Pipeline steel for carbon dioxide conveying and production method thereof

Abstract

The invention discloses pipeline steel for carbon dioxide conveying and a production method thereof, and relates to the technical field of steel production, and the pipeline steel comprises the following chemical components in percentage by mass: 0.03%-0.07% of C, 0.10%-0.40% of Si, 1.00%-1.40% of Mn, less than or equal to 0.013% of P, less than or equal to 0.0020% of S, 0.030%-0.070% of Nb, less than or equal to 0.010% of V, 0.008%-0.030% of Ti, 0.20%-0.40% of Cr, 0.10%-0.30% of Ni, 0.05%-0.15% of Mo, less than or equal to 0.010% of Cu, 0.015%-0.055% of Al, less than or equal to 0.00050% of B, 0.0006%-0.0030% of Ca, less than or equal to According to the invention, a structure form taking bainite as a main component is realized, and the performance requirement of a product is met.

Description

Technical Field

[0001] The present invention relates to the technical field of steel production, and in particular to a pipeline steel for transporting carbon dioxide and a production method thereof. Background Art

[0002] China's capture, utilization and storage technology development roadmap focuses on the development prospects of CO2 pipelines. The annual demand for my country's CO2 pipeline development plan is about 200,000 tons / year, the demand for corrosion-resistant alloy and bimetallic composite pipes is about 60,000 tons / year, and the demand for low-carbon micro-alloy steel pipes is about 140,000 tons / year. Domestic CO2 long-distance pipelines are in the initial stage, and the transmission pressure of the built CO2 pipelines generally does not exceed 4.8MPa.

[0003] The performance requirements of steel pipes for transporting carbon dioxide are strict. The -10℃ DWTT and -30℃ steel plate characteristic CTOD value δm should not be less than 0.3mm, which is a test of toughness stability. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the disadvantages of the prior art and provide a pipeline steel for transporting carbon dioxide and a production method thereof.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows: A pipeline steel for transporting carbon dioxide, whose chemical composition and mass percentage are as follows: C: 0.03%-0.07%, Si: 0.10%-0.40%, Mn: 1.00%-1.40%, P:≤0.013%, S:≤0.0020%, Nb: 0.030-0.070%, V: ≤0.010%, Ti: 0.008-0.030%, Cr: 0.20-0.40%, Ni: 0.10%-0.30%, Mo: 0.05%-0.15%, Cu: ≤0.010%, Al: 0.015%-0.055%, B≤0.00050%, Ca: 0.0006%-0.0030%, N≤0.0060%, H≤0.0002%, and the balance is Fe and unavoidable impurities.

[0006] As a preferred embodiment of the carbon dioxide transportation pipeline steel of the present invention, its chemical composition and mass percentage are as follows: C: 0.03%-0.05%, Si: 0.10%-0.30%, Mn: 1.00%-1.30%, P:≤0.013%, S:≤0.0020%, Nb: 0.030-0.050%, V: ≤0.010%, Ti: 0.008-0.020%, Cr: 0.20-0.30%, Ni: 0.10%-0.20%, Mo: 0.05%-0.13%, Cu:≤0.010%, Al: 0.015%-0.050%, B≤0.00050%, Ca: 0.0006%-0.0020%, N≤0.0060%, H≤0.0002%, and the balance is Fe and unavoidable impurities.

[0007] As a preferred embodiment of the carbon dioxide transportation pipeline steel of the present invention, its chemical composition and mass percentage are as follows: C: 0.04%-0.07%, Si: 0.20%-0.40%, Mn: 1.00%-1.40%, P:≤0.013%, S:≤0.0020%, Nb: 0.030-0.070%, V: ≤0.010%, Ti: 0.015-0.030%, Cr: 0.30-0.40%, Ni: 0.20%-0.30%, Mo: 0.08%-0.15%, Cu:≤0.010%, Al: 0.020%-0.055%, B≤0.00050%, Ca: 0.0010%-0.0030%, N≤0.0060%, H≤0.0002%, and the balance is Fe and unavoidable impurities.

[0008] The present invention also provides a method for producing pipeline steel for transporting carbon dioxide, comprising the following steps: S1, sending the molten steel after KR desulfurization, converter smelting, LF or RH treatment to continuous casting for casting treatment; S2, using a vertical bending continuous casting machine for casting, and using electromagnetic stirring technology for stirring, using dynamic light pressure reduction process for processing, and stacking cooling for 48 hours after casting for surface inspection; S3. The billet that has passed the surface inspection is subjected to austenitization heating, the tapping temperature is 1080-1120°C, and two-stage rolling is adopted, the reduction rate of the last pass of rough rolling is not less than 22%, and the finishing rolling adopts even pass rolling; S4. Cool the rolled steel plates, and then stack, shear, mark and store the cooled steel plates.

[0009] As a preferred solution of the production method of pipeline steel for transporting carbon dioxide according to the present invention, the stirring by electromagnetic stirring technology comprises: 220mm cross-section current setting 260A ~ 280A, frequency 5.0 ~ 6.0HZ; 260mm cross-section current setting 280A~320A, frequency 5.0~6.0HZ; 320mm cross section current setting 330~360A, frequency 5.0~6.0HZ; The current setting for 370mm section is 380A~420A, and the frequency is 5.0~6.0HZ.

[0010] As a preferred embodiment of the method for producing pipeline steel for transporting carbon dioxide according to the present invention, in step S2, the casting superheat is 30-40°C, and the continuous casting speed is 0.6-0.9 m / min.

[0011] As a preferred embodiment of the method for producing pipeline steel for transporting carbon dioxide according to the present invention, in step S3, the second rolling temperature is 770-810°C, and the final rolling temperature is 780-820°C.

[0012] As a preferred embodiment of the method for producing pipeline steel for transporting carbon dioxide according to the present invention, in step S4, the water inlet temperature for cooling the steel plate is 740-760°C, the cooling rate is 15-20°C / min, and the red-return temperature is 400-500°C.

[0013] The beneficial effects of the present invention are: (1) The present invention adopts a low-carbon design to effectively increase the ferrite content. The low-manganese design can reduce the harm of manganese sulfide and ensure the core quality of thick-walled pipelines. The chromium element can improve the hardenability of thick-walled pipelines and improve the uniformity of the structure in the thickness direction of thick-walled pipelines. The molybdenum element can improve the strength of thick-gauge products and improve the hardenability of thick-gauge products. The nickel element can improve the adverse effects of low carbon and stabilize the strength of steel. The simultaneous use of nickel and chromium can improve the strength and toughness of thick-walled pipelines to a limited extent and improve the comprehensive mechanical properties after welding. The nickel element can promote the nucleation of austenite crystals to refine the grain size of the structure, strengthen the intergranular structure, and improve the low-temperature toughness of steel.

[0014] (2) The present invention improves the superheat, which can improve the purity of molten steel and the liquid core temperature during the casting process. By dynamically reducing the pressure with a large amount of pressure, the quality of the core of the ingot can be effectively changed, thereby improving the low-temperature drop hammer performance of thick-walled products and improving the CTOD performance of the products.

[0015] (3) The present invention solves the segregation problem in the center and 1 / 4 of the thick-walled ingot by using intermittent electromagnetic stirring technology, improves the uniformity of the structure in the thickness direction, improves the low-temperature toughness and CTOD performance, and enhances the stability of the product's CO2 transport performance.

[0016] (4) The austenite temperature in the present invention effectively improves the problem of coarse structure in the core and 1 / 4 of the ingot, reduces the adverse effects of the banded structure, refines the grain size and density of the structure, thereby improving the stability of the transverse and longitudinal mechanical properties of the product and improving the stability of the low-temperature drop hammer and CTOD.

[0017] (4) The control of the rolling process and cooling rate in the present invention improves and promotes the stability of the structural transformation, obtains a stable ferrite structure, and can improve the strength and toughness of the product, and enhance the stability of the mechanical properties and low-temperature toughness of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0019] Figure 1 This is a schematic metallographic diagram of the pipeline steel for transporting carbon dioxide provided by the present invention. DETAILED DESCRIPTION

[0020] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific implementation modes and in combination with the accompanying drawings.

[0021] Example 1: This example provides a pipeline steel for transporting carbon dioxide and a production method thereof, wherein the chemical composition and mass percentage are as follows: C: 0.04%, Si: 0.19%, Mn: 1.23%, P: 0.010%, S: 0.0013%, Nb: 0.042%, V: 0.003%, Ti: 0.017%, Cr: 0.26%, Ni: 0.17%, Mo: 0.09%, Cu: 0.02%, Al: 0.033%, B: 0.00020%, Ca: 0.0017%, N: 0.00:33%, H: 0.00011%, and the balance is Fe and unavoidable impurities.

[0022] This embodiment also provides a method for producing pipeline steel for transporting carbon dioxide, comprising the following steps: S1, sending the molten steel after KR desulfurization, converter smelting, LF or RH treatment to continuous casting for casting treatment; S2. Vertical bending continuous casting machine is used for casting, the casting superheat is 36℃, the continuous casting speed is 0.85m / min, and electromagnetic stirring technology is used for stirring. The stirring roller is placed on the 2# roller, and the power is supplied at a frequency of 6 seconds. The current of 220mm section is set to 270A, the frequency is 5.5HZ, and the dynamic light pressure reduction process is used for processing. The maximum pressure reduction is 11mm. After the casting, the billet is piled and cooled for 48 hours for surface inspection; S3. The billet that has passed the surface inspection is austenitized and heated, the tapping temperature is 1098℃, and two-stage rolling is adopted, the final rough rolling reduction rate is not less than 22%, the finishing rolling adopts even-pass rolling, the second rolling temperature is 805℃, and the final rolling temperature is 796℃; S4. The rolled steel plates are cooled with a water inlet temperature of 753°C, a cooling rate of 17°C / min, and a red-return temperature of 485°C. The cooled steel plates are then pile-cooled, sheared, marked, and stored.

[0023] Example 2: This example provides a pipeline steel for transporting carbon dioxide and a production method thereof, wherein the chemical composition and mass percentage are as follows: C: 0.06%, Si: 0.33%, Mn: 1.06%, P: 0.010%, S: 0.0015%, Nb: 0.063%, V: 0.002%, Ti: 0.023%, Cr: 0.37%, Ni: 0.29%, Mo: 0.13%, Cu: 0.03%, Al: 0.041%, B: 0.00030%, Ca: 0.0022%, N: 0.0041%, H≤0.00010%, and the balance is Fe and unavoidable impurities.

[0024] This embodiment also provides a method for producing pipeline steel for transporting carbon dioxide, comprising the following steps: S1, sending the molten steel after KR desulfurization, converter smelting, LF or RH treatment to continuous casting for casting treatment; S2. Vertical bending continuous casting machine is used for casting, the casting superheat is 36℃, the continuous casting speed is 0.85m / min, and electromagnetic stirring technology is used for stirring. The stirring roller is placed at the 2# roller, and the power is supplied at a frequency of 6 seconds. The current of 370mm section is set to 390A, the frequency is 5.5HZ, and the dynamic light pressure reduction process is used for processing. The maximum pressure reduction is 12mm. After the casting, the billet is piled and cooled for 48 hours for surface inspection; S3. The billet that has passed the table inspection is subjected to austenitization heating, the tapping temperature is 1102°C, and two-stage rolling is adopted, the reduction rate of the final rough rolling is not less than 22%, the finishing rolling adopts even-pass rolling, the second rolling temperature is 770°C, and the final rolling temperature is 783°C; S4. Cool the rolled steel plate with a water inlet temperature of 745°C, a cooling rate of 15°C / min, and a red-return temperature of 420°C. The cooled steel plate is then pile-cooled, sheared, marked, and stored.

[0025] The mechanical properties of Examples 1 and 2 are as follows: The transverse and longitudinal tensile properties are shown in Table 1.

[0026]

[0027] Table 1 See Table 2 for -40℃ low-temperature impact toughness, -10℃ DWTT performance, and -30℃ steel plate characteristic CTOD value δm.

[0028]

[0029] Table 2 It can be seen from this that the technical solution of the present application realizes a bainite-based organizational structure, meets the product's transverse and longitudinal tensile performance requirements, the product's -10°C DWTT, and -30°C steel plate characteristic CTOD value δm not less than 0.3mm performance requirements.

[0030] In addition to the above embodiments, the present invention may also have other implementation modes; any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A pipeline steel for transporting carbon dioxide, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.03%~0.07%, Si: 0.10%~0.40%, Mn: 1.00%~1.40%, P:≤0.013%, S:≤0.0020%, Nb: 0.030~0.070%, V: ≤0.010%, Ti: 0.008~0.030%, Cr: 0.20~0.40%, Ni: 0.10%~0.30%, Mo: 0.05%~0.15%, Cu: ≤0.010%, Al: 0.015%~0.055%, B≤0.00050%, Ca: 0.0006%~0.0030%, N≤0.0060%, H≤0.0002%, and the balance is Fe and unavoidable impurities.

2. The carbon dioxide transport pipeline steel according to claim 1, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.03%~0.05%, Si: 0.10%~0.30%, Mn: 1.00%~1.30%, P:≤0.013%, S:≤0.0020%, Nb: 0.030~0.050%, V: ≤0.010%, Ti: 0.008~0.020%, Cr: 0.20~0.30%, Ni: 0.10%~0.20%, Mo: 0.05%~0.13%, Cu: ≤0.010%, Al: 0.015%~0.050%, B≤0.00050%, Ca: 0.0006%~0.0020%, N≤0.0060%, H≤0.0002%, and the balance is Fe and unavoidable impurities.

3. The carbon dioxide transport pipeline steel according to claim 1, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.04%~0.07%, Si: 0.20%~0.40%, Mn: 1.00%~1.40%, P:≤0.013%, S:≤0.0020%, Nb: 0.030~0.070%, V: ≤0.010%, Ti: 0.015~0.030%, Cr: 0.30~0.40%, Ni: 0.20%~0.30%, Mo: 0.08%~0.15%, Cu: ≤0.010%, Al: 0.020%~0.055%, B≤0.00050%, Ca: 0.0010%~0.0030%, N≤0.0060%, H≤0.0002%, and the balance is Fe and unavoidable impurities.

4. A method for producing a pipeline steel for transporting carbon dioxide according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, sending the molten steel after KR desulfurization, converter smelting, LF or RH treatment to continuous casting for casting treatment; S2, using a vertical bending continuous casting machine for casting, and using electromagnetic stirring technology for stirring, using dynamic light pressure reduction process for processing, and stacking cooling for 48 hours after casting for surface inspection; S3. The billet that has passed the surface inspection is subjected to austenitization heating, the tapping temperature is 1080-1120°C, and two-stage rolling is adopted, the reduction rate of the last pass of rough rolling is not less than 22%, and the finishing rolling adopts even pass rolling; S4. Cool the rolled steel plates, and then stack, shear, mark and store the cooled steel plates.

5. The method for producing pipeline steel for transporting carbon dioxide according to claim 4, characterized in that: The stirring by electromagnetic stirring technology comprises: 220mm cross-section current setting 260A ~ 280A, frequency 5.0 ~ 6.0HZ; 260mm cross-section current setting 280A~320A, frequency 5.0~6.0HZ; 320mm cross section current setting 330~360A, frequency 5.0~6.0HZ; The current setting for 370mm section is 380A~420A, and the frequency is 5.0~6.0HZ.

6. The method for producing pipeline steel for transporting carbon dioxide according to claim 4, characterized in that: In step S2, the casting superheat is 30-40°C, and the continuous casting speed is 0.6-0.9 m / min.

7. The method for producing pipeline steel for transporting carbon dioxide according to claim 4, characterized in that: In step S3, the second rolling temperature is 770-810°C, and the final rolling temperature is 780-820°C.

8. The method for producing pipeline steel for transporting carbon dioxide according to claim 4, characterized in that: In step S4, the water inlet temperature for cooling the steel plate is 740-760°C, the cooling rate is 15-20°C / min, and the red-return temperature is 400-500°C.

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