A high-strength 11MnNiMoDR ​​medium-thick plate for cryogenic containers and its manufacturing method

Abstract

This invention discloses a high-strength 11MnNiMoDR ​​medium-thick plate for cryogenic containers and its production method, belonging to the field of steel production technology. The chemical composition of the medium-thick plate by mass percentage is as follows: C: 0.03%~0.11%, Mn: 1.4%~1.9%, P≤0.008%, S≤0.003%, Si: 0.1%~0.40%, Ni: 0.3%~0.9%, Mo: 0.1%~0.30%, Nb≤0.05%, V≤0.05%, Al≥0.02%, [H]≤2ppm, [N]≤120ppm, [O]≤30ppm, with the balance being Fe and unavoidable impurities. The sum of the above components is 100%. This method, through reasonable composition design and matching with appropriate smelting, rolling, and post-rolling rapid cooling and tempering heat treatment processes, produces medium-thick plates with higher toughness and strength, covering the full thickness specifications required for the construction of storage and transportation facilities.

Description

Technical Field

[0001] This invention relates to a medium-thick plate and its production method, specifically to a high-strength 11MnNiMoDR ​​medium-thick plate for cryogenic containers and its production method, belonging to the field of steel production technology. Background Technology

[0002] With the increasing demand for cryogenic petrochemical raw materials and auxiliary materials such as propylene, propane, ethane, and acetylene in my country, the demand for ultra-low temperature steel used in the construction of cryogenic spherical tanks or storage tanks has also increased. To ensure the safety of steel plates, steel plates with temperatures lower than -88℃ for liquid ethane and other media are required; to reduce equipment weight and material costs, steel plates need higher strength; and for more precise design and manufacturing of certain parts of storage and transportation facilities, thinner steel plates are also needed, such as 5mm steel plates required for cryogenic containers. However, the production of thin steel plates is difficult due to the rapid cooling during the rolling process, which easily leads to defects such as waviness, warping, and rolling defects.

[0003] A search of invention patent application number 202010235608.8 reveals a method for producing ultra-low temperature high-strength 13MnNi6-3 container steel. This method employs billet casting combined with a reasonable controlled rolling and cooling process, normalizing + tempering, to produce 13MnNi6-3 container steel with a diameter of 30-60mm, a yield strength ≥375MPa, a tensile strength ≥510MPa, and a low-temperature impact testing temperature of -90℃; application number 202010235602.0 The invention patent describes a method for producing thick 13MnNi6-3 container steel with ultra-low temperature high core impact. This method uses billet production combined with a reasonable controlled rolling process, and a quenching + tempering process to produce 80mm thick 13MnNi6-3 container steel with an ultra-low temperature of -80℃. The tensile strength of its 1 / 4 thickness and 1 / 2 thickness is ≥498MPa. The invention patent with application number 202211513903.0 describes a high-strength and high-toughness 11MnNiDR steel plate for pressure vessels and its manufacturing method. This method uses low carbon equivalent design and the addition of Ni, Nb, and Ti alloys, controlled rolling and controlled cooling, and quenching + tempering to produce 11MnNiDR steel with a yield strength ≥400MPa, tensile strength ≥560MPa, and a low-temperature impact testing temperature of -70℃. The microstructure is low-carbon bainite + ferrite, and the reported maximum thickness is 100mm.

[0004] The above patents all involve designing the composition and matching the appropriate process to produce low-temperature steel products. However, the product strength is relatively low and the impact temperature cannot meet the requirements of lower temperatures than liquid cryogenic media such as ethane. Furthermore, the thinnest specification reported is not even 5mm steel plate, which is difficult to produce. How to effectively improve the toughness and strength of steel plates and cover the full thickness specifications required for the construction of storage and transportation facilities through redesigning the composition and production process is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems and overcome the shortcomings of existing technologies, this invention provides a high-strength 11MnNiMoDR ​​medium-thick plate for cryogenic containers and its production method. This method, through reasonable composition design and matching with appropriate smelting, rolling, and post-rolling rapid cooling and tempering heat treatment processes, produces medium-thick plates with higher toughness and strength, covering the full thickness specifications required for the construction of storage and transportation facilities.

[0006] To solve the above technical problems, the present invention provides a high-strength 11MnNiMoDR ​​medium-thick plate for cryogenic containers. The chemical composition of the medium-thick plate by mass percentage is as follows: C: 0.03%~0.11%, Mn: 1.4%~1.9%, P≤0.008%, S≤0.003%, Si: 0.1%~0.40%, Ni: 0.3%~0.9%, Mo: 0.1%~0.30%, Nb≤0.05%, V≤0.05%, Al≥0.02%, [H]≤2ppm, [N]≤120ppm, [O]≤30ppm, with the balance being Fe and unavoidable impurities. The sum of the above components is 100%.

[0007] The technical solution further defined in this invention is:

[0008] Furthermore, in the aforementioned 11MnNiMoDR ​​medium-thick plate for high-strength cryogenic containers, the chemical composition of the medium-thick plate by mass percentage is as follows: C: 0.03%~0.10%, Mn: 1.4%~1.8%, P≤0.005%, S≤0.002%, Si: 0.1%~0.40%, Ni: 0.3%~0.7%, Mo: 0.15%~0.25%, Nb: 0.02%~0.04%, V: 0.020%~0.040%, Al: 0.02%~0.07%, [H]≤2ppm, [N]≤60ppm, [O]≤20ppm, with the balance being Fe and unavoidable impurities, and the sum of the above components is 100%.

[0009] This invention also designs a method for producing 11MnNiMoDR ​​medium-thick plates for high-strength cryogenic containers, specifically including the following steps:

[0010] (1) KR pre-desulfurization treatment: After the first slag removal, when the temperature is controlled at 1350-1370℃, the purified magnesium desulfurizing agent is sprayed for 25 minutes. Desulfurization is carried out by stirring. After desulfurization, the S in the molten iron is ≤0.006%, and the desulfurization temperature drop is ≤50℃. After the desulfurization, the slag is removed a second time.

[0011] (2) Steelmaking: Scrap steel, molten iron and slag are added to the oxygen top and bottom blowing converter. During the blowing process, the lance position is controlled according to the temperature of the molten iron. The final slag basicity is controlled at 4.0 and the final P content is ≤0.005%.

[0012] Argon blowing is carried out throughout the LF furnace refining process. The temperature rise and slag formation are completed within 10-15 minutes after the start of refining. The calcium wire feeding rate is controlled according to the sulfur content in the molten steel, the calcium-aluminum ratio of the top slag and the calcium content. Soft blowing continues for 5-10 minutes after wire feeding ends. The molten steel temperature is controlled at 1640-1680℃ at the end of refining, with the final sulfur content ≤ 0.001%.

[0013] The molten steel enters the RH vacuum treatment for 25-40 minutes. At the end of the RH vacuum smelting, the temperature of the molten steel is 1560-1590℃, and the final H is ≤2ppm.

[0014] (3) Continuous casting: Enter the continuous casting station. Argon blowing protection is used for continuous casting throughout the process. The casting temperature is 1521~1546℃, the tundish superheat is 20-45℃, the billet pulling speed is 0.70~1.15m / min, and the steel surface is kept from turning red during the tundish casting process.

[0015] The thickness of the cast slab is 150mm and 460mm;

[0016] (4) Rolling: The total time the slab is in the furnace is ≥8 min / cm, the temperature is 1140~1250℃, and then it is rolled after exiting the furnace;

[0017] <10mm steel plate is rolled in ordinary rolling, continuously rolled to the set thickness;

[0018] Two-stage controlled rolling of steel plates with a thickness ≥10mm: The first stage uses a large rolling pass reduction rate for continuous and uninterrupted rolling to ensure that the deformed metal undergoes dynamic and static recrystallization;

[0019] The second stage adopts non-recrystallization controlled rolling, with a rolling pass reduction rate of ≥10%;

[0020] The temperature for controlled cooling after rolling is 720-740℃.

[0021] (5) Heat treatment: After the steel plate is cooled and shot blasted, it is quenched and tempered. After quenching, it is water-cooled to room temperature, and after tempering, it is air-cooled to room temperature.

[0022] The technical solution further defined in this invention is:

[0023] Furthermore, in the aforementioned production method of 11MnNiMoDR ​​medium-thick plates for high-strength cryogenic containers, the basicity of the LF furnace top slag in step (2) is controlled at 5-7, and the slag quantity is controlled at 12-16 kg / ton of steel.

[0024] In the aforementioned production method of 11MnNiMoDR ​​medium-thick plate for high-strength cryogenic containers, in step (4), the rolling temperature of the steel plate with a thickness of <10mm is controlled to be ≥1200℃, the final rolling temperature is ≥830℃, and the number of rolling passes is ≥11.

[0025] In the aforementioned production method of 11MnNiMoDR ​​medium-thick plate for high-strength ultra-low temperature containers, in step (4), the steel plate with a thickness ≥10mm is rolled in two stages, the total number of rolling passes in the recrystallization zone is 4, the cumulative reduction rate in the recrystallization zone is ≥40%, the final rolling temperature is 820℃-860℃, the post-rolling reddening temperature is 730-760℃, the cooling rate is controlled at 20-30℃ / s, and the microstructure of the rolled steel plate is refined.

[0026] In the aforementioned production method of 11MnNiMoDR ​​medium-thick plate for high-strength ultra-low temperature containers, the quenching temperature in step (5) is 870-910℃, the total furnace time is 2.0±1min / mm×steel plate thickness / mm, and it is water-cooled to room temperature; the tempering temperature is 590-620℃, the total heating time is 3.25±1min / mm×steel plate thickness / mm, and it is air-cooled to room temperature.

[0027] In the aforementioned production method of 11MnNiMoDR ​​medium-thick plates for high-strength cryogenic containers, the thickness of the produced steel plates is 5mm-80mm.

[0028] In the aforementioned production method of 11MnNiMoDR ​​medium-thick plates for high-strength cryogenic containers, the produced steel plates have a microstructure of tempered sorbite + ferrite, a grain size of grade 8.0, a yield strength ≥440MPa, a tensile strength ≥570MPa, an elongation after fracture ≥20%, and an average impact energy at -100℃ ≥120J.

[0029] The beneficial effects of this invention are:

[0030] (1) Phosphorus and sulfur increase the brittleness of steel, phosphorus reduces the plasticity of steel, phosphorus causes unstable welding performance, and sulfur reduces the ductility and toughness of steel, causing cracks during rolling. The content of phosphorus and sulfur must be strictly controlled. Carbon plays a key role in the strength of steel, but it will reduce its plasticity and toughness. To ensure the toughness at ultra-low temperatures, a low content needs to be controlled. Nickel can lower and raise the ductile-brittle transition temperature of steel, improve toughness, and also improve strength, but it is expensive and needs to be added in an appropriate amount. Molybdenum can improve hardenability and hot strength, and improve tempering stability. Manganese can improve hardenability and significantly improve strength, but when the content is too high, the plasticity and low-temperature toughness of steel will decrease. An appropriate amount needs to be added. Nb and V can refine the grains, reduce temper brittleness, and improve welding performance. V can significantly improve the strength of steel. Through pre-desulfurization treatment and steelmaking, S≤0.002% is controlled. Through deep dephosphorization in the converter, P≤0.005% is controlled. This invention is designed with lower C, Si, P and S are strictly controlled, with harmful elements P and S controlled at C: 0.03%–0.11% and Si: 0.1%–0.40%. Appropriate Ni, Mo, and Mn alloying elements are added, with their contents controlled as follows: Ni: 0.3%–0.9%, Mo: 0.1%–0.30%, and Mn: 1.4%–1.9%. Appropriate amounts of trace elements Nb ≤ 0.05% and V ≤ 0.05% are added, along with appropriate smelting, rolling, and rapid post-rolling cooling. However, by refining the steel plate grains and using a suitable quenching and tempering heat treatment process, 5-80mm steel plates with a microstructure of tempered sorbite + ferrite, a grain size of grade 8.0, a yield strength ≥440MPa, a tensile strength ≥570MPa, an elongation after fracture ≥20%, and an average impact energy of -100℃ ≥120J are produced. This successfully solves the technical challenge of matching high strength with high toughness requirements in steel plates at ultra-low temperatures, and can meet the construction requirements of storage and transportation containers for low-temperature petrochemical raw materials such as ethane.

[0031] (2) This invention successfully solved the technical difficulties of producing high-strength, -100℃ high-impact toughness ultra-low temperature 5mm thick 11MnNiMoDR ​​container steel on a 3500mm rolling mill production line. Attached Figure Description

[0032] Figure 1 The image shows the metallographic structure of the 11MnNiMoDR ​​medium-thick plate used in the high-strength cryogenic container in Example 1.

[0033] Figure 2 The image shows the metallographic structure of the 11MnNiMoDR ​​medium-thick plate used in the high-strength cryogenic container in Example 2.

[0034] Figure 3 These are metallographic images of the 11MnNiMoDR ​​medium-thick plate used in the high-strength cryogenic container in Example 3;

[0035] Figure 4This is a grain size photograph of the 11MnNiMoDR ​​medium-thick plate used in the high-strength cryogenic container in Example 2. Detailed Implementation

[0036] To make the present invention clearer, the following description, in conjunction with the accompanying drawings, further illustrates a thick-walled alloy steel and its production method. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Example 1

[0037] This embodiment provides a 5mm thick 11MnNiMoDR ​​medium-thick plate for high-strength cryogenic containers. The chemical composition (unit, wt%) of the medium-thick plate is as follows: C: 0.038%, Mn: 1.63%, P: 0.005%, S: 0.001%, Si: 0.14%, Ni: 0.38%, Mo: 0.18%, Nb: 0.03%, V: 0.028%, Al: 0.028%, [H]: 1ppm, [N]: 30ppm, [O]: 18ppm, with the balance being Fe and unavoidable impurities. The sum of the above components is 100%.

[0038] The production method of the above-mentioned high-strength cryogenic container 11MnNiMoDR ​​medium-thick plate specifically includes the following steps:

[0039] (1) KR pre-desulfurization treatment: After the first slag removal, when the temperature is controlled at 1370℃, purified magnesium desulfurizing agent is sprayed for 25 minutes. Desulfurization is carried out by stirring. The S in the molten iron after desulfurization is 0.006%, and the temperature drop of desulfurization is 43℃. After the desulfurization, the slag is removed a second time.

[0040] (2) Steelmaking: Scrap steel, molten iron and slag are added to a 150-ton oxygen top and bottom blowing converter for smelting. During the blowing process, the lance position is controlled according to the temperature of the molten iron. The final slag basicity is controlled at 4.0 and the final P content is 0.005%.

[0041] LF furnace refining, with argon blowing throughout. Temperature rise and slag formation are completed within 15 minutes of refining. The top slag basicity is controlled at 5, and the slag quantity is controlled at 14 kg / ton of steel. The calcium wire feed rate is controlled at 140 m / furnace based on the sulfur content in the molten steel, the calcium-aluminum ratio of the refining slag and the Ca content in the top slag. Soft blowing is performed for 10 minutes after wire feeding ends. The molten steel temperature is controlled at 1660℃ at the end of refining, and the final sulfur content is 0.0008%.

[0042] The molten steel was subjected to RH vacuum treatment for 35 minutes. At the end of the RH vacuum smelting, the temperature of the molten steel was 1580℃ and the final H was 1ppm.

[0043] (3) Continuous casting: Enter the continuous casting station. Argon blowing protection is used for continuous casting throughout the process. The casting temperature is 1538℃, the tundish superheat is 37℃, the billet pulling speed is 1.15m / min, and the steel surface is kept from turning red during the tundish casting process.

[0044] During the steel casting process, the amount of argon blown by the stopper rod is controlled, the liquid level in the crystallizer fluctuates slightly, and the thickness of the cast slab is 150mm.

[0045] (4) Rolling: The total time the slab is in the furnace is 155 min, the temperature is 1245℃, and it is rolled after exiting the furnace;

[0046] The final rolling temperature is 835℃, the rolling passes are 15, and it is continuously rolled to 5.5mm;

[0047] (5) Heat treatment: After the steel plate is cooled and shot blasted, it is quenched and tempered. The temperature is 908℃ and the time in the furnace is 15min. It is then water-cooled to room temperature and taken out of the furnace. After tempering at 610℃ and the time in the furnace is 20min, it is taken out of the furnace and air-cooled to room temperature.

[0048] The high-strength, cryogenic container 11MnNiMoDR ​​medium-thick plate produced in this embodiment has a microstructure of tempered sorbite plus ferrite, such as... Figure 1 As shown, according to existing technology, the grain size is grade 8.0, the yield strength is 609 MPa, the tensile strength is 662 MPa, the elongation after fracture is 27%, and the average impact energy at -100℃ is 201 J. Example 2

[0049] This embodiment provides a 36mm thick 11MnNiMoDR ​​medium-thick plate for high-strength cryogenic containers. The chemical composition (unit, wt%) of the medium-thick plate is as follows: C: 0.038%, Mn: 1.63%, P: 0.005%, S: 0.001%, Si: 0.14%, Ni: 0.38%, Mo: 0.18%, Nb: 0.03%, V: 0.028%, Al: 0.028%, [H]: 1ppm, [N]: 30ppm, [O]: 18ppm, with the balance being Fe and unavoidable impurities. The sum of the above components is 100%.

[0050] The production method of the above-mentioned high-strength cryogenic container 11MnNiMoDR ​​medium-thick plate specifically includes the following steps:

[0051] (1) KR pre-desulfurization treatment: After the first slag removal, when the temperature is controlled at 1370℃, purified magnesium desulfurizing agent is sprayed for 25 minutes. Desulfurization is carried out by stirring. After desulfurization, the S in the molten iron is 0.006%, and the temperature drop of desulfurization is 43℃. After the desulfurization is completed, the slag is removed a second time.

[0052] (2) Steelmaking: Scrap steel, molten iron and slag are added to a 150-ton oxygen top and bottom blowing converter. During the blowing process, the lance position is controlled according to the temperature of the molten iron. The final slag basicity is controlled at 4.0 and the final P content is 0.005%.

[0053] Argon blowing is used throughout the refining process in the LF furnace. The temperature rise and slag formation are completed within 15 minutes of the start of refining. The basicity of the top slag is controlled at 5, and the slag quantity is controlled at 14 kg / ton of steel. The calcium wire feed rate is controlled at 140 m / furnace based on the sulfur content in the molten steel, the calcium-aluminum ratio of the refining slag and the calcium content in the top slag. Soft blowing is carried out for 10 minutes after the wire feeding ends. The temperature of the molten steel is controlled at 1660℃ at the end of refining, and the final sulfur content is 0.0008%.

[0054] The molten steel was subjected to RH vacuum treatment for 35 minutes. At the end of the RH vacuum smelting, the temperature of the molten steel was 1580℃ and the final H was 1ppm.

[0055] (3) Continuous casting: Enter the continuous casting station. Argon blowing protection is used for continuous casting throughout the process. The casting temperature is 1538℃, the tundish superheat is 37℃, the billet pulling speed is 1.15m / min, and the steel surface is kept from turning red during the tundish casting process.

[0056] During the steel casting process, the amount of argon blown by the stopper rod is controlled, the liquid level in the crystallizer fluctuates slightly, and the thickness of the cast slab is 150mm.

[0057] (4) Rolling: The total time the slab is in the furnace is 150 min, the temperature is 1150℃, and it is rolled after exiting the furnace;

[0058] The cumulative reduction rate in the recrystallization zone of the first stage is 50%. The second stage adopts non-recrystallization controlled rolling with a reduction rate of ≥10% per rolling pass, a final rolling temperature of 830℃, a post-rolling reddening temperature of 740℃, and a rolling thickness of 36.8mm.

[0059] (5) Heat treatment: After the steel plate is cooled and shot blasted, it is quenched and tempered. The temperature is 880℃ and the furnace time is 108min. It is then water-cooled to room temperature and taken out of the furnace. After tempering at 600℃ and the furnace time is 117min, it is taken out of the furnace and air-cooled to room temperature.

[0060] The 36mm thick 11MnNiMoDR ​​medium-thick plate for high-strength cryogenic containers produced in this embodiment has a microstructure of tempered sorbite and ferrite, as shown in the figure. Figure 2 and 4 As shown; according to existing technology, the grain size is grade 8.0, the yield strength is 581MPa, the tensile strength is 647MPa, the elongation after fracture is 26%, and the average impact energy at -100℃ is 212J. Example 3

[0061] This embodiment provides a 11MnNiMoDR ​​medium-thick plate for high-strength cryogenic containers with a thickness of 80mm. The chemical composition (unit, wt%) of the medium-thick plate is as follows: C: 0.07%, Mn: 1.58%, P: 0.003%, S: 0.0009%, Si: 0.19%, Ni: 0.72%, Mo: 0.21%, Nb: 0.03%, V: 0.034%, Al: 0.031%, [H]: 1ppm, [N]: 40ppm, [O]: 15ppm, with the balance being Fe and unavoidable impurities. The sum of the above components is 100%.

[0062] The above-mentioned production method of 11MnNiMoDR ​​medium-thick plate for high-strength cryogenic containers is characterized by the following steps:

[0063] (1) KR pre-desulfurization treatment: After the first slag removal, when the temperature is controlled at 1360℃, the purified magnesium desulfurizing agent is sprayed for 25 minutes. Desulfurization is carried out by stirring. The S in the molten iron after desulfurization is 0.005%, and the desulfurization temperature drops to 38℃. After the desulfurization, the slag is removed a second time.

[0064] (2) Steelmaking: Scrap steel, molten iron and slag are added to a 150-ton oxygen top and bottom blowing converter. During the blowing process, the lance position is controlled according to the temperature of the molten iron. The final slag basicity is controlled at 4.0 and the final P content is 0.004%.

[0065] Argon blowing is used throughout the refining process in the LF furnace. The temperature rise and slag formation are completed within 10 minutes of the start of refining. The basicity of the top slag is controlled at 6, and the slag quantity is controlled at 15 kg / ton of steel. The calcium wire feed rate is controlled at 130 m / furnace based on the sulfur content in the molten steel, the calcium-aluminum ratio of the top slag and the calcium content of the refining slag. Soft blowing is carried out for 5 minutes after the wire feeding ends. The temperature of the molten steel is controlled at 1670℃ at the end of refining, and the final sulfur content is 0.0007%.

[0066] The molten steel was subjected to RH vacuum treatment for 35 minutes. At the end of the RH vacuum smelting, the temperature of the molten steel was 1580℃ and the final H was 0.8ppm.

[0067] (3) Continuous casting: Enter the continuous casting station. Argon blowing protection is used for continuous casting throughout the process. The casting temperature is 1542℃, the tundish superheat is 41℃, the billet pulling speed is 0.8m / min, and the steel surface is kept from turning red during the tundish casting process.

[0068] During the steel casting process, the amount of argon blown by the stopper rod was controlled, the liquid level in the crystallizer fluctuated slightly, and the thickness of the cast slab was 460mm.

[0069] (4) Rolling: The total time the slab is in the furnace is 300 min, the temperature is 1148℃, and it is rolled after exiting the furnace;

[0070] The cumulative reduction rate in the recrystallization zone of the first stage is 45%. The second stage adopts non-recrystallization controlled rolling with a reduction rate of ≥10% per rolling pass, a final rolling temperature of 851℃, a post-rolling reddening temperature of 738℃, and a rolling thickness of 80.9mm.

[0071] (5) Heat treatment: After the steel plate is cooled and shot blasted, it is quenched and tempered. The temperature is 875℃ and the furnace time is 152min. It is then water-cooled to room temperature and taken out of the furnace. After tempering at 595℃ and the furnace time is 181min, it is taken out of the furnace and air-cooled to room temperature.

[0072] This embodiment describes the production method of 11MnNiMoDR ​​medium-thick plates for high-strength cryogenic containers with a thickness of 80mm. The microstructure consists of tempered sorbite and ferrite. Figure 3 As shown; according to existing technology, the grain size is grade 8.0, the yield strength is 479MPa, the tensile strength is 595MPa, the elongation after fracture is 25%, and the average impact energy at -100℃ is 189J.

[0073] This invention produces steel plates with a microstructure of tempered sorbite + ferrite that meets requirements by strictly controlling harmful elements P and S, using low C, adding appropriate Ni, Mo and Mn alloying elements, controlling appropriate Nb and V trace element content, and combining appropriate smelting, rolling and post-rolling rapid cooling and tempering heat treatment processes.

[0074] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A method for producing 11MnNiMoDR ​​medium-thick plates for high-strength cryogenic containers, characterized in that, The chemical composition of this medium-thick plate, by mass percentage, is as follows: C: 0.038%, Mn: 1.63%, P: 0.005%, S: 0.001%, Si: 0.14%, Ni: 0.38%, Mo: 0.18%, Nb: 0.03%, V: 0.028%, Al: 0.028%, [H]: 1ppm, [N]: 30ppm, [O]: 18ppm, with the balance being Fe and unavoidable impurities. The sum of all the above components is 100%. The production method of the above-mentioned high-strength cryogenic container 11MnNiMoDR ​​medium-thick plate specifically includes the following steps: (1) KR pre-desulfurization treatment: After the first slag removal, when the temperature is controlled at 1370℃, purified magnesium desulfurizing agent is sprayed for 25 minutes. Desulfurization is carried out by stirring. The S in the molten iron after desulfurization is 0.006%, and the temperature drop of desulfurization is 43℃. After the desulfurization, the slag is removed a second time. (2) Steelmaking: Scrap steel, molten iron and slag are added to a 150-ton oxygen top and bottom blowing converter for smelting. During the blowing process, the lance position is controlled according to the temperature of the molten iron. The final slag basicity is controlled at 4.0 and the final P content is 0.005%. LF furnace refining, with argon blowing throughout. Temperature rise and slag formation are completed within 15 minutes of refining. The top slag basicity is controlled at 5, and the slag quantity is controlled at 14 kg / ton of steel. The calcium wire feed rate is controlled at 140 m / furnace based on the sulfur content in the molten steel, the calcium-aluminum ratio of the refining slag and the Ca content in the top slag. Soft blowing is performed for 10 minutes after wire feeding ends. The molten steel temperature is controlled at 1660℃ at the end of refining, and the final sulfur content is 0.0008%. The molten steel was subjected to RH vacuum treatment for 35 minutes. At the end of RH vacuum smelting, the temperature of the molten steel was 1580℃ and the final H was 1ppm. (3) Continuous casting: Enter the continuous casting station. Argon blowing protection is used for continuous casting throughout the process. The casting temperature is 1538℃, the tundish superheat is 37℃, the billet pulling speed is 1.15m / min, and the steel surface is kept from turning red during the tundish casting process. During the steel casting process, the amount of argon blown by the stopper rod is controlled, the liquid level in the crystallizer fluctuates slightly, and the thickness of the cast slab is 150mm. (4) Rolling: The total time the slab is in the furnace is 155 min, the temperature is 1245℃, and it is rolled after exiting the furnace; The final rolling temperature is 835℃, the rolling passes are 15, and it is continuously rolled to 5.5mm; (5) Heat treatment: After the steel plate is cooled and shot blasted, it is quenched and tempered. The temperature is 908℃ and the time in the furnace is 15min. It is then water-cooled to room temperature and taken out of the furnace. After tempering at 610℃ and the time in the furnace is 20min, it is taken out of the furnace and air-cooled to room temperature. The 5mm thick high-strength cryogenic container 11MnNiMoDR ​​medium-thick plate produced has a microstructure of tempered sorbite plus ferrite, a grain size of 8.0, a yield strength of 609MPa, a tensile strength of 662MPa, an elongation after fracture of 27%, and an average impact energy of 201J at -100℃.

2. A method for producing 11MnNiMoDR ​​medium-thick plates for high-strength cryogenic containers, characterized in that, The chemical composition of this medium-thick plate, by mass percentage, is as follows: C: 0.038%, Mn: 1.63%, P: 0.005%, S: 0.001%, Si: 0.14%, Ni: 0.38%, Mo: 0.18%, Nb: 0.03%, V: 0.028%, Al: 0.028%, [H]: 1ppm, [N]: 30ppm, [O]: 18ppm, with the balance being Fe and unavoidable impurities. The sum of all the above components is 100%. The production method of the above-mentioned high-strength cryogenic container 11MnNiMoDR ​​medium-thick plate specifically includes the following steps: (1) KR pre-desulfurization treatment: After the first slag removal, when the temperature is controlled at 1370℃, purified magnesium desulfurizing agent is sprayed for 25 minutes. Desulfurization is carried out by stirring. After desulfurization, the S in the molten iron is 0.006%, and the temperature drop of desulfurization is 43℃. After the desulfurization is completed, the slag is removed a second time. (2) Steelmaking: Scrap steel, molten iron and slag are added to a 150-ton oxygen top and bottom blowing converter. During the blowing process, the lance position is controlled according to the temperature of the molten iron. The final slag basicity is controlled at 4.0 and the final P content is 0.005%. Argon blowing is used throughout the refining process in the LF furnace. The temperature rise and slag formation are completed within 15 minutes of the start of refining. The basicity of the top slag is controlled at 5, and the slag quantity is controlled at 14 kg / ton of steel. The calcium wire feed rate is controlled at 140 m / furnace based on the sulfur content in the molten steel, the calcium-aluminum ratio of the refining slag and the calcium content in the top slag. Soft blowing is carried out for 10 minutes after the wire feeding ends. The temperature of the molten steel is controlled at 1660℃ at the end of refining, and the final sulfur content is 0.0008%. The molten steel was subjected to RH vacuum treatment for 35 minutes. At the end of RH vacuum smelting, the temperature of the molten steel was 1580℃ and the final H was 1ppm. (3) Continuous casting: Enter the continuous casting station. Argon blowing protection is used for continuous casting throughout the process. The casting temperature is 1538℃, the tundish superheat is 37℃, the billet pulling speed is 1.15m / min, and the steel surface is kept from turning red during the tundish casting process. During the steel casting process, the amount of argon blown by the stopper rod is controlled, the liquid level in the crystallizer fluctuates slightly, and the thickness of the cast slab is 150mm. (4) Rolling: The total time the slab is in the furnace is 150 min, the temperature is 1150℃, and it is rolled after exiting the furnace; The cumulative reduction rate in the recrystallization zone of the first stage is 50%. The second stage adopts non-recrystallization controlled rolling with a reduction rate of ≥10% per rolling pass, a final rolling temperature of 830℃, a post-rolling reddening temperature of 740℃, and a rolling thickness of 36.8mm. (5) Heat treatment: After the steel plate is cooled and shot blasted, it is quenched and tempered. The temperature is 880℃ and the furnace time is 108min. It is then water-cooled to room temperature and taken out of the furnace. After tempering at 600℃ and the furnace time is 117min, it is taken out of the furnace and air-cooled to room temperature. The 36mm thick high-strength cryogenic container 11MnNiMoDR ​​medium-thick plate produced has a microstructure of tempered sorbite plus ferrite, a grain size of 8.0, a yield strength of 581MPa, a tensile strength of 647MPa, an elongation after fracture of 26%, and an average impact energy of 212J at -100℃.

3. A method for producing 11MnNiMoDR ​​medium-thick plates for high-strength cryogenic containers, characterized in that, The chemical composition of this medium-thick plate, by mass percentage, is as follows: C: 0.07%, Mn: 1.58%, P: 0.003%, S: 0.0009%, Si: 0.19%, Ni: 0.72%, Mo: 0.21%, Nb: 0.03%, V: 0.034%, Al: 0.031%, [H]: 1ppm, [N]: 40ppm, [O]: 15ppm, with the balance being Fe and unavoidable impurities. The sum of all the above components is 100%. The production method of the above-mentioned high-strength cryogenic container 11MnNiMoDR ​​medium-thick plate specifically includes the following steps: (1) KR pre-desulfurization treatment: After the first slag removal, when the temperature is controlled at 1360℃, the purified magnesium desulfurizing agent is sprayed for 25 minutes. Desulfurization is carried out by stirring. The S in the molten iron after desulfurization is 0.005%, and the desulfurization temperature drops to 38℃. After the desulfurization, the slag is removed a second time. (2) Steelmaking: Scrap steel, molten iron and slag are added to a 150-ton oxygen top and bottom blowing converter. During the blowing process, the lance position is controlled according to the temperature of the molten iron. The final slag basicity is controlled at 4.0 and the final P content is 0.004%. Argon blowing is used throughout the refining process in the LF furnace. The temperature rise and slag formation are completed within 10 minutes of the start of refining. The basicity of the top slag is controlled at 6, and the slag quantity is controlled at 15 kg / ton of steel. The calcium wire feed rate is controlled at 130 m / furnace based on the sulfur content in the molten steel, the calcium-aluminum ratio of the top slag and the calcium content of the refining slag. Soft blowing is carried out for 5 minutes after the wire feeding ends. The temperature of the molten steel is controlled at 1670℃ at the end of refining, and the final sulfur content is 0.0007%. The molten steel was subjected to RH vacuum treatment for 35 minutes. At the end of the RH vacuum smelting, the temperature of the molten steel was 1580℃ and the final H was 0.8ppm. (3) Continuous casting: Enter the continuous casting station. Argon blowing protection is used for continuous casting throughout the process. The casting temperature is 1542℃, the tundish superheat is 41℃, the billet pulling speed is 0.8m / min, and the steel surface is kept from turning red during the tundish casting process. During the steel casting process, the amount of argon blown by the stopper rod was controlled, the liquid level in the crystallizer fluctuated slightly, and the thickness of the cast slab was 460mm. (4) Rolling: The total time the slab is in the furnace is 300 min, the temperature is 1148℃, and it is rolled after exiting the furnace; The cumulative reduction rate in the recrystallization zone of the first stage is 45%. The second stage adopts non-recrystallization controlled rolling with a reduction rate of ≥10% per rolling pass, a final rolling temperature of 851℃, a post-rolling reddening temperature of 738℃, and a rolling thickness of 80.9mm. (5) Heat treatment: After the steel plate is cooled and shot blasted, it is quenched and tempered. The temperature is 875℃ and the furnace time is 152min. It is then water-cooled to room temperature and taken out of the furnace. After tempering at 595℃ and the furnace time is 181min, it is taken out of the furnace and air-cooled to room temperature. The production method of 11MnNiMoDR ​​medium-thick plate for high-strength cryogenic containers with a thickness of 80mm is described. The microstructure is tempered sorbite plus ferrite with a grain size of 8.

0. The yield strength is 479MPa, the tensile strength is 595MPa, the elongation after fracture is 25%, and the average impact energy at -100℃ is 189J.

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