CN114892085B - Wide and thick steel plate for advanced nuclear power unit positioning and manufacturing method thereof - Google Patents

Abstract

The invention provides a wide and thick steel plate for positioning of advanced nuclear power units and a manufacturing method thereof. The composition of the steel plate is as follows by weight percentage: C 0.13%-0.16%, Si 0.20%-0.30%, Mn 0.30%-0.60%, P ≤0.006%, S≤0.002%, Cr 2.55%～2.85%, Mo 0.80%～1.20%, Ni 1.20%～1.50%, Nb 0.04%～0.08%, V 0.10%～0.20%, Ti≤0.03%, Alt ≤0.02%, Ca 0.001%～0.004%, N 0.01%～0.03%, Sn≤0.001%, H≤0.0001%, O≤0.0020%, the balance is Fe and unavoidable inclusions, high temperature tempering embrittlement resistance coefficient J =(Si+Mn)×(P+Sn)×10 ⁴ ≤50; the manufacturing method includes smelting, continuous casting, electroslag remelting, controlled rolling, controlled cooling, and heat treatment; the specifications of the steel plate of the present invention are (100-130 )mm×(4500～5100)mm×Lmm, the performance meets the manufacturing and use requirements of the fourth-generation nuclear power plant positioning board.

Description

Wide and thick steel plate for positioning of advanced nuclear power unit and manufacturing method thereof

technical field

The invention belongs to the field of metal materials, and in particular relates to a wide and thick steel plate for positioning advanced nuclear power units and a manufacturing method thereof.

Background technique

As one of the clean and efficient energy sources in the world, nuclear energy has been utilized by humans for more than 70 years. Since the beginning of the 21st century, the contradiction between frequent human activities and global economic development, energy shortage and extreme climate has become increasingly prominent. Under such a background of global integration, the advantages of nuclear energy have become more prominent. Therefore, the peaceful development of more advanced nuclear energy is still the trend of the times. At present, after the development of the first-generation experimental prototype reactor, the second-generation pressurized water reactor, and the third-generation advanced light-water reactor, nuclear energy technology includes sodium liquid-cooled fast reactor, air-cooled fast reactor, and lead-liquid cooled fast reactor. , Ultra-high temperature gas-cooled reactor, molten salt reactor and supercritical water-cooled reactor and other fourth-generation advanced nuclear technologies have been proposed by global nuclear energy experts and become the development direction of future nuclear power technology.

The main characteristics of fourth-generation nuclear energy technology are better safety, better economy, less nuclear waste, and effective prevention of nuclear proliferation. Therefore, very high requirements are put forward for nuclear technology and nuclear equipment. For example, the structural steel used for positioning nuclear grade parts is not only exposed to high temperature and hydrogen environment, but also subjected to strong fast neutron irradiation, matrix embrittlement and hydrogen corrosion caused by water decomposition. The risk is several times that of previous generations of nuclear power technology, and the size of the equipment is large, which poses a huge challenge to the development of large-scale steel. Therefore, the development of key nuclear equipment and key nuclear materials that meet the needs of the fourth-generation advanced nuclear power plants has become the core problem that the world's nuclear energy powers urgently need to solve.

The published invention patent "A Manufacturing Method for Quenching and Heat Treatment of Ultra-Wide and Extra-Thick Steel Containment Steel for Nuclear Power Plants" (publication number CN201811165268.5), from the published patent information, the maximum thickness of the patent is 101mm, and the maximum width is 4600mm , cannot cover the thickness and width specifications required by the fourth-generation nuclear power, and the heat treatment method only introduces the quenching process.

Invention patent "A method for producing ultra-thin and ultra-wide steel for nuclear power with a wide and thick plate rolling mill" (publication number CN202010240194.8), from the published patent information, the maximum thickness of this patent is 6mm, and the maximum width is 4700mm. It is used for the manufacture of nuclear power containment and cannot meet the requirements of the core positioning plate.

Invention patent "A wide and thick steel plate for nuclear power and its manufacturing method" (publication number CN201910725047.7), from the disclosed composition, production method and beneficial effects, although this patent can develop wide and thick steel for nuclear power, the embodiment The maximum thickness is 101mm and the maximum width is 4300mm. The mechanical properties involved can only guarantee the use requirements under the working environment temperature of 150°C. There is no explanation or guarantee for the higher use temperature, and it is clearly stated that the patent is used for the third-generation nuclear power containment steel Manufacture of SA738Gr.B.

The above-mentioned disclosed invention patents mainly relate to the metal materials required by the third-generation nuclear power equipment. Compared with the key materials required by the fourth-generation nuclear power technology, they are characterized by relatively low high-temperature service temperature, no hydrogen in the contact environment, and short post-weld heat treatment time. , The mechanical performance index of the material is relatively single. The steel used to manufacture positioning plates requires a high degree of homogenization, high temperature fracture toughness, low NDT temperature, and excellent resistance to hydrogen-induced cracking. In addition, in order to improve the operation safety of large-scale units, large-scale plates are required to manufacture key equipment through a welding-free one-time forming process, so the design specifications of the plates have reached (100-130)mm×(4500-5100)mm×Lmm, and at the same time require The high-temperature performance after 700°C×20h post-weld heat treatment is the same as the performance state, and there is no public report on the invention of the materials required by the above-mentioned stringent technical indicators.

Contents of the invention

The object of the present invention is to overcome the above-mentioned problems and deficiencies and provide a steel plate with a specification of L×(4500～5100)mm×(100～130)mm, which can withstand high temperature at 370°C and has a steel plate at 370°C after 700°C×20h post-weld heat treatment. High-temperature strength, high-temperature toughness, low-temperature drop weight and hydrogen-induced cracking resistance advanced wide-thick steel plate for positioning of nuclear power units and its manufacturing method meet the requirements for the manufacture and use of positioning plates for fourth-generation nuclear power plants.

The purpose of the invention is achieved in this way:

The present invention aims to adopt brand-new chemical composition design and suitable production process, on the basis of medium and low C, Si, Mn components, compoundly add Cr, Mo, Ni, Nb, V, Ti and N alloy elements, and strictly control harmful elements P, S, Sn and gas O, H content, combined with unique smelting, rolling and heat treatment production processes, develop high-performance nuclear energy key materials that meet the needs of key equipment in fourth-generation nuclear power plants, and solve the problem of "equal meters" for my country's advanced nuclear power units the embarrassing situation.

A wide and thick steel plate for the positioning of advanced nuclear power units, the composition of the steel plate is as follows by weight percentage: C0.13%-0.16%, Si 0.20%-0.30%, Mn 0.30%-0.60%, P≤0.006%, S≤0.002 %, Cr2.55%～2.85%, Mo 0.80%～1.20%, Ni 1.20%～1.50%, Nb 0.04%～0.08%, V0.10%～0.20%, Ti≤0.03%, Alt≤0.02%, Ca 0.001%～0.004%, N 0.01%～0.03%, Sn≤0.001%, H≤0.0001%, O≤0.0020%, the balance is Fe and unavoidable inclusions, high temperature tempering embrittlement resistance J=(Si+Mn )×(P+Sn)×10 ⁴ ≤50.

In the steel sheet, Mo/Si is 3-5, and (Cr+Mn)/Mo is 2.5-4.0.

The microstructure of the steel plate is a composite structure of undissolved ferrite and tempered bainite, wherein the bainite structure contains a large amount of dispersed and precipitated (Fe, Mn, Cr, Mo) ₂₃ C ₆ alloy carbides , The volume percentage of undissolved ferrite is 10% to 15%.

The mechanical properties of the steel plate at room temperature are 497MPa≤R _eL ≤512MPa, 605MPa≤R _m ≤620MPa, 460MPa≤R _m ≤480MPa _{at 370°C;} , KV _2(80°C) ≥400J, T _NDT ≤-40°C, CSR of HIC (A solution) is 0%, 264MPa·m ^1/2 ≤KIC≤269MPa·m ^1/2 ; the steel plate size is ( 100～130)mm×(4500～5100)mm×Lmm.

The composition design reason of the present invention is as follows:

C in the present invention mainly solid-solution state C and compound state C guarantee the heat treatment of steel and the high-temperature strength performance of post-weld heat treatment state, the thickness specification of the present invention is bigger, therefore the lower limit of setting carbon content is 0.13%, but Excessive carbon content will affect the weldability of the steel, so the present invention sets the C content range to 0.13%-0.16%.

Si is a good reducing agent and deoxidizing agent in the steelmaking process, especially when used in combination with Alt, it can significantly increase the deoxidizing ability of Alt. Si forms a dense, anti-oxidation SiO ₂ protective film on the surface at high temperatures. In addition, Si and Mo combine to form MoSi ₂ , an intermetallic compound. The atomic combination in its crystal structure presents the coexistence of metal bonds and covalent bonds. It has excellent high-temperature oxidation resistance, so the Mo/Si ratio in the present invention is limited to 3-5, so as to ensure that a certain amount of MoSi ₂ structure is formed inside the steel plate. However, in the temper embrittlement temperature range of 350-550°C, too high silicon content will lead to an increase in the temper embrittlement sensitivity of the steel, so it is not suitable to add too much silicon in the present invention, so the present invention sets the Si content range 0.20% to 0.30%.

Mn In the present invention, because the addition of deoxidizers such as Si and Alt is less, the addition of Mn makes up for the effect of insufficient deoxidation. In addition, Mn, as an alloy element with strong solid solution strengthening ability, improves the matrix strength, but Mn improves the temper brittleness. The sensitive elements of the present invention need to be strictly controlled, so the present invention sets the Mn content range as 0.30% to 0.60%.

S and P, as harmful elements in steel, must be strictly controlled in order to ensure the purity of steel, J coefficient and fracture toughness, so they are limited to S≤0.002%, P≤0.006%.

As a strong carbide-forming element, Cr combines with Fe, Mn, and Mo in the steel to form a stable M ₂₃ C ₆ alloy carbide, which ensures the high-temperature performance of the long-term post-weld heat treatment state, and at the same time exerts the high-temperature resistance of Cr. For oxidation, the present invention sets the Cr content range at 2.55% to 2.85%.

Mo improves the hardenability of steel and ensures the matrix strength of steel. At the same time, Mo is a strong carbide forming element, and forms a stable Mo ₂ C thermal strengthening phase with carbon elements, which plays a role in high temperature strengthening. In addition, this patent adds more Cr element and certain Mn element, they are very easy to co-segregate with P, Sn and other impurity elements at the grain boundary, causing high temperature temper embrittlement and affecting the high temperature performance of steel. The role of Mo is just the opposite, which promotes the precipitation of P in the grain to prevent grain boundary segregation. Therefore, the present invention limits (Cr+Mn)/Mo to 2.5-4.0, so as to ensure the structure and performance of the positioning plate steel when it works at 370°C For stability, the present invention sets the Mo content range at 0.80% to 1.20%.

Ni In the present invention, the Ni element mainly improves the hydrogen corrosion resistance and plastic toughness of steel, reduces the ferrite non-ductility transition temperature, and prevents the increase of the non-ductility transition temperature caused by nuclear irradiation, but if the Ni content is too high, it will The radiation resistance of the material is reduced, so the present invention sets the Ni content in the range of 1.20% to 1.50%.

Nb plays the role of refining the grains in the present invention, improving the strength, toughness and hydrogen-induced cracking resistance of the steel through grain refinement, and also making the steel have good hydrogen resistance by forming carbides to consume carbon . Therefore, the Nb content is limited to 0.04% to 0.08%.

V is added in a large amount in the present invention, and one of the main functions is that the carbon and nitrogen complexes formed with C and N elements during the long-term high-temperature post-welding tempering process are very stable, ensuring the high temperature of the high-temperature post-weld heat treatment state. strength; secondly, V fixes C in vanadium-carbon compounds, which greatly improves the hydrogen resistance stability of steel under high temperature and high pressure; in addition, the addition of V alloy effectively inhibits the segregation of Cr and Mn elements at grain boundaries induced by irradiation, so The V content is limited to 0.10% to 0.20%.

Ti is one of the strong ferrite-forming elements and strongly increases the A1 and A3 temperatures of the steel. Titanium can improve plasticity and toughness in steel. Since titanium fixes carbon and nitrogen and forms carbon and titanium nitride, the strength of steel is improved. After normalizing heat treatment, the grains are refined, and the precipitation and formation of carbides can significantly improve the plasticity and impact toughness of the steel, so the Ti content is limited to ≤0.03%.

Sn is a residual element in steel, which not only affects the purity of steel, but also as an important element affecting the J coefficient of temper brittleness, it must be strictly controlled, so the Sn content is limited to ≤0.001%.

Ca spheroidization treatment of Ca inclusions in the present invention, MnS inclusions become CaS or composite inclusions containing CaS, making Al ₂ O ₃ inclusions into calcium aluminate oxide inclusions, which are spherical and dispersed Distribution, basically no deformation at the rolling temperature of the steel, and it is still spherical after rolling, so Ca treatment can reduce the hydrogen-induced cracking susceptibility of the steel. However, if Ca is added too much, the size of Ca(O, S) will be too large, and the brittleness will also increase, which can become the starting point of fracture cracks, which will reduce the low temperature toughness, ductility and weldability of steel, and reduce the purity of steel. The invention sets the Ca content range as 0.001% to 0.004%.

Alt In the present invention, the Alt element is embodied as a participating or a small amount of added element to play the role of a deoxidizer. The main purpose of not adding Alt is to ensure the purity of the steel, so the Alt content is limited to ≤0.02%.

N forms nitrides with Nb, V and other elements, precipitates at the grain boundaries, pins the grain boundaries to refine the grains, and plays a role in improving the high-temperature strength of the grain boundaries, so the N content is limited to 0.01% to 0.03%.

The existence of H and O as harmful gases will cause many defects, such as H causes defects such as "white spots" or "hydrogen embrittlement" in steel, which seriously affects the service life of materials and equipment safety; O forms non-metallic oxidation with Al and Si elements substances, which affect the purity of steel and the mechanical properties of materials, must be strictly controlled, so the O content is limited to ≤0.0020%, and the H content is limited to ≤0.0001%.

The second technical solution of the present invention is to provide a method for manufacturing wide and thick steel plates for positioning of advanced nuclear power units, including smelting, continuous casting, electroslag remelting, controlled rolling, and heat treatment;

(1) Smelting process: including converter smelting, LF furnace refining, RH refining;

In the process of converter smelting, in order to effectively reduce the content of harmful element P, dephosphorization and decarburization are smelted separately by converter, in which dephosphorization and oxygen blowing are controlled at 7-10 minutes, and decarburization and oxygen blowing are controlled at 8-12 minutes;

High-quality steel scrap and molten iron are preferably used as raw materials, and the content of molten iron is controlled at 70% to 80%;

Deep desulfurization treatment is carried out during the LF refining process, and CaSi wire is fed into the steel for calcium treatment at the same time. The wire feeding speed is 200-350m/min, and the wire feeding depth is 1.0-2.0m below the slag layer. This treatment changes non-metallic inclusions shape, forming fine CaS or calcium aluminate spherical inclusions, increasing the isometric ratio of the billet and purifying the steel, improving the purity, and improving the hydrogen resistance of the steel. The thickness of the generated slag layer is 60-90mm, ensuring that the inclusions Fully floated;

The degassing in the furnace is completed during the RH refining process, the net cycle time is 10-15 minutes, and the calming time before pouring is 3-5 minutes.

(2) Continuous casting: the degree of superheat is 20-30°C; preferably, the cast slabs are rolled off the assembly line and put into stacks for slow cooling, the stacking slow cooling time is 48-72 hours, and the stacks are unstacked below 300°C to prevent cracks inside the cast slabs due to rapid cooling.

(3) Electroslag remelting: In order to further improve the purity of steel, eliminate internal defects such as segregation and porosity, reduce non-metallic inclusions, and homogenize the as-cast structure, the addition of electroslag remelting process is very important for high temperature performance and hydrogen induced resistance. Crackability is critical. The invention uses electroslag steel ingots with a thickness of 500 to 700 mm to ensure a sufficient compression ratio to roll finished steel plates of 100 mm and above. After the electroslag ingots are demoulded, the stacking and slow cooling time is 48 to 72 hours, and the destacking is air-cooled below 300 ° C.

(4) Controlled rolling: controlled rolling is divided into two stages;

The first stage: heating + billet rolling;

Due to the ultra-large thickness of the electroslag steel ingot, the rolling of the final specification steel plate cannot be completed in one rolling, and the billet opening process is required first. The specific process is to control the heating temperature at 1180-1250°C, and the total heating time is 24-30h to ensure that the inside of the electroslag steel ingot Heating is sufficient and uniform to prevent black steel from rolling.

The longitudinal-horizontal rolling strategy is adopted when the ingot is billeted. The longitudinal rolling stage is less than no more than 4 passes, the steel is turned 90°, and the width is rolled. The horizontal rolling stage is less than 3 passes. The total number of blanking passes is not more than 7 passes. The reduction in a single pass is not less than 40mm, and the thickness of the billet after billeting is 300-350mm, ensuring that the whole process is rolled under a large reduction, and the core structure of the steel ingot is fully crushed.

Preferably, in order to ensure the internal quality of the steel plate, the steel slabs are stacked off-line and cooled slowly, the slow cooling temperature is ≥ 400°C, and the slow cooling time is 48-72h. After unstacking, the surface of the billet is cleaned to ensure the surface quality of the rolled steel plate.

The second stage: heating + rolling;

By controlling the heating process of the steel slab, it is ensured that the alloy elements are fully dissolved, and the growth of the original austenite grains is effectively inhibited. The heating temperature is controlled at 1180-1250°C, the heating is 6-8 hours, and the soaking time is 1.0-2.0 hours. Rolling is completed in the high-temperature recrystallization zone, and the horizontal-longitudinal rolling strategy is adopted. During horizontal rolling, the target width of direct rolling is more than 4800mm, the steel is turned at 90°, and the longitudinal rolling reaches the target thickness to ensure the final shape of the steel plate, and the cumulative reduction rate reaches More than 60%, rolled until the specification of the steel plate is length×width×height is L×(4500～5100)mm×(100～130)mm, where L is the length of the steel plate.

(5) Heat treatment: In order to obtain the microstructure that meets the stringent performance requirements of the present invention, it needs to be completed through the final heat treatment process. The present invention adopts multiple heat treatment processes of high temperature normalizing + sub-temperature quenching + high temperature tempering;

The A _C3 temperature of the steel grade of the present invention is approximately 850°C, the high-temperature normalizing temperature is designed according to A _C3 + (100-150)°C, that is, 950°C-1000°C, the holding time is 0.5min/mm-1.0min/mm, air cooling to room temperature. This process eliminates the grain difference and structure segregation produced in the rolling process due to the oversize of the rolled piece, and ensures the homogenization and hydrogen-induced cracking resistance of the product of the present invention;

The sub-temperature quenching temperature is 800-850°C, and the holding time is ^0.5-1.5min /mm. The following process parameters are obtained by adjusting the water volume and water pressure of the quenching unit. : (1.5～2.5), swing watering, roll speed 0.5～1.0m/s, reddening temperature 350～450℃, then cool to room temperature with air, heat through the two-phase zone, the undissolved ferrite is more likely to refine the grain grains, to obtain the full-thickness undissolved ferrite and lower bainite dual-phase structure of the steel plate.

In addition, in order to obtain the excellent processability and use performance of the product of the present invention, the upper limit of the heat-treated tensile strength of the material calculated according to the design allowable stress shall not exceed 620MPa, and at the same time, the tensile strength of the post-weld heat-treated state at 370°C shall not be less than 450MPa Therefore, it is necessary to further regulate the structure and performance through precise tempering heat treatment. The present invention designs a tempering temperature of 710-730°C, and a holding time of 60min+1.0-2.0min/mm×T, where T is the thickness of the steel plate, and the unit is mm , under this process, the lower bainite fully recovers and softens, and the alloy carbides with the (Fe, Mn, Cr, Mo) ₂₃ C ₆ structure do not aggregate and grow, and are dispersed in the bainitic ferrite matrix or grains in a highly spheroidized form. At the boundary, this structure is characterized by strong high temperature stability, no essential changes after post-weld heat treatment at 700°C×20h, which ensures the comprehensive performance after long-term welding, especially high-temperature strength and toughness, fracture toughness and Low temperature drop weight performance.

The beneficial effects of the present invention are:

(1) On the basis of medium and low C, Si, Mn components, strictly control the content of harmful elements P, S, Sn and gas O, H, control the tempering embrittlement coefficient below 50, and add Cr, Mo, Ni, The combined manufacturing process of Nb, V, Ti and N alloy elements obtains a composite structure containing 10-15% undissolved ferrite and tempered bainite, in which the bainite structure contains a large amount of dispersed precipitated (Fe, Mn, Cr , Mo) ₂₃ C ₆ structure of alloy carbide, to ensure the comprehensive performance requirements of large size positioning plate.

(2) The mechanical properties of wide and thick steel plates for positioning of advanced nuclear power units obtained through a unique production process are 497MPa≤R _eL ≤512MPa, 605MPa≤R _m ≤620MPa, 460MPa≤R _m ≤480MPa at 370°C in the delivery state ;700℃×20h post-weld heat treatment state 450MPa≤R _m(370℃) ≤470Mpa, KV _2(80℃) ≥400J, T _NDT ≤-40℃, CSR of HIC (A solution) is 0%, 264MPa· m ^1/2 ≤K _IC ≤269MPa·m ^1/2 , obtained a (100～130)mm×(4500～5100)mm×Lmm large-sized positioning plate, which filled the gap in terms of excellent comprehensive performance and size specifications This type of product is blank.

Detailed ways

Below by embodiment the present invention will be further described. In the embodiment of the present invention, smelting, continuous casting, electroslag remelting, heating, controlled rolling, and heat treatment are carried out according to the component ratio of the technical solution.

(1) Controlled rolling: controlled rolling is divided into two stages;

The first stage: heating + billet rolling;

Heating is carried out before billet rolling, the heating temperature is controlled at 1180-1250°C, and the total heating time is 24-30 hours;

The billet rolling of the ingot adopts the longitudinal-horizontal rolling strategy. The rolling passes in the longitudinal rolling stage are less than no more than 4 passes, the steel is turned at 90°, and the rolling is extended. The rolling passes in the horizontal rolling stage are less than 3 passes. The total number of billets is not more than 7, the single-pass reduction is not less than 40mm, and the billet after billet opening is 300-350mm;

The second stage: heating + rolling;

The billet is heated before rolling in the second stage. The heating temperature of the billet is controlled at 1180-1250°C for 6-8 hours, and the soaking time is 1.0-2.0 hours;

The second stage of rolling is completed in the high-temperature recrystallization zone. The horizontal-longitudinal rolling strategy is adopted. During the horizontal rolling, the target width of direct rolling is more than 4800mm, the steel is turned at 90°, the longitudinal rolling reaches the target thickness, and the cumulative reduction rate reaches more than 60%. , rolled to specifications (100～130)mm×(4500～5100)mm×Lmm;

(2) Heat treatment: Multiple heat treatment processes of high temperature normalizing + sub-temperature quenching + high temperature tempering are adopted;

High temperature normalizing: high temperature normalizing temperature is A _C3 + (100 ~ 150) ℃, holding time is 0.5min/mm ~ 1.0min/mm, air cooling to room temperature;

Sub-temperature quenching: the sub-temperature quenching temperature is 800-850°C, the holding time is 0.5-1.5min/mm, and then water-cooled, and the red temperature is 350-450°C, and then air-cooled to room temperature;

High-temperature tempering: Tempering temperature is 710-730°C, holding time is 60min+1.0-2.0min/mm×T, T is the thickness of the steel plate, and the unit is mm.

Further; after the billet rolling in the first stage in the step (1), the steel billets are off-line and stacked for slow cooling, the slow cooling temperature is ≥ 400°C, and the slow cooling time is 48-72h.

Further; the high temperature tempering temperature in the step (2) is 950°C to 1000°C.

Further; The water-cooling process parameter in the sub-temperature quenching process in the described step (2) is:

The water volume of the quenching unit is 120-150m ³ /min, the water pressure is 4-7bar, the ratio of water to water is 1:(1.5-2.5), swing watering, and the roller speed is 0.5-1.0m/s.

Further; the smelting process includes converter smelting, LF furnace refining, RH refining;

In the process of converter smelting, dephosphorization and decarburization are smelted separately by converter, in which dephosphorization and oxygen blowing are controlled at 7-10 minutes, and decarburization and oxygen blowing are controlled at 8-12 minutes;

Deep desulfurization treatment is carried out during the LF refining process, and CaSi wire is fed into the steel for calcium treatment at the same time, the wire feeding speed is 200-350m/min, the wire feeding depth is 1.0-2.0m below the slag layer, and the thickness of the generated slag layer is 60~ 90mm, to ensure that inclusions fully float up;

The degassing in the furnace is completed during the RH refining process, the net cycle time is 10-15 minutes, and the calming time before pouring is 3-5 minutes.

Further; steel scrap and molten iron are used as raw materials in the converter smelting process, and the content of molten iron is controlled at 70% to 80%.

Further; the continuous casting: the degree of superheat is 20-30°C, the billets are rolled off the assembly line and put into stacking for slow cooling, the stacking slow cooling time is 48-72h, and the stacking is destacked below 300°C.

Further; the electroslag remelting: the thickness and section of the electroslag remelting steel ingot is 500-700mm, the stacking and slow cooling time of the electroslag ingot after demoulding is 48-72h, and the destacking is air-cooled below 300°C.

The composition of the steel of the embodiment of the present invention is shown in Table 1. The main technological parameters of the smelting of the steel of the embodiment of the present invention are shown in Table 2. The rolling process parameters of the steel in the embodiment of the present invention are shown in Table 3. The heat treatment process parameters of the steel in the embodiment of the present invention are shown in Table 4. Table 5 shows the final effect of the steel microstructure and properties of the embodiments of the present invention. See Table 6 for the HIC test results (solution A) of the steel examples of the present invention for their resistance to hydrogen-induced cracking. The results of the fracture toughness test of the embodiments of the present invention are shown in Table 7.

Table 1 Composition (wt, %) of the embodiment steel of the present invention

Table 2 The smelting process parameters of the embodiment steel of the present invention

The rolling process parameter of table 3 embodiment steel of the present invention

Note: L is the length of the steel plate.

The heat treatment process parameter of table 4 embodiment steel of the present invention

Table 5 steel structure and performance of the embodiment of the present invention

Table 6 embodiment anti-hydrogen-induced cracking HIC test results (A solution)

Table 7 embodiment fracture toughness test result

According to the above results, it can be concluded that the advanced nuclear power unit positioning steel plate provided by the present invention has high internal purity, the content of P and S harmful elements is extremely low, the anti-temper embrittlement coefficient J<50, and the normal temperature of the delivery state is 497MPa≤R _eL ≤512MPa, 605MPa≤R _m ≤620MPa, 460MPa≤R _m ≤480MPa at 370°C; 450MPa≤R _m(370°C) ≤470MPa, KV _2(80°C) ≥400J, T _NDT ≤ -40°C, CSR of HIC (A solution) is 0%, 264MPa·m ^1/2 ≤ KIC ≤ 269MPa·m ^1/2 .

In order to describe the present invention, the present invention has been properly and fully described through the examples above. The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. In the case of the spirit and scope of the invention, various changes and modifications can also be made, and any modifications, equivalent replacements, improvements, etc., should be included in the protection scope of the present invention, and the patent protection scope of the present invention should be determined by Claims limited.

Claims (9)

1. A wide and thick steel plate for the positioning of advanced nuclear power units, characterized in that the composition of the steel plate is as follows by weight percentage: C 0.13%~0.16%, Si 0.20%~0.30%, Mn 0.30%~0.60%, P ≤0.006 %, S ≤0.002%, Cr 2.55%~2.85%, Mo 0.80%~1.20%, Ni 1.20%~1.50%, Nb 0.04%~0.08%, V 0.10%~0.20%, Ti ≤0.03%, Alt≤0.02 %, Ca 0.001%～0.004%, N 0.01%～0.03%, Sn≤0.001%, H≤0.0001%, O≤0.0020%, the balance is Fe and unavoidable inclusions, high temperature tempering embrittlement resistance coefficient J=( Si+Mn)×(P+Sn)×10 ⁴ ≤50; the manufacturing method of a wide and thick steel plate for the positioning of advanced nuclear power units, including smelting, continuous casting, electroslag remelting, controlled rolling, controlled cooling, heat treatment; (1) Controlled rolling: controlled rolling is carried out in two stages; The first stage: heating + billet rolling; Heating is carried out before billet rolling, the heating temperature is controlled at 1180-1250°C, and the total heating time is 24-30 hours; The billet rolling of the steel ingot adopts the longitudinal-horizontal rolling strategy. The rolling passes in the longitudinal rolling stage are not more than 4 passes, the steel is turned at 90°, and the rolling is extended and rolled. The rolling passes in the horizontal rolling stage are less than 3 passes. The total number of passes is not more than 7, the reduction in a single pass is not less than 40mm, and the billet after blanking is 300~350mm; The second stage: heating + rolling; The billet is heated before rolling in the second stage. The heating temperature of the billet is controlled at 1180-1250°C for 6-8 hours, and the soaking time is 1.0-2.0 hours; The second stage of rolling is completed in the high-temperature recrystallization zone. The horizontal-longitudinal rolling strategy is adopted. During the horizontal rolling, the target width of direct rolling is more than 4800mm, the steel is turned at 90°, and the longitudinal rolling reaches the target thickness, and the cumulative reduction rate reaches more than 60%. , rolled to specifications (100~130)mm×(4500~5100)mm×Lmm; (2) Heat treatment: high temperature normalizing + sub-temperature quenching + high temperature tempering multiple heat treatment processes; High temperature normalizing: high temperature normalizing temperature is A _C3 + (100~150) ℃, holding time is 0.5min/mm ~1.0min/mm, air cooling to room temperature; Sub-temperature quenching: the sub-temperature quenching temperature is 800~850°C, the holding time is 0.5~1.5 min/mm, and then water-cooled, and the temperature of turning red is 350~450°C, and then air-cooled to room temperature; High temperature tempering: tempering temperature 710~730℃, holding time 60min+1.0~2.0 min/mm×T, T is the thickness of the steel plate, the unit is mm. 2. The wide and thick steel plate for positioning advanced nuclear power units according to claim 1, wherein the Mo/Si in the steel plate is 3~5, (Cr+Mn)/Mo is 2.5~4.0, and the steel plate The size length × width × height is L × (4500~5100) mm × (100~130) mm, L is the length of the steel plate, and the unit is mm. 3. A wide and thick steel plate for positioning advanced nuclear power units according to claim 1, characterized in that, after the first stage billet rolling in the step (1), the steel billets are off-line and stacked and slowly cooled, and the slow cooling temperature is ≥400℃, slow cooling time 48~72h. 4. The wide and thick steel plate for positioning of advanced nuclear power units according to claim 1, characterized in that, the high temperature normalizing temperature in the step (2) is 950°C~1000°C. 5. A wide and thick steel plate for positioning advanced nuclear power units according to claim 1, characterized in that the water cooling process parameters in the sub-temperature quenching process in the step (2) are: The water volume of the quenching unit is 120~150m ³ /min, the water pressure is 4~7bar, the upper and lower water ratio is 1: (1.5~2.5), swing watering, and the roller speed is 0.5~1.0m/s. 6. The wide and thick steel plate for positioning advanced nuclear power units according to claim 1, wherein the smelting process includes converter smelting, LF furnace refining, and RH refining; In the process of converter smelting, dephosphorization and decarburization are smelted separately by converter, in which dephosphorization and oxygen blowing are controlled at 7-10 minutes, and decarburization and oxygen blowing are controlled at 8-12 minutes; Deep desulfurization treatment is carried out during the LF refining process, and CaSi wire is fed into the steel for calcium treatment at the same time, the wire feeding speed is 200~350m/min, the wire feeding depth is 1.0~2.0m below the slag layer, and the thickness of the generated slag layer is 60~ 90mm, to ensure that inclusions fully float up; The degassing in the furnace is completed during the RH refining process, the net cycle time is 10-15 minutes, and the calming time before pouring is 3-5 minutes. 7. A wide and thick steel plate for positioning advanced nuclear power units according to claim 6, characterized in that steel scrap and molten iron are used as raw materials in the converter smelting process, and the content of molten iron is controlled at 70% to 80%. 8. A wide and thick steel plate for positioning advanced nuclear power units according to claim 1, characterized in that, the continuous casting: the superheat degree is 20~30°C, the billet goes off the assembly line and goes into stacking for slow cooling, and the stacking slow cooling time is 48~72h, destacking below 300℃. 9. A wide and thick steel plate for advanced nuclear power unit positioning according to claim 1, characterized in that, the electroslag remelting: the electroslag remelting steel ingot has a thickness and section of 500-700 mm, and the electroslag ingot is stacked slowly after demoulding. Cooling time 48~72h, destacking below 300℃ and air cooling.