Bimetal composite plate with X90-level composite layer made of nickel-based alloy Inconel625 and manufacturing method of bimetal composite plate with X90-level composite layer made of nickel-based alloy Inconel625

Abstract

The invention discloses a bimetal composite plate with an X90-grade composite layer made of nickel base alloy Inconel625 and a manufacturing method of the bimetal composite plate. The bimetal composite plate comprises the following chemical components in percentage by weight: base material components including C, Si, Mn, Cr, Ni, Mo, Cu, Nb, V, less than or equal to 0.05% of Al, Ti and the balance of Fe and inevitable impurity elements; the composite material comprises the following components: less than or equal to 0.08% of C, less than or equal to 0.5% of Si, less than or equal to 0.5% of Mn, 20.0-23.0% of Cr, 8.0-10.0% of Mo, 3.15-4.15% of Nb, less than or equal to 5.0% of Fe, less than or equal to 0.05% of Al, less than or equal to 0.05% of Ti and the balance of Ni and inevitable impurity elements. According to the invention, the components are comprehensively optimized, and proper rolling and tempering processes are matched to obtain the bimetal composite plate with yield strength not lower than X90 and excellent corrosion resistance for the oil and gas transmission line pipe.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-strength corrosion-resistant structural steel manufacturing, and particularly relates to a production method and composite plate of a bimetallic composite plate with an X90 grade composite layer of nickel-based alloy. - High-strength pipeline steel pipes for oil and gas resources with corrosive media such as... Background Art

[0002] In recent years, my country has gradually increased its development of deep-sea oil and gas resources. Due to the harsh deep-sea environment, there are loads such as waves and earthquakes, which leads to higher and higher requirements for the mechanical properties of pipeline steel. In addition, since marine oil and gas resources contain a large amount of H2S, CO2, Cl - However, limited offshore space makes it difficult to install sufficient corrosive media removal equipment, resulting in incomplete removal of corrosive media. Consequently, conventional pipeline steel cannot meet the safety requirements for deep-sea oil and gas resource transportation, making pipeline perforations and cracking a serious risk.

[0003] In view of this, nickel-based alloy / high-grade pipeline steel composite plates combine the good corrosion resistance of the composite nickel-based alloy with the high strength and toughness of the base pipeline steel. The bimetallic composite pipes made from them can significantly improve the corrosion resistance of the transmission pipeline and extend the service life of the pipeline. At the same time, the material price is relatively low. Therefore, nickel-based alloy / pipeline steel composite plates have good application prospects in replacing single nickel-based alloy pipes. One of the main problems in the production of nickel-based alloy / pipeline steel composite plates is the difficulty in coordinating the deformation of dissimilar metals. It is difficult to achieve a comprehensive match of mechanical properties and corrosion resistance using the same production process.

[0004] Application CN202410772376.8 discloses a "Method for Manufacturing X65-Grade Bimetallic Composite Plates with a Nickel-Based Alloy Cladding." This technical solution utilizes X65 pipeline steel as the base material and Inconel 625 nickel-based alloy as the cladding material. The pipeline steel contains Nb ≤ 0.05% and Ti ≤ 0.05%. The two materials are symmetrically assembled and then rolled in a single stage, with a final rolling temperature of no less than 1000°C. After rolling, the plates are air-cooled and tempered. This significantly differs from the present invention's production process for X90-grade composite plates, which utilizes a high-Nb, high-Ti composition and employs two-stage differential temperature rolling followed by tempering.

[0005] Application CN202410772426.2 discloses a "Method for Manufacturing X80-Grade Bimetallic Composite Plates with Nickel-Based Alloy Cladding." This technical solution utilizes X80 pipeline steel as the base material and Inconel 625 nickel-based alloy as the cladding material. The pipeline steel contains Nb ≤ 0.05% and Ti ≤ 0.05%. The two materials are symmetrically assembled and then rolled in a single stage, with a final rolling temperature of no less than 1000°C. This process is followed by a post-rolling tempering heat treatment. This significantly differs from the present invention's production process, which employs a high-Nb, high-Ti composition followed by two-stage differential rolling followed by tempering.

[0006] Application document CN202410118836.5 announced “A rolling method for Inconel625 / X65 composite plates”. This technical solution adopts asymmetric billet assembly and produces Inconel 625 / X65 composite plates through two-stage rolling. The composite plates have good low-temperature toughness and high interface bonding strength. However, this method does not take into account the corrosion resistance of the Inconel 625 substrate, and only one steel plate can be obtained after the asymmetric billet assembly is divided into plates, and the production efficiency is low. The production process of symmetrical billet assembly and obtaining two composite plates at a time, and ensuring the corrosion resistance of the composite material by differential temperature rolling is quite different from this method.

[0007] Application document CN201410288770.0 discloses a "Method for Manufacturing a Rolled Metal Composite Plate with Pipeline Steel as the Base Material." In this technical solution, the base material is pipeline steel, and the cladding material is corrosion-resistant materials such as austenitic stainless steel, duplex stainless steel, and nickel-based alloys. The two materials are symmetrically assembled and then rolled in two stages. The second stage rolling temperature ranges from 780 to 900°C. After rolling, normalizing treatment or TMCP cooling to 450 to 700°C is selected based on the thickness of the steel plate. This is significantly different from the production process used in the present invention, which uses a two-stage surface base material starting rolling temperature of 960-1000°C, a core cladding material starting rolling temperature of not less than 1000°C, a two-stage finishing rolling temperature of not less than 930°C, and post-rolling tempering.

[0008] Application CN201710983305.2 discloses an "825 / X70 / 825 double-sided composite plate and its production method," while application CN201710983510.9 discloses an "825 / X70 nickel-based alloy composite plate and its production method." The corrosion-resistant layer in these two technical solutions is made of 825 alloy, which contains no less than 22% iron. Its chemical properties are closer to those of the matrix, making it easier to resolve deformation inconsistencies. The final rolling temperature is 760-830°C. The present invention utilizes a 625 nickel-based alloy with an iron content of no more than 5%, and employs a two-stage differential temperature rolling followed by tempering, resulting in significant differences.

[0009] Application CN201710453074.4 discloses a "Method for Preparing Large-Scale, Thin-Layered Nickel-Based Alloy / Pipeline Steel Composite Plates." This technical solution uses explosive welding to prepare composite billets. The composite plates are then produced through asynchronous rolling with a differential speed ratio of 1.05 to 1.30 to overcome the deformation disharmony between the two metals. The present invention utilizes vacuum welding for billet assembly, resulting in metallurgical bonding during the rolling process, which offers significant advantages.

[0010] Application document CN202410909051.X announced "A method for producing a nickel-based 625 and pipeline steel X65M composite plate". This technical solution produces nickel-based 625 and pipeline steel X65M composite plates through two-stage rolling. After the intermediate billet is warmed, the second-stage rolling temperature is 780-820°C, which is significantly different from the second-stage surface substrate rolling temperature of 960-1000°C adopted by the present invention, the core composite material rolling temperature is not lower than 1000°C, the second-stage finishing rolling temperature is not lower than 930°C, and the post-rolling tempering production process is significantly different.

[0011] Application document CN201811017043.5 announced "A nickel-based alloy composite plate for oil and gas pipes and its preparation method". This technical solution produces nickel-based alloy and pipeline steel composite plates through two-stage rolling. The second-stage rolling temperature of this technical solution is lower than 930°C, which is significantly different from the second-stage surface substrate rolling temperature of 960-1000°C adopted by the present invention, the core composite material rolling temperature is not lower than 1000°C, the second-stage finishing rolling temperature is not lower than 930°C, and the post-rolling tempering production process is significantly different.

[0012] In summary, existing technologies address the problem of uneven deformation, using either asynchronous rolling or asymmetric assembly processes to further optimize composite plate performance. Asynchronous rolling imposes stringent requirements on mill capacity, while asymmetric assembly processes can reduce production efficiency and increase costs. Summary of the Invention

[0013] The purpose of the present invention is to provide a bimetallic composite plate with an X90 grade cladding layer of nickel-based alloy Inconel625 and a manufacturing method thereof. By comprehensively optimizing the components of X90 and Inconel 625 and then matching appropriate rolling and tempering processes, a bimetallic composite plate for oil and gas pipelines with a yield strength not lower than X90 and excellent corrosion resistance can be obtained. The present invention overcomes the shortcomings of the existing technical solutions through reasonable component design and optimized matching of the preparation process, and provides a bimetallic composite plate for oil and gas pipelines rich in H2S, CO2, Cl - It provides a new technical solution for the selection of line pipes for transporting oil and gas resources in corrosive media.

[0014] In order to achieve the above object, the present invention adopts the following technical solutions:

[0015] The invention discloses an X90 grade bimetallic composite plate with a cladding layer of nickel-based alloy Inconel625. The chemical composition thereof is as follows, calculated by weight percentage: a base material comprises C 0.02% to 0.08%, Si 0.15% to 0.25%, Mn 0.65% to 1.95%, Cr 0.05% to 0.35%, Ni 0.3% to 0.4%, Mo 0.2% to 0.35%, Cu 0.2% to 0.3%, Nb 0.06% to 0.08%, V 0.02% to 0.05%, Al≤0.05%, Ti 0.06% to 0.08%, and the balance is Fe and unavoidable impurity elements; a composite material comprises C≤0.08%, Si≤0.5%, Mn≤0.5%, Cr 20.0% to 23.0%, Mo 8.0% to 10.0%, Nb 3.15%~4.15%, Fe≤5.0%, Al≤0.05%, Ti≤0.05%, and the balance is Ni and inevitable impurity elements.

[0016] Due to the significant differences in alloying elements between the two metals, the resistance to hot deformation during rolling differs, and the rolling process also differs. Generally speaking, conventional X90 pipeline steel requires two-stage rolling to develop a finer microstructure, ensuring that the steel plate has both good strength and low-temperature toughness. If the rolling temperature is too high, the steel plate remains in the recrystallization zone for too long, causing grain growth. Since the austenite flattening process in the non-recrystallization zone is not performed, the grains are ultimately too coarse and the low-temperature toughness is poor. Inconel 625, however, has poor hot workability due to its high nickel content and requires rolling in a high-temperature zone. If conventional pipeline steel is rolled in two stages, the material is difficult to deform when rolled in the temperature range of 800-900°C (the pipeline steel finishing zone), resulting in uneven deformation. Furthermore, the prolonged stay in the low-temperature sensitization zone can lead to the formation of harmful phases, which reduces the material's corrosion resistance.

[0017] In order to coordinate the conflict between the two material processes, the present invention adds higher Nb, Ti and a certain amount of V to the pipeline steel, and at the same time adjusts the rolling process, cooling process and adds a tempering process. After the rough rolling is completed, the intermediate billet is sprayed with water to accelerate the cooling, and a temperature gradient is generated in the surface substrate of the composite plate and the core composite material. At the same time, the second stage finishing rolling temperature is further increased, so that the nickel-based alloy in the core is always at a higher temperature, and the surface pipeline steel undergoes a first stage recrystallization zone rough rolling and a second stage non-recrystallization zone finishing rolling. At this time, the nickel-based alloy has good thermal deformation ability, avoids the rolling difficulties caused by the uncoordinated deformation of the two, and has good corrosion resistance. After rolling is completed, the composite steel plate is cooled by direct water cooling to reduce the temperature of the steel plate to room temperature. After the composite plate is separated, it is reheated and tempered to fully release the residual stress of the quenched structure and precipitate V in the pipeline steel, further improving the strength of the pipeline steel, thereby ensuring that the pipeline steel has a good strength and toughness match and meets the mechanical performance requirements of the transmission pipeline.

[0018] The yield strength R of the composite plate t0.5 ≥625MPa, tensile strength R m ≥695MPa, elongation A≥15%, -20℃ transverse Charpy impact Akv≥200J, -20℃ transverse DWTT shear area SA≥90%.

[0019] The composite plate interface bonding strength R S ≥450MPa, composite layer pitting corrosion rate v pit ≤3.5g / m 2 , intergranular corrosion rate v of the composite layer ig ≤0.8mm / a.

[0020] A method for manufacturing a bimetallic composite plate with an X90 grade cladding layer made of nickel-based alloy Inconel 625, specifically comprising:

[0021] 1) Prepare the raw materials. The base material X90 is continuous casting billet, and the composite material Inconel625 is metal plate. The thickness of the raw materials is designed according to the thickness ratio required by the dissimilar metals in the finished composite plate.

[0022] 2) Symmetrical billet assembly: Each composite billet consists of two X90 continuous casting billets of the same size and two nickel-based alloy Inconel625 metal plates; the billet assembly steps are as follows:

[0023] 2.1) Raw material cleaning: Use mechanical methods to remove all oxide layers from one original surface of the raw material parallel to the rolling surface to expose fresh metal.

[0024] 2.2) Spraying a release agent: Evenly spray a 1-2mm thick layer of metal oxide release agent (MgO or Al2O3) on the non-cleaned surface of the composite. Disperse the release agent in water to form a toothpaste-like consistency. Allow the water to evaporate naturally before assembling the composite. Alternatively, place the composite in a drying oven at a temperature T1 not exceeding 200°C for drying. The dried release agent must be free of defects such as cracks and holes to prevent adhesion between the two composite metals during rolling.

[0025] 2.3) Assembly welding: stack the four layers of metal in sequence, from top to bottom, in the order of X90-Inconel625-isolator-isolator-Inconel625-X90, to form a composite billet with a thickness of H; when dissimilar metals come into contact, the cleaned surfaces without oxide layer are in direct contact; the stacked raw materials are welded together along the outer edge of the contact surface to form a composite billet, and a vacuum channel is left to reduce the internal pressure of the assembled billet to 5 Pa before completing the final welding.

[0026] 3) Composite billet rolling: heat the composite billet with a thickness of H to 1230-1250℃ (T2), keep it warm for 2-4 hours (t1), and start the first stage of rough rolling after descaling. The rough rolling temperature is not less than 1180℃ (T3), and the final rolling temperature is not less than 1080℃ (T4). The thickness of the intermediate billet h is the same as the thickness of the composite plate finished product t c Ratio h / t c ≥2; After the rough rolling is completed, the intermediate billet is kept warm, the surface base material is cooled to 960-1000℃ (T5), the core composite material temperature is not less than 1000℃ (T6), and then the second stage of finishing rolling is started, and the finishing rolling temperature is not less than 930℃ (T7); immediately after rolling, it is water-cooled to 300-600℃ (T8), and the cooling rate is 10-20℃ / s (R c ), and then air-cooled to room temperature; during rolling, in order to ensure the composite effect, H / t c ≥5.

[0027] 4) The finished rolled composite plate is tempered at a tempering temperature of 500-600°C (T9). The tempering time t2 is calculated as t2=t×(1-3)min / mm+15min, where t=t c , in mm; then cut off the four sides of the cooled composite plate with welds and separate them along the isolation layer to obtain two composite plate sub-plates with a thickness of t c / 2.

[0028] Alternatively, the four sides of the composite plate with welds are cut off after finishing and separated along the separator layer to obtain two composite plate sub-plates with a thickness of t c / 2; then the sub-plate is tempered, the tempering temperature is 500 ~ 600 ℃ (T9), and the tempering time t2 is calculated according to t2 = t × (1 ~ 3) min / mm + 15min, where t = tc / 2, unit is mm.

[0029] The order of composite plate separation and post-rolling heat treatment can be adjusted according to the actual situation, and the tempering time is based on the actual thickness of the heat-treated workpiece. c or t c Just calculate it using / 2.

[0030] The main component design ideas of the present invention are as follows:

[0031] The base material X90 is an iron-based alloy containing the easily diffusible alloying element C; the composite material Inconel 625 is a nickel-based alloy to which C may or may not be added. C primarily exists in the composite material as carbides with the strengthening elements Nb, Mo, and Cr. NbC, which appears in the liquid phase, is a primary carbide. To prevent the formation of carbides such as NbC at the X90 / Inconel 625 interface due to C diffusion, which affects the interfacial bonding strength, the present invention adopts a low-C composition design. The carbon content in X90 ranges from 0.02 to 0.08%, and the carbon content in Inconel 625 does not exceed 0.08%. It is recommended that the carbon content in Inconel 625 be lower than that in X90.

[0032] Compared with the two metals. X90 has high content of Fe and Mn elements, while Inconel 625 has high content of Ni, Cr, Mo and Nb elements. Due to the rolling effect, diffusion couples can be formed at the interface, thereby forming a diffusion layer of a certain thickness to achieve metallurgical bonding, which is beneficial to improving the interface strength. Ni, Cr, Mo, and Nb diffuse into the Fe lattice, and Fe and Mn diffuse into the Ni lattice, both forming substitutional solid solutions or intermetallic compounds. These changes all occur in the solid phase, and the phase change rate is relatively slow, and the effect on the phase structure of the interface is not significant. Therefore, the main purpose of the composition design is to avoid the formation of harmful phases in Inconel 625 that are not conducive to corrosion performance. Because the raw material of the composite is Inconel 625 alloy plate, it must be fully solution treated before assembly, and the γ phase content in the matrix phase is v γ The phase composition of Inconel 625 is controlled primarily through process control rather than compositional design restrictions. To combat pitting corrosion, the pitting corrosion equivalent (PREN) of Inconel 625 must be no less than 46.4. The PREN calculation formula is Cr% + 3.3 × Mo% + 16 × N%.

[0033] The addition of high levels of Nb and Ti to pipeline steels precipitates fine Nb and Ti carbides during rolling, effectively pinning grain boundaries and inhibiting austenite grain growth during hot rolling. Furthermore, the dissolved Nb and Ti elements exist in the steel as substitutional solute atoms, which are larger than iron atoms and tend to segregate along dislocation lines, exerting a strong drag on dislocation climb. This inhibits recrystallization nucleation and strongly prevents recrystallization in pipeline steels. This allows the second-stage finish rolling to be carried out at a higher temperature range, preserving the fine recrystallized austenite grains from the first-stage rough rolling to the greatest extent possible, resulting in excellent low-temperature toughness in pipeline steels. The addition of a certain amount of V to pipeline steels refines the microstructure and grain size, improving strength and toughness, weldability, and reducing overheat sensitivity. During tempering in the 500-600°C temperature range, nanoscale V-containing precipitates gradually form. Excessive V content and the resulting large V-containing precipitates are detrimental to the steel plate's strain strengthening capacity and deteriorate the impact toughness of the weld heat-affected zone.

[0034] The reasons for the control range of the main manufacturing process parameters of the present invention are as follows:

[0035] Inconel 625 alloy has a high element content and high deformation resistance. Compared with X90, at the same deformation temperature, the deformation resistance of Inconel 625 alloy is higher than that of X90. The lower the temperature, the more significant the deformation resistance between the two. Therefore, when the billet is rolled, the rolling elongation of Inconel 625 alloy will be lower than that of X90, causing the composite plate to bend and the thickness ratio of the composite layer to the base layer to be uncontrollable. In order to avoid the rolling difficulties caused by the uncoordinated deformation of the two, a symmetrical billet is adopted, the reheating temperature of the composite billet is increased, and the final rolling temperature of the composite plate is increased. At this time, a deformation of the two metals in the rolling direction close to 1:1 can be obtained. Through high final rolling temperature and appropriate cooling rate, it is ensured that the mechanical properties of X90 and the corrosion resistance of Inconel 625 alloy meet the target requirements at the same time.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1) The rolling method can significantly improve production efficiency when producing composite plates. Compared with the explosion method, composite plates can obtain a better plate shape, which is one of the key requirements for subsequent composite plate pipe making.

[0038] 2) Through appropriate composition and process design, the TMCP+tempering process is used to produce composite plates, which have excellent corrosion resistance and mechanical properties and high production efficiency.

[0039] 3) Compared with other bonding methods, rolling bonding creates a diffusion layer of a certain width at the interface. When the diffusion layer does not contain a large amount of brittle phase, the interface bonding strength is excellent. By intentionally reducing the carbon content, the formation of brittle phase is avoided, achieving good interface bonding.

[0040] 4) Yield strength R of the composite plate t0.5 ≥625MPa, tensile strength R m ≥695MPa, elongation A≥15%, -20℃ transverse Charpy impact Akv≥200J, -20℃ transverse DWTT shear area SA≥90%, composite plate interface bonding strength R S ≥450MPa, composite layer pitting corrosion rate v pit ≤3.5g / m 2 (ASTM G48 A method), composite layer intergranular corrosion rate v ig ≤0.8mm / a (ASTM G28 A method). DETAILED DESCRIPTION

[0041] The specific embodiments of the present invention will be further described below in conjunction with examples. The following examples are used to specifically illustrate the content of the present invention. These examples are only general descriptions of the content of the present invention and do not limit the content of the present invention.

[0042] Table 1 shows the chemical composition of the base material X90 and the composite material Inconel 625 according to the embodiment of the present invention; Table 2 shows the rolling process parameters of the composite plate according to the embodiment of the present invention; Table 3 shows the tempering process parameters of the composite plate according to the embodiment of the present invention; Table 4 shows the mechanical properties and corrosion resistance of the composite plate according to the embodiment of the present invention.

[0043] Table 1 Chemical composition of the composite board according to the present invention (wt%)

[0044]

[0045] Note: * represents residual elements, the sum of which with other elements is 100%; - represents not intentionally added.

[0046] Table 2 Rolling process parameters of composite plate according to the embodiment of the present invention

[0047]

[0048] Note: RT- stands for natural drying at room temperature.

[0049] Examples 1-5 use MgO as the isolation agent with a spraying thickness of 2 mm; Examples 6-9 use Al2O3 as the isolation agent with a spraying thickness of 1.5 mm.

[0050] Table 3 Tempering process parameters of the composite plate according to the embodiment of the present invention

[0051]

[0052] Table 4 Mechanical properties and corrosion resistance of the composite plate of the embodiment of the present invention

[0053]

[0054] From the data in Tables 1, 2, and 3, it can be seen that the technical solution adopted in the present invention can produce a composite plate with a yield strength of ≥625 MPa, a tensile strength of ≥695 MPa, an elongation of ≥15%, a transverse Charpy impact of -20°C ≥200 J, a transverse DWTT shear area of ​​-20°C ≥90%, an interface bonding strength of the composite plate of ≥450 MPa, and a pitting corrosion rate of the composite layer of ≤3.5 g / m 2 , intergranular corrosion rate ≤0.8mm / a, and the composite plate has a good match of strength, toughness and corrosion resistance.

Claims

1. A bimetallic composite plate with an X90 grade cladding layer of nickel-based alloy Inconel625, characterized in that: The chemical composition thereof is calculated in percentage by weight as follows: the base material comprises C 0.02% to 0.08%, Si 0.15% to 0.25%, Mn 0.65% to 1.95%, Cr 0.05% to 0.35%, Ni 0.3% to 0.4%, Mo 0.2% to 0.35%, Cu 0.2% to 0.3%, Nb 0.06% to 0.08%, V 0.02% to 0.05%, Al≤0.05%, Ti 0.06% to 0.08%, and the balance is Fe and unavoidable impurity elements; the composite material comprises C≤0.08%, Si≤0.5%, Mn≤0.5%, Cr 20.0% to 23.0%, Mo8.0% to 10.0%, Nb 3.15%~4.15%, Fe≤5.0%, Al≤0.05%, Ti≤0.05%, and the balance is Ni and inevitable impurity elements.

2. The X90 grade bimetallic composite plate with a nickel-based alloy Inconel 625 as claimed in claim 1, characterized in that: The yield strength R of the composite plate t0.5 ≥625MPa, tensile strength R m ≥695MPa, elongation A≥15%, -20℃ transverse Charpy impact Akv≥200J, -20℃ transverse DWTT shear area SA≥90%.

3. The bimetallic composite plate with an X90 grade cladding layer of nickel-based alloy Inconel625 according to claim 1, characterized in that: The composite plate interface bonding strength R S ≥450MPa, composite layer pitting corrosion rate v pit ≤3.5g / m 2 , intergranular corrosion rate v of the composite layer ig ≤0.8mm / a.

4. A method for manufacturing a bimetallic composite plate having an X90 grade cladding layer of nickel-based alloy Inconel 625 as claimed in any one of claims 1 to 3, characterized in that: Specific content includes: Symmetrical billet assembly, each composite billet consists of two X90 continuous casting billets of the same size and two nickel-based alloy Inconel625 metal plates; The four layers of metal are stacked in sequence for assembly welding, from top to bottom: X90-Inconel625-isolating agent-isolating agent-Inconel625-X90; Composite billet rolling, heat the composite billet with thickness H to 1230-1250℃, keep it warm for 2-4 hours, take it out of the furnace and remove the scale before starting the first stage of rough rolling. The rough rolling temperature is not less than 1180℃, and the final rolling temperature is not less than 1080℃. The thickness of the intermediate billet h is the same as the thickness of the composite plate finished product t c Ratio h / t c ≥2; After the rough rolling is completed, the intermediate billet is kept warm, the surface base material is cooled to 960-1000℃, the core composite material temperature is not lower than 1000℃, and then the second stage of finishing rolling is started, and the finishing rolling temperature is not lower than 930℃; immediately after rolling, it is water-cooled to 300-600℃, the cooling rate is 10-20℃ / s, and then air-cooled to room temperature; during rolling, H / t c ≥5.

5. The method for manufacturing a bimetallic composite plate with an X90 grade cladding layer being a nickel-based alloy Inconel 625 according to claim 4, characterized in that: The finished rolled composite plate is tempered at a temperature of 500-600°C. The tempering time t2 is calculated as t2=t×(1-3)min / mm+15min, where t=t c , in mm; then cut off the four sides of the cooled composite plate with welds and separate them along the isolation layer to obtain two composite plate sub-plates with a thickness of t c / 2.

6. The method for manufacturing a bimetallic composite plate with an X90 grade cladding layer being a nickel-based alloy Inconel 625 according to claim 4, characterized in that: Cut off the four sides of the composite plate with welds after finishing and separate them along the isolation layer to obtain two composite plate sub-plates with a thickness of t c / 2; then the sub-plate is tempered at a tempering temperature of 500-600°C. The tempering time t2 is calculated as t2=t×(1-3)min / mm+15min, where t=t c / 2, unit is mm.

7. The method for manufacturing a bimetallic composite plate with an X90 grade cladding layer of nickel-based alloy Inconel625 according to claim 4, characterized in that: Before assembly, clean the raw materials and spray the isolation agent: use a mechanical method to remove all oxide layers on the original surface of the raw material parallel to the rolling surface to expose the fresh metal; evenly spray a metal oxide isolation agent with a thickness of 1 to 2 mm on the non-cleaned surface of the composite material, and assemble the composite material after the water evaporates naturally, or place the composite material in a drying furnace with a temperature not higher than 200°C for drying.

8. The method for manufacturing a bimetallic composite plate with an X90 grade cladding layer being a nickel-based alloy Inconel 625 according to claim 4 or 7, characterized in that: The release agent is MgO or Al2O3, which is dispersed in water into a toothpaste-like state.

9. The method for manufacturing a bimetallic composite plate with an X90 grade cladding layer of nickel-based alloy Inconel 625 according to claim 4, characterized in that: During the billet welding, when dissimilar metals come into contact, the cleaned surfaces without oxide layer are directly contacted; the stacked raw materials are formed into a composite billet through the outer edge of the welding contact surface, and a vacuum channel is left to reduce the internal pressure of the combined billet to 5Pa before completing the final welding.

Images