Double-metal composite plate with X70-level composite layer made of nickel-based alloy Inconel 625 and manufacturing method of double-metal composite plate

Abstract

The invention belongs to the technical field of manufacturing of high-strength corrosion-resistant structural steel, and particularly relates to an X70-grade bimetal composite plate with a composite layer made of nickel-based alloy Inconel 625, a base material is X70 pipeline steel, a composite material is made of the nickel-based alloy Inconel 625, the base material comprises the following chemical components in percentage by weight: 0.02%-0.08% of C, 0.15%-0.25% of Si, 0.65%-1.95% of Mn, 0.05%-0.35% of Cr, 0.05%-0.25% of Ni, 0.05%-0.35% of Mo, 0.1%-0.2% of Cu, 0.06%-0.08% of Nb, less than or equal to 0.05% of Al and 0.06%-0.08% of Ti, and the balance of Fe and inevitable impurities. The balance is Fe and inevitable impurity elements; the composite material comprises 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 Ni and inevitable impurity elements. The composite material has the advantages of excellent corrosion resistance and mechanical properties, and high production efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-strength corrosion-resistant structural steel manufacturing, and in particular relates to a bimetallic composite plate whose X70 grade cladding is nickel-based alloy Inconel 625. Background Art

[0002] Oil and natural gas are the energy pillars of social development. With the rapid development of the economy, my country's demand for oil and natural gas is increasing, and the easily exploitable oil and natural gas resources are becoming increasingly scarce. The exploration and development of oil and gas fields are gradually developing in areas with more severe environmental conditions, one of which is the exploitation of marine oil and gas resources. Marine oil and gas resources contain a large amount of H2S, CO2, Cl - Unlike onshore mining, offshore operations have limited space, making it difficult to install sufficient corrosive media removal equipment. Consequently, the content of corrosive media in existing pipeline steel cannot reach the permitted range. Conventional pipeline steel cannot meet the safety requirements for deep-sea oil and gas resource transportation, making pipeline perforations and cracking highly likely to occur.

[0003] For high concentrations of H2S, CO2, and Cl - Nickel-based alloys have unique advantages in corrosive media environments such as those in the pipeline. However, pure nickel-based alloy pipes are expensive, and nickel-based alloys as the corrosion-resistant part only account for a small part of the material, resulting in a huge waste of materials. Nickel-based alloy / pipeline steel composite plates combine the good corrosion resistance of the composite nickel-based alloy and the high strength and high toughness of the base pipeline steel. The bimetallic composite pipes prepared therefrom 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. In the process of producing nickel-based alloy / pipeline steel composite plates, one of the main problems is that the deformation coordination of dissimilar metals is difficult to solve, and it is difficult to achieve a comprehensive match of mechanical properties and corrosion resistance at the same time using the same production process.

[0004] Existing patent CN202410772376.8 discloses a "Method for Manufacturing X65-Grade Bimetallic Composite Plates with a Nickel-Based Alloy Cladding." This technical solution uses X65 pipeline steel as the base material and Inconel 625 nickel-based alloy as the cladding material. The pipeline steel has a Nb content of ≤0.05% and a Ti content of ≤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 steel is air-cooled and tempered. This significantly differs from the present invention's production process, which employs a high-Nb, high-Ti composition, two-stage differential rolling, and subsequent layer cooling.

[0005] Existing patent CN202410772426.2 discloses a "Method for Manufacturing X80-Grade Bimetallic Composite Plates with Nickel-Based Alloy Cladding." This technical solution uses 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. After rolling, they undergo a quenching and tempering heat treatment. This significantly differs from the present invention's production process, which employs a high-Nb, high-Ti composition, two-stage differential rolling, and subsequent layer cooling.

[0006] The existing patent CN202410118836.5 discloses “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 interfacial bonding strength. However, this method does not take into account the corrosion resistance of the Inconel625 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] Existing patent 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 according to 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] Existing patent CN201710983305.2 discloses "An 825 / X70 / 825 double-sided composite plate and its production method," and existing patent CN201710983510.9 discloses "An 825 / X70 nickel-based alloy composite plate and its production method." The corrosion-resistant layer of these two technical solutions is 825 alloy, which contains no less than 22% iron. Its chemical properties are closer to those of the substrate, making it easier to resolve deformation inconsistencies. The final rolling temperature is 760-830°C. The present invention uses a 625 nickel-based alloy with an iron content of no more than 5%, and employs a two-stage differential temperature rolling followed by layer cooling, which is significantly different.

[0009] Existing patent CN201710453074.4 discloses a "Method for Preparing Large-Scale, Thin-Layered Nickel-Based Alloy / Pipeline Steel Composite Plate." This technical solution uses explosive welding to prepare the composite billet, followed by asynchronous rolling with a speed ratio of 1.05 to 1.30 to overcome the deformation disharmony between the two metals to produce the desired composite plate. The present invention uses a metallurgical composite method to form the billet, followed by synchronous rolling to produce the desired composite plate, which is significantly different.

[0010] The existing patent CN202410909051.X discloses "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 production process of the present invention, which adopts a two-stage surface substrate rolling temperature of 960-1000°C, a core composite material rolling temperature of not less than 1000°C, a two-stage finishing rolling temperature of not less than 930°C, and post-rolling tempering.

[0011] The existing patent CN201811017043.5 discloses "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, and the second-stage surface substrate rolling temperature used in the present invention is 960-1000°C, 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 has significant differences.

[0012] In summary, in order to solve the problem of uncoordinated deformation, some existing technologies use asynchronous rolling technology, while others use heat treatment processes or asymmetric billet assembly processes to further optimize the performance of composite plates. Asynchronous rolling technology has strict requirements on rolling mill capacity, and the use of heat treatment processes or asymmetric billet assembly processes will lead to reduced production efficiency and increased production costs. To solve these problems, by comprehensively optimizing the components of X70 and Inconel 625 and then matching them with a suitable rolling process, a bimetallic composite plate for oil and gas pipelines with a yield strength not lower than X70 and excellent corrosion resistance can be obtained. Summary of the Invention

[0013] The technical problem to be solved by the present invention is to provide a bimetallic composite plate with an X70 grade cladding layer of nickel-based alloy Inconel 625, which has excellent corrosion resistance and mechanical properties and high production efficiency.

[0014] To achieve the above objectives, the present invention adopts the following technical solutions:

[0015] A bimetallic composite plate with an X70 grade cladding layer of nickel-based alloy Inconel 625, wherein the base material is X70 pipeline steel and the cladding material is Inconel 625 nickel-based alloy, and the chemical composition is calculated by weight percentage:

[0016] Base material: 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 0.05% to 0.25%, Mo 0.05% to 0.35%, Cu 0.1% to 0.2%, Nb 0.06% to 0.08%, Al ≤ 0.05%, Ti 0.06% to 0.08%, the balance is Fe and unavoidable impurity elements;

[0017] Composite material: 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≤0.05%, Ti≤0.05%, and the balance is Ni and unavoidable impurity elements.

[0018] The pitting corrosion resistance equivalent PREN of the composite Inconel 625 nickel-based alloy is not less than 46.4.

[0019] Content of solid solution γ phase in composite Inconel 625 nickel-based alloy plate v γ Not less than 95%.

[0020] A bimetallic composite plate with an X70 grade cladding layer of nickel-based alloy Inconel 625 Performance indicators: Yield strength R t0.5 ≥485MPa, tensile strength R m ≥570MPa, elongation A≥15%, -20℃ transverse Charpy impact Akv≥220J, -20℃ transverse DWTT shear area SA≥90%, composite plate interface bonding strength R S ≥400MPa, composite layer pitting corrosion rate v pit ≤3.5g / m 2 , intergranular corrosion rate v of the composite layer ig ≤0.8mm / a.

[0021] A method for producing a bimetallic composite plate having an X70 grade cladding layer made of nickel-based alloy Inconel 625, the production steps are as follows:

[0022] 1) Raw materials: The base material is X70 pipeline steel continuous casting billet, and the composite material is Inconel 625 nickel-based alloy plate;

[0023] 2) Symmetrical assembly: The composite blank consists of two base materials and two composite materials of the same size. The assembly steps are as follows:

[0024] ① Cleaning: Remove the oxide layer on one surface of the substrate and composite material to expose the metal body;

[0025] ② Apply release agent: Apply release agent with a thickness of 1 to 2 mm evenly on the non-cleaned surface of the composite material;

[0026] ③ Assembly welding: The cleaned surfaces without oxide layer are in direct contact. The composite billet is arranged from top to bottom in the order of substrate-composite-isolating agent-isolating agent-composite-substrate. The interior of the assembled billet is vacuumed to 4-6 Pa.

[0027] 3) Controlled rolling and cooling of composite plate: heat the composite billet to 1230-1250℃, keep it warm for 2-4 hours, take it out of the furnace and remove the scale, then start the first stage of rough rolling, the starting temperature of rough rolling is not less than 1180℃, the final rolling temperature is not less than 1080℃, after the end of rough rolling, spray water on the intermediate billet to accelerate cooling, the surface base material temperature is reduced to 960-1000℃, the core composite material temperature is not less than 1000℃, then start the second stage of finishing rolling, the finishing rolling temperature is not less than 930℃, immediately after rolling, water-cooled to 550-600℃, the cooling rate is 10-20℃ / s, and then air-cooled to room temperature;

[0028] 4) Composite board separation.

[0029] Step 2) ② Release agent application process: Metal oxide MgO or Al2O3 is dispersed in water into a toothpaste-like form and applied to the composite material. The water evaporates naturally, or the composite material is placed in a drying oven at a temperature not higher than 200°C for drying.

[0030] Step 3) The thickness H of the composite blank and the thickness t of the composite plate c Ratio H / t c ≥5; intermediate billet thickness h and composite plate thickness t c Ratio h / t c ≥2.

[0031] Compared with the existing technology, the beneficial effects of the present invention are:

[0032] The composite plate of the present invention has a yield strength not lower than X70 and excellent corrosion resistance and is a bimetallic composite plate for oil and gas transmission pipelines.

[0033] 1) The rolling method for producing composite plates can significantly improve production efficiency and obtain a good plate shape. The flatness of the finished composite plate is ≤3mm / 2m, which is one of the key requirements for subsequent composite plate pipe making.

[0034] 2) Through appropriate composition and process design, a controlled rolling and controlled cooling process is used to produce composite plates. High levels of Nb and Ti are added to the pipeline steel. After rough rolling, the intermediate billet is sprayed with water for accelerated cooling, creating a temperature gradient between the surface of the composite plate's substrate and the core of the composite. The second-stage finishing temperature is further increased, keeping the nickel-based alloy in the core at a consistently high temperature. The surface pipeline steel undergoes rough rolling in the recrystallization zone in the first stage and finishing rolling in the non-recrystallization zone in the second stage. This allows the nickel-based alloy to exhibit excellent thermal deformation capabilities, avoiding rolling difficulties caused by uncoordinated deformation between the two. The X70 pipeline steel has a grain size rating of no less than grade 11, and the Inconel 625 nickel-based alloy has a grain size rating of no less than grade 6.5. The composite plates exhibit both excellent corrosion resistance and mechanical properties.

[0035] 3) Compared with other composite methods, rolling composite has a certain width of diffusion layer at the interface. When there is no large amount of brittle phase in the diffusion layer, the interface bonding strength is excellent (composite plate interface bonding strength R S ≥400MPa). By intentionally reducing the C content, the formation of brittle phases is avoided and good interface bonding effect is achieved.

[0036] 4) Yield strength R of the composite plate t0.5 ≥485MPa, tensile strength R m ≥570MPa, elongation A≥15%, -20℃ transverse Charpy impact Akv≥220J, -20℃ transverse DWTT shear area SA≥90%, 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

[0037] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein in the specification of the application are for the purpose of describing specific embodiments only and are not intended to limit this application. Mentioning "embodiments" herein means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention.

[0038] A bimetallic composite plate with an X70 grade cladding layer of nickel-based alloy Inconel 625, wherein the base material is X70 pipeline steel and the cladding material is Inconel 625 nickel-based alloy, and the chemical composition is calculated by weight percentage:

[0039] Base material: 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 0.05% to 0.25%, Mo 0.05% to 0.35%, Cu 0.1% to 0.2%, Nb 0.06% to 0.08%, Al ≤ 0.05%, Ti 0.06% to 0.08%, the balance is Fe and unavoidable impurity elements;

[0040] Composite material: 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≤0.05%, Ti≤0.05%, and the balance is Ni and unavoidable impurity elements.

[0041] The pitting corrosion resistance equivalent PREN of the composite Inconel 625 nickel-based alloy is not less than 46.4.

[0042] Content of solid solution γ phase in composite Inconel 625 nickel-based alloy plate v γ Not less than 95%.

[0043] A method for producing a bimetallic composite plate having an X70 grade cladding layer made of nickel-based alloy Inconel 625, the production steps are as follows:

[0044] 1) Raw materials: The base material is X70 pipeline steel continuous casting billet, and the composite material is Inconel 625 nickel-based alloy plate;

[0045] 2) Symmetrical assembly: The composite blank consists of two base materials and two composite materials of the same size; the composite blank has a thickness of H. The assembly steps are as follows:

[0046] ① Cleaning: Remove the oxide layer on one surface of the substrate and composite material to expose the metal body;

[0047] ② Apply release agent: Apply release agent with a thickness of 1 to 2 mm evenly on the non-cleaned surface of the composite material;

[0048] ③ Assembly welding: The cleaned surfaces without oxide layer are in direct contact. The composite billet is arranged from top to bottom in the order of substrate-composite-release agent-release agent-composite-substrate. The interior of the assembled billet is vacuumed to 4-6 Pa.

[0049] 3) Controlled rolling and controlled cooling of composite plate: the composite billet is heated to a temperature of T2: 1230-1250°C, and the holding time is t1: 2-4 hours. After the billet is taken out of the furnace and descaled, the first stage of rough rolling begins. The rough rolling start temperature T3 is not less than 1180°C, and the final rolling temperature T4 is not less than 1080°C. After the rough rolling is completed, the intermediate billet is sprayed with water to accelerate cooling. The surface substrate cooling temperature T5 is 960-1000°C, and the core composite material temperature T6 is not less than 1000°C. Then the second stage of finishing rolling begins, and the finishing rolling temperature T7 is not less than 930°C. After rolling, water cooling is immediately carried out, and the temperature after water cooling is T8: 550-600°C. The cooling rate R c : 10~20℃ / s, then air-cool to room temperature; composite plate thickness t c ;

[0050] 4) Composite plate separation: After cooling, cut off the four sides of the composite plate with welds and separate them along the separator to obtain two composite plate sub-plates with a thickness of t c / 2.

[0051] Step 2) ② Release Agent Application Process: Disperse the metal oxide MgO or Al2O3 in water to form a toothpaste-like coating and apply it to the composite. Allow the water to evaporate naturally, or dry the composite in a drying oven at a temperature T1 no higher than 200°C. The dried release agent must be free of defects such as cracks and holes to prevent adhesion between the two composite materials during rolling.

[0052] Step 3) The thickness H of the composite blank and the thickness t of the composite plate c Ratio H / t c ≥5; intermediate billet thickness h and composite plate thickness t c Ratio h / t c ≥2.

[0053] Chemical composition and process description of the present invention:

[0054] The base material, X70 pipeline steel, is an iron-based alloy containing the easily diffusible alloying element carbon. The composite material, Inconel 625, is a nickel-based alloy. Within the composite, carbon primarily forms carbides with the strengthening elements Nb, Mo, and Cr. NbC, a primary carbide, can form even in the liquid phase. To prevent the formation of carbides like NbC at the X70 / Inconel 625 interface due to carbon diffusion, which could compromise the interfacial bond strength, the present invention employs a low-carbon design. The carbon content in the X70 pipeline steel ranges from 0.02% to 0.08%, while the carbon content in the Inconel 625 nickel-based alloy does not exceed 0.08%. It is recommended that the carbon content in Inconel 625 be lower than that in the X70 pipeline steel.

[0055] The base material X70 pipeline steel has high content of Fe and Mn elements, and 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, all of which form 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 composition design is to avoid the formation of harmful phases in Inconel 625 that are not conducive to corrosion performance. The content of γ phase in the solid solution phase in the composite Inconel 625 nickel-based alloy plate is v γ Not less than 95%, especially no carbides or carbonitrides are allowed to form on the grain boundaries.

[0056] The addition of high levels of Nb and Ti to the base X70 pipeline steel allows for the precipitation of 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 suppresses recrystallization nucleation in the pipeline steel and has a strong inhibitory effect on recrystallization. This allows the second stage of finish rolling to be carried out at a higher temperature range, preserving the fine recrystallized austenite grains from the first stage of rough rolling to the greatest extent possible, resulting in the pipeline steel's excellent low-temperature toughness.

[0057] The composite Inconel 625 alloy has a high element content and high deformation resistance. Compared with X70, at the same deformation temperature, the deformation resistance of Inconel 625 alloy is higher than that of X70. 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 X70, causing the composite plate to warp and the thickness ratio of the composite layer to the substrate 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 X70 and the corrosion resistance of Inconel 625 alloy meet the target requirements at the same time.

[0058] Due to the significant differences in alloying elements between the two metals, the resistance to hot deformation during rolling differs, requiring different rolling processes. Conventional X70 pipeline steel generally requires two-stage rolling to develop a finer microstructure, ensuring 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, leading to grain growth. Without the austenite flattening process in the non-recrystallization zone, the grains ultimately become coarse and the low-temperature toughness is poor. Inconel 625, however, has poor hot workability due to its high nickel content, requiring rolling in a high-temperature zone. Conventional two-stage rolling of pipeline steel makes it difficult to deform the material during rolling in the 800-900°C (finishing zone for pipeline steel), resulting in uneven deformation. Furthermore, prolonged exposure to the low-temperature sensitization zone can lead to the formation of harmful phases, reducing the material's corrosion resistance.

[0059] To balance the conflicting processes between the two materials, this method incorporates higher levels of Nb and Ti into the pipeline steel. The rolling process is also adjusted, with water spraying accelerating cooling of the intermediate billet after rough rolling. This creates a temperature gradient between the surface of the composite plate's substrate and the core of the composite. Furthermore, the second-stage finishing rolling temperature is further increased, keeping the nickel-based alloy in the core at a consistently high temperature. The surface pipeline steel undergoes rough rolling in the recrystallization zone in the first stage and finishing rolling in the non-recrystallization zone in the second stage. This allows the nickel-based alloy to exhibit excellent thermal deformation resistance, avoiding rolling difficulties caused by the deformation mismatch between the two, while also providing excellent corrosion resistance. The pipeline steel, on the other hand, possesses a good balance of strength and toughness, meeting the mechanical property requirements of the transmission pipeline.

[0060] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0061] Example:

[0062] Table 1 shows the chemical composition of the substrate X70 and the composite Inconel 625 according to an embodiment of the present invention; Table 2 shows the rolling process parameters of the composite plate according to an embodiment of the present invention; Table 3 shows the mechanical properties and corrosion resistance of the composite plate according to an embodiment of the present invention.

[0063] Table 1: Chemical composition (wt%) of the composite board of the embodiment

[0064]

[0065]

[0066] Note: * represents residual elements, the sum of which with other elements is 100%; - represents not intentionally added.

[0067] Table 2: Rolling process parameters of the composite plate of the embodiment

[0068]

[0069]

[0070] Note: RT stands for natural drying at room temperature.

[0071] Table 3: Mechanical properties and corrosion resistance of composite plates of the examples

[0072]

[0073] Note: R t0.5 Represents the yield strength, R m Represents tensile strength, R s represents the interface bonding strength, A represents the elongation after fracture, Akv represents the impact energy, SA represents the DWTT shear area, v pit represents the pitting corrosion rate of the composite layer, v ig Represents the intergranular corrosion rate of the composite layer.

[0074] From the data in Tables 1, 2, and 3, it can be seen that the technical solution adopted in the present invention has a composite plate with a yield strength of ≥485 MPa, a tensile strength of ≥570 MPa, an elongation of ≥15%, a transverse Charpy impact of -20°C ≥220 J, a transverse DWTT shear area of ​​-20°C ≥90%, a composite plate interface bonding strength of ≥400 MPa, and a composite layer pitting corrosion rate 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.

[0075] The present invention provides a novel catalyst rich in H2S, CO2, Cl through reasonable component design and optimized preparation process matching. - It provides a new technical solution for the selection of line pipes for transporting oil and gas resources in corrosive media.

[0076] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and basic spirit of the invention, and the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A bimetallic composite plate with an X70 grade cladding layer of nickel-based alloy Inconel 625, characterized in that: The base material is X70 pipeline steel and the composite material is Inconel 625 nickel-based alloy. The chemical composition is calculated by weight percentage: Base material: 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 0.05% to 0.25%, Mo 0.05% to 0.35%, Cu 0.1% to 0.2%, Nb 0.06% to 0.08%, Al ≤ 0.05%, Ti 0.06% to 0.08%, the balance is Fe and unavoidable impurity elements; Composite material: C≤0.08%, Si≤0.5%, Mn≤0.5%, Cr 20.0%~23.0%, Mo 8.0%~10.0%, Nb3.15%~4.15%, Fe≤5.0%, Al≤0.05%, Ti≤0.05%, and the balance is Ni and unavoidable impurity elements. The pitting corrosion resistance equivalent PREN of the composite Inconel 625 nickel-based alloy is not less than 46.

4. Content of solid solution γ phase in composite Inconel 625 nickel-based alloy plate v γ Not less than 95%. A bimetallic composite plate with an X70 grade cladding layer of nickel-based alloy Inconel 625 Performance indicators: Yield strength R t0.5 ≥485MPa, tensile strength R m ≥570MPa, elongation A≥15%, -20℃ transverse Charpy impact Akv≥220J, -20℃ transverse DWTT shear area SA≥90%, composite plate interface bonding strength R S ≥400MPa, composite layer pitting corrosion rate v pit ≤3.5g / m 2 , intergranular corrosion rate v of the composite layer ig ≤0.8mm / a.

2. The method for producing a bimetallic composite plate with an X70 grade cladding layer of nickel-based alloy Inconel 625 according to claim 1, characterized in that: The production steps are as follows: 1) Raw materials: The base material is X70 pipeline steel continuous casting billet, and the composite material is Inconel 625 nickel-based alloy plate; 2) Symmetrical assembly: The composite blank consists of two base materials and two composite materials of the same size. The assembly steps are as follows: ① Cleaning: Remove the oxide layer on one surface of the substrate and composite material to expose the metal body; ② Apply release agent: Apply release agent with a thickness of 1 to 2 mm evenly on the non-cleaned surface of the composite material; ③ Assembly welding: The cleaned surfaces without oxide layer are in direct contact. The composite billet is arranged from top to bottom in the order of substrate-composite-isolating agent-isolating agent-composite-substrate. The interior of the assembled billet is vacuumed to 4-6 Pa. 3) Controlled rolling and cooling of composite plate: heat the composite billet to 1230-1250℃, keep it warm for 2-4 hours, take it out of the furnace and remove the scale, then start the first stage of rough rolling, the starting temperature of rough rolling is not less than 1180℃, the final rolling temperature is not less than 1080℃, after the end of rough rolling, spray water on the intermediate billet to accelerate cooling, the surface base material temperature is reduced to 960-1000℃, the core composite material temperature is not less than 1000℃, then start the second stage of finishing rolling, the finishing rolling temperature is not less than 930℃, immediately after rolling, water-cooled to 550-600℃, the cooling rate is 10-20℃ / s, and then air-cooled to room temperature; 4) Composite board separation.

3. The method for producing a bimetallic composite plate with an X70 grade cladding layer of nickel-based alloy Inconel 625 according to claim 2, characterized in that: Step 2) ② Release agent application process: Metal oxide MgO or Al2O3 is dispersed in water into a toothpaste-like form and applied to the composite material. The water evaporates naturally, or the composite material is placed in a drying oven at a temperature not higher than 200°C for drying.

4. The method for producing a bimetallic composite plate with an X70 grade cladding layer of nickel-based alloy Inconel 625 according to claim 2, characterized in that: Step 3) The thickness H of the composite blank and the thickness t of the composite plate c Ratio H / t c ≥5; intermediate billet thickness h and composite plate thickness t c Ratio h / t c ≥2.

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