A hydrogen embrittlement resistant pipeline steel and a method of making and using the same

Abstract

The application relates to the technical field of steel production, in particular to a hydrogen embrittlement resistant pipeline steel and a preparation method and application thereof. The metallographic structure of the pipeline steel comprises a tempered sorbite structure and nano precipitate particles; the tempered sorbite structure comprises a ferrite matrix and carbide; the grain size of the ferrite is greater than or equal to 10 levels, and the volume fraction of the carbide is less than or equal to 10%; the diameter of the nano precipitate particles is less than or equal to 20 nm. The application solves the technical problem that the existing pipeline steel is prone to hydrogen damage in a high-pressure hydrogen environment, avoids the contradiction between high strength and hydrogen embrittlement resistance, and makes the hydrogen conveying pipeline steel have high strength, high toughness, low hardness and excellent hydrogen embrittlement resistance, so that the hydrogen conveying pipeline steel can meet the use requirements of high-pressure (greater than or equal to 10 MPa) hydrogen conveying.

Description

Technical Field

[0001] This application relates to the field of steel preparation technology, and in particular to a hydrogen embrittlement resistant pipeline steel, its preparation method and application. Background Technology

[0002] During hydrogen transportation and use, metallic materials that come into contact with hydrogen may suffer hydrogen damage and subsequently fail. Hydrogen damage refers to the phenomenon where the mechanical properties of a metal change due to the presence of hydrogen or the reaction of certain components of the metal with hydrogen.

[0003] Existing pipeline steel materials are susceptible to hydrogen damage in high-pressure hydrogen environments, which reduces the toughness or plasticity of the material and makes it prone to cracking or brittle fracture. Summary of the Invention

[0004] This application provides a hydrogen-resistant pipeline steel, its preparation method, and its application, to solve the technical problem that existing pipeline steel is prone to hydrogen damage in a high-pressure hydrogen environment.

[0005] Firstly, this application provides a hydrogen embrittlement resistant pipeline steel, wherein the metallographic structure of the pipeline steel comprises: tempered sorbite and nano-precipitate particles; wherein,

[0006] The tempered sorbite microstructure comprises a ferrite matrix and carbides; wherein the grain size of the ferrite is ≥10 and the volume fraction of the carbides is ≤10%;

[0007] The diameter of the nanoprecipitate particles is ≤20nm.

[0008] Optionally, the nanoprecipitate particles include at least one of the following: Nb / C particles and V / C particles.

[0009] Optionally, the chemical composition of the pipeline steel includes:

[0010] C, Si, Mn, P, S, Al, Nb, V, Ti, Ni, Cr, Cu, and Fe; among which,

[0011] The C content is 0.05 wt% to 0.07 wt%, the Si content is 0.10 wt% to 0.30 wt%, the Mn content is 1.30 wt% to 1.50 wt%, the P content is ≤0.006 wt%, the S content is ≤0.0006 wt%, the Alt content is 0.01 wt% to 0.05 wt%, the Nb content is 0.03 wt% to 0.05 wt%, the V content is 0.03 wt% to 0.04 wt%, the Ti content is 0.005 wt% to 0.020 wt%, the Ni content is ≤0.25 wt%, the Cr content is 0.15 wt% to 0.25 wt%, and the Cu content is ≤0.25 wt%.

[0012] Optionally, the non-metallic inclusions in the pipeline steel include:

[0013] Non-metallic inclusions are categorized into Class A, Class B, Class C, and Class D; among them,

[0014] The grades of Class A, Class B, Class C, and Class D non-metallic inclusions are all ≤1.0; and,

[0015] The sum of the grades of Class A, Class B, Class C, and Class D non-metallic inclusions is ≤2.5.

[0016] Secondly, this application provides the application of the pipeline steel described in any embodiment of the first aspect in a hydrogen environment with a pressure of ≥10MPa.

[0017] Thirdly, this application provides a method for preparing hydrogen embrittlement resistant pipeline steel, used to prepare the pipeline steel described in any embodiment of the first aspect, the method comprising:

[0018] The slab is heated under a first set temperature condition;

[0019] The heated slab is rolled, and the rolling process parameters are controlled to obtain a hot-rolled plate;

[0020] The hot-rolled plate is subjected to quenching treatment, and the quenching process parameters are controlled.

[0021] The quenched hot-rolled plate is tempered, and the tempering process parameters are controlled to obtain pipeline steel.

[0022] Optionally, the quenching process parameters include: quenching start temperature, quenching end temperature, and quenching rate; wherein,

[0023] The quenching start temperature is 760℃~810℃, the quenching end temperature is 100℃~300℃, and the quenching rate is 36℃ / s~46℃ / s.

[0024] Optionally, the tempering process parameters include: tempering temperature and holding time; wherein,

[0025] The tempering temperature is 450℃~600℃, and the holding time is 30min~50min.

[0026] Optionally, the set temperature is 1150℃~1200℃.

[0027] Optionally, the heated slab is rolled, and the rolling process parameters are controlled to obtain a hot-rolled plate, including:

[0028] Under the second set temperature condition, the heated slab is rough rolled;

[0029] Under a third set temperature condition, the rough-rolled hot-rolled plate is then finish-rolled to obtain a hot-rolled plate; wherein,

[0030] The second set temperature is 980℃~1060℃, and the third set temperature is 820℃~900℃.

[0031] The technical solutions provided in this application have the following advantages compared with the prior art:

[0032] The pipeline steel provided in this application embodiment controls the microstructure of the material to be tempered sorbite with nano-precipitate particles. The tempered sorbite microstructure consists of a ferrite matrix and fine spherical carbides. The ferrite grain size is ≥10, the volume fraction of spherical carbides is ≤10%, and the diameter of the precipitate particles is ≤20nm. In the tempered sorbite microstructure, the ferrite grains are fine, resulting in good strength and toughness, and low hardness; the carbides are highly dispersed, spherical, and finely dispersed, improving low-temperature toughness and reducing hardness. The small size of the nano-precipitate particles not only improves strength but also constructs high-density intracrystalline hydrogen traps, enhancing local hydrogen resistance and forming a buffer zone to prevent H-induced microcracks and improve hydrogen embrittlement resistance. This solves the technical problem of existing pipeline steel being prone to hydrogen damage in high-pressure hydrogen environments and avoids the contradiction between high strength and hydrogen embrittlement resistance. The steel used for this hydrogen transmission pipeline has high strength, high toughness, low hardness, and excellent hydrogen embrittlement resistance, which can meet the requirements for high-pressure (≥10MPa) hydrogen transmission. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic flowchart illustrating a method for preparing hydrogen embrittlement resistant pipeline steel provided in this application embodiment;

[0036] Figure 2 Metallographic microstructure of a hydrogen embrittlement resistant pipeline steel provided in this application embodiment;

[0037] Figure 3A diagram of nano-precipitate particles in a hydrogen embrittlement resistant pipeline steel provided in this application embodiment;

[0038] Figure 4 This is a comparison of slow strain rate tensile curves of a hydrogen embrittlement resistant pipeline steel in air and hydrogen environments, provided in Embodiment 1 of this application; where the black line represents the air environment and the red line represents the hydrogen environment. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has 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., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0041] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0042] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0043] In a first aspect, this application provides a hydrogen embrittlement resistant pipeline steel, the microstructure of which comprises: tempered sorbite and nano-precipitate particles; please refer to Figure 2 ,in,

[0044] The tempered sorbite microstructure comprises a ferrite matrix and carbides; wherein the grain size of the ferrite is ≥10 and the volume fraction of the carbides is ≤10%;

[0045] The diameter of the nanoprecipitate particles is ≤20nm.

[0046] This application provides a high-strength pipeline steel with excellent resistance to hydrogen embrittlement. Specifically, this steel is a carbon steel material for high-pressure hydrogen transmission pipelines. The microstructure of the material is controlled to be tempered sorbite with nano-precipitate particles. The tempered sorbite microstructure consists of a ferrite matrix and fine spherical carbides. The ferrite grain size is ≥10, the proportion of spherical carbides is ≤10%, and the diameter of the precipitate particles is ≤20 nm. The tempered sorbite is an equilibrium microstructure with low internal stress, resulting in good resistance to hydrogen embrittlement. Furthermore, the ferrite grains in the tempered sorbite microstructure are fine, resulting in good strength and toughness, and low hardness; the carbides are highly dispersed, spherical, and finely dispersed, improving low-temperature toughness and reducing hardness. Due to their small size, nano-precipitate particles can both improve strength and construct high-density intracrystalline hydrogen traps, enhancing local hydrogen resistance and forming a buffer zone to prevent H-induced microcracks and improve hydrogen embrittlement resistance. This resolves the contradiction between high strength and hydrogen embrittlement resistance, giving the steel used in this hydrogen transmission pipeline high strength, high toughness, low hardness, and excellent hydrogen embrittlement resistance, meeting the requirements for high-pressure (≥10MPa) hydrogen transmission.

[0047] When the metallographic structure does not meet the above requirements, it will lead to problems such as poor resistance to hydrogen embrittlement. For example, if the metallographic structure is not tempered sorbite, but a hard phase structure such as granular bainite, lath bainite, acicular ferrite or martensite, the dislocation density is high, the internal stress is high, and the hardness is high. This type of structure is very prone to hydrogen embrittlement fracture. If the ferrite grain size in the tempered sorbite structure is larger, hydrogen embrittlement fracture is more likely to occur at the grain boundaries. If there are more and larger carbides in the metallographic structure, stress concentration will occur at the carbides, making hydrogen embrittlement fracture more likely to occur.

[0048] Slow strain rate tensile tests were conducted in a 10 MPa high-pressure hydrogen atmosphere (strain rate ≤ 10). -5 / s), the elongation after fracture and hydrogen embrittlement sensitivity index (HEIδ) of the steel are ≤20%; fatigue life test is conducted in a 10MPa high-pressure hydrogen environment (test frequency ≤1Hz), and the total number of fatigue cycles of the steel is ≥10. 5 Furthermore, the yield strength of this pipeline steel is ≥490MPa, the tensile strength is ≥575MPa, and the yield strength ratio is ≤0.90. This steel combines excellent high strength and resistance to hydrogen embrittlement, making it suitable for high-pressure service conditions with hydrogen pressure ≥10MPa. It can resist hydrogen embrittlement without fracture failure, significantly improving service life and safety, and has good application prospects.

[0049] In some embodiments, the nanoprecipitate particles include at least one of the following: Nb / C particles and V / C particles.

[0050] The nanoprecipitates can be either Nb / C particles or V / C particles, or a mixture of Nb / C particles and V / C particles. The positive effects of Nb / C and V / C particles are as follows: precipitates during the rolling stage can act as pinning and dragging agents, inhibiting austenite grain growth; precipitates during the phase transformation stage can refine the grains, thereby improving strength and constructing high-density intragranular hydrogen traps, reducing the movement of diffusing hydrogen, and enhancing the material's resistance to hydrogen embrittlement, thus resolving the contradiction between high strength and resistance to hydrogen embrittlement.

[0051] In some embodiments, the chemical composition of the pipeline steel includes:

[0052] C, Si, Mn, P, S, Al, Nb, V, Ti, Ni, Cr, Cu, and Fe; among which,

[0053] The C content is 0.05 wt% to 0.07 wt%, the Si content is 0.10 wt% to 0.30 wt%, the Mn content is 1.30 wt% to 1.50 wt%, the P content is ≤0.006 wt%, the S content is ≤0.0006 wt%, the Alt content is 0.01 wt% to 0.05 wt%, the Nb content is 0.03 wt% to 0.05 wt%, the V content is 0.03 wt% to 0.04 wt%, the Ti content is 0.005 wt% to 0.020 wt%, the Ni content is ≤0.25 wt%, the Cr content is 0.15 wt% to 0.25 wt%, and the Cu content is ≤0.25 wt%.

[0054] The positive effects of controlling the carbon content to 0.05% to 0.07% by weight: Carbon enhances the strength of materials through solid solution strengthening, and its content significantly affects strength, hardness, and resistance to hydrogen embrittlement. Excessive carbon content may lead to severe center segregation, deterioration of the banded structure, increased carbide ratio, and higher strength and hardness values, resulting in poor resistance to hydrogen embrittlement. Conversely, insufficient carbon content may lead to lower strength properties. Specifically, the carbon content can be 0.05% by weight, 0.06% by weight, or 0.07% by weight, etc.

[0055] The positive effects of controlling the Si content to be 0.10 wt% to 0.30 wt% include: the solid solution strengthening effect of Si, combined with low C and low Mn content, which not only achieves high strength but also provides a stable tempered sorbite structure and excellent resistance to hydrogen embrittlement. Specifically, the Si content can be 0.10 wt%, 0.20 wt%, 0.30 wt%, etc.

[0056] The positive effects of controlling the Mn content to 1.30%–1.50% by weight: Mn is an element prone to segregation. If the Mn content is too high, it may lead to problems such as high strength, high hardness, poor central segregation, deterioration of banded structure, and poor resistance to hydrogen embrittlement in the steel. If the Mn content is too low, it may lead to insufficient strength properties in the steel. Specifically, the Mn content can be 1.30% by weight, 1.40% by weight, 1.50% by weight, etc.

[0057] The positive effects of controlling the P content to ≤0.006 wt% and the S content to ≤0.0006 wt% are as follows: P and S are impurity elements in steel, and they are prone to segregation, affecting the internal quality of continuously cast billets. Furthermore, they tend to agglomerate at grain boundaries. If the P and S content is too high, elemental agglomeration will occur at grain boundaries to a certain extent, leading to a large accumulation of hydrogen at the grain boundaries, which easily causes brittle fracture and poor resistance to hydrogen embrittlement. Specifically, the P content can be 0.006 wt%, 0.005 wt%, etc.; and the S content can be 0.0006 wt%, 0.0005 wt%, etc.

[0058] The positive effects of controlling the Al content to 0.01% to 0.05% by weight include: Al is used for deoxidation in steelmaking and has a certain effect on refining grains. Simultaneously, Al can fix free nitrogen, reducing nitrogen gas content. If the Al content is too high, it can become inclusions to some extent, affecting low-temperature toughness and resistance to hydrogen embrittlement; if the Al content is too low, it can lead to incomplete deoxidation, inclusions, and poor billet quality. Specifically, the Al content can be 0.01% by weight, 0.02% by weight, 0.03% by weight, 0.04% by weight, 0.05% by weight, etc.

[0059] The positive effects of Nb content of 0.03 wt%–0.05 wt%, V content of 0.03 wt%–0.04 wt%, and Ti content of 0.005 wt%–0.020 wt%: Nb, V, and Ti elements can produce a large number of nano-precipitate particles. Please refer to [link to relevant documentation]. Figure 3 This process constructs intracrystalline hydrogen traps to pin hydrogen atoms, inhibiting the migration of hydrogen atoms to defects such as dislocations or inclusions, thereby forming a buffer zone that passivates microcracks and improves resistance to hydrogen embrittlement. Specifically, the Nb content can be 0.03 wt%, 0.04 wt%, 0.05 wt%, etc., the V content can be 0.03 wt%, 0.04 wt%, 0.035 wt%, etc., and the Ti content can be 0.005 wt%, 0.01 wt%, 0.015 wt%, 0.020 wt%, etc.

[0060] The positive effects of controlling the Ni content to ≤0.25 wt% include: Ni is an austenitic stabilizing element that can lower the γ→α transformation temperature and effectively improve the low-temperature toughness of pipeline steel. Ni can improve the strength and low-temperature crack-arresting toughness of steel through solid solution strengthening. However, excessive Ni will significantly increase costs. Specifically, the Ni content can be 0.025 wt%, 0.020 wt%, 0.015 wt%, etc.

[0061] The positive effects of controlling the Cr content to 0.15 wt% to 0.25 wt% include: Cr is effective in improving the tensile strength of pipeline steel and can significantly reduce the yield strength ratio of the material. However, higher Cr content is detrimental to weldability and resistance to hydrogen embrittlement. Specifically, the Cr content can be 0.15 wt%, 0.20 wt%, 0.25 wt%, etc.

[0062] The positive effects of controlling the Cu content to ≤0.25 wt% include: Cu can improve the strength and toughness of steel plates. Specifically, the Cu content can be 0.25 wt%, 0.20 wt%, 0.15 wt%, etc.

[0063] In some embodiments, the non-metallic inclusions in the pipeline steel include:

[0064] Non-metallic inclusions are categorized into Class A, Class B, Class C, and Class D; among them,

[0065] The grades of Class A, Class B, Class C, and Class D non-metallic inclusions are all ≤1.0; and,

[0066] The sum of the grades of Class A, Class B, Class C, and Class D non-metallic inclusions is ≤2.5.

[0067] The positive effects of setting grade requirements for non-metallic inclusions in pipeline steel include: ensuring good internal quality of the slab, reducing deadly hydrogen traps, and improving the material's resistance to hydrogen embrittlement. When inclusions do not meet the above requirements of this invention, they become deadly hydrogen traps, leading to hydrogen embrittlement and poor resistance to hydrogen embrittlement. For example, the more inclusions there are and the larger their size, the easier it is for hydrogen embrittlement fracture to occur at the inclusion sites.

[0068] Secondly, this application provides the application of the pipeline steel described in any embodiment of the first aspect in a hydrogen environment with a pressure of ≥10MPa.

[0069] Slow strain rate tensile tests were conducted in a 10 MPa high-pressure hydrogen atmosphere (strain rate ≤ 10). -5 / s), the elongation after fracture and hydrogen embrittlement sensitivity index (HEIδ) of the steel are ≤20%; fatigue life test is conducted in a 10MPa high-pressure hydrogen environment (test frequency ≤1Hz), and the total number of fatigue cycles of the steel is ≥10. 5 Furthermore, the yield strength of this pipeline steel is ≥490MPa, the tensile strength is ≥575MPa, and the yield strength ratio is ≤0.90. This steel combines excellent high strength and resistance to hydrogen embrittlement, making it suitable for high-pressure service conditions with hydrogen pressure ≥10MPa. It can resist hydrogen embrittlement without fracture failure, significantly improving service life and safety, and has good application prospects.

[0070] Thirdly, this application provides a method for preparing hydrogen embrittlement resistant pipeline steel, used to prepare the pipeline steel described in any embodiment of the first aspect. Please refer to [link to relevant documentation]. Figure 1 The method includes:

[0071] S1. Under the condition of the first set temperature, the slab is heated;

[0072] S2. The heated slab is rolled, and the rolling process parameters are controlled to obtain a hot-rolled plate;

[0073] S3. The hot-rolled plate is subjected to quenching treatment, and the quenching process parameters are controlled.

[0074] S4. The quenched hot-rolled plate is tempered, and the tempering process parameters are controlled to obtain pipeline steel.

[0075] Based on slabs with the above-mentioned chemical composition, and by designing heating, rolling, quenching, and tempering process parameters, high-strength pipeline steel with excellent resistance to hydrogen embrittlement was prepared.

[0076] In some embodiments, the quenching process parameters include: quenching start temperature, quenching end temperature, and quenching rate; wherein,

[0077] The quenching start temperature is 760℃~810℃, the quenching end temperature is 100℃~300℃, and the quenching rate is 36℃ / s~46℃ / s.

[0078] The positive effects of controlling the quenching start temperature to 760℃~810℃, the quenching end temperature to 100℃~300℃, and the quenching rate to 36℃ / s~46℃ / s are: obtaining ideal phase transformation products (tempered sorbite structure + nano-precipitate particles), which not only results in fine grains but also ensures the strength and toughness of the steel. If the above values ​​are controlled too high, the austenite grains may be too large, or the quenched structure may be uneven, leading to poor low-temperature toughness and resistance to hydrogen embrittlement. If the above values ​​are controlled too low, complete austenitization may not be achieved, resulting in a poor quenched structure and poor low-temperature toughness and resistance to hydrogen embrittlement. Specifically, the quenching start temperature can be 760℃, 780℃, 800℃, 810℃, etc.; the quenching end temperature can be 100℃, 150℃, 200℃, 250℃, 300℃, etc.; and the quenching rate can be 36℃ / s, 38℃ / s, 40℃ / s, 42℃ / s, 44℃ / s, 4℃ / s, etc.

[0079] In some embodiments, the tempering process parameters include: tempering temperature and holding time; wherein,

[0080] The tempering temperature is 450℃~600℃, and the holding time is 30min~50min.

[0081] The positive effects of controlling the tempering temperature to 450℃~600℃ and the holding time to 30min~50min are: obtaining ideal phase transformation products (tempered sorbite structure + nano-precipitate particles). If the above values ​​are too high, it may lead to coarse ferrite grains, high carbide volume fraction, and large precipitate size, resulting in poor low-temperature toughness and resistance to hydrogen embrittlement. If the above values ​​are too low, the quenched structure may still exist, the hardness may be too high, and the number of precipitates may be too small, resulting in poor low-temperature toughness and resistance to hydrogen embrittlement. Specifically, the tempering temperature can be 450℃, 500℃, 600℃, etc., and the holding time can be 30min, 40min, 50min, etc.

[0082] In some embodiments, the set temperature is 1150°C to 1200°C.

[0083] "Set temperature" refers to the heating temperature. The positive effects of controlling this heating temperature are: low-temperature heating inhibits austenite grain growth, resulting in fine and uniform grains. If the heating temperature is too high, it can lead to coarse austenite grains, ultimately affecting the resistance to hydrogen embrittlement. Specifically, this heating temperature can be 1150℃, 1170℃, 1190℃, 1200℃, etc.

[0084] In some embodiments, the heated slab is rolled, and the rolling process parameters are controlled to obtain a hot-rolled plate, including:

[0085] Under the second set temperature condition, the heated slab is rough rolled;

[0086] Under a third set temperature condition, the rough-rolled hot-rolled plate is then finish-rolled to obtain a hot-rolled plate; wherein,

[0087] The second set temperature is 980℃~1060℃, and the third set temperature is 820℃~900℃.

[0088] "Second set temperature" refers to the roughing rolling temperature, and "Third set temperature" refers to the finishing rolling temperature. Controlling the roughing rolling temperature to 980℃~1060℃ and the finishing rolling temperature to 820℃~900℃ has the following positive effects: it allows for sufficient recrystallization of austenite grains, refines the grains, and accumulates dislocation and phase transformation energy, ensuring that subsequent ferrite phase transformation fully refines the grains and improves resistance to hydrogen embrittlement. If the roughing and finishing rolling temperatures are not within these ranges, it may, to some extent, lead to larger austenite grains, poor deformation accumulation, and coarser ferrite grains in subsequent phase transformations, ultimately affecting resistance to hydrogen embrittlement. Specifically, the roughing rolling temperature can be 980℃, 1000℃, 1200℃, 1400℃, 1600℃, etc., and the finishing rolling temperature can be 820℃, 840℃, 860℃, 880℃, 900℃, etc.

[0089] The preparation method of this hydrogen embrittlement resistant pipeline steel is based on the above-mentioned hydrogen embrittlement resistant pipeline steel. The specific steps of this pipeline steel can be referred to the above embodiments. Since the preparation method of this pipeline steel adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0090] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0091] Table 1 Metallographic structure of hydrogen embrittlement resistant pipeline steel

[0092]

[0093] Table 2 Chemical composition (wt%) of hydrogen embrittlement resistant pipeline steel

[0094]

[0095]

[0096] Table 3. Grades of non-metallic inclusions in hydrogen embrittlement resistant pipeline steel.

[0097]

[0098]

[0099] Table 4. Process parameters for preparing hydrogen embrittlement resistant pipeline steel

[0100]

[0101] Table 5 Statistical results of the performance of hydrogen embrittlement resistant pipeline steel

[0102]

[0103]

[0104] As shown in Tables 1-5 above, the high-strength hydrogen pipeline steel materials prepared in Examples 1-7 of this application all exhibit high strength, high toughness, low yield strength ratio, and good resistance to hydrogen embrittlement, which significantly improves the service life and safety of the materials under high-pressure hydrogen environments of ≥10MPa.

[0105] The metallographic microstructure of the high-strength hydrogen pipeline steel prepared in Example 1 of this application is as follows: Figure 2 As shown, by Figure 2 It can be seen that the metallographic structure is tempered sorbite, with fine ferrite grains, few and small-sized spheroidized carbides, no obvious banded structure, and no other hard phases. The high-density nano-precipitates in the high-strength hydrogen pipeline steel prepared in Example 1 are as follows: Figure 3 As shown, by Figure 3 It can be seen that the microstructure contains a large number of dispersed, high-density, nanoscale precipitate particles. The slow strain rate tensile curves of the high-strength hydrogen pipeline steel prepared in Example 1 under air and hydrogen environments are compared. Figure 4 As shown, by Figure 4 It can be seen that the decrease in elongation δ after fracture is not significant, the tendency for hydrogen embrittlement is not obvious, and it has excellent resistance to hydrogen embrittlement. The disadvantage of the comparative example is that it is fundamentally different from the present invention in terms of chemical composition, metallographic structure, and process parameters. The ferrite grain size, carbide volume fraction, and precipitate particle diameter of the steel are fundamentally different from those of the embodiments of this application, resulting in very poor resistance to hydrogen embrittlement of the comparative example material under high-pressure hydrogen environment.

[0106] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A hydrogen-embrittlement-resistant pipeline steel, characterized in that, The microstructure of the pipeline steel includes: tempered sorbite and nano-precipitate particles; wherein, The tempered sorbite microstructure comprises a ferrite matrix and carbides; wherein the grain size of the ferrite is ≥10 and the volume fraction of the carbides is ≤10%; The diameter of the nanoprecipitate particles is ≤20nm; The chemical composition of the pipeline steel includes: C content of 0.05 wt% to 0.07 wt%, Si content of 0.10 wt% to 0.30 wt%, Mn content of 1.30 wt% to 1.50 wt%, P content of ≤0.006 wt%, S content of ≤0.0006 wt%, Al content of 0.01 wt% to 0.05 wt%, Nb content of 0.03 wt% to 0.05 wt%, V content of 0.03 wt% to 0.04 wt%, Ti content of 0.005 wt% to 0.020 wt%, Ni content of ≤0.25 wt%, Cr content of 0.15 wt% to 0.25 wt%, and Cu content of ≤0.25 wt%. The preparation process of the hydrogen embrittlement resistant pipeline steel includes: quenching the hot-rolled plate, and tempering the quenched hot-rolled plate to obtain the pipeline steel. The quenching start temperature is 760℃~810℃, the quenching end temperature is 100℃~300℃, the quenching rate is 36℃ / s~46℃ / s, the tempering temperature is 450℃~600℃, and the tempering holding time is 30min~50min. The non-metallic inclusions in the pipeline steel include: Non-metallic inclusions are categorized into Class A, Class B, Class C, and Class D; among them, The grades of Class A, Class B, Class C, and Class D non-metallic inclusions are all ≤1.0; and, The sum of the grades of Class A, Class B, Class C, and Class D non-metallic inclusions is ≤2.

5.

2. The pipeline steel according to claim 1, characterized in that, The nanoprecipitate particles include at least one of the following: Nb / C particles and V / C particles.

3. The application of the pipeline steel according to any one of claims 1-2 in a hydrogen environment with a pressure of ≥10MPa.

4. A method for preparing hydrogen embrittlement resistant pipeline steel, characterized in that, The method for preparing pipeline steel according to any one of claims 1-2 comprises: The slab is heated under a first set temperature condition; The heated slab is rolled to obtain a hot-rolled plate; The hot-rolled plate is subjected to quenching treatment; The quenched hot-rolled plate is tempered to obtain pipeline steel; The first set temperature is 1150℃~1200℃; The heated slab is rolled to obtain a hot-rolled plate, including: Under the second set temperature condition, the heated slab is rough rolled; Under the condition of the third set temperature, the hot-rolled plate after rough rolling is finished rolled to obtain a hot-rolled plate; wherein, the second set temperature is 980℃~1060℃, and the third set temperature is 820℃~900℃.

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