Acid and alkali resistant stainless steel composite plate and preparation method thereof

Abstract

The invention relates to the technical field of stainless steel composite plate preparation, in particular to an acid and alkali resistant stainless steel composite plate and a preparation method thereof. The acid and alkali resistant stainless steel composite plate comprises a carbon steel surface layer and a modified stainless steel composite layer, wherein the thickness ratio of the carbon steel surface layer to the modified stainless steel composite layer is (7-9): (1-3); the modified stainless steel composite layer comprises a modified stainless steel interface layer, a modified stainless steel transition layer and a modified stainless steel surface layer, and the modified stainless steel interface layer contains 25-40 wt% of carbon steel powder; the modified stainless steel transition layer contains 5-20wt% of carbon steel powder; and the modified stainless steel surface layer contains 10-20wt% of nano silicon carbide. The carbon steel / stainless steel sintered rough blank is prepared in combination with the powder metallurgy technology, then the obtained carbon steel / stainless steel sintered rough blank is subjected to hot rolling and heat treatment, and the prepared finished stainless steel clad steel plate has good interlaminar shear strength and corrosion resistance.

Description

Technical Field

[0001] This application relates to the field of stainless steel composite plate preparation technology, and in particular to an acid and alkali resistant stainless steel composite plate and its preparation method. Background Technology

[0002] Stainless steel composite plates are mainly made by continuously bonding carbon steel as a base material with stainless steel panels on one or both sides. The resulting stainless steel composite plates have both the corrosion resistance, wear resistance and decorative properties of stainless steel and the good mechanical and formability properties of carbon steel. At the same time, most of the stainless steel composite plates are still made with carbon steel as the base material and a small amount of stainless steel as the panel, which can save precious metals such as nickel and chromium, reduce the overall production cost, give full play to the advantages of the characteristics of the two materials, and belong to the new energy-saving materials.

[0003] The existing technology for producing stainless steel composite plates includes a method for producing double-sided stainless steel composite plates, as disclosed in CN104309200A: using plain carbon steel as the base material and austenitic stainless steel as the face material, the stainless steel is poured onto the upper and lower surfaces of the plain carbon steel base material by hot melting, and after cooling, the stainless steel composite plate with interatomic bonding at the interface is produced by continuous cold rolling.

[0004] In the stainless steel composite plates prepared above, a significant decarburized layer exists on the carbon steel side at the interface, affecting the bonding strength between the carbon steel substrate and the stainless steel face material. The uneven microstructure of the carbon steel substrate affects surface smoothness, causing surface defects and leading to a decrease in overall acid and alkali corrosion resistance. Furthermore, the stainless steel face material undergoes intergranular carbide precipitation after solution heat treatment of carbon steel in the stainless steel composite plate, resulting in a decrease in the overall corrosion resistance of the stainless steel composite plate and failing to meet the requirements for high corrosion resistance. Summary of the Invention

[0005] To address the corrosion resistance issues of existing stainless steel composite plates, this application provides an acid and alkali resistant stainless steel composite plate and its preparation method.

[0006] The acid and alkali resistant stainless steel composite plate provided by this invention is achieved through the following technical solution:

[0007] An acid and alkali resistant stainless steel composite plate includes a carbon steel surface layer and a modified stainless steel composite layer laminated to the carbon steel surface layer, wherein the thickness ratio of the carbon steel surface layer to the modified stainless steel composite layer is (7-9):(1-3); the modified stainless steel composite layer includes a modified stainless steel interface layer, a modified stainless steel transition layer, and a modified stainless steel surface layer laminated to the carbon steel surface layer from the inside out; the modified stainless steel interface layer contains 25-40 wt% carbon steel powder with a particle size distribution of 5-75 μm; the modified stainless steel transition layer contains 5-20 wt% carbon steel powder with a particle size distribution of 5-75 μm; and the modified stainless steel surface layer contains 10-20 wt% nano-silicon carbide with a particle size distribution of 20-500 nm.

[0008] This invention combines powder metallurgy technology to prepare carbon steel / stainless steel sintered billets, and then hot-rolls and heat-treats the obtained carbon steel / stainless steel sintered billets. The finished stainless steel composite steel plate has good interlaminar shear strength and corrosion resistance.

[0009] Preferably, the modified stainless steel interface layer is made of the following raw materials in the following mass percentages: 25-40 wt% carbon steel powder with a particle size distribution of 5-75 μm, 0.5-5 wt% nano-silicon carbide with a particle size distribution of 20-500 nm, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm.

[0010] Preferably, the modified stainless steel transition layer is made from the following raw materials in the following mass percentages: 5-20 wt% carbon steel powder with a particle size distribution of 5-75 μm, 5-10 wt% nano-silicon carbide with a particle size distribution of 20-500 nm, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm.

[0011] Preferably, the modified stainless steel surface layer is made from the following raw materials in weight percentages: 10-20 wt% of nano-silicon carbide with a particle size distribution of 20-500 nm, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm.

[0012] Preferably, the modified stainless steel surface layer is made of the following raw materials in weight percentages: 10-20 wt% of nano-silicon carbide with a particle size distribution of 20-500 nm, 0.5-2.0 wt% of nano-iron-coated modified graphene, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm.

[0013] Preferably, the carbon steel surface layer is made of any one of Q195 carbon steel, Q215 carbon steel, Q235 carbon steel, and Q275 carbon steel. Preferably, the austenitic stainless steel powder is any one of 304L stainless steel powder, 316L stainless steel powder, and 904L stainless steel powder. Preferably, the nano-silicon carbide is composed of nano-iron-coated modified silicon carbide nanoparticles and nano-iron-coated modified silicon carbide nanowires, and the mass ratio of the nano-iron-coated modified silicon carbide nanoparticles to the nano-iron-coated modified silicon carbide nanowires is (4-15):1.

[0014] This invention employs composites of nano-silicon carbide in different morphologies to improve the corrosion resistance and mechanical properties of stainless steel composite plates. Furthermore, this invention utilizes in-situ sintering of nano-silicon carbide in different morphologies to form a nano-iron cluster coating structure, improving its compatibility with the iron-based alloy matrix and further enhancing the corrosion resistance and overall mechanical properties of the stainless steel composite plate.

[0015] The present invention provides a method for preparing an acid and alkali resistant stainless steel composite plate, which is achieved through the following technical solution:

[0016] A method for preparing an acid and alkali resistant stainless steel composite plate includes the following steps:

[0017] Step 1: Clean the surface of the carbon steel substrate and set aside.

[0018] Simultaneously, powder metallurgy mixture A is prepared according to the formula of the modified stainless steel interface layer, powder metallurgy mixture B is prepared according to the formula of the modified stainless steel transition layer, and powder metallurgy mixture C is prepared according to the formula of the modified stainless steel surface layer.

[0019] Step 2: Place the carbon steel substrate with the cleaned surface into a forming mold, and add powder metallurgy mixture A, powder metallurgy mixture B, and powder metallurgy mixture C into the forming mold in sequence. The mass ratio of powder metallurgy mixture A, powder metallurgy mixture B, and powder metallurgy mixture C is (1-2):(1-2):(1-2). Cold isostatic pressing is used to form a blank. The obtained blank is placed in a plasma sintering furnace and vacuum sintered at 1300-1400℃ for 2-4 hours to obtain a carbon steel / stainless steel sintered billet.

[0020] Step 3: The obtained carbon steel / stainless steel sintered billet is held at 1150-1200℃ for 1-4 hours, and then hot rolled at 1080-1160℃. The final rolling temperature is 850-880℃, and the total deformation of hot rolling is 85-95%, to obtain a semi-finished stainless steel composite plate.

[0021] Step 4: The semi-finished stainless steel composite plate is solution treated at 1050-1100℃ for 30-120 minutes, then cooled to below 40℃ at 40-100℃ / min, and then annealed at 400-420℃ for 0.5-2 hours to obtain the finished stainless steel composite plate.

[0022] The preparation method of the present invention is relatively simple, without the need for conventional explosive welding or vacuum electron beam sealing welding, with low residual stress, which is beneficial to improving the overall physical and chemical properties, and at the same time facilitates industrial-scale manufacturing.

[0023] Preferably, the cold isostatic pressing parameters in step two are as follows: pressurize at 5-10 MPa / min to 25±5 MPa and hold for 5-10 s, pressurize at 3-6 MPa / min to 70±5 MPa and hold for 15-30 s, pressurize at 0.5-2 MPa / min to 100±5 MPa and hold for 90-120 s, then depressurize at 3-6 MPa / min to 60±5 MPa and hold for 15-30 s, and finally depressurize at 0.5-2 MPa / min to 0 MPa.

[0024] This invention optimizes the cold isostatic pressing process, effectively increasing the relative density of carbon steel / stainless steel sintered billets (≥99.5%), thereby improving the corrosion resistance and overall mechanical properties of stainless steel composite plates.

[0025] In summary, this application has the following advantages:

[0026] 1. This invention combines powder metallurgy technology to prepare carbon steel / stainless steel sintered billets, and then hot-rolls and heat-treats the obtained carbon steel / stainless steel sintered billets. The finished stainless steel composite steel plate has good interlaminar shear strength and corrosion resistance.

[0027] 2. The modified stainless steel panel A that forms an interface layer with the carbon steel substrate in this invention contains carbon steel powder of the same origin as the carbon steel substrate, which can effectively improve the decarburization problem on the carbon steel side at the interface. By improving the overall surface flatness of the stainless steel composite steel plate and reducing the surface area, the overall acid and alkali corrosion resistance is improved.

[0028] 3. The modified stainless steel surface C of the present invention contains 10-20wt% nano-silicon carbide with high acid and alkali corrosion resistance, which endows the stainless steel composite steel plate with excellent acid and alkali corrosion resistance and wear resistance.

[0029] 4. The preparation method of the present invention is relatively simple, without the need for conventional explosive welding or vacuum electron beam sealing welding, resulting in low residual stress, which is beneficial to improving the overall physical and chemical properties, and is also convenient for industrial-scale manufacturing. Detailed Implementation

[0030] To further understand the inventiveness and technical advancements of this invention, the preferred embodiments of this invention will be discussed in detail below with reference to examples and comparative examples.

[0031] Example: An acid and alkali resistant stainless steel composite plate includes a carbon steel surface layer and a modified stainless steel composite layer laminated to the carbon steel surface layer. The thickness ratio of the carbon steel surface layer to the modified stainless steel composite layer is (7-9):(1-3). The modified stainless steel composite layer includes a modified stainless steel interface layer, a modified stainless steel transition layer, and a modified stainless steel surface layer laminated to the carbon steel surface layer from the inside out. The thickness of the modified stainless steel interface layer, the modified stainless steel transition layer, and the modified stainless steel surface layer is (1-2):(1-2):(1-2).

[0032] The modified stainless steel interface layer is formulated as follows, which is made from the following raw materials in the following mass percentages: 25-40wt% carbon steel powder with a particle size distribution of 5-75μm, 0.5-5wt% nano silicon carbide with a particle size distribution of 20-500nm, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75μm.

[0033] The modified stainless steel transition layer is formulated as follows, which is made from the following raw materials by mass percentage: 5-20 wt% carbon steel powder with a particle size distribution of 5-75 μm, 5-10 wt% nano silicon carbide with a particle size distribution of 20-500 nm, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm.

[0034] The modified stainless steel surface layer is formulated as follows, consisting of the following raw materials in weight percentages: 10-20 wt% nano-silicon carbide with a particle size distribution of 20-500 nm, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm. Alternatively, the modified stainless steel surface layer is formulated as follows, consisting of the following raw materials in weight percentages: 10-20 wt% nano-silicon carbide with a particle size distribution of 20-500 nm, 0.5-2.0 wt% nano-iron-coated modified graphene, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm.

[0035] The carbon steel surface layer is made of low-carbon steel, specifically any one of Q195, Q215, Q235, or Q275 carbon steel. The austenitic stainless steel powder is any one of 304L, 316L, or 904L stainless steel powder. Different corrosion-resistant grades of stainless steel powder are selected based on the application.

[0036] Nano-silicon carbide is composed of silicon carbide nanoparticles and nano-iron-coated silicon carbide nanowires, with a mass ratio of (4-15):1. This invention utilizes composites of different morphologies of nano-silicon carbide to improve the corrosion resistance and mechanical properties of stainless steel composite plates. Furthermore, this invention employs in-situ sintering of different morphologies of nano-silicon carbide to form a nano-iron cluster coating structure, improving its compatibility with the iron-based alloy matrix and further enhancing the corrosion resistance and overall mechanical properties of the stainless steel composite plate.

[0037] A method for preparing an acid and alkali resistant stainless steel composite plate includes the following steps:

[0038] Step 1: The surface of the carbon steel substrate is sequentially sandblasted, pickled, washed with water, wiped with alcohol, and dried for later use.

[0039] Simultaneously, powder metallurgy mixture A is prepared according to the formula of the modified stainless steel interface layer, powder metallurgy mixture B is prepared according to the formula of the modified stainless steel transition layer, and powder metallurgy mixture C is prepared according to the formula of the modified stainless steel surface layer.

[0040] Step 2: Place the cleaned carbon steel substrate into a forming mold. Add powder metallurgy mixture A, powder metallurgy mixture B, and powder metallurgy mixture C sequentially to the mold. The mass ratio of powder metallurgy mixture A, powder metallurgy mixture B, and powder metallurgy mixture C is (1-2):(1-2):(1-2). Then, perform cold isostatic pressing. The cold isostatic pressing parameters are as follows: apply pressure at 5-10 MPa / min to 25±5 MPa and hold for 5-10 seconds; apply pressure at 3-6 MPa / min to 70±5 MPa and hold for 15-30 seconds; apply pressure at 0.5-2 MPa / min to 100±5 MPa and hold for 90-120 seconds; then reduce the pressure at 3-6 MPa / min to 60±5 MPa and hold for 15-30 seconds; and finally, apply pressure at 0.5-2 MPa / min to 100±5 MPa and hold for 90-120 seconds. The pressure is reduced from MPa / min to 0MPa to obtain a blank. The obtained blank is placed in a plasma sintering furnace and vacuum sintered at 1300-1400℃ for 2-4 hours to obtain a carbon steel / stainless steel sintered blank.

[0041] Step 3: The obtained carbon steel / stainless steel sintered billet is held at 1150-1200℃ for 1-4 hours, and then hot rolled at 1080-1160℃. The final rolling temperature is 850-880℃, and the total deformation of hot rolling is 85-95%, to obtain a semi-finished stainless steel composite plate.

[0042] Step 4: The semi-finished stainless steel composite plate is solution treated at 1050-1100℃ for 30-120 minutes, then cooled to below 40℃ at 40-100℃ / min, and then annealed at 400-420℃ for 0.5-2 hours to obtain the finished stainless steel composite plate.

[0043] Example 1: An acid and alkali resistant stainless steel composite plate includes a Q235 carbon steel surface layer and a modified stainless steel composite layer laminated to the carbon steel surface layer. The thickness ratio of the carbon steel surface layer to the modified stainless steel composite layer is 8:2. The modified stainless steel composite layer includes a modified stainless steel interface layer, a modified stainless steel transition layer, and a modified stainless steel surface layer laminated to the carbon steel surface layer from the inside out. The thickness ratio of the modified stainless steel interface layer, the modified stainless steel transition layer, and the modified stainless steel surface layer is 2:1:2.

[0044] The modified stainless steel interface layer is formulated as follows, and it is made from the following raw materials by mass percentage: 30 wt% of particle size distribution D 50 =30.5μm carbon steel powder, 2.5wt% of nano-silicon carbide LF-SiC-N100 with an average particle size of 100nm, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0045] The modified stainless steel transition layer is formulated as follows, and it is made from the following raw materials by mass percentage: 12 wt% of particle size distribution D 50 =30.5μm carbon steel powder, 8wt% nano-silicon carbide LF-SiC-N100 with an average particle size of 100nm, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0046] The modified stainless steel surface layer is formulated as follows, which is made from the following raw materials by mass percentage: 15wt% of nano-silicon carbide LF-SiC-N100 with an average particle size of 100nm, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0047] The 304L austenitic stainless steel powder is nitrogen-atomized 304L stainless steel powder from Changsha Tianjiu Metal Materials Co., Ltd., with a specification of 15-53μm and an effective component content of 99.9%, brand name TIJO. The nano-silicon carbide is silicon carbide nanoparticles with an average particle size of 100nm provided by Ningbo Luofei Nanotechnology Co., Ltd., item number: LF-SiC-N100.

[0048] The preparation method of carbon steel powder is as follows: Q235 carbon steel blocks are melted by vacuum melting, and then low-carbon steel alloy composition powder is obtained by gas spraying technology. The particle size distribution D of the obtained carbon steel powder is determined by laser particle size analyzer. 50 =30.5μm.

[0049] A method for preparing an acid and alkali resistant stainless steel composite plate includes the following steps:

[0050] Step 1: The surface of the Q235 carbon steel substrate was sandblasted and the surface roughness Ra of the carbon steel substrate after sandblasting was measured to be 10.8 μm. Then, it was atomized and acid-washed with 0.10 mol / L dilute sulfuric acid for 60 s, rinsed three times with deionized water, wiped with alcohol swabs, and finally dried at 80℃ for 15 minutes for later use.

[0051] Simultaneously, according to the formula for the modified stainless steel interface layer, powder metallurgy mixture A is prepared: 30 parts by weight of particle size distribution D... 50 =30.5μm carbon steel powder, 2.5 parts by weight of nano-silicon carbide LF-SiC-N100 with an average particle size of 100nm (Ningbo Luofei Nanotechnology Co., Ltd.), and 67.5 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53μm were placed in a high-energy planetary ball mill LPB-2L and dispersed by dry ball milling at 200rpm for 30min under nitrogen protection.

[0052] Powder metallurgy mixture B is prepared according to the formula of the modified stainless steel transition layer: 12 parts by weight of particle size distribution D 50 =30.5μm carbon steel powder, 8 parts by weight of nano silicon carbide LF-SiC-N100 with an average particle size of 100nm (Ningbo Luofei Nanotechnology Co., Ltd.), and 80 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53μm were placed in a high-energy planetary ball mill LPB-2L and dispersed by dry ball milling at 200rpm for 30min under nitrogen protection.

[0053] According to the formula of the modified stainless steel surface layer, the powder metallurgy mixture C is prepared: 15 parts by weight of nano silicon carbide LF-SiC-N100 with an average particle size of 100nm and 85 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53μm are placed in a high-energy planetary ball mill LPB-2L and dispersed by dry ball milling at 200rpm for 30min under nitrogen protection.

[0054] Step 2: Place the cleaned Q235 carbon steel substrate into a forming mold. Add powder metallurgy mixture A to the mold and flatten it, then add powder metallurgy mixture B and flatten it, followed by powder metallurgy mixture C and flatten it. The mass ratio of powder metallurgy mixture A, powder metallurgy mixture B, and powder metallurgy mixture C is 2:1:2. Then, perform cold isostatic pressing. The cold isostatic pressing parameters are as follows: pressurize from 10MPa / min to 25MPa and hold for 10s, pressurize from 5MPa / min to 75MPa and hold for 30s, and then pressurize from 1... The pressure is increased from 0 MPa / min to 100 MPa and held for 120 s, then decreased to 60 MPa at 5 MPa / min and held for 30 s, and finally decreased to 0 MPa at 1.0 MPa / min to obtain a blank. The blank is placed in a plasma sintering furnace and heated to 600℃ at 80℃ / min, then heated to 1380℃ at 150℃ / min, and vacuum sintered at 1380℃ for 4.0 h. Then, the blank is air-cooled in the furnace and rapidly cooled to 400℃ at 20℃ / min. The furnace is then opened and the blank is allowed to cool naturally to room temperature to obtain a carbon steel / stainless steel sintered blank with a thickness of 80 mm.

[0055] Step 3: The obtained carbon steel / stainless steel sintered billet is placed in a muffle furnace and heated to 600℃ at 20℃ / min, then heated to 850℃ at 10℃ / min and held for 30 min. Subsequently, the temperature is increased to 1180℃ at 10℃ / min and held for 2 hours. Following this, it undergoes four passes of hot roughing rolling and six passes of hot finishing rolling, with a total hot rolling deformation of 90%. The deformation in the first pass is 20%, the second pass is 15%, and the third pass... The deformation amount is 10% in the fourth hot rough rolling process. After the fourth hot rough rolling process, the temperature is raised to 1150℃ and then subjected to six hot finish rolling processes. The deformation amount is 8% in the first hot finish rolling process, 8% in the second hot finish rolling process, 6% in the third hot finish rolling process, 6% in the fourth hot finish rolling process, 4% in the fifth hot finish rolling process, and 3% in the sixth hot finish rolling process. The final rolling temperature is 850℃, and a semi-finished stainless steel composite plate with a thickness of 8.0mm is obtained.

[0056] Step 4: Place the semi-finished stainless steel composite plate in a muffle furnace, heat it to 600℃ at 20℃ / min, then heat it to 1080℃ at 10℃ / min, and perform a solution treatment at 1080℃ for 45 minutes. Then, cool it down to below 40℃ at 80℃ / min, and then anneal it at 420℃ at 10℃ / min for 2 hours. After naturally cooling to room temperature, the finished stainless steel composite plate can be obtained.

[0057] The difference between Example 2 and Example 1 is that the nano-silicon carbide LF-SiC-N100 in the modified stainless steel composite layer is replaced with nano-iron coated modified silicon carbide nanoparticles.

[0058] Nano-iron coated modified silicon carbide nanoparticles are prepared using the existing sol-gel method, and the specific preparation method is as follows:

[0059] S1. At room temperature, dissolve 5g of ferric nitrate nonahydrate in 75mL of distilled water to obtain a ferric nitrate aqueous solution. Add 10g of nano-silicon carbide LF-SiC-N100 to the ferric nitrate aqueous solution, add a magnetic stir bar and stir magnetically at 200r / min for 15 minutes. Load the solution into an ultrasonic disperser and ultrasonically disperse for 30 minutes at an ultrasonic frequency of 20kHz and an ultrasonic power of 600W. Then add 5wt% ammonia solution until Fe... 3+ After complete precipitation, continue to stir magnetically at 200 r / min for 1 hour, and then let it stand at room temperature for 24 hours to obtain a SiC colloidal system with Fe(OH)3 coated on the surface.

[0060] S2. The Fe(OH)3-coated SiC colloid obtained in S1 was washed three times with distilled water, and then vacuum filtered to obtain solid powder. The solid powder was then placed in a vacuum drying oven to remove moisture. The vacuum drying parameters were as follows: drying at 105℃ for 12 hours. The dried solid powder was placed in an atmosphere tube furnace and heated to 800℃ at 20℃ / min under an air atmosphere. It was then calcined at 800℃ for 3 hours. After cooling to room temperature, the obtained solid powder was placed in an atmosphere tube furnace and a reducing atmosphere, namely a hydrogen-argon mixture, was introduced. The volume ratio of hydrogen to argon in the hydrogen-argon mixture was 1:3. The temperature was increased to 800℃ at 20℃ / min and the reduction reaction was carried out at 800℃ for 4 hours. After the furnace was opened, it was naturally cooled to room temperature to obtain nano-iron-coated modified silicon carbide powder.

[0061] S3. Place the iron-coated silicon carbide powder in a high-energy planetary ball mill LPB-2L, using zirconium oxide as grinding beads and an ethanol-water solution as the dispersion medium. The volume ratio of ethanol to water in the ethanol-water solution is 2:1, and the solid-liquid ratio of the iron-coated silicon carbide powder to the ethanol-water solution is 1:0.8. Under nitrogen protection, mill at 600 rpm for 10 minutes, 300 rpm for 15 minutes, 150 rpm for 15 minutes, and 80 rpm for 60 minutes to obtain iron-coated silicon carbide nanoparticles. The particle size distribution D is determined using a laser particle size analyzer. 50 =128.4nm.

[0062] The difference between Example 3 and Example 1 is that the modified stainless steel interface layer has the following formulation, which is made from the following raw materials by mass percentage: 30wt% particle size distribution D 50=30.5μm carbon steel powder, 0.5wt% silicon carbide nanowires, 2.5wt% nano-silicon carbide LF-SiC-N100 with an average particle size of 100nm, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0063] The modified stainless steel transition layer is formulated as follows, and it is made from the following raw materials by mass percentage: 12 wt% of particle size distribution D 50 =30.5μm carbon steel powder, 1wt% silicon carbide nanowires, 7wt% nano-silicon carbide LF-SiC-N100 with an average particle size of 100nm, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0064] The modified stainless steel surface layer is formulated as follows, which is made from the following raw materials by mass percentage: 2wt% silicon carbide nanowires, 13wt% nano-silicon carbide LF-SiC-N100 with an average particle size of 100nm, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0065] The silicon carbide nanowires are SiCNWs from Guangzhou Hongwu Materials Technology Co., Ltd., with specifications of 100-500nm in diameter and 20-100μm in length. CAS No.: 409-21-2.

[0066] The difference between Example 4 and Example 3 is that the nano-silicon carbide LF-SiC-N100 in the modified stainless steel composite layer is replaced with nano-iron-coated modified silicon carbide nanoparticles prepared in Example 2.

[0067] The difference between Example 5 and Example 4 is that the silicon carbide nanowires in the modified stainless steel composite layer are replaced with iron-coated silicon carbide nanowires. The difference in preparation method between the iron-coated silicon carbide nanowires in Example 5 and the iron-coated silicon carbide nanoparticles in Example 2 is as follows: S1. At room temperature, 5g of ferric nitrate nonahydrate is dissolved in 75mL of distilled water to obtain an aqueous solution of ferric nitrate. 10g of silicon carbide nanowires (SiCNWs) are added to the ferric nitrate aqueous solution, and a magnetic stirrer is added to stir the solution at 200r / min for 15 minutes. The solution is then loaded into an ultrasonic disperser and ultrasonically dispersed at an ultrasonic frequency of 20kHz and an ultrasonic power of 600W for 30 minutes. Subsequently, 5wt% ammonia solution is added until Fe... 3+ After complete precipitation, continue to stir magnetically at 200 r / min for 1 hour, and then let it stand at room temperature for 24 hours to obtain the silicon carbide nanowire SiCNWs colloidal system with Fe(OH)3 coating on the surface. The remaining steps S2 and S3 are the same.

[0068] The difference between Example 6 and Example 5 is that the modified stainless steel interface layer has the following formulation, which is made from the following raw materials by mass percentage: 30wt% particle size distribution D 50 =30.5μm carbon steel powder, 0.5wt% nano-iron coated modified silicon carbide nanowires, 2.5wt% nano-iron coated modified silicon carbide nanoparticles, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0069] The modified stainless steel transition layer is formulated as follows, and it is made from the following raw materials by mass percentage: 12 wt% of particle size distribution D 50 =30.5μm carbon steel powder, 1wt% nano-iron coated modified silicon carbide nanowires, 7wt% nano-iron coated modified silicon carbide nanoparticles, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0070] The modified stainless steel surface layer is formulated as follows, which is made from the following raw materials in the following mass percentages: 2 wt% of nano-iron coated modified silicon carbide nanowires, 13 wt% of nano-iron coated modified silicon carbide nanoparticles, 0.5 wt% of nano-iron coated modified graphene, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53 μm.

[0071] The difference between the preparation methods of graphene coated with iron nanoparticles and the silicon carbide nanoparticles coated with iron nanoparticles in Example 2 is as follows: S1. At room temperature, 2g of ferric nitrate nonahydrate was dissolved in 30mL of distilled water to obtain an aqueous solution of ferric nitrate. 1.0g of hydroxylated graphene was added to the aqueous solution of ferric nitrate, and the mixture was magnetically stirred at 200r / min for 15 minutes. The mixture was then loaded into an ultrasonic disperser and ultrasonically dispersed at an ultrasonic frequency of 20kHz and an ultrasonic power of 600W for 30 minutes. Subsequently, ammonia water with a mass concentration of 5wt% was added until Fe... 3+ After complete precipitation, the mixture was magnetically stirred at 200 r / min for 1 hour and aged at room temperature for 24 hours to obtain the Fe(OH)3@GR system of graphene colloid with Fe(OH)3 coating. Steps S2 and S3 were performed identically. The hydroxylated graphene was selected from Suzhou CarbonFeng Graphene Technology Co., Ltd., product number HQNANO-GR-010, with a thickness of 0.6~1.2 nm, sheet diameter of 0.5~5 μm, and hydroxyl content of 4.0 wt%.

[0072] The difference between Example 7 and Example 5 is that the modified stainless steel composite layer includes modified stainless steel interface layer A1, modified stainless steel interface layer A2, modified stainless steel transition layer B1, modified stainless steel transition layer B2, modified stainless steel transition layer B3, modified stainless steel surface layer C1, and modified stainless steel surface layer C2, which are laminated to the carbon steel surface layer from the inside out. The thickness of modified stainless steel interface layer A1, modified stainless steel interface layer A2, modified stainless steel transition layer B1, modified stainless steel transition layer B2, modified stainless steel transition layer B3, modified stainless steel surface layer C1, and modified stainless steel surface layer C2 is 2:2:1:1:1:1:2.

[0073] The modified stainless steel interface layer A1 is formulated as follows, and it is made from the following raw materials by mass percentage: 35 wt% of particle size distribution D 50 =30.5μm carbon steel powder, 0.25wt% nano-iron coated modified silicon carbide nanowires, 1.25wt% nano-iron coated modified silicon carbide nanoparticles, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0074] The formulation of modified stainless steel interface layer A2 is as follows, which is made from the following raw materials by mass percentage: 25 wt% of particle size distribution D 50 =30.5μm carbon steel powder, 0.5wt% nano-iron coated modified silicon carbide nanowires, 2.5wt% nano-iron coated modified silicon carbide nanoparticles, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0075] The modified stainless steel transition layer B1 is formulated as follows, and it is made from the following raw materials by mass percentage: 18 wt% of particle size distribution D 50 =30.5μm carbon steel powder, 0.75wt% nano-iron coated modified silicon carbide nanowires, 4.25wt% nano-iron coated modified silicon carbide nanoparticles, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0076] The formulation of the modified stainless steel transition layer B2 is as follows, which is made from the following raw materials by mass percentage: 12 wt% of particle size distribution D 50 =30.5μm carbon steel powder, 1.0wt% nano-iron coated modified silicon carbide nanowires, 6.0wt% nano-iron coated modified silicon carbide nanoparticles, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0077] The formulation of the modified stainless steel transition layer B3 is as follows, which is made from the following raw materials by mass percentage: 6 wt% of particle size distribution D 50=30.5μm carbon steel powder, 1.25wt% nano-iron coated modified silicon carbide nanowires, 8.75wt% nano-iron coated modified silicon carbide nanoparticles, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0078] The formula for modified stainless steel surface layer C1 is as follows, which is made from the following raw materials by mass percentage: 1.5 wt% of nano-iron coated modified silicon carbide nanowires, 11.5 wt% of nano-iron coated modified silicon carbide nanoparticles, and the balance being 304L austenitic stainless steel powder with a particle size distribution of 15-53 μm.

[0079] The formula for modified stainless steel surface layer C2 is as follows, which is made from the following raw materials in the following mass percentages: 2.0 wt% of nano-iron coated modified silicon carbide nanowires, 14.0 wt% of nano-iron coated modified silicon carbide nanoparticles, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53 μm.

[0080] A method for preparing an acid and alkali resistant stainless steel composite plate includes the following steps:

[0081] Step 1: The surface of the Q235 carbon steel substrate was sandblasted and the surface roughness Ra of the carbon steel substrate after sandblasting was measured to be 10.8 μm. Then, it was atomized and acid-washed with 0.10 mol / L dilute sulfuric acid for 60 s, rinsed three times with deionized water, wiped with alcohol swabs, and finally dried at 80℃ for 15 minutes for later use.

[0082] Simultaneously, according to the formula of modified stainless steel interface layer A1, powder metallurgy mixture A1 was prepared: 35 parts by weight of particle size distribution D 50 Carbon steel powder with a particle size of 30.5 μm, 0.25 parts by weight of silicon carbide nanowires modified with nano-iron coating, 1.25 parts by weight of silicon carbide nanoparticles modified with nano-iron coating, and 63.5 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53 μm were placed in a high-energy planetary ball mill LPB-2L and dispersed by dry ball milling at 200 rpm for 0.5 h under nitrogen protection.

[0083] Powder metallurgy mixture A2 was prepared according to the formula of modified stainless steel interface layer A2: 25 parts by weight of particle size distribution D 50 Carbon steel powder with a particle size of 30.5 μm, 0.5 parts by weight of silicon carbide nanowires modified with nano-iron coating, 2.5 parts by weight of silicon carbide nanoparticles modified with nano-iron coating, and 72 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53 μm were placed in a high-energy planetary ball mill LPB-2L and dispersed by dry ball milling at 200 rpm for 0.5 h under nitrogen protection.

[0084] Powder metallurgy mixture B1 was prepared according to the formula of modified stainless steel transition layer B1: 18 parts by weight of particle size distribution D 50 Carbon steel powder with a particle size of 30.5 μm, 0.75 parts by weight of silicon carbide nanowires modified with nano-iron coating, 4.25 parts by weight of silicon carbide nanoparticles modified with nano-iron coating, and 77 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53 μm were placed in a high-energy planetary ball mill LPB-2L and dispersed by dry ball milling at 200 rpm for 30 min under nitrogen protection.

[0085] Powder metallurgy mixture B2 was prepared according to the formula of modified stainless steel transition layer B2: 12 parts by weight of particle size distribution D 50 =30.5μm carbon steel powder, 1 part by weight of nano-iron coated modified silicon carbide nanowires, 6 parts by weight of nano-iron coated modified silicon carbide nanoparticles, and 81 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53μm are placed in a high-energy planetary ball mill LPB-2L and dispersed by dry ball milling at 200rpm for 30min under nitrogen protection.

[0086] Powder metallurgy mixture B3 was prepared according to the formula of modified stainless steel transition layer B3: 6 parts by weight of particle size distribution D 50 Carbon steel powder with a particle size of 30.5 μm, 1.25 parts by weight of silicon carbide nanowires modified with nano-iron coating, 8.75 parts by weight of silicon carbide nanoparticles modified with nano-iron coating, and 84 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53 μm were placed in a high-energy planetary ball mill LPB-2L and dispersed by dry ball milling at 200 rpm for 30 min under nitrogen protection.

[0087] Prepare powder metallurgy mixture C1 according to the formula of modified stainless steel surface layer C1: Place 1.5 parts by weight of nano-iron coated modified silicon carbide nanowires, 11.5 parts by weight of nano-iron coated modified silicon carbide nanoparticles, and 87 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53μm in a high-energy planetary ball mill LPB-2L, and disperse by dry ball milling at 200rpm for 30min under nitrogen protection.

[0088] Prepare powder metallurgy mixture C2 according to the formula of modified stainless steel surface layer C2: Place 2.0 parts by weight of nano-iron coated modified silicon carbide nanowires, 14.0 parts by weight of nano-iron coated modified silicon carbide nanoparticles, and 84 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53μm in a high-energy planetary ball mill LPB-2L, and disperse by dry ball milling at 200rpm for 30min under nitrogen protection.

[0089] Step 2: Place the cleaned Q235 carbon steel substrate into a forming mold. Add powder metallurgy mixtures A1, A2, B1, B2, B3, C1, and C2 sequentially to the mold and flatten them. The mass ratio of these mixtures is 2:2:1:1:1:1:2. Then, perform cold isostatic pressing. The cold isostatic pressing parameters are as follows: apply pressure at 10 MPa / min to... The pressure is maintained at 25 MPa for 10 seconds, then increased to 75 MPa at 5 MPa / min and held for 30 seconds, then increased to 100 MPa at 1.0 MPa / min and held for 120 seconds. Subsequently, the pressure is reduced to 60 MPa at 5 MPa / min and held for 30 seconds, and then reduced to 0 MPa at 1.0 MPa / min to obtain a blank. The blank is placed in a plasma sintering furnace and heated to 600°C at 80°C / min, then heated to 1380°C at 150°C / min, and vacuum sintered at 1380°C for 4.0 hours. Afterward, the blank is air-cooled in the furnace and rapidly cooled to 400°C at 20°C / min. The furnace is then opened and the furnace is allowed to cool naturally to room temperature to obtain a carbon steel / stainless steel sintered blank with a thickness of 80 mm. The remaining steps three and four are the same as in Example 1.

[0090] The difference between Example 8 and Example 7 is that the modified stainless steel surface layer C1 has the following formula, which is made from the following raw materials in the following mass percentages: 1.5 wt% of nano-iron coated modified silicon carbide nanowires, 11.5 wt% of nano-iron coated modified silicon carbide nanoparticles, 0.3 wt% of nano-iron coated modified graphene prepared in Example 6, and the balance is 304L austenitic stainless steel powder with a particle size distribution of 15-53 μm.

[0091] The modified stainless steel surface layer C2 is formulated as follows, which is made from the following raw materials in the following mass percentages: 2 wt% of nano-iron coated modified silicon carbide nanowires, 14 wt% of nano-iron coated modified silicon carbide nanoparticles, 0.7 wt% of nano-iron coated modified graphene prepared in Example 6, and the balance being 304L austenitic stainless steel powder with a particle size distribution of 15-53 μm.

[0092] The difference between Comparative Example 1 and Example 1 is that the stainless steel composite plate includes a carbon steel surface layer of Q235 material and a 304 stainless steel surface layer composited on the carbon steel surface layer, with a thickness ratio of 8:2 between the carbon steel surface layer and the 304 stainless steel surface layer. The formulation of the 304 stainless steel surface layer is as follows, which is made from the following raw materials by mass percentage: 15wt% of nano-silicon carbide LF-SiC-N100 with an average particle size of 100nm, and the balance being 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0093] The difference between the preparation method of the stainless steel composite plate in Comparative Example 1 and the preparation method in Example 1 is as follows:

[0094] Step 1: The surface of the carbon steel substrate was sandblasted and the surface roughness Ra of the carbon steel substrate after sandblasting was measured to be 10.8 μm. Then, it was atomized and pickled with 0.10 mol / L dilute sulfuric acid for 60 s, rinsed three times with deionized water, wiped with alcohol cotton pads, and finally dried at 80℃ for 15 minutes for later use. At the same time, according to the formula of 304 stainless steel surface layer, powder metallurgy mixture D was prepared: 15 parts by weight of nano silicon carbide LF-SiC-N100 with an average particle size of 100 nm and 85 parts by weight of 304L austenitic stainless steel powder with a particle size distribution of 15-53 μm were placed in a high-energy planetary ball mill LPB-2L and dispersed by dry ball milling at 200 rpm for 30 min under nitrogen protection.

[0095] Step 2: Place the cleaned carbon steel substrate into a forming mold, add powder metallurgy mixture D to the mold and flatten it. The mass ratio of powder metallurgy mixture D to carbon steel substrate is 2:8. Then, perform cold isostatic pressing. The cold isostatic pressing parameters are as follows: pressurize at 10 MPa / min to 25 MPa and hold for 10 s; pressurize at 5 MPa / min to 75 MPa and hold for 30 s; pressurize at 1.0 MPa / min to 100 MPa and hold for 120 s; then pressurize at 5 MPa / min... The pressure is reduced to 60 MPa and held for 30 seconds, then reduced to 0 MPa at a rate of 1.0 MPa / min to obtain a blank. The blank is placed in a plasma sintering furnace and heated to 600°C at a rate of 80°C / min, then to 1380°C at a rate of 150°C / min. It is then vacuum sintered at 1380°C for 4 hours, followed by air cooling in the furnace and rapid cooling to 400°C at a rate of 20°C / min. The furnace is then opened and allowed to cool naturally to room temperature to obtain a carbon steel / stainless steel sintered blank with a thickness of 80 mm. The remaining steps three and four are the same as in Example 1.

[0096] The difference between Comparative Example 2 and Example 1 is that the stainless steel composite plate includes a carbon steel surface layer of Q235 material and a 304 stainless steel surface layer composited on the carbon steel surface layer, with a thickness ratio of 8:2 between the carbon steel surface layer and the 304 stainless steel surface layer. The 304 stainless steel surface layer is formed by cold isostatic pressing, plasma vacuum sintering, hot rolling, and heat treatment of 304L austenitic stainless steel powder with a particle size distribution of 15-53μm.

[0097] The difference between the preparation method of the stainless steel composite plate in Comparative Example 2 and the preparation method in Example 1 is as follows:

[0098] Step 1: The surface of the carbon steel substrate was sandblasted and the surface roughness Ra of the carbon steel substrate after sandblasting was measured to be 10.8 μm. Then, it was atomized and acid-washed with 0.10 mol / L dilute sulfuric acid for 60 seconds, rinsed three times with deionized water, wiped with alcohol swabs, and finally dried at 80°C for 15 minutes for later use.

[0099] Step 2: Place the cleaned carbon steel substrate into a forming mold. Add 304L austenitic stainless steel powder with a particle size distribution of 15-53μm to the forming mold and flatten it. The mass ratio of 304L austenitic stainless steel powder with a particle size distribution of 15-53μm to the carbon steel substrate is 2:8. Then, perform cold isostatic pressing. The cold isostatic pressing parameters are as follows: pressurize at 10MPa / min to 25MPa and hold for 10s; pressurize at 5MPa / min to 75MPa and hold for 30s; pressurize at 1.0MPa / min to 100MPa and hold for 30s. Pressurize for 120 seconds, then reduce the pressure to 60 MPa at 5 MPa / min and hold for 30 seconds, then reduce the pressure to 0 MPa at 1.0 MPa / min to obtain a blank. Place the blank in a plasma sintering furnace and heat it to 600°C at 80°C / min, then heat it to 1380°C at 150°C / min. Vacuum sinter at 1380°C for 4 hours, then air cool it in the furnace and rapidly cool it to 400°C at 20°C / min. After opening the furnace, allow it to cool naturally to room temperature to obtain a carbon steel / stainless steel sintered blank with a thickness of 80 mm. The remaining steps three and four are the same as in Example 1.

[0100] The difference between Comparative Example 3 and Example 1 is that the stainless steel composite plate includes a carbon steel surface layer of Q235 material and a 304 stainless steel surface layer composited on the carbon steel surface layer, with a thickness ratio of 8:2 between the carbon steel surface layer and the 304 stainless steel surface layer. The 304 stainless steel surface layer is formed by casting molten iron from 304L austenitic stainless steel plate, hot rolling, and heat treatment.

[0101] The preparation method of stainless steel composite plate is as follows:

[0102] Step 1: The surface of the carbon steel substrate was sandblasted and the surface roughness Ra of the carbon steel substrate after sandblasting was measured to be 10.8 μm. Then, it was atomized and acid-washed with 0.10 mol / L dilute sulfuric acid for 60 seconds, rinsed three times with deionized water, wiped with alcohol swabs, and finally dried at 80°C for 15 minutes for later use.

[0103] Step 2: Melt the 304L stainless steel block using a vacuum melting method to obtain 304L molten iron. Place the carbon steel substrate with the surface cleaned into a forming mold, pour 304L molten iron into the forming mold, and allow it to cool naturally at room temperature to obtain a carbon steel / stainless steel sintered billet with a thickness of 80mm. The remaining steps 3 and 4 are the same as in Example 1.

[0104] The difference between Comparative Example 4 and Example 1 is that in step two of the preparation method of the stainless steel composite plate, the Q235 carbon steel substrate with the surface cleaned is placed in a forming mold, powder metallurgy mixture A is added to the forming mold and flattened, followed by powder metallurgy mixture B and then powder metallurgy mixture C. The mass ratio of powder metallurgy mixture A, powder metallurgy mixture B, and powder metallurgy mixture C is 2:1:2. Cold isostatic pressing is then performed. The cold isostatic pressing parameters are as follows: 10 MPa / min... The pressure is increased to 100 MPa and held for 190 seconds, then reduced to 0 MPa at 5 MPa / min to obtain a blank. The blank is placed in a plasma sintering furnace and heated to 600°C at 80°C / min, then heated to 1380°C at 150°C / min. It is then vacuum sintered at 1380°C for 4.0 hours, followed by air cooling in the furnace and rapid cooling to 400°C at 20°C / min. The furnace is then opened and allowed to cool naturally to room temperature to obtain a carbon steel / stainless steel sintered blank with a thickness of 80 mm. The remaining steps one, three, and four are the same as in Example 1.

[0105] The difference between Comparative Example 5 and Example 1 is that in step three of the preparation method of stainless steel composite plate, carbon steel / stainless steel sintered billets are placed in a muffle furnace, heated to 600°C at 20°C / min, heated to 850°C at 10°C / min and held for 30 min, then heated to 1180°C at 10°C / min and held for 2 hours, followed by 9 passes of hot rolling treatment, with a deformation amount of 10% in each pass, a total hot rolling deformation amount of 90%, and a final rolling temperature of 850°C, to obtain a semi-finished stainless steel composite plate with a thickness of 8 mm.

[0106] Performance testing: The uniform corrosion rate (mm / year) of stainless steel composite plates in 10% sodium chloride solution and 5% sulfuric acid solution was determined according to national standard GB / T 39534-2020 "Method for determination of uniform corrosion rate of stainless steel and nickel-based alloys in corrosive liquids". Shear strength testing method: Determined according to GB / T6396-2008 "Test methods for mechanical and technological properties of composite steel plates".

[0107] Table 1: Test parameters of stainless steel composite plates in Examples 1-8 and Comparative Examples 1-5

[0108] Shear strength (MPa) Uniform corrosion rate in 10% sodium chloride solution (mm / year) Uniform corrosion rate in 5% sulfuric acid solution (mm / year) Rockwell hardness (HRB) Elongation (%) Example 1 325.4 0.0036 0.0017 92.5 23.8 Example 2 331.2 0.0031 0.0014 92.5 24.5 Example 3 327.1 0.0038 0.0018 92.0 26.1 Example 4 333.7 0.0032 0.0014 92.5 26.9 Example 5 336.2 0.0031 0.0013 92.5 27.3 Example 6 320.5 0.0024 0.0008 93.0 24.8 Example 7 343.6 0.0030 0.0011 93.0 28.8 Example 8 328.3 0.0022 0.0007 93.5 26.1 Comparative Example 1 243.1 0.0041 0.0021 92.0 18.7 Comparative Example 2 251.7 0.0067 0.0033 85.5 20.5 Comparative Example 3 265.3 0.0062 0.0028 87.5 21.6 Comparative Example 4 301.9 0.0038 0.0018 92.5 22.9 Comparative Example 5 293.6 0.0045 0.0026 91.5 19.8

[0109] As can be seen from Example 1 and Comparative Examples 1-3, and Table 1, the stainless steel composite steel plate prepared in this invention has good interlaminar shear strength and chemical corrosion resistance.

[0110] As can be seen from Example 1 and Comparative Example 4, and Table 1, the cold isostatic pressing process of the present invention can improve the interlaminar shear strength of stainless steel composite plates and has a positive effect on chemical corrosion resistance.

[0111] As can be seen from Example 1 and Comparative Example 5, and Table 1, the 4-pass hot roughing and 6-pass hot finishing processes of the present invention can significantly improve the interlaminar shear strength and chemical corrosion resistance of stainless steel composite plates.

[0112] As can be seen from Examples 1 and 2-5 and Table 1, surface coating of nano-silicon carbide with nano-iron clusters can improve the interlaminar shear strength and chemical corrosion resistance of stainless steel composite plates.

[0113] As can be seen from Examples 5 and 6-8 and Table 1, the addition of graphene modified with nano-iron coating can significantly improve the chemical corrosion resistance of stainless steel composite plates, while the interlaminar shear strength decreases. However, the shear strength is ≥300MPa, and the interlaminar shear strength is still good.

[0114] Combining Examples 5 and 7-8 with Table 1, it can be seen that the modified stainless steel interface layer, consisting of modified stainless steel interface layer A1, modified stainless steel interface layer A2, modified stainless steel transition layer B1, modified stainless steel transition layer B2, modified stainless steel transition layer B3, modified stainless steel surface layer C1, and modified stainless steel surface layer C2, which are composited from the inside out on the carbon steel surface layer, produces a modified stainless steel composite steel plate with better interlaminar shear strength and chemical corrosion resistance, but inevitably increases the cost.

[0115] In summary, this invention combines powder metallurgy technology to prepare carbon steel / stainless steel sintered billets, and then hot-rolls and heat-treats the obtained carbon steel / stainless steel sintered billets. The resulting finished stainless steel composite steel plate has good interlaminar shear strength (shear strength ≥300MPa, national standard ≥210MPa) and a uniform corrosion rate ≤0.004mm / year in 10% sodium chloride solution and ≤0.002mm / year in 5% sulfuric acid solution.

[0116] It should be noted that this specific embodiment is merely an explanation of the technical solution of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. An acid and alkali resistant stainless steel composite plate, characterized in that: The material comprises a carbon steel surface layer and a modified stainless steel composite layer bonded to the carbon steel surface layer, wherein the thickness ratio of the carbon steel surface layer to the modified stainless steel composite layer is (7-9):(1-3); the modified stainless steel composite layer comprises a modified stainless steel interface layer, a modified stainless steel transition layer, and a modified stainless steel surface layer bonded to the carbon steel surface layer from the inside out; the modified stainless steel interface layer contains 25-40 wt% carbon steel powder with a particle size distribution of 5-75 μm; the modified stainless steel transition layer contains 5-20 wt% carbon steel powder with a particle size distribution of 5-75 μm; and the modified stainless steel surface layer contains 10-20 wt% nano-silicon carbide with a particle size distribution of 20-500 nm.

2. The acid and alkali resistant stainless steel composite plate according to claim 1, characterized in that: The modified stainless steel interface layer is made from the following raw materials in the following mass percentages: 25-40 wt% carbon steel powder with a particle size distribution of 5-75 μm, 0.5-5 wt% nano-silicon carbide with a particle size distribution of 20-500 nm, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm.

3. The acid and alkali resistant stainless steel composite plate according to claim 2, characterized in that: The modified stainless steel transition layer is made from the following raw materials in the following mass percentages: 5-20 wt% carbon steel powder with a particle size distribution of 5-75 μm, 5-10 wt% nano-silicon carbide with a particle size distribution of 20-500 nm, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm.

4. The acid and alkali resistant stainless steel composite plate according to claim 3, characterized in that: The modified stainless steel surface layer is made from the following raw materials by mass percentage: 10-20 wt% of nano-silicon carbide with a particle size distribution of 20-500 nm, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm.

5. The acid and alkali resistant stainless steel composite plate according to claim 3, characterized in that: The modified stainless steel surface layer is made from the following raw materials in the following mass percentages: 10-20 wt% of nano-silicon carbide with a particle size distribution of 20-500 nm, 0.5-2.0 wt% of nano-iron-coated modified graphene, and the balance being austenitic stainless steel powder with a particle size distribution of 5-75 μm.

6. An acid and alkali resistant stainless steel composite plate according to any one of claims 1-5, characterized in that: The carbon steel surface layer is made of any one of Q195 carbon steel, Q215 carbon steel, Q235 carbon steel, or Q275 carbon steel.

7. An acid and alkali resistant stainless steel composite plate according to any one of claims 1-5, characterized in that: The austenitic stainless steel powder is any one of 304L stainless steel powder, 316L stainless steel powder, and 904L stainless steel powder.

8. An acid and alkali resistant stainless steel composite plate according to any one of claims 1-5, characterized in that: The nano-silicon carbide is composed of silicon carbide nanoparticles modified with iron nanoparticles and silicon carbide nanowires modified with iron nanoparticles, with a mass ratio of (4-15):

1.

9. A method for preparing an acid and alkali resistant stainless steel composite plate according to any one of claims 1-8, characterized in that: Includes the following steps: Step 1: Clean the surface of the carbon steel substrate and set aside. Simultaneously, powder metallurgy mixture A is prepared according to the formula of the modified stainless steel interface layer, powder metallurgy mixture B is prepared according to the formula of the modified stainless steel transition layer, and powder metallurgy mixture C is prepared according to the formula of the modified stainless steel surface layer. Step 2: Place the carbon steel substrate with the cleaned surface into a forming mold, and add powder metallurgy mixture A, powder metallurgy mixture B, and powder metallurgy mixture C into the forming mold in sequence. The mass ratio of powder metallurgy mixture A, powder metallurgy mixture B, and powder metallurgy mixture C is (1-2):(1-2):(1-2). Cold isostatic pressing is used to form a blank. The obtained blank is placed in a plasma sintering furnace and vacuum sintered at 1300-1400℃ for 2-4 hours to obtain a carbon steel / stainless steel sintered billet. Step 3: The obtained carbon steel / stainless steel sintered billet is held at 1150-1200℃ for 1-4 hours, and then hot rolled at 1080-1160℃. The final rolling temperature is 850-880℃, and the total deformation of hot rolling is 85-95%, to obtain a semi-finished stainless steel composite plate. Step 4: The semi-finished stainless steel composite plate is solution treated at 1050-1100℃ for 30-120 minutes, then cooled to below 40℃ at 40-100℃ / min, and then annealed at 400-420℃ for 0.5-2 hours to obtain the finished stainless steel composite plate.

10. The preparation method according to claim 9, characterized in that: The cold isostatic pressing parameters in step two are as follows: pressurize to 25±5MPa at 5-10MPa / min and hold for 5-10s, pressurize to 70±5MPa at 3-6MPa / min and hold for 15-30s, pressurize to 100±5MPa at 0.5-2MPa / min and hold for 90-120s, then depressurize to 60±5MPa at 3-6MPa / min and hold for 15-30s, and finally depressurize to 0MPa at 0.5-2MPa / min.