Thick steel plate for 1300MPa grade pressure-bearing equipment, manufacturing, forming and post-heat treatment method

Abstract

The present invention provides a 1300MPa thick steel plate for pressure-bearing equipment, a manufacturing method, a forming method and a subsequent heat treatment method. The composition of the steel plate is as follows by weight percentage: C 0.19% to 0.23%, Si 0.10% to 0.40%, Mn 0.40% to 0.70%, P≤0.010%, S≤0.003%, Cr 1.40% to 2.0%, Mo 0.40% to 0.60%, B 0.001% to 0.005%, Alt 0.015% to 0.045%, and the balance is Fe and unavoidable inclusions. The manufacturing method includes smelting, continuous casting, heating, controlled rolling, controlled cooling and tempering; the steel after forming and heat treatment has a room temperature mechanical property of 950MPa≤R p0.2 ≤1100MPa, 1300MPa≤Rm≤1430MPa, elongation A≥19%; at 400℃, 560MPa≤Rp 0.2 ≤630MPa; impact energy KV2≥120J at 0℃; ensure the use requirements of high-strength pressure-bearing equipment.

Description

Technical Field

[0001] The invention belongs to the field of metal materials, and in particular relates to a thick steel plate for 1300MPa-level pressure-bearing equipment, and a manufacturing, forming and subsequent heat treatment method thereof. Background Art

[0002] As an important place for product storage, medium reaction or heat exchange, pressure equipment is widely used in the processing and preparation of bulk energy such as coal power and chemical industry, and plays an important role in the entire energy production process. For example, the fierce medium reaction process in chemical plants produces huge internal pressure, and the air pressure generated in the steam heat delivery process of coal power plants. Pressure equipment is subjected to huge pressure in its process. For high-power equipment, the pressure it withstands can reach more than 100MPa. The special equipment industry defines this as ultra-high pressure, and the tensile strength of steel used to manufacture such equipment needs to reach 1300MPa. In recent years, in order to meet the rapid development of this type of pressure equipment manufacturing industry, pressure equipment with high efficiency, high parameters and high reliability design requirements has been proposed by design institutes, and the existing strength level of metal materials used for pressure equipment can no longer meet the design requirements, and ultra-high strength and toughness materials are needed to support the development of high-end equipment.

[0003] The disclosed invention patent "A steel for nuclear power pressure equipment and its manufacturing method" (publication number CN103160732A) is for pressure equipment steel used in the nuclear power field, and its tensile strength is 560-625N / mm2. 2 Within the range, the tensile strength after simulated post-weld heat treatment is reduced to 510-600N / mm 2 When facing a higher pressure service environment, the product cannot provide the higher strength support equipment requirements, especially there is no technical solution and data after molding to support its sufficient strength to meet the high pressure service requirements.

[0004] The disclosed invention patent "A hot-rolled weldable steel plate for pressure-bearing equipment and its production method" (publication number CN110983175A), judging from the disclosed composition, production method and beneficial effects, this patented product is used for automobile manufacturing and involves ultra-thin specifications with a thickness of 2 to 4 mm. It is not suitable for the manufacture of pressure-bearing equipment, and the relevant technical solutions and data after forming support its manufacture of pressure-bearing equipment.

[0005] The disclosed invention patent "A hot-rolled weldable steel plate for pressure-bearing equipment and its production method" (publication number CN110983175A) is used as steel for pressure-bearing equipment based on the disclosed composition, production method and beneficial effects. The tensile strength of the product in the as-sold state and the simulated post-weld heat treatment state is in the range of 450-610MPa, and the microstructure is ferrite and pearlite. When facing a service environment with higher pressure and higher temperature, the organization and performance of the product can no longer meet the application requirements.

[0006] The disclosed invention patent "A thick ultra-high-strength steel plate with a tensile strength of 1300MPa and its manufacturing method" (publication number CN 105039866A) shows that, based on the disclosed composition, production method and beneficial effects, this patented product is suitable for the field of engineering machinery, and the maximum thickness specification reaches 50mm. There is no process embodiment and performance indicators in the forming and manufacturing of pressure-bearing equipment.

[0007] The comprehensive performance and forming performance of the high-strength steel plates for pressure-bearing equipment of the above invention and existing ones can no longer meet the development needs of new energy equipment. Therefore, there is an urgent need to develop 1300MPa-grade (40-80) mm thick high-strength key materials for pressure-bearing equipment that can meet the requirements of room temperature strength, high temperature strength, forming performance and excellent post-weld heat treatment performance to support the development needs of my country's large-scale new energy pressure-bearing equipment or equipment. Summary of the invention

[0008] The purpose of the present invention is to overcome the problem that the above-mentioned inventions are insufficient in strength or cannot provide a technical solution to improve the strength of high-strength pressure-bearing equipment after forming, and to provide a steel plate with a thickness specification of (40 to 80) mm and a steel product for pressure-bearing equipment with a tensile strength of 1300 MPa after forming, as well as manufacturing, forming and subsequent heat treatment processes to meet the manufacturing needs of ultra-high-strength pressure-bearing equipment.

[0009] The object of the invention is achieved in this way:

[0010] A thick steel plate for 1300MPa grade pressure-bearing equipment, the components of the steel plate are as follows by weight percentage: C 0.19%-0.23%, Si 0.10%-0.40%, Mn 0.40%-0.70%, P≤0.010%, S≤0.003%, Cr 1.40%-2.0%, Mo 0.40%-0.60%, B 0.001%-0.005%, Alt 0.015%-0.045%, and the balance is Fe and unavoidable inclusions.

[0011] The thickness of the thick steel plate for pressure equipment is 40-80mm; the mechanical properties of the thick steel plate for pressure equipment are 930MPa≤R p0.2 ≤1080MPa、1300MPa≤R m≤1430MPa; Impact energy KV at 0℃ 2 ≥100J.

[0012] The reasons for the composition design of the present invention are as follows:

[0013] C is the most important element for improving the strength of steel. The hardenability of steel is significantly improved by adding C. In addition, the C of the present invention combines with the strong carbide alloying elements in the steel to play a precipitation strengthening role, obtain a secondary hardening effect, and ensure the high strength requirements of the steel. When the carbon content is lower than 0.13%, the hardenability is low, and it is difficult to obtain a uniform sorbite structure in the subsequent tempering treatment, and the strength of the steel cannot meet the use requirements. However, too high a carbon content will affect the machining performance of the steel, so the present invention limits the C content range to 0.19% to 0.23%.

[0014] Si acts as a reducing agent and deoxidizer in the steelmaking process. Si has a certain effect on the martensite transformation during tempering. When the silicon content is higher than 0.5%, it will hinder the activity of C in martensite during tempering, causing ε carbide to form in martensitic steel instead of M. 3 C-type carbides reduce the hardness and toughness of steel and increase the sensitivity to temper brittleness, so the present invention limits the Si content range to 0.10% to 0.40%.

[0015] Mn is an element that strongly stabilizes austenite, can effectively reduce the decomposition rate of austenite, improve the hardenability of steel, and can strongly increase the strength and hardness of steel. However, a high Mn content will enhance the temper brittleness of steel. Therefore, the present invention limits the Mn content range to 0.40% to 0.70%.

[0016] S and P are harmful elements in steel and must be strictly controlled to ensure the purity and plasticity of the steel. Therefore, the present invention limits S to ≤ 0.003% and P to ≤ 0.010%.

[0017] Adding a certain amount of Cr to Cr steel significantly improves the hardenability of the steel and ensures the matrix strength of the steel. In addition, Cr is a strong carbide-forming element. It forms stable carbides with C in steel, which improves the pressure-bearing capacity of pressure-bearing equipment. When the Cr content is lower than 0.3%, the hardenability is improved very little, which is not conducive to the formation of lath martensite structure and cannot meet the high-strength performance requirements of steel. Therefore, the present invention limits the Cr content range to 1.40% to 2.00%.

[0018] Mo can improve the hardenability of steel, effectively refine austenite grains, and strengthen the solid solution strengthening effect of ferrite. The addition of a certain amount of Mo can improve the tempering resistance of steel and inhibit tempering embrittlement. At the same time, molybdenum is a strong carbide-forming element, and the carbide formed during tempering has a secondary hardening effect. Therefore, the present invention limits the Mo content range to 0.40% to 0.60%.

[0019] B increases the hardenability of steel and utilizes the high-hardness boride formed by boron to improve the strength of steel. However, a boron content exceeding 0.007% will cause hot brittleness of the steel and affect the forming and processing performance of the pressure-bearing equipment. The present invention limits the B content range to 0.001% to 0.005%.

[0020] Alt is a commonly used deoxidizer in steel. Adding a small amount of aluminum can refine the grains and improve the strength and impact toughness of steel. Too high an amount will affect the hot working properties, welding properties and cutting properties of steel. The present invention limits the Alt content range to 0.015% to 0.045%.

[0021] The second technical solution of the present invention is to provide a method for manufacturing a 1300MPa grade thick steel plate for pressure-bearing equipment, including smelting, continuous casting, heating, controlled rolling, controlled cooling, and tempering;

[0022] Smelting: The smelting of molten steel is carried out in a converter, using high-quality scrap steel and molten iron as raw materials, and the molten iron content is controlled at 75% to 85%. At the same time, in order to effectively reduce the content of harmful elements P, dephosphorization and decarburization are smelted separately in a converter, wherein the oxygen blowing for dephosphorization is controlled at 7 to 10 minutes, and the oxygen blowing for decarburization is controlled at 8 to 12 minutes, and finally the mass fraction of phosphorus is reduced to less than 0.006%; deep desulfurization treatment is carried out in the LF refining furnace, and the sulfur content is controlled below 0.002%; degassing is completed in the VD furnace, with a net cycle time of 10 to 15 minutes and a calming time of 3 to 5 minutes before pouring.

[0023] Continuous casting: After breaking the vacuum, the slab continuous casting machine is used for casting, the superheat is set to 20-30℃, and the casting rate is 1.0-1.4m / min. The billet is stacked and slowly cooled down after it comes off the line. The stacking slow cooling time is 24-36h, and the stacking is unstacked below 400℃ to prevent defects such as cracks in the billet caused by rapid cooling.

[0024] Heating: The heating temperature is controlled at 1180-1230°C, and the total heating time is 4.0-6.0 hours.

[0025] Controlled rolling: The rolling adopts a two-stage controlled rolling method. The end temperature of the recrystallization zone rolling is ≥1000℃. In order to fully break up the core structure of the steel billet, the total deformation rate is ≥50%. The starting rolling temperature of the non-recrystallization zone is 870~930℃, the final rolling temperature is 830~870℃, and the total deformation rate is ≥55%. At this time, the austenite grains are further flattened and elongated. With the increase of the grain boundary area, the ferrite nucleation rate increases in the subsequent phase transformation process, and the grains are fully refined. The target thickness of the rolled piece is 40~80mm.

[0026] Controlled cooling: In order to further refine the internal structure of thick-gauge steel plates, the steel plates are rolled using a controlled cooling process with a cooling temperature of 780-820°C, a cooling rate of 30-55°C / s, and a return to red temperature of 450-500°C.

[0027] Tempering: Since more solid solution strengthening elements such as C, Mn, Cr, and Mo are added to the steel, the steel plate can obtain a lath martensite structure with ultra-high strength and hardness after rolling. However, the grain size of the steel plate is coarse, and there is concentration of structural stress and thermal stress, which is prone to delayed cracking during flame cutting. Therefore, heat treatment should be used in time to soften and eliminate stress. The present invention uses tempering heat treatment to ensure that the strength of the pressure-bearing steel plate is not lost, while making the steel plate have suitable plastic toughness, which is conducive to the forming processing of the steel plate. Therefore, the tempering heat treatment temperature of the steel is 650-700°C, and the insulation is 2.0-4.0min / mm.

[0028] The third technical solution of the present invention is to provide a forming process for thick steel plates for 1300MPa-level pressure-bearing equipment; forming is a necessary process for steel plates to pressure-bearing equipment. Therefore, the forming heat treatment process is crucial to how the steel plate can meet its designed bearing pressure after manufacturing the pressure-bearing equipment. The present invention has formulated the optimal forming heat treatment process for steel. The parameters and reasons are set as follows: the forming process is 930-960℃ insulation, the insulation time is 1.0-2.0min / mm, and after being taken out of the furnace, it enters the salt water bath and cools to room temperature. In this process, the chemical elements C, Mn, Cr, Mo and the alloy element B enter the austenite zone. After a period of insulation, the alloy elements are dissolved in the austenite matrix, and then enter the salt water bath at 0-10℃ and rapidly cool at 35-55℃ / s to transform into a fine lath martensite structure. At this time, the steel has ultra-high strength to meet the needs of pressure-bearing equipment. However, the plasticity and toughness of the steel are poor and the organizational stress is high at this time. Through short-time tempering heat treatment at 370-400℃ and insulation for 0.5-1.0h, the quenching stress can be eliminated in time, the organization can be softened, the plasticity and toughness of the steel can be improved, and the steel forming process can be completed. At this time, the microstructure of the steel is troostite.

[0029] The fourth technical solution of the present invention is to provide a post-forming heat treatment process for a 1300MPa grade thick steel plate for pressure-bearing equipment; in order to ensure the ultra-high strength and excellent plastic toughness of the steel for pressure-bearing equipment, it is necessary to further adjust the size and type of the second phase particles in the steel, that is, secondary hardening heat treatment, the process is a heating temperature of 400-430°C, a net heat preservation of 2.0-4.0h, at which time a stable (10-30)nm level (Fe, Mn, Cr, Mo) is precipitated in the steel 23 C 6 、Mo 2 C second phase particles and borides account for 18% to 23% of the volume. They interact with the high-density dislocations of the troostite to improve the strength and plasticity of the matrix. The mechanical properties of the steel after forming and heat treatment are 950MPa≤R p0.2 ≤1100MPa, 1300MPa≤Rm≤1430MPa, elongation A≥19%; at 400℃, 560MPa≤Rp 0.2 ≤630MPa; Impact energy KV at 0℃ 2 ≥120J; ensure the use requirements of high-strength pressure-bearing equipment.

[0030] The beneficial effects of the present invention are:

[0031] (1) By adding Cr, Mo, Ni, and B alloy elements in combination with C, Si, and Mn strengthening elements, while strictly controlling the content of harmful elements P and S, and combining the manufacturing process, the steel plate of the present invention obtains a high-density troostite structure.

[0032] (2) The mechanical properties of the steel plate for pressure equipment obtained through a unique production process are 930MPa≤R at room temperature. p0.2 ≤1080MPa、1300MPa≤R m ≤1430MPa, impact energy KV at 0℃ 2 ≥100J.

[0033] (3) The steel plate of the present invention obtains a high-density troostite structure after forming and secondary hardening heat treatment, and a large amount of (10-30) nm-level (Fe, Mn, Cr, Mo) is dispersed and precipitated in the steel. 23 C 6 、Mo 2 C second phase particles and borides account for 18% to 23% of the structure, ensuring that the steel plate still has 1300MPa strength and good plasticity after forming.

[0034] (4) The mechanical properties of the steel plate for pressure equipment obtained through a unique production process are 950MPa≤R at room temperature. p0.2 ≤1100MPa、1300MPa≤R m≤1430MPa; at 400℃, 560MPa≤R p0.2 ≤630MPa; Impact energy KV at 0℃ 2 ≥120J.

[0035] (5) The present invention obtains a 1300MPa grade high-strength steel plate for pressure-bearing equipment with a thickness specification of (40 to 80) mm. DETAILED DESCRIPTION

[0036] The present invention will be further described below by way of examples.

[0037] The embodiment of the present invention performs smelting, continuous casting, controlled rolling, controlled cooling, tempering, forming and heat treatment according to the component ratio of the technical solution.

[0038] A method for manufacturing a thick steel plate for 1300MPa-level pressure-bearing equipment, comprising smelting, continuous casting, heating, rolling and tempering;

[0039] Heating: The heating temperature is controlled at 1180-1230°C, and the total heating time is 4.0-6.0h;

[0040] Controlled rolling: The rolling adopts a two-stage controlled rolling method. The end rolling temperature of the recrystallization zone is ≥1000℃, and the total deformation rate is ≥50%; the starting rolling temperature of the non-recrystallization zone is 870~930℃, the final rolling temperature is 830~870℃, and the total deformation rate is ≥55%;

[0041] Controlled cooling: cooling temperature 780-820℃, cooling rate 30-55℃ / S, red-return temperature 450-500℃;

[0042] Tempering: The tempering temperature is 650-700°C, and the insulation time is 2.0-4.0min / mm.

[0043] Further; smelting: molten steel smelting is carried out in a converter, using high-quality scrap steel and molten iron as raw materials, the molten iron content is controlled at 75% to 85%, dephosphorization and decarburization are smelted separately in a converter, wherein the dephosphorization oxygen blowing is controlled at 7 to 10 minutes, and the decarburization oxygen blowing is controlled at 8 to 12 minutes, and finally the phosphorus mass fraction is reduced to less than 0.006%; deep desulfurization treatment is carried out in an LF refining furnace, and the sulfur content is controlled below 0.002%; degassing is completed in a VD furnace, the net cycle time is 10 to 15 minutes, and the calming time before pouring is 3 to 5 minutes.

[0044] Further; continuous casting: superheat degree is 20-30℃, and the casting speed is 1.0-1.4m / min. The billet is stacked and slowly cooled down after it comes off the line, and the stacking slow cooling time is 24-36h, and the billet is unstacked below 400℃.

[0045] A forming process for thick steel for 1300MPa-level pressure-bearing equipment. During the forming process, the heating temperature is 930-960°C, the net insulation time is 1.0-2.0min / mm, and after being taken out of the furnace, it enters a salt water bath and is quickly cooled to room temperature at a cooling rate of 35-55°C / S.

[0046] Further; a short-time tempering heat treatment is carried out after the salt water bath, the short-time tempering heat treatment temperature is 370-400°C, the net holding time is 0.5-1.0h, and the microstructure of the steel after the short-time tempering heat treatment is troostite.

[0047] A post-forming heat treatment process for thick steel for 1300MPa-level pressure-bearing equipment, wherein the post-forming heat treatment is a secondary hardening heat treatment, the matrix process is a heating temperature of 400-430°C, and a net insulation time of 2.0-4.0h.

[0048] Further; it is characterized in that: after the secondary hardening heat treatment, the steel precipitates (10 to 30) nm level (Fe, Mn, Cr, Mo) 23 C 6 、Mo 2 The volume fraction of C second phase particles and borides is 18% to 23%.

[0049] Furthermore, after secondary hardening heat treatment, the mechanical properties of the steel are 950MPa≤R p0.2 ≤1100MPa、1300MPa≤R m ≤1430MPa; at 400℃, 560MPa≤R p0.2 ≤630MPa, impact energy KV at 0℃ 2 ≥120J.

[0050] The composition of the steel of the present invention is shown in Table 1. The main process parameters of the steel of the present invention are shown in Table 2. The main process parameters of the steel of the present invention during forming and heat treatment are shown in Table 3. The mechanical properties and microstructure of the steel of the present invention are shown in Table 4. The mechanical properties and microstructure of the steel of the present invention after forming and heat treatment are shown in Table 5.

[0051] Table 1 Composition of steel according to the present invention

[0052] Example C Si Mn P S Cr Mo B Alt 1 0.22 0.12 0.60 0.006 0.001 1.45 0.43 0.003 0.039 2 0.20 0.18 0.64 0.006 0.002 1.87 0.50 0.002 0.022 3 0.19 0.30 0.70 0.008 0.003 1.68 0.58 0.004 0.033 4 0.19 0.18 0.52 0.010 0.001 2.00 0.40 0.001 0.028 5 0.20 0.25 0.45 0.005 0.002 1.65 0.49 0.005 0.045 6 0.20 0.35 0.70 0.009 0.001 1.40 0.60 0.003 0.031 7 0.23 0.40 0.50 0.006 0.001 1.80 0.56 0.002 0.028 8 0.21 0.24 0.40 0.007 0.002 1.95 0.57 0.004 0.020 9 0.23 0.15 0.57 0.009 0.003 1.75 0.44 0.001 0.023 10 0.22 0.10 0.65 0.006 0.001 1.50 0.47 0.005 0.040

[0053] Table 2 Main process parameters of steel rolling in the embodiment of the present invention

[0054]

[0055] Table 3 Main process parameters of steel forming and heat treatment in the embodiment of the present invention

[0056]

[0057] Table 4 Mechanical properties and microstructure of steel in the embodiment of the present invention

[0058] Example Sampling location <![CDATA[R p0.2 / MPa]]> <![CDATA[R m / MPa]]> A / ％ <![CDATA[(0℃)KV 2 / J]]> Microstructure 1 T / 4 986 1325 19.0 118 Sorbite 2 T / 4 1023 1340 19.0 100 Sorbite 3 T / 4 1050 1352 19.5 110 Sorbite 4 T / 4 1000 1300 21.0 122 Sorbite 5 T / 4 995 1385 19.5 100 Sorbite 6 T / 4 1017 1408 19.0 109 Sorbite 7 T / 4 1060 1420 19.0 106 Sorbite 8 T / 4 991 1361 19.0 115 Sorbite 9 T / 4 933 1302 20.5 122 Sorbite 10 T / 4 1012 1374 19.0 101 Sorbite

[0059] Table 5 Mechanical properties and microstructure of steel plates after forming and heat treatment according to the present invention

[0060]

[0061] According to the above results, the 1300MPa grade steel plate for pressure-bearing equipment produced by the present invention has extremely low P and S harmful element contents, and its mechanical properties are 800MPa≤R p0.2 ≤930MPa、1100MPa≤R m ≤1200MPa, elongation A≥19%; impact energy KV at 0℃ 2 ≥100J. The mechanical properties of steel after forming and heat treatment are 950MPa≤R p0.2 ≤1100MPa, 1300MPa≤Rm≤1430MPa, elongation A≥19%; at 400℃, 560MPa≤Rp 0.2 ≤630MPa; Impact energy KV at 0℃ 2 ≥120J.

[0062] In order to describe the present invention, the present invention is appropriately and fully illustrated by the examples in the above. The above implementation modes are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made should be included in the protection scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. A 1300MPa grade thick steel plate for pressure-bearing equipment, characterized in that: The composition of the steel plate is as follows by weight percentage: C 0.19%~0.23%, Si 0.10%~0.40%, Mn 0.40%~0.70%, P ≤0.010%, S ≤0.003%, Cr 1.40%~2.0%, Mo 0.40%~0.60%, B 0.001%~0.005%, Alt 0.015%~0.045%, and the balance is Fe and unavoidable inclusions; The manufacturing method of the 1300MPa grade thick steel plate for pressure-bearing equipment comprises smelting, continuous casting, heating, controlled rolling, controlled cooling and tempering; Heating: The heating temperature is controlled at 1180~1230℃, and the total heating time is 4.0~6.0h; Controlled rolling: The rolling adopts a two-stage controlled rolling method. The end rolling temperature of the recrystallization zone is ≥1000℃, and the total deformation rate is ≥50%; the starting rolling temperature of the non-recrystallization zone is 870~930℃, the final rolling temperature is 830~870℃, and the total deformation rate is ≥55%; Controlled cooling: cooling temperature 780~820℃, cooling rate 30~55℃ / s, red-return temperature 450~500℃; Tempering: The tempering temperature is 650~700℃, and the net holding time is 2.0~4.0 min / mm.

2. The 1300MPa grade thick steel plate for pressure-bearing equipment according to claim 1, characterized in that: The thickness of the thick steel plate for pressure equipment is 40~80mm; the mechanical properties of the thick steel plate for pressure equipment are 930MPa≤ R p0.2 ≤1080MPa、1300MPa≤ R m ≤1430MPa; impact energy at 0℃ KV 2≥100J.

3. The 1300MPa grade thick steel plate for pressure-bearing equipment according to claim 1, characterized in that: Smelting: The smelting of molten steel is carried out in a converter, using high-quality scrap steel and molten iron as raw materials. The molten iron content is controlled at 75%~85%. Dephosphorization and decarburization are smelted separately in a converter, with oxygen blowing for dephosphorization controlled at 7~10min and oxygen blowing for decarburization controlled at 8~12min, ultimately reducing the phosphorus mass fraction to less than 0.006%. Deep desulfurization is carried out in the LF refining furnace, and the sulfur content is controlled below 0.002%. Degassing is completed in a VD furnace, with a net cycle time of 10~15min and a calming time of 3~5min before pouring.

4. The 1300MPa grade thick steel plate for pressure-bearing equipment according to claim 1, characterized in that: Continuous casting: superheat is 20~30℃, and the casting rate during casting is 1.0~1.4m / min. The billets are stacked and slowly cooled after coming off the line. The stacking slow cooling time is 24~36h, and the billets are unstacking below 400℃.

5. A forming process of a 1300MPa grade thick steel plate for pressure-bearing equipment using any one of claims 1 to 4, characterized in that: During the forming process, the heating temperature is 930~960℃, the net holding time is 1.0~2.0min / mm, and after being taken out of the furnace, it enters the salt water bath and is rapidly cooled to room temperature at a cooling rate of 35~55℃ / s; after the salt water bath, short-time tempering heat treatment is carried out, the short-time tempering heat treatment temperature is 370~400℃, the net holding time is 0.5~1.0h, and the microstructure of the steel after short-time tempering heat treatment is troostite.

6. The molding process according to claim 5, characterized in that: After the molding process, a secondary hardening heat treatment is performed, and the specific process is a heating temperature of 400-430° C. and a net insulation time of 2.0-4.0 h.

7. The molding process according to claim 6, characterized in that: After the secondary hardening heat treatment, 10~30nm level (Fe, Mn, Cr, Mo) are precipitated in the steel 23 The volume fraction of C6, Mo2C second phase particles and borides is 18%~23%.

8. The molding process according to claim 6, characterized in that: After secondary hardening heat treatment, the mechanical properties of the steel are 950MPa≤ R p0.2 ≤1100MPa、1300MPa≤ R m ≤1430MPa; at 400℃, 560MPa≤ R p0.2 ≤630MPa; impact energy at 0℃ KV 2≥120J.

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