11MnNiMoDR medium-thickness plate for high-strength ultralow-temperature container and production method of 11MnNiMoDR medium-thickness plate

Abstract

The invention discloses a 11MnNiMoDR medium plate for a high-strength ultralow-temperature container and a production method of the 11MnNiMoDR medium plate, and belongs to the technical field of steel production, the medium plate comprises the following chemical components in percentage by mass: 0.03-0.11% of C, 1.4-1.9% of Mn, less than or equal to 0.008% of P, less than or equal to 0.003% of S, 0.1-0.40% of Si, 0.3-0.9% of Ni, 0.1-0.30% of Mo, less than or equal to 0.05% of Nb, less than or equal to 0.05% of V, more than or equal to 0.02% of Al, less than or equal to 2ppm of H, less than or equal to 120ppm of N, less than or equal to 30ppm of 0 and the balance of Fe and inevitable impurities, and the sum of the components is 100 According to the method, through reasonable component design, proper smelting, rolling, rapid cooling after rolling and quenching and tempering heat treatment processes are matched, and the produced medium-thickness plate is higher in toughness and strength and covers the full-thickness specification required by construction of storage and transportation facilities.

Description

Technical Field

[0001] The invention relates to a medium and thick plate and a production method thereof, in particular to a 11MnNiMoDR ​​medium and thick plate for a high-strength ultra-low temperature container and a production method thereof, and belongs to the technical field of steel production. Background Art

[0002] With the increasing demand for low-temperature petrochemical raw materials such as propylene, propane, ethane and acetylene in my country, the demand for ultra-low temperature steel used in the construction of storage and transportation equipment such as cryogenic spherical tanks or storage tanks has increased. In order to ensure the safety of steel plates, steel plates with a lower temperature than the medium temperature of -88℃ liquid ethane are required; in order to reduce the weight of equipment and material costs, steel plates need to have higher strength; in order to design and manufacture more precisely some locations of storage and transportation facilities, thinner steel plates are also required, such as 5mm steel plates required for cryogenic containers. However, due to the rapid cooling of the rolling process, thin steel plates are prone to defects such as waves, curvature, and rolling scrap, making it difficult to produce successfully.

[0003] The invention patent with application number 202010235608.8 introduced a method for producing ultra-low temperature high-strength 13MnNi6-3 container steel. The method adopts ingot production and combines reasonable controlled rolling and controlled cooling, normalizing + tempering process. The produced 13MnNi6-3 container steel has a specification of 30-60mm, a yield strength of ≥375MPa, a tensile strength of ≥510MPa, and a low-temperature impact test temperature of -90℃; application number 202010235602.0 The invention patent introduces a method for producing ultra-low temperature, high core impact and large thickness 13MnNi6-3 container steel. The method adopts ingot production and cooperates with a reasonable controlled rolling process, and the quenching + tempering process produces 80mm thick -80℃ ultra-high 13MnNi6-3 container steel, and its 1 / 4 thickness and 1 / 2 thickness tensile strength are ≥498MPa; the invention patent with application number 202211513903.0 introduces a high-strength and high-toughness 11MnNiDR steel plate for pressure vessels and its manufacturing method. The method uses low-carbon equivalent design and the addition of Ni, Nb, and Ti alloys, controlled rolling and controlled cooling, quenching + tempering to produce 11MnNiDR steel with a yield strength of ≥400MPa, tensile strength ≥560MPa, and a low-temperature impact detection temperature of -70℃. The microstructure type is low-carbon bainite + ferrite, and the reported maximum thickness is 100mm.

[0004] The above patents all produce low-temperature steel products by designing components and matching appropriate processes. However, the product strength is relatively low and the impact temperature cannot meet the requirements lower than that of liquid low-temperature media such as ethane. In addition, the thinnest specification reported does not reach the 5mm steel plate that is difficult to produce. How to effectively improve the toughness and strength of the steel plate and cover the full thickness specifications required for the construction of storage and transportation facilities by redesigning the components and production processes is a technical problem that urgently needs to be solved. Summary of the invention

[0005] In view of the above technical problems, the present invention overcomes the shortcomings of the prior art and provides a high-strength 11MnNiMoDR ​​medium and thick plate for ultra-low temperature containers and a production method thereof. The method produces medium and thick plates with higher toughness and strength and covering the full thickness specifications required for the construction of storage and transportation facilities through reasonable component design, matching appropriate smelting, rolling and post-rolling rapid cooling and tempering heat treatment processes.

[0006] In order to solve the above technical problems, the present invention provides a 11MnNiMoDR ​​medium and thick plate for a high-strength ultra-low temperature container, wherein the chemical composition of the medium and thick plate is as follows by mass percentage: C: 0.03% to 0.11%, Mn: 1.4% to 1.9%, P≤0.008%, S≤0.003%, Si: 0.1% to 0.40%, Ni: 0.3% to 0.9%, Mo: 0.1% to 0.30%, Nb≤0.05%, V≤0.05%, Al≥0.02%, [H]≤2ppm, [N]≤120ppm, [0]≤30ppm, and the remainder is Fe and unavoidable impurities, and the sum of the above components is 100%.

[0007] The technical solution further defined in the present invention is: Furthermore, in the aforementioned 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers, the chemical composition of the medium and thick plates is as follows in percentage by mass: C: 0.03% to 0.10%, Mn: 1.4% to 1.8%, P≤0.005%, S≤0.002%, Si: 0.1% to 0.40%, Ni: 0.3% to 0.7%, Mo: 0.15% to 0.25%, Nb: 0.02% to 0.04%, V: 0.020% to 0.040%, Al: 0.02% to 0.07%, [H]≤2ppm, [N]≤60ppm, [0]≤20ppm, the remainder is Fe and unavoidable impurities, and the sum of the above components is 100%.

[0008] The present invention also provides a method for producing a 11MnNiMoDR ​​medium and thick plate for a high-strength ultra-low temperature container, which specifically comprises the following steps: (1) KR pre-desulfurization treatment: After the first slag removal, the temperature is controlled at 1350-1370°C, and purified magnesium desulfurizer 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°C. After the deslag removal, the second slag removal is completed; (2) Molten steel smelting: Scrap steel, molten iron and slag are added to the oxygen top and bottom combined blowing converter. During the blowing process, the gun position is controlled according to the molten iron temperature, the final slag basicity is controlled to 4.0, and the final P content is ≤0.005%; Argon is blown during the whole refining process of LF furnace. The temperature rise and slag formation are completed within 10-15 minutes after the start of refining. The calcium wire feeding amount is controlled according to the S content in the molten steel, the calcium-aluminum ratio of the top slag of the refining slag and the Ca content. Soft blowing is performed for 5-10 minutes after the wire feeding. At the end of refining, the molten steel temperature is controlled to be 1640-1680℃, and the end point S≤0.001%; The molten steel enters the RH vacuum treatment for 25-40 minutes. At the end of the RH vacuum smelting, the molten steel temperature is 1560-1590℃, and the end point H≤2ppm; (3) Continuous casting: Enter the continuous casting station, and use argon blowing to protect the casting throughout the continuous casting process. The casting temperature is 1521-1546°C, the tundish superheat is 20-45°C, the billet drawing rate is 0.70-1.15m / min, and the steel liquid level does not turn red during the tundish pouring process; The thickness of the cast slab is 150mm and 460mm; (4) Rolling: The total time of the slab in the furnace is ≥8 min / cm, the temperature is 1140-1250°C, and it is rolled out of the furnace; <10mm steel plate is rolled in general and continuously rolled to the set thickness; Two-stage controlled rolling of steel plates with a thickness of ≥10mm: In the first stage, continuous and uninterrupted rolling is performed with a large rolling pass reduction rate to ensure dynamic and static recrystallization of the deformed metal; The second stage adopts non-recrystallization controlled rolling, and the rolling reduction rate is ≥10%; The return temperature of controlled cooling after rolling is 720-740℃; (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.

[0009] The technical solution further defined in the present invention is: Furthermore, in the aforementioned method for producing 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers, the basicity of the LF furnace top slag in step (2) is controlled at 5-7, and the slag amount is controlled at 12-16 kg / ton of steel.

[0010] In the above-mentioned method for producing 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers, in step (4), the furnace temperature of the steel plate with a thickness of less than 10 mm is controlled to be ≥1200°C, the final rolling temperature is ≥830°C, and the number of rolling passes is ≥11.

[0011] In the production method of the 11MnNiMoDR ​​medium and thick plate for high-strength ultra-low temperature containers, in step (4), the steel plate with a thickness of ≥10 mm is subjected to two-stage controlled rolling, the total rolling passes in the recrystallization zone are 4 times, the cumulative reduction rate in the recrystallization zone is ≥40%, the final rolling temperature is 820°C-860°C, the red-returning temperature after rolling is 730-760°C, the cooling rate is controlled to 20-30°C / s, and the microstructure of the rolled steel plate is refined.

[0012] In the above-mentioned production method of 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers, the quenching temperature in step (5) is 870-910°C, the total time in the furnace is 2.0±1min / mm×steel plate thickness / mm, and water cooling is performed to room temperature; the tempering temperature is 590-620°C, the total heating time is 3.25±1min / mm×steel plate thickness / mm, and air cooling is performed to room temperature.

[0013] In the above-mentioned method for producing 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers, the thickness of the produced steel plates is 5mm-80mm.

[0014] In the production method of the above-mentioned 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers, the produced steel plate structure is tempered troostite + ferrite, the grain size is grade 8.0, the yield strength is ≥440MPa, the tensile strength is ≥570MPa, the elongation after fracture is ≥20%, and the average impact energy at -100℃ is ≥120J.

[0015] The beneficial effects of the present invention are: (1) Phosphorus and sulfur increase the brittleness of steel, phosphorus reduces the plasticity of steel, phosphorus causes unstable welding performance, sulfur reduces the ductility and toughness of steel, and causes cracks during rolling, so the content of phosphorus and sulfur needs to be strictly controlled; carbon plays a key role in the strength of steel, but it will reduce its plasticity and toughness. To ensure ultra-low temperature toughness, it is necessary to control the content to a lower level; nickel can reduce the toughness-brittle transition temperature of steel, improve toughness, and at the same time improve strength, but it is expensive and needs to be added in an appropriate amount; molybdenum can improve hardenability and heat resistance, 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 decrease, so it needs to be added in an appropriate amount; Nb and V can refine grains, reduce tempering brittleness, and improve welding performance. V can significantly improve the strength of steel; through pre-desulfurization treatment and molten steel smelting, S is controlled to be ≤0.002%; through deep dephosphorization in the converter, P is controlled to be ≤0.005%; the present invention is designed to lower C, Si, P, S, strictly control harmful elements P, S, control C: 0.03% ~ 0.11%, Si: 0.1% ~ 0.40%, add appropriate Ni, Mo and Mn alloy elements, control their contents respectively Ni: 0.3% ~ 0.9%, Mo: 0.1% ~ 0.30%, Mn: 1.4% ~ 1.9%, add appropriate content of Nb ≤ 0.05%, V ≤ 0.05% trace elements, with appropriate smelting, rolling and rapid cooling after rolling but, refine the steel plate grains; through appropriate quenching and tempering heat treatment process, produce 5-80mm steel plates with the structure of tempered bainite + ferrite, grain size of 8.0, yield strength ≥440MPa, tensile strength ≥570MPa, elongation after fracture ≥20%, and average impact energy of -100℃ ≥120J. It successfully solves the technical difficulties of matching high strength of steel plates under ultra-low temperature and high toughness requirements, and can meet the construction needs of low-temperature petrochemical raw material storage and transportation containers such as ethane.

[0016] (2) The present invention successfully solves 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a metallographic structure photograph of the 11MnNiMoDR ​​medium and thick plate for high-strength ultra-low temperature container in Example 1; Figure 2 This is a metallographic structure photograph of the 11MnNiMoDR ​​medium and thick plate for high-strength ultra-low temperature container in Example 2; Figure 3 This is a metallographic structure photograph of 11MnNiMoDR ​​medium and thick plate for high-strength ultra-low temperature container in Example 3; Figure 4 This is a grain size photograph of 11MnNiMoDR ​​medium and thick plate for high-strength ultra-low temperature container in Example 2. DETAILED DESCRIPTION

[0018] To make the present invention more clear, a thick-walled alloy steel and a production method thereof of the present invention are further described below in conjunction with the accompanying drawings. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example 1

[0019] The present embodiment provides a 11MnNiMoDR ​​medium and thick plate for a high-strength ultra-low temperature container with a thickness of 5 mm. The chemical composition (unit, wt%) of the medium and thick plate is as follows by mass percentage: 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, [0]: 18ppm, and the balance is Fe and unavoidable impurities. The sum of the above components is 100%.

[0020] The production method of the above-mentioned 11MnNiMoDR ​​medium and thick plate for high-strength ultra-low temperature container specifically comprises the following steps: (1) KR pre-desulfurization treatment: After the first slag removal, the temperature was controlled at 1370°C, and purified magnesium desulfurizer was sprayed for 25 minutes. Desulfurization was carried out by stirring. The sulfur content in the molten iron after desulfurization was 0.006%, and the temperature drop of desulfurization was 43°C. After the deslag removal, the second slag removal was completed; (2) Molten steel smelting: Scrap steel, molten iron and slag are added to a 150-ton oxygen top and bottom double-blown converter for smelting. During the blowing process, the gun position is controlled according to the molten iron temperature, the final slag basicity is controlled to 4.0, and the final P content is 0.005%; LF furnace refining, argon blowing throughout the whole process, heating and slag formation are completed within 15 minutes after the start of refining, the top slag basicity is controlled at 5, the slag amount is controlled at 14kg / ton steel, the calcium wire feeding amount is controlled at 140m / furnace according to the S content in molten steel, the calcium-aluminum ratio of the top slag of the refining slag and the Ca content, the soft blowing is 10min after the wire feeding, the molten steel temperature is controlled at 1660℃ at the end of refining, and the end point S is 0.0008%; The molten steel enters the RH vacuum treatment for 35 minutes. At the end of the RH vacuum smelting, the molten steel temperature is 1580°C and the end point H is 1ppm. (3) Continuous casting: Enter the continuous casting station, and use argon blowing to protect the casting throughout the continuous casting process. The casting temperature is 1538°C, the tundish superheat is 37°C, the billet drawing rate is 1.15m / min, and the steel liquid level is kept from turning red during the tundish pouring process; During the steel pouring 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 poured slab is 150mm; (4) Rolling: The total furnace time of the slab is 155 min, the temperature is 1245°C, and then the slab is rolled out of the furnace; The final rolling temperature is 835℃, the rolling pass is 15, and the continuous rolling is to 5.5mm; (5) Heat treatment: After the steel plate is cooled and shot blasted, it is quenched and tempered. The quenching temperature is 908℃ and the furnace time is 15min. The steel plate is water cooled to room temperature and then taken out of the furnace. The tempering temperature is 610℃ and the furnace time is 20min. The steel plate is then air cooled to room temperature.

[0021] The high-strength 11MnNiMoDR ​​medium and thick plate for ultra-low temperature containers produced in this embodiment has a microstructure of tempered troostite plus ferrite. Figure 1 As shown, after inspection by existing technology, the grain size is 8.0, the yield strength is 609MPa, the tensile strength is 662MPa, the elongation after fracture is 27%, and the average impact energy at -100℃ is 201J. Example 2

[0022] The present embodiment provides a 11MnNiMoDR ​​medium and thick plate with a thickness of 36 mm for a high-strength ultra-low temperature container. The chemical composition (unit, wt%) of the medium and thick plate is as follows by mass percentage: 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]: 1 ppm, [N]: 30 ppm, [0]: 18 ppm, and the remainder is Fe and unavoidable impurities. The sum of the above components is 100%.

[0023] The production method of the above-mentioned 11MnNiMoDR ​​medium and thick plate for high-strength ultra-low temperature container specifically comprises the following steps: (1) KR pre-desulfurization treatment: After the first slag removal, the temperature was controlled at 1370°C, and purified magnesium desulfurizer was sprayed for 25 minutes. Desulfurization was carried out by stirring. The sulfur content in the molten iron after desulfurization was 0.006%, and the temperature drop of desulfurization was 43°C. After the deslag removal, the second slag removal was completed; (2) Molten steel smelting: Scrap steel, molten iron and slag are added to a 150-ton oxygen top and bottom double-blown converter. During the blowing process, the gun position is controlled according to the molten iron temperature, the final slag basicity is controlled to 4.0, and the final P content is 0.005%; Argon was blown during the whole refining process of LF furnace. The temperature was raised and slag was formed within 15 minutes after the start of refining. The basicity of top slag was controlled at 5, and the slag amount was controlled at 14kg / ton steel. The calcium wire feeding amount was controlled at 140m / furnace according to the S content in molten steel, the calcium-aluminum ratio of the top slag of the refining slag, and the Ca content. Soft blowing lasted for 10 minutes after the wire feeding. At the end of refining, the molten steel temperature was controlled at 1660℃, and the end point S was 0.0008%; The molten steel enters the RH vacuum treatment for 35 minutes. At the end of the RH vacuum smelting, the molten steel temperature is 1580°C and the end point H is 1ppm. (3) Continuous casting: Enter the continuous casting station, and use argon blowing to protect the casting throughout the continuous casting process. The casting temperature is 1538°C, the tundish superheat is 37°C, the billet drawing rate is 1.15m / min, and the steel liquid level is kept from turning red during the tundish pouring process; During the steel pouring 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 poured slab is 150mm; (4) Rolling: The total furnace time of the slab is 150 min, the temperature is 1150°C, and the slab is rolled out of the furnace; The cumulative reduction rate in the recrystallization zone in the first stage is 50%, and the non-recrystallization controlled rolling is adopted in the second stage. The rolling pass reduction rate is ≥10%, the final rolling temperature is 830℃, the red-returning temperature after rolling is 740℃, and the rolling thickness is 36.8mm; (5) Heat treatment: After the steel plate is cooled and shot blasted, it is quenched and tempered at 880°C for 108 min in the furnace and then water-cooled to room temperature before being taken out of the furnace; tempered at 600°C for 117 min in the furnace and then air-cooled to room temperature before being taken out of the furnace.

[0024] The 36 mm high-strength 11MnNiMoDR ​​medium and thick plate for ultra-low temperature containers produced in this embodiment has a microstructure of tempered troostite plus ferrite. Figure 2 and 4 As shown; after inspection by existing technology, the grain size is 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

[0025] The present embodiment provides a 80mm thick high-strength 11MnNiMoDR ​​medium and thick plate for ultra-low temperature containers, and the chemical composition (unit, wt%) of the medium and thick plate is as follows by mass percentage: 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, [0]: 15ppm, and the remainder is Fe and unavoidable impurities, and the sum of the above components is 100%.

[0026] The production method of the 11MnNiMoDR ​​medium and thick plate for the high-strength ultra-low temperature container is characterized in that it specifically comprises the following steps: (1) KR pre-desulfurization treatment: After the first slag removal, the temperature is controlled at 1360°C, and purified magnesium desulfurizer is sprayed for 25 minutes. Desulfurization is carried out by stirring. After desulfurization, the sulfur content in the molten iron is 0.005%, and the desulfurization temperature drops to 38°C. After the deslag removal, the second slag removal is completed; (2) Molten steel smelting: Scrap steel, molten iron and slag are added to a 150-ton oxygen top and bottom double-blown converter. During the blowing process, the gun position is controlled according to the molten iron temperature, the final slag basicity is controlled to 4.0, and the final P content is 0.004%; Argon was blown during the whole refining process of LF furnace. The temperature was raised and slag was formed within 10 minutes after the start of refining. The basicity of top slag was controlled at 6, and the slag amount was controlled at 15kg / ton steel. The calcium wire feeding amount was controlled at 130m / furnace according to the S content in molten steel, the calcium-aluminum ratio of the top slag of the refining slag, and the Ca content. Soft blowing lasted for 5 minutes after the wire feeding. At the end of refining, the molten steel temperature was controlled at 1670℃, and the end point S was 0.0007%; The molten steel enters the RH vacuum treatment for 35 minutes. At the end of the RH vacuum smelting, the molten steel temperature is 1580°C and the end point H is 0.8ppm. (3) Continuous casting: Enter the continuous casting station, and use argon blowing to protect the casting throughout the continuous casting process. The casting temperature is 1542°C, the tundish superheat is 41°C, the billet drawing rate is 0.8m / min, and the steel liquid level is kept from turning red during the tundish pouring process; During the steel pouring 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 furnace time of the slab is 300 min, the temperature is 1148 °C, and then the slab is rolled out of the furnace; The cumulative reduction rate in the recrystallization zone in the first stage is 45%, and the second stage adopts non-recrystallization controlled rolling, with a rolling pass reduction rate of ≥10%, a final rolling temperature of 851°C, a red-returning temperature after rolling of 738°C, 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 quenching temperature is 875℃ and the furnace time is 152min. The steel plate is water cooled to room temperature and then taken out of the furnace. The tempering temperature is 595℃ and the furnace time is 181min. The steel plate is then air cooled to room temperature.

[0027] The production method of the 11MnNiMoDR ​​medium and thick plate for high-strength ultra-low temperature containers produced in this embodiment has a microstructure of tempered troostite plus ferrite, such as Figure 3 As shown; after inspection by existing technology, the grain size is 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.

[0028] The present invention strictly controls harmful elements P and S, adopts low C, adds appropriate Ni, Mo and Mn alloy elements, controls the appropriate content of Nb and V trace elements in the composition design, and cooperates with appropriate smelting, rolling and post-rolling rapid cooling and tempering heat treatment processes to produce a steel plate with a microstructure type of tempered troost + ferrite that meets the requirements.

[0029] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A high-strength 11MnNiMoDR ​​medium and thick plate for ultra-low temperature containers, characterized in that: The chemical composition of the medium and thick plate is as follows in percentage by mass: 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, [0]≤30ppm, the remainder is Fe and unavoidable impurities, and the sum of the above components is 100%.

2. The 11MnNiMoDR ​​medium and thick plate for high-strength ultra-low temperature containers according to claim 1, characterized in that: The chemical composition of the medium and thick plate is as follows in percentage by mass: 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, [0]≤20ppm, the remainder is Fe and unavoidable impurities, and the sum of the above components is 100%.

3. A method for producing the 11MnNiMoDR ​​medium and thick plate for high-strength ultra-low temperature containers as claimed in claim 1 or 2, characterized in that: The specific steps include: (1) KR pre-desulfurization treatment: After the first slag removal, the temperature is controlled at 1350-1370°C, and purified magnesium desulfurizer 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°C. After the deslag removal, the second slag removal is completed; (2) Molten steel smelting: Scrap steel, molten iron and slag are added to the oxygen top and bottom combined blowing converter. During the blowing process, the gun position is controlled according to the molten iron temperature, the final slag basicity is controlled to 4.0, and the final P content is ≤0.005%; Argon is blown during the whole refining process of LF furnace. The temperature rise and slag formation are completed within 10-15 minutes after the start of refining. The calcium wire feeding amount is controlled according to the S content in the molten steel, the calcium-aluminum ratio of the top slag of the refining slag and the Ca content. Soft blowing is performed for 5-10 minutes after the wire feeding. At the end of refining, the molten steel temperature is controlled to be 1640-1680℃, and the end point S≤0.001%; The molten steel enters the RH vacuum treatment for 25-40 minutes. At the end of the RH vacuum smelting, the molten steel temperature is 1560-1590℃, and the end point H≤2ppm; (3) Continuous casting: Enter the continuous casting station, and use argon blowing to protect the casting throughout the continuous casting process. The casting temperature is 1521-1546°C, the tundish superheat is 20-45°C, the billet drawing rate is 0.70-1.15m / min, and the steel liquid level does not turn red during the tundish pouring process; The thickness of the cast slab is 150mm and 460mm; (4) Rolling: The total time of the slab in the furnace is ≥8 min / cm, the temperature is 1140-1250°C, and it is rolled out of the furnace; <10mm steel plate is rolled in general and continuously rolled to the set thickness; Two-stage controlled rolling of steel plates with a thickness of ≥10mm: In the first stage, continuous and uninterrupted rolling is performed with a large rolling pass reduction rate to ensure dynamic and static recrystallization of the deformed metal; The second stage adopts non-recrystallization controlled rolling, and the rolling reduction rate is ≥10%; The return temperature of controlled cooling after rolling is 720-740℃; (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.

4. The method for producing 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers according to claim 3, characterized in that: In the step (2), the basicity of the LF top slag is controlled at 5-7, and the slag amount is controlled at 12-16 kg / ton of steel.

5. The method for producing 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers according to claim 3, characterized in that: In the step (4), the steel plate with a thickness of less than 10 mm is rolled to control the furnace temperature of the slab to be ≥1200°C, the final rolling temperature to be ≥830°C, and the number of rolling passes to be ≥11.

6. The method for producing 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers according to claim 3, characterized in that: In step (4), the steel plate with a thickness of ≥10 mm is subjected to two-stage controlled rolling, the total rolling passes in the recrystallization zone are 4 times, the cumulative reduction rate in the recrystallization zone is ≥40%, the final rolling temperature is 820°C-860°C, the red-returning temperature after rolling is 730-760°C, the cooling rate is controlled at 20-30°C / s, and the microstructure of the rolled steel plate is refined.

7. The method for producing 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers according to claim 3, characterized in that: In step (5), the quenching temperature is 870-910°C, the total time in the furnace is 2.0±1min / mm×steel plate thickness / mm, and the steel is water-cooled to room temperature; the tempering temperature is 590-620°C, the total heating time is 3.25±1min / mm×steel plate thickness / mm, and the steel is air-cooled to room temperature.

8. The method for producing 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers according to claim 3, characterized in that: The thickness of the steel plates produced is 5mm-80mm.

9. The method for producing 11MnNiMoDR ​​medium and thick plates for high-strength ultra-low temperature containers according to claim 3, characterized in that: The structure of the steel plate produced is tempered troostite + ferrite, the grain size is grade 8.0, the yield strength is ≥440MPa, the tensile strength is ≥570MPa, the elongation after fracture is ≥20%, and the average impact energy at -100℃ is ≥120J.

Images