A 800MPa grade quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate and its preparation method

Abstract

The present invention discloses an 800MPa grade quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate and a preparation method thereof; it belongs to the field of container steel manufacturing, and its chemical composition weight percentage is: C, Si, Mn, P, S, Ni, Cr, Mo, V, Ti, Als and B, and the balance is Fe and inevitable impurity elements; its preparation method is: the steel billet is successively subjected to smelting and continuous casting processes to produce a continuous casting billet of the target composition; the continuous casting billet is successively subjected to heating, rolling, heat treatment, inspection and warehousing processes. The present invention adopts a new Ni-Cr-Mo component design system to ensure its good hydrogen embrittlement resistance, and produces a ≤80mm thick 800MPa grade hydrogen-resistant pressure vessel high-strength tempered extra-thick plate through a reasonable offline quenching + high-temperature tempering heat treatment process, breaking through the bottleneck of the existing technology, meeting the user's high strength and toughness requirements for quenched and tempered extra-thick plates for hydrogen-resistant pressure vessels, and improving the service safety of pressure vessels. At the same time, it also lays the foundation for the development, production and application of a new generation of hydrogen-resistant quenched and tempered high-strength pressure vessel steel.

Description

Technical Field

[0001] The invention belongs to the field of container steel manufacturing, and relates to an 800MPa grade quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate and a preparation method thereof. Background Art

[0002] Among the existing hydrogen storage technologies, high-pressure gaseous hydrogen storage technology has high maturity and low cost, and is currently the most suitable technical solution for large-scale storage and transportation. This technical solution requires the construction of 100 cubic meters of high-pressure hydrogen storage tanks, hundreds of kilometers of high-pressure hydrogen pipelines, etc. For large-scale hydrogen storage and transportation needs, materials suitable for high-pressure hydrogen storage and transportation equipment are core technologies that must be broken through. The most critical technical features of this type of material are: high strength, weldability, good strength and toughness matching, and resistance to hydrogen corrosion and hydrogen embrittlement. At present, pressure vessel equipment is developing towards high parameters and large-scale. For safety reasons, the limit specifications and strength and toughness requirements of pressure vessel steel are also increasing. In terms of the physical level of steel plates, most domestic ultra-high-strength steel plates for pressure vessels not only lack data support for hydrogen resistance, but also have shortcomings such as narrow thickness specification range, poor surface quality, and low impact toughness, which cannot meet the current large-scale high-parameter hydrogen-resistant pressure vessels. Use requirements.

[0003] For example, the patent with publication number CN104532159A discloses "a quenched and tempered high-strength steel with a yield strength of 700MPa and a production method thereof", whose chemical composition includes C, Si, Mn, Cr, Mo, Ni, Nb, Ti, V, B, Al, Ca, N, P, S and O, and the rest are Fe and inevitable impurities; the actual yield strength of the steel plate in this patent is 700-850MPa, and the tensile strength is 750-900MPa. Although the strength is relatively high, the elongation is only >14%, and the impact energy at -40℃ is only >40J. The plastic toughness of the steel plate is relatively low.

[0004] For example, the patent with publication number CN109112421A discloses "a steel 07Cr2AlMoR for pressure vessels and its production method", whose chemical composition includes C, Mn, Cr, Mo, Alt, S, P and Si, and the rest is Fe and other inevitable impurities; although the production method disclosed in the patent has a wide range of steel plate thickness specifications, up to 80mm, but the actual strength and toughness level of the steel plate is low, with a tensile strength of less than 500MPa, an impact toughness of less than 100J and a quality grade of only D.

[0005] Another example is the patent with publication number CN115261714A, which discloses "a steel for pressure vessels and its preparation method", whose chemical composition includes C, Si, Mn, P, S, Al, V, Nb, N, Cu, Sn, Sb and Mg; the rest are Fe and other unavoidable impurities. The patent only discloses the production method of relatively thin steel plates with a thickness of ≤55mm, but the production method of thicker steel plates is not mentioned, which cannot meet the application performance requirements of extra-thick plates. At the same time, none of the above patents mention the hydrogen resistance of the steel plates. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide an 800MPa grade quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate and a preparation method thereof.

[0007] Technical solution: The 800MPa grade quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of the present invention has the following chemical compositions by weight percentage: C: 0.07-0.13%, Si: 0.10-0.45%, Mn: 0.80-1.50%, P≤0.012%, S≤0.005%, Ni: 0.60-1.50%, Cr: 0.25-0.80%, Mo: 0.30-0.70%, V: 0.01-0.05%, Ti≤0.030%, Als: ≤0.05%, B: 0.0005-0.0030%, and the balance is Fe and unavoidable impurity elements;

[0008] The chemical composition of the steel plate is as follows by weight percentage: C: 0.07%, Si: 0.12%, Mn: 0.93%, P: 0.011%, S: 0.005%, Ni: 0.61%, Cr: 0.27%, Mo: 0.32%, V: 0.015%, Ti: 0.017%, Als: 0.031%, B: 0.0007%, and the balance is Fe and unavoidable impurity elements;

[0009] The chemical composition of the steel plate is as follows by weight percentage: C: 0.09%, Si: 0.23%, Mn: 0.99%, P: 0.010%, S: 0.004%, Ni: 0.88%, Cr: 0.47%, Mo: 0.47%, V: 0.022%, Ti: 0.019%, Als: 0.037%, B: 0.0014%, and the balance is Fe and unavoidable impurity elements;

[0010] The chemical composition of the steel plate is as follows by weight percentage: C: 0.11%, Si: 0.29%, Mn: 1.18%, P: 0.009%, S: 0.003%, Ni: 0.99%, Cr: 0.78%, Mo: 0.56%, V: 0.039%, Ti: 0.021%, Als: 0.040%, B: 0.0026%, and the balance is Fe and unavoidable impurity elements;

[0011] The chemical composition of the steel plate is as follows by weight percentage: C: 0.12%, Si: 0.36%, Mn: 1.33%, P: 0.010%, S: 0.003%, Ni: 1.17%, Cr: 0.65%, Mo: 0.60%, V: 0.045%, Ti: 0.023%, Als: 0.040%, B: 0.0028%, and the balance is Fe and unavoidable impurity elements;

[0012] The chemical composition of the steel plate is as follows by weight percentage: C: 0.13%, Si: 0.43%, Mn: 1.45%, P: 0.011%, S: 0.004%, Ni: 1.46%, Cr: 0.63%, Mo: 0.67%, V: 0.047%, Ti: 0.029%, Als: 0.047%, B: 0.0027%, and the balance is Fe and unavoidable impurity elements;

[0013] A method for preparing an 800MPa grade quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate, wherein a steel billet having the same composition as the steel is subjected to smelting and continuous casting processes in sequence to produce a continuous casting billet with a target composition; the continuous casting billet is subjected to heating, rolling, heat treatment, inspection, warehousing and other processes in sequence; the specific preparation steps are as follows:

[0014] (1): The smelting process includes molten iron pretreatment, top and bottom double blowing converter, LF refining and RH refining, wherein the final temperature of converter smelting is 1600-1650°C to ensure carbon pulling and no phosphorus regeneration in the later stage; LF refining adopts aluminum deoxidation, the total time is 40-45 minutes, and the atmosphere in the ladle is controlled by micro-positive pressure operation throughout the process; seamless pure calcium wire is fed at the end of RH; ferroboron is added after uniformity, and static stirring is performed after wire feeding is completed, and the static stirring time is 25-30 minutes to ensure that the slag surface fluctuates without crusting and the molten steel is not exposed;

[0015] (2): The continuous casting process adopts slab light pressure reduction and electromagnetic stirring technology to reduce center segregation and looseness, and the pressure is reduced by 5 to 7 mm at the end of solidification. Protective casting is adopted in the continuous casting process to prevent secondary oxidation of molten steel;

[0016] (3): The continuous casting billet heating process: the heating temperature is 1150-1280°C, and the total time coefficient in the furnace is 1.0-1.2 min / mm, so as to ensure that a uniform original austenite structure is obtained inside the steel;

[0017] (4): The rolling process adopts a controlled rolling and controlled cooling process, which is a two-stage controlled rolling, i.e., rolling in the austenite recrystallization zone and the austenite non-recrystallization zone, with a total compression ratio of not less than 4 times: the starting temperature of the rough rolling is ≥1000°C, and a large reduction method is adopted in this stage; the starting temperature of the finishing rolling is 810-880°C, and in this stage, sufficient deformation is ensured so that the austenite grains are stretched and deformed along the rolling direction. At the same time, through the addition of micro-alloying elements such as Ti and V, carbonitride particles are precipitated by strain during the deformation process, which pins the austenite grains to prevent them from growing, thereby refining the structure after the phase transformation; the final rolling temperature is 800-850°C; after rolling, laminar cooling is performed, the red-return temperature is 600-680°C, and then air cooling is performed to room temperature;

[0018] (5): The heat treatment process includes quenching and tempering processes, wherein the quenching temperature of the steel plate is 850-930°C, and the holding time coefficient is 1.3-1.8 min / mm. Subsequently, the tempering process is used to eliminate the residual stress caused by quenching and homogenize the structure to obtain stable and excellent comprehensive properties. The tempering temperature of the steel plate is 610-670°C, and the holding time coefficient is 2.0-4.0 min / mm.

[0019] The ultra-high strength hydrogen-resistant steel plate for pressure vessels of the present invention has a thickness of 12 to 80 mm, a final structure of the steel plate mainly composed of bainite, and excellent physical properties of the steel plate: the hydrogen embrittlement index of the steel plate in a 25 MPa hydrogen environment is ≥0.75, the internal flaw detection reaches NB / T 47013.3TI level, the tensile strength of the steel plate is Rm800 to 900 MPa, the elongation A is ≥17%, and the -40°C KV2 is ≥100 J.

[0020] Beneficial effects: Compared with the prior art, the present invention is characterized by: 1. Through the calculation of material hydrogen resistance and chemical composition design based on the first principles, the good hydrogen resistance of the steel plate is ensured, and 12-80 mm thick steel plates are produced. The thickness specification covers a wide range, has better strength, toughness and plasticity, and the hydrogen embrittlement index of the steel plate under a 25MPa hydrogen environment is ≥0.75, the tensile strength Rm is 800-900MPa, the elongation A is ≥17%, and the -40℃ KV2 is ≥100J; 2. Through the production process (smelting, continuous casting, rolling, heat treatment process, etc.), the internal quality and performance stability of the steel plate are improved, and the steel plate has excellent comprehensive mechanical properties; 3. It breaks through the bottleneck of the existing technology and fills the technical gap of materials for large-scale high-pressure vessels in China. In the later stage, it will promote the formation of a series of specifications and preparation, storage and transportation and terminal application of pressure vessel equipment, materials, design, construction, application, safety evaluation and other complete and efficient industrial chain prototypes, laying the foundation for the development, production and application of a new generation of tempered high-strength pressure vessel steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an OM diagram of the microstructure of the steel plate for ultra-high strength hydrogen resistant pressure vessel in the embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] Embodiment 1:

[0024] 1. The quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment has a thickness of 12 mm. Its chemical composition and mass percentage are shown in Table 1.

[0025] 2. The method for preparing the quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment includes smelting, continuous casting, heating of the ingot, rolling, and heat treatment processes. The specific process steps are as follows:

[0026] (1): Smelting process: including molten iron pretreatment, top and bottom double blowing converter, LF refining and RH refining, wherein the converter smelting end temperature is 1610℃, the total time is 42min, and the atmosphere in the ladle is controlled by micro positive pressure operation throughout the process; seamless pure calcium wire is fed after RH is finished; ferroboron is added after uniformity, and static stirring is performed after wire feeding is completed, and the static stirring time is 26min;

[0027] (2): In the continuous casting process, the slab is gently pressed down and electromagnetic stirring technology is used to reduce center segregation and looseness, and the pressure at the end of solidification is 6.1 mm;

[0028] (3): Continuous casting billet heating process: heating temperature is 1150℃, total time coefficient in the furnace is 1.0min / mm;

[0029] (4): Rolling process: controlled rolling and controlled cooling process: the starting temperature of rough rolling is 1050℃; the starting temperature of finishing rolling is 815℃, and the final temperature of finishing rolling is 800℃; after rolling, laminar cooling is performed, the red-returning temperature is 680℃, and then air cooling is performed to room temperature;

[0030] (5): Heat treatment process: including quenching and tempering processes, in which the quenching temperature of the steel plate is 850℃, the holding time coefficient is 1.6min / mm; the tempering temperature is 610℃, and the holding time coefficient is 4.0min / mm.

[0031] 3. The quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment meets the requirements of NB / T 47013.3TI-level ultrasonic flaw detection; the actual performance of the product is shown in Table 2.

[0032] Embodiment 2:

[0033] 1. The quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment has a thickness of 20 mm. Its chemical composition and mass percentage are shown in Table 1.

[0034] 2. The method for preparing the quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment includes smelting, continuous casting, heating of the ingot, rolling, and heat treatment processes. The specific process steps are as follows:

[0035] (1): Smelting process: including molten iron pretreatment, top and bottom double blowing converter, LF refining and RH refining, wherein the converter smelting end temperature is 1645℃, the total time is 43min, and the atmosphere in the ladle is controlled by micro positive pressure operation throughout the process; seamless pure calcium wire is fed after RH is finished; ferroboron is added after uniformity, and static stirring is performed after wire feeding is completed, and the static stirring time is 27min;

[0036] (2): In the continuous casting process, the slab is gently pressed down and electromagnetic stirring technology is used to reduce center segregation and looseness, and the pressure at the end of solidification is 6.7 mm;

[0037] (3): Continuous casting billet heating process: heating temperature is 1185℃, total time coefficient in the furnace is 1.2min / mm;

[0038] (4): Rolling process: controlled rolling and controlled cooling process: the starting temperature of rough rolling is 1030℃; the starting temperature of finishing rolling is 865℃, and the final rolling temperature of finishing rolling is 820℃; after rolling, laminar cooling is performed, the return temperature is 665℃, and then air cooling is performed to room temperature;

[0039] (5): Heat treatment process: including quenching and tempering processes, in which the quenching temperature of the steel plate is 875℃, and the holding time coefficient is 1.3min / mm; the tempering temperature is 670℃, and the holding time coefficient is 3.5min / mm.

[0040] 3. The quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment meets the requirements of NB / T 47013.3TI-level ultrasonic flaw detection; the actual performance of the product is shown in Table 2.

[0041] Embodiment 3:

[0042] 1. The quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment has a thickness of 40 mm. Its chemical composition and mass percentage are shown in Table 1.

[0043] 2. The method for preparing the quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment includes smelting, continuous casting, heating of the ingot, rolling, and heat treatment processes. The specific process steps are as follows:

[0044] (1): Smelting process: including molten iron pretreatment, top and bottom double blowing converter, LF refining and RH refining, wherein the converter smelting end temperature is 1627℃, the total time is 41min, and the atmosphere in the ladle is controlled by micro positive pressure operation throughout the process; seamless pure calcium wire is fed after RH is finished; ferroboron is added after uniformity, and static stirring is performed after wire feeding is completed, and the static stirring time is 26min;

[0045] (2): In the continuous casting process, the slab is gently pressed down and electromagnetic stirring technology is used to reduce center segregation and looseness, and the pressure at the end of solidification is 5.2 mm;

[0046] (3): Continuous casting billet heating process: heating temperature is 1220℃, total time coefficient in the furnace is 1.0min / mm;

[0047] (4): Rolling process: controlled rolling and controlled cooling process: the starting temperature of rough rolling is 1045℃; the starting temperature of finishing rolling is 875℃, and the final temperature of finishing rolling is 840℃; after rolling, laminar cooling is performed, the red-returning temperature is 680℃, and then air cooling is performed to room temperature;

[0048] (5): Heat treatment process: including quenching and tempering processes, in which the quenching temperature of the steel plate is 925℃, and the holding time coefficient is 1.5min / mm; the tempering temperature is 650℃, and the holding time coefficient is 2.0min / mm.

[0049] 3. The quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment meets the requirements of NB / T 47013.3TI-level ultrasonic flaw detection; the actual performance of the product is shown in Table 2.

[0050] Embodiment 4:

[0051] 1. The quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment has a thickness of 72 mm. Its chemical composition and mass percentage are shown in Table 1.

[0052] 2. The method for preparing the quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment includes smelting, continuous casting, heating of the ingot, rolling, and heat treatment processes. The specific process steps are as follows:

[0053] (1): Smelting process: including molten iron pretreatment, top and bottom double blowing converter, LF refining and RH refining, wherein the converter smelting end temperature is 1637℃, the total time is 44min, and the atmosphere in the ladle is controlled by micro positive pressure operation throughout the process; seamless pure calcium wire is fed after RH is finished; ferroboron is added after uniformity, and static stirring is performed after wire feeding is completed, and the static stirring time is 29min;

[0054] (2): In the continuous casting process, the slab is gently pressed down and electromagnetic stirring technology is used to reduce center segregation and looseness, and the pressure at the end of solidification is 5.8 mm;

[0055] (3): Continuous casting billet heating process: heating temperature is 1253℃, total time coefficient in the furnace is 1.2min / mm;

[0056] (4): Rolling process: controlled rolling and controlled cooling process: the starting temperature of rough rolling is 1050℃; the starting temperature of finishing rolling is 875℃, and the final temperature of finishing rolling is 830℃; after rolling, laminar cooling is performed, the red-returning temperature is 630℃, and then air cooling is performed to room temperature;

[0057] (5): Heat treatment process: including quenching and tempering processes, in which the quenching temperature of the steel plate is 890℃, the holding time coefficient is 1.8min / mm; the tempering temperature is 630℃, and the holding time coefficient is 3.0min / mm.

[0058] 3. The quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment meets the requirements of NB / T 47013.3TI-level ultrasonic flaw detection; the actual performance of the product is shown in Table 2.

[0059] Embodiment 5:

[0060] 1. The quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment has a thickness of 80 mm. Its chemical composition and mass percentage are shown in Table 1.

[0061] 2. The method for preparing the quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment includes smelting, continuous casting, heating of the ingot, rolling, and heat treatment processes. The specific process steps are as follows:

[0062] (1): Smelting process: including molten iron pretreatment, top and bottom double blowing converter, LF refining and RH refining, wherein the converter smelting end temperature is 1642℃, the total time is 45min, and the atmosphere in the ladle is controlled by micro positive pressure operation throughout the process; seamless pure calcium wire is fed after RH is finished; ferroboron is added after uniformity, and static stirring is performed after wire feeding is completed, and the static stirring time is 28min;

[0063] (2): In the continuous casting process, the slab is gently pressed down and electromagnetic stirring technology is used to reduce center segregation and looseness, and the pressure at the end of solidification is 6.3mm;

[0064] (3): Continuous casting billet heating process: heating temperature is 1275℃, total time coefficient in the furnace is 1.1min / mm;

[0065] (4): Rolling process: controlled rolling and controlled cooling process: the starting temperature of rough rolling is 1040℃; the starting temperature of finishing rolling is 880℃, and the final temperature of finishing rolling is 850℃; after rolling, laminar cooling is performed, the red-returning temperature is 630℃, and then air cooling is performed to room temperature;

[0066] (5): Heat treatment process: including quenching and tempering processes, in which the quenching temperature of the steel plate is 910℃, the holding time coefficient is 1.6min / mm; the tempering temperature is 645℃, and the holding time coefficient is 3.0min / mm.

[0067] 3. The quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate of this embodiment meets the requirements of NB / T 47013.3TI-level ultrasonic flaw detection; the actual performance of the product is shown in Table 2.

[0068] Table 1 Chemical composition mass percentage (wt.%)

[0069]

[0070] Table 2 Physical properties

[0071]

[0072]

[0073] In order to improve the strength and toughness of domestic quenched and tempered high-strength steel plates for hydrogen-resistant pressure vessels, while focusing on improving the ultimate specifications of steel plates, breaking through existing technical bottlenecks, designing and developing a new generation of high-performance quenched and tempered high-strength steel plates for pressure vessels, filling the technical gap in materials for large high-pressure vessels, reasonable chemical composition design and heat treatment process matching are the technical keys; finally, the Ni-Cr-Mo series hydrogen-resistant component system and multi-element (micro) alloying technology are adopted, and precipitation strengthening, solid solution strengthening and fine grain strengthening effects are utilized, supplemented by appropriate rolling and heat treatment processes, to develop and produce steel for hydrogen-resistant pressure vessels with excellent toughness and thickness of ≤80mm, aiming to realize the engineering demonstration application of the first 100-cubic-meter-level large-scale high-pressure hydrogen storage container in China. The actual level of the steel plate is ≥0.75 for the hydrogen embrittlement index of the steel plate in a 25MPa hydrogen environment, and the internal flaw detection reaches NB / T 47013.3TI level, with a tensile strength of Rm800~900MPa, an elongation of A≥17%, and a KV2≥100J at -40℃.

[0074] The steel plate used in the present invention is mainly used in the construction of high-pressure hydrogen storage containers. The new Ni-Cr-Mo component design system is adopted to ensure its good resistance to hydrogen embrittlement. Through a reasonable offline quenching + high-temperature tempering heat treatment process, a high-strength tempered extra-thick plate with a thickness of ≤80mm and 800MPa grade hydrogen-resistant pressure vessels is produced, breaking through the bottleneck of the existing technology, meeting the high strength and toughness requirements of the tempered extra-thick plate for hydrogen-resistant pressure vessels, improving the service safety of the pressure vessels, and also laying the foundation for the development, production and application of a new generation of hydrogen-resistant tempered high-strength pressure vessel steel.

[0075] The present invention discloses an 800MPa grade quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate and a preparation method thereof. The steel plate has the comprehensive properties of high strength and toughness, high plasticity and excellent hydrogen embrittlement resistance. The produced steel plate is of great significance for the construction of large-scale high-pressure hydrogen storage containers.

Claims

1. An 800MPa grade quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate, characterized in that: The thickness of the steel plate is 12 mm, and the chemical composition of the steel plate is as follows by weight percentage: C: 0.07%, Si: 0.12%, Mn: 0.93%, P: 0.011%, S: 0.005%, Cr: 0.27%, Mo: 0.32%, Ni: 0.61%, V: 0.015%, Ti: 0.017%, Als: 0.031%, B: 0.0007%, and the balance is Fe and unavoidable impurity elements; The preparation method includes smelting, continuous casting, heating of ingot, rolling and heat treatment. The specific process is as follows: (1): Smelting process: including molten iron pretreatment, top and bottom double blowing converter, LF refining and RH refining, wherein the converter smelting end temperature is 1610℃, the total time is 42min, and the atmosphere in the ladle is controlled by micro positive pressure operation throughout the process; seamless pure calcium wire is fed after RH is finished; ferroboron is added after uniformity, and static stirring is performed after wire feeding is completed, and the static stirring time is 26min; (2): In the continuous casting process, the slab is gently pressed down and electromagnetic stirring technology is used to reduce center segregation and looseness, and the pressure at the end of solidification is 6.1 mm; (3): Continuous casting billet heating process: heating temperature is 1150℃, total time coefficient in the furnace is 1.0min / mm; (4): Rolling process: controlled rolling and controlled cooling process: the starting temperature of rough rolling is 1050℃; the starting temperature of finishing rolling is 815℃, and the final temperature of finishing rolling is 800℃; after rolling, laminar cooling is performed, the return temperature is 680℃, and then air cooling is performed to room temperature; (5): Heat treatment process: including quenching and tempering processes, where the quenching temperature of the steel plate is 850℃, the holding time coefficient is 1.6min / mm; the tempering temperature is 610℃, and the holding time coefficient is 4.0min / mm; Its physical properties: R eL / R p0.2 :823 Mpa; R m :851 Mpa;A:17.5%; -40℃Akv / J: 109 132 109; the average value is:

117.

2. An 800MPa grade quenched and tempered ultra-high strength hydrogen-resistant pressure vessel steel plate, characterized in that: The thickness of the steel plate is 20 mm, and the chemical composition of the steel plate is as follows by weight percentage: C: 0.09%, Si: 0.23%, Mn: 0.99%, P: 0.010%, S: 0.004%, Cr: 0.47%, Mo: 0.47%, Ni: 0.88%, V: 0.022%, Ti: 0.019%, Als: 0.037%, B: 0.0014%, and the balance is Fe and unavoidable impurity elements; The preparation method includes smelting, continuous casting, heating of ingot, rolling and heat treatment. The specific process is as follows: (1): Smelting process: including molten iron pretreatment, top and bottom double blowing converter, LF refining and RH refining, wherein the converter smelting end temperature is 1645℃, the total time is 43min, and the atmosphere in the ladle is controlled by micro positive pressure operation throughout the process; seamless pure calcium wire is fed after RH is finished; ferroboron is added after uniformity, and static stirring is performed after wire feeding is completed, and the static stirring time is 27min; (2): In the continuous casting process, the slab is gently pressed down and electromagnetic stirring technology is used to reduce center segregation and looseness, and the pressure at the end of solidification is 6.7 mm; (3): Continuous casting billet heating process: heating temperature is 1185℃, total time coefficient in the furnace is 1.2min / mm; (4): Rolling process: controlled rolling and controlled cooling process: the starting temperature of rough rolling is 1030℃; the starting temperature of finishing rolling is 865℃, and the final temperature of finishing rolling is 820℃; after rolling, laminar cooling is performed, the return temperature is 665℃, and then air cooling is performed to room temperature; (5): Heat treatment process: including quenching and tempering processes, where the quenching temperature of the steel plate is 875℃, the holding time coefficient is 1.3min / mm; the tempering temperature is 670℃, and the holding time coefficient is 3.5min / mm; Its physical properties: R eL / R p0.2 :796 Mpa; R m : 848 Mpa; A: 18.5%; -40℃Akv / J: 143 128 140; the average value is: 137.

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