Preparation method of aluminum alloy composite plate

Abstract

The present invention belongs to the technical field of metal materials, and specifically relates to an aluminum alloy composite plate and a preparation method thereof. The preparation method of the aluminum alloy composite plate comprises the following steps: (1) preparing an Al-Si-Mg alloy melt and an Al-Zr alloy melt, and then casting them respectively to obtain an Al-Si-Mg ingot and an Al-Zr ingot; (2) treating the Al-Si-Mg ingot and the Al-Zr ingot to obtain an Al-Si-Mg alloy sample and an Al-Zr alloy sample, cutting the Al-Si-Mg alloy sample and the Al-Zr alloy sample, and then performing deep cryogenic treatment and cold rolling respectively to obtain an Al-Si-Mg rolled sample plate and an Al-Zr rolled sample plate; (3) pretreating the Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate, performing powder stacking between layers of the pretreated Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate, and then performing lamination, preheating and cumulative lamination welding to obtain the aluminum alloy composite plate. The aluminum alloy composite plate prepared by the present invention has better performance, simple preparation steps and is suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal materials, and in particular relates to a method for preparing an aluminum alloy composite plate. Background Art

[0002] As the most abundant metallic element in the Earth's crust, aluminum has a wide range of practical applications after alloying. Aluminum-based aluminum-silicon alloys have excellent strength, hardness, wear resistance, corrosion resistance, and conductivity. They are commonly used in the automotive, electrical engineering, and mechanical manufacturing fields to manufacture engine parts, cylinder heads, and aluminum-core stranded wire. The prepared aluminum-core stranded wire is used in power transmission lines and to manufacture high-performance bearings, gears, and hydraulic components. Aluminum-zirconium alloys have excellent high-temperature resistance, fatigue life, and corrosion resistance, and have good application scenarios in fields such as aerospace, shipbuilding, and the chemical industry. They are often used to manufacture aircraft structures, hull structures, chemical equipment, and pipelines. Currently, the preparation of aluminum alloys is affected by the different amounts of alloying elements added. Excessive additions of alloying elements reduce the thermal stability and processability of the material and increase its brittleness. However, too low an alloying element content makes it difficult to achieve the desired effect. Aluminum silicon and aluminum zirconium alloys have different characteristics and advantages. Deep cryogenic treatment can refine the grain size of aluminum alloy, thereby improving the strength and plasticity of the material. Cumulative roll-to-roll welding can combine plates with different alloy elements to ensure that the composite plates achieve certain complementary properties. However, excessive zirconium content in aluminum zirconium alloys will cause edge cracking during rolling. In addition, the metallurgical interface of different plates after composite rolling is not tightly bonded, the actual process is cumbersome, the cost is high, and the performance of the roll-to-roll material is low, which needs to be solved urgently.

[0003] Chinese patent CN117444536A discloses a composite forming method for a coarse-grained and fine-grained layered distribution structured aluminum alloy. With the assistance of a stir friction refinement treatment, ultrasonic additive manufacturing technology is used to complete high-quality rapid consolidation forming of fine-grained aluminum foil and coarse-grained aluminum foil at room temperature or low temperature conditions, resulting in a heterogeneous aluminum alloy composed of fine-grained aluminum layers and coarse-grained aluminum layers stacked alternately, with fine-grained aluminum layers on both the upper and lower surfaces.

[0004] Chinese patent CN113290048A discloses an aluminum / magnesium / aluminum alloy composite material and a preparation process thereof, comprising the following steps: S1, material design, wherein the materials include lightweight materials, corrosion-resistant materials, and high-plasticity materials, and the design principle is that the surface of the corrosion-resistant material serves as the outer surface of the composite material, the lightweight material accounts for as large a proportion as possible while ensuring the strength of the composite material, and the high-plasticity material is designed in the area where the plasticity requirement is high; S2, material preparation, cleaning the surface of the material to be composited to ensure that there is no oxide or oil stain on the surface of the material; S3, after laminating the surfaces of the materials to be composited, simply composite the entire material; S4, placing the materials in a furnace for preheating; S5, performing multiple hot rolling composites until the material reaches the target thickness; S6, performing thermal diffusion annealing after rolling is completed to prepare a lightweight, high-plasticity aluminum / magnesium / aluminum alloy composite material.

[0005] Chinese patent CN114000182A discloses a method for preparing a metal magnesium-copper-graphene layered composite material. A plurality of magnesium sheets are pretreated, graphene is electrophoretically deposited on the pretreated magnesium sheets under the action of an external electric field, and copper powder is mechanically coated to obtain magnesium sheets with circular holes and a graphene-copper coating. After being fixed and stacked, they are wrapped and subjected to multiple cumulative hot rolling and annealing treatments to obtain a layered magnesium-based composite sheet reinforced with graphene and copper.

[0006] Among the above patents, CN117444536A uses ultrasonic additive manufacturing technology to prepare layered heterogeneous alloy plates through stir friction welding, CN113290048A uses stamping and hot rolling of composite plates to prepare magnesium / aluminum alloy composite materials, and CN114000182A uses a coating and overlapping rolling method; all three obtain composite plates with tight metallurgical bonding surfaces and excellent performance, but the equipment used in CN117444536A is expensive, and additive manufacturing technology requires controlling the influence of residual stress on the plate. CN114000182A and CN113290048A perform heat treatment processes after the plate is processed and formed, which reduces the comprehensive mechanical properties of the material. The processing process requires a high level of technology, which will increase production costs and easily cause waste of manpower and material resources.

[0007] The above patents have the problems of complex process, difficult operation, and the need for subsequent heat treatment, and the comprehensive mechanical properties and strength of the prepared plates are relatively limited. Summary of the Invention

[0008] The object of the present invention is to provide a method for preparing an aluminum alloy composite plate, wherein the prepared aluminum alloy composite plate has excellent mechanical properties, high tensile strength and overall hardness.

[0009] The technical solution adopted by the present invention to solve its technical problem is:

[0010] The method for preparing the aluminum alloy composite plate of the present invention comprises the following steps:

[0011] (1) Pure Al, pure Si and pure Mg are stirred and melted, and then kept warm and allowed to stand to prepare an Al-Si-Mg alloy melt. Pure Al and an Al-Zr master alloy are stirred and melted, and then kept warm and allowed to stand to prepare an Al-Zr alloy melt. Subsequently, they are cast to obtain Al-Si-Mg ingots and Al-Zr ingots respectively.

[0012] (2) The Al-Si-Mg ingots and Al-Zr ingots were homogenized, and then solution treated and aging treated to obtain Al-Si-Mg alloy specimens and Al-Zr alloy specimens, respectively. The Al-Si-Mg alloy specimens and Al-Zr alloy specimens were cut, and then cryogenically treated and cold rolled to obtain Al-Si-Mg rolled specimen plates and Al-Zr rolled specimen plates, respectively.

[0013] (3) The Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate are pretreated, and powder stacking is performed between the layers of the pretreated Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate, and then lamination, preheating and cumulative lamination welding are performed to obtain aluminum alloy composite plates.

[0014] in:

[0015] In the step (1), the smelting temperature is 750-790°C, the casting temperature is 220-250°C, the holding temperature is 750-790°C, and the holding time is 20-40 minutes.

[0016] In the step (2), the temperature for homogenization treatment is 515-525°C, the time for homogenization treatment is 1.9-2.1h, the temperature for solution treatment is 525-535°C, the time for solution treatment is 0.9-1.1h; the temperature for aging treatment is 238-242°C, the time for aging treatment is 15.8-16.2h.

[0017] In the step (2), the Al-Si-Mg alloy sample and the Al-Zr alloy sample are cut to a width ratio of 5-8:3-6, a length ratio of 1:1-1.5, and a thickness ratio of 1:1-1.5.

[0018] The medium for cryogenic treatment in step (2) is liquid nitrogen, the cryogenic treatment time is 4-10 h, the cold rolling reduction is 84-95%, the cold rolling passes are 5-8 times, and the thickness of the Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate are both 1.3-1.7 mm.

[0019] The mass percentages of the elements in the aluminum alloy composite plate in step (3) are Si: 4.0-5.0%, Mg: 0.2-0.8%, Zr: 0.2-1.0%, and the rest is Al.

[0020] The pretreatment in step (3) includes removing edge cracks, surface cleaning, polishing and grinding.

[0021] In the step (3), the powder stacking is to alternately and evenly stack the ultrafine Al powder with a particle size of 1-2µm and the medium Al powder with a particle size of 40-60µm between the layers of adjacent Al-Si-Mg rolled sample plates and Al-Zr rolled sample plates and compact them. The stacking area is the same as the plate area of ​​the Al-Zr rolled sample plates. The total thickness of the stacked powder after stacking and compaction is 200-500µm. The bonding is to place the Al-Zr rolled sample plate between two layers of Al-Si-Mg rolled sample plates. The preheating temperature is 545-555°C and the preheating time is 1-2min.

[0022] In the step (3), the cumulative roll-bonding welding is performed by alternating hot rolling and cold rolling, the total roll-bonding reduction is 50-90%, and the number of roll-bonding is 3-6 times.

[0023] The stack rolling is performed in two passes, the first pass is hot rolling, and the second pass is cold rolling; the stack rolling is performed by liquid nitrogen cooling for 4-10 hours immediately after hot rolling, and cold rolling is performed immediately after taking out.

[0024] The present invention mixes Si, Mg and Al, and mixes Zr and Al to form two alloy melts. After casting, the alloy melts are subjected to homogenization treatment, solution treatment and aging treatment to obtain alloy samples. A second phase is precipitated in the process of forming the alloy sample. Subsequently, deep freezing treatment, cold rolling and calendering are performed to further refine the microstructure grains. During the calendering process, coarse grains and fine grains are introduced and combined with each other to form a bimodal structure, further improving the toughness of the material. No annealing treatment is performed, which can reduce the influence of subsequent heat treatment on the performance of the plate and ensure the dislocation strengthening effect of the aluminum alloy composite plate after calendering. During the accumulative rolling process, the width of the two side rolling specimens is greater than that of the middle rolling specimen. Before accumulating rolling, ultrafine Al powder and medium Al powder are alternately layered and initially compacted between the plates. During accumulating rolling under high temperature and high pressure, the powders are melted and welded to the plates. The coarse and fine grains in the plates are squeezed, causing the positional distribution to change, which is conducive to the rapid generation of a bimodal structure, thereby improving the stiffness and strength of the plates. The excess portions of the plates on both sides are pressed together under pressure, which can prevent the middle powder from diffusing in the direction perpendicular to the rolling process, making it easier for the medium Al powder to form and maintain fibrous coarse grains. The ultrafine Al powder forms ultrafine grains distributed around the coarse grains, which work together with the fine grains in the plate to improve strength and toughness. The two passes before and after the cumulative accumulating rolling process use a method of alternating hot and cold rolling, which effectively retains the dislocation density of the accumulating plate, reduces the porosity of the microstructure formed by the powder, and further improves the performance of the plate.

[0025] Compared with the prior art, the present invention has significant advantages:

[0026] The present invention improves the performance of the resulting alloy composite sheet, reduces subsequent processing steps, and is suitable for industrial production. The advantage of the present invention lies in that the alloy sample undergoes solution treatment and aging treatment before cold rolling, eliminating the need for heat treatment after cold rolling, thus minimizing the impact of subsequent heat treatment on the sheet's performance. The precipitated dispersed second phase, Mg2Si, is evenly dispersed along the grain boundaries, hindering grain growth. The fine grains effectively reduce stress concentration and cracking, thereby enhancing the material's formability. Cryogenic treatment improves sheet processing performance, optimizing dislocation strengthening and grain refinement for different sheet types. Rolling different sheet types produces equiaxed fine grains with varying grain sizes. By making the width of the Al-Si-Mg rolled sheet larger than that of the Al-Zr rolled sheet on both sides, the movement of the powder stacked between the sheets is restricted during stacking, resulting in a bimodal structure of fibrous coarse and ultrafine grains along the rolling direction within the Al powder stacked between the sheets. A stacking method combining different powder stacking and alternating hot and cold rolling achieves metallurgical bonding of sheets with different alloying elements. Hot rolling after powder stacking ensures a tight bond between the surfaces, creating a bimodal structure. Fine grains maintain plate strength while coarse grains enhance toughness. The mixture of coarse and fine grains creates a stress-strain gradient, increasing the work hardening rate. Cold rolling ensures further formation of equiaxed fine grains of varying sizes in the Al-Si-Mg and Al-Zr rolled samples, while compacting the powder layers to reduce porosity. The microstructure at the metallurgical bond surface of the cumulative roll-bonding process is a continuous gradient-laminated-bimodal heterogeneous structure, exhibiting high strength and toughness.

[0027] Furthermore, after laminating and rolling different sheets, a high element addition content is maintained. The silicon morphology in the aluminum alloy composite sheet changes from dendritic granular silicon to spherical eutectic silicon, and the coarse Al3Zr is broken up, further ensuring a uniform distribution of the sheet's internal structure. The aluminum alloy composite sheet produced by the present invention exhibits excellent toughness and strength, possesses certain complementary properties, and features a simple and efficient rolling process, achieving excellent comprehensive mechanical and physical properties without the need for subsequent heat treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the cross-sectional structure of the Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate before rolling in Example 1;

[0029] Figure 2 Schematic diagram of the cross-section of the microstructure of the metallurgical bonding surface of the cumulative roll bonding in Example 1;

[0030] In the figure: 1. Al-Si-Mg rolled sample plate; 2. Al-Zr rolled sample plate; 3. Medium Al powder; 4. Ultra-fine Al powder; 5. Fibrous coarse grains; 6. Equiaxed ultrafine grains; 7. Al-Si-Mg equiaxed fine grains; 8. Al-Zr equiaxed fine grains. DETAILED DESCRIPTION

[0031] The present invention is further described below with reference to the following examples.

[0032] Example 1

[0033] The elements in the aluminum alloy composite plate are calculated by mass percentage, and the element composition is Si 4.0%, Mg 0.4%, Zr 0.5%, and the rest is Al.

[0034] The method for preparing an aluminum alloy composite plate comprises the following steps:

[0035] (1) Calculate the required amounts of Si, Mg and Zr according to the proportions, place the prepared pure Al in a graphite crucible of a crucible resistance furnace, heat it to 760°C and melt it, add pure Si and pure Mg in sequence, stir and melt them at 760°C, and then keep them at 760°C for 40 minutes to prepare an Al-Si-Mg alloy melt, place the prepared pure Al in a graphite crucible of a crucible resistance furnace, heat it to 760°C and melt it, add Al-Zr intermediate alloy, stir and melt them at 760°C, and then keep them at 760°C for 40 minutes to prepare an Al-Zr alloy melt, and then send them into a mold at 220°C for casting to obtain an Al-Si-Mg ingot and an Al-Zr ingot respectively;

[0036] (2) The Al-Si-Mg ingots and Al-Zr ingots were homogenized at 520 °C for 2 h, furnace cooled for 24 h and then air cooled, and then solution treated at 530 °C for 1 h, and then aged at 240 °C for 15 h to obtain Al-Si-Mg alloy samples and Al-Zr alloy samples. The Al-Si-Mg alloy samples and Al-Zr alloy samples were cut to a width ratio of 6:5, a length ratio and a thickness ratio of 1:1, and then placed in liquid nitrogen for deep freezing treatment for 8 h and then cold rolled. The cold rolling reduction was 90% and the rolling passes were 7 times to obtain Al-Si-Mg rolled sample plates and Al-Zr rolled sample plates. The thickness of the Al-Si-Mg rolled sample plates and Al-Zr rolled sample plates were both 1.5 mm.

[0037] (3) The Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate were pre-treated by removing edge cracks, surface cleaning, polishing and grinding, and then the Al-Zr rolled sample plate was placed between the two Al-Si-Mg rolled sample plates. A mold that matched the size of the Al-Zr rolled sample plate was placed on the lower Al-Si-Mg rolled sample plate and three layers of ultra-fine Al powder with a particle size of 1µm and three layers of medium Al powder with a particle size of 40µm were alternately stacked through a screen. The powder was compacted, and the Al-Zr rolled sample plate was placed in the mold and bonded. Three layers of ultra-fine Al powder with a particle size of 1µm and three layers of medium Al powder with a particle size of 40µm were alternately stacked through a screen. The powder was compacted and the mold was removed. Then the upper Al-Si-Mg rolled sample plate was placed on the compacted Al powder for bonding. The total thickness of the stacked powder after stacking and compacting was 200µm. The structure after bonding was as shown below. Figure 1 As shown, it is preheated at a temperature of 550°C for 2 minutes, and then hot rolling and cold rolling are alternately cumulatively welded, with a total rolling reduction of 50%. The rolling is repeated 5 times, and the first pass of the cumulative rolling is 25% in hot rolling reduction, followed by liquid nitrogen cooling for 6 hours. After being taken out, the second pass of cold rolling is immediately performed with a reduction of 25%, forming an aluminum alloy composite plate with an Al-Si-Mg / Al-Zr / Al-Si-Mg structure. The specific structure is shown in FIG. Figure 2 shown.

[0038] Example 2

[0039] The elements in the aluminum alloy composite plate are calculated by mass percentage, and the element composition is Si 5.0%, Mg 0.8%, Zr 1.0%, and the rest is Al.

[0040] The method for preparing an aluminum alloy composite plate comprises the following steps:

[0041] (1) Calculate the required amounts of Si, Mg and Zr according to the proportions, place the prepared pure Al in a graphite crucible of a crucible resistance furnace, heat it to 790°C and melt it, add pure Si and pure Mg in sequence, stir and melt them at 790°C, and then keep them at 790°C for 20 minutes to prepare an Al-Si-Mg alloy melt, place the prepared pure Al in a graphite crucible of a crucible resistance furnace, heat it to 790°C and melt it, add Al-Zr intermediate alloy, stir and melt them at 790°C, and then keep them at 790°C for 20 minutes to prepare an Al-Zr alloy melt, and then send them into a 250°C mold for casting to obtain an Al-Si-Mg ingot and an Al-Zr ingot respectively;

[0042] (2) The Al-Si-Mg ingots and Al-Zr ingots were homogenized at 525 °C for 2.1 h, furnace cooled for 24 h and then air cooled, and then solution treated at 530 °C for 1.1 h, and then aged at 242 °C for 16.2 h to obtain Al-Si-Mg alloy samples and Al-Zr alloy samples. The Al-Si-Mg alloy samples and Al-Zr alloy samples were cut to a width ratio of 8:6, a length ratio and a thickness ratio of 1:1.5, and then placed in liquid nitrogen for deep cryogenic treatment for 6 h and then cold rolled. The cold rolling reduction was 90%, and the rolling passes were 8 times. Al-Si-Mg rolled sample plates and Al-Zr rolled sample plates were obtained. The thickness of the Al-Si-Mg rolled sample plates and Al-Zr rolled sample plates were both 1.7 mm.

[0043] (3) The Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate were pre-treated by removing edge cracks, surface cleaning, polishing and grinding. Then, the Al-Zr rolled sample plate was placed between the two Al-Si-Mg rolled sample plates. A mold that matched the size of the Al-Zr rolled sample plate was placed on the lower Al-Si-Mg rolled sample plate, and three layers of ultra-fine Al powder with a particle size of 2 μm and three layers of medium Al powder with a particle size of 60 μm were alternately stacked through a screen. The powder was compacted, and the Al-Zr rolled sample plate was placed in the mold and fitted. Then, three layers of ultra-fine Al powder with a particle size of 1 μm and three layers of medium Al powder with a particle size of 40 μm were alternately stacked through a screen. μm medium Al powder is compacted and removed from the mold. The upper Al-Si-Mg rolled sample plate is then placed on the compacted Al powder for bonding. The total thickness of the stacked powder after piling and compaction is 500μm. It is then preheated at 555℃ for 2 minutes, and then hot rolling and cold rolling are alternately performed. The total rolling reduction is 90%, and the rolling is repeated 6 times. The first hot rolling reduction of the cumulative rolling is 60%, and then it is immediately cooled with liquid nitrogen for 10 hours. After being taken out, the second cold rolling is immediately performed with a reduction of 30% to form an aluminum alloy composite plate with an Al-Si-Mg / Al-Zr / Al-Si-Mg structure.

[0044] Example 3

[0045] The elements in the aluminum alloy composite plate are Si 4.0%, Mg 0.2%, Zr 1.0%, and the rest is Al, calculated by mass percentage.

[0046] The method for preparing an aluminum alloy composite plate comprises the following steps:

[0047] (1) Calculate the required amounts of Si, Mg and Zr according to the proportions, place the prepared pure Al in a graphite crucible of a crucible resistance furnace, heat it to 750°C and melt it, add pure Si and pure Mg in sequence, stir and melt them at 750°C, and then keep them at 750°C and let them stand for 40 minutes to prepare an Al-Si-Mg alloy melt, place the prepared pure Al in a graphite crucible of a crucible resistance furnace, heat it to 750°C and melt it, add Al-Zr intermediate alloy, stir and melt them at 750°C, and then keep them at 750°C and let them stand for 40 minutes to prepare an Al-Zr alloy melt, and then send them into a 250°C mold for casting to obtain an Al-Si-Mg ingot and an Al-Zr ingot respectively;

[0048] (2) The Al-Si-Mg ingots and Al-Zr ingots were homogenized at 515 °C for 2 h, furnace cooled for 24 h and then air cooled, and then solution treated at 525 °C for 0.9 h, and then aged at 238 °C for 15.8 h to obtain Al-Si-Mg alloy samples and Al-Zr alloy samples. The Al-Si-Mg alloy samples and Al-Zr alloy samples were cut to a width ratio of 6:5, a length ratio and a thickness ratio of 1:1, and then placed in liquid nitrogen for deep cryogenic treatment for 4 h and then cold rolled. The cold rolling reduction was 84% ​​and the rolling passes were 8 times. Al-Si-Mg rolled sample plates and Al-Zr rolled sample plates were obtained. The thickness of the Al-Si-Mg rolled sample plates and Al-Zr rolled sample plates were both 1.3 mm.

[0049] (3) The Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate were pre-treated by removing edge cracks, surface cleaning, polishing and grinding. Then, the Al-Zr rolled sample plate was placed between the two Al-Si-Mg rolled sample plates. A mold that matched the size of the Al-Zr rolled sample plate was placed on the lower Al-Si-Mg rolled sample plate, and three layers of ultra-fine Al powder with a particle size of 2 μm and three layers of medium Al powder with a particle size of 50 μm were alternately stacked through a screen. The powder was compacted, and the Al-Zr rolled sample plate was placed in the mold and fitted. Then, three layers of ultra-fine Al powder with a particle size of 1 μm and three layers of medium Al powder with a particle size of 40 μm were alternately stacked through a screen. m medium Al powder, compact the powder and remove the mold, then place the upper Al-Si-Mg rolled sample plate on the compacted Al powder for bonding, the total thickness of the stacked powder after piling and compaction is 400µm, and then preheat it at 545℃ for 1min, then perform alternating hot rolling and cold rolling and cumulative lamination welding, with a total lamination reduction of 90%, and lamination for 6 times, the first pass of cumulative lamination has a hot rolling reduction of 60% and then immediately liquid nitrogen cooling for 10h, and immediately perform a second cold rolling with a reduction of 30% after taking out, to form an aluminum alloy composite plate with Al-Si-Mg / Al-Zr / Al-Si-Mg structure.

[0050] Example 4

[0051] The elements in the aluminum alloy composite plate are Si 4.2%, Mg 0.2%, Zr 0.2%, and the rest is Al, calculated by mass percentage.

[0052] The method for preparing an aluminum alloy composite plate comprises the following steps:

[0053] (1) Calculate the required amounts of Si, Mg and Zr according to the proportions, place the prepared pure Al in a graphite crucible of a crucible resistance furnace, heat it to 760°C and melt it, add pure Si and pure Mg in sequence, stir and melt them at 760°C, and then keep them at 760°C for 30 minutes to prepare an Al-Si-Mg alloy melt, place the prepared pure Al in a graphite crucible of a crucible resistance furnace, heat it to 760°C and melt it, add Al-Zr intermediate alloy, stir and melt them at 760°C, and then keep them at 760°C for 40 minutes to prepare an Al-Zr alloy melt, and then send them into a mold at 230°C for casting to obtain an Al-Si-Mg ingot and an Al-Zr ingot respectively;

[0054] (2) The Al-Si-Mg ingots and Al-Zr ingots were homogenized at 520 °C for 2 h, furnace cooled for 24 h and then air cooled, and then solution treated at 530 °C for 1 h, and then aged at 240 °C for 15.9 h to obtain Al-Si-Mg alloy samples and Al-Zr alloy samples. The Al-Si-Mg alloy samples and Al-Zr alloy samples were cut to a width ratio of 5:3, a length ratio and a thickness ratio of 1:1.2, and then placed in liquid nitrogen for deep freezing treatment for 8 h and then cold rolled. The cold rolling reduction was 95% and the rolling passes were 6 times. Al-Si-Mg rolled sample plates and Al-Zr rolled sample plates were obtained. The thickness of the Al-Si-Mg rolled sample plates and Al-Zr rolled sample plates were both 1.5 mm.

[0055] (3) The Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate were pre-treated by removing edge cracks, surface cleaning, polishing and grinding. Then, the Al-Zr rolled sample plate was placed between the two Al-Si-Mg rolled sample plates. A mold that matched the size of the Al-Zr rolled sample plate was placed on the lower Al-Si-Mg rolled sample plate, and three layers of ultra-fine Al powder with a particle size of 2 μm and three layers of medium Al powder with a particle size of 60 μm were alternately stacked through a screen. The powder was compacted, and the Al-Zr rolled sample plate was placed in the mold and fitted. Then, three layers of ultra-fine Al powder with a particle size of 1 μm and three layers of medium Al powder with a particle size of 40 μm were alternately stacked through a screen. μm medium Al powder is compacted and removed from the mold. The upper Al-Si-Mg rolled sample plate is then placed on the compacted Al powder for bonding. The total thickness of the stacked powder after piling and compaction is 300μm. It is preheated at 550℃ for 2min, and then hot rolling and cold rolling are alternately performed for cumulative lamination welding. The total lamination reduction is 50%. Lamination is performed 5 times. The first pass of cumulative lamination has a hot rolling reduction of 40% and then immediately liquid nitrogen cooling for 10h. After being taken out, the second pass of cold rolling is immediately performed with a reduction of 1% to form an aluminum alloy composite plate with an Al-Si-Mg / Al-Zr / Al-Si-Mg structure.

[0056] Comparative Example 1

[0057] The element composition of the prepared composite plate is Si 4.0%, Mg 0.4%, and the rest is Al.

[0058] (1) Calculate the required amount of Si and Mg according to the ratio, place the prepared pure Al in a graphite crucible of a crucible resistance furnace, heat it to 760°C and melt it, then add pure Si and pure Mg in sequence, stir and melt them at 760°C, keep them at 760°C and let them stand for 40 minutes to prepare an Al-Si-Mg alloy melt, which is then put into a mold at 220°C for casting to obtain an Al-Si-Mg ingot;

[0059] (2) The Al-Si-Mg ingot was homogenized at 520°C for 2 h, furnace cooled for 24 h and then air-cooled, then solution treated at 530°C for 1 h, and then aged at 240°C for 15 h to obtain Al-Si-Mg alloy samples. The Al-Si-Mg alloy samples were cut to a width ratio of 6:5, a length ratio and a thickness ratio of 1:1, and then placed in liquid nitrogen for deep cryogenic treatment for 8 h and then cold rolled. The cold rolling reduction was 90% and the rolling passes were 7 times to obtain Al-Si-Mg rolled sample plates. The thickness of the Al-Si-Mg rolled sample plates was 1.5 mm.

[0060] (3) The Al-Si-Mg rolled sample plate is pre-treated by removing edge cracks, surface cleaning, polishing and grinding, and then the three layers of Al-Si-Mg rolled sample plates are bonded. A mold that matches the size of the middle layer Al-Si-Mg rolled sample plate is placed on the lower layer Al-Si-Mg rolled sample plate, and three layers of ultra-fine Al powder with a particle size of 1µm and three layers of medium Al powder with a particle size of 40µm are alternately stacked through a screen. The powder is compacted, and the middle layer Al-Si-Mg rolled sample plate is placed in the mold and bonded. Three layers of ultra-fine Al powder with a particle size of 1µm and three layers of medium Al powder with a particle size of 40µm are alternately stacked through a screen. The medium Al powder is 40µm, the powder is compacted and the mold is removed, and then the upper Al-Si-Mg rolled sample plate is placed on the compacted Al powder for bonding. The total thickness of the stacked powder after stacking and compaction is 200µm, and then preheating is performed at 550℃ for 2min. Then, hot rolling and cold rolling are performed alternately and cumulatively. The total rolling reduction is 50%. The rolling is performed 5 times. The first hot rolling reduction of the cumulative rolling is 25%, and then it is immediately cooled with liquid nitrogen for 6h. After taking out, the second cold rolling is immediately performed with a reduction of 25% to form an Al-Si-Mg structure composite plate.

[0061] Comparative Example 2

[0062] The element composition of the prepared composite plate is Si 4.0%, Mg 0.4%, Zr 0.5%, and the rest is Al.

[0063] (1) Calculate the required amounts of Si, Mg, and Zr according to the ratio, place the prepared pure Al in a graphite crucible of a crucible resistance furnace, heat it to 760°C and melt it, then add pure Si, pure Mg, and Al-Zr master alloy in sequence, stir and melt them at 760°C, and then keep them at 760°C for 40 minutes to prepare an Al-Si-Mg-Zr alloy melt, which is then cast into a mold at 220°C to obtain an Al-Si-Mg-Zr ingot;

[0064] (2) The Al-Si-Mg-Zr ingot was homogenized at 520°C for 2 h, furnace cooled for 24 h and then air cooled, then solution treated at 530°C for 1 h, and then aged at 240°C for 15 h to obtain Al-Si-Mg-Zr alloy samples. The Al-Si-Mg-Zr alloy samples were cut to a width ratio of 6:5, a length ratio and a thickness ratio of 1:1, and then placed in liquid nitrogen for deep cryogenic treatment for 8 h and then cold rolled. The cold rolling reduction was 90% and the rolling passes were 7 times to obtain Al-Si-Mg-Zr rolled sample plates. The thickness of the Al-Si-Mg-Zr rolled sample plates was 1.5 mm.

[0065] (3) The Al-Si-Mg-Zr rolled sample plate is pre-treated by removing edge cracks, surface cleaning, polishing and grinding, and then the three layers of Al-Si-Mg-Zr rolled sample plates are bonded together. A mold that matches the size of the middle layer Al-Si-Mg-Zr rolled sample plate is placed on the lower layer Al-Si-Mg-Zr rolled sample plate, and three layers of ultra-fine Al powder with a particle size of 1µm and three layers of medium Al powder with a particle size of 40µm are alternately stacked through a screen. The powder is compacted, and the middle layer Al-Si-Mg-Zr rolled sample plate is placed in the mold and bonded together. Three layers of ultra-fine Al powder with a particle size of 1µm and three layers of medium Al powder with a particle size of 40µm are alternately stacked through a screen. Three layers of medium Al powder with a particle size of 40µm are prepared. The powder is compacted and removed from the mold. The upper layer of Al-Si-Mg-Zr rolled sample plate is then placed on the compacted Al powder for bonding. The total thickness of the stacked powder after stacking and compaction is 200µm. It is then preheated at 550°C for 2 minutes. Subsequently, hot rolling and cold rolling are performed alternately for cumulative lamination welding. The total lamination reduction is 50%. Lamination is performed 5 times. The first pass of cumulative lamination has a hot rolling reduction of 25%, and then it is immediately cooled with liquid nitrogen for 6 hours. After being taken out, the second pass of cold rolling is immediately performed with a reduction of 25% to form a composite plate with an Al-Si-Mg-Zr structure.

[0066] Comparative Example 3

[0067] In step (2), no solution treatment and aging treatment are performed, and the remaining operations are the same as in Example 1.

[0068] Comparative Example 4

[0069] In step (3), powder stacking is not performed, and the remaining operations are the same as those in Example 1.

[0070] Comparative Example 5

[0071] In step (3), the powder is stacked to form 6 layers of ultrafine Al powder with a particle size of 1 μm in the interlayer, and the remaining operations are the same as those in Example 1.

[0072] Comparative Example 6

[0073] In step (3), the powder is stacked by piling 6 layers of medium Al powder with a particle size of 40 μm in the interlayer, and the remaining operations are the same as in Example 1.

[0074] The performance tests were conducted on the aluminum alloy composite plates prepared in Examples 1-4 and Comparative Examples 1-6, wherein:

[0075] (1) The reference standard for ultimate tensile strength and elongation at room temperature is the National Standard of the People’s Republic of China “Methods of Tensile Test of Metallic Materials at Room Temperature” (GB / T 228.1-2010);

[0076] (2) Thermal conductivity measurements follow the international standard ISO 18566-2010 "Thermal conductivity measurement method";

[0077] (3) The microhardness test was performed using a Vickers hardness tester, and 15 points of each sample were measured and the average value was taken. (4)

[0079]

[0080] From Table 1 in combination with Examples 1-4 and Comparative Examples 1-6, it can be seen that the present invention uses two types of rolled sample plates to roll aluminum alloy composite plates, which can not only achieve grain refinement, but also improve material strength and plasticity at the same time. Although Comparative Example 1-2 has higher tensile strength and Vickers hardness, its elongation is poorer than that of Example 1, and cannot meet the characteristics of high strength and toughness. Moreover, the different grain sizes and widths of plates produced when different alloy materials are rolled can assist in the bonding of the plates during cumulative rolling. The powder stacking and hot rolling combination before rolling are conducive to the close bonding of the interface. The resulting bimodal structure of fibrous coarse grains and ultrafine grains can further improve the strength and toughness of the material. The alternating combination of hot and cold rolling during rolling further refines the grains and second phase size of the plate. The combination of dissimilar materials achieves complementary properties and has a more obvious advantage of high alloy element addition compared to rolling of the same material. The gradient-layered-bimodal Al-Si-Mg / Al-Zr / Al-Si-Mg composite structure obtained by rolling has better comprehensive mechanical properties, with a tensile strength ≥335MPa, an elongation ≥24%, and a hardness ≥88HV.

Claims

1. A method for preparing an aluminum alloy composite plate, characterized in that: The following steps are involved: (1) Pure Al, pure Si and pure Mg are stirred and melted, and then kept warm and allowed to stand to prepare an Al-Si-Mg alloy melt. Pure Al and an Al-Zr master alloy are stirred and melted, and then kept warm and allowed to stand to prepare an Al-Zr alloy melt. Subsequently, they are cast to obtain Al-Si-Mg ingots and Al-Zr ingots respectively. (2) The Al-Si-Mg ingots and Al-Zr ingots were homogenized, and then solution treated and aging treated to obtain Al-Si-Mg alloy specimens and Al-Zr alloy specimens, respectively. The Al-Si-Mg alloy specimens and Al-Zr alloy specimens were cut, and then cryogenically treated and cold rolled to obtain Al-Si-Mg rolled specimen plates and Al-Zr rolled specimen plates, respectively. (3) Pre-treating the Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate, performing powder stacking between the layers of the pre-treated Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate, and then laminating, preheating and cumulative roll-bonding welding to obtain an aluminum alloy composite plate; The pretreatment in step (3) includes removing edge cracks, surface cleaning, polishing and grinding; In step (3), the powder stacking is to alternately and evenly stack the ultrafine Al powder with a particle size of 1-2µm and the medium Al powder with a particle size of 40-60µm between the layers of adjacent Al-Si-Mg rolled sample plates and Al-Zr rolled sample plates and compact them. The total thickness of the stacked powder after stacking and compaction is 200-500µm. The bonding is to place the Al-Zr rolled sample plate between two layers of Al-Si-Mg rolled sample plates. The preheating temperature is 545-555°C and the preheating time is 1-2min.

2. The method for preparing the aluminum alloy composite plate according to claim 1, wherein: In step (1), the smelting temperature is 750-790°C, the casting temperature is 220-250°C, the holding temperature is 750-790°C, and the holding time is 20-40 minutes.

3. The method for preparing the aluminum alloy composite plate according to claim 1, wherein: In step (2), the temperature for homogenization treatment is 515-525°C, the time for homogenization treatment is 1.9-2.1h, the temperature for solution treatment is 525-535°C, the time for solution treatment is 0.9-1.1h; the temperature for aging treatment is 238-242°C, the time for aging treatment is 15.8-16.2h.

4. The method for preparing the aluminum alloy composite plate according to claim 1, wherein: In step (2), the Al-Si-Mg alloy sample and the Al-Zr alloy sample are cut to a width ratio of 5-8:3-6, a length ratio of 1:1-1.5, and a thickness ratio of 1:1-1.

5.

5. The method for preparing the aluminum alloy composite plate according to claim 1, wherein: In step (2), the medium for cryogenic treatment is liquid nitrogen, the time for cryogenic treatment is 4-10 h, the reduction of cold rolling is 84-95%, the number of cold rolling passes is 5-8 times, and the thickness of the Al-Si-Mg rolled sample plate and the Al-Zr rolled sample plate are both 1.3-1.7 mm.

6. The method for preparing the aluminum alloy composite plate according to claim 1, wherein: The mass percentages of the elements in the aluminum alloy composite plate in step (3) are Si: 4.0-5.0%, Mg: 0.2-0.8%, Zr: 0.2-1.0%, and the rest is Al.

7. The method for preparing the aluminum alloy composite plate according to claim 1, wherein: In step (3), the cumulative roll-to-roll welding is performed by alternating hot rolling and cold rolling, the total roll-to-roll reduction is 50-90%, and the number of roll-to-rolling is 3-6 times.

8. The method for preparing the aluminum alloy composite plate according to claim 7, wherein: The rolling passes are two times during the stack rolling, the first pass is hot rolling and the second pass is cold rolling; the stack rolling is performed by liquid nitrogen cooling for 4-10 hours immediately after hot rolling, and cold rolling is performed immediately after taking out.

Images