A pipeline steel for supercritical carbon dioxide transport pipelines and a method of manufacturing the same

Abstract

The present application relates to pipeline steel preparation technical field, specifically to a kind of supercritical carbon dioxide conveying pipeline with pipeline steel and its manufacturing method.The supercritical carbon dioxide conveying pipeline with pipeline steel includes the following mass percentage of chemical components: C:0.03%~0.07%, Mn:1.20%~1.50%, S≤0.001%, P≤0.008%, Al≤0.06%, Si:0.2%~0.3%, Cr:0.5%~1.0%, Nb:0.03%~0.05%, Ti:0.01%~0.03%, Ni:0~0.15%, N:0.004%~0.008%, Al / N≥2.5%, the balance is Fe.The present application can improve corrosion resistance and toughness, effectively avoid austenite grain uneven growth, inhibit carbide precipitation, improve the strength, toughness and creep performance of steel, and the mechanical properties and carbon dioxide corrosion resistance performance match well, and the corrosion resistance is more than 10 times of ordinary pipeline steel.

Description

Technical Field

[0001] This invention belongs to the field of pipeline steel preparation technology, specifically relating to a pipeline steel for supercritical carbon dioxide transmission pipelines and its manufacturing method. Background Technology

[0002] Carbon emissions have become a major concern, and carbon dioxide capture, utilization, and storage (CVS) are effective ways to address this issue. Currently, carbon dioxide enhanced oil recovery (CEOR) technology is being widely applied to improve oil recovery rates while simultaneously storing carbon dioxide. Using supercritical carbon dioxide pipelines for large-scale, long-distance carbon dioxide transport is currently the most economical and feasible method.

[0003] Currently, carbon dioxide transmission pipelines are often made of ordinary pipeline steel. This steel has low strength and small diameter, and since the medium is gaseous, it is insufficient to meet the requirements for transporting supercritical carbon dioxide in terms of resistance to carbon dioxide corrosion, low-temperature fracture toughness, and resistance to aging degradation. To meet the needs of supercritical carbon dioxide pipeline projects, there is an urgent need to develop high-strength, large-diameter, high-capacity pipeline steel for supercritical carbon dioxide pipeline projects. This would improve the pipeline's resistance to carbon dioxide corrosion and low-temperature brittle fracture resistance, while simultaneously increasing the pipeline's transport capacity and reducing material and construction costs. Patent CN103334055A discloses a pipeline steel resistant to carbon dioxide and hydrogen sulfide corrosion and its production method. The pipeline steel produced by this process has good resistance to carbon dioxide corrosion, but its strength is low, and its low-temperature crack initiation and crack arrest toughness cannot meet the requirements of pipelines transporting supercritical carbon dioxide. Patent CN107904496A discloses a pipeline steel resistant to carbon dioxide corrosion and its manufacturing method. However, the pipeline steel produced by this process can only meet the crack arrest requirement at -30℃, but cannot meet the requirement of preventing crack initiation at -70℃. Moreover, its carbon dioxide corrosion rate can reach up to 2.3 mm / a, which cannot meet the design safety requirements of pipelines transporting supercritical carbon dioxide. Patent CN118186302A discloses a production method of X65MC supercritical carbon dioxide transport pipeline steel. Its strength is low, and its supercritical carbon dioxide corrosion rate can reach up to about 1 mm / a, but it cannot meet the design safety requirements of pipelines transporting large-capacity supercritical carbon dioxide. Summary of the Invention

[0004] In order to overcome the defects of the prior art, the present invention discloses a pipeline steel for supercritical carbon dioxide transmission pipelines and its manufacturing method, so as to solve the problems of carbon dioxide corrosion resistance and low-temperature toughness matching difficulties in the prior art for large-capacity supercritical carbon dioxide transmission pipelines.

[0005] This invention is achieved through the following technical solution: This invention discloses a pipeline steel for supercritical carbon dioxide transmission pipelines, wherein the pipeline steel comprises, by mass percentage: C: 0.03%–0.07%, Mn: 1.20%–1.50%, S≤0.001%, P≤0.008%, Al≤0.06%, Si: 0.2%–0.3%, Cr: 0.5%–1.0%, Nb: 0.03%–0.05%, Ti: 0.01%–0.03%, Ni: 0–0.15%, N: 0.004%–0.008%, Al / N≥2.5, with the balance being Fe.

[0006] Optionally, the pipeline steel has a tensile strength of 620MPa to 720MPa, a yield strength of 500MPa to 620MPa, a low-temperature crack initiation toughness of not less than 200J at -60℃, a crack arrest toughness of not less than 300J at -40℃, a DWTT shear area of ​​not less than 85% at -30℃, and a corrosion rate of not more than 0.1mm / a.

[0007] This invention also discloses a method for manufacturing pipeline steel for supercritical carbon dioxide transmission pipelines, the method comprising: The pipeline steel billet is heated, kept at a constant temperature, rough rolled, and finish rolled to obtain a hot-rolled plate; The pipeline steel is obtained by cooling the hot-rolled plate.

[0008] Optionally, the heating temperature is 1180℃~1200℃.

[0009] Optionally, the heat preservation time is 2.5h to 3.0h.

[0010] Optionally, in the rough rolling, the initial rolling temperature is 1080℃~1100℃, and the final rolling temperature is 970℃~1000℃.

[0011] Optionally, in the finishing rolling process, the initial rolling temperature is 900℃~950℃, and the final rolling temperature is 780℃~820℃.

[0012] Optionally, the cooling temperature is 450℃~580℃.

[0013] Optionally, the cooling rate is 8°C / s to 15°C / s.

[0014] Optionally, the cooling method is water cooling.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses pipeline steel for supercritical carbon dioxide transportation pipelines. By adding an appropriate amount of Cr element to the steel and combining controlled rolling and cooling, the proportion of high-energy, large-angle grain boundaries is reduced, thereby lowering the corrosion rate. By reducing the content of S, P, and Mn, center segregation is reduced, and the aggregation of P and S elements at grain boundaries is decreased, further improving corrosion resistance and toughness. By controlling the N content and Al / N ratio, uneven growth of austenite grains can be effectively avoided, carbide precipitation is inhibited, and the strength, toughness, and creep performance of the steel are improved. The pipeline steel for supercritical carbon dioxide transportation pipelines produced according to this invention has a good match between mechanical properties and carbon dioxide corrosion resistance. The tensile strength is 620MPa~720MPa, the yield strength is 500MPa~620MPa, the low-temperature crack initiation toughness at -60℃ is not less than 200J, the crack arrest toughness at -40℃ is not less than 300J, and the shear area at DWTT~30℃ is not less than 85%. In a supercritical carbon dioxide environment, the corrosion rate is not greater than 0.1mm / a, and the corrosion resistance is more than 10 times that of ordinary pipeline steel. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a metallographic image of the pipeline steel used in the supercritical carbon dioxide transmission pipeline of the present invention. Detailed Implementation

[0018] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0019] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0020] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0021] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0022] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0023] The invention will now be described in further detail below, taking into account the functions of several key chemical components: Carbon (C) exists primarily in steel through solid solution to improve the hardenability of austenite and produce a bainitic-ferrite microstructure. However, excessive C content should be avoided, as it can easily form C-rich MA components in the steel, deteriorating the material's toughness. Furthermore, high C content can also affect its weldability. Therefore, the C content of the pipeline steel in this invention is controlled within the range of 0.03% to 0.07%.

[0024] Cr: Chromium is a supercritical component of this invention. Cr is the most important alloying element in steel used for pipeline transportation. It is one of the most functional and widely used alloying elements in steel. Chromium significantly improves the corrosion resistance and oxidation resistance of steel. Adding a certain amount of chromium to steel can improve its mechanical, physical, and chemical properties, and help improve wear resistance and maintain high-temperature strength. Simultaneously, Cr is also an alloying element that provides hardenability, promoting the formation of acicular ferrite during cooling. This invention reduces the proportion of high-energy, large-angle grain boundaries and decreases the corrosion rate by adding an appropriate amount of Cr to steel, combined with controlled rolling and controlled cooling. The Cr content in this invention is generally 0.5%–1.0%.

[0025] Mn: Manganese is a key element for improving the strength of pipeline steel. The addition of Mn can significantly reduce the phase transformation temperature, refine the grain size, and improve the toughness of the steel. In this invention, the Mn content ranges from 1.20% to 1.50%.

[0026] Phosphorus (P) is an impurity element in pipeline steel. Excessive P content can negatively impact the steel's performance, such as causing cold brittleness at low temperatures and deteriorating its weldability. Especially since the steel plates of this invention are primarily used in extremely low temperature environments of -40°C and below, the P content must be strictly controlled. The P content range in this invention is: P ≤ 0.008%.

[0027] S: Sulfur combines with Mn in steel to form MnS, reducing the effective Mn content and simultaneously decreasing the steel's resistance to HIC and SCC. Therefore, the lower the S content in steel, the better. In this invention, the S content range is: S ≤ 0.001%.

[0028] This invention improves corrosion resistance and toughness by reducing the content of S, P, and Mn, thereby reducing central segregation and minimizing the accumulation of P and S elements at grain boundaries.

[0029] Al: Aluminum is a commonly used deoxidizer in steel. Adding a small amount of aluminum to steel can refine the grains and improve impact toughness. However, in ferritic steel, a high Al content can reduce its high-temperature strength and toughness, and cause difficulties in smelting and casting. Therefore, the Al content in this invention is generally Al≤0.06%.

[0030] Nitrogen (N) is a commonly used alloying element that can dissolve in austenite (a crystal structure of steel). By adjusting the nitrogen content, the microstructure and properties of steel can be affected. The N content in this invention is generally 0.004% to 0.008%.

[0031] This invention effectively avoids uneven growth of austenite grains and inhibits carbide precipitation by controlling the addition of nitrogen and aluminum, thereby improving the strength, toughness, and creep properties of steel. Therefore, the controlled ratio of Al to N in this invention is: Al / N ≥ 2.5.

[0032] Si: Silicon in pipeline steel is generally a steelmaking residue, mainly playing a role in solid solution strengthening. However, for high-grade pipeline steel, in order to ensure the low-temperature toughness of the weld heat-affected zone, the silicon content in the steel should be strictly controlled to reduce the silicate inclusion content and avoid excessive formation of MA components. In this invention, the Si content is generally 0.2% to 0.3%.

[0033] Niobium (Nb) can significantly increase the austenite recrystallization temperature of steel, expand the non-recrystallized region, facilitate high-temperature controlled rolling, and reduce mill load. Simultaneously, niobium can inhibit austenite grain growth, exhibiting significant grain refinement and precipitation strengthening effects. However, Nb is a precious alloy, and increasing its content significantly increases alloy costs. Furthermore, in high-strength pipeline steel, excessive niobium addition promotes the formation of austenite islands (MA islands), reducing the toughness of the weld heat-affected zone. In this invention, the Nb content is generally 0.03%–0.05%.

[0034] Ti: Similar to niobium in steel, titanium has strong grain refinement and precipitation strengthening effects. Trace amounts of titanium can also combine with carbon and oxygen at high temperatures to form high-temperature refractory precipitates, which helps to inhibit austenite grain growth in the weld heat-affected zone and significantly improves the toughness of the weld heat-affected zone. In this invention, the Ti content is generally 0.01% to 0.03%.

[0035] Ni: Nickel can effectively improve the hardenability of steel, has a certain solid solution strengthening effect, and can also significantly improve the low-temperature toughness of steel. However, like molybdenum, nickel is a precious metal, which can lead to a significant increase in the manufacturing cost of steel. In this invention, the Ni content is generally 0-0.15%.

[0036] This invention also discloses a method for manufacturing pipeline steel for supercritical carbon dioxide transmission pipelines: First, the pipeline steel billet is heated to a suitable temperature for subsequent hot working. This step is usually carried out in a furnace to give the pipeline steel billet sufficient plasticity for subsequent rolling. In this invention, the heating temperature is 1180℃~1200℃.

[0037] The heated pipeline steel billet needs to be kept in an insulated environment for a period of time to ensure uniform heating. The purpose of insulation is to prevent uneven cooling of the billet during heating, which would affect the rolling quality. In this invention, the insulation time is 2.5h to 3.0h. The heated and held-temperature pipeline steel billet is fed into a rolling mill for rough rolling. The main purpose of rough rolling is to reduce the thickness of the pipeline steel billet to near the thickness of the final product, while preparing for finish rolling. In the rough rolling of this invention, the initial rolling temperature is 1080℃~1100℃, and the final rolling temperature is 970℃~1000℃.

[0038] After rough rolling, the pipeline steel billet undergoes finish rolling. Finish rolling is carried out under more stringent control conditions to further adjust the thickness and surface quality of the steel plate to achieve the required dimensions and surface finish. In the finish rolling of this invention, the initial rolling temperature is 900℃~950℃, and the final rolling temperature is 780℃~820℃.

[0039] After finishing rolling, the hot-rolled plate is cooled to a certain temperature. In this invention, the cooling temperature is 450℃~580℃, the cooling rate is 8℃ / s~15℃ / s, and the cooling method is water cooling. The thermal conductivity of water is utilized to rapidly remove the residual heat from the steel plate. Water cooling effectively reduces the temperature of the steel plate, achieving rapid cooling. This rapid cooling method fully utilizes the cooling effect of water, refines the phase transformation structure, and improves the drop hammer impact resistance and Charpy impact resistance of the steel plate.

[0040] After the above steps, the final pipeline steel product is obtained. Its production process is simple, requiring no upgrades to existing metallurgical equipment, rolling mills, and cooling equipment, nor the addition of new equipment; it can be directly industrialized. This invention can significantly improve the strength, low-temperature crack initiation and arrest toughness of pipeline steel, and greatly enhance its resistance to carbon dioxide corrosion, resulting in substantial economic benefits.

[0041] The X70MC / L485MC pipeline steel produced according to this invention exhibits excellent mechanical properties and resistance to carbon dioxide corrosion: tensile strength of 620MPa~720MPa, yield strength of 500MPa~620MPa, low-temperature crack initiation toughness of not less than 200J at -60℃, crack arrest toughness of not less than 300J at -40℃, and DWTT shear area of ​​not less than 85% at -30℃. In a supercritical carbon dioxide environment, the corrosion rate is not greater than 0.1mm / a, and its corrosion resistance is more than 10 times that of ordinary pipeline steel.

[0042] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0043] Example 1 Pipeline steel composition: C: 0.03%, Mn: 1.20%, S: 0.001%, P: 0.008%, Al: 0.06%, Si: 0.2%, Cr: 0.5%, Nb: 0.03%, Ti: 0.01%, Ni: 0%, N: 0.004%, Al / N: 15, balance Fe.

[0044] Manufacturing process: The pipeline steel billet obtained from the above materials is heated to approximately 1180℃ and held at that temperature for 3.0 hours. It is then rough-rolled at 1080℃ with a finishing temperature of 970℃, followed by finish rolling at 900℃ with a finishing temperature of 780℃. The total reduction rate during rough rolling is not less than 65%, and the total reduction rate during finish rolling is not less than 70%, yielding a hot-rolled plate. The hot-rolled plate is then cooled to 450℃ to obtain pipeline steel.

[0045] Performance characteristics: The pipeline steel prepared in this embodiment has a tensile strength of 620MPa~720MPa, a yield strength of 500MPa~620MPa, a low-temperature crack initiation toughness of not less than 200J at -60℃, a crack arrest toughness of not less than 300J at -40℃, a shear area of ​​not less than 85% at DWTT~30℃, and a corrosion rate of not more than 0.1mm / a in a supercritical carbon dioxide environment.

[0046] Example 2 Pipeline steel composition: C: 0.07%, Mn: 1.50%, S: 0.0007%, P: 0.004%, Al: 0.03%, Si: 0.3%, Cr: 1.0%, Nb: 0.05%, Ti: 0.03%, Ni: 0.15%, N: 0.008%, Al / N: 3.75, balance Fe.

[0047] Manufacturing process: The pipeline steel billet obtained from the above materials is heated to approximately 1200℃ and held at that temperature for 2.5 hours. It is then rough-rolled at 1100℃ with a finishing temperature of 1000℃, followed by finish rolling at 950℃ with a finishing temperature of 820℃. The total reduction rate during rough rolling is not less than 65%, and the total reduction rate during finish rolling is not less than 70%, resulting in a hot-rolled plate. The hot-rolled plate is then cooled to 580℃ to obtain pipeline steel.

[0048] Performance characteristics: The pipeline steel prepared in this embodiment has a tensile strength of 620MPa~720MPa, a yield strength of 500MPa~620MPa, a low-temperature crack initiation toughness of not less than 200J at -60℃, a crack arrest toughness of not less than 300J at -40℃, a shear area of ​​not less than 85% at DWTT~30℃, and a corrosion rate of not more than 0.1mm / a in a supercritical carbon dioxide environment.

[0049] Example 3: Pipeline steel composition: C: 0.05%, Mn: 1.40%, S: 0.0008%, P: 0.006%, Al: 0.04%, Si: 0.25%, Cr: 0.8%, Nb: 0.04%, Ti: 0.02%, Ni: 0.10%, N: 0.006%, Al / N: 6.66, balance Fe.

[0050] Manufacturing process: The pipeline steel billet obtained from the above materials is heated to approximately 1195℃ and held at that temperature for 2.8 hours. It is then rough-rolled at 1095℃ with a finishing temperature of 980℃, followed by finish rolling at 940℃ with a finishing temperature of 800℃. The total reduction rate during rough rolling is not less than 65%, and the total reduction rate during finish rolling is not less than 70%, yielding a hot-rolled plate. The hot-rolled plate is then cooled to 500℃ to obtain pipeline steel.

[0051] Performance characteristics: The pipeline steel prepared in this embodiment has a tensile strength of 620MPa~720MPa, a yield strength of 500MPa~620MPa, a low-temperature crack initiation toughness of not less than 200J at -60℃, a crack arrest toughness of not less than 300J at -40℃, a shear area of ​​not less than 85% at DWTT~30℃, and a corrosion rate of not more than 0.1mm / a in a supercritical carbon dioxide environment.

[0052] Example 4: Pipeline steel composition: C: 0.056%, Mn: 1.35%, S: 0.0005%, P: 0.0075%, Al: 0.043%, Si: 0.28%, Cr: 0.85%, Nb: 0.044%, Ti: 0.023%, Ni: 0.11%, N: 0.0067%, Al / N: 6.4, balance Fe.

[0053] Manufacturing process: The pipeline steel billet obtained from the above materials is heated to approximately 1181℃, held at that temperature for 2.9 hours, and then rough-rolled at 1085℃ with a finishing temperature of 990℃. It is then finish-rolled at 945℃ with a finishing temperature of 810℃. The total reduction rate during rough rolling is not less than 65%, and the total reduction rate during finish rolling is not less than 70%, resulting in a hot-rolled plate. The hot-rolled plate is then cooled to 500℃ to obtain pipeline steel.

[0054] Performance characteristics: The pipeline steel prepared in this embodiment has a tensile strength of 620MPa~720MPa, a yield strength of 500MPa~620MPa, a low-temperature crack initiation toughness of not less than 200J at -60℃, a crack arrest toughness of not less than 300J at -40℃, a shear area of ​​not less than 85% at DWTT~30℃, and a corrosion rate of not more than 0.1mm / a in a supercritical carbon dioxide environment.

[0055] Example 5: Pipeline steel composition: C: 0.03%, Mn: 1.35%, S: 0.0005%, P: 0.008%, Al: 0.06%, Si: 0.28%, Cr: 0.85%, Nb: 0.044%, Ti: 0.01%, Ni: 0%, N: 0.008%, Al / N: 7.5, balance Fe.

[0056] Manufacturing process: The pipeline steel billet obtained from the above materials is heated to approximately 1200℃ and held at that temperature for 3.0 hours. It is then rough-rolled at 1085℃ with a finishing temperature of 1100℃, followed by finish rolling at 950℃ with a finishing temperature of 781℃. The total reduction rate during rough rolling is 65.5%, and the total reduction rate during finish rolling is 70.5%, yielding a hot-rolled plate. The hot-rolled plate is then cooled to 453℃ to obtain pipeline steel.

[0057] Performance characteristics: The pipeline steel prepared in this embodiment has a tensile strength of 663MPa, a yield strength of 520, a low-temperature crack initiation toughness of 280J at -60℃, a crack arrest toughness of not less than 320 at -40℃, a shear area of ​​86% at DWTT~30℃, and a corrosion rate of 0.07mm / a in a supercritical carbon dioxide environment.

[0058] Example 6: Pipeline steel composition: C: 0.045%, Mn: 1.50%, S: 0.0009%, P: 0.006%, Al: 0.02%, Si: 0.22%, Cr: 0.8%, Nb: 0.04%, Ti: 0.015%, Ni: 0.05%, N: 0.006%, Al / N: 4, balance Fe. The chemical composition table is as follows: Chemical composition table of pipeline steel for supercritical carbon dioxide transmission pipelines

[0059] Manufacturing process: The pipeline steel billet obtained from the above materials is heated to approximately 1200℃, held at that temperature for 2.8 hours, and then rough-rolled at 1080℃ with a finishing temperature of 1000℃. It is then finish-rolled at 930℃ with a finishing temperature of 810℃. The total reduction rate during rough rolling is 65%, and the total reduction rate during finish rolling is 70%, yielding a hot-rolled plate. The hot-rolled plate is cooled to 500℃ to obtain pipeline steel at a cooling rate of 15℃ / s. The preparation process is as follows: Preparation process table of pipeline steel for supercritical carbon dioxide transmission pipelines

[0060] Performance characteristics: The pipeline steel prepared in this embodiment has a tensile strength of 665 MPa, a yield strength of 512 MPa, a low-temperature crack initiation toughness of 300 J at -60℃, a crack arrest toughness of 340 J at -40℃, a DWTT shear area of ​​85% at -30℃, and a corrosion rate of 0.06 mm / a in a supercritical carbon dioxide environment. The mechanical property test results are shown in the table below: Mechanical property test table for pipeline steel used in supercritical carbon dioxide transmission pipelines

[0061] The mechanical property test table of pipeline steel for supercritical carbon dioxide transmission pipelines shows that the pipeline steel for supercritical carbon dioxide transmission pipelines of the present invention has a reasonable strength and toughness match, and its supercritical carbon dioxide corrosion resistance is more than 10 times that of ordinary pipeline steel.

[0062] like Figure 1 As shown, the microstructure of the pipeline steel for supercritical carbon dioxide transmission pipelines of the present invention is ferrite + granular bainite + a small amount of pearlite.

[0063] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A pipeline steel for supercritical carbon dioxide transmission pipelines, characterized in that: The pipeline steel comprises, by mass percentage: C: 0.03%–0.07%, Mn: 1.20%–1.50%, S≤0.001%, P≤0.008%, Al≤0.06%, Si: 0.2%–0.3%, Cr: 0.5%–1.0%, Nb: 0.03%–0.05%, Ti: 0.01%–0.03%, Ni: 0–0.15%, N: 0.004%–0.008%, Al / N≥2.5, with the balance being Fe.

2. The pipeline steel for supercritical carbon dioxide transmission pipelines as described in claim 1, characterized in that: The pipeline steel has a tensile strength of 620MPa~720MPa, a yield strength of 500MPa~620MPa, a low-temperature crack initiation toughness of not less than 200J at -60℃, a crack arrest toughness of not less than 300J at -40℃, a DWTT shear area of ​​not less than 85% at -30℃, and a corrosion rate of not more than 0.1mm / a.

3. A method for manufacturing pipeline steel for supercritical carbon dioxide transmission pipelines as described in any one of claims 1-2, characterized in that, The manufacturing method includes: The pipeline steel billet is heated, kept at a constant temperature, rough rolled, and finish rolled to obtain a hot-rolled plate; The pipeline steel is obtained by cooling the hot-rolled plate.

4. The method for manufacturing pipeline steel for supercritical carbon dioxide transmission pipelines as described in claim 3, characterized in that: The heating temperature is 1180℃~1200℃.

5. The method for manufacturing pipeline steel for supercritical carbon dioxide transmission pipelines as described in claim 3, characterized in that: The heat preservation time is 2.5h to 3.0h.

6. The method for manufacturing pipeline steel for supercritical carbon dioxide transmission pipelines as described in claim 3, characterized in that: In the rough rolling process, the initial rolling temperature is 1080℃~1100℃, and the final rolling temperature is 970℃~1000℃.

7. The method for manufacturing pipeline steel for supercritical carbon dioxide transmission pipelines as described in claim 3, characterized in that: In the finishing rolling process, the initial rolling temperature is 900℃~950℃, and the final rolling temperature is 780℃~820℃.

8. The method for manufacturing pipeline steel for supercritical carbon dioxide transmission pipelines as described in claim 3, characterized in that: The cooling temperature is 450℃~580℃.

9. The method for manufacturing pipeline steel for supercritical carbon dioxide transmission pipelines as described in claim 3, characterized in that: The cooling rate is 8℃ / s to 15℃ / s.

10. The method for manufacturing pipeline steel for supercritical carbon dioxide transmission pipelines as described in claim 3, characterized in that: The cooling method is water cooling.

Images