A nickel composite layer plate and its preparation method and application

Abstract

The present invention relates to a nickel composite layer plate material and a preparation method and application thereof, wherein the nickel composite layer plate material comprises an equiaxed crystal layer, a transition layer and a recrystallization layer, wherein the equiaxed crystal layer and the recrystallization layer are alternately stacked, and the top layer and the bottom layer are both equiaxed crystal layers; the transition layer is located between the equiaxed crystal layer and the recrystallization layer; and the grain sizes of the equiaxed crystal layer, the transition layer and the recrystallization layer are arranged in a gradient. The nickel composite layer plate material provided by the present invention has a unique equiaxed crystal layer-transition layer-recrystallization layer periodic heterogeneous microstructure, coordinates the use performances such as strength, plasticity and corrosion resistance, and has good stability and corrosion resistance, and can meet the comprehensive performance requirements of structural materials under harsh conditions.

Description

Technical Field

[0001] The invention relates to the technical field of metal materials, and in particular to a nickel composite layer plate material and a preparation method and application thereof. Background Art

[0002] The rapid development of modern industry urgently requires new advanced metal materials with comprehensive performance, which not only need to take into account mechanical properties such as strength and plasticity, but also need to have excellent corrosion resistance. In chemical engineering applications, in order to increase the reaction rate, control the reaction direction, and increase the product yield, harsh reaction conditions such as high temperature, high pressure or strong corrosion are required. For example, high-concentration alkali metal ion media are used to treat complex amphoteric metal mineral resources, which can extract valuable metal resources in a green and efficient manner. However, the medium has high alkali concentration, temperature above 180°C, pressure of 4.5MPa, and harsh reaction conditions of stirring slag, which have extremely high requirements on the oxidation resistance, corrosion resistance and mechanical properties of the reactor material.

[0003] Pure nickel has excellent alkali corrosion resistance, oxidation resistance and high temperature stability. However, the mechanical properties of pure nickel are relatively low, and the tensile strength in the annealed state does not exceed 400MPa. High-pressure reaction devices require thicker walls, which leads to increased costs, inconvenient operation, and prone to leakage and other safety issues. Therefore, while maintaining plasticity and corrosion resistance, significantly improving the strength of metal nickel is the development trend of nickel-based materials.

[0004] Nickel has a face-centered cubic crystal structure and can dissolve a large number of alloy atoms to achieve the regulation of material properties. For example, the addition of chromium can simultaneously enhance the strength and oxidation resistance of nickel, and the addition of molybdenum can increase the corrosion resistance of nickel in a reducing environment while strengthening the solid solution. However, high alloying causes problems such as difficulty in processing, cost increase, and difficulty in recycling nickel, which restricts the development and application of nickel and its alloys; by forming specific structures inside the material, such as crystal defects such as dislocations, grain boundaries, twin boundaries, and phase interfaces, the movement of dislocations is hindered, and the strength of the material can be improved. However, the appearance of high-energy defects in the microstructure has an adverse effect on the physical and chemical properties of metal materials such as plasticity, stability, and corrosion resistance. In addition, nickel has high stability and it is difficult to form low-energy defects such as twin boundaries and small-angle interfaces, so there are fewer strengthening technologies available.

[0005] Constructing multi-scale heterogeneous structures is an important means to match and coordinate the multiple properties of metal materials, such as strength, plasticity, and corrosion resistance. It forms two or more microstructure composite materials that can complement each other's performance and achieve gradient transformation. Corresponding to multiple action mechanisms, it can obtain excellent comprehensive performance that homogeneous materials cannot possess.

[0006] CN 113560604A discloses a laser selective melting nickel-based gradient nanocomposite material, a preparation method and an application thereof. The alloy component is prepared in layers by gradient addition of TiB2, which significantly improves the strength while reducing thermal cracks, thus making up for the deficiency of the nickel-based composite material in plasticity.

[0007] CN 108588498A discloses a nickel-based gradient material and a method for preparing the nickel-based gradient material by a selective laser melting method. The grain size of each layer of the nickel-based gradient material changes in a gradient manner and is arranged cyclically in the order of abccba, wherein the average grain sizes of the a layer, the b layer and the c layer are 0.3 μm, 0.6 μm and 1.3 μm, respectively. The nickel-based gradient material can withstand a large load without cracking, and the plasticity and toughness of the nickel-based gradient material are improved on the basis of ensuring the material density and microhardness.

[0008] In the doctoral thesis "Microstructure Evolution and Performance Control of Gradient Structured Inconel 625 Alloy" by Ma Yuanjun of Lanzhou University of Technology, surface mechanical rolling treatment (SMGT) was used to construct a gradient nanotwin structure (GNT) with a thickness of up to 600μm on the surface of Inconel 625 alloy.

[0009] Although the above methods can form heterogeneous microstructures and thus improve the performance of nickel-based alloy materials, the material processing methods not only have high requirements for special equipment, but also need to adjust the composition and state of the nickel-based alloy to meet the preparation requirements. At the same time, the above-mentioned nickel-based alloy materials are smaller in size and have a smaller heterogeneous layer thickness, which is greatly restricted in actual industrial applications.

[0010] In view of the shortcomings of the existing technology, it is necessary to provide a nickel composite layer plate that can be prepared by conventional industrial equipment, has a larger size and excellent mechanical properties. Summary of the invention

[0011] The purpose of the present invention is to provide a nickel composite layer plate material and a preparation method and application thereof. The nickel composite layer plate material is composed of three periodic structures of an equiaxed crystal layer, a transition layer and a recrystallization layer. The preparation process is simple, the process parameters are easy to control and the material structure is highly designable. Large-size products with excellent comprehensive performance can be prepared and can be directly used as engineering materials. It has a prospect of large-scale industrial application.

[0012] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0013] In a first aspect, the present invention provides a nickel composite layer plate, the nickel composite layer plate comprising an equiaxed crystal layer, a transition layer and a recrystallization layer, the equiaxed crystal layer and the recrystallization layer are alternately stacked, and the top layer and the bottom layer are both equiaxed crystal layers; the transition layer is located between the equiaxed crystal layer and the recrystallization layer;

[0014] The grain sizes of the equiaxed crystal layer, the transition layer and the recrystallized layer are arranged in a gradient.

[0015] The nickel composite layer plate provided by the present invention has a unique periodic inhomogeneous microstructure of equiaxed crystal layer-transition layer-recrystallization layer. The grain size of the recrystallization layer is large, and it has better plastic deformation and work hardening capabilities; the equiaxed crystal layer has refined grains, so it can provide higher strength, and the abundant grain boundaries are conducive to the formation of a surface passivation film, thereby improving the corrosion resistance of the plate; the transition layer plays a role in the smooth transition between the equiaxed crystal layer and the recrystallization layer in the microstructure, thereby having a synergistic regulating effect on the material properties. In summary, the periodic inhomogeneous microstructure can coordinate the use properties such as strength, plasticity and corrosion resistance, so that the composite layer plate can meet the comprehensive performance requirements of structural materials under harsh conditions.

[0016] Preferably, the average grain size of the equiaxed crystal layer is 2-10 μm, for example, 2 μm, 4 μm, 6 μm, 8 μm or 10 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the average grain size of the recrystallized layer is 35-150 μm, for example, 35 μm, 50 μm, 75 μm, 100 μm or 150 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the grain size of the transition layer gradually increases from a side adjacent to the equiaxed crystal layer to a side adjacent to the recrystallized layer.

[0019] In a second aspect, the present invention provides a method for preparing the nickel composite layer plate material as described in the first aspect, the preparation method comprising the following steps:

[0020] (1) A pure nickel hot-rolled plate is sequentially cold-rolled and cut to obtain 2N+1 equiaxed crystal plates, where N is a positive integer;

[0021] (2) taking N pieces from the equiaxed crystal plate obtained in step (1) and performing recrystallization heat treatment to obtain a recrystallized plate;

[0022] (3) The equiaxed crystal plate of step (1) and the recrystallized plate obtained in step (2) are cleaned, alternately stacked and fixed, and then heat-treated to obtain a composite plate;

[0023] (4) Annealing the composite plate obtained in step (3) to obtain the nickel composite layer plate.

[0024] The preparation method provided by the present invention adopts conventional pure nickel hot-rolled plates in the industry as raw materials, and through processes such as cold rolling-cutting-heat treatment-surface processing-thermal mechanical processing-annealing, a nickel composite layer plate with alternating arrangement of equiaxed crystal layer-transition layer-recrystallization layer and periodic gradient arrangement of grain size can be obtained. The large-size products can be directly used in practical engineering and can meet the use requirements of structural materials in harsh environments.

[0025] Preferably, the grade of the pure nickel hot-rolled plate in step (1) includes any one of N2, N4, N6 or N8.

[0026] The pure nickel hot-rolled plate is a commercially available pure nickel hot-rolled plate.

[0027] Preferably, the thickness of the pure nickel hot-rolled plate in step (1) is 2-70 mm, for example, 2 mm, 3.5 mm, 6 mm, 50 mm or 70 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the reduction in each pass of the cold rolling process in step (1) does not exceed 10% of the current thickness of the pure nickel hot-rolled plate, for example, it can be 10%, 8%, 5%, 3% or 2%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] Preferably, room temperature water is used to cool the plate between adjacent passes in the cold rolling process of step (1).

[0030] Preferably, the thickness of the pure nickel cold-rolled plate obtained after the cold rolling treatment in step (1) is reduced by 45-75% compared with the thickness of the pure nickel hot-rolled plate, for example, it can be 45%, 55%, 60%, 65% or 75%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] Preferably, the cutting process in step (1) includes any one of electric spark wire cutting, high-pressure water jet cutting, plasma arc cutting or laser cutting, or a combination of at least two of them. Typical but non-limiting combinations include a combination of electric spark wire cutting and laser cutting, a combination of plasma arc cutting and laser cutting, or a combination of electric spark wire cutting, high-pressure water jet cutting, plasma arc cutting and laser cutting.

[0032] Preferably, the sizes of the 2N+1 equiaxed crystal plates in step (1) are all the same.

[0033] Preferably, the temperature of the recrystallization heat treatment in step (2) is 700-1000°C, for example, 700°C, 750°C, 800°C, 900°C or 1000°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, the time of the recrystallization heat treatment in step (2) is 0.5-2 h, for example, 0.5 h, 0.8 h, 1 h, 1.5 h or 2 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] Preferably, the cleaning process in step (3) includes grinding, polishing, immersion, washing and drying performed in sequence.

[0036] The cleaning process can effectively remove impurities such as oxide scale, hard particles and organic pollutants on the surface of the plate, which is conducive to the smooth progress of subsequent processes.

[0037] Preferably, the leaching comprises acid washing and / or alkali washing.

[0038] Preferably, the pickling reagent includes any one of hydrofluoric acid, hydrochloric acid or nitric acid or a combination of at least two thereof. Typical but non-limiting combinations include a combination of hydrofluoric acid and hydrochloric acid, a combination of hydrochloric acid and nitric acid, or a combination of hydrofluoric acid, hydrochloric acid and nitric acid.

[0039] Preferably, the alkali washing reagent comprises a mixed aqueous solution of sodium hydroxide and sodium carbonate.

[0040] Preferably, the cleaning reagent includes any one of deionized water, ethanol or acetone or a combination of at least two of them. Typical but non-limiting combinations include a combination of deionized water and ethanol, a combination of ethanol and acetone, or a combination of deionized water, ethanol and acetone.

[0041] Preferably, the fixing method in step (3) includes welding and / or punching connection.

[0042] Preferably, the thermal processing in step (3) includes warm rolling or vacuum hot pressing.

[0043] The heat treatment can generate metal bonding between the layers of metal sheets. At higher temperatures, the activity of metal atoms is higher, so they tend to migrate between the surfaces of different sheets. The introduction of external forces by rolling, pressing, etc. can provide external power for the migration of metal atoms, thereby promoting the formation of metal bonding between the sheets. The initial microstructures of the layers of metal sheets are different, so the metal atoms will partially retain the structure of the initial material during the migration of the layers of sheets, thereby forming an intermediate transition layer.

[0044] Preferably, the temperature of the warm rolling is 300-600°C, for example, 300°C, 350°C, 400°C, 500°C or 600°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0045] Preferably, the warm rolling is followed by air cooling to room temperature.

[0046] Preferably, the reduction amount in each pass of the warm rolling does not exceed 5% of the current thickness of the composite sheet, and the total deformation amount is 10-30%.

[0047] The reduction in each pass of the warm rolling does not exceed 5% of the current thickness of the composite sheet, for example, it can be 5%, 4%, 3%, 2% or 1%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] The total deformation is 10-30%, for example, 10%, 15%, 20%, 25% or 30%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0049] Preferably, the temperature of the vacuum hot pressing is 450-650°C, for example, 450°C, 500°C, 550°C, 600°C or 650°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0050] Preferably, the pressure of the vacuum hot pressing is 35-65 MPa, for example, 35 MPa, 40 MPa, 50 MPa, 60 MPa or 65 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0051] Preferably, the vacuum hot pressing time is 0.5-2.5 h, for example, 0.5 h, 1 h, 1.5 h, 2 h or 2.5 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0052] Preferably, the temperature of the annealing treatment in step (4) is 700-1000°C, for example, 700°C, 750°C, 800°C, 900°C or 1000°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0053] Preferably, the annealing time in step (4) is 5-30 min, for example, 5 min, 10 min, 15 min, 20 min or 30 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0054] As a preferred technical solution of the preparation method described in the second aspect of the present invention, the preparation method comprises the following steps:

[0055] (1) A pure nickel hot-rolled plate with a thickness of 2-70 mm is sequentially cold-rolled and cut to obtain 2N+1 equiaxed crystal plates, wherein N is a positive integer;

[0056] The reduction amount of each pass in the cold rolling process does not exceed 10% of the current thickness of the pure nickel hot-rolled plate; room temperature water is used to cool the plate between adjacent passes in the cold rolling process; the thickness of the pure nickel cold-rolled plate obtained after the cold rolling process is reduced by 45-75% compared with the thickness of the pure nickel hot-rolled plate;

[0057] (2) taking N pieces from the equiaxed crystal plate obtained in step (1) and subjecting them to recrystallization heat treatment at 700-1000° C. for 0.5-2 h to obtain a recrystallized plate;

[0058] (3) The equiaxed crystal plate of step (1) and the recrystallized plate obtained in step (2) are alternately stacked and fixed after being ground, polished, soaked, cleaned and dried in sequence, and then subjected to heat treatment to obtain a composite plate;

[0059] The thermal processing includes warm rolling or vacuum hot pressing; the temperature of the warm rolling is 300-600°C; the reduction in each pass of the warm rolling does not exceed 5% of the current thickness of the composite plate, and the total deformation is 10-30%; the temperature of the vacuum hot pressing is 450-650°C, the pressure is 35-65MPa, and the time is 0.5-2.5h;

[0060] (4) The composite plate obtained in step (3) is annealed at 700-1000° C. for 5-30 min to obtain the nickel composite layer plate.

[0061] In a third aspect, the present invention provides an application of the nickel composite layer plate material as described in the first aspect, wherein the nickel composite layer plate material is used in the fields of aviation, aerospace, nuclear power, electronics, ocean, mechanical manufacturing or petrochemical industry.

[0062] The nickel composite layer plate provided by the present invention has a heterogeneous gradient structure in which equiaxed crystal layers, transition layers and recrystallization layers are periodically arranged, and therefore has both excellent mechanical properties and good corrosion resistance. The product has a large size and can be industrially produced on a large scale, and has a wide range of applications.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] (1) The nickel composite layer plate provided by the present invention has a unique equiaxed crystal layer-transition layer-recrystallization layer periodic heterogeneous microstructure, which coordinates the use performance such as strength, plasticity and corrosion resistance. The Vickers hardness can reach 526hV, the yield strength can reach 662MPa, the tensile strength can reach 1060MPa, and the elongation can reach 48%. At the same time, it has good stability and corrosion resistance, and can meet the comprehensive performance requirements of structural materials under harsh conditions;

[0065] (2) The raw materials required in the preparation method provided by the present invention are low in cost and easy to obtain, the processing equipment is conventional, the preparation process is simple, the condition parameters are easy to control, the production efficiency is high and the product size is large, which is suitable for large-scale industrial production; at the same time, the performance window of the product is large, and it is easy to apply to the preparation and processing of heterogeneous materials of other types of metals. DETAILED DESCRIPTION

[0066] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0067] Example 1

[0068] The present embodiment provides a nickel composite layer plate material, which includes an equiaxed crystal layer, a transition layer and a recrystallization layer, wherein the equiaxed crystal layer and the recrystallization layer are alternately stacked, and the top layer and the bottom layer are both equiaxed crystal layers; the transition layer is located between the equiaxed crystal layer and the recrystallization layer; the average grain size of the equiaxed crystal layer is 2.14-2.26 μm; the average grain size of the recrystallization layer is 83.1-84.9 μm; the grain size of the transition layer gradually increases from the side adjacent to the equiaxed crystal layer to the side adjacent to the recrystallization layer; the thickness of the nickel composite layer plate material is 7.2 mm.

[0069] The method for preparing the nickel composite layer plate comprises the following steps:

[0070] (1) A pure nickel hot-rolled plate with a thickness of 2 mm and a grade of N6 was subjected to cold rolling and electric spark wire cutting in sequence to obtain 9 rectangular equiaxed crystal plates with a width of 100 mm and a length of 200 mm;

[0071] The reduction amount of each pass in the cold rolling process does not exceed 10% of the current thickness of the pure nickel hot-rolled plate; room temperature water is used to cool the plate between adjacent passes in the cold rolling process; the thickness of the pure nickel cold-rolled plate obtained after the cold rolling process is reduced by 50% compared with the thickness of the pure nickel hot-rolled plate;

[0072] (2) taking four pieces of the equiaxed crystal plates obtained in step (1) and subjecting them to recrystallization heat treatment at 900° C. for 1 h to obtain recrystallized plates;

[0073] (3) The equiaxed crystal plate of step (1) and the recrystallized plate obtained in step (2) are alternately stacked and welded after being ground, polished, pickled with nitric acid, cleaned with ethanol, and dried, and then warm rolled at 400° C. and air-cooled to room temperature to obtain a composite plate; the reduction amount of each pass in the warm rolling does not exceed 5% of the current thickness of the composite plate, and the total deformation amount is 20%;

[0074] (4) The composite plate obtained in step (3) is annealed at 800° C. for 15 min to obtain the nickel composite layer plate.

[0075] Example 2

[0076] The present embodiment provides a nickel composite layer plate material. The preparation method of the nickel composite layer plate material is different from that of the embodiment 1 in that the thickness of the pure nickel hot-rolled plate material in step (1) is adjusted to 3.5 mm, and 5 equiaxed crystal plates are obtained by electric spark wire cutting, of which 2 plates are subjected to recrystallization heat treatment; the nickel composite layer plate material having an average grain size of 2.77-2.83 μm for the equiaxed crystal layer, an average grain size of 84.8-87.2 μm for the recrystallized layer, and a thickness of 7.2 mm is obtained, and the rest is the same as that of the embodiment 1.

[0077] Example 3

[0078] The present embodiment provides a nickel composite layer plate material. The preparation method of the nickel composite layer plate material is different from that of the embodiment 1 in that, in step (1), the thickness of the pure nickel hot-rolled plate material is adjusted to 6 mm, and three equiaxed crystal plates are obtained by electric spark wire cutting, of which one is subjected to recrystallization heat treatment; the nickel composite layer plate material having an average grain size of 2.52-2.68 μm for the equiaxed crystal layer, an average grain size of 87.9-90.1 μm for the recrystallization layer, and a thickness of 7.2 mm is obtained, and the rest is the same as that of the embodiment 1.

[0079] Example 4

[0080] The present embodiment provides a nickel composite layer plate material, which includes an equiaxed crystal layer, a transition layer and a recrystallization layer, wherein the equiaxed crystal layer and the recrystallization layer are alternately stacked, and the top layer and the bottom layer are both equiaxed crystal layers; the transition layer is located between the equiaxed crystal layer and the recrystallization layer; the average grain size of the equiaxed crystal layer is 7.78-7.82 μm; the average grain size of the recrystallization layer is 134.8-141.2 μm; the grain size of the transition layer gradually increases from the side adjacent to the equiaxed crystal layer to the side adjacent to the recrystallization layer; the thickness of the nickel composite layer plate material is 3 mm.

[0081] The method for preparing the nickel composite layer plate comprises the following steps:

[0082] (1) A pure nickel hot-rolled plate with a thickness of 3.5 mm and a grade of N6 was subjected to cold rolling and electric spark wire cutting in sequence to obtain five rectangular equiaxed crystal plates with a width of 100 mm and a length of 200 mm;

[0083] The reduction amount of each pass in the cold rolling process does not exceed 10% of the current thickness of the pure nickel hot-rolled plate; room temperature water is used to cool the plate between adjacent passes in the cold rolling process; the thickness of the pure nickel cold-rolled plate obtained after the cold rolling process is reduced by 75% compared with the thickness of the pure nickel hot-rolled plate;

[0084] (2) taking two pieces of the equiaxed crystal plates obtained in step (1) and subjecting them to recrystallization heat treatment at 1000° C. for 2 h to obtain recrystallized plates;

[0085] (3) The equiaxed crystal plate of step (1) and the recrystallized plate obtained in step (2) are alternately stacked and welded after being ground, polished, pickled with nitric acid, cleaned with ethanol, and dried, and then warm rolled at 300° C. and air-cooled to room temperature to obtain a composite plate; the reduction amount of each pass in the warm rolling does not exceed 5% of the current thickness of the composite plate, and the total deformation amount is 30%;

[0086] (4) The composite plate obtained in step (3) is annealed at 1000° C. for 30 min to obtain the nickel composite layer plate.

[0087] Example 5

[0088] The present embodiment provides a nickel composite layer plate material, which includes an equiaxed crystal layer, a transition layer and a recrystallization layer, wherein the equiaxed crystal layer and the recrystallization layer are alternately stacked, and the top layer and the bottom layer are both equiaxed crystal layers; the transition layer is located between the equiaxed crystal layer and the recrystallization layer; the average grain size of the equiaxed crystal layer is 2.96-2.14 μm; the average grain size of the recrystallization layer is 35.2-36.8 μm; the grain size of the transition layer gradually increases from the side adjacent to the equiaxed crystal layer to the side adjacent to the recrystallization layer; the thickness of the nickel composite layer plate material is 7.8 mm.

[0089] The method for preparing the nickel composite layer plate comprises the following steps:

[0090] (1) A pure nickel hot-rolled plate with a thickness of 3.5 mm and a grade of N6 was subjected to cold rolling and electric spark wire cutting in sequence to obtain five rectangular equiaxed crystal plates with a width of 100 mm and a length of 200 mm;

[0091] The reduction amount of each pass in the cold rolling process does not exceed 10% of the current thickness of the pure nickel hot-rolled plate; room temperature water is used to cool the plate between adjacent passes in the cold rolling process; the thickness of the pure nickel cold-rolled plate obtained after the cold rolling process is reduced by 45% compared with the thickness of the pure nickel hot-rolled plate;

[0092] (2) taking two pieces of the equiaxed crystal plates obtained in step (1) and subjecting them to recrystallization heat treatment at 700° C. for 0.5 h to obtain recrystallized plates;

[0093] (3) The equiaxed crystal plate of step (1) and the recrystallized plate obtained in step (2) are alternately stacked and welded after being ground, polished, pickled with nitric acid, cleaned with ethanol, and dried, and then warm rolled at 600° C. and air-cooled to room temperature to obtain a composite plate; the reduction amount of each pass in the warm rolling does not exceed 5% of the current thickness of the composite plate, and the total deformation amount is 10%;

[0094] (4) The composite plate obtained in step (3) is annealed at 700° C. for 5 min to obtain the nickel composite layer plate.

[0095] Example 6

[0096] This embodiment provides a nickel composite layer plate material. The difference between the preparation method of the nickel composite layer plate material and that of embodiment 1 is that the warm rolling in step (3) is replaced by vacuum hot pressing. The temperature of the vacuum hot pressing is 450° C., the pressure is 35 MPa, and the time is 2.5 h. The rest is the same as that of embodiment 1.

[0097] The average grain size of the equiaxed crystal layer in the obtained nickel composite layer plate is 2.06-2.32 μm, and the average grain size of the recrystallized layer is 83.3-85.6 μm.

[0098] Example 7

[0099] This embodiment provides a nickel composite layer plate material. The difference between the preparation method of the nickel composite layer plate material and that of embodiment 1 is that the warm rolling in step (3) is replaced by vacuum hot pressing. The temperature of the vacuum hot pressing is 650° C., the pressure is 65 MPa, and the time is 0.5 h. The rest is the same as that of embodiment 1.

[0100] The average grain size of the equiaxed crystal layer in the obtained nickel composite layer plate is 2.04-2.21 μm, and the average grain size of the recrystallized layer is 84.1-86.2 μm.

[0101] Comparative Example 1

[0102] This comparative example provides a nickel plate, which is a commercially available pure nickel hot-rolled plate with a grade of N6, a thickness of 8 mm, and an average grain size of 282.9-295.1 μm.

[0103] Comparative Example 2

[0104] This comparative example provides a nickel plate, which is a commercially available pure nickel cold-rolled plate with a grade of N6 and a thickness of 2 mm.

[0105] Comparative Example 3

[0106] This comparative example provides a nickel composite layer plate material, which is different from Example 1 in that the top layer and the bottom layer of the nickel composite layer plate material are both recrystallized layers, and the rest are the same as Example 1.

[0107] The average grain size of the equiaxed crystal layer of the nickel composite layer plate is 1.4-2.9 μm, the average grain size of the recrystallized layer is 83.2-84.9 μm, and the thickness is 7.2 mm.

[0108] The nickel composite layer plates provided in Examples 1-7 and Comparative Example 3 and the nickel plates provided in Comparative Examples 1 and 2 were tested for Vickers hardness, yield strength, tensile strength and elongation using a quasi-static tensile test method. The results are shown in Table 1.

[0109] Table 1

[0110]

[0111]

[0112] It can be seen from Examples 1-7 that the nickel composite layer plate provided by the present invention has excellent comprehensive mechanical properties, with a Vickers hardness of more than 469 HV, more than 520 hV under optimal conditions, a yield strength of more than 418 MPa, more than 600 MPa under optimal conditions, a tensile strength of more than 792 MPa, more than 1000 MPa under optimal conditions, and an elongation of more than 30%, more than 45% under optimal conditions;

[0113] By comparing Example 1 with Examples 2 and 3, it can be seen that, under the premise that the thickness of the nickel composite layer plate is basically close, the comprehensive mechanical properties of the nickel composite layer plate with more layers are better. The composite plate in Example 1 has 9 layers, including 5 equiaxed crystal layers and 4 recrystallization layers, and has the highest tensile strength and plasticity properties; the composite plate in Example 2 has 5 layers, including 3 equiaxed crystal layers and 2 recrystallization layers, and the tensile properties are reduced; the composite plate in Example 3 has 3 layers, including 2 equiaxed crystal layers and 1 recrystallization layer, and the tensile properties are further reduced. However, since the average grain size of the equiaxed crystal layers in Examples 1-3 is very close, the hardness is also relatively close;

[0114] By comparing Example 2 with Examples 4 and 5, it can be seen that the performance of the nickel composite layer plate composed of the same number of layers is determined by the average grain size ratio of the equiaxed crystal layer and the recrystallization layer. In Example 2, the equiaxed crystal layer has fine grains and the recrystallization layer has coarse grains, so it can combine the excellent hardness and strength of the grain material and the good plasticity of the coarse-grained material; in Example 4, the grains of the equiaxed crystal layer and the recrystallization layer are relatively coarse, so the fine grain strengthening effect is limited, the hardness, yield strength and tensile strength are all reduced, and its elongation is only slightly improved; in Example 5, the grains of the equiaxed crystal layer and the recrystallization layer are relatively small, so the synergistic effect of the heterogeneous structure is reduced;

[0115] By comparing Example 1 with Examples 6 and 7, it can be seen that the use of vacuum hot pressing as a thermal mechanical processing method will not significantly change the microstructure of the material, so the performance of the nickel composite layer plate provided by Examples 6 and 7 is close to that of Example 1;

[0116] By comparing Example 1 with Comparative Examples 1 and 2, it can be seen that the nickel composite layer plate provided by the present invention can significantly improve the hardness, strength and plasticity of commercial pure nickel without changing the chemical composition of the material; by comparing Example 1 with Comparative Example 3, it can be seen that the grain size of the equiaxed crystal layer is mainly determined by the annealing treatment process after the plate is composited, the grain size of the recrystallization layer is mainly determined by the recrystallization treatment process after cold rolling, and the thickness of the nickel composite layer plate is determined by the hot working treatment. Therefore, the grain size of each layer of Comparative Example 3 and the thickness of the nickel composite layer plate are not significantly changed compared with Example 1. However, when the top layer and the bottom layer of the nickel composite layer plate are both recrystallization layers, due to the large grain size of the surface material, the surface hardness and corrosion resistance will decrease, and the yield strength and uniform elongation will decrease.

[0117] In summary, the nickel composite layer plate provided by the present invention has a unique equiaxed crystal layer-transition layer-recrystallization layer periodic heterogeneous microstructure, coordinates the use performance such as strength, plasticity and corrosion resistance, and has a Vickers hardness of up to 526hV, a yield strength of up to 662MPa, a tensile strength of up to 1060MPa, and an elongation of up to 48%. At the same time, it has good stability and corrosion resistance, and can meet the comprehensive performance requirements of structural materials under harsh conditions.

[0118] The raw materials required in the preparation method provided by the present invention are low in cost and easy to obtain, the processing equipment is conventional, the preparation process is simple, the condition parameters are easy to control, the production efficiency is high and the product size is large, which is suitable for large-scale industrial production; at the same time, the performance window of the product is large, and it is easy to apply to the preparation and processing of heterogeneous materials of other types of metals.

[0119] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a nickel composite layer plate, characterized in that: The preparation method comprises the following steps: (1) A pure nickel hot-rolled plate is subjected to cold rolling and cutting in sequence to obtain 2N+1 equiaxed crystal plates, where N is a positive integer; (2) taking N pieces from the equiaxed crystal plate obtained in step (1) and performing recrystallization heat treatment to obtain a recrystallized plate; (3) The equiaxed crystal plate of step (1) and the recrystallized plate obtained in step (2) are cleaned, alternately stacked and fixed, and then heat-treated to obtain a composite plate; (4) annealing the composite sheet obtained in step (3) to obtain the nickel composite layer sheet; The nickel composite layer plate comprises an equiaxed crystal layer, a transition layer and a recrystallization layer, wherein the equiaxed crystal layer and the recrystallization layer are alternately stacked, and the top layer and the bottom layer are both equiaxed crystal layers; the transition layer is located between the equiaxed crystal layer and the recrystallization layer; the average grain size of the equiaxed crystal layer is 2-10 μm; the average grain size of the recrystallization layer is 35-150 μm; The grain sizes of the equiaxed crystal layer, the transition layer and the recrystallized layer are arranged in a gradient.

2. The method for preparing the nickel composite layer sheet material according to claim 1, characterized in that: The grade of the pure nickel hot-rolled plate in step (1) includes any one of N2, N4, N6 or N8.

3. The method for preparing the nickel composite layer sheet material according to claim 1, characterized in that: The thickness of the pure nickel hot-rolled plate in step (1) is 2-70 mm.

4. The method for preparing the nickel composite layer sheet material according to claim 1, characterized in that: The reduction in each pass of the cold rolling process in step (1) does not exceed 10% of the current thickness of the pure nickel hot-rolled plate.

5. The method for preparing the nickel composite layer sheet material according to claim 1, characterized in that: In step (1), room temperature water is used to cool the plate between adjacent passes in the cold rolling process.

6. The method for preparing the nickel composite layer sheet material according to claim 1, characterized in that: The thickness of the pure nickel cold-rolled plate obtained after the cold rolling treatment in step (1) is reduced by 45-75% compared with the thickness of the pure nickel hot-rolled plate.

7. The method for preparing the nickel composite layer plate material according to claim 1, characterized in that: The cutting process in step (1) includes any one of electric spark wire cutting, high-pressure water jet cutting, plasma arc cutting or laser cutting, or a combination of at least two of them.

8. The method for preparing the nickel composite layer plate material according to claim 1, characterized in that: The temperature of the recrystallization heat treatment in step (2) is 700-1000°C.

9. The method for preparing the nickel composite layer plate material according to claim 1, characterized in that: The time of the recrystallization heat treatment in step (2) is 0.5-2h.

10. The method for preparing the nickel composite layer plate according to claim 1, characterized in that: The cleaning process in step (3) includes grinding, polishing, immersion, washing and drying in sequence.

11. The method for preparing the nickel composite layer plate according to claim 10, characterized in that: The leaching includes acid washing and / or alkali washing.

12. The method for preparing the nickel composite layer plate material according to claim 11, characterized in that: The pickling reagent includes any one of hydrofluoric acid, hydrochloric acid or nitric acid, or a combination of at least two of them.

13. The method for preparing the nickel composite layer plate material according to claim 11, characterized in that: The alkaline washing reagent includes a mixed aqueous solution of sodium hydroxide and sodium carbonate.

14. The method for preparing the nickel composite layer plate according to claim 10, characterized in that: The cleaning reagent includes any one of deionized water, ethanol or acetone, or a combination of at least two of them.

15. The method for preparing the nickel composite layer plate material according to claim 1, characterized in that: The fixing method in step (3) includes welding and / or punching connection.

16. The method for preparing the nickel composite layer plate material according to claim 1, characterized in that: The thermal processing in step (3) includes warm rolling or vacuum hot pressing.

17. The method for preparing the nickel composite layer plate material according to claim 16, characterized in that: The temperature of the warm rolling is 300-600°C.

18. The method for preparing the nickel composite layer plate material according to claim 16, characterized in that: The reduction in each pass of the warm rolling does not exceed 5% of the current thickness of the composite plate, and the total deformation is 10-30%.

19. The method for preparing the nickel composite layer plate material according to claim 16, characterized in that: The temperature of the vacuum hot pressing is 450-650°C.

20. The method for preparing the nickel composite layer plate material according to claim 16, characterized in that: The pressure of the vacuum hot pressing is 35-65MPa.

21. The method for preparing the nickel composite layer plate material according to claim 16, characterized in that: The vacuum hot pressing time is 0.5-2.5h.

22. The method for preparing the nickel composite layer plate material according to claim 1, characterized in that: The temperature of the annealing treatment in step (4) is 700-1000°C.

23. The method for preparing the nickel composite layer plate material according to claim 1, characterized in that: The annealing time in step (4) is 5-30 minutes.

24. The method for preparing the nickel composite layer plate material according to claim 1, characterized in that: The preparation method comprises the following steps: (1) A pure nickel hot-rolled plate with a thickness of 2-70 mm is sequentially cold-rolled and cut to obtain 2N+1 equiaxed crystal plates, where N is a positive integer; The reduction amount of each pass in the cold rolling process does not exceed 10% of the current thickness of the pure nickel hot-rolled plate; room temperature water is used to cool the plate between adjacent passes in the cold rolling process; the thickness of the pure nickel cold-rolled plate obtained after the cold rolling process is reduced by 45-75% compared with the thickness of the pure nickel hot-rolled plate; (2) taking N pieces from the equiaxed crystal plate obtained in step (1) and subjecting them to recrystallization heat treatment at 700-1000°C for 0.5-2h to obtain a recrystallized plate; (3) The equiaxed crystal plate of step (1) and the recrystallized plate obtained in step (2) are alternately stacked and fixed after being ground, polished, soaked, cleaned and dried in sequence, and then subjected to heat treatment to obtain a composite plate; The thermal processing includes warm rolling or vacuum hot pressing; the temperature of the warm rolling is 300-600°C; the reduction in each pass of the warm rolling does not exceed 5% of the current thickness of the composite plate, and the total deformation is 10-30%; the temperature of the vacuum hot pressing is 450-650°C, the pressure is 35-65MPa, and the time is 0.5-2.5h; (4) The composite plate obtained in step (3) is annealed at 700-1000° C. for 5-30 min to obtain the nickel composite layer plate.

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