A rolling composite method based on a multilayer aluminum alloy composite plate

Abstract

The application discloses a rolling composite method based on a multilayer aluminum alloy composite plate, and comprises the following steps: S1, roughening treatment is performed on the surfaces to be composited of a first aluminum alloy plate and a second aluminum alloy plate, so that the surface roughness Ra is 6-8 microns, and the surface debris is removed through cleaning; S2, the first aluminum alloy plate, the second aluminum alloy plate and the first aluminum alloy plate are sequentially stacked, preheating is performed at 350-450 DEG C under a protective atmosphere, and the oxygen content is controlled to be less than 0.5%, and then hot composite rolling is performed at a reduction rate of 40-50%; S3, edge cracks formed at the edges of the plate after the hot composite rolling are cut off; and S4, multi-pass cold finishing rolling is performed on the composite plate after the edge cutting, and at least one intermediate annealing is performed in the cold finishing rolling process, the intermediate annealing temperature is 400-480 DEG C, and the holding time is 2-4 h.

Description

Technical Field

[0001] This invention relates to the field of metal layered composite material processing technology, and in particular to a rolling composite method based on multilayer aluminum alloy composite plates. Background Technology

[0002] Currently, aluminum alloy composite panels are metal composite materials with different grades and properties, combined into a layered structure through rolling, explosive bonding, diffusion welding, or other composite methods. Compared with single aluminum alloy sheets, layered aluminum alloy composite panels can distribute the functions of different materials along the thickness direction, allowing the surface layer to undertake functions such as electrical conductivity, thermal conductivity, corrosion resistance, or surface shaping, while the core layer undertakes functions such as strength, stiffness, or cost control. Therefore, they have application value in fields such as electronics, electrical connections, automotive lightweighting, architectural decoration, thermal management, and aerospace.

[0003] In practical engineering applications, it is often difficult to provide both high conductivity and high strength from the same aluminum alloy material. Industrial pure aluminum or near-pure aluminum materials with high conductivity usually have low yield strength and are suitable as conductive, thermally conductive, or corrosion-resistant surface layers; while magnesium-containing high-strength aluminum alloys have high strength and good work hardening ability, but their conductivity is lower than that of industrial pure aluminum.

[0004] The challenge of rolling composites of dissimilar aluminum alloys lies in the fact that different materials exhibit varying rheological stress, oxidation behavior, work hardening rates, and recrystallization behaviors during heating and rolling. The first aluminum alloy, with better electrical conductivity, typically has lower deformation resistance and is more prone to elongation during rolling; the second aluminum alloy has higher deformation resistance, making synchronous flow in the core layer more difficult. If the process window is not properly controlled, interface slippage, localized lack of bonding, edge cracking, cold-rolled delamination, or sheet instability can easily occur between the surface and core layers. Summary of the Invention

[0005] The purpose of this invention is to provide a rolling composite method based on multilayer aluminum alloy composite plates, which solves the problem of unstable bonding quality caused by rheological differences and interface oxidation between the first aluminum alloy and the second aluminum alloy during the rolling composite process, and solves the problem of the expansion of hot composite edge cracks in subsequent thin-gauge cold finishing rolling.

[0006] To achieve the above objectives, the present invention provides a rolling composite method based on multilayer aluminum alloy composite plates, comprising the following steps: S1. The surfaces of the first aluminum alloy sheet and the second aluminum alloy sheet to be composited are roughened to make the surface roughness Ra of the composite surface 6-8μm, and the roughened surfaces are cleaned and dried.

[0007] S2. Stack the first aluminum alloy sheet, the second aluminum alloy sheet, and the first aluminum alloy sheet in sequence, with the second aluminum alloy sheet located between the two layers of the first aluminum alloy sheet. Preheat the sheet at 350-450℃ in a protective atmosphere, and control the oxygen content in the protective atmosphere to be less than 0.5%. Then perform hot composite rolling with a reduction rate of 40-50%.

[0008] S3. Remove edge cracks formed on the edge of the composite plate after hot composite rolling.

[0009] S4. Perform multi-pass cold precision rolling on the trimmed composite plate, and perform at least one intermediate annealing during the multi-pass cold precision rolling process. The intermediate annealing temperature is 400-480℃, the holding time is 2-4h, and the total reduction rate of the multi-pass cold precision rolling is not less than 80%.

[0010] In some embodiments, the first aluminum alloy sheet is an industrial pure aluminum sheet, and the second aluminum alloy sheet is an Al-Mg alloy sheet. Both the first and second aluminum alloys can be sheets that have undergone annealing and softening treatment to improve plastic compatibility in the initial stage of hot composite rolling.

[0011] In some embodiments, in S1, an 80-mesh abrasive belt is used to roughen the surface to be composited, exposing the unoxidized metal substrate on the surface to be composited; the cleaning is ultrasonic cleaning.

[0012] In some embodiments, the protective atmosphere in S2 is Ar, the preheating temperature is 390-410°C, and the conveyor speed during the preheating stage is 2.5-3.5 m / min.

[0013] In some implementations, a four-roll mill is used for hot composite rolling in S2, and a six-roll mill is used for cold finishing in S4.

[0014] In some embodiments, S4 includes: performing a first cold finish rolling with a reduction of 25-35%; followed by a first intermediate annealing; performing a second cold finish rolling with a reduction of 38-45%; performing a third cold finish rolling with a reduction of 22-30%; followed by a second intermediate annealing; and performing a fourth cold finish rolling with a reduction of 30-38%.

[0015] The present invention also provides an aluminum alloy composite plate prepared by the above-described rolling composite method, comprising a first aluminum alloy surface layer, a second aluminum alloy core layer, and the first aluminum alloy surface layer. The aluminum alloy composite plate has a thickness of 0.3-1.0 mm, a conductivity of not less than 55% IACS, and a yield strength of not less than 280 MPa.

[0016] Compared with existing technologies, this invention combines surface roughening treatment with low-oxygen protective preheating, giving the surfaces to be composited both a microscopic rough structure conducive to mechanical interlocking and preventing re-oxidation of the fresh metal surface during the preheating stage. This invention preheats within the range of 350-450℃ and completes hot composite rolling at a reduction rate of 40-50%, ensuring that both the first and second aluminum alloys are in a state where they are easily coordinated in deformation, thereby reducing interfacial slip between the soft and hard materials. This invention immediately removes edge cracks after hot composite rolling, preventing subsequent cold finishing rolling from using existing edge cracks as crack sources, thus reducing the risk of strip breakage and delamination. Attached Figure Description

[0017] Figure 1 This is a process flow diagram for aluminum alloy composite panels.

[0018] Figure 2 This is a metallographic cross-section of an aluminum alloy composite plate before annealing after two passes of cold precision rolling.

[0019] Figure 3 This is a metallographic cross-section of an aluminum alloy composite plate after cold precision rolling and annealing in three passes.

[0020] Figure 4 This is a metallographic cross-section of an aluminum alloy composite plate rolled product.

[0021] Figure 5 It is a metallographic cross-section of an aluminum alloy composite plate after it has been rolled and bent.

[0022] Figure 6 This is a metallographic cross-section of an aluminum alloy after punching. Detailed Implementation

[0023] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of this application and not intended to limit it. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0024] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0025] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly or implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0026] "First aluminum alloy" refers to an aluminum-based material used to form the outer surface layer of a composite plate and having higher conductivity or better surface corrosion resistance compared to the second aluminum alloy. In some specific embodiments, the first aluminum alloy can be industrial pure aluminum or near-industrial pure aluminum, such as 1-series aluminum alloys, which have higher aluminum content, better conductivity, and lower deformation resistance.

[0027] "Second aluminum alloy" refers to an aluminum-based material located in the core layer of the composite plate and having higher strength or stronger work hardening ability compared to the first aluminum alloy. In some specific embodiments, the second aluminum alloy can be a magnesium-containing aluminum alloy, such as a 5-series aluminum alloy.

[0028] "The surface to be laminated" refers to the surface where the first aluminum alloy sheet and the second aluminum alloy sheet come into contact with each other and form an interface after being stacked. For a three-layer structure, the lower surface of the first aluminum alloy sheet on the upper side and the upper surface of the second aluminum alloy sheet on the lower side form the first interface; the upper surface of the first aluminum alloy sheet on the lower side and the lower surface of the second aluminum alloy sheet on the lower side form the second interface.

[0029] The first and second aluminum alloy sheets can be made from raw materials that have undergone complete annealing and softening treatment. This condition ensures that both sheets have good plasticity reserves before entering hot composite rolling, thereby reducing the risk of cracking during initial rolling. Especially when there is a significant difference in the rheological stress between the first and second aluminum alloys, annealing and softening treatment can reduce the abrupt constraint of the hard core layer on the soft surface layer, making the plastic deformation near the interface more continuous.

[0030] "Roughening treatment" refers to the process of removing the natural oxide film, adsorbed layer, and contaminants from the surface to be laminated using sanding belts, steel brushes, grinding rollers, or other mechanical methods, thereby creating a micron-level undulating structure on the metal surface. Roughening treatment is not simply grinding; its functions include at least three aspects: first, breaking down the original oxide film and exposing the fresh metal substrate; second, creating a certain roughness to increase the actual contact area at the interface; and third, providing microscopic interlocking points during subsequent hot lamination pressing, making it easier for localized metal exposure and mechanical interlocking to occur at the interface during plastic deformation.

[0031] A surface roughness Ra of 6-8 μm refers to the arithmetic mean deviation of the surface profile to be composited being within the range of 6-8 μm. If the roughness is too low, the surface activation is insufficient, the actual contact area at the interface is limited, and unbonded areas are prone to appear after thermal composite. If the roughness is too high, the surface peaks and valleys are too large, which can easily form local folds, inclusions, or residual voids during the pressing process, thereby reducing the continuity of the interface. Therefore, this application controls the roughness at 6-8 μm to ensure that the surface has a sufficient degree of activation while avoiding excessive roughness that could cause interface defects.

[0032] "Oxygen content less than 0.5%" means that the volume fraction of oxygen in the preheating furnace working space is less than 0.5%. This range is not intended to completely eliminate oxygen, but rather to keep the oxidation rate of the aluminum alloy surface below the critical level at which the surface activation state before thermal bonding is destroyed, so that the fresh metal surface formed by texturing can be maintained until it enters the bite zone of the rolling mill.

[0033] "Hot composite rolling" refers to the process in which, after the sheet metal is preheated, rolling mills apply pressure to deform multiple aluminum alloy sheets at the interface, causing plastic deformation, surface film breakage, metal exposure contact, micro-interlocking, and initial diffusion bonding.

[0034] "Reduction rate" refers to the percentage difference between the thickness before and after rolling relative to the thickness before rolling. When the reduction rate of hot composite rolling is 40-50%, the interface can obtain sufficient normal pressure and tangential plastic flow, so that the peak and valley structure of the roughened surface is compacted and interlocked. If the reduction rate is less than 40%, the exposed metal at the interface is not in sufficient contact, and the initial bonding strength is low. If the reduction rate is greater than 50%, the edge widening and stress concentration will increase significantly, which can easily induce edge cracks, and the soft first aluminum alloy surface layer may experience excessive flow.

[0035] "Edge trimming" refers to the operation of removing unstable areas at the edges of composite plates using a slitting machine or other cutting equipment after hot composite rolling or cold finishing. For three-layer aluminum alloy composite plates, the edges are usually the locations with the most severe widening deformation, the most complex interfacial stress state, and the easiest places for cracks to initiate. Immediate edge trimming after hot composite rolling is not simply to obtain neat edges, but to remove potential crack sources before cold finishing rolling, preventing edge cracks from propagating into the plate surface under subsequent higher cumulative reduction.

[0036] "Cold finishing rolling" refers to the rolling process at room temperature to further thin and control the shape of a composite plate after hot lamination. Cold finishing rolling not only achieves the target thickness but also further compacts the interface and improves the overall strength of the composite plate through work hardening. Because cold finishing rolling involves significant cumulative deformation, if the interface bonding is insufficient or edge cracks are not removed, the cold finishing rolling process can easily amplify previous defects.

[0037] "Intermediate annealing" refers to heat treatment of the composite plate between cold finishing rolling passes to eliminate work hardening to some extent and promote diffusion, recovery, or recrystallization processes at the interface. In this application, intermediate annealing has a dual function: on the one hand, it reduces the rolling force required for subsequent cold finishing rolling and the risk of cracking; on the other hand, it transforms the mechanically bonded interface formed in the hot composite stage into a more stable metallurgical bonding state.

[0038] "Metallurgical bonding" does not require the formation of a thick intermetallic compound layer at the interface. For systems where both the first and second aluminum alloys are aluminum-based materials, metallurgical bonding is mainly manifested in the direct metal contact between the aluminum substrates after the oxide film at the interface is broken down. During annealing, atomic diffusion and grain growth across the interface occur, thereby improving the interfacial peel strength and anti-delamination ability.

[0039] "Stretch straightening" or "stretch leveling" refers to the process of improving the shape of strip under the combined action of tension and bending deformation. Composite plates may have double-sided waviness, central waviness, or local warping after multiple rolling passes. Stretch straightening can adjust the residual stress distribution in the width direction through controlled plastic elongation, making the finished plate surface flat and suitable for subsequent punching, bonding, or precision assembly.

[0040] "Conductivity %IACS" is a relative value representing the conductivity of a material when the conductivity of the international annealed copper standard is 100%.

[0041] In this application, S1 establishes an activated interface through texturing treatment; S2 maintains the activated state through low-oxygen preheating and forms an initial bond through hot composite high-pressure; S3 removes edge defect sources through edge trimming; and S4 densifies the interface and transforms it into a metallurgical bond through cold finishing and intermediate annealing.

[0042] From the perspective of interface evolution, the surface to be composited after texturing treatment exhibits a microstructure of alternating peaks and valleys, and the oxide film and adsorption layer in the peak regions are destroyed. Upon entering the hot composite rolling bite zone, the peaks first bear significant local contact pressure and undergo plastic crushing. The surface film is torn apart and pushed outwards under shearing action, and the fresh aluminum substrate makes direct contact under high normal pressure. As the reduction rate increases, the peak-valley structure is compacted, and the local contact points gradually expand into continuous contact bands, transforming the interface from point-like interlocking to linear or planar bonding.

[0043] From the perspective of deformation coordination, the first aluminum alloy surface layer, due to its lower deformation resistance, exhibits a stronger tendency for lateral widening and longitudinal extension during thermal bonding; the second aluminum alloy core layer, due to its higher strength, constrains the surface flow. If preheating is not used to reduce the difference in deformation resistance between the two, a significant tangential velocity difference will occur at the interface, inducing relative slip and localized voids. This application utilizes low-oxygen preheating at 350-450℃ to bring both the first and second aluminum alloys into a temperature range conducive to plastic flow, reducing the flow difference without causing severe grain coarsening. This transforms the shear deformation at the interface into plastic flow that facilitates film breaking and interlocking.

[0044] During hot composite rolling, the edges of the sheet are in a free and wide state, and the metal flow at the edges is not sufficiently constrained by adjacent materials, making it easier for tensile stress concentration and microcracks to form. If these microcracks are retained until the cold finishing rolling stage, they will cause the cracks to propagate inward. This application sets the trimmed edge after hot composite rolling before cold finishing rolling, which is equivalent to removing the crack source before the defect enters the cumulative propagation stage.

[0045] The interface formed by hot composite rolling is not completely stable from the outset. Local residual oxide fragments, dislocation-dense regions, and tiny unbonded areas may still exist at the interface. Intermediate annealing causes the high-density dislocations near the interface to recover and promotes atomic diffusion between adjacent aluminum matrices; at the same time, the subsequent cold finishing rolling after annealing applies a compaction effect to the interface again, further closing the micro-regions that are not yet fully bonded.

[0046] In some embodiments, the initial thickness of the first aluminum alloy sheet is 0.5 mm, the initial thickness of the second aluminum alloy sheet is 3.5 mm, and the total thickness after stacking is 4.5 mm. This thickness distribution allows the first aluminum alloy surface layer to retain its conductivity and surface functionality in the final 0.5 mm finished product, while the second aluminum alloy core layer occupies a major proportion in the thickness direction, thereby providing sufficient load-bearing capacity. If the first aluminum alloy is too thin, the final surface conductivity and corrosion resistance will be insufficient; if the first aluminum alloy is too thick, the reinforcing effect of the second aluminum alloy core layer will decrease.

[0047] In some embodiments, the preheating temperature is around 400°C. This temperature significantly reduces the deformation resistance of the first and second aluminum alloys, making it easier for them to flow in a coordinated manner in the thermal bonding zone; at the same time, this temperature is not enough to cause abnormal grain growth or uncontrolled surface oxidation. When the preheating temperature is below 350°C, the second aluminum alloy still has high deformation resistance, and shear slip at the interface increases; when the preheating temperature is above 450°C, the surface softens excessively and the risk of oxidation increases.

[0048] In some implementations, a four-high mill is used in the hot lamination stage. The four-high mill has good reduction capacity and bite stability, making it suitable for completing the initial lamination of thick-gauge laminated sheets with large reductions. A six-high mill is used in the cold finishing stage. The six-high mill can better control the sheet shape and roll gap distribution, making it suitable for reducing edge waviness, center waviness, and thickness fluctuations in thin-gauge sections. The process transitions from four-high hot lamination to six-high cold finishing.

[0049] In some embodiments, the multi-pass cold finishing rolling includes a first cold finishing rolling reduction of approximately 30%, a second cold finishing rolling reduction of approximately 42%, a third cold finishing rolling reduction of approximately 25%, and a fourth cold finishing rolling reduction of approximately 33.3%. The intermediate annealing following the first cold finishing rolling is used to stabilize the thermal composite interface and release initial cold working stress; the second and third cold finishing rollings are used to further reduce the thickness to approximately 0.75-1.0 mm; the second intermediate annealing is used to restore some plasticity and strengthen the interface before final thin-gauge rolling; and the fourth cold finishing rolling is used to obtain a target thickness of approximately 0.5 mm.

[0050] The performance indicators in this application can be determined using the following methods. Tensile properties can be tested according to GB / T 228.1, with the specimen cut along the rolling direction, and the yield strength, tensile strength, and elongation after fracture recorded. Electrical conductivity can be tested using an eddy current conductivity meter and expressed as %IACS. Interface condition can be comprehensively judged through cross-sectional metallographic observation, bending test, or peel test. Plate shape quality can be evaluated by observing the presence of double-sided waviness, central waviness, warping, and local wrinkles, or quantitative detection can be performed using a plate shape meter.

[0051] The present invention will be further described below with reference to specific embodiments. In the following embodiments, the chemical composition of the first aluminum alloy sheet and the second aluminum alloy sheet meets the requirements of GB / T 3190. Unless otherwise stated, both the first aluminum alloy sheet and the second aluminum alloy sheet are sheets that have undergone annealing and softening treatment.

[0052] In continuous production, the method of this application can be configured as a continuous or semi-continuous production process including uncoiling, surface texturing, cleaning, protective atmosphere preheating, hot composite rolling, online trimming, cold finishing, intermediate annealing, secondary cold finishing, secondary annealing, final rolling, finished product trimming, tension leveling, and cleaning. Buffer sections or tension control sections can be set between each process according to the production cycle, but prolonged exposure of the texturized surface to be composite to air should be avoided. If the dwell time between texturing and preheating is too long, the surface to be composite will reabsorb moisture, oil mist, or oxides, thereby weakening the interfacial activation effect produced by the texturing process.

[0053] In some embodiments, the protective atmosphere preheating furnace is equipped with an oxygen content detection device, a furnace temperature detection device, and a belt conveyor speed control device. The oxygen content detection device is used to confirm that the oxygen content in the furnace is consistently below 0.5%; the furnace temperature detection device is used to avoid localized overheating or low-temperature zones; and the belt conveyor speed control device is used to ensure that the residence time of the sheet in the preheating furnace is sufficient to make the temperature in the thickness direction tend to be uniform. For laminated sheets with a total thickness of 4.0-5.0 mm, if the belt conveyor speed is too fast, the core layer temperature will lag behind the surface layer temperature, and flow differences will still occur after entering the rolling mill; if the belt conveyor speed is too slow, it may increase the risk of surface oxidation and grain growth.

[0054] In some embodiments, the inlet and outlet tensions of the hot composite rolling are controlled within a range that allows the laminated sheets to enter the rolls smoothly without causing relative slippage. If the inlet tension is too low, misalignment may occur in the three layers before entering the rolls; if the inlet tension is too high, localized stretching and thinning of the soft first aluminum alloy sheet may occur. Too low an outlet tension reduces the stability of the strip run, while too high an outlet tension may amplify newly formed interface defects. Therefore, although tension control can be achieved using conventional equipment, its purpose in this application is to maintain the continuous formation of the hot composite interface.

[0055] In some implementations, intermediate annealing employs furnace heating and furnace cooling. Furnace heating reduces thermal stress during the heating process of the composite plate, while furnace cooling reduces additional stress caused by differences in thermal expansion coefficients, work hardening degrees, and microstructure between the first aluminum alloy surface layer and the second aluminum alloy core layer during cooling. While rapid cooling can shorten production time, it may introduce new residual stresses near the interface, which is detrimental to subsequent thin-gauge cold rolling and sheet shape control.

[0056] In some implementations, the secondary trimming and tension leveling after final rolling can be adjusted according to the requirements of the finished product width, thickness, and shape. Secondary trimming primarily removes small edge fragments formed during the cold finishing stage, preventing burrs on the finished product edges from affecting subsequent punching or assembly. Tension leveling mainly improves waviness defects caused by uneven extension in the width direction. For a three-layer composite plate with a thickness of approximately 0.5 mm, even with good interfacial bonding, slight warping may occur during coiling or unwinding if the residual stress distribution is uneven. Therefore, tension leveling is a post-processing step to obtain a deliverable finished product.

[0057] Example 1 This embodiment provides a rolling composite method based on multilayer aluminum alloy composite plates. S1, The surfaces of the first aluminum alloy plate with a thickness of 0.5 mm and the second aluminum alloy plate with a thickness of 3.5 mm are roughened with 80-mesh abrasive belt to uniformly expose the unoxidized metal substrate on the surfaces to be composited, and the surface roughness Ra is controlled to be 6-8 μm. Then, the surface debris is cleaned with an ultrasonic cleaner.

[0058] S2. Stack the first aluminum alloy sheet, the second aluminum alloy sheet, and the first aluminum alloy sheet in sequence, with a total thickness of 4.5 mm after stacking. Place the second aluminum alloy sheet between the two layers of the first aluminum alloy sheet. Send the stacked sheet into a preheating furnace with a holding temperature of 400℃. Ar gas is introduced into the preheating furnace and the oxygen content is controlled to be less than 0.5%. The sheet enters the preheating furnace at a speed of 3 m / min. Then, hot composite rolling is performed using a four-roll mill. The hot composite rolling reduction rate is 45%, the thickness after rolling is 2.475 mm, and the rolling speed is 1.0 m / min.

[0059] S3. Use a slitting machine to remove edge cracks formed on the edge of the composite plate after hot composite rolling.

[0060] S4. Replace the four-high rolling mill with a six-high rolling mill. Perform the first cold finish rolling on the trimmed composite plate with a reduction rate of 30%, a thickness of 1.73 mm, and a rolling speed of 5.0 m / min. Then perform the first intermediate annealing with the furnace heating parameters of 440℃, holding for 2 hours, and furnace cooling. Perform the second cold finish rolling with a reduction rate of 42%, a thickness of 1.0 mm, and a rolling speed of 4.0 m / min. Perform the third cold finish rolling with a reduction rate of 25%, a thickness of 0.75 mm, and a rolling speed of 3.0 m / min. Then perform the second intermediate annealing with the furnace heating parameters of 440℃, holding for 2 hours, and furnace cooling. Finally, perform the fourth cold finish rolling with a reduction rate of 33.3%, a thickness of 0.5 mm, and a rolling speed of 3.0 m / min.

[0061] S5. Use a slitting machine to remove the broken edges generated during the cold finishing rolling stage at a speed of 8 m / min. S6. Use a tension leveler to straighten the composite plate after edge trimming to improve double-sided and center-sided waviness. S7. Use an ultrasonic cleaner to clean the oil stains from the surface of the tension-straightened composite plate.

[0062] Example 2 The difference between this embodiment and Embodiment 1 is that the preheating temperature in S2 is 350°C and the hot composite rolling reduction rate is 40%, in order to cover the process boundary of the lower preheating temperature and lower hot composite rolling reduction rate of this application. The remaining steps are the same as in Embodiment 1.

[0063] Example 3 The difference between this embodiment and Embodiment 1 is that the preheating temperature in S2 is 450°C and the hot composite rolling reduction rate is 50%, in order to cover the process boundaries of the higher preheating temperature and higher hot composite rolling reduction rate of this application. The remaining steps are the same as in Embodiment 1.

[0064] Example 4 The difference between this embodiment and Embodiment 1 is that the holding time for both the first and second intermediate annealing is 4 hours. The remaining steps are the same as in Embodiment 1.

[0065] Example 5 The difference between this embodiment and Embodiment 1 is that the reduction rate of the multi-pass cold finishing rolling is distributed as follows: 25% reduction rate for the first cold finishing rolling pass, 38% reduction rate for the second cold finishing rolling pass, 22% reduction rate for the third cold finishing rolling pass, and 30% reduction rate for the fourth cold finishing rolling pass. Correspondingly, the final rolling passes are adjusted according to the target thickness to make the finished product thickness approximately 1.0 mm. The remaining steps are the same as in Embodiment 1.

[0066] Example 6 The difference between this embodiment and Embodiment 1 is that the holding time for both the first and second intermediate annealing is 3 hours, the surface roughness Ra is controlled at approximately 7 μm in S1, and the tensile tension in S6 is increased by 5% compared to Embodiment 1. The remaining steps are the same as in Embodiment 1.

[0067] Comparative Example 1 The difference between this comparative example and Example 1 is that Ar gas is not introduced in S2, preheating is carried out in an air atmosphere, and the oxygen content in the preheating furnace is not controlled. The remaining steps are the same as in Example 1.

[0068] Comparative Example 2 The difference between this comparative example and Example 1 is that intermediate annealing is not performed in S4; that is, subsequent cold finishing is performed directly after the first cold finishing rolling. The remaining steps are the same as in Example 1.

[0069] Comparative Example 3 The difference between this comparative example and Example 1 is that, in S3, the edge cracks formed on the edge of the composite plate after hot composite rolling are not removed; instead, the plate directly enters the cold finishing rolling process. The remaining steps are the same as in Example 1.

[0070] Comparative Example 4 The difference between this comparative example and Example 1 is that the composite surfaces are not roughened; instead, the original surfaces are simply cleaned and then stacked. The remaining steps are the same as in Example 1.

[0071] Test Results and Analysis As can be seen from the embodiments and comparative examples, the technical effect of this application is not produced by a single step, but is jointly caused by surface roughening, low-oxygen protective preheating, high-pressure hot bonding, immediate edge trimming after hot bonding, segmented cold finishing, and intermediate annealing. Surface roughening provides an activated surface and a microscopic interlocking basis for interfacial bonding; low-oxygen protective preheating ensures that the activated surface is not re-isolated by the oxide film before hot bonding; high-pressure hot bonding enables the interface to form an initial mechanical bond; edge trimming after hot bonding blocks the propagation of edge cracks; intermediate annealing further diffuses the bonding at the interface; and cold finishing enables the composite plate to achieve the target thickness and improve its strength.

[0072] Comparative Example 1 shows that even with roughening treatment, if oxygen content is not controlled during the preheating stage, surface re-oxidation will lead to a decline in interfacial bonding quality. Comparative Example 2 shows that if the interface formed by thermal bonding is not strengthened by intermediate annealing, delamination may still occur under subsequent high-cumulative cold rolling deformation. Comparative Example 3 shows that if edge cracks formed after thermal bonding are not removed in time, they will become crack propagation sources during the cold finishing rolling stage. Comparative Example 4 shows that the original surface without roughening treatment cannot provide sufficient direct metal contact and micro-interlocking.

[0073] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A rolling composite method based on multilayer aluminum alloy composite plates, characterized in that, Includes the following steps: S1. The surfaces to be composited on the first aluminum alloy sheet and the second aluminum alloy sheet are roughened to make the surface roughness Ra of the surface to be composited 6-8μm, and the roughened surface to be composited is cleaned and dried. S2. Stack the first aluminum alloy sheet, the second aluminum alloy sheet, and the first aluminum alloy sheet in sequence, with the second aluminum alloy sheet located between the two layers of the first aluminum alloy sheet. Preheat at 350-450℃ under a protective atmosphere, and control the oxygen content in the protective atmosphere to be less than 0.5%. Then perform hot composite rolling, with a reduction rate of 40-50%. S3. Remove edge cracks formed on the edge of the composite plate after hot composite rolling; S4. Perform multi-pass cold precision rolling on the trimmed composite plate, and perform at least one intermediate annealing during the multi-pass cold precision rolling process. The intermediate annealing temperature is 400-480℃, the holding time is 2-4h, and the total reduction rate of the multi-pass cold precision rolling is not less than 80%.

2. The rolling composite method according to claim 1, characterized in that, The first aluminum alloy sheet is an industrial pure aluminum sheet, and the second aluminum alloy sheet is an Al-Mg alloy sheet.

3. The rolling composite method according to claim 2, characterized in that, In S1, an 80-mesh abrasive belt is used to roughen the surface to be composited, exposing the unoxidized metal substrate; the cleaning is ultrasonic cleaning.

4. The rolling composite method according to claim 2, characterized in that, The protective atmosphere in S2 is Ar, the preheating temperature is 390-410℃, and the conveyor speed during the preheating stage is 2.5-3.5m / min.

5. The rolling composite method according to claim 2, characterized in that, The total thickness of the first aluminum alloy plate, the second aluminum alloy plate, and the first aluminum alloy plate stacked in S2 is 4.0-5.0 mm, of which the thickness of a single layer of the first aluminum alloy plate is 0.4-0.6 mm and the thickness of the second aluminum alloy plate is 3.2-3.8 mm.

6. The rolling composite method according to claim 1, characterized in that, In S2, a four-roll mill is used for hot composite rolling at a rolling speed of 0.8-1.2 m / min; in S4, a six-roll mill is used for cold finishing rolling.

7. The rolling composite method according to claim 1, characterized in that, S4 includes: The first cold finish rolling is performed with a reduction rate of 25-35%; followed by the first intermediate annealing; and then the second cold finish rolling is performed with a reduction rate of 38-45%. The third cold finishing rolling is carried out with a reduction rate of 22-30%; followed by a second intermediate annealing; and then a fourth cold finishing rolling is carried out with a reduction rate of 30-38%.

8. The rolling composite method according to claim 7, characterized in that, The thickness after the first cold precision rolling is 1.65-1.85 mm, the thickness after the second cold precision rolling is 0.9-1.1 mm, the thickness after the third cold precision rolling is 0.70-0.80 mm, and the thickness after the fourth cold precision rolling is 0.45-0.55 mm.

9. The rolling composite method according to claim 1, characterized in that, S4 is followed by: S5. Remove the broken edges formed on the edge of the composite plate after cold precision rolling; S6. Straighten the composite board after trimming by bending; S7. Perform ultrasonic cleaning on the composite board after bending and straightening.

10. An aluminum alloy composite plate, characterized in that, The three-layer aluminum alloy composite plate is prepared by the rolling composite method according to any one of claims 1-9, comprising a first aluminum alloy surface layer, a second aluminum alloy core layer and a first aluminum alloy surface layer, wherein the thickness of the aluminum alloy composite plate is 0.3-1.0 mm, the conductivity is not less than 55% IACS, and the yield strength is not less than 280 MPa.

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