A steel for resisting carbon dioxide corrosion and a method for producing the same

Abstract

The application relates to the technical field of steel production, in particular to a carbon dioxide corrosion-resistant steel and a preparation method thereof.The chemical components of the steel include C, Cr, Mn, Nb, Si, P, S and Fe; wherein the content of C is 0.05-0.15 wt%, the content of Cr is 1-3 wt%, the content of Mn is 1-1.5 wt%, the content of Nb is 0.025-0.055 wt%, the content of Si is 0.2-0.3 wt%, the content of P is <=0.008 wt%, and the content of S is <=0.002 wt%. The application solves the technical problem that the existing steel has poor carbon dioxide corrosion resistance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of steel production, and in particular to a carbon dioxide corrosion-resistant steel and a preparation method thereof. BACKGROUND

[0002] Carbon dioxide flooding technology is a mature oil production technology with high recovery ratio in low-permeability reservoir exploitation. According to statistics, the proven low-permeability oil reserves in China amount to 15 billion tons, and the carbon dioxide flooding technology can produce 48 billion tons of oil at the conservative estimate and up to 100 billion tons at the maximum, which can increase the production by more than 5 billion tons. With the wide application of the carbon dioxide flooding technology and the increase of oil production and demand, the content of carbon dioxide in the produced oil and gas increases, and the partial pressure of carbon dioxide in the conveying medium continuously increases due to the design requirement of long-distance and large-flow conveying.

[0003] Dry carbon dioxide has no corrosion to steel, but carbon dioxide dissolved in water has strong corrosiveness. At the same pH value, the total acidity of CO2 is higher than that of hydrochloric acid, so the corrosion of CO2 to steel is more serious than that of hydrochloric acid. Therefore, in order to improve the safety during service, the corrosion resistance to carbon dioxide is increasingly stringent. SUMMARY

[0004] The application provides a carbon dioxide corrosion-resistant steel and a preparation method thereof, so as to solve the technical problem of poor carbon dioxide corrosion resistance of the existing steel.

[0005] In a first aspect, the application provides a carbon dioxide corrosion-resistant steel, and the chemical composition of the steel comprises:

[0006] C, Cr, Mn, Nb, Si, P, S and Fe; wherein,

[0007] The content of C is 0.05wt%-0.15wt%, the content of Cr is 1wt%-3wt%, the content of Mn is 1wt%-1.5wt%, the content of Nb is 0.025wt%-0.055wt%, the content of Si is 0.2wt%-0.3wt%, the content of P is ≤0.008wt%, and the content of S is ≤0.002wt%.

[0008] Optionally, in the chemical composition of the steel, the content of C is 0.07wt%-0.08wt%, the content of Cr is 1.5wt%-2.1wt%, the content of Mn is 1wt%-1.1wt%, the content of Nb is 0.035wt%-0.04wt%, and the content of Si is 0.2wt%-0.21wt%.

[0009] Optionally, in the environment with a CO2 partial pressure of ≥2MPa, the corrosion rate of the steel is ≤0.05mm / a.

[0010] Optionally, the yield strength of the steel is ≥550 MPa, the tensile strength of the steel is ≥600 MPa, and the impact energy of the steel at -20℃ is ≥120 J.

[0011] In a second aspect, the application provides a method for preparing a steel for resisting carbon dioxide corrosion, for preparing the steel of any one of the embodiments of the first aspect, the method comprising:

[0012] heating the cast blank under a first set temperature;

[0013] rolling the heated cast blank to obtain a hot-rolled plate; wherein the rolling comprises:

[0014] rough rolling the heated cast blank under a first set rough rolling temperature and a first set finish rolling temperature;

[0015] finish rolling the rough-rolled cast blank under a second set rough rolling temperature and a second set finish rolling temperature;

[0016] heat treating the hot-rolled plate to obtain the steel for resisting carbon dioxide corrosion; wherein the heat treating comprises:

[0017] quenching the hot-rolled plate under a second set temperature;

[0018] tempering the quenched hot-rolled plate under a third set temperature.

[0019] Optionally, the second set temperature is 880-920℃.

[0020] Optionally, the third set temperature is 580-620℃.

[0021] Optionally, the first set temperature is 1200-1250℃.

[0022] Optionally, the first set rough rolling temperature is 1200-1250℃, and / or the first set finish rolling temperature is 980-1040℃.

[0023] Optionally, the second set rough rolling temperature is 830-850℃, and / or the second set finish rolling temperature is 770-810℃.

[0024] The above technical solutions provided by the embodiments of the application have the following advantages compared with the prior art:

[0025] The anti-carbon dioxide corrosion steel provided by the embodiment of the present application has the following advantages: the content of C is controlled to enhance the strength of the steel plate and reduce the alloy design cost; the content of Cr is controlled to improve the corrosion resistance and oxidation resistance of the steel; the content of Mn is controlled to improve the strength and hardenability of the steel plate; the content of Nb is controlled to refine the grain size of the steel plate, thereby improving the strength and toughness and improving the anti-carbon dioxide corrosion capacity; and the content of Si is controlled to improve the strength, tempering stability and anti-carbon dioxide corrosion resistance of the steel plate. In summary, the present application solves the technical problem of poor anti-carbon dioxide corrosion capacity of the existing steel material, and under the conditions of a temperature of 20-120 DEG C, a CO2 partial pressure of 2 MPa, a liquid phase flow rate of 1.0-2.5 m / s and a Cl - concentration of 10,000 mg / L, the corrosion rate of the steel plate is below 0.05 mm / a, and the mechanical properties of the steel material are ensured. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and serve to explain the principles of the present application together with the specification.

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0028] Figure 1 The flowchart of the preparation method of the anti-carbon dioxide corrosion steel provided by the embodiment of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative effort fall within the protection scope of the present application.

[0030] Various embodiments of the present application can exist in a range of forms; it should be understood that the description in a range form is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the range described has been specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has been specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single values within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in this document, it refers to any cited number (fraction or integer) within the indicated range.

[0031] In the present application, the orientation words such as "upper" and "lower" are specifically the directions of the drawing surface in the drawings, unless otherwise stated. In addition, in the description of the present application, the terms "include", "contain" and the like mean "include but are not limited to". In this document, relational terms such as "first" and "second" and the like are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this document, "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the cases of A alone, A and B together, and B alone. Wherein A, B can be singular or plural. In this document, "one or more" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, c can be single or multiple.

[0032] Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased on the market or can be prepared by existing methods.

[0033] In a first aspect, the present application provides a steel for resisting carbon dioxide corrosion, the chemical composition of the steel comprising:

[0034] C, Cr, Mn, Nb, Si, P, S and Fe; wherein,

[0035] The content of C is 0.05%-0.15% by weight, the content of Cr is 1%-3% by weight, the content of Mn is 1%-1.5% by weight, the content of Nb is 0.025%-0.055% by weight, the content of Si is 0.2%-0.3% by weight, the content of P is ≤0.008% by weight, and the content of S is ≤0.002% by weight.

[0036] The anti-carbon dioxide corrosion steel provided by the embodiments of the present application can enhance the strength of the steel plate and reduce the alloy design cost by controlling the content of C; can improve the corrosion resistance and oxidation resistance of the steel by controlling the content of Cr; can improve the strength and hardenability of the steel plate by controlling the content of Mn; can refine the grain size of the steel plate, thereby improving the strength and toughness and the anti-carbon dioxide corrosion capacity by controlling the content of Nb; and can improve the strength, temper stability and anti-carbon dioxide corrosion resistance of the steel plate by controlling the content of Si. In summary, the present application solves the technical problem of poor anti-carbon dioxide corrosion capacity of existing steel materials, and under the conditions of a temperature of 20-120 ℃, a CO2 partial pressure of ≥2 MPa, a liquid phase flow rate of 1.0-2.5 m / s and a Cl - concentration of 10,000 mg / L, the corrosion rate of the steel plate is below 0.05 mm / a, and the mechanical properties of the steel material are ensured.

[0037] The positive effect of controlling the content of C to be 0.05%-0.15% by weight is that carbon can improve the strength of the steel plate and reduce the addition amount of other alloy elements, thereby reducing the alloy design cost. If the content of C is too high, the welding performance, plasticity and impact performance will be adversely affected to some extent; if the content of C is too low, the strength requirement cannot be met to some extent. Specifically, the content of C can be 0.05% by weight, 0.08% by weight, 0.11% by weight, 0.15% by weight, etc.

[0038] The positive effect of controlling the content of Cr to be 1%-3% by weight is that chromium can improve the corrosion resistance and oxidation resistance of the steel and is one of the most commonly used elements for improving corrosion resistance. Cr can improve corrosion resistance mainly by improving the structure, compactness and stability of the corrosion product film. Cr is enriched in the carbon dioxide corrosion film, making the corrosion product film have anion selectivity and being able to quickly repair after being damaged, thereby reducing the local corrosion sensitivity and improving the corrosion resistance. If the content of Cr is too high, the cost will be too high to some extent; if the content of Cr is too low, the strength of the steel plate will be too low to some extent. Specifically, the content of Cr can be 1% by weight, 2% by weight, 3% by weight, etc.

[0039] The positive effect of controlling the content of Mn to be 1-1.5 wt%: manganese can significantly improve the strength of the steel and the hardenability of the steel plate. If the content of Mn is too high, it will form manganese segregation to some extent, resulting in uneven distribution of elements in the billet and uneven organization type of the steel plate; if the content of Mn is too low, it will result in low strength of the steel plate to some extent. Specifically, the content of Mn can be 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, etc.

[0040] The positive effect of controlling the content of Nb to be 0.025-0.055 wt%: niobium can effectively refine the grain size, thereby improving the strength and toughness; the precipitation strengthening effect of niobium precipitates can also effectively improve the strength of the steel plate. In addition, niobium also has the effects of resisting carbon dioxide corrosion and improving welding performance. If the content of Nb is too high, it will cause the production cost to rise to some extent; if the content of Nb is too low, the effect of refining the grain size will not be obvious to some extent. Specifically, the content of Nb can be 0.025, 0.030 wt%, 0.035 wt%, 0.040 wt%, 0.045 wt%, 0.050 wt%, 0.055 wt%, etc.

[0041] The positive effect of controlling the content of Si to be 0.2-0.3 wt%: silicon can effectively improve the strength and tempering stability of the steel plate, and also has the effect of resisting carbon dioxide corrosion. If the content of Si is too high, it will reduce the toughness and plasticity of the steel plate to some extent; if the content of Si is too low, it will result in low strength of the steel plate to some extent. Specifically, the content of Si can be 0.2 wt%, 0.25 wt%, 0.3 wt%, etc.

[0042] The positive effect of controlling the content of P to be ≤0.008 wt%: to ensure the purity of the steel plate and reduce the segregation of impurity elements. If the content of P is too high, it will easily cause segregation to some extent, which will adversely affect the comprehensive performance of the steel plate. Specifically, the content of P can be 0.008 wt%, 0.007 wt%, etc.

[0043] The positive effect of controlling the content of S to be ≤0.002 wt%: to ensure the purity of the steel plate, reduce the combination of S and Mn elements, and prevent the formation of MnS inclusions. If the content of S is too high, it will have a very adverse effect on the strength, toughness, etc. of the steel plate to some extent. Specifically, the content of S can be 0.002 wt%, 0.0015 wt%, etc.

[0044] In some embodiments, the content of C in the chemical composition of the steel is 0.07wt%-0.08wt%, the content of Cr is 1.5wt%-2.1wt%, the content of Mn is 1wt%-1.1wt%, the content of Nb is 0.035wt%-0.04wt%, and the content of Si is 0.2wt%-0.21wt%.

[0045] In the embodiments of the present application, the above components are preferred embodiments.

[0046] In some embodiments, the corrosion rate of the steel is ≤0.05mm / a in an environment with a CO2 partial pressure ≥2MPa.

[0047] In the embodiments of the present application, under the conditions of a temperature of 20-120℃, a CO2 partial pressure ≥2MPa, a liquid phase flow rate of 1.0-2.5m / s, and a Cl - concentration of 10000mg / L, the carbon dioxide corrosion rate is below 0.05mm / a, and the steel plate still has strong carbon dioxide corrosion resistance under the service condition of a high carbon dioxide partial pressure, thereby improving the service cycle and safety of the steel plate.

[0048] In some embodiments, the yield strength of the steel is ≥550MPa, the tensile strength of the steel is ≥600MPa, and the impact energy of the steel at-20℃ is ≥120J.

[0049] The above steel plate not only has excellent carbon dioxide corrosion resistance, but also has the above excellent mechanical properties.

[0050] In a second aspect, the present application provides a preparation method of a steel resistant to carbon dioxide corrosion, please refer to Figure 1 for preparing the steel of any one of the embodiments of the first aspect, the method comprising:

[0051] S1, heating a casting blank under a first set temperature;

[0052] S2, rolling the heated casting blank to obtain a hot-rolled plate; wherein the rolling comprises:

[0053] coarsely rolling the heated casting blank under a first set rough rolling temperature and a first set finish rolling temperature;

[0054] finely rolling the coarsely rolled casting blank under a second set rough rolling temperature and a second set finish rolling temperature;

[0055] S3, heat treating the hot-rolled plate to obtain a steel resistant to carbon dioxide corrosion; wherein the heat treatment comprises:

[0056] quenching the hot-rolled plate at a second set temperature;

[0057] tempering the quenched hot-rolled plate at a third set temperature.

[0058] The "first set temperature" refers to a heating temperature. The "first set roughing-in temperature" refers to a roughing-in temperature of rough rolling, the "first set roughing-out temperature" refers to a roughing-out temperature of rough rolling, the "second set roughing-in temperature" refers to a roughing-in temperature of finish rolling, and the "second set roughing-out temperature" refers to a roughing-out temperature of finish rolling. The intermediate temperature is controlled to be 1.5-2.5 times of the finished product thickness. The "second set temperature" refers to a quenching temperature, and the "third set temperature" refers to a tempering temperature.

[0059] In some embodiments, the second set temperature is 880-920°C.

[0060] The positive effect of controlling the quenching temperature to be 880-920°C is to ensure the strength of the steel plate. If the temperature is too high, the strength of the steel plate will be reduced to some extent. If the temperature is too low, the target microstructure type cannot be obtained to some extent. Specifically, the quenching temperature can be 880°C, 890°C, 900°C, 910°C, 920°C, etc.

[0061] In some embodiments, the third set temperature is 580-620°C.

[0062] The positive effect of controlling the tempering temperature to be 580-620°C is to obtain the target microstructure type. If the temperature is too high, the microstructure type cannot be obtained to some extent. If the temperature is too low, the strength will be too high to some extent. Specifically, the tempering temperature can be 580°C, 590°C, 600°C, 610°C, 620°C, etc.

[0063] In some embodiments, the first set temperature is 1200-1250°C.

[0064] The positive effect of controlling the heating temperature to be 1200-1250°C is to reasonably control the austenite grain size. If the heating temperature is too high, the grains will be coarse to some extent. If the heating temperature is too low, the heating will be insufficient to some extent. Specifically, the heating temperature can be 1200°C, 1210°C, 1230°C, 1240°C, 1250°C, etc.

[0065] In some embodiments, the first set roughing-in temperature is 1160-1200°C, and or the first set roughing-out temperature is 980-1040°C.

[0066] The positive effect of controlling the rough rolling start rolling temperature to be 1160-1200℃ is that the austenite is fully refined, and the grains are not coarsened; if the temperature is too high, the grains will be coarsened to some extent; if the temperature is too low, the uniformity of the structure will be affected to some extent. Specifically, the rough rolling start rolling temperature can be 1160℃, 1170℃, 1180℃, 1190℃, 1200℃, etc.

[0067] The positive effect of controlling the rough rolling finish rolling temperature to be 980-1040℃ is that the grains are fully refined in the recrystallization zone; if the temperature is too high, the grains will be coarsened to some extent, and the pre-rolling temperature will be longer, affecting the production efficiency; if the temperature is too low, it will be difficult to ensure the finish rolling temperature of the finish rolling. Specifically, the rough rolling finish rolling temperature can be 980℃, 1000℃, 1020℃, 1040℃, etc.

[0068] In some embodiments, the second set start rolling temperature is 830-850℃, and or the second set finish rolling temperature is 770-810℃.

[0069] The positive effect of controlling the finish rolling start rolling temperature to be 830-850℃ is that the steel plate is ensured to be rolled in the unrecrystallization zone; if the temperature is too high, the grain size will be uneven to some extent; if the temperature is too low, it will be difficult to ensure the finish rolling temperature of the finish rolling. Specifically, the finish rolling start rolling temperature can be 830℃, 840℃, 850℃, etc.

[0070] The positive effect of controlling the finish rolling finish rolling temperature to be 770-810℃ is that the austenite grain size can be effectively controlled; if the temperature is too high, the grains will be coarsened to some extent; if the temperature is too low, it will be difficult to obtain the target structure type. Specifically, the finish rolling finish rolling temperature can be 770℃, 780℃, 790℃, 800℃, 810℃, etc.

[0071] The preparation method of the anti-carbon dioxide corrosion steel is based on the above-mentioned anti-carbon dioxide corrosion steel, and the specific steps of the preparation method of the anti-carbon dioxide corrosion steel can refer to the above-mentioned embodiments. Since the preparation method of the anti-carbon dioxide corrosion steel adopts part or all of the technical solutions of the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here.

[0072] The application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not to limit the scope of the application. The experimental methods not specified in the following examples are generally determined according to the national standards. If there is no corresponding national standard, the international standard, the conventional condition, or the condition suggested by the manufacturer is used.

[0073] Table 1 Chemical composition of the steel plate for resisting carbon dioxide corrosion

[0074]

[0075]

[0076] Table 2 Rolling process parameters of the steel plate for resisting carbon dioxide corrosion

[0077]

[0078] Table 3 Heat treatment process parameters of the steel plate for resisting carbon dioxide corrosion

[0079]

[0080]

[0081] Table 4 Performance results of the steel plate for resisting carbon dioxide corrosion

[0082] Serial number Yield strength / MPa Tensile strength / MPa Charpy impact energy at -20°C / J CO2 corrosion rate / mm / a Example 1 583 610 130 0.038 Example 2 568 607 134 0.042 Example 3 593 623 150 0.037 Example 4 592 620 128 0.048 Example 5 585 615 137 0.045 Example 6 584 612 138 0.046 Comparative Example 1 523 589 78 0.068 Comparative Example 2 517 568 90 0.078 Comparative Example 3 532 590 95 0.073 Comparative Example 4 534 586 102 0.084 Comparative Example 5 528 592 98 0.085

[0083] From Examples 1-6, the above-mentioned steel plate for resisting carbon dioxide corrosion does not add precious metal elements such as Cu, Ni, Ti, etc., and has moderate Cr content and low production cost. The yield strength is ≥550 MPa, the tensile strength is ≥600 MPa, the Charpy impact energy at -20℃ is ≥120 J, the increase in strength expands the application range. Under the conditions of temperature 20℃-120℃, CO2 partial pressure ≥2 MPa, liquid phase flow rate 1.0 m / s-2.5 m / s, Cl - concentration 10000 mg / L, the carbon dioxide corrosion rate is below 0.05 mm / a, the steel plate still has strong resistance to carbon dioxide corrosion under the service condition of high carbon dioxide partial pressure, and the service period and safety of the steel plate are improved.

[0084] From Comparative Examples 1-5, the steel plate for resisting carbon dioxide corrosion does not use the chemical composition of the examples, the yield strength is below 550 MPa, the tensile strength is not lower than 600 MPa, the Charpy impact energy at -20℃ is below 120 J, and the carbon dioxide corrosion rate is above 0.05 mm / a. Compared with the examples, the steel plate has weak resistance to carbon dioxide corrosion under the same service condition, and cannot meet the use requirements of severe service environment.

[0085] The foregoing detailed description of the application has been presented for purposes of illustration and description. Various modifications and changes can be made to these embodiments without departing from the spirit and scope of the application. It is intended that the scope of the application should not be limited by the particular representative embodiments described above.

Claims

1. A steel for resisting corrosion by carbon dioxide, characterized by, The chemical composition of the steel consists of: C, Cr, Mn, Nb, Si, P, S and Fe; wherein, The content of C is 0.05wt%-0.15wt%, the content of Cr is 1wt%-3wt%, the content of Mn is 1wt%-1.5wt%, the content of Nb is 0.025wt%-0.055wt%, the content of Si is 0.2wt%-0.3wt%, the content of P is ≤0.008wt%, the content of S is ≤0.002wt%, and the balance is Fe; The corrosion rate of the steel is ≤0.05mm / a in an environment with a CO2 partial pressure ≥2MPa; The yield strength of the steel is ≥550MPa, the tensile strength of the steel is ≥600MPa, and the impact energy of the steel at-20℃ is ≥120J; The preparation method of the carbon dioxide corrosion resistant steel comprises: heating the casting blank at a first set temperature; rolling the heated casting blank to obtain a hot-rolled plate; wherein the rolling comprises: coarsely rolling the heated casting blank at a first set rough rolling temperature and a first set finish rolling temperature; finely rolling the coarsely rolled casting blank at a second set rough rolling temperature and a second set finish rolling temperature; heat treating the hot-rolled plate to obtain a carbon dioxide corrosion resistant steel; wherein the heat treatment comprises: quenching the hot-rolled plate at a second set temperature; tempering the quenched hot-rolled plate at a third set temperature; The second set temperature is 880℃-920℃; The third set temperature is 580℃-620℃; The first set temperature is 1200℃-1250℃; The first set rough rolling temperature is 1200℃-1250℃, and the first set finish rolling temperature is 980℃-1040℃; The second set rough rolling temperature is 830℃-850℃, and the second set finish rolling temperature is 770℃-810℃.

2. Steel according to claim 1, characterized in that In the chemical composition of the steel, the content of C is 0.07wt%-0.08wt%, the content of Cr is 1.5wt%-2.1wt%, the content of Mn is 1wt%-1.1wt%, the content of Nb is 0.035wt%-0.04wt%, and the content of Si is 0.2wt%-0.21wt%.

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