A production method for supercritical carbon dioxide corrosion-resistant steel plate L360MC

Abstract

A method for producing L360MC supercritical carbon dioxide corrosion-resistant steel plate. The chemical composition of the steel is as follows: C = 0.01% to 0.02%, Si = 0.10% to 0.30%, Mn = 0.70% to 0.90%, P ≤ 0.008%, S ≤ 0.0015%, Alt = 0.020% to 0.050%, Nb = 0.025% to 0.045%, Cr = 0.90% to 1.10%, Ti = 0.010% to 0.020%, Mo = 0.10% to 0.15%, with the remainder being Fe and unavoidable impurities. The steel plate has a multiphase structure of ferrite + pearlite and a small amount of MA. The present invention adopts a low-carbon, low-manganese, medium-chromium composition design, continuously casts into billets, and produces steel plates through the TMCP process. The steel plate has properties that combine strength, high toughness at low temperatures, low-temperature crack arrest, and high-pressure carbon dioxide corrosion resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of pipeline steel production and relates to a TMCP process supercritical carbon dioxide corrosion-resistant steel plate L360MC and a production method. Background Art

[0002] Carbon capture, utilization and storage, referred to as CCUS, is to capture and purify the carbon dioxide emitted during the production process, and then put it into the new production process for reuse and storage. CO2 transportation is an important link to achieve source-sink matching in the CCUS system, and is a key technical link to achieve large-scale engineering application of CCUS. CO2 has gaseous, supercritical, liquid or solid states, and its phase state is more complex than that of natural gas transportation. CO2 When the pressure is above the critical pressure of 7.38 MPa and the temperature is above the critical temperature of 31.1°C, it is in the supercritical state. Supercritical CO2 has a density close to that of a liquid and a viscosity close to that of a gas, with high density and low viscosity. When the entire pipeline transportation process is in the supercritical state, transportation is most efficient.

[0003] At present, the research on CO2 pipeline steel is still limited to the study of gaseous CO2 corrosion, and corrosion under supercritical CO2 conditions has not been considered; or only the single factor of corrosion has been considered, without considering the strength, low-temperature high toughness, low-temperature crack arrest and high-pressure carbon dioxide corrosion resistance as a whole, which is insufficient.

[0004] The L485M pipeline steel disclosed in Chinese patent CN201310217916.8 "Preparation method of CO2 corrosion-resistant pipeline steel for ground gathering and transportation" has carbon dioxide corrosion resistance. However, the corrosion performance under normal pressure gaseous CO2 corrosion conditions was tested, and its elongation and low-temperature performance are deficient.

[0005] The pipeline steel disclosed in Chinese patent CN202110093258.0 "A CO2 corrosion-resistant steel pipe and preparation method" has resistance to carbon dioxide corrosion, but the corrosion performance tested is still only under 0.1~0.5MPa gaseous CO2 corrosion conditions. Its elongation and low-temperature performance are still lacking, and the steel plate requires tempering heat treatment, which increases the process and cost. Summary of the Invention

[0006] The present invention aims to provide a production method for supercritical carbon dioxide corrosion-resistant steel plate L360MC to solve the key technologies of steel plates for supercritical carbon dioxide transportation. In addition to having the mechanical properties of conventional pipeline steel, the steel plate also has good low-temperature resistance, low-temperature crack arrest performance and high-pressure carbon dioxide corrosion resistance: -60°C impact ≥250J; -30°C drop hammer shear area ≥85%; average corrosion rate ≤1.0mm / a in a 15.6Mpa high-pressure supercritical carbon dioxide environment.

[0007] The technical solution of the present invention:

[0008] A method for producing L360MC steel for supercritical carbon dioxide transmission pipelines. The steel's chemical composition by weight percentage is as follows: C = 0.01% to 0.02%, Si = 0.10% to 0.30%, Mn = 0.70% to 0.90%, P ≤ 0.008%, S ≤ 0.0015%, Alt = 0.020% to 0.050%, Nb = 0.025% to 0.045%, Cr = 0.90% to 1.10%, Ti = 0.010% to 0.020%, Mo = 0.10% to 0.15%, with the remainder being Fe and unavoidable impurities. Key process steps include:

[0009] (1) Steelmaking: The converter tapping temperature is controlled at P≤0.006%; the LF+VD combination is used for refining, and the temperature is rapidly raised to form slag after stirring and decarburization in LF, and the outlet S≤0.0015%; the VD vacuum maintenance time is ≥12 minutes, and the soft blowing is ≥15 minutes; the molten steel meeting the composition and inclusion requirements is produced;

[0010] (2) Continuous casting: Section thickness ≥ 260 mm, using dynamic soft reduction technology and low superheated steel casting to produce continuous casting billets that meet the requirements of center segregation C ≤ 1.0 level and center porosity ≤ 1.0 level;

[0011] (3) Heating: heating temperature 1150~1250℃, soaking time 20~30min;

[0012] (3) Rolling: After leaving the furnace, two-stage rolling is carried out. The end temperature of the first stage rolling is 900~1100℃, and the end temperature of the second stage rolling is 820~900℃. The cumulative reduction of finishing rolling is ≥60%;

[0013] (4) Cooling: ACC cooling is used, the cooling rate is 8~20℃ / s, and the red-return temperature after cooling is 500~580℃.

[0014] This invention offers the following advantages: Its composition design utilizes low-carbon, medium-manganese, and ultra-low phosphorus and sulfur to ensure controlled central segregation, thereby ensuring a controllable banded structure after rolling using the TMCP process, resulting in excellent low-temperature toughness, crack arrest, and weldability. Low-carbon, medium-chromium is used, with a small amount of the more expensive alloy Mo added. While Cr and Mo contribute to their corrosion resistance, the low-carbon balance ensures excellent low-temperature resistance and crack arrest. Furthermore, microalloying with alloying elements such as Nb and Ti maximizes grain refinement, precipitation strengthening, and phase transformation strengthening, achieving strength, low-temperature toughness, crack arrest, and corrosion resistance that meet the requirements for use in supercritical CO2 corrosive environments. The TMCP process offers low production costs and short lead times, providing competitive advantages in both cost and delivery. The L360MC steel plate produced using this invention exhibits a multiphase structure of ferrite + pearlite with a small amount of MA, a banded structure of grade 0.5 or below, and inclusions less than grade 1.0. This results in a well-matched strength and toughness profile, resulting in uniform and stable performance. In addition to meeting the mechanical properties of conventional pipelines, the impact resistance at -60℃ is ≥250J; the drop hammer shear area at -30℃ is ≥85%; and the average corrosion rate in a 15.6Mpa high-pressure supercritical CO2 environment is ≤1.0mm / a. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the metallographic structure diagram of the steel plate in Example 1. DETAILED DESCRIPTION

[0016] The present invention is further described below with reference to the embodiments. Example 1

[0017] A TMCP process supercritical carbon dioxide corrosion-resistant steel plate L360MC and its production method. The chemical composition of the steel by weight percentage is: C = 0.02%, Si = 0.16%, Mn = 0.85%, P = 0.006%, S = 0.001%, Alt = 0.030%, Nb = 0.040%, Cr = 1.00%, Ti = 0.012%, Mo = 0.12%, and the balance is Fe and unavoidable impurities. The process steps are as follows:

[0018] (1) Steelmaking: The converter tapping temperature is controlled at P≤0.006%; the LF+VD combination is used for refining, and after stirring and decarburizing in LF, the temperature is quickly raised to form slag, and the outlet S=0.0012%; the VD vacuum maintenance time is ≥12 minutes, and the soft blowing is ≥15 minutes; the molten steel with satisfactory composition and inclusions is produced;

[0019] (2) Continuous casting: Section thickness * width: 260mm * 2070, using dynamic soft reduction technology and low superheat steel casting, low center segregation C ≤ 1.0 level, center porosity ≤ 1.0 level;

[0020] (3) Heating: heating temperature 1220℃, soaking time 25min;

[0021] (3) Rolling: After leaving the furnace, two-stage rolling is carried out, the end temperature of the first stage rolling is 1050℃, the end temperature of the second stage rolling is 860℃, and the cumulative reduction of finishing rolling is 65%;

[0022] (4) Cooling: ACC cooling is used, the cooling rate is 15℃ / s, and the red-return temperature after cooling is 540℃. Example 2

[0023] A TMCP process supercritical carbon dioxide corrosion-resistant steel plate L360MC and its production method. The chemical composition of the steel is: C = 0.015%, Si = 0.13%, Mn = 0.80%, P = 0.006%, S = 0.0012%, Alt = 0.030%, Nb = 0.040%, Cr = 1.05%, Ti = 0.015%, Mo = 0.14%, with the balance being Fe and unavoidable impurities. The key process steps include:

[0024] (1) Steelmaking: The converter tapping control P=0.004%; the LF+VD combination is used for refining, and after stirring and decarburizing in LF, the temperature is quickly raised to form slag, and the outlet S=0.0013%; the VD vacuum maintenance time is ≥12min, and the soft blowing is ≥15min; the molten steel that meets the composition and inclusion requirements is produced;

[0025] (2) Continuous casting: section thickness ≥ 260 mm, using dynamic soft reduction technology and low superheat steel casting, low center segregation C ≤ 1.0 level, center porosity ≤ 1.0 level;

[0026] (3) Heating: heating temperature 1205℃, soaking time 25min;

[0027] (3) Rolling: After leaving the furnace, two-stage rolling is carried out, the end temperature of the first stage rolling is 1025℃, the end temperature of the second stage rolling is 850℃, and the cumulative reduction of finishing rolling is 68%;

[0028] (4) Cooling: ACC cooling is used, the cooling rate is 15℃ / s, and the red-return temperature after cooling is 510℃.

[0029] Table 1 Comparison of performance test results of Example L360MC and ordinary L360M

[0030] .

[0031] It can be seen from the embodiments that the steel plate produced by the method of the present invention has a yield strength of 430~440MPa, a tensile strength of 490~520MPa, an impact strength of 396~436J at low temperature of -60℃, a shear area of ​​98%~99% at a drop hammer at -30℃, and an average corrosion rate of 0.58~0.63mm / a in a 15.6Mpa high-pressure supercritical carbon dioxide environment. The steel plate has performance that combines strength, high toughness at low temperature, low-temperature crack arrest and high-pressure carbon dioxide corrosion resistance.

Claims

1. A method for producing a supercritical carbon dioxide corrosion-resistant steel plate L360MC, characterized by: The chemical composition of the steel is as follows: C = 0.01% ~ 0.02%, Si = 0.10% ~ 0.30%, Mn = 0.70% ~ 0.90%, P ≤ 0.008%, S ≤ 0.0015%, Alt = 0.020% ~ 0.050%, Nb = 0.025% ~ 0.045%, Cr = 0.90% ~ 1.10%, Ti = 0.010% ~ 0.020%, Mo = 0.10% ~ 0.15%, the remainder being Fe and unavoidable impurities; the steel plate is a multiphase structure of ferrite + pearlite and a small amount of MA, with an impact load of ≥ 250J at -60°C and a drop shear area of ​​≥ 85% at -30°C. The average corrosion rate of steel plates in a 15.6 MPa high-pressure supercritical CO2 environment is ≤1.0 mm / a; The key process steps include: (1) Steelmaking: The converter tapping temperature is controlled at P≤0.006%; the LF+VD combination is used for refining, and after stirring and decarburizing in LF, the temperature is quickly raised to form slag, and the outlet S is ≤0.0015%; the VD vacuum maintenance time is ≥12 minutes, and the soft blowing is ≥15 minutes; (2) Continuous casting: Section thickness ≥ 260 mm, using dynamic soft reduction technology and low superheated steel casting to produce continuous casting billets that meet the requirements of center segregation C ≤ 1.0 level and center porosity ≤ 1.0 level; (3) Heating: heating temperature 1150~1250℃, soaking time 20~30min; (3) Rolling: After leaving the furnace, two-stage rolling is carried out. The end temperature of the first stage rolling is 900~1100℃, and the end temperature of the second stage rolling is 820~900℃. The cumulative reduction of finishing rolling is ≥60%; (4) Cooling: ACC cooling is used, the cooling rate is 8~20℃ / s, and the red-return temperature after cooling is 500~580℃.

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