation conditions at the edges differ from those in the center, and the cooling rate of the surface layer also differs from that at the center of the thickness. During the quenching process, the residence state of different regions within the precipitation-sensitive temperature zone can easily vary, leading to inconsistent responses between subsequent pre-aging and artificial aging. This, in turn, causes problems such as dispersion of the width-direction properties of the plate, uneven distribution of residual stress, and decreased plate shape stability. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides an aluminum alloy sheet production process to solve the technical problems existing in the prior art.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A process for producing aluminum alloy sheets includes the following steps: S1: The aluminum alloy ingot is homogenized and rolled to obtain the plate to be solution treated; S2: Perform a solution treatment on the board material to be solution-treated to form a solution-treated board material; S3: The solution-treated plate is sent into the partitioned quenching zone and divided into three or more quenching zones along the width of the solution-treated plate. The quenching zones include the edge quenching zone and the middle quenching zone. S4: Collect the cooling temperature data of the plate area corresponding to each quenching zone, and determine the thickness equivalent temperature data of each quenching zone based on the cooling temperature data and the plate thickness. S5: Determine the equivalent thermal history value of each quenching zone in the precipitation sensitive temperature zone based on the equivalent thickness temperature data corresponding to each quenching zone. S6: Adjust the spray intensity of the corresponding quenching zone according to the equivalent thermal history value of each quenching zone to reduce the difference in equivalent thermal history value between different quenching zones. S7: After the partitioned thermal history equalization quenching is completed, determine whether the difference in equivalent thermal history values ​​between different quenching partitions does not exceed the preset difference. S8: When the difference in equivalent thermal history values ​​between different quenching zones does not exceed the preset difference, the quenched plate is pre-deformed, the pre-aging parameters are determined according to the difference in equivalent thermal history values, and the pre-deformed plate is pre-aged according to the pre-aging parameters. S9: Perform final artificial aging treatment on the pre-aged sheet material to obtain aluminum alloy sheet material.

[0007] Preferably, the aluminum alloy ingot is a 7-series aluminum alloy ingot, and the homogenization treatment includes a first homogenization treatment and a second homogenization treatment performed sequentially. The temperature of the first homogenization treatment is 430°C to 455°C and the holding time is 4h to 8h. The temperature of the second homogenization treatment is 465°C to 480°C and the holding time is 10h to 20h. The rolling process includes hot rolling, with an initial rolling temperature of 410°C to 460°C and a final rolling temperature of not less than 300°C. The solution treatment temperature is 465°C to 485°C, and the holding time is 20 min to 80 min.

[0008] Preferably, the three or more quenching zones are arranged sequentially along the width direction of the plate after solution treatment: left quenching zone, left transition quenching zone, middle quenching zone, right transition quenching zone, and right quenching zone. The widths of the left and right quenching zones are 5% to 15% of the width of the plate after solution treatment, the widths of the left and right transition quenching zones are 10% to 20% of the width of the plate after solution treatment, and the middle quenching zone is located between the left and right transition quenching zones.

[0009] Preferably, the cooling temperature data of the plate area corresponding to each quenching zone is collected separately, including: collecting temperature data on the upper and lower surfaces of the plate area corresponding to each quenching zone, with a sampling interval of 0.5s to 2s, the starting point of the collection is the moment when the plate enters the quenching zone after solution treatment, and the ending point of the collection is the moment when the temperature of the corresponding plate area is lower than the lower limit temperature of the precipitation sensitive temperature zone.

[0010] Preferably, the thickness equivalent temperature data is determined as follows: when the plate thickness is not greater than 8mm, the average value of the upper surface temperature and the lower surface temperature of the same quenching zone at the same sampling time is taken as the thickness equivalent temperature of the quenching zone at the sampling time. When the plate thickness is greater than 8mm, the thickness center temperature correction value is superimposed on the average value of the upper surface temperature and the lower surface temperature at the same sampling time in the same quenching zone to obtain the thickness equivalent temperature of the quenching zone at the sampling time. The thickness center temperature correction value is obtained in advance by measuring the thickness center temperature of the same grade and thickness sample during the quenching test.

[0011] Preferably, the precipitation sensitive temperature range is 420℃ to 180℃, and the equivalent thermal history value is determined as follows: during the process of the equivalent thickness temperature of the corresponding quenching zone entering 420℃ to below 180℃, the equivalent thickness temperature at each sampling time is read in the sampling order, and the temperature sensitivity level is determined according to the critical precipitation time corresponding to different temperatures in the continuous precipitation curve of the same grade of aluminum alloy. The shorter the critical precipitation time, the higher the corresponding temperature sensitivity level. The temperature sensitivity level corresponding to each sampling time and the sampling interval are summed to obtain the equivalent thermal history value of the corresponding quenching zone.

[0012] Preferably, adjusting the spray intensity of the corresponding quenching zone according to the equivalent thermal history value of each quenching zone includes: during the process of equalizing the thermal history of the zones, using the average value of the accumulated equivalent thermal history values ​​of multiple quenching zones as the reference thermal history value. When the accumulated equivalent thermal history value of a certain quenching zone is greater than the reference thermal history value, the water spray flow rate per unit area of ​​the quenching zone is increased. When the accumulated equivalent heat history value of a certain quenching zone is less than the reference heat history value, reduce the water spray flow rate per unit area of ​​the quenching zone. The water flow rate per unit area is adjusted by the number of nozzles opened in the corresponding quenching zone, the spray duty cycle, and the water supply pressure.

[0013] Preferably, the preset difference is the limit value of the thermal history dispersion coefficient. The thermal history dispersion coefficient is determined according to the equivalent thermal history values ​​of multiple quenching zones. The determination method is as follows: first, determine the maximum value, minimum value and average value of the equivalent thermal history values ​​of multiple quenching zones, and then take the ratio of the difference between the maximum value and the minimum value to the average value as the thermal history dispersion coefficient. When the thermal history dispersion coefficient is not greater than 0.15, the difference in equivalent thermal history values ​​between different quenching zones is determined to be no more than the preset difference.

[0014] Preferably, when the thermal history dispersion coefficient is greater than 0.15, the corresponding batch of plates is used as the parameter correction batch, the number of nozzles opened, the spray duty cycle and the water supply pressure corresponding to each quenching zone are recorded, and the spray parameters when the next batch of plates enters the zone quenching zone are corrected according to the equivalent thermal history value of each quenching zone. For quenching zones where the equivalent heat history value is greater than the average of the equivalent heat history values ​​of multiple quenching zones, increase the spray duty cycle or water supply pressure of the next batch of plates in the corresponding quenching zone. For quenching zones where the equivalent heat history value is less than the average of the equivalent heat history values ​​of multiple quenching zones, reduce the spray duty cycle or water supply pressure of the next batch of plates in the corresponding quenching zone.

[0015] Preferably, the pre-deformation treatment is carried out after the temperature of the quenched plate drops to below 35°C. The pre-deformation treatment includes longitudinal pre-stretching treatment and roller leveling treatment. The pre-stretching amount of the longitudinal pre-stretching treatment is 0.8% to 2.5%, and the single-pass reduction amount of the roller leveling treatment is 0.05% to 0.30% of the plate thickness. The pre-aging treatment is carried out in a wide-section pre-aging furnace, which has heating zones corresponding to multiple quenching zones along the width of the plate. The pre-aging parameters are determined based on the difference in equivalent thermal history values. When the thermal history dispersion coefficient is not greater than 0.10, a unified pre-aging parameter is adopted for each heating zone. The unified pre-aging parameter is to keep the temperature at 85℃ to 110℃ for 20 min to 80 min. When the thermal history dispersion coefficient is greater than 0.10 and not greater than 0.15, the baseline pre-aging parameter is to hold at 85℃ to 110℃ for 20 min to 80 min. For plate areas where the equivalent thermal history value is greater than the average of the equivalent thermal history values ​​of multiple quenching zones, a compensation pre-aging temperature 5℃ to 15℃ lower than the baseline pre-aging temperature is adopted, or a compensation pre-aging time 10 min to 30 min shorter than the baseline pre-aging time is adopted. For plate regions where the equivalent thermal history value is less than the average of the equivalent thermal history values ​​of multiple quenching zones, a compensating pre-aging temperature 5°C to 15°C higher than the reference pre-aging temperature is used, or a compensating pre-aging time 10 min to 30 min longer than the reference pre-aging time is used. The final artificial aging treatment includes a first-level artificial aging treatment and a second-level artificial aging treatment. The temperature of the first-level artificial aging treatment is 115℃ to 135℃, and the holding time is 4h to 10h. The temperature of the second-level artificial aging treatment is 155℃ to 175℃, and the holding time is 4h to 12h.

[0016] In summary, the present invention has the following main beneficial effects: This application divides the solution-treated aluminum alloy sheet into multiple quenching zones along its width, collects cooling temperature data for each zone, and determines the equivalent thickness temperature data based on the sheet thickness. Then, it uses this equivalent thickness temperature data to determine the equivalent thermal history value of each quenching zone within the precipitation-sensitive temperature zone, thereby quantifying the cooling differences at the edges, center, and thickness of the sheet. Compared to uniform spraying of the entire sheet or quenching only at fixed cooling stages, this application controls the differences in heat exposure in different width regions within the precipitation-sensitive temperature zone, providing a clear basis for subsequent spray adjustments and reducing regional microstructure differences caused by excessively rapid edge cooling, insufficient cooling in the center, or delayed cooling at the thickness center.

[0017] This application adjusts the spray intensity of the corresponding quenching zones based on their equivalent thermal history values. After the thermal history of each zone is balanced during quenching, the thermal history dispersion coefficient is used to determine the thermal history differences between different quenching zones, thereby actively converging the thermal history differences in the width direction of the sheet during the quenching stage. When the equivalent thermal history value of a certain quenching zone is too high, the spray intensity of the corresponding area is increased; when the equivalent thermal history value of a certain quenching zone is too low, the spray intensity of the corresponding area is decreased. This ensures that the cooling process of each quenching zone no longer depends on uniform spray parameters, but matches the actual thermal history state, thus helping to reduce the risks of uneven distribution of residual stress in the width direction of the sheet, sheet shape fluctuations, and inconsistent subsequent aging responses.

[0018] This application employs a wide-area pre-aging process when the thermal history dispersion coefficient is within a compensable range. It determines the compensation pre-aging temperature or time based on the deviation direction of the equivalent thermal history value of each quenching zone from the average value, thereby correcting the pre-aging starting point for different plate regions. Regions with larger equivalent thermal history values ​​use a lower or shorter compensation pre-aging regime, while regions with smaller equivalent thermal history values ​​use a higher or longer compensation pre-aging regime, making the microstructure of different wide-area regions more similar before final artificial aging. Simultaneously, when the thermal history dispersion coefficient exceeds a preset range, the corresponding batch is used as a parameter correction batch, and the zoning spray parameters for the next batch are adjusted, achieving the goal of gradually stabilizing the zoning quenching parameters during continuous production. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention.

[0020] Figure 2 This is a schematic diagram of the wide-direction partitioning of the partitioned quenching zone of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 refer to Figure 1-2 A process for producing aluminum alloy sheets includes the following steps: S1: The aluminum alloy ingot is homogenized and rolled to obtain the plate to be solution treated; S2: Perform a solution treatment on the board material to be solution-treated to form a solution-treated board material; S3: The solution-treated plate is sent into the partitioned quenching zone and divided into three or more quenching zones along the width of the solution-treated plate. The quenching zones include the edge quenching zone and the middle quenching zone. S4: Collect the cooling temperature data of the plate area corresponding to each quenching zone, and determine the thickness equivalent temperature data of each quenching zone based on the cooling temperature data and the plate thickness. S5: Determine the equivalent thermal history value of each quenching zone in the precipitation sensitive temperature zone based on the equivalent thickness temperature data corresponding to each quenching zone. S6: Adjust the spray intensity of the corresponding quenching zone according to the equivalent thermal history value of each quenching zone to reduce the difference in equivalent thermal history value between different quenching zones. S7: After the partitioned thermal history equalization quenching is completed, determine whether the difference in equivalent thermal history values ​​between different quenching partitions does not exceed the preset difference. S8: When the difference in equivalent thermal history values ​​between different quenching zones does not exceed the preset difference, the quenched plate is pre-deformed, the pre-aging parameters are determined according to the difference in equivalent thermal history values, and the pre-deformed plate is pre-aged according to the pre-aging parameters. S9: Perform final artificial aging treatment on the pre-aged sheet material to obtain aluminum alloy sheet material.

[0023] This method is suitable for heat-treated strengthened aluminum alloy sheets, especially for the production of wide or medium-thick sheets of 7-series aluminum alloys. During solution quenching, the heat dissipation conditions differ between the edges and the center of the sheet, as do the cooling states of the surface and the center of the thickness. If a uniform spray intensity is used for quenching the entire sheet, followed by uniform pre-deformation and aging treatment, different width regions may develop different thermal histories within the precipitation-sensitive temperature range, leading to inconsistencies between the initial pre-aging stage and the final artificial aging response.

[0024] The processing approach of this application is as follows: First, the solution-treated sheet is divided into multiple quenching zones along its width, and cooling temperature data of the corresponding sheet area in each quenching zone is collected. Then, the equivalent thickness temperature data is determined based on the sheet thickness, and the equivalent thermal history value of each quenching zone in the precipitation sensitive temperature zone is determined based on the equivalent thickness temperature data. Then, the spray intensity of the corresponding quenching zone is adjusted according to the equivalent thermal history value to reduce the difference in equivalent thermal history values ​​between different quenching zones. After the zone thermal history is balanced and quenched, it is determined whether the difference in equivalent thermal history values ​​between different quenching zones does not exceed a preset difference. When it does not exceed the preset difference, the quenched sheet is subjected to pre-deformation, pre-aging, and final artificial aging treatments. When it exceeds the preset difference, the corresponding batch is used as the parameter correction batch, and the zone quenching parameters of the next batch are corrected.

[0025] In this embodiment, the aluminum alloy ingot can be 7050, 7075, 7085, or 7150 aluminum alloy ingot. These grades are used to describe the objects to which the process of this application can be implemented, and are not intended to limit this application to only the aforementioned grades. For other 7xxx series aluminum alloys, as long as they have a precipitation-sensitive temperature zone and an artificial aging strengthening process after solution quenching, they can be processed according to the zoned thermal history equalization method of this application.

[0026] In this embodiment, the aluminum alloy ingot is first milled to remove the surface oxide layer and surface segregation areas. The milled aluminum alloy ingot then enters a homogenization furnace for two-stage homogenization treatment.

[0027] The temperature for the first homogenization treatment is controlled at 430℃ to 455℃, and the holding time is controlled at 4h to 8h. The temperature for the second homogenization treatment is controlled at 465℃ to 480℃, and the holding time is controlled at 10h to 20h. The first homogenization treatment is used to reduce the influence of low-melting-point segregation in the ingot on subsequent heating and deformation, while the second homogenization treatment is used to further dissolve the soluble phases inside the ingot and to stabilize the microstructure before subsequent hot rolling.

[0028] The above homogenization treatment temperature range is determined based on the composition range of the corresponding aluminum alloy grade, the melting point of the low-melting-point eutectic phase, the melting point of the main strengthening phase, and the hardness, conductivity, and metallographic test results of the trial production samples. For 7050, 7075, 7085, and 7150 aluminum alloys, the first homogenization treatment temperature is lower than the local melting temperature of the low-melting-point segregated phase, and the second homogenization treatment temperature is lower than the lower limit of the overheating temperature. Before actual production, overheating checks, grain boundary melting checks, hardness tests, and conductivity tests should be conducted on small samples or prototypes of the same aluminum alloy grade. After the above tests are passed, the specific temperature and holding time for the corresponding batch should be determined.

[0029] After homogenization, the aluminum alloy ingots are rolled. Rolling includes hot rolling, with the initial rolling temperature controlled between 410℃ and 460℃, and the final rolling temperature not lower than 300℃. During hot rolling, the reduction per pass and the total reduction rate are determined based on the target plate thickness. For plates requiring further thickness reduction, cold rolling can be performed after hot rolling; for medium-thick plates, hot rolling can be used to obtain the solution-treated plate.

[0030] The solution-treated sheet enters the solution furnace for solution treatment. The solution treatment temperature is controlled at 465℃ to 485℃, and the holding time is controlled at 20min to 80min. The solution treatment temperature is determined based on the ability to fully dissolve the soluble strengthening phase without overheating. For thicker sheets, the solution treatment is considered complete once the center of the sheet reaches the solution temperature. After solution treatment, the sheet is formed into a solution-treated sheet. The solution-treated sheet is then conveyed by a roller conveyor into the zoned quenching zone. The transfer time between the solution furnace outlet and the zoned quenching zone inlet is controlled according to the production line length and the sheet conveying speed to minimize the temperature drop before entering the quenching zone.

[0031] After solution treatment, the plate enters the partitioned quenching zone, where it is divided into three or more quenching zones along its width. Each quenching zone corresponds to a region along the width of the plate and is equipped with an independent, adjustable spray unit.

[0032] In one implementation, when the plate width is small or the number of spray units in the production line is limited, the partitioned quenching zone is divided into a left quenching zone, a middle quenching zone, and a right quenching zone along the width of the plate. The left and right quenching zones correspond to the two edge areas of the plate, respectively, while the middle quenching zone corresponds to the plate area between the two edge quenching zones. This three-zone method is used to meet the basic partitioned thermal history balance control for plates with small widths.

[0033] In another embodiment, the partitioned quenching zone is divided into five quenching zones along the width of the sheet metal: a left quenching zone, a left transition quenching zone, a middle quenching zone, a right transition quenching zone, and a right quenching zone. The widths of the left and right quenching zones are 5% to 15% of the width of the sheet metal after solution treatment. The widths of the left and right transition quenching zones are 10% to 20% of the width of the sheet metal after solution treatment. The middle quenching zone is located between the left and right transition quenching zones. This five-zone system is used to further refine the transition cooling differences between the edge and middle zones.

[0034] Each quenching zone is equipped with an upper spray assembly and a lower spray assembly. The upper spray assembly sprays towards the upper surface of the plate, and the lower spray assembly sprays towards the lower surface of the plate. Each spray assembly includes multiple nozzle groups arranged along the length of the plate. The number of nozzles opening, the spray duty cycle, and the water supply pressure can be independently controlled. The spray duty cycle refers to the proportion of the time the nozzles are open within a control cycle to the total time of that control cycle. The control cycle can be set from 0.5s to 3s, with the specific value determined based on the plate conveying speed and the nozzle response time.

[0035] The aforementioned zoning method is not simply for achieving multi-level spraying, but rather for identifying the cooling differences between the edges, transition sections, and the center of the sheet metal, and adjusting the spraying intensity of each quenching zone separately during the quenching process. This avoids the problem of excessively rapid cooling at the edges and insufficient cooling in the center when spraying the sheet metal as a whole, or excessive cooling at the edges to meet the cooling requirements of the center.

[0036] During the zone quenching process, cooling temperature data for the corresponding plate area in each quenching zone are collected. Temperature acquisition points are set on the upper and lower surfaces of the plate area corresponding to each quenching zone. Temperature acquisition can be performed using an infrared thermometer, a contact temperature sensor, or an embedded experimental temperature measurement method. For continuous production, it is preferred to use an infrared thermometer to collect the temperature of the upper and lower surfaces of the plate; during the process calibration stage, an embedded thermocouple can be used to measure the temperature at the center of the sample thickness.

[0037] The temperature sampling interval for each quenching zone is 0.5s to 2s. The sampling start point is the moment when the solution-treated plate enters the zone's quenching area, and the sampling end point is the moment when the thickness equivalent temperature of the corresponding quenching zone is lower than the lower limit temperature of the precipitation sensitive temperature zone. For 7xxx series aluminum alloys, the precipitation sensitive temperature zone is set to 420℃ to 180℃ in this embodiment. When the continuous precipitation curve of the same grade of aluminum alloy shows a shift in its precipitation sensitive temperature zone, the upper and lower limits of the precipitation sensitive temperature zone can be adjusted according to the continuous precipitation curve.

[0038] When collecting temperature data, each quenching zone should have at least one upper surface temperature acquisition point and one lower surface temperature acquisition point. When the plate width is large, more than two temperature acquisition points can be set in the same quenching zone, and the average value of the temperature acquisition points on the same side of the same quenching zone should be taken as the temperature data for that side. The temperature acquisition device is calibrated with a standard temperature source before production and compared with the results of contact temperature measurement during quenching tests. When the acquired value of a certain temperature measurement point deviates continuously from the average value of other temperature measurement points in the same quenching zone by more than the set range, the data of that temperature measurement point is not used as control data and is replaced by the average value of the remaining temperature measurement points in the same quenching zone.

[0039] After collecting the upper and lower surface temperatures, the equivalent thickness temperature data for each quenching zone is determined based on the cooling temperature data and the plate thickness.

[0040] When the plate thickness is no more than 8 mm, the temperature difference in the thickness direction has little impact on the determination of thermal history within the precipitation-sensitive temperature zone. In this embodiment, the average of the upper and lower surface temperatures of the same quenching zone at the same sampling time is taken as the thickness-direction equivalent temperature of the quenching zone at that sampling time.

[0041] When the plate thickness is greater than 8mm, the temperature drop at the center of the plate thickness usually lags behind the surface temperature. In this case, the thickness center temperature correction value is superimposed on the average value of the upper and lower surface temperatures at the same sampling time for the same quenching zone to obtain the thickness equivalent temperature of the quenching zone at that sampling time.

[0042] The thickness center temperature correction value is obtained through pre-calibration using quenching tests on samples of the same grade and thickness. During calibration, a thermocouple temperature measuring point is set at the center of the sample thickness, and temperature measuring points are simultaneously set on the upper and lower surfaces of the sample, so that the sample is quenched according to the same solution temperature, transfer method, and zoned quenching conditions as in actual production. The difference between the temperature measured at the thickness center at the same sampling time and the average temperature of the upper and lower surfaces is used as the thickness center temperature correction value for that thickness, that temperature range, and that cooling condition.

[0043] The calibration of the thickness center temperature correction value is not based on a single temperature measurement result of a single sample. For plates of the same grade and nominal thickness, at least three samples should be selected for quenching calibration tests. Thickness center temperature measurement points should be arranged at corresponding positions on the left, middle, and right sides of each sample, and the upper and lower surface temperatures should be collected simultaneously. The average value of multiple temperature measurements at the same sampling time and the same thickness position should be taken to form the thickness center temperature correction value for that grade and thickness specification.

[0044] After calibration, a correction table is created for the thickness center temperature correction value based on the sheet material grade, sheet thickness, surface cooling rate range, and sampling time. During formal production, the corresponding correction table is retrieved based on the current sheet material grade, sheet thickness, and cooling temperature data to obtain the thickness-equivalent temperature data. When the sheet thickness in formal production is not exactly the same as the calibrated sample thickness, but falls between two adjacent calibrated thicknesses, the thickness center temperature correction value can be determined by linear interpolation based on the correction values ​​corresponding to the two adjacent calibrated thicknesses. When the sheet thickness in formal production exceeds the calibrated thickness range, a new sample calibration should be performed first, and then the corresponding correction value should be retrieved.

[0045] Using the above method, the thickness-equivalent temperature is not set arbitrarily, nor is it solely inferred from surface temperature; rather, it is obtained from measured calibration data of samples of the same grade and thickness. Those skilled in the art can obtain thickness-equivalent temperature data based on the above calibration method.

[0046] In this embodiment, the equivalent thermal history value of each quenching zone within the precipitation-sensitive temperature zone is determined based on the thickness equivalent temperature data corresponding to each quenching zone. The equivalent thermal history value is used to characterize the degree of heat exposure experienced by the plate area corresponding to a certain quenching zone within the precipitation-sensitive temperature zone.

[0047] For 7-series aluminum alloys, the precipitation-sensitive temperature range is set from 420℃ to 180℃. During the process of the thickness-equivalent temperature in a certain quenching zone decreasing from 420℃ to below 180℃, the thickness-equivalent temperature is read at each sampling time according to the sampling sequence. The temperature sensitivity level is determined based on the critical precipitation time corresponding to different temperatures in the continuous precipitation curve of the same grade of aluminum alloy. The shorter the critical precipitation time, the stronger the sensitivity to unfavorable precipitation at that temperature, and the higher the corresponding temperature sensitivity level; the longer the critical precipitation time, the weaker the sensitivity to unfavorable precipitation at that temperature, and the lower the corresponding temperature sensitivity level.

[0048] Temperature sensitivity levels can be classified into five grades based on critical precipitation time. For the same grade of aluminum alloy, within the precipitation-sensitive temperature range, the critical precipitation time corresponding to each temperature point in the continuous precipitation curve is first read, and then the critical precipitation times are sorted from shortest to longest. Temperature points with critical precipitation times within the shortest 20% range are classified as Grade 5; those within the 20% to 40% range are classified as Grade 4; those within the 40% to 60% range are classified as Grade 3; those within the 60% to 80% range are classified as Grade 2; and those within the longest 20% range are classified as Grade 1.

[0049] When a continuous precipitation curve provides only a limited number of temperature points, the temperature sensitivity level between adjacent temperature points can be assigned to a range based on the levels of those adjacent temperature points. When a sampling temperature falls between two level boundaries, the level is determined by the side with the shorter critical precipitation time. Once the grading boundaries are determined, they should be consistent across production batches of the same grade and thickness specification.

[0050] The equivalent thermal history value is calculated using the following formula: ; in, For the first The equivalent thermal history value of each quenching zone; This refers to the quenching zone number; The sampling sequence number; For the first The sampling number corresponding to when the thickness equivalent temperature of each quenching zone enters the upper limit of the precipitation sensitive temperature; For the first The thickness equivalent temperature of each quenching zone is lower than the sampling sequence number corresponding to the lower limit of the precipitation sensitive temperature. For the first The first quenching zone in the first Temperature sensitivity level corresponding to each sampling time; The sampling interval is denoted as .

[0051] The temperature sensitivity level in the above formula is not arbitrarily set, but determined based on the critical precipitation time in the continuous precipitation curve of the same grade of aluminum alloy. By summing the temperature sensitivity level with the sampling interval, the residence time of the plate area in the precipitation sensitive temperature zone and the precipitation sensitivity of the temperature range can be reflected simultaneously.

[0052] During the zoned thermal history equalization quenching process, the average of the accumulated equivalent thermal history values ​​of multiple quenching zones is used as the baseline thermal history value. If the accumulated equivalent thermal history value of a certain quenching zone is greater than the baseline thermal history value, it indicates that the heat exposure of the corresponding plate area in the precipitation-sensitive temperature zone is too high, and the cooling degree is relatively insufficient; in this case, the water spray flow rate per unit area of ​​the quenching zone should be increased. If the accumulated equivalent thermal history value of a certain quenching zone is less than the baseline thermal history value, it indicates that the heat exposure of the corresponding plate area in the precipitation-sensitive temperature zone is too low, and the cooling degree is relatively strong; in this case, the water spray flow rate per unit area of ​​the quenching zone should be decreased.

[0053] The water flow rate per unit area is regulated by the number of nozzles open, the spray duty cycle, and the water supply pressure. In actual control, the spray duty cycle is adjusted first, followed by the number of nozzles open, and then the water supply pressure. If the equivalent thermal history value of a quenching zone is higher than the baseline thermal history value for two consecutive control cycles, the spray duty cycle for that quenching zone is increased; if the spray duty cycle has reached the upper limit but still cannot meet the cooling requirements, the number of nozzles open or the water supply pressure for that quenching zone is increased. If the equivalent thermal history value of a quenching zone is lower than the baseline thermal history value for two consecutive control cycles, the spray duty cycle for that quenching zone is decreased; if the spray duty cycle has reached the lower limit, the number of nozzles open or the water supply pressure for that quenching zone is decreased.

[0054] Through the above adjustment method, the change in spray intensity is not simply preset according to the width and position of the plate, nor is it executed according to a fixed multi-stage cooling system. Instead, it is adjusted based on the equivalent heat history value actually formed in each quenching zone within the precipitation sensitive temperature zone.

[0055] After the partitioned thermal history equalization quenching is completed, the thermal history dispersion coefficient between multiple quenching partitions is calculated, and the thermal history dispersion coefficient is used as the basis for judging whether the difference between the equivalent thermal history values ​​between different quenching partitions exceeds the preset difference.

[0056] The thermal history dispersion coefficient is calculated using the following formula: ; in, The thermal history dispersion coefficients; The maximum value of the equivalent thermal history value across multiple quenching zones; The minimum value of the equivalent thermal history value across multiple quenching zones; This represents the average equivalent thermal history value of multiple quenching zones.

[0057] When the thermal history dispersion coefficient is not greater than 0.15, it is determined that the difference in equivalent thermal history values ​​between different quenching zones does not exceed a preset difference, and this batch of plates proceeds to subsequent pre-deformation treatment, pre-aging treatment, and final artificial aging treatment. When the thermal history dispersion coefficient is greater than 0.15, it is determined that the difference in thermal history across the width of this batch of plates exceeds a preset difference, and this batch of plates is treated as a parameter correction batch and does not directly enter the compensation pre-aging process as a normal batch.

[0058] The thermal history dispersion coefficients of 0.10 and 0.15 were determined using trial production data of plates of the same grade and thickness. During trial production, the plates corresponding to different thermal history dispersion coefficients were divided into five testing areas along the width direction: left side, left transition, middle, right transition, and right side. Hardness, conductivity, residual stress, and plate waviness were tested in each testing area.

[0059] When the thermal history dispersion factor is no greater than 0.10, the differences in hardness, conductivity, and residual stress among the five testing areas are within the normal quality control range for the same grade of board material, therefore a unified pre-aging parameter is adopted. When the thermal history dispersion factor is greater than 0.10 but not greater than 0.15, the differences in hardness, conductivity, and residual stress among the five testing areas have exceeded the preferred control range of unified pre-aging, but the wide-dimensional performance differences after final artificial aging can still be brought back to the quality control range through zoned compensation pre-aging, therefore compensation pre-aging is adopted. When the thermal history dispersion factor is greater than 0.15, the thermal history differences among the five testing areas have exceeded the stable correction range of compensation pre-aging, therefore this batch is not directly entered into the compensation pre-aging process as a normal batch, but is used as a parameter correction batch to correct the zoned spraying parameters of the next batch of board material.

[0060] When the thermal history dispersion coefficient is greater than 0.15, the corresponding batch of plates is used as the parameter correction batch. The number of nozzles opened, the spray duty cycle and the water supply pressure corresponding to each quenching zone are recorded. The spray parameters when the next batch of plates enters the zone quenching zone are corrected according to the equivalent thermal history value of each quenching zone.

[0061] Specifically: For quenching zones with an equivalent heat history value greater than the average of the equivalent heat history values ​​of multiple quenching zones, it indicates that the heat exposure degree in the precipitation-sensitive temperature zone of this quenching zone is too high. The spray duty cycle or water supply pressure should be increased in the corresponding quenching zone for the next batch of sheet metal. For quenching zones with an equivalent heat history value less than the average of the equivalent heat history values ​​of multiple quenching zones, it indicates that the cooling in the precipitation-sensitive temperature zone of this quenching zone is too strong. The spray duty cycle or water supply pressure should be reduced in the corresponding quenching zone for the next batch of sheet metal.

[0062] In one implementation, the correction range for the spray duty cycle of the next batch is determined according to the degree of dispersion of the thermal history. When the equivalent thermal history value of a certain quenching zone deviates from the average value by no more than 5%, the spray duty cycle of that quenching zone is corrected by 1% to 3%; when the deviation is greater than 5% but not more than 10%, the spray duty cycle of that quenching zone is corrected by 3% to 6%; when the deviation is greater than 10%, the spray duty cycle of that quenching zone is corrected by 6% to 10%. The above correction range is calibrated based on nozzle response speed, plate thickness, water supply pressure stability, and production line speed.

[0063] The sheet material in the parameter correction batch is not directly processed into the pre-aging and final artificial aging processes as a normal batch. This batch can be subjected to re-solution treatment, downgraded application treatment, or experimental verification treatment according to the company's quality control requirements. When subjected to re-solution treatment, the batch of sheet material is re-supplied in the solution furnace, re-solutioned within the allowable solution temperature range for the corresponding grade, and then re-entered into the zoned quenching area. When subjected to downgraded application treatment, this batch of sheet material is not shipped as part of the target performance grade. When subjected to experimental verification treatment, this batch of sheet material is used to verify the spray parameter correction amount for the next batch.

[0064] Through the above processing, the partitioned thermal history equalization quenching is not a result judgment of a single batch, but a spray parameter correction mechanism is formed between batches, so that the partitioned quenching parameters of plates of the same grade, thickness and width are gradually stabilized in continuous production.

[0065] When the thermal history dispersion coefficient is no greater than 0.15, the quenched sheet metal undergoes pre-deformation treatment. Pre-deformation treatment is performed after the quenched sheet metal temperature drops below 35°C. If the sheet metal temperature is above 35°C, the sheet metal is still in a state of active cooling shrinkage and microstructure evolution; pre-stretching at this time will cause inconsistent deformation responses in different width regions. Therefore, this embodiment limits the pre-deformation treatment temperature to below 35°C.

[0066] Pre-deformation treatment includes longitudinal pre-stretching and roller leveling. Longitudinal pre-stretching applies tensile deformation along the length of the sheet, with a pre-stretch amount of 0.8% to 2.5%. For thinner sheets, a pre-stretch amount of 0.8% to 1.5% can be used; for medium-thick sheets, a pre-stretch amount of 1.0% to 2.5% can be used. Roller leveling is used to correct localized sheet shape fluctuations that still exist after pre-stretching; the single-pass reduction in roller leveling is 0.05% to 0.30% of the sheet thickness. After pre-deformation treatment, the sheet enters pre-aging treatment.

[0067] In this embodiment, the pre-deformation treatment is performed after the partitioned thermal history equalization quenching. Since the preceding quenching has already controlled the difference in thermal history across the width of the plate, the deformation response of different width regions is more similar during the pre-deformation treatment, which can reduce the risk of performance dispersion in subsequent pre-aging and final artificial aging.

[0068] Pre-aging treatment is carried out in a wide-section pre-aging furnace. The furnace has heating zones corresponding to multiple quenching zones along the width of the plate. Each heating zone is equipped with an independent hot air circulation assembly, heating assembly, and temperature detection assembly. Insulating baffles are installed between adjacent heating zones, maintaining a clearance between the baffles and the plate surface for plate passage. The temperature of each heating zone is controlled by the average furnace gas temperature above and below the corresponding plate area, and is verified using furnace-mounted temperature measuring instruments on the plate surface.

[0069] Before the pre-aging process begins, the control system binds each quenching zone to a heating zone of the wide-area pre-aging furnace based on the equivalent thermal history value of each quenching zone. After the sheet metal enters the wide-area pre-aging furnace, the left quenching zone corresponds to the left heating zone, the left transition quenching zone corresponds to the left transition heating zone, the middle quenching zone corresponds to the middle heating zone, the right transition quenching zone corresponds to the right transition heating zone, and the right quenching zone corresponds to the right heating zone. When using three-zone quenching, the wide-area pre-aging furnace is configured with a left heating zone, a middle heating zone, and a right heating zone.

[0070] When the thermal history dispersion coefficient is not greater than 0.10, it indicates that the equivalent thermal history values ​​between multiple quenching zones are relatively similar, and a unified pre-aging parameter is adopted for each heating zone. The unified pre-aging parameter is to hold at 85℃ to 110℃ for 20 min to 80 min.

[0071] When the thermal history dispersion coefficient is greater than 0.10 and not greater than 0.15, it indicates that there are identifiable thermal history differences among multiple quenching zones, but these differences are still within the range that can be corrected by pre-aging compensation. In this case, a holding time of 85℃ to 110℃ for 20 to 80 minutes is used as the baseline pre-aging parameter. For plate areas where the equivalent thermal history value is greater than the average equivalent thermal history value of multiple quenching zones, a compensating pre-aging temperature 5℃ to 15℃ lower than the baseline pre-aging temperature, or a compensating pre-aging time 10 to 30 minutes shorter than the baseline pre-aging time, is used. For plate areas where the equivalent thermal history value is less than the average equivalent thermal history value of multiple quenching zones, a compensating pre-aging temperature 5℃ to 15℃ higher than the baseline pre-aging temperature, or a compensating pre-aging time 10 to 30 minutes longer than the baseline pre-aging time, is used.

[0072] The basis for the above compensation direction is as follows: In plate areas with larger equivalent thermal history values, a higher degree of heat exposure has already occurred in the precipitation sensitive temperature zone during the solution quenching stage. In subsequent pre-aging, a stronger pre-aging regime should not be used in these areas, otherwise it will widen the difference in precipitation initiation between different width regions. In plate areas with smaller equivalent thermal history values, a lower degree of heat exposure has occurred during the solution quenching stage. Compensation is needed through higher pre-aging temperatures or longer pre-aging times to make their pre-aging state closer to that of other areas.

[0073] The compensation for pre-aging temperature difference and time difference was determined through comparative pre-aging tests on plates of the same grade. In the comparative tests, samples with thermal history dispersion coefficients ranging from 0.10 to 0.15 were selected, and pre-aging was performed using different compensation temperature differences and compensation time differences. Subsequently, a unified final artificial aging process was conducted, and the hardness, conductivity, and residual stress of each transverse region were measured. When the compensation temperature difference was less than 5℃ or the compensation time difference was less than 10 min, the pre-aging state convergence between transverse regions was insufficient; when the compensation temperature difference was greater than 15℃ or the compensation time difference was greater than 30 min, new aging differences were easily formed between the compensation region and the reference region. Therefore, the compensation temperature difference was limited to 5℃ to 15℃, and the compensation time difference was limited to 10 min to 30 min.

[0074] After the pre-aging treatment of the width-direction zones is completed, the boards enter the final artificial aging treatment. The final artificial aging treatment adopts a uniform aging method for the entire board, including a first-level artificial aging treatment and a second-level artificial aging treatment. The temperature for the first-level artificial aging treatment is 115℃ to 135℃, and the holding time is 4h to 10h; the temperature for the second-level artificial aging treatment is 155℃ to 175℃, and the holding time is 4h to 12h. Since the aging starting point for different areas in the width direction has been compensated in the pre-aging stage, a uniform aging system can be adopted for the final artificial aging.

[0075] Taking 7075 aluminum alloy sheet as an example, the ingot undergoes two-stage homogenization treatment after milling. The first homogenization treatment temperature is 445℃, held for 6 hours; the second homogenization treatment temperature is 470℃, held for 14 hours. After homogenization treatment, it is hot rolled at an initial rolling temperature of 440℃ and a final rolling temperature of 315℃ to obtain a 12mm thick sheet for solution treatment. The sheet is then solution treated at 475℃ for 50 minutes before entering the zoned quenching area.

[0076] The quenching zone is divided into five quenching zones along the width of the sheet metal: the left quenching zone, the left transition quenching zone, the middle quenching zone, the right transition quenching zone, and the right quenching zone. Each quenching zone is equipped with an upper spray assembly and a lower spray assembly, and infrared temperature measurement points are set on the upper and lower surfaces, respectively. The temperature sampling interval is 1 second. Since the sheet metal thickness is 12mm, which is greater than 8mm, a thickness center temperature correction value is superimposed on the average values ​​of the upper and lower surface temperatures to obtain the equivalent thickness temperature.

[0077] During the process of reducing the thickness equivalent temperature from 420℃ to 180℃, the control system reads the thickness equivalent temperature of each quenching zone in the sampling sequence and determines the temperature sensitivity level at each sampling time based on the continuous precipitation curve of 7075 aluminum alloy. Then, the temperature sensitivity level is accumulated with the sampling interval to obtain the equivalent thermal history value of each quenching zone. If the equivalent thermal history value of a certain quenching zone is higher than the reference thermal history value, the spray duty cycle of that quenching zone is increased; if the equivalent thermal history value of a certain quenching zone is lower than the reference thermal history value, the spray duty cycle of that quenching zone is decreased.

[0078] After the partitioned thermal history equalization quenching is completed, the thermal history dispersion coefficient is calculated. When the thermal history dispersion coefficient is not greater than 0.15, the plate undergoes longitudinal pre-stretching and roller leveling after the temperature drops below 35℃. The longitudinal pre-stretching amount is 1.5%, and the single-pass reduction of the roller leveling is 0.10% of the plate thickness. Subsequently, the plate enters the wide-section partitioned pre-aging furnace.

[0079] When the thermal history dispersion coefficient is not greater than 0.10, all heating zones in the wide-area pre-aging furnace adopt a unified pre-aging parameter of 100℃ for 50 min. When the thermal history dispersion coefficient is greater than 0.10 but not greater than 0.15, 100℃ for 50 min is used as the baseline pre-aging parameter. For plate areas with equivalent thermal history values ​​greater than the average, a compensating pre-aging temperature of 90℃ to 95℃ or a compensating pre-aging time of 20 min to 40 min is used; for plate areas with equivalent thermal history values ​​less than the average, a compensating pre-aging temperature of 105℃ to 110℃ or a compensating pre-aging time of 60 min to 80 min is used. After pre-aging treatment, the plates undergo primary and secondary artificial aging. The primary artificial aging temperature is 125℃ for 6 h, and the secondary artificial aging temperature is 165℃ for 8 h.

[0080] The specific temperatures and times in this production example are used to illustrate the implementation of the process in this application. For aluminum alloy sheets of different grades, thicknesses, and widths, the parameters for homogenization, solution treatment, pre-aging, and final artificial aging can be adjusted within the scope defined in the claims, but the linkage relationship between zoned thermal history equalization quenching, equivalent thermal history value judgment, thermal history dispersion coefficient judgment, and compensation pre-aging should remain consistent.

[0081] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A manufacturing process for aluminum alloy sheets, characterized in that, Includes the following steps: S1: The aluminum alloy ingot is homogenized and rolled to obtain the plate to be solution treated; S2: Perform a solution treatment on the board material to be solution-treated to form a solution-treated board material; S3: The solution-treated plate is sent into the partitioned quenching zone and divided into three or more quenching zones along the width of the solution-treated plate. The quenching zones include the edge quenching zone and the middle quenching zone. S4: Collect the cooling temperature data of the plate area corresponding to each quenching zone, and determine the thickness equivalent temperature data of each quenching zone based on the cooling temperature data and the plate thickness. S5: Determine the equivalent thermal history value of each quenching zone in the precipitation sensitive temperature zone based on the equivalent thickness temperature data corresponding to each quenching zone. S6: Adjust the spray intensity of the corresponding quenching zone according to the equivalent thermal history value of each quenching zone to reduce the difference in equivalent thermal history value between different quenching zones. S7: After the partitioned thermal history equalization quenching is completed, determine whether the difference in equivalent thermal history values ​​between different quenching partitions does not exceed the preset difference. S8: When the difference in equivalent thermal history values ​​between different quenching zones does not exceed the preset difference, the quenched plate is pre-deformed, the pre-aging parameters are determined according to the difference in equivalent thermal history values, and the pre-deformed plate is pre-aged according to the pre-aging parameters. S9: Perform final artificial aging treatment on the pre-aged sheet material to obtain aluminum alloy sheet material.

2. The aluminum alloy sheet production process according to claim 1, characterized in that, The aluminum alloy ingot is a 7-series aluminum alloy ingot. The homogenization treatment includes a first homogenization treatment and a second homogenization treatment performed sequentially. The temperature of the first homogenization treatment is 430°C to 455°C and the holding time is 4h to 8h. The temperature of the second homogenization treatment is 465°C to 480°C and the holding time is 10h to 20h. The rolling process includes hot rolling, with an initial rolling temperature of 410°C to 460°C and a final rolling temperature of not less than 300°C. The solution treatment temperature is 465°C to 485°C, and the holding time is 20 min to 80 min.

3. The aluminum alloy sheet production process according to claim 2, characterized in that, Three or more quenching zones are arranged sequentially along the width of the plate after solution treatment: left quenching zone, left transition quenching zone, middle quenching zone, right transition quenching zone, and right quenching zone. The widths of the left and right quenching zones are 5% to 15% of the width of the plate after solution treatment, the widths of the left and right transition quenching zones are 10% to 20% of the width of the plate after solution treatment, and the middle quenching zone is located between the left and right transition quenching zones.

4. The aluminum alloy sheet production process according to claim 3, characterized in that, The cooling temperature data of the corresponding plate area of ​​each quenching zone were collected separately, including: collecting temperature data on the upper and lower surfaces of the corresponding plate area of ​​each quenching zone, with a sampling interval of 0.5s to 2s. The collection start point was the moment when the plate entered the quenching zone after solution treatment, and the collection end point was the moment when the temperature of the corresponding plate area was lower than the lower limit temperature of the precipitation sensitive temperature zone.

5. The aluminum alloy sheet production process according to claim 4, characterized in that, The thickness equivalent temperature data is determined as follows: when the plate thickness is not greater than 8mm, the average value of the upper surface temperature and the lower surface temperature of the same quenching zone at the same sampling time is taken as the thickness equivalent temperature of the quenching zone at the sampling time. When the plate thickness is greater than 8mm, the thickness center temperature correction value is superimposed on the average value of the upper surface temperature and the lower surface temperature at the same sampling time in the same quenching zone to obtain the thickness equivalent temperature of the quenching zone at the sampling time. The thickness center temperature correction value is obtained in advance by measuring the thickness center temperature of the same grade and thickness sample during the quenching test.

6. The aluminum alloy sheet production process according to claim 5, characterized in that, The precipitation sensitive temperature range is 420℃ to 180℃. The equivalent thermal history value is determined as follows: During the process of the equivalent thickness temperature of the corresponding quenching zone entering from 420℃ to below 180℃, the equivalent thickness temperature at each sampling time is read in the sampling order. The temperature sensitivity level is determined according to the critical precipitation time corresponding to different temperatures in the continuous precipitation curve of the same grade of aluminum alloy. The shorter the critical precipitation time, the higher the corresponding temperature sensitivity level. The temperature sensitivity level corresponding to each sampling time and the sampling interval are summed to obtain the equivalent thermal history value of the corresponding quenching zone.

7. The aluminum alloy sheet production process according to claim 6, characterized in that, Adjusting the spray intensity of the corresponding quenching zone according to the equivalent thermal history value of each quenching zone includes: during the process of equalizing the thermal history of the zones, the average value of the accumulated equivalent thermal history values ​​of multiple quenching zones is used as the reference thermal history value. When the accumulated equivalent thermal history value of a certain quenching zone is greater than the reference thermal history value, the water spray flow rate per unit area of ​​the quenching zone is increased. When the accumulated equivalent heat history value of a certain quenching zone is less than the reference heat history value, reduce the water spray flow rate per unit area of ​​the quenching zone. The water flow rate per unit area is adjusted by the number of nozzles opened in the corresponding quenching zone, the spray duty cycle, and the water supply pressure.

8. The aluminum alloy sheet production process according to claim 7, characterized in that, The preset difference is the limit value of the thermal history dispersion coefficient. The thermal history dispersion coefficient is determined according to the equivalent thermal history values ​​of multiple quenching zones. The determination method is as follows: first, determine the maximum value, minimum value and average value of the equivalent thermal history values ​​of multiple quenching zones, and then take the ratio of the difference between the maximum value and the minimum value to the average value as the thermal history dispersion coefficient. When the thermal history dispersion coefficient is not greater than 0.15, the difference in equivalent thermal history values ​​between different quenching zones is determined to be no more than the preset difference.

9. The aluminum alloy sheet production process according to claim 8, characterized in that, When the thermal history dispersion coefficient is greater than 0.15, the corresponding batch of plates is used as the parameter correction batch. The number of nozzles opened, the spray duty cycle and the water supply pressure corresponding to each quenching zone are recorded. The spray parameters when the next batch of plates enters the zone quenching zone are corrected according to the equivalent thermal history value of each quenching zone. For quenching zones where the equivalent heat history value is greater than the average of the equivalent heat history values ​​of multiple quenching zones, increase the spray duty cycle or water supply pressure of the next batch of plates in the corresponding quenching zone. For quenching zones where the equivalent heat history value is less than the average of the equivalent heat history values ​​of multiple quenching zones, reduce the spray duty cycle or water supply pressure of the next batch of plates in the corresponding quenching zone.

10. The aluminum alloy sheet production process according to claim 9, characterized in that, The pre-deformation treatment is carried out after the temperature of the quenched plate drops below 35°C. The pre-deformation treatment includes longitudinal pre-stretching treatment and roller leveling treatment. The pre-stretching amount of the longitudinal pre-stretching treatment is 0.8% to 2.5%, and the single-pass reduction amount of the roller leveling treatment is 0.05% to 0.30% of the plate thickness. The pre-aging treatment is carried out in a wide-section pre-aging furnace, which has heating zones corresponding to multiple quenching zones along the width of the plate. The pre-aging parameters are determined based on the difference in equivalent thermal history values. When the thermal history dispersion coefficient is not greater than 0.10, a unified pre-aging parameter is adopted for each heating zone. The unified pre-aging parameter is to keep the temperature at 85℃ to 110℃ for 20 min to 80 min. When the thermal history dispersion coefficient is greater than 0.10 and not greater than 0.15, the baseline pre-aging parameter is to hold at 85℃ to 110℃ for 20 min to 80 min. For plate areas where the equivalent thermal history value is greater than the average of the equivalent thermal history values ​​of multiple quenching zones, a compensation pre-aging temperature 5℃ to 15℃ lower than the baseline pre-aging temperature is adopted, or a compensation pre-aging time 10 min to 30 min shorter than the baseline pre-aging time is adopted. For plate regions where the equivalent thermal history value is less than the average of the equivalent thermal history values ​​of multiple quenching zones, a compensating pre-aging temperature 5°C to 15°C higher than the reference pre-aging temperature is used, or a compensating pre-aging time 10 min to 30 min longer than the reference pre-aging time is used. The final artificial aging treatment includes a first-level artificial aging treatment and a second-level artificial aging treatment. The temperature of the first-level artificial aging treatment is 115℃ to 135℃, and the holding time is 4h to 10h. The temperature of the second-level artificial aging treatment is 155℃ to 175℃, and the holding time is 4h to 12h.

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