A rolling method for 0.2mm ultrathin 2xxx series aluminum alloy sheets

Abstract

A rolling method for 0.2mm ultrathin 2xxx series aluminum alloy sheets, belonging to the field of alloy technology, specifically relates to a rolling method for 0.2mm ultrathin 2xxx series aluminum alloy sheets. This invention addresses the shortcomings of existing methods in terms of surface quality, dimensional accuracy, and production efficiency. The rolling process employs multi-pass controlled rolling technology, introducing dry rolling technology and cold rolling with progressively decreasing passes, combined with optimized rolling temperature, speed, and reduction parameters. This effectively improves the thickness uniformity of the sheet and the integrated control of sheet shape and surface quality, resulting in high-quality, wide-width, and high-coil-weight 0.2mm ultrathin 2xxx series aluminum alloy sheets that highly meet the weight reduction requirements of the aerospace industry and have promising prospects for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy processing technology, specifically relating to a rolling method for 0.2mm ultrathin 2xxx series aluminum alloy sheets. Background Technology

[0002] With the rapid development of strategic emerging industries such as aerospace and high-end equipment manufacturing, the localization of core materials has become a key link in ensuring industrial self-reliance and overcoming technological barriers. Among them, 0.2mm ultra-thin 2xxx series aluminum alloy sheet is one of the core structural materials in the aerospace field, and its localization demand is particularly urgent. This invention is based on this reality and carries out relevant research.

[0003] 2xxx series aluminum alloys are heat-treatable aluminum alloys. Their main component is aluminum as the base material, with the addition of alloying elements such as copper, magnesium, and manganese. After reasonable heat treatment processes, they can obtain excellent room temperature tensile strength, yield strength, damage resistance, and fatigue resistance. At the same time, they have good machinability, weldability, and corrosion resistance. Their comprehensive performance meets the stringent requirements of the aerospace field. Therefore, they are widely used in the manufacture of various structural components such as aircraft fuselage skin, wing panels, fuselage ribs, and engine nacelle components. They are the core supporting materials for the lightweight and high-performance development of aerospace equipment.

[0004] As aerospace technology iterates and upgrades towards lightweighting, energy efficiency, and high reliability, the demand for ultra-thin sheet metal in non-critical load-bearing components of the main structure is becoming increasingly prominent. Currently, 0.2mm ultra-thin skin structural panels are widely used in non-critical load-bearing components of the main structure in the aerospace field. Compared to traditional thicknesses, this specification of ultra-thin sheet metal can effectively reduce fuselage weight, decrease fuel consumption, and improve the equipment's endurance and flight performance. Simultaneously, it can optimize structural design and improve component assembly precision and overall reliability. Meanwhile, with the rapid expansion of related industries such as civil aviation, satellite manufacturing, and high-end instrumentation, the market demand for high-quality, high-performance, and highly consistent 0.2mm ultra-thin 2xxx series aluminum alloy sheets continues to rise, providing a broad market space for the research and industrialization of this type of material.

[0005] From an international industry perspective, developed countries in Europe and America started earlier in the field of 2xxx series aluminum alloy thin sheets, and have established a complete product standard system and mature production technology, clearly covering the technical requirements and quality standards for ultra-thin sheets with a thickness of 0.2mm and below. Globally, major manufacturers include Alcoa, Kaiser Aluminum, and Issoire Rolling Mill in France, a subsidiary of Kennametal Aluminum. These companies, with their advanced rolling processes, refined process control, and mature equipment, have achieved large-scale, standardized production of ultra-thin 2xxx series aluminum alloy sheets with a thickness of 0.2mm and above. Their products not only have high dimensional accuracy, excellent surface quality, and flat sheet shape, but also good consistency in mechanical properties, stably meeting the high-end application requirements of the aerospace field and occupying a dominant position in the global high-end ultra-thin aluminum alloy sheet market.

[0006] However, the development of 0.2mm ultra-thin 2xxx series aluminum alloy sheets in China still has significant shortcomings and lags far behind international advanced levels. On the one hand, the current domestic standards for 2xxx series aluminum alloy sheets only cover medium-thick sheets with a thickness of 0.3mm to 6.0mm, and have not yet formulated clear product standards and technical specifications for 0.2mm ultra-thin specifications. This results in domestic manufacturers lacking a unified basis for quality control, leading to inconsistent product quality. On the other hand, existing domestic rolling technology and production equipment face many insurmountable technical bottlenecks in the preparation of 0.2mm ultra-thin 2xxx series aluminum alloy sheets. The most prominent problems include three main categories: difficulty in controlling surface quality, insufficient dimensional accuracy, and poor sheet shape. Specifically, during the rolling process, due to the extremely thin thickness of the sheet, even slight fluctuations in process parameters such as rolling force and rolling speed can lead to defects such as scratches, oxidation, and peeling on the sheet surface, affecting surface smoothness. At the same time, ultra-thin sheets are prone to uneven deformation during rolling, causing the sheet thickness deviation to exceed the allowable range, making it difficult to meet the dimensional accuracy requirements of the aerospace field. In addition, due to insufficient rigidity of the sheet, warping, wavy, and camber defects are prone to occur during the rolling process, seriously affecting the subsequent processing, assembly, and performance of the sheet.

[0007] The aforementioned technical problems severely restrict the industrialization and widespread application of 0.2mm ultrathin 2xxx series aluminum alloy sheets in China. This has led to a long-term reliance on imports for this specification of sheet in high-end sectors such as aerospace, increasing industrial costs and posing supply chain security risks, which is detrimental to the independent and controllable development of my country's aerospace industry. Therefore, developing a novel rolling method to specifically address the core issues of poor surface quality, insufficient dimensional accuracy, and undesirable sheet shape in existing technologies, and to achieve stable production of high-quality, wide-width, and large-coil-weight 0.2mm ultrathin 2xxx series aluminum alloy sheets, not only has significant theoretical research value, improving my country's ultrathin aluminum alloy rolling technology system and filling related technological gaps, but also has profound practical and strategic value in promoting technological progress in my country's aerospace, high-end equipment manufacturing, and other related industries, breaking international technological monopolies, achieving domestic substitution of core materials, and ensuring the security of the industrial supply chain. Summary of the Invention

[0008] The purpose of this invention is to solve the core problems existing in the prior art, such as poor surface quality, insufficient dimensional accuracy, and poor plate shape, and to provide a rolling method for 0.2mm ultrathin 2xxx series aluminum alloy plates.

[0009] The rolling method for 0.2mm ultrathin 2xxx series aluminum alloy sheet of the present invention is carried out according to the following steps:

[0010] 1. Sawing and milling the 2024 aluminum alloy ingot;

[0011] 2. Hot-roll the LB2 aluminum alloy to the designed thickness;

[0012] 3. A sandwich-structured composite ingot is obtained by welding together 2024 alloy with milled surface treatment as the core material and hot-rolled LB2 alloy as the double-sided cladding material; the thickness of the cladding material on one side is 10~40mm and the thickness of the core material is 380~410mm.

[0013] 4. The sandwich structure composite ingot is uniformly rolled into one piece; the preheating temperature of the uniform rolling is 450~500℃, and the holding time is 1400~1800min.

[0014] 5. The heated ingot is hot rolled; the hot rolling parameters are: initial rolling temperature of 430-490℃, final hot rolling thickness of 4-7.8mm, and final rolling temperature greater than 320℃.

[0015] 6. The hot-rolled sheet is then cold-rolled. The deformation per pass of the cold rolling is 15-35%. When the deformation reaches 60-80%, intermediate annealing is required. The total deformation from the final annealing to the finished product specification should be 60-85%, resulting in a rolled 0.2mm ultra-thin 2024 aluminum alloy.

[0016] The beneficial effects of this invention are:

[0017] (1) Improve production efficiency and reduce energy consumption: The integrated homogenization and rolling process combines ingot homogenization with pre-rolling heating. Compared with the traditional 2024 alloy homogenization-cooling-pre-rolling heating, the process flow time is reduced by 72~96 hours, which effectively improves production efficiency and reduces energy consumption. At the same time, it achieves the purpose of eliminating segregation and uneven structure generated during the casting process.

[0018] (2) Innovation in rolling process to improve plate quality: The introduction of dry rolling process in the hot rolling stage can ensure uniform welding of the skin and core material, avoid defects such as bubbles and cracks, and at the same time strictly control the rolling temperature and finishing speed to reduce residual stress and surface coarse grains caused by excessively low rolling temperature and excessively high speed. The introduction of a step-by-step decreasing process in the cold rolling stage ensures uniform plate thickness and stable surface quality.

[0019] (3) Breaking through thickness specifications to meet application requirements: A rolling process suitable for 0.2mm ultra-thin aluminum-clad 2xxx series alloy plates was proposed. After heat treatment, the T3 state plate has a tensile strength ≥425MPa, a yield strength ≥260MPa, and an elongation ≥15%. It also realizes the integrated control of the shape, size and surface quality of ultra-thin plates, and has good prospects for industrial application. Detailed Implementation

[0020] Specific Implementation Method 1: The rolling method for a 0.2mm ultra-thin 2xxx series aluminum alloy sheet in this implementation method is carried out according to the following steps:

[0021] 1. Sawing and milling the 2024 aluminum alloy ingot;

[0022] 2. Hot-roll the LB2 aluminum alloy to the designed thickness;

[0023] 3. A sandwich-structured composite ingot is obtained by welding together 2024 alloy with milled surface treatment as the core material and hot-rolled LB2 alloy as the double-sided cladding material; the thickness of the cladding material on one side is 10~40mm and the thickness of the core material is 380~410mm.

[0024] 4. The sandwich structure composite ingot is uniformly rolled into one piece; the preheating temperature of the uniform rolling is 450~500℃, and the holding time is 1400~1800min.

[0025] 5. The heated ingot is hot rolled; the hot rolling parameters are: initial rolling temperature of 430-490℃, final hot rolling thickness of 4-7.8mm, and final rolling temperature greater than 320℃.

[0026] 6. The hot-rolled sheet is then cold-rolled. The deformation per pass of the cold rolling is 15-35%. When the deformation reaches 60-80%, intermediate annealing is required. The total deformation from the final annealing to the finished product specification should be 60-85%, resulting in a rolled 0.2mm ultra-thin 2024 aluminum alloy.

[0027] This implementation method matches the cold rolling deformation amount with the intermediate annealing process to determine the key parameters affecting grain structure and properties, and controls the microstructure characteristics such as grain morphology and subgrain ratio of the ultrathin plate to obtain a uniform 0.2mm ultrathin cold-rolled billet. A rolling process suitable for 0.2mm ultrathin 2xxx series alloy plates is proposed, introducing dry rolling technology and a progressively decreasing cold rolling pass technology, strictly controlling the rolling temperature, rolling speed, and pass reduction to achieve integrated control of the ultrathin plate shape, dimensions, and surface quality.

[0028] This implementation adopts a double-sided aluminum structure of "LB2 alloy skin + 2024 alloy core". The LB2 alloy is pure in composition (with extremely low content of impurities such as Si, Fe, and Cu) and has a high surface finish. It can be directly used as the surface layer of the finished product, avoiding defects such as scratches and peeling caused by component segregation and oxidation during the rolling process of the 2024 alloy core. At the same time, the skin can isolate the core material from the contamination of emulsion and environmental impurities during the rolling process, thus ensuring surface quality from a structural perspective. The hot rolling stage introduces a dry rolling process (no emulsion is added in the first 5 passes) to reduce the contamination of the plate surface by emulsion residue, and avoid problems such as coarse grains and color differences caused by uneven emulsion cooling. Combined with the uniform rolling integrated process, it eliminates casting segregation and microstructure inhomogeneity, avoids rolling surface defects caused by microstructure inhomogeneity, ensures a tight weld between the skin and the core material, and eliminates interface defects such as bubbles and cracks, further improving surface integrity. The cold rolling stage adopts a progressively decreasing deformation design to avoid defects such as uneven plastic deformation and tensile damage on the surface of the sheet due to excessive deformation in a single pass. At the same time, the cold rolling speed (1.2~5.0m / s) is strictly controlled to reduce frictional damage between the sheet and the rolls during the rolling process and ensure surface smoothness.

[0029] This implementation method employs an integrated homogenization rolling process (pre-rolling heating at 450~500℃, holding for 1400~1800min) to achieve integrated homogenization of ingot casting and pre-rolling heating. This ensures uniform ingot temperature and consistent microstructure, avoiding the temperature gradient caused by the traditional "homogenization-cooling-reheating" process. This guarantees uniform deformation during rolling and reduces thickness deviation. Key parameters are strictly controlled during the hot rolling stage: initial rolling temperature 430~490℃, final rolling temperature >320℃. This prevents excessively low temperatures from increasing deformation resistance and causing uneven deformation, or excessively high temperatures from causing softening and dimensional instability. Simultaneously, the single-pass processing rate for the first five passes is controlled (1~7%) to gradually release ingot internal stress, laying the foundation for subsequent cold rolling dimensional control. The final hot-rolled thickness is precisely controlled at 4~7.8mm, ensuring dimensional consistency of the cold-rolled billet. During the cold rolling stage, intermediate annealing (320~400℃, with the holding time adjusted according to the coil weight) eliminates rolling internal stress and avoids dimensional deformation caused by stress accumulation. At the same time, by gradually reducing the deformation amount (15~35%) per pass and controlling the total deformation amount (60~85%), uniform deformation in each pass is ensured, the thickness of the sheet is precisely controlled, and the dimensional accuracy requirement of 0.2mm ultra-thin specifications is ultimately achieved.

[0030] This implementation method employs a uniform rolling integrated process and refined control of hot rolling parameters to ensure uniform ingot structure and coordinated deformation, reducing plate shape defects such as warping and wavy caused by uneven structure and stress concentration during rolling. The dry rolling process ensures a strong weld between the skin and core material, avoiding plate shape distortion due to poor interface bonding. The core technology is the progressively decreasing cold rolling pass: Ultra-thin plates lack rigidity, and excessive deformation in a single pass can lead to uneven stress distribution, resulting in defects such as camber and wavy shapes. Progressively decreasing deformation ensures stable stress distribution, gradually releasing internal stress and preventing localized stress concentration. Simultaneously, intermediate annealing eliminates accumulated stress, ensuring the plate remains flat throughout the rolling process and effectively improving plate shape. Strict control of rolling speed throughout the process (0.8~3.0 m / s for hot rolling finish and 1.2~5.0 m / s for cold rolling) avoids plate vibration and uneven stress caused by excessive speed, or excessive localized deformation caused by excessive speed, further guaranteeing plate flatness.

[0031] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the composition and weight percentage of the 2024 aluminum alloy ingot mentioned in step one are as follows: Si≤0.50%, Fe≤0.50%, Cu3.8%~4.9%, Mn0.3%~0.9%, Mg1.2%~1.8%, Cr≤0.1%, Zn≤0.25%, Ti≤0.25%, with the total content of other impurity elements not exceeding 0.15%, and the balance being Al. Everything else is the same as in Specific Implementation Method One.

[0032] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One in that the composition and weight percentage of the LB2 aluminum alloy ingot mentioned in step two are: Si≤0.30%, Fe≤0.30%, Cu≤0.01%, Mn≤0.05%, Mg≤0.05%, with the content of other impurity elements not exceeding 0.03% individually, and the balance being Al. Everything else is the same as in Specific Implementation Method One.

[0033] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method One in that the thickness of the leather material on one side in step three is 25mm, and the thickness of the core material is 395mm. Everything else is the same as in Specific Implementation Method One.

[0034] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method One in that the pre-rolling heating temperature for the uniform rolling process described in step four is 470℃, and the holding time is 1800 min. Everything else is the same as in Specific Implementation Method One.

[0035] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method One in that the pre-rolling heating temperature for the uniform rolling process described in step four is 450℃, and the holding time is 1700 min. Everything else is the same as in Specific Implementation Method One.

[0036] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method One in that the hot rolling parameters in step five are: initial rolling temperature of 460℃, final hot-rolled thickness of 5.9mm, and final rolling temperature greater than 320℃. Everything else is the same as in Specific Implementation Method One.

[0037] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method One in that the single-pass processing rate for the first 5 passes of hot rolling in step five is 1~7%, no emulsion is added, and the hot finishing rolling speed is 0.8~3.0m / s. Everything else is the same as in Specific Implementation Method One.

[0038] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method One in that the intermediate annealing temperature in step six is ​​320~400℃, and the holding time is 2~6h when the roll weight is <5t; and 6~12h when the roll weight is 5~9t. Everything else is the same as in Specific Implementation Method One.

[0039] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method One in that the cold rolling speed in step six is ​​1.2~5.0 m / s, and the reduction per cold rolling pass decreases progressively. Everything else is the same as in Specific Implementation Method One.

[0040] The beneficial effects of the present invention are verified using the following embodiments:

[0041] Example 1

[0042] In this embodiment, the 0.2mm ultra-thin 2xxx series aluminum alloy has the following composition and weight percentage for the 2024 core material: Si 0.04%, Fe 0.11%, Cu 4.84%, Mn 0.55%, Mg 1.51%, Cr 0.02%, Zn 0.12%, Ti 0.04%, with the remainder being Al; the LB2 sheath material has the following composition and weight percentage: Si 0.12%, Fe 0.22%, Cu 0.003%, Mn 0.003%, Mg 0.003%, with the remainder being Al. A milled 2024 alloy is used as the core material, and a hot-rolled LB2 alloy is used as the double-sided cladding material. These are welded together to obtain a sandwich-structured composite ingot. The sheath material has a single-sided thickness of 10mm, and the core material thickness is 410mm. The pre-rolling heating temperature was 500℃, held for 1400 min, and the initial hot rolling temperature was 490℃. The single-pass processing rates for the first five passes were 1.0%, 1.8%, 3.1%, 3.1%, and 3.5%, respectively, resulting in a final hot-rolled thickness of 4.0 mm at a final rolling temperature of 350℃. The hot-rolled coil was then cold-rolled, with single-pass deformation rates of 25%, 20%, and 15%, decreasing progressively. Intermediate annealing was performed when the total deformation reached 60%, at a temperature of 320℃ for 12 h. The final annealing brought the total deformation to 85% until the finished product specifications were achieved, resulting in a final cold-rolled thickness of 0.2 mm.

[0043] Example 2

[0044] In this embodiment, the 0.2mm ultra-thin 2xxx series aluminum alloy has the following composition and weight percentage for the 2024 core material: Si 0.04%, Fe 0.11%, Cu 4.84%, Mn 0.55%, Mg 1.51%, Cr 0.02%, Zn 0.12%, Ti 0.04%, with the remainder being Al; the LB2 sheath material has the following composition and weight percentage: Si 0.12%, Fe 0.22%, Cu 0.003%, Mn 0.003%, Mg 0.003%, with the remainder being Al. A milled 2024 alloy is used as the core material, and a hot-rolled LB2 alloy is used as the double-sided cladding material. These are welded together to obtain a sandwich-structured composite ingot. The sheath material has a single-sided thickness of 40mm, and the core material thickness is 380mm. The pre-rolling heating temperature was 470℃, held for 1800 min, and the initial hot rolling temperature was 460℃. The single-pass processing rates for the first five passes were 0.8%, 1.5%, 3.1%, 3.9%, and 5.0%, respectively, resulting in a final hot-rolled thickness of 7.8 mm at a final rolling temperature of 350℃. The hot-rolled coil was then cold-rolled, with single-pass deformation rates of 35%, 25%, and 20%, decreasing progressively. Intermediate annealing was performed when the total deformation reached 80%, at a temperature of 400℃ for 2 h. The final annealing brought the total deformation to 75% until the finished product specifications were achieved, resulting in a final cold-rolled thickness of 0.2 mm.

[0045] Example 3

[0046] In this embodiment, the 0.2mm ultra-thin 2xxx series aluminum alloy has the following composition and weight percentage for the 2024 core material: Si 0.04%, Fe 0.11%, Cu 4.84%, Mn 0.55%, Mg 1.51%, Cr 0.02%, Zn 0.12%, Ti 0.04%, with the remainder being Al; the LB2 sheath material has the following composition and weight percentage: Si 0.12%, Fe 0.22%, Cu 0.003%, Mn 0.003%, Mg 0.003%, with the remainder being Al. A milled 2024 alloy is used as the core material, and a hot-rolled LB2 alloy is used as the double-sided cladding material. These are welded together to obtain a sandwich-structured composite ingot. The sheath material has a single-sided thickness of 25mm, and the core material thickness is 395mm. The pre-rolling heating temperature was 450℃, with a holding time of 1700mm. The initial hot rolling temperature was 430℃. The single-pass processing rates for the first five passes were 1.5%, 2.7%, 3.6%, 4.2%, and 5.0%, respectively, resulting in a final hot-rolled thickness of 5.9mm. The final rolling temperature was 338℃. The hot-rolled coil was then cold-rolled, with single-pass deformation rates of 30%, 25%, and 15%, decreasing progressively. When the total deformation reached 70%, intermediate annealing was performed at 350℃ for 6 hours. The final annealing brought the total deformation to 60% until the finished product specifications were achieved, resulting in a final cold-rolled thickness of 0.2mm.

[0047] Comparative Example 1

[0048] In this embodiment, the 0.2mm ultra-thin 2xxx series aluminum alloy has the following composition and weight percentage for the 2024 core material: Si 0.04%, Fe 0.11%, Cu 4.84%, Mn 0.55%, Mg 1.51%, Cr 0.02%, Zn 0.12%, Ti 0.04%, with the remainder being Al; the LB2 sheath material has the following composition and weight percentage: Si 0.12%, Fe 0.22%, Cu 0.003%, Mn 0.003%, Mg 0.003%, with the remainder being Al. A milled 2024 alloy is used as the core material, and a hot-rolled LB2 alloy is used as the double-sided cladding material. These are welded together to obtain a sandwich-structured composite ingot. The sheath material has a single-sided thickness of 20mm, and the core material thickness is 400mm. The pre-rolling heating temperature is 450℃, with a holding time of 1550mm. The initial hot rolling temperature is 420℃. The single-pass processing rates for the first five passes are 1.0%, 1.8%, 3.1%, 3.1%, and 3.5%, respectively, resulting in a final hot-rolled thickness of 8.0mm. The final rolling temperature is 350℃. The hot-rolled coil is then cold-rolled, with single-pass deformation rates of 38%, 30%, and 15%. When the total deformation reaches 83%, intermediate annealing is performed at 380℃ for 6 hours. The final annealing completes the process until the final product specifications are achieved, with a total deformation of 60% and a final cold-rolled thickness of 0.2mm.

[0049] Comparative Example 2

[0050] In this embodiment, the 0.2mm ultra-thin 2xxx series aluminum alloy has the following composition and weight percentage for the 2024 core material: Si 0.04%, Fe 0.11%, Cu 4.84%, Mn 0.55%, Mg 1.51%, Cr 0.02%, Zn 0.12%, Ti 0.04%, with the remainder being Al; the LB2 sheath material has the following composition and weight percentage: Si 0.12%, Fe 0.22%, Cu 0.003%, Mn 0.003%, Mg 0.003%, with the remainder being Al. A milled 2024 alloy is used as the core material, and a hot-rolled LB2 alloy is used as the double-sided cladding material. These are welded together to obtain a sandwich-structured composite ingot. The sheath material has a single-sided thickness of 40mm, and the core material thickness is 380mm. The pre-rolling heating temperature was 490℃, with a holding time of 1800mm. The initial hot rolling temperature was 470℃. The single-pass processing rates for the first five passes were 1.5%, 3.1%, 4.2%, 5.3%, and 7.4%, respectively, resulting in a final hot-rolled thickness of 7.8mm. The final rolling temperature was 300℃. The hot-rolled coil was then cold-rolled, with single-pass deformation rates of 15%, 20%, and 30%. When the total deformation reached 65%, intermediate annealing was performed at 300℃ for 12 hours. The final annealing was followed by rolling to the finished product specifications, with a total deformation of 50%. The final cold-rolled thickness was 0.2mm.

[0051] Referring to Table 1, the room temperature tensile properties of 0.2 mm ultrathin 2xxx series aluminum alloy cold-rolled sheets prepared in the embodiments and comparative examples of the present invention are shown. The room temperature tensile properties of the embodiments in Table 1 are significantly better than those of the comparative examples.

[0052] Table 1. Performance of cold-rolled ultrathin sheets in the examples and comparative examples.

[0053]

Claims

1. A rolling method for 0.2mm ultrathin 2xxx series aluminum alloy sheet, characterized in that... The rolling method for 0.2mm ultra-thin 2xxx series aluminum alloy sheets is carried out according to the following steps:

1. Sawing and milling the 2024 aluminum alloy ingot; 2. Hot-roll the LB2 aluminum alloy to the designed thickness; 3. A sandwich-structured composite ingot is obtained by welding together 2024 alloy with milled surface treatment as the core material and hot-rolled LB2 alloy as the double-sided cladding material; the thickness of the cladding material on one side is 10~40mm and the thickness of the core material is 380~410mm.

4. The sandwich structure composite ingot is uniformly rolled into one piece; the preheating temperature of the uniform rolling is 450~500℃, and the holding time is 1400~1800min.

5. The heated ingot is hot rolled; the hot rolling parameters are: initial rolling temperature of 430-490℃, final hot rolling thickness of 4-7.8mm, and final rolling temperature greater than 320℃.

6. The hot-rolled sheet is then cold-rolled. The deformation per pass of the cold rolling is 15-35%. When the deformation reaches 60-80%, intermediate annealing is required. The total deformation from the final annealing to the finished product specification should be 60-85%, resulting in a rolled 0.2mm ultra-thin 2024 aluminum alloy.

2. The rolling method for a 0.2mm ultrathin 2xxx series aluminum alloy sheet according to claim 1, characterized in that... The composition and weight percentage of the 2024 aluminum alloy ingot mentioned in step one are as follows: Si≤0.50%, Fe≤0.50%, Cu3.8%~4.9%, Mn0.3%~0.9%, Mg1.2%~1.8%, Cr≤0.1%, Zn≤0.25%, Ti≤0.25%, and the total content of other impurity elements does not exceed 0.15%, with the balance being Al.

3. The rolling method for a 0.2mm ultrathin 2xxx series aluminum alloy sheet according to claim 1, characterized in that... The composition and weight percentage of the LB2 aluminum alloy ingot mentioned in step two are: Si≤0.30%, Fe≤0.30%, Cu≤0.01%, Mn≤0.05%, Mg≤0.05%, and the content of other impurity elements does not exceed 0.03% individually, with the balance being Al.

4. The rolling method for a 0.2mm ultrathin 2xxx series aluminum alloy sheet according to claim 1, characterized in that... The leather material described in step three has a single-sided thickness of 25mm and a core material thickness of 395mm.

5. The rolling method for a 0.2mm ultrathin 2xxx series aluminum alloy sheet according to claim 1, characterized in that... The pre-rolling heating temperature for the integrated rolling process described in step four is 470℃, and the holding time is 1800min.

6. The rolling method for a 0.2mm ultrathin 2xxx series aluminum alloy sheet according to claim 1, characterized in that... The pre-rolling heating temperature for the integrated rolling process described in step four is 450℃, and the holding time is 1700min.

7. The rolling method for a 0.2mm ultrathin 2xxx series aluminum alloy sheet according to claim 1, characterized in that... The hot rolling parameters mentioned in step five are: initial rolling temperature of 460℃, final hot rolling thickness of 5.9mm, and final rolling temperature greater than 320℃.

8. The rolling method for a 0.2mm ultrathin 2xxx series aluminum alloy sheet according to claim 1, characterized in that... In step five, the single-pass processing rate for the first five hot rolling passes is 1-7%, no emulsion is added, and the hot finishing rolling speed is 0.8-3.0 m / s.

9. The rolling method for a 0.2mm ultrathin 2xxx series aluminum alloy sheet according to claim 1, characterized in that... The intermediate annealing temperature in step six is ​​320~400℃. When the roll weight is <5t, the holding time is 2~6h; when the roll weight is 5~9t, the holding time is 6~12h.

10. A rolling method for a 0.2mm ultrathin 2xxx series aluminum alloy sheet according to claim 1, characterized in that... The cold rolling speed described in step six is ​​1.2~5.0 m / s, and the reduction per cold rolling pass decreases progressively.

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