An X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement and its manufacturing method

Abstract

This invention relates to an X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement and its manufacturing method. The chemical composition of the pipeline steel plate, by mass percentage, is: C 0.03%–0.04%, Si 0.10%–0.11%, Mn 0.50%–0.52%, P≤0.004%, S≤0.001%, Al 0.015%–0.02%, Ni 0.20%–0.30%, Cr 0.22%–0.27%, Mo 0.22%–0.30%, Cu 0.21%–0.25%, Nb 0.06%–0.08%, V 0.05%–0.07%, Ti 0.028%–0.040%, with the balance being Fe and impurity elements. The advantages are: the yield strength of the pipeline steel plate is ≥690 MPa; the hydrogen-induced cracking performance indicators CSR, CLR, and CTR are all 0.

Description

Technical Field

[0001] This invention belongs to the field of special purpose pipeline steel manufacturing technology, and particularly relates to an X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement and its manufacturing method. Background Technology

[0002] Hydrogen transportation is a crucial link in hydrogen energy utilization, and safe and efficient hydrogen transportation technology is a prerequisite for the large-scale commercial development of hydrogen energy. Long-distance hydrogen transportation via pipelines has significant economic value, offering advantages such as large transport capacity, low energy consumption, and low cost. However, during hydrogen transportation and use, metallic materials in contact with hydrogen are susceptible to hydrogen damage and subsequent failure. Hydrogen damage refers to the phenomenon where the mechanical properties of metals change due to the presence of hydrogen or the reaction of certain components within the metal with hydrogen. Existing pipeline steel materials are susceptible to hydrogen damage under high-pressure hydrogen environments, leading to reduced toughness or plasticity and increased susceptibility to cracking or brittle fracture. Currently, existing hydrogen transportation pipelines are all made of X52 or lower grade steel, with limited transport capacity, hindering the development of higher-pressure hydrogen transportation pipelines.

[0003] In the prior art, patent application number 202310743976.7 discloses a method for producing pipeline steel for TMCP hydrogen doping and transportation. Besides possessing the mechanical properties expected of X52 grade pipeline steel, the steel plate also exhibits good hydrogen environment compatibility. This method controls the Si content to 0.12%-0.3%. Excessive Si content reduces the solubility of Mo in the steel, inhibiting Mo's role in promoting (Mo, V)C precipitation, ultimately reducing the function of VC as a hydrogen trap. Furthermore, excessive Si content significantly reduces the weldability of the steel, making it difficult to meet the welding requirements for pipeline steel, resulting in high welding difficulty. This method also controls the Mn content to 0.95%-1.05%, which easily combines with S to form MnS inclusions, increasing local hydrogen pressure and becoming a site prone to hydrogen embrittlement. Furthermore, the method produces steel plates with a yield strength of up to 457 MPa, and only examines the hydrogen embrittlement sensitivity of the material under a hydrogen pressure of 6.3 MPa. In contrast, the steel plates produced by this method have a yield strength of over 690 MPa, and examine the hydrogen embrittlement sensitivity of the material under a hydrogen pressure of 14 MPa, which is better able to meet future demands for high strength and high pressure.

[0004] Patent application number 202111145706.3 discloses a marine-grade X80 pipeline steel resistant to hydrogen-induced cracking and its manufacturing method. The steel plate achieves the mechanical properties of X80 steel grade. After immersion testing using the NACE standard test method, the hydrogen-induced cracking sensitivity parameters (crack sensitivity rate CSR, crack length sensitivity rate CLR, and crack thickness sensitivity rate CTR) are all 0. This method controls the Mn content at 1.75%-1.95%, which easily combines with S to form MnS inclusions, increasing local hydrogen pressure and becoming a potential site for hydrogen embrittlement. Furthermore, this method only performs HIC resistance testing and does not conduct slow tensile testing under hydrogen conditions, resulting in insufficient testing items under hydrogen environmental conditions.

[0005] Patent application number 202210455726.9 discloses a pipeline steel plate with excellent resistance to hydrogen-induced cracking and its preparation method. The steel plate achieves a yield strength of X70 and exhibits excellent resistance to hydrogen-induced cracking. The method controls the Mn content to 0.8%-1.8%, which easily combines with S to form MnS inclusions, increasing local hydrogen pressure and becoming a site prone to hydrogen embrittlement. The steel plate microstructure includes 8%-10% pearlite, which is highly sensitive to hydrogen embrittlement and easily undergoes hydrogen embrittlement in high-pressure hydrogen environments. Furthermore, this method does not perform slow tensile testing under hydrogen conditions, resulting in insufficient testing under hydrogen environmental conditions and making it difficult to ensure the safety of the material in hydrogen environments.

[0006] Patent application number 201711181735.9 discloses a method for producing X80 grade pipeline steel resistant to hydrogen-induced cracking, resulting in steel plates with excellent resistance to hydrogen-induced cracking. This method controls the Si content to 0.20%-0.23%. Excessive Si content reduces the solubility of Mo in the steel, inhibiting Mo's role in promoting (Mo,V)C precipitation, ultimately reducing the function of VC as a hydrogen trap. Furthermore, excessive Si content significantly reduces the weldability of the steel, making it difficult to meet the welding requirements for pipeline steel and increasing the difficulty of welding the steel plates. In addition, this method only performs HIC resistance tests, neglecting slow tensile tests under hydrogen conditions. The testing items under hydrogen conditions are insufficient, making it difficult to ensure the safety of the material in a hydrogen environment.

[0007] Patent application number 202211172545.1 discloses an economical hydrogen transmission pipeline steel and its production method, with a yield strength of 298-507 MPa for the steel plate. This method controls the Mn content to 0.53%-1.19%. Excessive Mn content easily combines with S to form MnS inclusions, increasing local hydrogen pressure and becoming a site prone to hydrogen embrittlement. The steel plate does not contain V, failing to effectively utilize V to form hydrogen traps and reduce the material's hydrogen embrittlement sensitivity. Furthermore, this method does not specify the slow tensile test conditions under hydrogen conditions, such as hydrogen pressure and strain rate, while the steel plate produced by this method was tested for hydrogen embrittlement sensitivity under 14 MPa hydrogen pressure, better meeting future demands for high strength and high pressure.

[0008] Patent application number 202310634479.3 discloses an acid-corrosion-resistant pipeline steel plate and its preparation method, employing flexible rolling technology to produce X65 and X70 grade acid-resistant pipeline steel. However, this method does not add Nb or Ti elements, failing to effectively utilize TiC and Nb to form hydrogen traps. Furthermore, the absence of Mo makes it difficult to utilize Mo to promote VC precipitation, thus failing to effectively utilize VC to form hydrogen traps and reduce the material's hydrogen embrittlement sensitivity. In addition, this method does not examine the material's mechanical properties in a hydrogen environment, making it difficult to directly apply to hydrogen-exposed environments.

[0009] Patent application number 202211110087.9 discloses a high-toughness, high-corrosion-resistant pipeline steel and its production method, producing X80 grade corrosion-resistant pipeline steel. This method controls the Mn content to 1.45%-1.55%. Excessive Mn content easily combines with S to form MnS inclusions, increasing local hydrogen pressure and becoming a site prone to hydrogen embrittlement. Furthermore, the steel plate does not contain added V, failing to effectively utilize V to form hydrogen traps to reduce the material's hydrogen embrittlement sensitivity. In addition, this method does not examine the material's mechanical properties in a hydrogen environment, making it difficult to directly apply to hydrogen-exposed environments. Summary of the Invention

[0010] The purpose of this invention is to provide an X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement and a manufacturing method thereof. The pipeline steel has excellent resistance to hydrogen embrittlement, with a yield strength ≥690MPa and a tensile strength ≥760MPa, and can be directly used in hydrogen-contaminated environments.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] An X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement, wherein the chemical composition of the pipeline steel plate by mass percentage is:

[0013] C 0.03%–0.04%, Si 0.10%–0.11%, Mn 0.50%–0.52%, P≤0.004%, S≤0.001%, Al 0.015%–0.02%, Ni 0.20%–0.30%, Cr 0.22%–0.27%, Mo 0.22%–0.30%, Cu 0.21%–0.25%, Nb 0.06%–0.08%, V 0.05%–0.07%, Ti 0.028%–0.040%, with the balance being Fe and unavoidable impurity elements;

[0014] The microstructure of the steel plate consists entirely of acicular ferrite, with NbC, TiC, and VC dispersed in the matrix.

[0015] The pipeline steel plate has a yield strength ≥690MPa; tensile strength ≥760MPa; impact energy at -20℃ ≥200J; according to standard GBT8650-2015, the hydrogen-induced cracking performance indicators CSR, CLR, and CTR are all 0 in solution A; after being charged with hydrogen for 12 hours in 0.5mol / L sulfuric acid + 2g / L thiourea solution, a slow strain rate tensile test (SSRT) is performed at a strain rate of 1e. -5 / s, the elongation after fracture of the specimen is greater than 85% under air conditions; a slow strain rate tensile test was conducted under a high-pressure hydrogen environment of 14MPa, with a strain rate of 1e -5 / s, the elongation after fracture of the sample is greater than 80% of that in air.

[0016] The roles and ranges of the main alloying elements in X100 grade pipeline steel plates, which have excellent resistance to hydrogen embrittlement, are explained below:

[0017] Carbon (C): C is the second most important element in steel after Fe, directly affecting the strength, plasticity, toughness, and weldability of steel. C significantly improves the strength of steel through solid solution strengthening and precipitation strengthening, but increasing the C content negatively impacts the plasticity, toughness, and weldability. Furthermore, excessively high C content can cause center segregation at the center of the steel plate thickness, leading to the formation of hydrogen embrittlement-sensitive structures such as pearlite, granular bainite, and martensite, thus reducing the material's resistance to hydrogen embrittlement. Therefore, the C content range is set at 0.03%–0.04%.

[0018] Silicon (Si): Si is an important reducing agent and deoxidizer in steelmaking. It dissolves in ferrite and austenite, increasing the hardness and strength of steel. Increasing the Si content can reduce the tendency of Fe3C precipitation, allowing more C and V to precipitate and form hydrogen traps (VC), thus reducing the material's hydrogen embrittlement sensitivity. Excessive Si content will significantly reduce the plasticity, toughness, and weldability of steel. Furthermore, excessive Si will reduce the solubility of Mo in steel, inhibiting Mo's role in promoting (Mo,V)C precipitation. Therefore, the Si content range is set at 0.10%–0.11%.

[0019] Manganese (Mn): Mn improves the hardenability of steel, which is beneficial to its strength. Because Mn is relatively inexpensive and has infinite solid solubility with Fe, its impact on plasticity is relatively small while increasing steel strength. Therefore, Mn is widely used as a strengthening element in steel. Excessive Mn content exacerbates segregation in continuously cast billets, increases the grade of banded microstructure in steel plates, and worsens microstructure uniformity, negatively impacting the steel plate's resistance to lamellar tearing, plasticity, low-temperature toughness, and weldability. Furthermore, it readily combines with sulfur to form MnS inclusions, increasing local hydrogen pressure and becoming a common site for hydrogen embrittlement. Therefore, the Mn content range is set at 0.50%–0.52%.

[0020] Phosphorus (P): P is introduced into steel from ores and, like sulfur (S), is a harmful element. Although P can increase the strength and hardness of steel, the formation of P-containing segregated banded structures in steel can significantly reduce plasticity, impact toughness, and resistance to hydrogen embrittlement. Therefore, the P content should not exceed 0.004%.

[0021] Sulfur (S): S originates from steelmaking ores and fuel coke, and is one of the most common harmful elements in steel, negatively impacting its ductility, toughness, weldability, and corrosion resistance. S readily forms MnS inclusions with Mn, increasing local hydrogen pressure and becoming a common site for hydrogen embrittlement. Therefore, the S content should not exceed 0.001%.

[0022] Aluminum (Al): Al is added to steel as a deoxidizer or alloying element, and its deoxidizing ability is much stronger than that of silicon and manganese. The main role of aluminum in steel is to refine grains and fix nitrogen in the steel, thereby significantly improving the impact toughness and reducing the tendency for cold brittleness and aging. Aluminum can also improve the corrosion resistance of steel, especially when used in combination with elements such as molybdenum, copper, silicon, and chromium. The disadvantage of aluminum is that it affects the hot working properties, weldability, and machinability of steel. Therefore, the Al content should be selected within the range of 0.015% to 0.02%.

[0023] Nickel (Ni): Ni stabilizes austenite and improves hardenability. Adding a certain amount of Ni to steel can improve strength, toughness, corrosion resistance, and lower the ductile-brittle transition temperature. Ni-containing steel is generally less prone to overheating, as it can prevent grain growth at high temperatures and maintain a fine-grained structure. However, considering cost factors, the Ni content range of 0.20% to 0.30% is selected.

[0024] Chromium (Cr): Cr can improve the strength, hardness, and wear resistance of steel without making it brittle, but it will reduce elongation and reduction of area. Excessive Cr addition will cause Cr-containing carbides to precipitate and aggregate at the original austenite grain boundaries during welding thermal cycling, severely impairing the low-temperature toughness and weldability of the steel plate. Therefore, a Cr content range of 0.22%–0.27% is selected.

[0025] Molybdenum (Mo): In steel, Mo improves hardenability and hot strength, and inhibits ferrite transformation during the cooling process of steel plates. It increases the dislocation density within the grains over a wider cooling range, thereby enhancing the strain hardening capacity of the steel plate. Adding Mo can improve the material's resistance to hydrogen embrittlement by forming hydrogen traps through (Mo,V)C. However, excessive Mo content is detrimental to weldability and increases alloy costs. Therefore, a Mo content range of 0.22%–0.30% is selected.

[0026] Copper (Cu): Cu can improve the strength of steel without adversely affecting weldability. At low Cu content, its effect is similar to, but weaker than, that of nickel. High Cu content is detrimental to hot deformation processing, leading to copper embrittlement during this process. Therefore, a Cu content range of 0.21%–0.25% is selected.

[0027] Niobium (Nb): Nb is one of the most important microalloying elements. It partially dissolves in the solid solution, providing solid solution strengthening. When present as carbide, nitride, and oxide particles, it provides precipitation strengthening. Furthermore, Nb carbonitrides are excellent hydrogen traps, reducing the diffusion rate of hydrogen atoms in steel and effectively improving the material's resistance to hydrogen embrittlement. Trace amounts of Nb can increase the strength of steel without affecting its plasticity or toughness. Due to its grain-refining effect, it can improve the impact toughness of steel and lower its brittle transition temperature. During controlled rolling, solid-solution Nb significantly increases the recrystallization temperature of steel, allowing the rolling process to be completed within a higher temperature range, thereby reducing the internal stress of the steel plate. Therefore, an Nb content range of 0.06%–0.08% was selected.

[0028] Vanadium (V): V has a strong affinity for C, N, and O, forming corresponding stable compounds. In steel, V mainly exists in the form of carbides, which refine the microstructure and grain size, improve strength and toughness, enhance weldability, and reduce overheating sensitivity. V carbonitrides are also hydrogen traps, effectively improving the material's resistance to hydrogen embrittlement. Excessive V content results in larger V-containing precipitates, which is detrimental to the strain hardening ability of the steel plate and worsens the impact toughness of the weld heat-affected zone. Therefore, a V content range of 0.05%–0.07% is selected.

[0029] Titanium (Ti): Ti is a strong carbonitride forming element. Ti-containing precipitates can effectively pin grain boundaries, hinder austenite growth, refine grains, and improve the strength, toughness, and low-temperature toughness of steel plates. Nanoscale Ti-containing precipitates can hinder dislocation movement and improve the strain hardening ability of steel plates. Excessive Ti content can lead to coarsening of the Ti-containing precipitates, negatively impacting performance. Therefore, a Ti content range of 0.028%–0.040% is selected.

[0030] A method for manufacturing X100 grade pipeline steel plates with excellent resistance to hydrogen embrittlement includes smelting, ladle refining, continuous casting, heating, rolling, cooling and tempering heat treatment.

[0031] After the steel plate is rolled, it is directly quenched online. The cooling start temperature is 820-840℃, the cooling rate is controlled at 25-35℃ / s, and the cooling end temperature is controlled at 200-300℃.

[0032] After the steel plate has cooled, it is subjected to tempering treatment at a temperature of 580–620℃ and a holding time of 60–90 minutes.

[0033] The heating process is as follows: the billet after continuous casting is reheated at a temperature of 1150-1250℃ for a total furnace time of 4-6 hours; high-pressure water descaling is performed, and the temperature of the continuously cast billet after descaling is ≥1120℃.

[0034] The rolling process employs a two-stage rolling process. In the first stage, during the recrystallization zone rolling, the final rolling temperature is ≥980℃ and the ratio of intermediate billet thickness to finished steel plate thickness is ≥2. In the second stage, during the non-recrystallization zone rolling, the initial rolling temperature is 910~930℃ and the final rolling temperature is ≥840℃.

[0035] The reasons for the control range of process parameters in the manufacturing method of this pipeline steel plate are as follows:

[0036] The heating temperature of the continuously cast billet is controlled between 1150 and 1250℃, with a total furnace time of 4 to 6 hours. This ensures that the precipitated phases of alloying elements are fully dissolved back into the austenite, maximizing the beneficial effects of inhibiting recrystallization, solid solution strengthening, precipitation strengthening, and grain refinement during subsequent controlled rolling. This prepares the composition and temperature for obtaining the final microstructure. Below the selected temperature and time range, solid solution will be insufficient, affecting the final steel plate strength; above the selected time and temperature range, the original austenite grains in the continuously cast billet are prone to being too coarse, which is detrimental to the control of the steel plate's toughness.

[0037] After the continuously cast billet exits the furnace, it undergoes high-pressure water descaling to ensure the surface quality of the rolled steel plate. After descaling, the temperature is below 1120℃, increasing the rolling load during the rolling stage.

[0038] A two-stage rolling process is adopted. The first stage, recrystallization rolling, is completed before 980℃ to avoid partial recrystallization of austenite, which would result in uneven grain size. The second stage, non-recrystallization rolling, is completed between 840℃ and 930℃. Temperatures above 930℃ cause partial recrystallization in the rolled piece, resulting in uneven grain size. Temperatures below 840℃ make it difficult to guarantee the starting temperature required for subsequent direct accelerated cooling. At this temperature, austenite transforms into polygonal ferrite, and not enough acicular ferrite is produced, which makes it difficult to guarantee the strength of the steel plate. Selecting an intermediate billet with a thickness of not less than twice the thickness of the finished steel plate is to ensure the cumulative reduction in the second stage of rolling, so that the recrystallized austenite grains are fully flattened, which is beneficial to subsequent microstructure transformation and grain refinement.

[0039] After the steel plate is rolled, accelerated cooling is initiated at a temperature of 820–840℃, with a cooling rate between 10℃ / s and 20℃ / s. Laminar flow cooling is employed, and the reheat temperature is controlled between 580–620℃. This ensures the steel plate transforms into a mixed microstructure of polygonal ferrite and acicular ferrite, with acicular ferrite comprising 80%–85% and polygonal ferrite 15%–20%. Excessive cooling rate makes it difficult to precisely control the reheat temperature range. If the subsequent stacking temperature is too low, VC in the steel plate will not be able to precipitate and become hydrogen traps, making it difficult to guarantee sufficiently high resistance to hydrogen embrittlement. Insufficient cooling rate will result in hydrogen embrittlement-sensitive microstructures such as pearlite and granular bainite.

[0040] After cooling, the steel plates are stacked in a slow-cooling pit for slow cooling. Temperatures above the selected temperature make it difficult to ensure the integrity of the phase transformation, affecting the final strength-toughness balance and microstructure control of the steel plate. Temperatures below the selected temperature and slow-cooling time prevent the VC from precipitating and becoming hydrogen traps, and also prevent the release of residual stress in the steel, resulting in poor toughness of the steel plate.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] 1) The steel plate produced by the method of the present invention has mechanical properties reaching X100 steel grade, and also has excellent resistance to hydrogen embrittlement, making it suitable for use in hydrogen-contaminated environments.

[0043] 2) The method of the present invention adopts an online quenching and tempering process, which does not require a complicated heat treatment process, resulting in low production cost and high efficiency.

[0044] 3) The low C-Si-Mn and Nb-V-Ti composite microalloying process is adopted to make the microstructure of the steel plate a hydrogen embrittlement resistant structure consisting entirely of acicular ferrite, avoiding the formation of hydrogen embrittlement sensitive structures (granular bainite, pearlite, martensite, etc.). At the same time, a large number of hydrogen traps (NbC, TiC and VC) are dispersed on the matrix, ultimately giving the steel plate a lower hydrogen embrittlement sensitivity. Attached Figure Description

[0045] Figure 1 It is a carbon film extraction replica of X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement. Detailed Implementation

[0046] The present invention will now be described in detail, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0047] An X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement, wherein the chemical composition of the pipeline steel plate by mass percentage is:

[0048] The composition of the pipeline steel plate is as follows: C 0.03%–0.04%, Si 0.10%–0.11%, Mn 0.50%–0.52%, P≤0.004%, S≤0.001%, Al 0.015%–0.02%, Ni 0.20%–0.30%, Cr 0.22%–0.27%, Mo 0.22%–0.30%, Cu 0.21%–0.25%, Nb 0.06%–0.08%, V 0.05%–0.07%, Ti 0.028%–0.040%, with the balance being Fe and unavoidable impurity elements. The microstructure of this pipeline steel plate is entirely acicular ferrite, with NbC, TiC, and VC dispersed in the matrix. (See...) Figure 1 Dispersed nanoscale carbides can be observed.

[0049] The pipeline steel plate has a yield strength ≥690MPa; tensile strength ≥760MPa; impact energy at -20℃ ≥200J; according to standard GBT8650-2015, the hydrogen-induced cracking performance indicators CSR, CLR, and CTR are all 0 in solution A; after being charged with hydrogen for 12 hours in a 0.5mol / L sulfuric acid + 2g / L thiourea solution, a slow strain rate tensile test (SSRT) is performed at a strain rate of 1e. -5 / s, the elongation after fracture of the specimen is greater than 85% under air conditions; a slow strain rate tensile test was conducted under a high-pressure hydrogen environment of 14MPa, with a strain rate of 1e -5 / s, the elongation after fracture of the sample is greater than 80% of that in air.

[0050] A method for manufacturing X100 grade pipeline steel plates with excellent resistance to hydrogen embrittlement:

[0051] 1) Steelmaking and continuous casting: During the steelmaking process, the content of each element is strictly controlled; the smelting process route is: hot metal pretreatment - converter smelting - ladle refining; during the continuous casting process, full-process protective casting is carried out, and one or more of electromagnetic stirring, light pressure or heavy pressure are introduced to strictly control the internal and external quality of the billet. The thickness of the continuously cast billet is 300mm.

[0052] 2) Reheating of billet: The heating temperature is 1150℃~1250℃, and the total time in the furnace is 4~6h.

[0053] 3) High-pressure water descaling: The temperature of the continuous casting billet after descaling is ≥1120℃.

[0054] 4) Rolling billets into steel plates: Two-stage rolling is adopted. In the first stage, during the recrystallization zone rolling, the final rolling temperature is ≥980℃ and the ratio of intermediate billet thickness to finished steel plate thickness is ≥2. In the second stage, during the non-recrystallization zone rolling, the initial rolling temperature is 910~930℃ and the final rolling temperature is ≥840℃.

[0055] 5) Cooling after rolling: After the steel plate is rolled, it is directly quenched online. The cooling start temperature is 820-840℃, the cooling rate is controlled at 25-35℃ / s, and the cooling end temperature is controlled at 200-300℃.

[0056] 6) After the controlled cooling of the steel plate is completed, the steel plate is tempered at a temperature of 580-620℃ and a holding time of 60-90min. The X100 grade pipeline steel plates and manufacturing methods of each embodiment are shown in Tables 1-4. Table 1 is the chemical composition of the embodiment; Table 2 is the rolling parameters of the steel plate of the embodiment; Table 3 is the mechanical properties of the steel plate of the embodiment; and Table 4 is the hydrogen-induced cracking and hydrogen embrittlement related properties of the steel plate of the embodiment.

[0057] Table 1. Chemical composition (wt%) of the steel plate in the example (balance: Fe and unavoidable impurity elements).

[0058] Example C Si Mn P S Al Ni Cr Mo Cu Nb V Ti 1 0.038 0.101 0.51 0.001 0.0006 0.018 0.22 0.24 0.22 0.22 0.064 0.050 0.028 2 0.033 0.108 0.51 0.0012 0.0004 0.018 0.26 0.25 0.29 0.25 0.078 0.055 0.033 3 0.034 0.104 0.50 0.001 0.0005 0.019 0.28 0.25 0.30 0.23 0.074 0.052 0.030 4 0.033 0.106 0.50 0.0013 0.0005 0.017 0.21 0.22 0.24 0.21 0.077 0.052 0.035 5 0.037 0.102 0.51 0.001 0.0006 0.020 0.27 0.22 0.22 0.23 0.066 0.059 0.029 6 0.031 0.103 0.52 0.001 0.0007 0.015 0.29 0.24 0.28 0.22 0.080 0.056 0.030 7 0.036 0.107 0.51 0.0014 0.0005 0.018 0.21 0.23 0.23 0.25 0.069 0.065 0.039 8 0.032 0.108 0.50 0.0012 0.0006 0.016 0.26 0.26 0.27 0.21 0.064 0.054 0.032 9 0.035 0.109 0.51 0.001 0.0005 0.020 0.22 0.27 0.24 0.25 0.071 0.070 0.031 10 0.039 0.106 0.50 0.001 0.0005 0.017 0.29 0.24 0.28 0.25 0.061 0.051 0.033

[0059] Table 2 Rolling process parameters of steel plates in the examples

[0060]

[0061]

[0062] Table 3 Mechanical properties of the steel plates in the examples

[0063]

[0064] Table 4. Hydrogen-induced cracking and hydrogen embrittlement-related properties of the steels in the examples.

[0065]

[0066]

[0067] As can be seen from the data in Tables 1, 2, 3, and 4, the technical solution adopted in this invention produces steel plates with a yield strength ≥690MPa, tensile strength ≥760MPa, and impact energy ≥200J at -20℃. According to standard GBT8650-2015, the hydrogen-induced cracking indices CSR, CLR, and CTR are all 0 in solution A. The elongation after fracture of the electrochemically hydrogen-charged slow-tension specimen is greater than 85% of that in air. The elongation after fracture of the slow-tension specimen in a 10MPa high-pressure hydrogen environment is greater than 80% of that in air. The steel plate possesses excellent strength-toughness matching and resistance to hydrogen embrittlement.

Claims

1. An X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement, characterized in that, The chemical composition of the pipeline steel plate, by mass percentage, is: C 0.03%~0.04%, Si 0.10%~0.11%, Mn 0.50%~0.52%, P≤0.004%, S≤0.001%, Al0.015%~0.02%, Ni 0.20%~0.30%, Cr 0.22%~0.27%, Mo 0.22%~0.30%, Cu 0.21%~0.25%, Nb 0.06%~0.08%, V 0.05%~0.07%, Ti 0.028%~0.040%, with the balance being Fe and unavoidable impurity elements; The microstructure of the steel plate consists entirely of acicular ferrite, with NbC, TiC, and VC dispersed in the matrix. The method for manufacturing the steel plate includes smelting, ladle refining, continuous casting, heating, rolling, cooling, and tempering heat treatment. After the steel plate is rolled, it is directly quenched online. The cooling start temperature is 820-840℃, the cooling rate is controlled at 25-35℃ / s, and the cooling end temperature is controlled at 200-300℃. After the steel plate has cooled, it is subjected to tempering treatment at a temperature of 580–620℃ and a holding time of 60–90 minutes.

2. The X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement according to claim 1, characterized in that, The pipeline steel plate has a yield strength ≥690MPa; tensile strength ≥760MPa; impact energy at -20℃ ≥200J; according to standard GB / T 8650-2015, the hydrogen-induced cracking performance indicators CSR, CLR, and CTR are all 0 in solution A; after being charged with hydrogen for 12 hours in 0.5mol / L sulfuric acid + 2 g / L thiourea solution, a slow strain rate tensile test (SSRT) is performed at a strain rate of 1e. -5 / s, the elongation after fracture of the specimen is greater than 85% of that under air conditions; a slow strain rate tensile test was conducted under a high-pressure hydrogen environment of 14MPa, with a strain rate of 1e -5 / s, the elongation after fracture of the sample is greater than 80% of that in air.

3. A method for manufacturing an X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement according to claim 1 or 2, characterized in that, This includes smelting, ladle refining, continuous casting, heating, rolling, cooling, and tempering heat treatment; After the steel plate is rolled, it is directly quenched online. The cooling start temperature is 820-840℃, the cooling rate is controlled at 25-35℃ / s, and the cooling end temperature is controlled at 200-300℃. After the steel plate has cooled, it is subjected to tempering treatment at a temperature of 580–620℃ and a holding time of 60–90 minutes.

4. The method for manufacturing an X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement according to claim 3, characterized in that, The heating process is as follows: the billet after continuous casting is reheated at a temperature of 1150-1250℃ for a total furnace time of 4-6 hours; high-pressure water descaling is performed, and the temperature of the continuously cast billet after descaling is ≥1120℃.

5. The method for manufacturing an X100 grade pipeline steel plate with excellent resistance to hydrogen embrittlement according to claim 3, characterized in that, The rolling process employs a two-stage rolling process. In the first stage, during the recrystallization zone rolling, the final rolling temperature is ≥980℃ and the ratio of intermediate billet thickness to finished steel plate thickness is ≥2. In the second stage, during the non-recrystallization zone rolling, the initial rolling temperature is 910~930℃ and the final rolling temperature is ≥840℃.

Images