High-permeability corrosion-resistant composite metal material and preparation method thereof
Patent Information
- Application Number
- CN202610621140.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-08
- Publication Date
- 2026-08-21
AI Technical Summary
现有技术常采用铁素体不锈钢作为表层材料，然而，在热轧复合过程中，铁素体不锈钢中的Cr易向界面扩散，与Al形成弱磁性的Cr-Al化合物，同时Ni元素会诱发非铁磁性的奥氏体相生成，导致复合材料的导磁性能较未复合的铁素体不锈钢单体显著下降；在耐腐蚀性能方面，铁素体不锈钢的耐蚀性依赖于表面致密的Cr2O3钝化膜，但热轧复合过程中，界面处于无氧环境，钝化膜难以维持，若界面结合不致密，存在微孔隙或连续脆性相，腐蚀介质可沿界面渗透引发缝隙腐蚀，导致复合材料由界面处开始锈蚀、分层；此外，铁素体不锈钢与铝的热膨胀系数差异显著，热轧复合时易在界面生成连续脆性的Fe-Al金属间化合物，如Fe2Al5、FeAl3，导致层间结合强度低，后续加工时易发生分层、起皱，严重制约产品的可靠性和使用寿命
（1）本发明采用铁素体不锈钢作为表层材料，并严格控制Ni含量低于0.4%。Ni是强奥氏体形成元素，当Ni含量超过0.5%时，组织中会出现奥氏体相，而奥氏体为面心立方结构，不具有铁磁性。本发明通过将Ni含量控制在0.4%以下，确保不锈钢组织为纯铁素体（体心立方结构），从而保持优异的软磁性能。同时，将Cr含量精确控制在16.5-17.5%，既保证表面形成致密的Cr2O3钝化膜以维持耐腐蚀性能，又避免Cr含量过高导致弱磁性FeCr金属间化合物析出而劣化导磁性能。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of composite material technology, and more particularly to a high-permeability, corrosion-resistant composite metal material and its preparation method. Background Technology
[0002] Composite metal coils are an important basic material in the hardware manufacturing industry. Stainless steel-aluminum-stainless steel three-layer composite coils have broad application prospects in fields such as electromagnetic heating cookware and home appliance panels due to their symmetrical structure and balanced performance.
[0003] For hardware products used in electromagnetic heating, composite materials are required to possess excellent magnetic permeability. Current technologies often use ferritic stainless steel as the surface material. However, during hot rolling composite processing, Cr in ferritic stainless steel easily diffuses to the interface, forming weakly magnetic Cr-Al compounds with Al. Simultaneously, Ni induces the formation of non-ferromagnetic austenite phases, resulting in a significant decrease in the magnetic permeability of the composite material compared to the uncomposite ferritic stainless steel monomer. Regarding corrosion resistance, the corrosion resistance of ferritic stainless steel relies on a dense Cr2O3 passivation film on its surface. However, during hot rolling composite processing, the interface is in an oxygen-free environment, making it difficult to maintain the passivation film. If the interface bonding is not dense, with micropores or continuous brittle phases, corrosive media can penetrate along the interface, causing crevice corrosion, leading to rust and delamination of the composite material starting from the interface. Furthermore, the significant difference in thermal expansion coefficients between ferritic stainless steel and aluminum makes it easy to form continuous brittle Fe-Al intermetallic compounds, such as Fe2Al5 and FeAl3, at the interface during hot rolling composite processing. This results in low interlayer bonding strength, making delamination and wrinkling prone to occur during subsequent processing, severely restricting product reliability and service life.
[0004] Therefore, achieving high magnetic permeability, high corrosion resistance, and high interfacial bonding strength in composite materials simultaneously is a technical challenge that urgently needs to be solved in this field. Summary of the Invention
[0005] To address the aforementioned problems in the existing technology, this invention provides a high-permeability, corrosion-resistant composite metal material and its preparation method. The composite material is a three-layer composite coil structure of ferritic stainless steel, aluminum alloy, and ferritic stainless steel. High magnetic permeability is ensured by strictly controlling the Ni and Cr content in the ferritic stainless steel. An interface lattice buffer layer is constructed by adding Cu, Mg, Mn, and Zr to the aluminum alloy core layer and controlling the Zr / Mn mass ratio. Ti can be optionally added to enhance high-temperature stability. Combined with hot rolling at 400-440℃ and controlled cooling annealing at 5-10℃ / min, a synergistic effect of high magnetic permeability, high interfacial bonding strength, and good corrosion resistance is achieved.
[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, a high-permeability, corrosion-resistant composite metal material is provided, which is a three-layer composite roll structure, comprising: First ferritic stainless steel layer, aluminum alloy core layer, second ferritic stainless steel layer; The aluminum alloy core layer is disposed between the first ferritic stainless steel layer and the second ferritic stainless steel layer. By weight percentage, the aluminum alloy core layer comprises: Cu 2.5-3.5%, Mg 0.4-1.2%, Mn 0.3-1.0%, Zr 0.15-0.25%, with the balance being Al and unavoidable impurities; Furthermore, the Ni content in both the first ferritic stainless steel layer and the second ferritic stainless steel layer is less than 0.4%, and the Cr content is 16.5-17.5%.
[0007] Furthermore, the aluminum alloy core layer also contains 0.05-0.15% Ti.
[0008] Furthermore, in the aluminum alloy core layer, the mass ratio of Zr to Mn is 0.25-0.35.
[0009] Furthermore, the first ferritic stainless steel layer and the second ferritic stainless steel layer, by mass percentage, also contain: C≤0.08%, Si≤1.0%, Mn≤1.0%, with the balance being Fe and unavoidable impurities.
[0010] Furthermore, the thickness of the first ferritic stainless steel layer and the second ferritic stainless steel layer are each independently 0.1-0.5 mm, and the thickness of the aluminum alloy core layer is 0.1-0.4 mm.
[0011] In a second aspect, a method for preparing the high magnetic permeability and corrosion-resistant composite metallic material described in the first aspect is provided, comprising the following steps: (1) Surface treatment: The surfaces of the ferritic stainless steel strip and aluminum alloy strip to be laminated are degreased and descaled; (2) Billet assembly: The treated aluminum alloy strip is placed between two layers of ferritic stainless steel strip to form a three-layer composite billet of stainless steel-aluminum-stainless steel. (3) Composite rolling: The composite billet is heated to 400-440°C and hot-rolled in a protective atmosphere, with a total reduction rate of 50%-70%, to obtain hot-rolled composite strip; (4) Controlled cooling annealing: The hot-rolled composite strip is cooled in the furnace, and the cooling rate is controlled until the temperature drops. Then it is air-cooled to room temperature to obtain the high magnetic permeability and corrosion resistant composite metal material.
[0012] Further, in step (1), the surface treatment includes: alkaline washing or acid washing of aluminum alloy strip, and mechanical grinding or ultrasonic cleaning of ferritic stainless steel strip.
[0013] Furthermore, in step (3), the rolling speed of the hot-rolled composite is 10-60 m / min, and the final hot rolling temperature is 350-400℃.
[0014] Furthermore, in step (3), the protective atmosphere is nitrogen, argon, or vacuum. Further, in step (4), the controlled cooling rate is 5-10℃ / min until the temperature drops to 250-300℃.
[0015] The beneficial effects of this invention are as follows: (1) This invention uses ferritic stainless steel as the surface material and strictly controls the Ni content to be below 0.4%. Ni is a strong austenite-forming element. When the Ni content exceeds 0.5%, an austenite phase will appear in the microstructure. Austenite has a face-centered cubic structure and does not have ferromagnetism. This invention ensures that the stainless steel microstructure is pure ferrite (body-centered cubic structure) by controlling the Ni content to below 0.4%, thereby maintaining excellent soft magnetic properties. At the same time, the Cr content is precisely controlled at 16.5-17.5%, which ensures the formation of a dense Cr2O3 passivation film on the surface to maintain corrosion resistance, while avoiding the precipitation of weakly magnetic FeCr intermetallic compounds due to excessively high Cr content, which would degrade the magnetic permeability.
[0016] (2) This invention achieves high interfacial bonding strength through three synergistic layers: Al3Zr and Al6Mn nanoparticles are generated in situ at the interface through the synergy of Zr and Mn, constructing a lattice buffer transition layer to reduce interfacial energy. When the Zr / Mn mass ratio is controlled at 0.25-0.35, the particle network distribution is the most uniform and the pinning effect is the best; a trace amount of Ti is introduced to form a (Al,Zr)3Ti composite precipitate with Zr, which has excellent thermal stability at high temperatures of 400-440℃, effectively suppressing grain coarsening; controlled cooling annealing at 5-10℃ / min is used to construct a residual compressive stress field at the interface using the high-temperature creep characteristics of aluminum, offsetting the tensile stress generated by the difference in thermal expansion coefficients during cooling, and preventing the initiation and propagation of interfacial microcracks.
[0017] (3) The ferritic stainless steel on the surface of the composite material of the present invention forms a dense Cr2O3 passivation film, and the interface is fully densely bonded by the controlled cooling process, which blocks the channel for the corrosive medium to penetrate along the interface, thereby giving the composite material good corrosion resistance.
[0018] In summary, this invention achieves a synergistic balance of high magnetic permeability, high bonding strength, and corrosion resistance by controlling the composition of ferritic stainless steel, multi-element microalloying of the aluminum alloy core layer, optimizing the Zr / Mn mass ratio, and combining hot rolling at 400-440℃ with controlled cooling annealing at 5-10℃ / min. Detailed Implementation
[0019] To further illustrate the technical means and effects of the present invention in achieving the intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with preferred embodiments, is provided below.
[0020] Example 1 Ferritic stainless steel layer: 0.3 mm thick, with the following composition by mass percentage: Cr 17.0%, Ni 0.2%, C 0.05%, Si 0.5%, Mn 0.6%, with the balance being Fe and unavoidable impurities.
[0021] Aluminum alloy core layer: 0.2 mm thick, with the following composition by mass percentage: Cu 3.0%, Mg 0.8%, Mn 0.65%, Zr 0.20%, Ti 0.10%, and the balance being Al and unavoidable impurities. The Zr / Mn mass ratio is 0.31.
[0022] (1) Surface treatment: Aluminum alloy strip: Immerse in 20wt% NaOH solution for 5 minutes (temperature 50℃), rinse with hot water, then immerse in 15wt% HNO3 solution for 3 minutes, rinse with cold water, and dry at 100℃ for 5 minutes.
[0023] Ferritic stainless steel strip: Ultrasonic cleaning in metal cleaning agent for 10 minutes (temperature 65℃), rinse with clean water, and dry at 100℃ for 5 minutes.
[0024] (2) Assembly: The treated aluminum alloy strip is placed between two layers of ferritic stainless steel strip, the three layers are aligned and stacked, and then spot welded around the perimeter.
[0025] (3) Composite rolling: The composite billets are fed into a nitrogen-protected heating furnace and heated to 420°C, then held at that temperature for 1.5 hours. They are then fed into a rolling mill for hot rolling composite processing at a rolling speed of 30 m / min, a total reduction of 60%, and a final rolling temperature of 370°C.
[0026] (4) Controlled cooling annealing: The hot-rolled composite strip is cooled in the furnace at a rate of 8°C / min until the temperature drops to 275°C, and then air-cooled to room temperature.
[0027] Example 2 Ferritic stainless steel layer: 0.4 mm thick, with the following composition by mass percentage: Cr 16.5%, Ni 0.3%, C 0.08%, Si 1.0%, Mn 1.0%, with the balance being Fe and unavoidable impurities.
[0028] Aluminum alloy core layer: 0.3mm thick, with a composition of Cu 2.5%, Mg 0.4%, Mn 0.5%, Zr 0.15% by mass, and the balance being Al and unavoidable impurities. The Zr / Mn mass ratio is 0.30.
[0029] (1) Surface treatment: Aluminum alloy strip: Immerse in 20wt% NaOH solution for 5 minutes (temperature 50℃), rinse with hot water, then immerse in 15wt% HNO3 solution for 3 minutes, rinse with cold water, and dry at 100℃ for 5 minutes.
[0030] Ferritic stainless steel strip: Ultrasonic cleaning in metal cleaning agent for 10 minutes (temperature 65℃), rinse with clean water, and dry at 100℃ for 5 minutes.
[0031] (2) Assembly: The treated aluminum alloy strip is placed between two layers of ferritic stainless steel strip, the three layers are aligned and stacked, and then spot welded around the perimeter.
[0032] (3) Composite rolling: The composite billets are fed into a nitrogen-protected heating furnace and heated to 400°C, then held at that temperature for 1.5 hours. They are then fed into a rolling mill for hot rolling composite processing at a rolling speed of 30 m / min, a total reduction of 60%, and a final rolling temperature of 355°C.
[0033] (4) Controlled cooling annealing: The hot-rolled composite strip is cooled in the furnace at a rate of 5°C / min until the temperature drops to 250°C, and then air-cooled to room temperature.
[0034] Example 3 Ferritic stainless steel layer: 0.5 mm thick, with the following composition by mass percentage: Cr 17.5%, Ni 0.2%, C 0.05%, Si 0.5%, Mn 0.6%, with the balance being Fe and unavoidable impurities.
[0035] Aluminum alloy core layer: 0.4 mm thick, with the following composition by mass percentage: Cu 3.5%, Mg 1.2%, Mn 1.0%, Zr 0.25%, Ti 0.15%, and the balance being Al and unavoidable impurities. The Zr / Mn mass ratio is 0.25.
[0036] (1) Surface treatment: Aluminum alloy strip: Immerse in 20wt% NaOH solution for 5 minutes (temperature 50℃), rinse with hot water, then immerse in 15wt% HNO3 solution for 3 minutes, rinse with cold water, and dry at 100℃ for 5 minutes.
[0037] Ferritic stainless steel strip: Ultrasonic cleaning in metal cleaning agent for 10 minutes (temperature 65℃), rinse with clean water, and dry at 100℃ for 5 minutes.
[0038] (2) Assembly: The treated aluminum alloy strip is placed between two layers of ferritic stainless steel strip, the three layers are aligned and stacked, and then spot welded around the perimeter.
[0039] (3) Composite rolling: The composite billets are fed into a nitrogen-protected heating furnace and heated to 440°C, then held at that temperature for 1.5 hours. They are then fed into a rolling mill for hot rolling composite processing at a rolling speed of 30 m / min, a total reduction of 60%, and a final rolling temperature of 395°C.
[0040] (4) Controlled cooling annealing: The hot-rolled composite strip is cooled in the furnace at a rate of 10°C / min until the temperature drops to 290°C, and then air-cooled to room temperature.
[0041] Example 4 Ferritic stainless steel layer: 0.3 mm thick, with the following composition by mass percentage: Cr 17.0%, Ni 0.2%, C 0.05%, Si 0.5%, Mn 0.6%, with the balance being Fe and unavoidable impurities.
[0042] Aluminum alloy core layer: 0.2 mm thick, with the following composition by mass percentage: Cu 3.0%, Mg 0.8%, Mn 0.65%, Zr 0.20%, with the balance being Al and unavoidable impurities. The Zr / Mn mass ratio is 0.31.
[0043] (1) Surface treatment: Aluminum alloy strip: Immerse in 20wt% NaOH solution for 5 minutes (temperature 50℃), rinse with hot water, then immerse in 15wt% HNO3 solution for 3 minutes, rinse with cold water, and dry at 100℃ for 5 minutes.
[0044] Ferritic stainless steel strip: Ultrasonic cleaning in metal cleaning agent for 10 minutes (temperature 65℃), rinse with clean water, and dry at 100℃ for 5 minutes.
[0045] (2) Assembly: The treated aluminum alloy strip is placed between two layers of ferritic stainless steel strip, the three layers are aligned and stacked, and then spot welded around the perimeter.
[0046] (3) Composite rolling: The composite billets are fed into a nitrogen-protected heating furnace and heated to 420°C, then held at that temperature for 1.5 hours. They are then fed into a rolling mill for hot rolling composite processing at a rolling speed of 30 m / min, a total reduction of 60%, and a final rolling temperature of 370°C.
[0047] (4) Controlled cooling annealing: The hot-rolled composite strip is cooled in the furnace at a rate of 8°C / min until the temperature drops to 275°C, and then air-cooled to room temperature.
[0048] Example 5 Ferritic stainless steel layer: 0.5 mm thick, with the following composition by mass percentage: Cr 17.5%, Ni 0.2%, C 0.05%, Si 0.5%, Mn 0.6%, with the balance being Fe and unavoidable impurities.
[0049] Aluminum alloy core layer: 0.4 mm thick, with a composition of Cu 3.5%, Mg 1.2%, Mn 1.0%, Zr 0.25% by mass, and the balance being Al and unavoidable impurities. The Zr / Mn mass ratio is 0.25.
[0050] (1) Surface treatment: Aluminum alloy strip: Immerse in 20wt% NaOH solution for 5 minutes (temperature 50℃), rinse with hot water, then immerse in 15wt% HNO3 solution for 3 minutes, rinse with cold water, and dry at 100℃ for 5 minutes.
[0051] Ferritic stainless steel strip: Ultrasonic cleaning in metal cleaning agent for 10 minutes (temperature 65℃), rinse with clean water, and dry at 100℃ for 5 minutes.
[0052] (2) Assembly: The treated aluminum alloy strip is placed between two layers of ferritic stainless steel strip, the three layers are aligned and stacked, and then spot welded around the perimeter.
[0053] (3) Composite rolling: The composite billets are fed into a nitrogen-protected heating furnace and heated to 440°C, then held at that temperature for 1.5 hours. They are then fed into a rolling mill for hot rolling composite processing at a rolling speed of 30 m / min, a total reduction of 60%, and a final rolling temperature of 395°C.
[0054] (4) Controlled cooling annealing: The hot-rolled composite strip is cooled in the furnace at a rate of 10°C / min until the temperature drops to 290°C, and then air-cooled to room temperature.
[0055] Comparative Example 1 Based on Example 1, the aluminum alloy core layer uses 1060 pure aluminum (Al≥99.6%), which does not contain Cu, Mg, Mn, Zr, or Ti, and other conditions are the same as in Example 1.
[0056] Comparative Example 2 Based on Example 1, the aluminum alloy core layer composition contained 0.6% Mn and 0.25% Zr, with a Zr / Mn mass ratio of 0.42. Other conditions were the same as in Example 1.
[0057] Comparative Example 3 Based on Example 1, the hot rolling temperature is 450°C, and other conditions are the same as in Example 1.
[0058] Comparative Example 4 Based on Example 1, the hot rolling temperature was 380°C, and other conditions were the same as in Example 1.
[0059] Comparative Example 5 Based on Example 1, the ferritic stainless steel layer has a Cr content of 19.0%, and other conditions are the same as in Example 1.
[0060] Comparative Example 6 Based on Example 1, the ferritic stainless steel layer has a Cr content of 15.0%, and other conditions are the same as in Example 1.
[0061] Comparative Example 7 Based on Example 1, after hot rolling and compounding, the product is directly air-cooled to room temperature without furnace controlled cooling, and other conditions are the same as in Example 1.
[0062] Comparative Example 8 Based on Example 1, the Ni content of the ferritic stainless steel layer is 1.1%, and other conditions are the same as in Example 1.
[0063] Performance testing and effect verification The following performance tests were performed on Examples 1-5 and Comparative Examples 1-8. (a) Magnetic permeability test According to GB / T 13012-2008, the magnetic induction intensity B(T) of the composite material was measured using the permeameter method under the conditions of magnetic field strength H=5000 A / m and room temperature.
[0064] (ii) Corrosion resistance test According to GB / T 10125-2021, a neutral salt spray test (NSS) was conducted under the following conditions: 5% NaCl solution, 35°C, and continuous spraying for 72 hours. Corrosion levels were assessed according to GB / T 6461-2022. In this invention, level 9 represents no red rust, no blistering, and very minor defects (defect area ≤0.1%). Level 8 represents slight discoloration or very minor corrosion, with no obvious rust formation (defect area 0.1%-0.25%).
[0065] (III) Interface bonding strength test According to GB / T 6396-2008, a shear strength test was conducted to determine the interfacial shear strength (MPa) of the composite material.
[0066] (iv) Overall performance test results As shown in Table 1 Table 1. Performance test results of each embodiment and comparative example.
[0067] Test results show that Examples 1-5 exhibit excellent overall performance. Compared to the examples, Comparative Example 1 has a shear strength of only 21 MPa, indicating that the alloying modification with a specific ratio of Cu, Mg, Mn, and Zr plays a crucial role in interfacial bonding strength. Comparative Example 2 also shows lower shear strength than the examples, resulting in uneven distribution of interfacial precipitates and a weakened pinning effect. In Comparative Example 3, Fe-Al brittle compounds grow rapidly, forming a continuous brittle layer, which simultaneously degrades magnetic permeability and corrosion resistance. In Comparative Example 4, the aluminum alloy is not sufficiently softened, failing to form an effective metallurgical bond. In Comparative Example 5, the magnetic induction intensity drops to 1.20 T, indicating that exceeding the Cr content limit leads to the precipitation of weakly magnetic FeCr intermetallic compounds, degrading magnetic permeability. In Comparative Example 6, the corrosion level drops to level 8 after 72 hours of salt spray testing, indicating a decrease in corrosion resistance. In Comparative Example 7, the shear strength is lower than the examples, demonstrating that controlled cooling technology plays a key role in eliminating residual interfacial stress and achieving fully dense bonding. The magnetic induction intensity of Comparative Example 8 dropped to 1.26T, indicating that excessive Ni content can induce the formation of non-ferromagnetic austenite phase and reduce magnetic permeability.
[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A high-permeability, corrosion-resistant composite metal material, comprising a three-layer composite roll structure, characterized in that, include: First ferritic stainless steel layer, aluminum alloy core layer, second ferritic stainless steel layer; The aluminum alloy core layer is disposed between the first ferritic stainless steel layer and the second ferritic stainless steel layer. By weight percentage, the aluminum alloy core layer comprises: Cu 2.5-3.5%, Mg 0.4-1.2%, Mn 0.3-1.0%, Zr 0.15-0.25%, with the balance being Al and unavoidable impurities; Furthermore, the Ni content in both the first ferritic stainless steel layer and the second ferritic stainless steel layer is less than 0.4%, and the Cr content is 16.5-17.5%.
2. The high magnetic permeability and corrosion-resistant composite metal material according to claim 1, characterized in that, The aluminum alloy core layer also contains 0.05-0.15% Ti.
3. The high magnetic permeability and corrosion-resistant composite metal material according to claim 1 or 2, characterized in that, In the aluminum alloy core layer, the mass ratio of Zr to Mn is 0.25-0.
35.
4. The high magnetic permeability and corrosion-resistant composite metal material according to claim 1, characterized in that, The first ferritic stainless steel layer and the second ferritic stainless steel layer, by mass percentage, further contain: C≤0.08%, Si≤1.0%, Mn≤1.0%, with the balance being Fe and unavoidable impurities.
5. The high magnetic permeability and corrosion-resistant composite metal material according to claim 1, characterized in that, The thickness of the first ferritic stainless steel layer and the second ferritic stainless steel layer are each independently 0.1-0.5 mm, and the thickness of the aluminum alloy core layer is 0.1-0.4 mm.
6. A method for preparing the high magnetic permeability and corrosion-resistant composite metallic material according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Surface treatment: The surfaces of the ferritic stainless steel strip and aluminum alloy strip to be laminated are degreased and descaled. (2) Billet assembly: The treated aluminum alloy strip is placed between two layers of ferritic stainless steel strip to form a three-layer composite billet of stainless steel-aluminum-stainless steel. (3) Composite rolling: The composite billet is heated to 400-440°C and hot-rolled in a protective atmosphere. The total reduction rate is 50%-70% to obtain hot-rolled composite strip. (4) Controlled cooling annealing: The hot-rolled composite strip is cooled in the furnace, and the cooling rate is controlled until the temperature drops. Then it is air-cooled to room temperature to obtain the high magnetic permeability and corrosion resistant composite metal material.
7. The preparation method according to claim 6, characterized in that, In step (1), the surface treatment includes: alkaline washing or acid washing of aluminum alloy strip, and mechanical grinding or ultrasonic cleaning of ferritic stainless steel strip.
8. The preparation method according to claim 6, characterized in that, In step (3), the rolling speed of the hot-rolled composite is 10-60 m / min, and the final hot rolling temperature is 350-400℃.
9. The preparation method according to claim 6, characterized in that, In step (3), the protective atmosphere is nitrogen, argon or vacuum.
10. The preparation method according to claim 6, characterized in that, In step (4), the controlled cooling rate is 5-10℃ / min until the temperature drops to 250-300℃.