High-binding-rate 625 / X65 nickel-based alloy layered composite plate and production method thereof

Abstract

The invention relates to a high-binding-rate 625 / X65 nickel-based alloy layered composite plate and a production method thereof. The production method comprises the following steps: (1) selecting an assembly raw material; (2) polishing the surface to be contacted; (3) forming a 625 / X65 composite blank; (4) end face coping; (5) carrying out lap-joint seal welding and vacuumizing; (6) heating for the first time; (7) rolling for the first time; (8) heating for the second time; (9) carrying out a second round of rolling; and (10) trimming to obtain the 625 / X65 nickel-based alloy layered composite plate with the target specification. According to the invention, 2-3 625 nickel-based alloy plates are compounded with one X65 low-alloy steel plate, so that the produced 625 / X65 nickel-based alloy laminated composite plate is high in interface bonding rate and good in stability, the synchronous deformation rate of base layer and composite layer metal is high, the plate shape is flat, the production process is simple, and the 625 / X65 nickel-based alloy laminated composite plate is suitable for large-scale industrial production of flat plates and rolled plates.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite plate production, and particularly relates to a high-bonding-rate 625 / X65 nickel-based alloy layered composite plate and a production method thereof. BACKGROUND

[0002] Based on excellent corrosion resistance, nickel-based alloys are widely used in petrochemical industry, marine engineering and other fields, for preparing reactors, distillation columns, heat exchangers, and deep-sea oil and gas exploitation equipment and pipelines, seawater desalination devices, etc. However, the use of single nickel-based alloy material has the problems of high economic cost and limited overall performance. Specifically, only about one-third of the thickness of the traditional nickel-based alloy plate plays a role in corrosion resistance, and the remaining part only serves as a structural support, resulting in serious waste of resources. Therefore, from the perspective of improving economy and optimizing performance, the development and application of nickel-based alloy composite plate has become one of the key ways to solve the above problems.

[0003] The 625 / X65 nickel-based alloy layered composite plate uses 625 nickel-based alloy as the composite layer material and low alloy steel X65 as the base layer material to form a composite structure of "625 nickel-based alloy composite layer + X65 steel base layer". The design concept is to provide necessary structural strength support through the X65 steel base layer, and at the same time, to utilize the 625 nickel-based alloy composite layer to endow the pipeline steel with excellent corrosion resistance. Compared with the traditional way of using single nickel-based alloy plate, the composite plate not only takes into account the corrosion resistance but also significantly reduces the material cost (cost reduction of more than 3 / 4) through structural optimization.

[0004] Currently, the production of composite plates mainly adopts explosion method and rolling method, and the mechanical compounding method is widely used for composite pipes, but the mechanical compounding method realizes compounding by embedding corrosion-resistant alloy pipes and pipeline steel pipes, and no effective metallurgical bonding is formed between them, which is prone to delamination failure during service.

[0005] Chinese patent application with publication number CN101564792A discloses an "explosive welding method of C22 nickel-based alloy composite steel plate", Chinese patent application with publication number CN101559517A discloses an "explosive welding method of C276 nickel-based alloy composite steel plate", Chinese patent application with publication number CN101559527A discloses an "explosive welding method of NO8825 nickel-based alloy composite steel plate", Chinese patent application with publication number CN101559528A discloses an "explosive welding method of NO6059 nickel-based alloy composite steel plate for flue gas desulfurization", and Chinese patent application with publication number CN119282348A discloses an "explosive welding method for preparing ultra-thick large-area composite plate based on nickel-based alloy plate", all of which adopt explosive method to prepare nickel-based alloy composite plate, and realize effective compounding of nickel-based alloy and ordinary steel plate through substrate treatment, composite material treatment, brushing and pairing, explosive compounding, repair welding, heat treatment, subsequent treatment and other processes, thereby saving the use amount of expensive metal. However, due to the limitation of explosive method itself, the production specification size of the composite plate is greatly limited. At the same time, due to the effect of shock wave in the explosion process, the bonding performance stability between the composite interfaces is also poor. In addition, with the popularization of large-scale rolling equipment, this method has gradually withdrawn from the mainstream production field and is only used for production in specific scenarios.

[0006] In recent years, rolling method has become a research hotspot in the academic field due to its advantages of large-scale production and controllable process, and the optimization and innovation practice of related technologies are continuously advancing. The rolling method for preparing laminated metal composite plate is the most cost-effective and efficient, especially suitable for large-scale production of large-size composite plates, which can ensure excellent product size precision and significantly improve production efficiency, and the chemical composition between the composite layers and the base layer metal remains basically unchanged, which has little effect on the material performance, and the performance stability of the composite interface is high and the reliability is good, so it has become the main development direction of future composite plate preparation technology.

[0007] Chinese patent application CN109694989A discloses "an 825 / X70 nickel-based alloy composite plate and its manufacturing method," producing a 5-32mm composite plate with excellent corrosion resistance, suitable for pipeline manufacturing requiring high corrosion resistance while maintaining overall structural mechanical properties. Chinese patent application CN105671424A discloses "a nickel-based alloy composite steel plate for pipelines and its manufacturing method," using a rolling method to prepare the nickel-based alloy composite steel plate for pipelines. Chinese patent application CN104801562A discloses "a manufacturing method for producing steel-nickel / nickel-based alloy composite billets," using a rolling method to prepare the composite billet for nickel-based alloy composite plates. Chinese patent application CN116275922A discloses "a manufacturing method for a nickel-based alloy composite billet." However, the nickel content of the nickel-based alloys used in the above schemes is all below 50%, while many petrochemical and marine engineering projects now have increasingly higher requirements for the corrosion resistance of materials, and the use of 625 nickel-based alloys with a nickel content of more than 60% is increasing. There is an urgent need for a suitable industrial mass production method for 625 nickel-based alloy composite plates with high bonding rate. Summary of the Invention

[0008] This invention provides a high-bonding-rate 625 / X65 nickel-based alloy layered composite plate and its production method. It uses 2 to 3 625 nickel-based alloy plates combined with one X65 low-alloy steel plate. The resulting 625 / X65 nickel-based alloy layered composite plate has a high interface bonding rate and good stability, high synchronous deformation rate of the base layer and cladding metal, flat plate shape, and simple production process. It is suitable for large-scale industrial production of flat plates and coils.

[0009] To achieve the above objectives, the present invention employs the following technical solution: A high-bonding-rate 625 / X65 nickel-based alloy layered composite plate is composed of a 625 nickel-based alloy cladding layer and an X65 low-alloy steel base layer. The 625 nickel-based alloy cladding layer is formed by rolling two to three 625 nickel-based alloy plates side-by-side. The X65 low-alloy steel base layer is formed by rolling one X65 low-alloy steel plate. The chemical composition of the 625 nickel-based alloy cladding layer, by mass percentage, is: C≤0.08%, Si≤0.5%, Mn≤0.5%, Cr: 20.0%–23.0%, Mo: 8.0%–10.0%, Nb: 3.15%–4.15%, Fe≤5%. The chemical composition of the X65 low alloy steel base layer, by mass percentage, is: C: 0.02%–0.08%, Si: 0.15%–0.25%, Mn: 0.65%–1.95%, Cr: 0.05%–0.35%, Mo: 0.05%–0.35%, V: 0.02%–0.06%, Nb≤0.05%, Ni: 0.05%–0.35%, Al≤0.05%, Ti≤0.05%, with the balance being Fe and unavoidable impurity elements.

[0010] A method for producing a high-bonding-ratio 625 / X65 nickel-based alloy layered composite plate includes the following steps: (1) Select X65 low alloy steel plate and 625 nickel-based alloy plate as billet raw materials; (2) Grind the surfaces of X65 low alloy steel plate and 625 nickel-based alloy plate to be contacted, remove rust and oxide layers, and degrease and blow clean the processed surfaces. (3) Take 2 to 3 pieces of 625 nickel-based alloy plate and 1 piece of X65 low alloy steel plate, with the processed surfaces facing each other, and stack them together with 2 to 3 pieces of 625 nickel-based alloy plate on top and 1 piece of X65 low alloy steel plate on the bottom; (4) Grind the circumferential end faces of 2 to 3 pieces of 625 nickel-based alloy plates and X65 low alloy steel plates to ensure that there is no rust, oxide layer and grease within 50 mm on both sides of the mating surface; (5) The 2 to 3 pieces of 625 nickel-based alloy plates after grinding are respectively lapped and sealed with X65 low alloy steel plates, and then vacuumed to form 625 / X65 composite billets. (6) The 625 / X65 composite billet is heated for the first time. The temperature of the first heating is 1000-1200℃. The holding time is calculated based on the thickness of the 625 / X65 composite billet at 0.8-1.2 min / mm. After the temperature is uniform, the temperature is raised to the first heating temperature +100℃. The heating rate is ≥10℃ / min. The holding time is calculated based on the thickness of the 625 nickel-based alloy plate at 0.8-1.2 min / mm. (7) Immediately after the first round of heating, the first round of rolling is carried out. The number of rolling passes is 2 to 3, the single pass reduction rate is 5% to 10%, and the rolling speed is 1 to 2 m / s. (8) After the first round of rolling, the intermediate billet is heated in a second round. The temperature of the second round of heating is 1000-1200℃, and the holding time is calculated according to the thickness of the intermediate billet at 0.8-1.2 min / mm. After uniform heating, the temperature is raised to the second round of heating temperature +100℃, the heating rate is ≥10℃ / min, and the holding time is calculated according to the thickness of the 625 nickel-based alloy plate at 0.8-1.2 min / mm. (9) After the second round of heating, the second round of rolling is carried out immediately. Except for the last pass, the single pass reduction rate of each pass is ≥15%, the total reduction rate is ≥75%, the final rolling temperature is ≥980℃, the rolling is water-cooled, the reddening temperature is 550~600℃, and the 625 / X65 composite plate is obtained after stacking and slow cooling. (10) Trim the edges of the 625 / X65 composite plate to obtain the target size 625 / X65 nickel-based alloy layered composite plate.

[0011] The X65 low alloy steel plate has a length ≤ 4m, a width ≤ 3m, and a thickness ≤ 200mm; the total length of the 625 nickel-based alloy plate is less than the length of the X65 low alloy steel plate, and the total width of the 625 nickel-based alloy plate is less than the width of the X65 low alloy steel plate; the ratio of the thickness of the X65 low alloy steel plate to the total thickness of the 625 nickel-based alloy plate is ≥ 6.

[0012] The X65 low alloy steel plate is stacked in the center with 2 to 3 625 nickel-based alloy plates; the distance between the outermost edge of the X65 low alloy steel plate and the 625 nickel-based alloy plate is 130 to 150 mm; the spacing between the 625 nickel-based alloy plates is 60 to 100 mm; and the welding width at all overlaps is 30 to 50 mm.

[0013] In step (5), each joint is fully welded, and the weld height is not higher than the top surface of the 625 nickel-based alloy plate.

[0014] In step (5), a steel pipe is pre-embedded in the middle of the perimeter of the 625 nickel-based alloy plate during sealing welding. After sealing welding, a vacuum is drawn through the pre-embedded steel pipe, with a vacuum degree ≤ 4.5 × 10⁻⁶. -2 Pa; After vacuuming, use hydraulic clamps to seal the pipe opening.

[0015] The thickness of the 625 / X65 nickel-based alloy layered composite plate is 10-40 mm.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1) By using 2 to 3 625 nickel-based alloy plates combined with one X65 low alloy steel plate, the stress concentration at the composite interface of the 625 / X65 composite billet during rolling and cooling is effectively reduced, making the interface stress distribution of the 625 / X65 composite plate more uniform; preventing delamination and tearing of the composite interface under deformation stress, ensuring the bonding quality of the composite interface and improving the bonding rate.

[0017] 2) When assembling the billet, the 625 nickel-based alloy plate is 130-150mm inward. This ensures a 30-50mm lap welding width on each side, enabling effective welding of the 625 nickel-based alloy plate and the X65 low alloy steel plate. On the other hand, it prevents stress concentration at the interface caused by rapid cooling at the corners during the rolling and cooling process of the 625 / X65 composite billet, thus avoiding delamination and tearing of the composite interface under deformation stress and ensuring the bonding quality of the interface.

[0018] 3) Two-stage heating is used before rolling. On the one hand, it ensures the overall temperature of the 625 / X65 composite billet, which is conducive to the full diffusion reaction between the X65 low alloy steel plate and the 625 nickel-based alloy plate in the subsequent rolling process, forming an effective metallurgical bond. On the other hand, by increasing the temperature of the 625 nickel-based alloy plate, the difference in deformation resistance between the X65 low alloy steel plate and the 625 nickel-based alloy plate is reduced, ensuring the deformation consistency of the X65 low alloy steel plate and the 625 nickel-based alloy plate in the rolling process and improving the synchronous deformation rate.

[0019] 4) During the first round of rolling, a low reduction rate and slow rolling speed were adopted under high temperature conditions. On the one hand, this ensured that the 625 nickel-based alloy plate and the X65 low alloy steel plate had sufficient time to undergo diffusion reaction under high temperature and high pressure conditions. On the other hand, it reduced the deformation stress of the 625 / X65 composite billet after rolling, preventing delamination and tearing defects at the composite interface. Ultimately, this enabled the composite interface to form a preliminary metallurgical bond and ensured a high bonding rate at the composite interface.

[0020] 5) During the second round of rolling, a rolling system with a single-pass reduction rate of ≥15% and a total reduction rate of ≥75% is adopted. On the one hand, this can ensure that the 625 nickel-based alloy plate and the X65 low alloy steel plate form an interatomic bond under high temperature and high pressure conditions, achieving the purpose of rolling composite. On the other hand, if there are blocky, granular impurities or brittle phases at the composite interface, they can also be broken under the action of high pressure and ductility, forming a discontinuous and fine particle distribution, further ensuring the composite quality and performance stability.

[0021] 6) The final rolling temperature during rolling should be ≥980℃. This is to ensure the synchronous deformation rate of the 625 nickel-based alloy plate and the X65 low alloy steel plate during rolling. If the final rolling temperature is too low, the deformation resistance of the 625 nickel-based alloy plate will increase sharply and will be much higher than that of the X65 low alloy steel plate. Under these conditions, the X65 low alloy steel plate is more likely to undergo rolling elongation, while the 625 nickel-based alloy plate is more prone to deformation difficulties. Consequently, during the rolling process, the X65 low alloy steel plate may wrap around the 625 nickel-based alloy plate, making it impossible to control the plate shape or even to roll.

[0022] 7) Water cooling is used after rolling, and the reddening temperature is controlled at 550-600℃. Stacking and slow cooling are also adopted. On the one hand, the ideal microstructure can be obtained by controlling the cooling, so that the 625 / X65 composite plate has suitable strength, good plasticity and low temperature toughness. On the other hand, by limiting the reddening temperature and stacking and slow cooling, the residual stress of rolling can be further reduced, and the composite interface can be prevented from delamination and tearing under stress. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the 625 / X65 nickel-based alloy layered composite plate described in this invention.

[0024] Figure 2 This is a schematic diagram of the assembly of the 625 nickel-based alloy plate and the X65 low-alloy steel plate described in this invention.

[0025] In the diagram: 11-625 nickel-based alloy plate; 21-X65 low-alloy plate; 1-625 nickel-based alloy cladding; 2-X65 low-alloy base layer. Detailed Implementation

[0026] This invention discloses a high-bonding-rate 625 / X65 nickel-based alloy layered composite plate, comprising a 625 nickel-based alloy cladding layer and an X65 low-alloy steel base layer. The 625 nickel-based alloy cladding layer is formed by rolling two to three parallel 625 nickel-based alloy plates; the X65 low-alloy steel base layer is formed by rolling one X65 low-alloy steel plate. The chemical composition of the 625 nickel-based alloy cladding layer, by mass percentage, is: C≤0.08%, Si≤0.5%, Mn≤0.5%, Cr: 20.0%–23.0%, Mo: 8.0%–10.0%, Nb: 3.15%–4.15%. The chemical composition of the X65 low alloy steel base layer, by mass percentage, is: C: 0.02%–0.08%, Si: 0.15%–0.25%, Mn: 0.65%–1.95%, Cr: 0.05%–0.35%, Mo: 0.05%–0.35%, V: 0.02%–0.06%, Nb≤0.05%, Ni: 0.05%–0.35%, Al≤0.05%, Ti≤0.05%, with the balance being Fe and unavoidable impurity elements.

[0027] The method for producing a high-bonding-rate 625 / X65 nickel-based alloy layered composite plate according to the present invention includes the following steps: (1) Select X65 low alloy steel plate (or intermediate billet) and 625 nickel-based alloy plate as billet raw materials.

[0028] (2) Grind the surfaces of X65 low alloy steel plate and 625 nickel-based alloy plate to be contacted, remove rust and oxide layers, and degrease and blow clean the processed surfaces.

[0029] Grinding is preferably performed using machining methods such as planing or milling machines to remove 3-5mm of thickness from the surfaces to be contacted, ensuring flatness after processing. By grinding the surfaces to be contacted, it is ensured that fresh metal is in contact with each other during the rolling process, which helps to form a metallurgical bond between the plates, improves the bonding quality, and avoids defects such as inclusions, porosity, and incomplete bonding.

[0030] (3) Take 2-3 pieces of 625 nickel-based alloy plate 11 and 1 piece of X65 low alloy steel plate 21, with the machined surfaces facing each other, and stack them together with 2-3 pieces of 625 nickel-based alloy plate 11 side by side on top and 1 piece of X65 low alloy steel plate 21 on the bottom (e.g. Figure 1 (As shown).

[0031] The X65 low alloy steel plate has a length ≤ 4m, a width ≤ 3m, and a thickness ≤ 200mm; the total length of the 625 nickel-based alloy plate is less than the length of the X65 low alloy steel plate, and the total width of the 625 nickel-based alloy plate is less than the width of the X65 low alloy steel plate; the ratio of the thickness of the X65 low alloy steel plate to the total thickness of the 625 nickel-based alloy plate is ≥ 6.

[0032] like Figure 1 As shown, the X65 low alloy steel plate is stacked in the center with 2 to 3 625 nickel-based alloy plates; the distance A between the outermost edge of the X65 low alloy steel plate and the 625 nickel-based alloy plate is 130 to 150 mm; the spacing B between the 625 nickel-based alloy plates is 60 to 100 mm; the welding width at all lap joints is 30 to 50 mm, and an lap joint structure is formed around each 625 nickel-based alloy plate.

[0033] (4) Grind the circumferential end faces of 2 to 3 pieces of 625 nickel-based alloy plates and X65 low alloy steel plates to ensure that there are no rust, oxide and grease layers within 50 mm on both sides of the mating surface.

[0034] (5) Two to three 625 nickel-based alloy plates after grinding are lapped and sealed with X65 low alloy steel plates, and then vacuumed to form 625 / X65 composite billets; the contact surfaces between each 625 nickel-based alloy plate and X65 low alloy steel plate are in a vacuum environment.

[0035] Gas shielded welding is preferred for sealing, and welding materials compatible with X65 low alloy steel plates should be selected. All lap joints should be fully welded, and the weld reinforcement should not exceed the top surface of the 625 nickel-based alloy plate.

[0036] During the sealing welding process, steel pipes are pre-embedded in the center of the perimeter of each 625 nickel-based alloy plate. After sealing welding, a vacuum is drawn through the pre-embedded steel pipes, with a vacuum degree ≤ 4.5 × 10⁻⁶. -2 Pa; After evacuation, the steel pipe opening is sealed with hydraulic clamps to create a vacuum environment for the composite interface.

[0037] (6) The 625 / X65 composite billet after vacuuming is heated for the first time (preferably using a bogie-type chamber furnace). The temperature of the first heating is 1000-1200℃, and the holding time is calculated based on the thickness of the 625 / X65 composite billet at 0.8-1.2 min / mm. After homogenization, the temperature is raised to the first heating temperature +100℃, the heating rate is ≥10℃ / min, and the holding time is calculated based on the thickness of the 625 nickel-based alloy plate at 0.8-1.2 min / mm.

[0038] (7) Immediately after the first round of heating, the first round of rolling is carried out. The number of rolling passes is 2 to 3, the single-pass reduction rate is 5% to 10%, and the rolling speed is 1 to 2 m / s.

[0039] (8) After the first rolling, the intermediate billet is heated in the second round. The second round heating temperature is 1000-1200℃, and the holding time is calculated according to the thickness of the intermediate billet at 0.8-1.2 min / mm. After uniform heating, the temperature is raised to the second round heating temperature +100℃, the heating rate is ≥10℃ / min, and the holding time is calculated according to the thickness of the 625 nickel-based alloy plate at 0.8-1.2 min / mm.

[0040] (9) After the second round of heating, the second round of rolling is carried out immediately. Except for the last pass, the single-pass reduction rate of each pass is ≥15%, the total reduction rate is ≥75%, the final rolling temperature is ≥980℃, the rolling is water-cooled, the reddening temperature is 550~600℃, and the 625 / X65 composite plate is obtained after stacking and slow cooling.

[0041] (10) Trim the edges of the 625 / X65 composite plate to obtain a 625 / X65 nickel-based alloy layered composite plate of the target specifications. For example... Figure 2 As shown, it consists of a 625 nickel-based alloy cladding layer 1 and an X65 low-alloy base layer 2. The thickness of the 625 / X65 nickel-based alloy layered composite plate is 10–40 mm.

[0042] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.

[0043]

Example

[0044] Table 1 - Material of X65 Low Alloy Steel Plate Table 2 - Specifications of X65 Low Alloy Steel Plate Table 3-625 Nickel-Based Alloy Plate Material Table 4-625 Nickel-Based Alloy Plate Specifications Table 5 - Assembly and Welding Regulations Table 6 - First Round Heating Schedule Table 7 - First Round Rolling System Table 8 - Second Round Heating Procedure Table 9 - Second Round Rolling System Table 10 - Performance Test Results of Composite Panels The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-bonding-ratio 625 / X65 nickel-based alloy layered composite plate, comprising a 625 nickel-based alloy cladding layer and an X65 low-alloy steel base layer; characterized in that, The 625 nickel-based alloy cladding is formed by rolling 2-3 625 nickel-based alloy plates side by side; the X65 low-alloy steel base layer is formed by rolling 1 X65 low-alloy steel plate; the chemical composition of the 625 nickel-based alloy cladding, by mass percentage, is C≤0.08%, Si≤0.5%, Mn≤0.5%, Cr: 20.0%~23.0%, Mo: 8.0%~10.0%, Nb: 3.15%~4.15%, Fe≤5.0%, Al≤0.4%, Ti≤0.4%, with the balance being... Ni and unavoidable impurity elements; the chemical composition of the X65 low alloy steel base layer, by mass percentage, is C: 0.02%~0.08%, Si: 0.15%~0.25%, Mn: 0.65%~1.95%, Cr: 0.05%~0.35%, Mo: 0.05%~0.35%, V: 0.02%~0.06%, Nb≤0.05%, Ni: 0.05%~0.35%, Al≤0.05%, Ti≤0.05%, with the balance being Fe and unavoidable impurity elements.

2. A method for producing a high-bonding-rate 625 / X65 nickel-based alloy layered composite plate as described in claim 1, characterized in that, Includes the following steps: (1) Select X65 low alloy steel plate and 625 nickel-based alloy plate as billet raw materials; (2) Grind the surfaces of X65 low alloy steel plate and 625 nickel-based alloy plate to be contacted, remove rust and oxide layers, and degrease and blow clean the processed surfaces. (3) Take 2 to 3 pieces of 625 nickel-based alloy plate and 1 piece of X65 low alloy steel plate, with the processed surfaces facing each other, and stack them together with 2 to 3 pieces of 625 nickel-based alloy plate on top and 1 piece of X65 low alloy steel plate on the bottom. (4) Grind the circumferential end faces of 2 to 3 pieces of 625 nickel-based alloy plates and X65 low alloy steel plates to ensure that there is no rust, oxide and grease within 50 mm on both sides of the mating surface; (5) The 2 to 3 pieces of 625 nickel-based alloy plates after grinding are respectively lapped and sealed with X65 low alloy steel plates, and then vacuumed to form 625 / X65 composite billets. (6) The 625 / X65 composite billet is heated for the first time. The temperature of the first heating is 1000-1200℃. The holding time is calculated based on the thickness of the 625 / X65 composite billet at 0.8-1.2 min / mm. After the temperature is uniform, the temperature is raised to the first heating temperature +100℃. The heating rate is ≥10℃ / min. The holding time is calculated based on the thickness of the 625 nickel-based alloy plate at 0.8-1.2 min / mm. (7) Immediately after the first round of heating, the first round of rolling is carried out, with 2 to 3 rolling passes, a single pass reduction rate of 5% to 10%, and a rolling speed of 1 to 2 m / s; (8) After the first round of rolling, the intermediate billet is heated in a second round. The temperature of the second round of heating is 1000-1200℃, and the holding time is calculated according to the thickness of the intermediate billet at 0.8-1.2 min / mm. After uniform heating, the temperature is raised to the second round of heating temperature +100℃, the heating rate is ≥10℃ / min, and the holding time is calculated according to the thickness of the 625 nickel-based alloy plate at 0.8-1.2 min / mm. (9) After the second round of heating, the second round of rolling is carried out immediately. Except for the last pass, the single pass reduction rate of each pass is ≥15%, the total reduction rate is ≥75%, the final rolling temperature is ≥980℃, the rolling is water-cooled, the reddening temperature is 550~600℃, and the 625 / X65 composite plate is obtained after stacking and slow cooling. (10) Trim the edges of the 625 / X65 composite plate to obtain the target size 625 / X65 nickel-based alloy layered composite plate.

3. The high-bonding-rate 625 / X65 nickel-based alloy layered composite plate according to claim 2, characterized in that, The X65 low alloy steel plate has a length ≤ 4m, a width ≤ 3m, and a thickness ≤ 200mm; the total length of the 625 nickel-based alloy plate is less than the length of the X65 low alloy steel plate, and the total width of the 625 nickel-based alloy plate is less than the width of the X65 low alloy steel plate; the ratio of the thickness of the X65 low alloy steel plate to the total thickness of the 625 nickel-based alloy plate is ≥ 6.

4. A high-bonding-ratio 625 / X65 nickel-based alloy layered composite plate according to claim 2 or 3, characterized in that, The X65 low alloy steel plate is stacked in the center with 2 to 3 625 nickel-based alloy plates; the distance between the outermost edge of the X65 low alloy steel plate and the 625 nickel-based alloy plate is 130 to 150 mm; the spacing between the 625 nickel-based alloy plates is 60 to 100 mm; and the welding width at all overlaps is 30 to 50 mm.

5. The high bonding rate 625 / X65 nickel-based alloy layered composite plate according to claim 2, characterized in that, In step (5), each joint is fully welded, and the weld height is not higher than the top surface of the 625 nickel-based alloy plate.

6. The high-bonding-rate 625 / X65 nickel-based alloy layered composite plate according to claim 2, characterized in that, In step (5), a steel pipe is pre-embedded in the middle of the perimeter of the 625 nickel-based alloy plate during sealing welding. After sealing welding, a vacuum is drawn through the pre-embedded steel pipe, with a vacuum degree ≤ 4.5 × 10⁻⁶. -2 Pa; After vacuuming, use hydraulic clamps to seal the pipe opening.

7. The high-bonding-ratio 625 / X65 nickel-based alloy layered composite plate according to claim 2, characterized in that, The thickness of the 625 / X65 nickel-based alloy layered composite plate is 10-40 mm.

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