A 1300mpa grade heat resistant steel and a method of manufacturing the same

Abstract

The present application belongs to the field of wear-resistant steel production, and particularly relates to a 1300MPa-grade heat-resistant steel and a manufacturing method thereof. The chemical components in the steel are as follows in terms of percentage by weight: 0.39%<=C<=0.50%, 0.1%<=Si<=0.3%, 0.3%<=Mn<=0.8%, 0.8%<=Cr<=1.5%, 0.2%<=Mo<=0.8%, 0.0010%<=B<=0.005%, 0.05%<=Ti+Nb<=0.1%, 0.0020%<=RE<=0.0040%, 0.0010%<=N<=0.010%, 0.0005%<=Ca<=0.01%, P<=0.030% and S<=0.020%, and the balance is Fe and inevitable impurities. The yield strength of the steel plate is above 1300MPa at 500 DEG C, the tensile strength is above 1700MPa, the elongation is >=10%, and the impact energy Akv is >=20J.

Description

Technical Field

[0001] This invention belongs to the field of wear-resistant steel production, specifically relating to a 1300MPa grade heat-resistant steel and its manufacturing method. Background Technology

[0002] Existing wear-resistant steels are all heat-treated martensitic steels. The heat treatment process of quenching and tempering is complex, and the water or oil quenching process for thick steel plates is not well controlled, which can easily lead to defects such as uneven structure and hardness, easy cracking or poor plate shape.

[0003] On the other hand, ordinary heat-treated wear-resistant steel plates have poor high-temperature wear resistance. The combined effect of high temperature and wear leads to rapid material failure. For example, the hardness of ordinary wear-resistant steel plate NM400, which is widely used in metallurgy, power, mining, building materials and other industries, is only 290HB when heated to 400 degrees Celsius. The decrease in hardness under high temperature environment will significantly reduce its wear resistance and service life, affecting the service life of parts.

[0004] Patent application document 202210690770.8 discloses a wear-resistant steel plate and its manufacturing method. The disclosed technical content is as follows: C: 0.15-0.19%, Si: 0.22-0.35%, Mn: 11-1.7%, P: 0.007-0.015%, S: 0.001-0.015%, Cr: 0.15-0.35%, Mo: 0.11-0.17%, Ni: 0.015-0.045%, N≤0.01%, Al: 0.025-0.035%, Ca: 0.01-0.03%, Ti: 0.01-0.03%, V≤0.02%, B: 0.001-0.003%, Nd≤0.001%, with the balance being Fe and other unavoidable impurities. The performance of the wear-resistant steel plate is improved by adding V and Nd to conventional steel plate raw materials. The quenching and tempering process is prone to cracking when water-cooled, has poor weldability, and does not mention formability and high-temperature resistance.

[0005] Patent application document discloses a wear-resistant and heat-resistant steel and its preparation method, application number 201810636530.3. The disclosed technical content is as follows: C: 0.24-0.4%, Mn: 9.5-10.5%, Si: 1.5-1.9%, Nb: 0.7-1.20%, V: 0.5-0.8%, Cr: 19-21%, Ni: 5-6%, P: 0-0.045%, S: 0.2-0.3%, with the balance being Fe. It exhibits good heat and wear resistance, with a Brinell hardness between 230 and 285 HB, tensile strength ≥710 MPa, and elongation ≥16%. It possesses high hardness, high strength, and high toughness, making it suitable for various mining and construction machinery such as automobiles, bulldozers, loaders, excavators, and dump trucks. The high Mn and Cr / Ni content results in high costs. The added sulfur ore has a burn-off rate of 30%–35%, and the sulfur addition process employs three different time periods, making it complex and difficult to control. Molding performance and high-temperature performance are not mentioned.

[0006] Patent application document discloses a high-strength, high-wear-resistant NM600 steel plate and its production method, application number 201811516116.5. The disclosed technical content is as follows: the steel plate thickness is 12mm or more, C≤0.8%~1.2%, Si≤0.70%, Mn: 7.0%~8.5%, P≤0.025%, S≤0.010%, Cr: 2.0%~5.0%, Ni≤1.5%, Mo: 0.2%~2.5%, B≤0.004%, and the rest are Fe and residual elements. This invention relates to a high-carbon deformation-induced hardening wear-resistant steel. After quenching and tempering, this steel contains austenite in a metastable state. When the material surface is subjected to external pressure, impact, or friction, the surface austenite immediately transforms into deformation martensite, achieving rapid surface hardening and a dramatic improvement in wear resistance. Wear tests show that the average hardness at 50 μm from the wear surface (subsurface layer) is 570–650 HB. However, the high Cr content results in high cost, and the martensite transformation from metastable austenite in high-carbon steel is unstable and prone to defects such as cracks. Formability and high-temperature performance are not mentioned.

[0007] The patent application document, Martensitic High-Temperature Wear-Resistant Steel and its Production Method, application number 202010949264.7, discloses the following technical content: C: 0.18%~0.24%, Si: 0.1%~0.35%, Mn: 0.5%~11%, P<0.013%, S<0.004%, Als: 0.03%~0.06%, Nb: 0.025%~0.055%, V: 0.02%~0.04%, Ti: 0.01%~0.025%, Cr: 0.1%~0.35%, Mo: 0.25%~0.45%, B: 0.0005%~0.0018%, N: 0.003%~0.0045%, H<1.7ppm, Ca: 0.002%~0.004%, with the remainder being Fe and unavoidable impurities. The steel plate thickness ranges from 8mm to 30mm, with a room temperature Brinell hardness of 400HBW to 430HBW. The microstructure at 100℃ to 300℃ is clearly defined lath martensite. Mechanical properties at 100℃ to 300℃ include a tensile strength of 1250MPa to 1352MPa and a Brinell hardness of 388HBW to 420HBW. Its high-temperature, repeated low-stress impact wear resistance at 100℃ to 300℃ is 2.38 to 6.99 times better than conventional wear-resistant steel, meeting the service requirements of complex working conditions involving repeated impact and high-temperature wear at 100℃ to 300℃. The addition of nitrogen (B) employs a temperature-controlled and rate-controlled quenching process and a sub-temperature quenching heating process. The quenching and cooling process uses intermittent cooling, making the heat treatment process complex and difficult to control. Adding Nb, Ti, and V after heat treatment easily precipitates large particles, affecting impact resistance. Formability is not mentioned, the maximum temperature resistance is only 300℃, and impact resistance is not specified.

[0008] Patent application document describes a heat-resistant and wear-resistant steel plate, application number 201710068871.0. The disclosed technical content is as follows: C: 0.33%~0.40%, Si: 0.2%~0.4%, Mn: 0.80%~1.00%, Cr: 0.5~0.7%, Mo: 0.2~0.4%, Nb: 0.015%~0.03%, B: 0.0005~0.0022%, Ti: 0.10%~0.20%, Als: 0.015%~0.045%. It is characterized by medium carbon, Ti, and B microalloying, with the addition of Cr, Mo, Nb, B, and Ti, etc. The process involves continuous casting, slow cooling of slab stacks, and hot cleaning at 100~200℃. This process is complex and increases costs. The online quenching microstructure is martensitic, which is prone to cracking without tempering. Furthermore, martensitic wear-resistant steel has poor weldability and poor formability. The surface hardness of the plate after tempering at temperatures below 500℃ is greater than HB400, but impact resistance is not mentioned.

[0009] Patent application document discloses a heat-resistant and wear-resistant steel plate, application number CN201310105154.2, with the following technical content: C: 0.10~0.30%, Si: 0.10~1.50%, Mn: 0.50~2.00%, Cr: 0.30~2.00%, Mo: 0.10~1.50%, Ni≤1.00%, V≤0.10%, RE≤0.10%, W≤1.00%, Al: 0.010~0.080%, B: 0.0005~0.0040%, Ti≤0.80%, Ca≤0.0080%, N≤0.0080%, O≤0.0080%, H≤0.0004%. At least one rare earth element such as La, Ce, and Nd is added. The plate undergoes quenching followed by high-temperature tempering at above 400℃, resulting in a Brinell hardness greater than 360HB. Adding appropriate amounts of elements such as Cr, Mo, V, RE, and W improves the high-temperature resistance of the steel plate, ensuring that it retains good hardness at relatively high temperatures (300–600℃), and thus excellent wear resistance at higher temperatures. The tensile strength at 500℃ is greater than 1000 MPa. Specific hardness and impact performance at high temperatures are not mentioned. Alloys are often expensive. Martensitic wear-resistant steel has poor weldability and formability, and its hardness decreases after high-temperature tempering, resulting in low heat and wear resistance.

[0010] None of the aforementioned steel grades and production methods mention surface hardness uniformity control technology or high-temperature impact resistance. Therefore, existing materials are insufficient to meet the requirements, necessitating the development of heat-resistant and wear-resistant steels with controllable costs, excellent formability, and superior overall performance in terms of hardness and impact resistance at high temperatures. Summary of the Invention

[0011] To address the problem of poor wear resistance of existing wear-resistant steels at 500℃, leading to rapid material failure and short service life due to the combined effects of high temperature and wear, a 1300MPa grade heat-resistant steel and its manufacturing method are provided. This heat-resistant and wear-resistant steel plate exhibits excellent performance at 500℃, with a yield strength exceeding 1300MPa, a tensile strength exceeding 1700MPa, an elongation ≥10%, an impact energy Akv ≥20J, a surface hardness exceeding 58HRC, a surface hardness difference within ±0.5HRC, and a tensile strength difference within ≤10MPa within the same roll.

[0012] To achieve the above objectives, the present invention employs the following technical solution:

[0013] A 1300MPa grade heat-resistant steel has the following chemical composition by weight percentage: 0.39%≤C≤0.50%, 0.1%≤Si≤0.3%, 0.3%≤Mn≤0.8%, 0.8%≤Cr≤1.5%, 0.2%≤Mo≤0.8%, 0.0010%≤B≤0.005%, 0.05%≤Ti+Nb≤0.1%, 0.0020%≤RE≤0.0040%, 0.0010%≤N≤0.010%, 0.0005%≤Ca≤0.01%, P≤0.030% and S≤0.020%, with the balance being Fe and unavoidable impurities.

[0014] The thickness of the steel plate is 2 to 20 mm.

[0015] The steel plate has a yield strength of ≥1300MPa, a tensile strength of ≥1700MPa, an elongation of ≥10%, an impact energy of Akv ≥20J, a surface hardness of ≥58HRC, a surface hardness difference of ±0.5HRC, and a tensile strength difference of ≤10MPa within the same roll.

[0016] The following details the mechanism of action of each alloy component in the wear-resistant steel of this invention, where the percentage symbol % represents a weight percentage:

[0017] C: 0.39%~0.50%;

[0018] Carbon (C) is a major solid solution strengthening element in steel. In this invention, C reacts with Cr and Mo to form carbides, improving strength and hardness, especially high-temperature resistance, ensuring that hardness and wear resistance do not decrease at high temperatures. If the C content is below 0.39%, it is difficult to guarantee the hardness and hardenability of the steel plate after heat treatment. On the other hand, if the C content is above 0.5%, the strength is too high, affecting the yield strength ratio, deteriorating the toughness and plasticity of the steel, and making it prone to fracture. Therefore, the C content should be controlled between 0.39% and 0.5%.

[0019] Mn: 0.30%~0.8%;

[0020] Manganese (Mn) is relatively inexpensive and is an excellent deoxidizer and desulfurizer, essential for ensuring the strength and toughness of steel. Manganese and iron can form a solid solution indefinitely, increasing hardness and strength. Mn combines with sulfur (S) to form MnS, preventing hot cracking at grain boundaries that could affect the steel's hot formability. Mn is also a good deoxidizer and increases hardenability. Low Mn content in steel cannot meet the requirements for high strength and hardness, while excessive Mn content leads to severe segregation, affecting weldability and formability, and increasing production costs. Therefore, considering both cost and performance requirements, the Mn content should be controlled between 0.30% and 0.8%.

[0021] Si: 0.1%~0.3%;

[0022] Si is a common element in steel, used as a reducing agent and deoxidizer in the steelmaking process. Si is a ferrite-forming element, not a carbide-forming element. Si dissolved in ferrite improves hardenability and tempering resistance, increases strength and hardness, enhances wear resistance, significantly improves elastic limit, yield strength, and yield ratio, and increases fatigue strength, thus extending the service life of steel. However, a Si content exceeding 0.3% leads to surface decarburization and oxidation in steel, severely impacting its high-temperature wear resistance.

[0023] Cr: 0.8 ≤ Cr ≤ 1.5;

[0024] Cr is a medium-strong carbide-forming element. In this invention, the addition of Cr forms composite carbides with C and Mo, improving the stability of high-temperature hardness and wear resistance. Chromium also increases the temperatures of A3 and A1, shifts the GS line to the upper left, slows down A decomposition, and improves hardenability; it also enhances the oxidation resistance and corrosion resistance of steel.

[0025] Mo: 0.2≤Mo≤0.8;

[0026] Mo can increase the stability of supercooled austenite and improve hardenability. In this invention, Mo forms carbides with Cr, Ca, B, etc., which inhibit grain growth at high temperatures, hinder dislocation movement, improve oxidation and creep resistance, and enhance high-temperature strength and hardness. Moreover, Mo can reduce the segregation of alloying elements such as B and Cr at grain boundaries, thus reducing brittleness.

[0027] Ti+Nb: 0.05%~0.1%;

[0028] Ti and Nb are both grain-refining microalloying elements. One or both of them can be added. By controlling the Ti+Nb ratio within the range of 0.05% to 0.1%, grains can be refined, microsegregation can be suppressed, and the microstructure can be made more uniform. The above effects are not obvious below 0.05%, and above 0.10%, coarse precipitates are easily formed, which affects the impact resistance.

[0029] RE: 0.0020%~0.0040%;

[0030] RE is a strong oxidizing element that has a strong effect on removing inclusions and refining grains in steel. Controlling RE within the range of 0.0020% to 0.0040% can not only reduce inclusions in steel, but also refine grains, suppress microsegregation, homogenize the microstructure, reduce banding, and improve hardenability. This ensures the microstructure and hardness of the steel plate after heat treatment, and improves high-temperature toughness and impact resistance. Below 0.002%, the above effects are not obvious, while above 0.004%, coarse inclusions are easily formed, affecting impact resistance.

[0031] P: P≤0.030%, S≤0.020%;

[0032] Both phosphorus (P) and sulfur (S) are unavoidable harmful impurities in steel, and their presence severely degrades the steel's toughness. Therefore, measures must be taken to minimize the P and S content in steel. This invention limits the P content to ≤0.030%. The maximum S content is limited to 0.020% to reduce the formation of MnS.

[0033] Ca: 0.0005%~0.01%;

[0034] As a microalloying element, Ca forms composite carbides with Cr, Mo, RE, etc., which promotes the nucleation and spheroidization of carbides and improves high-temperature wear resistance and impact toughness.

[0035] N: 0.001% ≤ N ≤ 0.010%;

[0036] Nitrogen (N) is generally considered a harmful element, and the lower the N content in steel, the better. This invention employs a nitrogen-containing composition design. During refining, more than 0.001% N is introduced, causing N to react with Ti, Nb, V, Al, C, etc., to form fine particles ≤100nm, thereby improving high-temperature wear resistance and impact resistance.

[0037] B: 0.0010% ≤ B ≤ 0.005%;

[0038] B is an element that significantly improves hardenability. In this invention, a small amount of B is added to improve hardenability. At the same time, B forms composite carbides with Cr, Mo and other elements, which are dispersed in martensite and sorbite, promoting spheroidization of sorbite, refining martensite, improving hardness, and improving high-temperature wear resistance and impact toughness.

[0039] A method for producing 1300MPa grade heat-resistant steel specifically includes the following steps:

[0040] 1) The steel plate of this invention is rolled from a continuously cast billet smelted in a converter, refined in an LF electric furnace, and cast using a vertical bending arc continuous casting machine. The arc radius of the vertical bending continuous casting machine is not less than 5 meters. The billet thickness is 170-250 mm. The superheat of the tundish casting is 20-30°C. The continuous casting adopts light reduction and intermittent electromagnetic stirring. The light reduction is 5-10 mm, the interval is 3-8 min, the current is 400-1000 A, and the frequency is 2.2-2.9 Hz. The continuous casting speed is 0.9-1.8 m / min, the secondary cooling water ratio is 0.15-0.35 L / kg, the equiaxed crystal ratio is above 50%, and the micro-segregation of the alloy liquid at the end of the columnar crystals is controlled.

[0041] 2) The hot billet is fed into a walking beam furnace for heating; the furnace adopts a reducing atmosphere, the preheating section temperature is 500-600℃, the holding time is more than 30 minutes, the first heating section temperature is 900-1100℃, the second heating section temperature is 1200-1250℃, the soaking section temperature is 1200-1250℃, and the sum of the holding time of the second heating section and the soaking section is more than 50 minutes.

[0042] 3) High-pressure water descaling is used before roughing and finishing rolling, with a pressure of not less than 20MPa to ensure the surface quality of the steel plate; the total reduction in roughing rolling is 140-170mm, the initial rolling temperature is 1100-1200℃, and the temperature difference along the entire length of the steel strip is ≤20℃; the total reduction in finishing rolling is 50-70mm, the final rolling temperature is 900-960℃, and the temperature difference along the entire length of the steel strip is ≤10℃.

[0043] 4) After the steel plate exits the finishing mill, it enters laminar flow cooling. The front section is concentrated cooling with a cooling rate of 20-80℃ / s. The difference in cooling rate in the same position and the width direction is ≤10℃ / s. It is cooled to 550℃-650℃ and then coiled. It is then slowly cooled to below 300℃ at a cooling rate of 10-20℃ / h, and then air-cooled to obtain a fine spheroidized sorbite structure.

[0044] 5) Heat treatment: The steel strip is uncoiled at a speed of 1m / min to 3m / min, induction heated to 850 to 950℃, treated in a lead-bismuth mixture with a mass ratio of (3 to 4): 1 for 60 to 300 seconds, and rapidly cooled to below 300℃. The steel plate has a fine martensitic structure.

[0045] This invention employs converter smelting and LF electric furnace refining, eliminating the need for RH vacuum treatment. LF electric furnace refining involves adding other alloys after the sulfur content is ≤0.020%, while simultaneously purging nitrogen to adjust the nitrogen content in the molten steel. This alters the composition, quantity, and morphology of non-metallic inclusions, accelerates steel flow, promotes full inclusion flotation, and improves steel purity. The finished steel contains no more than grade 1.5 non-metallic inclusions, and the surface finish is improved, eliminating anisotropy in the microstructure. Continuous casting utilizes light reduction and intermittent electromagnetic stirring technology. The light reduction is 5–10 mm, the electromagnetic stirring current is 400–1000 A, and the frequency is 2.2–2.9 Hz. The tundish pouring superheat is 20–30 °C, controlling inclusions and segregation. The equiaxed crystal ratio of the billet is above 50%, and micro-segregation of the alloy liquid at the columnar crystal ends is controlled.

[0046] Meanwhile, the continuous casting speed is 0.9~1.8m / min, the secondary cooling water ratio is 0.15~0.35L / kg, ensuring that the surface temperature deviation of the billet is no more than 10℃, the billet cooling rate is uniform, the microstructure is uniform, and the strength difference of the rolled strip is ≤20MPa.

[0047] Hot charging and hot delivery of the billet reduces the surface temperature difference and mitigates microsegregation. The heating furnace uses a reducing atmosphere, with a preheating zone temperature of 500–600℃ and a holding time of at least 30 minutes. The first heating zone temperature is 900–1100℃, the second heating zone temperature is 1200–1250℃, and the soaking zone temperature is 1200–1250℃. The combined holding time for the second heating and soaking zones is at least 50 minutes to ensure the surface quality of the billet, prevent oxidation and decarburization, and simultaneously ensure the rolling temperature to form Cr-Mo-B carbides.

[0048] High-pressure water descaling is performed before rough and finish rolling, with a pressure of not less than 20 MPa, to ensure the surface quality of the steel plate.

[0049] The roughing mill has a total reduction of 140–170 mm and an initial rolling temperature of 1100–1200℃, providing nucleation energy for the precipitation of various carbides and nitrides. The strip rolling temperature difference is ≤20℃, resulting in uniform microstructure and properties. The finishing mill has a total reduction of 50–70 mm and a final rolling temperature of 900–960℃, which helps to obtain a sorbite microstructure after subsequent cooling, with banding not exceeding grade 2.0. The strip rolling temperature difference is ≤10℃, resulting in uniform microstructure and properties. The strip thickness fluctuation is within ±0.20 mm, and the crown is ≤40 μm. After exiting the finishing mill, the steel plate enters laminar flow cooling, with concentrated cooling in the front section at a cooling rate of 20–80℃ / s. The cooling rate difference along the width of the strip at the same location is ≤10℃ / s, ensuring uniform microstructure and properties within the same plate, with a strength difference ≤20 MPa. Cooling to 550℃~650℃ and then winding, followed by cooling at a rate of 10~20℃ / h to below 300℃, promotes carbide nucleation, resulting in a uniform and fine spheroidized sorbite structure, which prepares the material for heat treatment. Cooling rates exceeding 20℃ / h tend to form lamellar pearlite, while cooling rates below 10℃ / h tend to result in spheroidized sorbite that grows too large and has poor toughness and plasticity.

[0050] The steel strip is uncoiled at a speed of 1m / min to 3m / min, induction heated to 850 to 950℃, treated in a lead-bismuth mixture with a mass ratio of (3 to 4):1 for 60 to 300 seconds, and rapidly cooled to below 300℃. The resulting steel plate has a fine martensitic structure, high strength, uniform surface hardness, and excellent performance. At 500℃, the steel plate has a yield strength of over 1300MPa, a tensile strength of over 1700MPa, an elongation of ≥10%, an impact energy Akv ≥20J, a surface hardness of over 58HRC, a surface hardness difference within ±0.5HRC, and a tensile strength difference within the same roll ≤10MPa.

[0051] Compared with the prior art, the beneficial effects of the present invention are:

[0052] Steel plates produced according to the above chemical composition and process are alloyed with elements such as Cr, Mo, B, and RE. Simultaneously, process parameters such as smelting, continuous casting, billet heating, rolling temperature, reduction rate, coiling temperature, cooling rate, and heat treatment are controlled, resulting in no surface oxidation, decarburization, or intergranular oxidation. The steel plates exhibit a yield strength of over 1300 MPa, a tensile strength of over 1700 MPa, an elongation ≥10%, an impact energy Akv ≥20 J, a surface hardness of over 58 HRC, a surface hardness difference within ±0.5 HRC, and a tensile strength difference within ≤10 MPa within the same coil. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the specific implementation methods of this invention will be further described below in conjunction with the embodiments. The following embodiments are used to specifically illustrate the content of this invention. These embodiments are only general descriptions of the content of this invention and do not limit the content of this invention.

[0054] Table 1 lists the chemical composition of the steel in the examples, Table 2 lists the smelting and hot rolling production process parameters of the steel in the examples, Table 3 lists the carburizing treatment process of the steel in the examples, and Table 4 lists the properties of the hot-rolled plates and the carburized plates in the examples.

[0055] Table 1 Chemical composition of the examples, %

[0056]

[0057] Table 2. Smelting and hot rolling production process parameters (I) of the examples

[0058]

[0059] Table 2. Smelting and hot rolling production process parameters (II) of the Examples

[0060]

[0061] Table 3 Heat treatment process parameters for the examples

[0062]

[0063] Table 4. Steel Plate Properties in Examples

[0064]

[0065] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A 1300MPa grade heat-resistant steel, characterized in that, The chemical composition of the steel, by weight percentage, is as follows: 0.39%≤C≤0.50%, 0.1%≤Si≤0.3%, 0.3%≤Mn≤0.8%, 0.8%≤Cr≤1.5%, 0.2%≤Mo≤0.8%, 0.0010%≤B≤0.005%, 0.05%≤Ti+Nb≤0.1%, 0.0020%≤RE≤0.0040%, 0.0010%≤N≤0.010%, 0.0005%≤Ca≤0.01%, P≤0.030% and S≤0.020%, with the balance being Fe and unavoidable impurities; The production method of the 1300MPa grade heat-resistant steel specifically includes the following steps: 1) The superheat of the tundish casting is 20-30℃; the continuous casting speed is 0.9-1.8m / min; and the secondary cooling water volume is 0.15-0.35L / kg. 2) The billet is hot-charged into the heating furnace for heating; the preheating section temperature is 500-600℃, the holding time is more than 30 minutes, the second heating section temperature is 1200-1250℃, the soaking section temperature is 1200-1250℃, and the sum of the holding time of the second heating section and the soaking section is more than 50 minutes. 3) The total reduction in rough rolling is 140-170 mm, the initial rolling temperature is 1100-1200℃, and the temperature difference in the rolling of the steel strip along its entire length is ≤20℃; the total reduction in finish rolling is 50-70 mm, the final rolling temperature is 900-960℃, and the temperature difference in the rolling of the steel strip along its entire length is ≤10℃. 4) After the steel plate exits the finishing mill, it enters laminar flow cooling. The front section is concentrated cooling with a cooling rate of 20-80℃ / s. The difference in cooling rate along the width of the same position is ≤10℃ / s. The plate is cooled to 550℃-650℃ and then coiled. It is then slowly cooled to below 300℃ at a cooling rate of 10-20℃ / h, and then air-cooled. 5) Strip heat treatment: The strip uncoiling speed is 1m / min~3m / min, induction heating is carried out to 850~950℃, and it is treated in a lead-bismuth mixture with a mass ratio of (3~4):1 for 60~300s, and then rapidly cooled to below 300℃.

2. The 1300MPa grade heat-resistant steel according to claim 1, characterized in that, The thickness of the steel plate is 2 to 20 mm.

3. The 1300MPa grade heat-resistant steel according to claim 1, characterized in that, The steel plate has a yield strength of ≥1300MPa, a tensile strength of ≥1700MPa, an elongation of ≥10%, an impact energy Akv ≥20J, a surface hardness of ≥58HRC, and a surface hardness difference within ±0.5HRC at a high temperature of 500℃.

4. A method for producing 1300MPa grade heat-resistant steel as described in any one of claims 1-3, characterized in that, Specifically, the methods and steps are as follows: 1) The superheat of the tundish casting is 20-30℃; the continuous casting speed is 0.9-1.8m / min; and the secondary cooling water volume is 0.15-0.35L / kg. 2) The billet is hot-charged into the heating furnace for heating; the preheating section temperature is 500-600℃, the holding time is more than 30 minutes, the second heating section temperature is 1200-1250℃, the soaking section temperature is 1200-1250℃, and the sum of the holding time of the second heating section and the soaking section is more than 50 minutes. 3) The total reduction in rough rolling is 140-170 mm, the initial rolling temperature is 1100-1200℃, and the temperature difference in the rolling of the steel strip along its entire length is ≤20℃; the total reduction in finish rolling is 50-70 mm, the final rolling temperature is 900-960℃, and the temperature difference in the rolling of the steel strip along its entire length is ≤10℃. 4) After the steel plate exits the finishing mill, it enters laminar flow cooling. The front section is concentrated cooling with a cooling rate of 20-80℃ / s. The difference in cooling rate along the width of the same position is ≤10℃ / s. The plate is cooled to 550℃-650℃ and then coiled. It is then slowly cooled to below 300℃ at a cooling rate of 10-20℃ / h, and then air-cooled. 5) Strip heat treatment: The strip uncoiling speed is 1m / min~3m / min, induction heating is carried out to 850~950℃, and it is treated in a lead-bismuth mixture with a mass ratio of (3~4):1 for 60~300s, and then rapidly cooled to below 300℃.

5. The method for producing 1300MPa grade heat-resistant steel according to claim 3, characterized in that, The steel plate is rolled from a continuously cast billet produced by converter smelting, LF electric furnace refining, and casting on a vertical bending arc continuous casting machine. The arc radius of the vertical bending continuous casting machine is not less than 5 meters.

6. The method for producing 1300MPa grade heat-resistant steel according to claim 3, characterized in that, The continuous casting process employs light reduction and intermittent electromagnetic stirring. The light reduction is 5–10 mm, the electromagnetic stirring interval is 3–8 min, and the current is 400–1000 A.

7. The method for producing 1300MPa grade heat-resistant steel according to claim 3, characterized in that, High-pressure water descaling is used before both roughing and finishing rolling, with a pressure of not less than 20 MPa.

8. The method for producing 1300MPa grade heat-resistant steel according to claim 3, characterized in that, After air cooling in step 4), fine spheroidized sorbite structure is obtained.

9. The method for producing 1300MPa grade heat-resistant steel according to claim 3, characterized in that, After heat treatment, the steel plate has a fine martensitic structure.

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