A high-strength steel plate for hydrogen pipeline and its rolling method and application

Abstract

The invention discloses a high-strength steel plate for hydrogen pipeline, a rolling method and an application thereof, and belongs to the technical field of metal materials. The chemical composition of the steel plate is as follows by mass percentage: C: 0.01% to 0.03%, Si: 0.10% to 0.30%, Mn: 0.50% to 1.00%, P: 0.008% to 0.012%, S: 0.0010% to 0.0020%, Cr: 0.20% to 0.40%, Ni: 0.10% to 0.30%, Cu: 0.15% to 0.25%, Nb: 0.030% to 0.050%, Ti: 0.010% to 0.020%, Al: 0.020% to 0.040%, and the balance is Fe and unavoidable impurities. Finer ferrite grains, higher mechanical properties and hydrogen embrittlement resistance are obtained by optimizing the matching of micro-alloy elements with controlled rolling and controlled cooling processes, and cooling and warm rolling after finishing rolling.

Description

Technical Field

[0001] The invention relates to a high-strength steel plate for a hydrogen transmission pipeline and a rolling method and application thereof, belonging to the technical field of metal materials. Background Art

[0002] As a clean energy, hydrogen is gradually replacing oil and natural gas for industrial production. Due to problems such as hydrogen embrittlement, high-strength pipeline steels used for oil and gas transportation, such as X80 and X100, cannot safely transport hydrogen. At present, pipeline steels suitable for transporting hydrogen over longer distances (such as cross-park hydrogen transmission pipelines over 100km) still use ultra-low carbon (C<0.05%) equiaxed ferrite-trace pearlite low-strength grade coils or steel plates with the lowest sensitivity to hydrogen embrittlement, and the risk of hydrogen embrittlement still exists. How to appropriately increase the strength of the steel plate and improve the resistance to hydrogen embrittlement without changing the microstructure type and further reducing the carbon content (C<0.03%) is an urgent problem to be solved for steel plates for hydrogen pipelines.

[0003] Vacancies, dislocations, grain boundaries, phase boundaries, and second phases are all typical hydrogen traps, which can effectively improve the hydrogen embrittlement resistance of steel pipes. Limited by welding performance, low-temperature toughness and cost, ferrite-trace pearlite pipeline steels mostly use refined ferrite grains and add micro-alloying elements such as Nb and V to form dispersed second phases to improve strength and hydrogen embrittlement resistance. This method has almost reached the limit of existing production conditions. Application No. CN202110860390.X discloses a 360MPa grade steel plate for hydrogen-induced crack resistance and a preparation method. By optimizing the alloy content, a wider rolling process window and a -15°C drop hammer average shear area ≥92% of HIC-resistant pipeline steel are obtained, but the optimization mechanism has not been clarified and the chemical composition has not been significantly different. Application No. 202210832091.X obtains 360MPa-grade hydrogen pipeline steel by strictly limiting the content of impurities such as P and S, inclusions, and segregation, and obtaining a grade 9 ferrite grain size. It has very strict requirements on the smelting and continuous casting process, and is close to the control limit of the grain size of medium-thickness steel plates. At the same time, a search of relevant patents found that the maximum tensile strength that can be achieved by ultra-low carbon (C <0.03%) equiaxed ferrite-trace pearlite pipeline steel is about 530MPa (CN202110860390.X). Application No. CN202310542621.1 obtains pipeline steel with high strength but a small amount of acicular ferrite by adding microalloying elements and finely controlling the rolling process. The safety of long-term operation in a hydrogen transmission environment is questionable. Many studies have shown that the acicular ferrite structure used in traditional high-strength pipeline steels such as X80 is directional, which easily leads to localized aggregation of hydrogen atoms and hydrogen embrittlement cracking, and is not suitable for hydrogen pipelines. Although the announcement number CN 113862549 B has produced high-strength and toughness hydrogen embrittlement-resistant hydrogen pipeline steel, the steel plate has undergone tempering treatment after hot rolling, which significantly increases the cost and significantly increases the difficulty of plate shape and surface quality control, making it unsuitable for mass production.

[0004] Therefore, there is an urgent need for a rolling method for equiaxed ferrite-trace pearlite pipeline steel plates to further improve the steel plates' resistance to hydrogen embrittlement while ensuring a higher strength level. Summary of the invention

[0005] The technical problem to be solved by the present invention is to obtain a high-strength steel plate for hydrogen pipeline with excellent hydrogen embrittlement resistance without changing the microstructure type and increasing the cost of alloy elements.

[0006] At the same time, the present invention provides a method for rolling a high-strength steel plate for a hydrogen pipeline.

[0007] At the same time, the present invention provides an application of a high-strength steel plate for hydrogen pipelines in long-distance hydrogen pipelines.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A high-strength steel plate for hydrogen transmission pipeline, whose chemical composition, measured by mass percentage, is as follows: C: 0.01%-0.03%, Si: 0.10%-0.30%, Mn: 0.50%-1.00%, P: 0.008%-0.012%, S: 0.0010%-0.0020%, Cr: 0.20%-0.40%, Ni: 0.10%-0.30%, Cu: 0.15%-0.25%, Nb: 0.030%-0.050%, Ti: 0.010%-0.020%, Al: 0.020%-0.040%, and the balance is Fe and unavoidable impurities.

[0010] The high-strength grade steel plate for hydrogen pipeline has a longitudinal tensile strength of 560-589MPa, a yield strength of 395-436MPa, an average shear area of ​​100% under a -15°C drop hammer, a ferrite grain size ≥9.5, and the HIC test results for hydrogen-induced cracking in three directions are all 0.

[0011] The microstructure type of the high-strength grade hydrogen pipeline steel plate is carbon ferrite-trace pearlite, and the dislocation distribution of the high-strength grade hydrogen pipeline steel plate is uniform.

[0012] A method for rolling a high-strength steel plate for a hydrogen pipeline comprises the following steps:

[0013] S01, the continuous casting billet is heated to 1100℃~1120℃ and kept warm for 3~5h;

[0014] S02, rough rolling is performed immediately after the continuous casting billet is descaled, the final rolling temperature is 970℃~990℃, the total reduction is not less than 80%, the reduction of each of the first two passes is not less than 20%, and the reduction of the last pass is not less than 15%;

[0015] S03, the intermediate billet after rough rolling is heated to 900℃ for finish rolling, the final rolling temperature is 800℃~820℃, the total reduction is not less than 80%, and the final reduction is not less than 10%;

[0016] S04, the steel plate after finish rolling is immediately water-cooled to 250℃~300℃, with a cooling rate of 20~30℃ / s;

[0017] S05, the water-cooled steel plate is subjected to a single-pass warm rolling by a rolling mill with a reduction of 2% to 5% to obtain the finished product thickness;

[0018] S06, the steel plate after warm rolling is immediately water-cooled to below 150°C, with a cooling rate of 10-20°C / s, to obtain a finished steel plate, i.e., a high-strength steel plate for hydrogen pipeline.

[0019] The thickness of the finished steel plate is 10mm-25mm.

[0020] A high-strength steel plate for hydrogen pipeline is used in hydrogen pipelines.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] (1) Based on the composition of traditional ultra-low carbon ferrite-trace pearlite pipeline steel, the carbon content is further reduced to below 0.03%, and micro-alloying elements such as Ti and Nb are added in appropriate amounts. Combined with the controlled rolling and controlled cooling process, the rough rolling temperature and deformation amount are controlled to induce more Ti and Nb carbonitride precipitation while refining the structure, prevent the recovery and recrystallization process of the steel plate during the warm-up process after rough rolling, and retain part of the deformation and fine-grained structure to the finishing stage. Through low-temperature and large-deformation finishing rolling, the austenite grains are further refined, the defect density and ferrite nucleation position are increased, and the final rolling temperature is in the austenite-ferrite two-phase region, which further promotes the recrystallization of ferrite grains. Finally, the room temperature structure is refined to level 9 or above.

[0023] (2) The final rolling temperature is 100°C or higher than the A1 temperature to prevent the untransformed austenite from being rolled into a thin strip, thereby preventing it from transforming into obvious banded pearlite, thus making the structure directional and causing hydrogen accumulation.

[0024] (3) After the final rolling, the steel is rapidly cooled to 250°C to 300°C and then warm rolled with a reduction of 2% to 5% in a single pass, so as to introduce a certain amount of dislocations without significantly changing the microstructure. At the same time, by virtue of the characteristic that the temperature of the core of the rapidly cooled steel plate is higher than that of the surface in a gradient form, the dislocation density of the steel plate is evenly distributed in the thickness direction of the steel plate, avoiding the directionality of dislocation distribution and hydrogen aggregation. In addition, the residual temperature after warm rolling can also eliminate the additional stress caused by warm rolling, and only uniformly distributed dislocations are retained. On the basis of the existing hot rolling strength, the tensile strength of the steel plate is appropriately increased to 560MPa-589MPa, and the number and uniformity of hydrogen traps are significantly increased while improving the strength level of the hot rolled plate, thereby improving the hydrogen embrittlement resistance.

[0025] The present invention realizes the formation of uniformly distributed dislocations, appropriately improves the strength of the steel plate, and improves the hydrogen embrittlement resistance without changing the microstructure type and further reducing the carbon content (C<0.03%) through a specific controlled rolling and controlled cooling process.

[0026] (4) By adding a trace amount of Cu element, a thin and dense oxide layer is formed on the surface of the steel plate to improve corrosion resistance and avoid H + Enters into the steel and causes hydrogen embrittlement.

[0027] The role and proportion of the elements in the present invention are as follows:

[0028] C: Basic strengthening element in steel. It forms a small amount of pearlite in pipeline steel to improve strength. It forms various alloy carbides with microalloying elements to refine grains and disperse strengthen during heating and rolling. The formed alloy carbides can also become hydrogen traps, improve hydrogen capture capacity, and reduce the occurrence of hydrogen embrittlement during use. However, too high C content will reduce plastic toughness and welding performance and generate more pearlite. Pearlite is easy to cause hydrogen aggregation due to the directional nature of the lamellae, so hydrogen pipeline steel requires the C content to be as low as possible. Therefore, the C content of the present invention is 0.01% to 0.03%.

[0029] Si: basic element for strengthening ferrite. As the content of Si increases, the strength of steel parts increases, but the plasticity decreases. The Si content of the present invention is 0.10% to 0.30%.

[0030] Mn: strengthens the matrix in the form of solid solution, slightly refines the room temperature structure, and improves strength and toughness; forms MnS, which reduces the promoting effect of S element on hydrogen embrittlement. The Mn element content of the present invention is 0.50% to 1.00%.

[0031] Cr: A common element in steel that improves strength and hardenability, but it will significantly increase the alloy cost. Too much Cr in pipeline steel will lead to the formation of acicular ferrite structure, resulting in anisotropy and easily causing hydrogen embrittlement. Usually a certain amount of Cr will remain during the steelmaking process. Therefore, the Cr element content of the present invention is 0.20% to 0.40%.

[0032] Ni: An element often added to steel to improve hardenability and toughness. It is expensive and difficult to remove during smelting. It can improve the plastic toughness of steel, especially low-temperature toughness. The Ni content in pipeline steel that does not require very high low-temperature toughness does not need to be very high. Therefore, the Ni content of the present invention is 0.10% to 0.30%.

[0033] Cu: A residual element often found in steel. It can form a dense Cu oxide film on the surface of steel parts to improve corrosion resistance and avoid H + It enters the steel and forms hydrogen embrittlement. However, more than 0.25% Cu easily causes cracks on the surface of the steel plate during hot rolling. Therefore, the Cu content of the present invention is 0.15% to 0.25%.

[0034] Ti, Nb, Al: Microalloying elements commonly used in steel to refine the grain size during hot rolling. They form stable carbonitrides, which hinder the growth of austenite grains during heating of continuous casting billets and during hot rolling, increase the austenite recrystallization temperature, and ultimately refine the room temperature structure and improve strength and toughness. At the same time, they become hydrogen traps to capture hydrogen atoms and avoid hydrogen embrittlement. However, Ti and Nb are relatively expensive, and adding too much will form large-sized carbonitrides. Al is generally introduced during deoxidation and has a lower cost. The three have different precipitation temperatures and different temperatures at which they work, requiring accurate controlled rolling and controlled cooling process matching. Therefore, the present invention has a Nb element content of 0.030% to 0.050%, a Ti element content of 0.010% to 0.020%, and an Al element content of 0.020% to 0.040%.

[0035] P and S are common impurity elements in steel. They reduce the plasticity and toughness of steel materials. The segregated areas are prone to corrosion and hydrogen embrittlement. They should be kept as low as possible in pipeline steel. However, when the P content is less than 0.01% and the S content is less than 0.001%, the smelting difficulty increases significantly, and the cost increases significantly. Excessive Mn can form MnS with S, further reducing the segregated S element. Therefore, the P content of the present invention is 0.008% to 0.012%, and the S content is 0.0010% to 0.0020%.

[0036] Through the present invention, without significantly increasing the cost of alloy elements and the cost of inclusion control, the room temperature microstructure of ultra-low carbon (C < 0.03%) equiaxed ferrite-trace pearlite pipeline steel is refined, and a large number of non-directional hydrogen traps such as grain boundaries, carbonitrides, and uniformly distributed dislocations are introduced. At the same time, a dense copper-containing oxide film is formed on the surface of the steel plate to prevent the entry of exogenous hydrogen. In addition, while refining the grains, the formation of banded pearlite is avoided, and the local aggregation of hydrogen elements is further avoided, thereby improving the hydrogen embrittlement resistance of the steel plate. The longitudinal tensile strength of the steel plate is 560-589MPa, the yield strength is 395-436MPa, the average shear area of ​​the -15℃ drop hammer is 100%, the ferrite grain size is ≥9.5, and the HIC test results of hydrogen crack resistance in three directions are all 0.

[0037] Since the microstructure of the high-strength steel plate for hydrogen pipelines of the present invention is carbon ferrite-trace pearlite, the strength of this microstructure is generally difficult to improve. Under this microstructure, the present invention obtains a steel plate with relatively high strength and resistance to hydrogen embrittlement through a specific element ratio and rolling process, which can be used in long-distance hydrogen pipelines. In addition, the thickness of the finished steel plate of the present invention is 10mm-25mm, and the finished steel plate is a hot-rolled plate. In the hot-rolled plate of this thickness, it is difficult to introduce dislocations in the prior art. However, the present invention controls the deformation amount and the warm rolling temperature of the hot-rolled plate, and the gradient realizes the uniform distribution of dislocations in the thickness direction of the plate, thereby obtaining a steel plate with relatively high strength and resistance to hydrogen embrittlement. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The equilibrium solid solution precipitation law of the main precipitation phase obtained by computer simulation of the raw material composition in Example 1;

[0039] Figure 2 The raw material composition of Example 1 is simulated by computer to obtain the change of austenite content with temperature in the phase diagram and key parameters such as A1 and A3 temperatures are obtained therefrom;

[0040] Figure 3 This is the metallographic structure of the longitudinal section of the finished steel plate of Example 1;

[0041] Figure 4 The uniformly distributed dislocation lines in carbonitride and ferrite (net-shaped and clustered thin black lines in the grains) were taken using a transmission electron microscope in Example 1;

[0042] Figure 5 The uniformly distributed dislocation density in the plate thickness direction photographed by electron backscatter diffraction in Example 1 (the dislocation density increases in order of blue → green → yellow → red);

[0043] Figure 6 The morphologies of carbonitride and ferrite of Comparative Example 4 were photographed using a transmission electron microscope. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings, comparative examples and embodiments. The specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0045] Example 1

[0046] A high-strength steel plate for hydrogen pipeline, the chemical composition of which is shown in Table 1.

[0047] Table 1 Chemical composition (wt%) (the rest is Fe and impurity elements)

[0048] serial number C Si Mn Cr Ni Cu Ti Nb Al P S Comparative Example 1 0.024 0.13 0.78 0.24 0.12 0.05 0.012 0.03 0.02 0.010 0.0015 Comparative Example 2 0.027 0.19 0.84 0.23 0.13 0.22 0.005 0.004 0.01 0.010 0.0013 Example 1 0.025 0.15 0.80 0.25 0.10 0.20 0.015 0.04 0.03 0.010 0.0015 Example 2 0.015 0.28 0.53 0.37 0.30 0.26 0.11 0.03 0.04 0.011 0.0017

[0049] The continuous casting billet is produced according to the ingredients of the above comparative examples and examples. Among them, comparative examples 1, comparative examples 2 and example 1 all adopt the following rolling process: the continuous casting billet is heated to 1150℃ and kept warm for 3.5h, and the continuous casting billet is immediately rough rolled after water descaling, the final rolling temperature is 975℃, the total reduction is 85%, the first two single passes have a reduction of 25%, and the final reduction is 20%. The intermediate billet after rough rolling is heated to 900℃ for finish rolling, the final rolling temperature is 800℃, the total reduction is 85%, and the final reduction is 15%; after cooling to 260℃ at a cooling rate of 25℃ / s, a single pass warm rolling is carried out with a reduction of 4% to obtain the finished product thickness, and it is immediately water-cooled to room temperature at a cooling rate of 15℃ / s. The finished plate thickness is 12mm.

[0050] The steel plates with the components of Example 1, Comparative Example 3 and Comparative Example 4 were respectively manufactured according to the following rolling processes.

[0051] Comparative Example 3: The continuous casting billet is heated to 1150℃ and kept warm for 3.5h. After water descaling, the continuous casting billet is immediately rough rolled, the final rolling temperature is 1050℃, the total reduction is 85%, the first two passes have a single pass reduction of 25%, and the final pass reduction is 20%. After rough rolling, the intermediate billet is heated to 980℃ for finish rolling, the final rolling temperature is 880℃, the total reduction is 85%, and the final pass reduction is 15%; after cooling to 260℃ at a cooling rate of 25℃ / s, a single pass warm rolling is performed with a reduction of 4% to obtain the finished product thickness, and it is immediately water-cooled to room temperature at a cooling rate of 15℃ / s. The finished plate thickness is 12mm.

[0052] Comparative Example 4: The continuous casting slab was heated to 1150℃ and kept warm for 3.5h. After water descaling, the continuous casting slab was immediately rough rolled. The final rolling temperature was 975℃, the total reduction was 85%, the first two passes had a single pass reduction of 25%, and the final pass reduction was 20%. The intermediate slab after rough rolling was heated to 900℃ for finish rolling. The final rolling temperature was 800℃, the total reduction was 85%, and the final pass reduction was 15%; the slab was cooled to room temperature at a cooling rate of 25℃ / s. The finished plate thickness was 12mm.

[0053] According to the composition in Table 1, the continuous casting billet of Example 2 was produced, and the following rolling process was adopted: the continuous casting billet was heated to 1185℃ and kept warm for 4h, and the continuous casting billet was immediately rough rolled after water descaling, the final rolling temperature was 990℃, the total reduction was 85%, the first two single passes had a reduction of 25%, and the final reduction was 20%. The intermediate billet after rough rolling was heated to 900℃ for finish rolling, the final rolling temperature was 820℃, the total reduction was 85%, and the final reduction was 15%; after cooling to 300℃ at a cooling rate of 20℃ / s, a single pass warm rolling was carried out with a reduction of 3% to obtain the finished product thickness, and it was immediately water-cooled to room temperature at a cooling rate of 10℃ / s. The finished plate thickness was 23mm.

[0054] A high-strength steel plate for hydrogen pipeline is used in hydrogen pipelines.

[0055] In order to characterize the performance of the finished steel plate, standard tensile specimens, impact specimens and drop hammer specimens were taken from the steel plate according to the national standard to measure the tensile properties, -20℃ impact energy and -15℃ drop hammer test fracture toughness area ratio (DWTT). Standard specimens were taken to test the HIC performance according to the national standard, and the transverse, longitudinal and normal hydrogen embrittlement cracks were measured respectively.

[0056] GB / T 228.1-2021 Tensile tests on metallic materials Part 1: Room temperature test methods.

[0057] GB / T 229-2020 Charpy pendulum impact test method for metallic materials.

[0058] GB / T 8363-2018 Drop weight tear test method for steel.

[0059] GB T 8650-2015 Evaluation method for resistance of pipeline steel and pressure vessel steel to hydrogen induced cracking.

[0060] GBT 6394-2017 Method for determination of average grain size of metals.

[0061] like Figure 1 As shown, in Example 1, when the continuous casting billet is heated to 1150°C, a large amount of nitrides are still not dissolved, which can hinder the growth of austenite grains. During the hot rolling process, carbonitrides and aluminum nitrides are gradually precipitated. On the basis of refining the grains by rolling with a large deformation amount, the recrystallization process is further hindered, and the austenite grains after rough rolling are refined, which can also prevent the grain growth when the temperature is warmed. When the temperature is raised to 900°C, aluminum nitride and other carbonitrides are precipitated, forming more second phases and hydrogen traps that hinder grain growth. During low-temperature finish rolling, the deformation temperature is low, the deformation amount is large, and the grains are further refined. The final rolling temperature is 800°C, as shown in FIG. Figure 2 As shown in the figure, a large amount of austenite has been transformed into ferrite, and the two-phase rolling further refines the ferrite grains. After the final rolling, there is still a lot of austenite that continues to transform, avoiding the strip distribution of pearlite. The final room temperature structure is as follows Figure 3 As shown, it is an equiaxed ferrite-trace pearlite type, the ferrite grains reach level 9.5, and there is no lamellar pearlite.

[0062] Hot rolling and water cooling followed by warm rolling introduce uniformly distributed dislocations, see Figure 4 and Figure 5 . Figure 4 It can be seen that there are uniform and dense dislocation networks and dislocation clusters in the ferrite grains, which not only achieve appropriate dislocation strengthening but also provide sufficient hydrogen traps. Figure 5 It can be seen that the dislocation distribution inside the ferrite grains and throughout the thickness of the plate is relatively uniform. The final tensile strength of the hot-rolled plate reaches 560MPa-589MPa, and the hydrogen embrittlement resistance is good. The HIC sample is 0 in three directions. The specific mechanical properties are shown in Table 2.

[0063] Comparative Example 1 does not add Cu element, only a residual 0.05%, but other components and hot rolling process are within the scope of the present invention. The conventional mechanical properties and grain size of the finished plate are not much different from those of Example 1, but the HIC test result is 5%, and hydrogen embrittlement problem occurs.

[0064] Comparative Example 2 does not add microalloying elements such as Ti, Nb, and Al, but other components and hot rolling processes are within the scope of the present invention. The grain size of the finished plate is significantly smaller, and the grain size is significantly larger, resulting in a significant decrease in tensile strength, yield strength, elongation, impact energy, and DWTT compared to Example 1. The HIC test result is 10%, and hydrogen embrittlement occurs.

[0065] The rough rolling start temperature, finish rolling start rolling and final rolling temperature of Comparative Example 3 are significantly higher than the range of the present invention, resulting in high deformation temperature and coarse austenite grains. In addition, the role of micro-alloy elements cannot be fully exerted, which ultimately leads to significantly larger finished product grains, which are level 8.0, insufficient plasticity and toughness, a small number of grain boundaries, and a large size of carbonitrides. The HIC test result is 5%, and hydrogen embrittlement occurs.

[0066] Comparative Example 4 The heating, rough rolling, and finishing rolling processes are the same as those of Example 1, but the steel plate is directly water-cooled to room temperature after finishing rolling without warm rolling, resulting in a significantly lower strength, although the grain size and plastic toughness of the steel plate are similar to those of Example 1. However, since uniformly distributed dislocations are not introduced, the number of hydrogen traps is significantly reduced, such as Figure 6 As shown, there are almost no dislocations in the ferrite, and the hydrogen traps are obviously insufficient, resulting in a HIC test result of 10%, and hydrogen embrittlement problem.

[0067] The composition and rolling process of the steel plate of Example 2 are within the scope of the present invention, only the specific chemical composition, heating and rolling temperatures are slightly changed, and the thickness of the finished steel plate is different. The mechanical properties, grain size and HIC test results of the obtained steel plate product are close to those of Example 1, meeting the performance requirements of high-strength hydrogen embrittlement resistant pipeline steel.

[0068] Table 2 Mechanical properties, grain size and hydrogen embrittlement resistance (HIC)

[0069]

[0070] Example 3

[0071] A high-strength steel plate for hydrogen pipeline, whose chemical composition, measured by mass percentage, is as follows: C: 0.01%, Si: 0.10%, Mn: 0.50%, P: 0.008%, S: 0.0010%, Cr: 0.20%, Ni: 0.20%, Cu: 0.15%, Nb: 0.040%, Ti: 0.010%, Al: 0.020%, and the balance is Fe and unavoidable impurities.

[0072] The high-strength grade steel plate for hydrogen pipeline has a longitudinal tensile strength of 568MPa, a yield strength of 425MPa, an average shear area of ​​100% under a -15°C drop hammer, a ferrite grain size of 10.0, and HIC test results for hydrogen-induced cracking in three directions are all 0.

[0073] The microstructure type of the high-strength grade hydrogen pipeline steel plate is carbon ferrite-trace pearlite, and the dislocation distribution of the high-strength grade hydrogen pipeline steel plate is uniform.

[0074] A method for rolling a high-strength steel plate for a hydrogen pipeline comprises the following steps:

[0075] S01, continuous casting billet is heated to 1100℃ and kept for 3h;

[0076] S02, rough rolling immediately after continuous casting billet descaling, final rolling temperature 970℃, total reduction 80%, single reduction of the first two passes 20%, and final reduction 15%;

[0077] S03, the intermediate billet after rough rolling is heated to 900℃ for finish rolling, the final rolling temperature is 810℃, the total reduction is 80%, and the final reduction is 10%;

[0078] S04, the steel plate after finish rolling is immediately water-cooled to 250°C, with a cooling rate of 30°C / s;

[0079] S05, the water-cooled steel plate is subjected to a single-pass warm rolling by a rolling mill with a reduction of 2% to obtain a finished product thickness;

[0080] S06, the steel plate after warm rolling is immediately water-cooled to 150°C at a cooling rate of 20°C / s to obtain a finished steel plate, i.e., a high-strength steel plate for hydrogen pipeline.

[0081] The thickness of the finished steel plate is 25mm.

[0082] A high-strength steel plate for hydrogen pipeline is used in long-distance hydrogen pipelines.

[0083] Long distance is greater than 400km.

[0084] Example 4

[0085] A high-strength steel plate for hydrogen pipeline, whose chemical composition, measured by mass percentage, is as follows: C: 0.03%, Si: 0.30%, Mn: 1.00%, P: 0.012%, S: 0.0020%, Cr: 0.40%, Ni: 0.15%, Cu: 0.25%, Nb: 0.040%, Ti: 0.020%, Al: 0.030%, and the balance is Fe and unavoidable impurities.

[0086] The high-strength grade steel plate for hydrogen pipeline has a longitudinal tensile strength of 577MPa, a yield strength of 428MPa, an average shear area of ​​100% under a -15°C drop hammer, a ferrite grain size of 10.5, and HIC test results for hydrogen-induced cracking in three directions are all 0.

[0087] The microstructure type of the high-strength grade hydrogen pipeline steel plate is carbon ferrite-trace pearlite, and the dislocation distribution of the high-strength grade hydrogen pipeline steel plate is uniform.

[0088] A method for rolling a high-strength steel plate for a hydrogen pipeline comprises the following steps:

[0089] S01, continuous casting billet is heated to 1120℃ and kept for 5h;

[0090] S02, rough rolling immediately after continuous casting billet descaling, final rolling temperature 990℃, total reduction 90%, single reduction 30% in the first two passes, and 20% in the last pass;

[0091] S03, the intermediate billet after rough rolling is heated to 900℃ for finish rolling, the final rolling temperature is 820℃, the total reduction is 90%, and the final reduction is 20%;

[0092] S04, the steel plate after finish rolling is immediately water-cooled to 280°C, with a cooling rate of 28°C / s;

[0093] S05, the water-cooled steel plate is subjected to a single-pass warm rolling by a rolling mill with a reduction of 5% to obtain the finished product thickness;

[0094] S06, the steel plate after warm rolling is immediately water-cooled to 100°C at a cooling rate of 12°C / s to obtain a finished steel plate, i.e., a high-strength steel plate for hydrogen pipeline.

[0095] The thickness of the finished steel plate is 10mm.

[0096] A high-strength steel plate for hydrogen pipeline is used in long-distance hydrogen pipelines.

[0097] The longest distance is 400-800km. Currently, according to actual project needs, the longest hydrogen pipeline that has been built is 217km, and the longest hydrogen pipeline to be built is 400km.

[0098] It should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting the intention that the claimed invention requires more features than those expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all of the features of the previously disclosed embodiments. Therefore, the claims that follow the detailed description are hereby expressly incorporated into the detailed description, with each claim itself serving as a separate embodiment of the present invention.

[0099] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is selected primarily for readability and teaching purposes, rather than for explaining or defining the subject matter of the present invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is illustrative, not restrictive, with respect to the scope of the present invention, which is defined by the appended claims.

[0100] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for rolling a high-strength steel plate for a hydrogen pipeline, characterized in that: The chemical composition is as follows in mass percentage: C: 0.01%~0.03%, Si: 0.10%~0.30%, Mn: 0.50%~1.00%, P: 0.008%~0.012%, S: 0.0010%~0.0020%, Cr: 0.20%~0.40%, Ni: 0.10~0.30%, Cu: 0.15%~0.25%, Nb: 0.030%~0.050%, Ti: 0.010%~0.020%, Al: 0.020%~0.040%, the balance is Fe and unavoidable impurities; The rolling method comprises the following steps: S01, continuous casting billet is heated to 1100℃~1120℃ and kept warm for 3~5h; S02, rough rolling is performed immediately after the continuous casting billet is descaled, the final rolling temperature is 970℃~990℃, the total reduction is not less than 80%, the reduction of each of the first two passes is not less than 20%, and the reduction of the last pass is not less than 15%; S03, the intermediate billet after rough rolling is heated to 900℃ for finish rolling, the final rolling temperature is 800℃~820℃, the total reduction is not less than 80%, and the final reduction is not less than 10%; S04, the steel plate after finish rolling is immediately water-cooled to 250℃~300℃, with a cooling rate of 20~30℃ / s; S05, the water-cooled steel plate is subjected to a single-pass warm rolling by a rolling mill with a reduction of 2% to 5% to obtain the finished product thickness; S06, the steel plate after warm rolling is immediately water-cooled to below 150°C, with a cooling rate of 10-20°C / s, to obtain a finished steel plate, i.e., a high-strength steel plate for hydrogen pipeline.

2. The method for rolling a high-strength steel plate for hydrogen pipeline according to claim 1, characterized in that: The high-strength grade steel plate for hydrogen pipeline has a longitudinal tensile strength of 560-589MPa, a yield strength of 395-436MPa, an average shear area of ​​100% under a -15°C drop hammer, a ferrite grain size ≥9.5, and the HIC test results for hydrogen-induced cracking in three directions are all 0.

3. The method for rolling a high-strength steel plate for hydrogen pipeline according to claim 1, characterized in that: The microstructure type of the high-strength grade hydrogen pipeline steel plate is carbon ferrite-trace pearlite, and the dislocation distribution of the high-strength grade hydrogen pipeline steel plate is uniform.

4. The rolling method according to claim 1, characterized in that: The thickness of the finished steel plate is 10mm-25mm.

5. Application of a high-strength steel plate for hydrogen pipeline obtained by the rolling method according to any one of claims 1 to 4 in hydrogen pipelines.

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