Aluminum alloy clad sheet and method of making

Abstract

This invention relates to the field of aluminum alloy processing and manufacturing technology, specifically to an aluminum alloy composite plate and strip and its preparation method. The aluminum alloy composite plate and strip consists of an upper brazing layer, an intermediate substrate layer, and a lower brazing layer connected in sequence. The upper and lower brazing layers are made of 4-series aluminum alloys, and the intermediate substrate layer is made of 6-series aluminum alloys. The mass ratio of Si in the upper brazing layer to Si in the intermediate substrate layer is 6-12:1, and the mass ratio of Si in the lower brazing layer to Si in the intermediate substrate layer is also 6-12:1. This aluminum alloy composite plate and strip possesses excellent strength, plasticity, and heat resistance.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy processing and manufacturing technology, specifically to an aluminum alloy composite plate and strip and its preparation method. Background Technology

[0002] According to GB / T 33369-2016: Aluminum Alloy Composite Plates, Strips, and Foils for Brazing, the following problems exist in the existing system of aluminum alloy composite plates and strips for brazing: 1. High-strength aluminum alloy composite plates and strips for brazing have very poor plasticity (tensile strength: 115~225 MPa, yield strength ≥125 MPa, elongation: 0.5~5.0%), and the high-strength aluminum alloy composite plates and strips for brazing also have poor heat resistance, resulting in significant strength loss at higher temperatures, thus greatly limiting their application; 2. High-plasticity brazing aluminum alloy composite plates and strips have relatively low mechanical properties (tensile strength: 90~160Mpa, yield strength ≥35MPa, elongation: 6.0~25%). 3. Due to the huge differences in chemical composition between the brazing layer (4-series aluminum alloy, high Si content) and the base material (3-series, 6-series, and 7-series aluminum alloy), scrapped brazing composite plates and strips cannot be separated or directly recycled (100% directly used as raw materials), posing a great challenge to recycling.

[0003] In summary, there is an urgent need for an aluminum alloy sheet and strip that combines mechanical properties, plasticity, and tensile strength after baking, and is easy to recycle without requiring additional chemical composition adjustments. Summary of the Invention

[0004] The present invention aims to solve the technical problem of how to provide an aluminum alloy sheet and strip material that combines strength, plasticity and heat resistance.

[0005] To achieve the above objectives, the first aspect of the present invention provides an aluminum alloy composite plate and strip, wherein the aluminum alloy composite plate and strip is composed of an upper brazing layer, an intermediate substrate layer and a lower brazing layer connected in sequence.

[0006] The upper and lower brazing layers are made of 4-series aluminum alloy;

[0007] The components and their weight percentages in the upper and lower brazing layers are as follows:

[0008] The Si content is 6.3-15.3%;

[0009] The Fe content is 0.1-0.3%;

[0010] Cu content ≤ 0.03%;

[0011] Mn content ≤ 0.03%;

[0012] Mg content ≤ 0.02%;

[0013] Cr content ≤0.03%;

[0014] Ni content ≤ 0.03%;

[0015] Zn content ≤ 0.02%;

[0016] The Ti content is 0.01-0.03%;

[0017] The content of other impurity elements is ≤0.05%;

[0018] The total content of other impurity elements is ≤0.15%;

[0019] The balance is Al;

[0020] The intermediate substrate layer is a 6-series aluminum alloy;

[0021] The components and their weight percentages in the intermediate substrate layer are as follows:

[0022] The Si content is 0.7-1.7%;

[0023] The Fe content is 0.2-0.6%;

[0024] Cu content ≤ 0.03%;

[0025] Mn content ≤ 0.03%;

[0026] The Mg content is 0.4-1.2%;

[0027] Cr content ≤0.03%;

[0028] Ni content ≤ 0.03%;

[0029] Zn content ≤ 0.02%;

[0030] The Ti content is 0.01-0.03%;

[0031] The content of other impurity elements is ≤0.05%;

[0032] The total content of other impurity elements is ≤0.15%;

[0033] The balance is Al;

[0034] The mass ratio of Si in the upper brazing layer to Si in the intermediate substrate layer is 6-12:1;

[0035] The mass ratio of Si in the lower brazing layer to Si in the intermediate substrate layer is 6-12:1.

[0036] A second aspect of the present invention provides a method for preparing the above-mentioned aluminum alloy composite plate and strip, wherein the preparation method includes the following steps:

[0037] The cast upper and lower brazing layers are heated, hot rolled for the first time, and welded to the intermediate base material layer. Then, they are hot rolled for the second time, cold rolled, solution quenched, stretched, aged, re-rolled and sheared, and packaged.

[0038] The heating conditions include: the metal temperature of the upper and lower brazing layers is 480-520℃, and the temperature is maintained for 2-6 hours;

[0039] The conditions for the first hot rolling include: the first hot roughing rolling passes are 15-19, the theoretical design coverage b is 5-15%, and the relationship between the theoretical design coverage b, the thickness H of the intermediate substrate layer, and the total thickness h of the upper and lower brazing layers satisfies: b%=h / (2h+H)×100%, the unit of the thickness H of the intermediate substrate layer is mm, and the unit of the total thickness h of the upper and lower brazing layers is mm.

[0040] The beneficial effects of this invention are as follows:

[0041] This invention uses a composite of 4-series aluminum alloy, 6-series aluminum alloy, and 4-series aluminum alloy to produce brazing aluminum alloy strips. This allows the traditional 4-series aluminum alloy, which cannot be strengthened by heat treatment, and the 6-series aluminum alloy, which can be strengthened by heat treatment, to complement each other. The resulting aluminum alloy strips have excellent strength, plasticity, and tensile strength after baking. The waste is easy to recycle and has good application prospects. Detailed Implementation

[0042] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0043] In the existing technology, 4-series aluminum alloys are non-heat-treatable strengthening alloys, with low strength and good plasticity in the annealed state; while the strength increases when cold-worked, the plasticity decreases rapidly. 6-series aluminum alloys, on the other hand, are heat-treatable strengthening alloys with medium to high strength. After heat treatment, both strength and plasticity can be improved. However, simply combining the two aluminum alloys is not enough to make the aluminum alloy composite plate and strip have both excellent strength and plasticity.

[0044] In this invention, the inventors discovered that by controlling the alloy composition and adjusting the processing technology, aluminum alloy composite plates and strips can possess both excellent strength and plasticity.

[0045] To achieve this goal, the inventors attempted to optimize the composition and processing technology of each component of the aluminum alloy composite plate and strip. The inventors discovered that the above-mentioned objective can be achieved through specific component composition and heating and welding processes. Furthermore, specific rolling, solution treatment and aging processes make the performance of the aluminum alloy composite plate and strip even better.

[0046] The first aspect of the present invention provides an aluminum alloy composite plate and strip, wherein the aluminum alloy composite plate and strip is composed of an upper brazing layer, an intermediate substrate layer and a lower brazing layer connected in sequence;

[0047] The upper and lower brazing layers are made of 4-series aluminum alloy;

[0048] The components and their weight percentages in the upper and lower brazing layers are as follows:

[0049] The Si content is 6.3-15.3%;

[0050] The Fe content is 0.1-0.3%;

[0051] Cu content ≤ 0.03%;

[0052] Mn content ≤ 0.03%;

[0053] Mg content ≤ 0.02%;

[0054] Cr content ≤0.03%;

[0055] Ni content ≤ 0.03%;

[0056] Zn content ≤ 0.02%;

[0057] The Ti content is 0.01-0.03%;

[0058] The content of other impurity elements is ≤0.05%;

[0059] The total content of other impurity elements is ≤0.15%;

[0060] The balance is Al;

[0061] The intermediate substrate layer is a 6-series aluminum alloy;

[0062] The components and their weight percentages in the intermediate substrate layer are as follows:

[0063] The Si content is 0.7-1.7%;

[0064] The Fe content is 0.2-0.6%;

[0065] Cu content ≤ 0.03%;

[0066] Mn content ≤ 0.03%;

[0067] The Mg content is 0.4-1.2%;

[0068] Cr content ≤0.03%;

[0069] Ni content ≤ 0.03%;

[0070] Zn content ≤ 0.02%;

[0071] The Ti content is 0.01-0.03%;

[0072] The content of other impurity elements is ≤0.05%;

[0073] The total content of other impurity elements is ≤0.15%;

[0074] The balance is Al;

[0075] The mass ratio of Si in the upper brazing layer to Si in the intermediate substrate layer is 6-12:1;

[0076] The mass ratio of Si in the lower brazing layer to Si in the intermediate substrate layer is 6-12:1.

[0077] In this invention, both the upper and lower brazing layers of the aluminum alloy composite plate and strip are made of 4-series aluminum alloy. The main alloying element in the aluminum alloy is Si, and the main impurity element is Fe. By changing the Fe element from an impurity element to an alloying element and controlling the Fe element content in the aluminum alloy to 0.1-0.3%, the FeAl3 phase and AlFeSi phase are mainly formed. This ensures that the upper and lower brazing layers have a certain strength and also appropriately improves the heat resistance of the plate and strip.

[0078] The intermediate substrate layer of the composite plate and strip of the present invention is made of 6-series aluminum alloy, and the Fe element content is controlled at 0.2-0.6%. This not only has the effect of refining recrystallized grains, but also the strength of the upper and lower brazing materials and the intermediate substrate layer in the hot-rolled state is mainly determined by Fe and Si elements. Similar strengths facilitate rolling composite.

[0079] According to the present invention, the thickness ratio of the upper brazing layer, the intermediate substrate layer and the lower brazing layer is 1:8-12:1.

[0080] According to the present invention, the tensile strength of the aluminum alloy composite plate and strip is 205-359 MPa, the specified non-proportional elongation strength is 183-316 MPa, the elongation after fracture is 11.9-14.5%, and the ratio of the tensile strength after baking to the original tensile strength is ≥95%.

[0081] In this invention, the method for testing the tensile strength after baking is to bake the aluminum alloy composite plate strip at 230 ℃ for 1 h, and then test the tensile strength after cooling.

[0082] A second aspect of the present invention provides a method for preparing the above-mentioned aluminum alloy composite plate and strip, wherein the preparation method includes the following steps:

[0083] The cast upper and lower brazing layers are heated, hot rolled for the first time, and welded to the intermediate base material layer. Then, they are hot rolled for the second time, cold rolled, solution quenched, stretched, aged, re-rolled and sheared, and packaged.

[0084] The heating conditions include: the metal temperature of the upper and lower brazing layers is 480-520℃, and the temperature is maintained for 2-6 hours;

[0085] The conditions for the first hot rolling include: the first hot roughing rolling passes are 15-19, the theoretical design coverage b is 5-15%, and the relationship between the theoretical design coverage b, the thickness H of the intermediate substrate layer, and the total thickness h of the upper and lower brazing layers satisfies: b%=h / (2h+H)×100%, the unit of the thickness H of the intermediate substrate layer is mm, and the unit of the total thickness h of the upper and lower brazing layers is mm.

[0086] In this invention, the theoretical design coverage b is designed to be 5-15%, and the mass ratio of Si element in the upper and lower brazing layers to the intermediate substrate layer is 6-12:1. The chemical composition of 6-series aluminum alloy is compatible with 4-series aluminum alloy, which solves the problem of difficult recycling of composite strips, saves raw materials, and helps reduce production costs. The aluminum alloy composite plate and strip prepared by the preparation method provided by this invention has both strength, plasticity and heat resistance, which can solve the problem of contradiction between strength and plasticity and insufficient heat resistance of existing aluminum alloy brazing materials.

[0087] The aluminum alloy ingots prepared by this invention have a low degree of alloying, eliminating the need for long-term high-temperature homogenization heating of the ingots, thus saving energy consumption and reducing production costs.

[0088] In this invention, the upper and lower brazing layers are made of 4-series aluminum alloy and are prepared using conventional 4-series aluminum alloy preparation methods in the art.

[0089] In this invention, the intermediate substrate layer is a 6-series aluminum alloy, which is prepared using conventional 6-series aluminum alloy preparation methods in the art.

[0090] According to some preferred embodiments of the present invention, the preparation method of the upper brazing layer and the lower brazing layer includes: batching, smelting, refining, casting, milling, heating, and hot rolling;

[0091] The preparation method of the intermediate substrate layer includes: batching, smelting, refining, casting, and milling;

[0092] According to the present invention, in the preparation of the upper brazing layer and the lower brazing layer, the upper brazing layer and the lower brazing layer after sawing and milling need to be heated and then hot rolled to a thickness h, and then composited with the intermediate substrate layer of thickness H after sawing and milling.

[0093] The melting conditions for the upper and lower brazing layers include: sequentially adding the ingredients into the melting furnace for melting at a temperature of 700-760℃ for 4-10 hours, and using flux for the first refining and covering process. After the materials in the furnace have melted after feeding, stirring is started, followed by a second refining process. The conditions for the second refining of the upper and lower brazing layers include: a refining temperature of 720-750℃ for 0.5-4 hours, and slag removal.

[0094] According to the present invention, after slag removal, nitrogen (N2) is used to carry hydrogen and fine impurities in the molten aluminum to the surface of the melt, thereby reducing the gas content of the melt and meeting the requirement of not less than level 2 as specified in GB / T 32186-2015 Test Method for Purity of Aluminum and Aluminum Alloy Ingots.

[0095] According to the present invention, the casting speed is 40-60 m / min, and a two-stage filtration is used during the casting process. The two-stage filtration can be any one of plate CFF filtration + plate CFF filtration, plate CFF filtration + deep bed filtration, or plate CFF filtration + tubular filtration, thereby reducing the slag content of the melt, ensuring the purity of the melt, and meeting the requirement of not less than level 2 as specified in GB / T 32186-2015 Test Method for Purity of Aluminum and Aluminum Alloy Ingots. Al-5Ti-B is used for online refining treatment to ensure the grain size of the aluminum alloy ingot.

[0096] According to the present invention, an integrated air-cushion continuous solution quenching method is used, in which cleaning, solution treatment and quenching are completed simultaneously, the strip does not come into contact with the heat treatment furnace, and the surface quality of the strip is excellent.

[0097] According to the present invention, the sheet and strip materials that have undergone the aging process can be rewound and rolled into strip materials by a rewinding machine after edge trimming and shearing, or they can be sheared and flattened into sheet materials by cross-cutting.

[0098] According to the present invention, the welding conditions include: bonding the ingot in the order of upper brazing layer, intermediate substrate layer and lower brazing layer, using argon-shielded welding, spot welding, with a weld length of 20-30mm and a center-to-center distance of 60-80mm, drilling holes on the inner side of the ingot 20-30mm away from the center of the weld, fixing with aluminum alloy rivets to obtain a composite ingot, and then heating the composite ingot to a metal temperature of 480-520℃ and holding for 2-6 hours.

[0099] According to the present invention, the conditions for the second hot rolling include: performing a second hot rough rolling on the heat-insulated composite material, then performing a third hot rough rolling, then performing a hot finish rolling, and cooling to 20-30°C;

[0100] The second hot roughing is a dry rolling process without emulsion spraying. The second hot roughing has 6-8 passes and a reduction rate of 3-5%.

[0101] The third hot roughing mill has 15-19 passes, a reduction rate of 10-25%, and a rolling speed of 2-2.5 m / s. The reduction rate of the third hot roughing mill increases uniformly from 10% to 25% with the increase of the number of passes, and the rolling speed of the third hot roughing mill increases uniformly from 2 m / s to 2.5 m / s with the increase of the number of passes.

[0102] The thickness of the intermediate slab after the third hot roughing is 35-45mm, the final rolling temperature of the third hot roughing is 370-410℃, the hot finishing four-roller is used for coiling and trimming, the final rolling temperature of the hot finishing is 300-320℃, and the thickness of the strip after hot finishing is 2.5-8mm.

[0103] In this invention, after dry rolling, the upper brazing layer, the intermediate substrate layer and the lower brazing layer are physically composited, and the composite interface is firmly bonded. By uniformly increasing the reduction rate and the rolling speed according to the specific method of this invention, the rolling force increases, the material deformation is greater and more complete, and the composite interface is more tightly bonded, realizing atomic-level micro-composite bonding and giving full play to the synergistic effect of the two materials.

[0104] According to the present invention, the conditions for cold rolling include: the thickness of the strip after cold rolling is 0.5-4 mm, and the total processing rate of cold rolling is 50-80%.

[0105] In this invention, the total processing rate of cold rolling is ((hot-rolled thickness - final cold-rolled thickness) ÷ hot-rolled thickness) × 100%.

[0106] In this invention, cold rolling is used in 1-2 passes, with a total cold rolling processing rate of 50-80%. The high processing rate is beneficial for breaking down the microstructure. Through subsequent rapid and short-term solution treatment, the recrystallization structure of the upper and lower brazing layers of the 4-series aluminum alloy on the surface is guaranteed, and the solution treatment of the fully rolled intermediate substrate layer is also beneficial. However, excessive processing rate will increase production costs.

[0107] According to the present invention, the conditions for solution quenching include: a solution temperature of 510-570℃, a solution time of 10-100s, and water cooling to 20-30℃ after solution treatment.

[0108] According to the present invention, the stretching conditions include: stretching and straightening the solution-treated and water-cooled strip material, with a stretching rate of 0-0.5%.

[0109] According to the present invention, the aging conditions include: the temperature of the sheet / strip is 155-175°C, the holding time is 4-20h, after holding, it is cooled to 150°C at a rate of 10-20°C / h, and then naturally cooled to 20-30°C.

[0110] In this invention, specific aging causes the supersaturated solid solution to decompose, and alloying elements precipitate from the matrix. Different degrees of precipitation can produce different combinations of strength and plasticity. Peak aging has the highest strength and reduces plasticity. Compared with peak aging, under-aging can increase strength and reduce plasticity less. Natural aging has the lowest strength and the best plasticity.

[0111] Test methods

[0112] Tensile strength, specified non-proportional elongation strength, and elongation after fracture shall be in accordance with GB / T 16865-2023 Specimens and methods for tensile testing of wrought aluminum, magnesium and their alloy processed products.

[0113] The heat resistance performance was determined at 230℃ for 1 hour. The tensile strength was tested according to GB / T 16865-2023 "Specimens and Methods for Tensile Testing of Deformed Aluminum, Magnesium and Their Alloys" and the ratio to the original tensile strength was calculated.

[0114] The technical solution of the present invention will be further described in detail below with reference to the embodiments. Obviously, the embodiments described herein are only some embodiments of the present invention and are not intended to limit the present invention. All other embodiments implemented by those skilled in the art based on the embodiments of the present invention without creative improvements are within the protection scope of the present invention.

[0115] Example 1

[0116] The upper brazing layer, the intermediate substrate layer, and the lower brazing layer are prepared using conventional manufacturing methods in the art.

[0117] The components and their weight percentages in the upper and lower brazing layers are as follows:

[0118] The Si content is 10.8%; the Fe content is 0.2%; the Cu content is ≤0.03%; the Mn content is ≤0.03%; the Mg content is ≤0.02%; the Cr content is ≤0.03%; the Ni content is ≤0.03%; the Zn content is ≤0.02%; and the Ti content is 0.02%.

[0119] The content of each other impurity element is ≤0.05%; the total content of other impurity elements is ≤0.15%; the balance is Al.

[0120] The components and their weight percentages in the intermediate substrate layer are as follows:

[0121] The content of Si is 1.0%; the content of Fe is 0.4%; the content of Cu is ≤0.03%; the content of Mn is ≤0.03%; the content of Mg is 0.8%; the content of Cr is ≤0.03%; the content of Ni is ≤0.03%; the content of Zn is ≤0.02%; the content of Ti is 0.02%; the content of other impurity elements is ≤0.05% for each individual element; the total content of other impurity elements is ≤0.15%; and the balance is Al.

[0122] The cast upper and lower brazed layers are heated, hot-rolled for the first time, and welded to the intermediate substrate layer. Then, they are hot-rolled again, cold-rolled, solution-quenched, stretched, aged, re-rolled, cross-slit, and packaged.

[0123] The heating conditions include: the metal temperature of the upper and lower brazing layers is 500℃, and the temperature is maintained for 4 hours;

[0124] The conditions for the first hot rolling include: the first hot roughing rolling passes are 6 passes, the theoretical design coverage b is 10%, the theoretical design coverage b, the thickness H of the intermediate substrate layer is 400mm, and the total thickness h of the upper and lower brazing layers is 100mm. The relationship satisfies: b%=h / (2h+H)×100%.

[0125] The welding conditions include: bonding the ingots in the order of upper brazing layer, middle substrate layer and lower brazing layer, using argon shielded welding, spot welding, with a weld length of 25mm and a center-to-center distance of 70mm between welds, drilling holes on the inside of the ingot 25mm from the center of the weld, and fixing it with aluminum alloy rivets to obtain a composite ingot, and then heating the composite ingot to a metal temperature of 500℃ and holding it at that temperature for 4 hours.

[0126] The conditions for the second hot rolling include: performing a second hot roughing roll on the heat-insulated composite material, followed by a third hot roughing roll, then a hot finishing roll, and cooling to 25°C.

[0127] The second hot roughing roll is a dry roll without emulsion spraying. The second hot roughing roll has 17 passes and a reduction rate of 4%.

[0128] The third hot roughing mill has 17 passes, a reduction rate of 18%, and a rolling speed of 2.3 m / s. The reduction rate of the third hot roughing mill increases uniformly from 10% to 25% with the increase of the number of passes, and the rolling speed of the third hot roughing mill increases uniformly from 2 m / s to 2.5 m / s with the increase of the number of passes.

[0129] The thickness of the intermediate slab after the third hot roughing is 40 mm, the final rolling temperature of the third hot roughing is 390℃, the edge is cut by four consecutive hot finishing rolling, the final rolling temperature of the hot finishing is 310℃, and the thickness of the strip after hot finishing is 5 mm.

[0130] The conditions for cold rolling include: the strip thickness after cold rolling is 1.7 mm, and the total processing rate of cold rolling is 66%.

[0131] The conditions for solution quenching include: solution temperature of 540℃, solution time of 55s, and water cooling to 25℃ after solution treatment.

[0132] The stretching conditions include: stretching and straightening the solution-treated and water-cooled strip and sheet material, with a stretching rate of 0.2%.

[0133] The aging conditions include: the temperature of the sheet / strip is 165℃, the holding time is 12h, after holding, it is cooled to 150℃ at a rate of 15℃ / h, and then naturally cooled to 25℃.

[0134] An aluminum alloy composite strip A1 is prepared, wherein the mass ratio of Si in the upper brazing layer to Si in the intermediate substrate layer is 9:1, the mass ratio of Si in the lower brazing layer to Si in the intermediate substrate layer is 9:1, and the thickness ratio of the upper brazing layer, the intermediate substrate layer, and the lower brazing layer is 1:11:1.

[0135] The composite aluminum alloy sheet and strip of the present invention, from the precise design stage, takes into account 100% recycling and preservation. Process waste, geometric waste and scrap products generated in each process of production and scrap products after use can all be used as base material without additional adjustments.

[0136] Example 2

[0137] The upper brazing layer, the intermediate substrate layer, and the lower brazing layer are prepared using conventional manufacturing methods in the art.

[0138] The components and their weight percentages in the upper and lower brazing layers are as follows:

[0139] The Si content is 6.3%; the Fe content is 0.1%; the Cu content is ≤0.03%; the Mn content is ≤0.03%; the Mg content is ≤0.02%; the Cr content is ≤0.03%; the Ni content is ≤0.03%; the Zn content is ≤0.02%; and the Ti content is 0.01%.

[0140] The content of each other impurity element is ≤0.05%; the total content of other impurity elements is ≤0.15%; the balance is Al.

[0141] The components and their weight percentages in the intermediate substrate layer are as follows:

[0142] The content of Si is 0.7%; the content of Fe is 0.3%; the content of Cu is ≤0.03%; the content of Mn is ≤0.03%; the content of Mg is 0.4%; the content of Cr is ≤0.03%; the content of Ni is ≤0.03%; the content of Zn is ≤0.02%; the content of Ti is 0.01%; the content of other impurity elements is ≤0.05% for each individual element; the total content of other impurity elements is ≤0.15%; and the balance is Al.

[0143] The cast upper and lower brazed layers are heated, hot-rolled for the first time, and welded to the intermediate substrate layer. Then, they are hot-rolled again, cold-rolled, solution-quenched, stretched, aged, re-rolled, cross-slit, and packaged.

[0144] The heating conditions include: the metal temperature of the upper and lower brazing layers is 480℃, and the temperature is maintained for 2 hours;

[0145] The conditions for the first hot rolling include: 15 passes for the first hot roughing, a theoretical design coverage rate b of 5%, a theoretical design coverage rate b, an intermediate substrate layer thickness H of 500 mm, and a total thickness h of the upper and lower brazing layers of 55.6 mm. The relationship satisfies: b%=h / (2h+H)×100%.

[0146] The welding conditions include: bonding the ingots in the order of upper brazing layer, middle substrate layer and lower brazing layer, using argon shielded welding, spot welding, with a weld length of 20mm and a center-to-center distance of 60mm between welds, drilling holes on the inside of the ingot 20mm from the center of the weld, and fixing it with aluminum alloy rivets to obtain a composite ingot, and then heating the composite ingot to a metal temperature of 480℃ and holding it at that temperature for 2 hours.

[0147] The conditions for the second hot rolling include: performing a second hot roughing roll on the heat-insulated composite material, followed by a third hot roughing roll, then a hot finishing roll, and cooling to 20°C.

[0148] The second hot roughing roll is a dry roll without emulsion spraying. The second hot roughing roll consists of 6 passes and has a reduction rate of 3%.

[0149] The third hot roughing mill has 15 passes, a reduction rate of 10%, and a rolling speed of 2 m / s. The reduction rate of the third hot roughing mill increases uniformly from 10% to 25% with the increase of the number of passes, and the rolling speed of the third hot roughing mill increases uniformly from 2 m / s to 2.5 m / s with the increase of the number of passes.

[0150] The thickness of the intermediate slab after the third hot roughing is 35mm, the final rolling temperature of the third hot roughing is 370℃, the edge is cut by four consecutive hot finishing rolling, the final rolling temperature of the hot finishing is 300℃, and the thickness of the strip after hot finishing is 2.5mm.

[0151] The conditions for cold rolling include: the thickness of the strip after cold rolling is 0.5 mm, and the total processing rate of cold rolling is 80%.

[0152] The conditions for solution quenching include: solution temperature of 510℃, solution time of 10s, and water cooling to 20℃ after solution treatment.

[0153] The stretching conditions include: stretching and straightening the solution-treated and water-cooled strip and sheet material, with a stretching rate of 0%.

[0154] The aging conditions include: the temperature of the sheet / strip is 155℃, the holding time is 4h, after holding is cooled to 150℃ at a rate of 10℃ / h, and then naturally cooled to 20℃.

[0155] An aluminum alloy composite strip A2 is prepared, wherein the mass ratio of Si in the upper brazing layer to Si in the intermediate substrate layer is 6:1, the mass ratio of Si in the lower brazing layer to Si in the intermediate substrate layer is 6:1, and the thickness ratio of the upper brazing layer, the intermediate substrate layer, and the lower brazing layer is 1:8:1.

[0156] Example 3

[0157] The upper brazing layer, the intermediate substrate layer, and the lower brazing layer are prepared using conventional manufacturing methods in the art.

[0158] The components and their weight percentages in the upper and lower brazing layers are as follows:

[0159] The Si content is 15.3%; the Fe content is 0.3%; the Cu content is ≤0.03%; the Mn content is ≤0.03%; the Mg content is ≤0.02%; the Cr content is ≤0.03%; the Ni content is ≤0.03%; the Zn content is ≤0.02%; and the Ti content is 0.03%.

[0160] The content of each other impurity element is ≤0.05%; the total content of other impurity elements is ≤0.15%; the balance is Al.

[0161] The components and their weight percentages in the intermediate substrate layer are as follows:

[0162] The content of Si is 1.7%; the content of Fe is 0.6%; the content of Cu is ≤0.03%; the content of Mn is ≤0.03%; the content of Mg is 1.2%; the content of Cr is ≤0.03%; the content of Ni is ≤0.03%; the content of Zn is ≤0.02%; the content of Ti is 0.03%; the content of other impurity elements is ≤0.05% for each individual element; the total content of other impurity elements is ≤0.15%; and the balance is Al.

[0163] The cast upper and lower brazed layers are heated, hot-rolled for the first time, and welded to the intermediate substrate layer. Then, they are hot-rolled again, cold-rolled, solution-quenched, stretched, aged, re-rolled, cross-slit, and packaged.

[0164] The heating conditions include: the metal temperature of the upper and lower brazing layers is 520℃, and the holding time is 6 hours;

[0165] The conditions for the first hot rolling include: 19 passes for the first hot roughing, a theoretical design coverage rate b of 15%, a theoretical design coverage rate b, an intermediate substrate layer thickness H of 500 mm, and a total thickness h of the upper and lower brazing layers of 214.3 mm. The relationship satisfies: b%=h / (2h+H)×100%.

[0166] The welding conditions include: bonding the ingots in the order of upper brazing layer, middle substrate layer and lower brazing layer, using argon shielded welding, spot welding with a weld length of 30mm and a center-to-center distance of 80mm, drilling holes on the inside of the ingot 30mm from the center of the weld, and fixing it with aluminum alloy rivets to obtain a composite ingot, and then heating the composite ingot to a metal temperature of 520℃ and holding it at that temperature for 6 hours.

[0167] The conditions for the second hot rolling include: performing a second hot roughing roll on the heat-insulated composite material, followed by a third hot roughing roll, then a hot finishing roll, and cooling to 30°C.

[0168] The second hot roughing roll is a dry roll without emulsion spraying, and it consists of 8 passes with a reduction rate of 5%.

[0169] The third hot roughing mill has 19 passes, a reduction rate of 25%, and a rolling speed of 2.5 m / s. The reduction rate of the third hot roughing mill increases uniformly from 10% to 25% with the increase of the number of passes, and the rolling speed of the third hot roughing mill increases uniformly from 2 m / s to 2.5 m / s with the increase of the number of passes.

[0170] The thickness of the intermediate slab after the third hot roughing is 45mm, the final rolling temperature of the third hot roughing is 410℃, the hot finishing four-roller is used for coiling and trimming, the final rolling temperature of the hot finishing is 320℃, and the thickness of the strip after hot finishing is 8mm.

[0171] The conditions for cold rolling include: the strip thickness after cold rolling is 4 mm, and the total processing rate of cold rolling is 50%.

[0172] The conditions for solution quenching include: a solution temperature of 570℃, a solution time of 100s, and water cooling to 30℃ after solution treatment.

[0173] The stretching conditions include: stretching and straightening the solution-treated and water-cooled strip and sheet material, with a stretching rate of 0.5%.

[0174] The aging conditions include: the temperature of the sheet / strip is 175℃, the holding time is 20h, after holding, it is cooled to 150℃ at a rate of 20℃ / h, and then naturally cooled to 30℃.

[0175] An aluminum alloy composite strip A3 is prepared, wherein the mass ratio of Si in the upper brazing layer to Si in the intermediate substrate layer is 12:1, the mass ratio of Si in the lower brazing layer to Si in the intermediate substrate layer is 12:1, and the thickness ratio of the upper brazing layer, the intermediate substrate layer, and the lower brazing layer is 1:14:1.

[0176] Comparative Example 1

[0177] Aluminum alloy composite sheet and strip were prepared according to the method of Example 1, except that the cold rolling conditions included: the strip thickness after cold rolling was 3.5 mm, and the total cold rolling rate was 30%.

[0178] Aluminum alloy composite plate and strip material DA1 was obtained.

[0179] Comparative Example 2

[0180] Aluminum alloy composite sheet and strip were prepared according to the method of Example 1, except that the cold rolling conditions included: the strip thickness after cold rolling was 0.5 mm, and the total cold rolling rate was 90%.

[0181] Aluminum alloy composite plate and strip material DA2 was obtained.

[0182] Comparative Example 3

[0183] Aluminum alloy composite sheet and strip were prepared according to the method in Example 1, except that the aging conditions included: the temperature of the sheet and strip was 130°C, the holding time was 2 hours, and the material was naturally cooled to 25°C after the holding time was completed.

[0184] Aluminum alloy composite plate and strip material DA3 was obtained.

[0185] Comparative Example 4

[0186] Aluminum alloy composite sheet and strip were prepared according to the method of Example 1, except that the aging conditions included: the temperature of the sheet and strip was 200°C, the holding time was 24h, and after holding, it was cooled to 25°C at a rate of 25°C / h, and then naturally cooled to 25°C.

[0187] Aluminum alloy composite plate and strip material DA4 was obtained.

[0188] Performance tests were performed on A1-A3 and DA1-DA4, as shown in Table 1.

[0189] Table 1

[0190]

[0191] By comparing the examples and comparative examples, it can be seen that the aluminum alloy composite plate and strip provided by the present invention has excellent strength, plasticity and tensile strength after baking.

[0192] In Comparative Example 1, the cold rolling processing rate of the strip will produce an orange peel texture on the surface, affecting the material properties. In Comparative Example 2, the cold rolling processing rate is too high, which will increase the number of passes, cause edge cracking, increase energy consumption, and reduce the product yield. Because of poor plasticity, it is difficult to sew during the production process.

[0193] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An aluminum alloy composite plate and strip, characterized in that, The aluminum alloy composite strip is composed of an upper brazing layer, an intermediate substrate layer and a lower brazing layer connected in sequence. The upper and lower brazing layers are made of 4-series aluminum alloy; The components and their weight percentages in the upper and lower brazing layers are as follows: The Si content is 6.3-15.3%; The Fe content is 0.1-0.3%; Cu content ≤ 0.03%; Mn content ≤ 0.03%; Mg content ≤ 0.02%; Cr content ≤0.03%; Ni content ≤ 0.03%; Zn content ≤ 0.02%; The Ti content is 0.01-0.03%; The content of other impurity elements is ≤0.05%; The total content of other impurity elements is ≤0.15%; The balance is Al; The intermediate substrate layer is a 6-series aluminum alloy; The components and their weight percentages in the intermediate substrate layer are as follows: The Si content is 0.7-1.7%; The Fe content is 0.2-0.6%; Cu content ≤ 0.03%; Mn content ≤ 0.03%; The Mg content is 0.4-1.2%; Cr content ≤0.03%; Ni content ≤ 0.03%; Zn content ≤ 0.02%; The Ti content is 0.01-0.03%; The content of other impurity elements is ≤0.05%; The total content of other impurity elements is ≤0.15%; The balance is Al; The mass ratio of Si in the upper brazing layer to Si in the intermediate substrate layer is 6-12:1; The mass ratio of Si in the lower brazing layer to Si in the intermediate substrate layer is 6-12:

1.

2. The aluminum alloy composite plate and strip according to claim 1, characterized in that, The thickness ratio of the upper brazing layer, the intermediate substrate layer, and the lower brazing layer is 1:6-12:

1.

3. The aluminum alloy composite plate and strip according to claim 1, characterized in that, The aluminum alloy composite sheet and strip have a tensile strength of 205-359 MPa, a specified non-proportional elongation strength of 183-316 MPa, an elongation after fracture of 11.9-14.5%, and a tensile strength after baking that is ≥95% of the original tensile strength.

4. A method for preparing the aluminum alloy composite plate / strip according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: The cast upper and lower brazing layers are heated, hot rolled for the first time, and welded to the intermediate base material layer. Then, they are hot rolled for the second time, cold rolled, solution quenched, stretched, aged, re-rolled and sheared, and packaged. The heating conditions include: the metal temperature of the upper and lower brazing layers is 480-520℃, and the temperature is maintained for 2-6 hours; The conditions for the first hot rolling include: the first hot roughing rolling passes are 15-19, the theoretical design coverage b is 5-15%, and the relationship between the theoretical design coverage b, the thickness H of the intermediate substrate layer, and the total thickness h of the upper and lower brazing layers satisfies: b%=h / (2h+H)×100%, the unit of the thickness H of the intermediate substrate layer is mm, and the unit of the total thickness h of the upper and lower brazing layers is mm.

5. The method for preparing aluminum alloy composite plate and strip according to claim 4, characterized in that, The welding conditions include: bonding the ingots in the order of upper brazing layer, intermediate substrate layer and lower brazing layer, using argon shielded welding, spot welding, with a weld length of 20~30mm and a center-to-center distance of 60~80mm, drilling holes on the inside of the ingot 20~30mm from the center of the weld, and fixing it with aluminum alloy rivets to obtain a composite ingot, and then heating the composite ingot to a metal temperature of 480-520℃ and holding it at that temperature for 2-6 hours.

6. The method for preparing aluminum alloy composite plate and strip according to claim 4, characterized in that, The conditions for the second hot rolling include: performing a second hot roughing roll on the heat-insulated composite material, followed by a third hot roughing roll, then a hot finishing roll, and cooling to 20-30°C; The second hot roughing is a dry rolling process without emulsion spraying. The second hot roughing has 6-8 passes and a reduction rate of 3-5%. The third hot roughing mill has 15-19 passes, a reduction rate of 10-25%, and a rolling speed of 2-2.5 m / s. The reduction rate of the third hot roughing mill increases uniformly from 10% to 25% with the increase of the number of passes, and the rolling speed of the third hot roughing mill increases uniformly from 2 m / s to 2.5 m / s with the increase of the number of passes. The thickness of the intermediate slab after the third hot roughing is 35-45mm, the final rolling temperature of the third hot roughing is 370-410℃, the hot finishing four-roller is used for coiling and trimming, the final rolling temperature of the hot finishing is 300-320℃, and the thickness of the strip after hot finishing is 2.5-8mm.

7. The method for preparing aluminum alloy composite plate and strip according to claim 4, characterized in that, The conditions for cold rolling include: the thickness of the strip after cold rolling is 0.5-4 mm, and the total processing rate of cold rolling is 50-80%.

8. The method for preparing aluminum alloy composite plate and strip according to claim 4, characterized in that, The conditions for solution quenching include: a solution temperature of 510-570℃, a solution time of 10-100s, and water cooling to 20-30℃ after solution treatment.

9. The method for preparing aluminum alloy composite plate and strip according to claim 4, characterized in that, The stretching conditions include: stretching and straightening the solution-treated and water-cooled strip and sheet material, with a stretching rate of 0-0.5%.

10. The method for preparing aluminum alloy composite plate and strip according to claim 4, characterized in that, The aging conditions include: the temperature of the sheet / strip is 155-175℃, the holding time is 4-20h, after holding, it is cooled to 150℃ at a rate of 10-20℃ / h, and then naturally cooled to 20-30℃.

Images