High-performance corrosion-resistant rack steel plate and manufacturing method thereof

Abstract

The present application relates to the technical field of corrosion-resistant rack steel plate, in particular to a high-performance corrosion-resistant rack steel plate and a manufacturing method thereof. The high-performance corrosion-resistant rack steel plate is composed of the following chemical components by weight percentage: C: 0.1%~0.15%, Si: 0.22%~0.45%, Mn: 1.1%~1.7%, P≤0.02%, S≤0.01%, Als: 0.03%~0.06%, Ni: 3.8%~5.5%, Cr: 0.7%~1.2%, Mo: 0.5%~0.9%, Cu: 0.25%~0.55%, Sn: 0.05%~0.15%, V: 0.05%~0.09%, Ti: 0.008%~0.02%, N: 0.004%~0.011%, and the rest is Fe and inevitable impurities. The high-performance corrosion-resistant rack steel plate with large thickness is produced by combining high cleanliness and special alloy smelting + casting machine light pressing down + electroslag remelting + forging breakdown + high-efficiency rolling + twice quenching + tempering process. The maximum thickness of the steel plate finished product is 210mm, the yield strength is greater than or equal to 690MPa, the tensile strength is 800~940MPa, the elongation is greater than or equal to 18%, the Charpy impact energy of the core of the steel plate at-40℃ is greater than or equal to 150J, and the corrosion resistance in the marine environment is excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of corrosion-resistant rack steel plates, in particular to a high-performance corrosion-resistant rack steel plate and a manufacturing method thereof. BACKGROUND

[0002] In recent years, with the rapid development of marine engineering, shipbuilding and offshore wind power, etc., the demand for high-performance corrosion-resistant rack steel plates is increasing. As a key transmission component, rack steel plates are widely used in offshore platform lifting systems, large cranes and deep-sea equipment, etc. They are exposed to high-salt mist, high humidity and strong corrosive marine environments for a long time, which easily causes corrosion fatigue, pitting and stress corrosion cracking, etc., seriously affecting their service life and safety.

[0003] Currently, traditional rack steel plates mostly use ordinary alloy steel or surface coating treatment (such as galvanizing, spraying anti-corrosion paint) to improve corrosion resistance. However, these methods have obvious shortcomings: ordinary alloy steel is prone to electrochemical corrosion in marine environments, leading to a decrease in mechanical properties; the surface protective layer is easily peeled off under long-term friction, impact or seawater scouring, losing its protective effect; some high-alloy corrosion-resistant steels (such as duplex stainless steel) are costly and have complex welding processes, making it difficult to be widely applied.

[0004] Chinese patent application "Thick-specification 800MPa hydroelectric steel with excellent core toughness and manufacturing method thereof" (application number CN202310778326.6) proposes a 150mm thick hydroelectric steel plate. The composition system of the steel is purified by low C, low Mn and Mg element deoxidization, which improves the cleanliness of the steel and thus improves the impact toughness of the steel. However, the production process still uses conventional smelting, rolling and heat treatment processes, without combining special processes such as casting press, electroslag remelting or forging, and without improving the excellent low-temperature toughness of 200mm or more thick steel plates by increasing alloy components. Chinese patent application "Production method of large-thickness quenched and tempered high-strength steel plate resistant to lamellar tearing" (application number CN202310903370.5) proposes a steel plate with excellent lamellar tearing resistance. The steel plate uses a low C, low Mn and low Ni alloy system. Although this scheme can significantly improve the lamellar tearing resistance of the steel plate, there are certain limitations in the composition design and production process: the conventional composition and process are only suitable for producing steel plates with a thickness of 150mm or less, and as the thickness increases, it is difficult to ensure the strength and toughness of the core and the low-temperature toughness; the steel plate has poor resistance to marine environment corrosion, limiting its application in harsh environments such as marine engineering. SUMMARY

[0005] In order to overcome the deficiencies of the prior art, the application provides a high-performance corrosion-resistant rack steel plate and a manufacturing method thereof, the steel plate has a maximum thickness of 210 mm, excellent mechanical properties, process performance and environmental adaptability, is more corrosion-resistant in seawater environment than a conventional EH690 offshore steel plate, and has a longer service life.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0007] A high-performance corrosion-resistant rack steel plate is composed of the following chemical components by weight percentage:

[0008] C: 0.1%~0.15%, Si: 0.22%~0.45%, Mn: 1.1%~1.7%, P≤0.02%, S≤0.01%, Als: 0.03%~0.06%, Ni: 3.8%~5.5%, Cr: 0.7%~1.2%, Mo: 0.5%~0.9%, Cu: 0.25%~0.55%, Sn: 0.05%~0.15%, V: 0.05%~0.09%, Ti: 0.008%~0.02%, N: 0.004%~0.011%, and the rest is Fe and inevitable impurities.

[0009] The component design reasons of the application are as follows:

[0010] 1. C can be dissolved in austenite to form a solid solution structure, combine with Fe to form carbide, and can improve the strength, hardness and wear resistance of the steel. With the increase of C element, the yield and tensile strength of the steel plate increases, but when the C content is higher than 0.15%, the low-temperature toughness decreases, and the seawater corrosion resistance and atmospheric corrosion resistance of the steel plate decrease. Therefore, the C content is accurately controlled to be 0.1%~0.15%.

[0011] 2. Si can improve the strength of the steel plate, and as a deoxidizer, it can reduce the O content. Si can form a dense and stable oxide film to improve the corrosion resistance. When the Si content is lower than 0.45%, the low-temperature toughness of the steel plate can be avoided. Therefore, the Si content is accurately controlled to be 0.22%~0.45%.

[0012] 3. Mn element has similar atomic radius with Fe, can be largely dissolved in Fe matrix to improve the strength of the steel plate. Mn can refine the grain structure of the steel plate, increase the number of grain boundaries, and improve the low-temperature impact toughness of the steel plate. When the Mn element is too high, the hardening effect of the Mn element will cause the low-temperature toughness of the core of the thick plate to decrease. In the application, the alloy strength is high, which is easy to cause segregation in the core of the blank, and the specific light pressing and electroslag remelting process can perfectly solve the problem of uneven composition and organization in the core of the blank. Therefore, the Mn content can be appropriately increased. Therefore, the Mn content is accurately controlled to be 1.1%~1.7%.

[0013] 4. P and S elements have no benefit to the mechanical properties of steel plates, especially elongation. P should be controlled to ≤0.02% and S to ≤0.01%.

[0014] 5. The phosphates in Als can react with oxides on the steel surface to form phosphate oxides, thereby preventing further oxidation of the steel. This reaction can effectively reduce the oxidation rate of the steel, extend its service life, and the protective film formed reduces the contact between the steel and the external environment, delaying corrosion. Therefore, this invention precisely controls the Al content to be 0.03%~0.06%.

[0015] 6. Ni can significantly improve the toughness and corrosion resistance of steel plates. A large addition results in a lower ductile-brittle transition temperature. Furthermore, the addition of Ni, in conjunction with microalloying elements such as V, further enhances the strength, toughness, and corrosion fatigue resistance of the steel plate. Ni also possesses certain corrosion resistance, exhibiting good resistance to acidic marine environments. Combined with elements such as Cr and Mo, it can improve the hot strength and corrosion resistance of steel. Therefore, this invention precisely controls the Ni content to be 3.8%~5.5%.

[0016] 7. The corrosion resistance of Cr in steel is mainly due to its ability to form a dense passivation film. This film effectively prevents further oxidation of the metal surface, thus significantly improving the corrosion resistance of the steel. Combined with elements such as Ni and Sn, it can achieve excellent resistance to marine corrosion even at low Cr content. Cr can also effectively increase the strength of steel plates. Appropriate addition of Cr can improve the cooling control effect of steel plates and increase the core heat transfer rate of extra-thick steel plates. However, excessive Cr content will produce a large amount of Cr carbides, reducing the impact toughness of the steel plate, and a large amount of Cr will cause temper brittleness in the steel plate after quenching and tempering. Therefore, this invention precisely controls the Cr content to 0.7%~1.2%.

[0017] 8. Mo can promote the passivation of the FeCr matrix and enhance corrosion resistance in reducing media, especially significantly enhancing resistance to chloride ion corrosion and pitting corrosion, effectively preventing pitting corrosion caused by the presence of chloride ions. Mo can also combine with carbides to reduce Cr precipitation, thereby improving the corrosion resistance of the steel plate. The combination of elements such as Mo, Ni, and Cr is a targeted design of this invention for specific effects. Mo can also improve the hardenability of the steel plate, and at the same time, Mo can form fine carbides in the steel, which can effectively improve the strength of the steel plate. Based on the alloy system of this invention, Mo content below 0.9% will not significantly reduce low-temperature toughness. Therefore, this invention precisely controls the Mo content to 0.5%~0.9%.

[0018] 9、Cu element cooperates with Cr, P and other elements in steel to form a dense oxide layer on the surface of the steel, which can significantly improve the atmospheric corrosion resistance of the steel. In marine environment, the addition of Cu can inhibit the pitting corrosion and uniform corrosion of the steel in the salt-containing humid environment, prolong the service life, and Cu element can also play a role in resisting biological adhesion. However, too high Cu element will cause cracks during heating of the steel billet, so the Cu content is accurately controlled to be 0.25%-0.55% in the application.

[0019] 10、Sn element in steel can cooperate with other elements to form a dense oxide film. This oxide film can significantly hinder the transmission of corrosive ions, thereby improving the corrosion resistance of the steel. Sn can enrich in the rust layer in the presence of chloride ions to form SnO2, which mainly enriches in the residual austenite zone and the grain boundary at the initial stage of corrosion, and gradually expands to the ferrite bainite region to form good corrosion resistance. Therefore, the Sn element content is accurately controlled to be 0.05%-0.15% in the application.

[0020] 11、V element is an important alloying element in the steel plate of the application, V element can refine the grain size and improve the strength and toughness of the steel plate. V element and C, N form V(C, N) particles in the matrix, which can refine and strengthen the grain. The addition of V element in the tempered steel plate can significantly improve the core strength and low temperature toughness of the steel plate. Therefore, the V content is accurately controlled to be 0.05%-0.09% in the application.

[0021] 12、Ti element can form TiCN with C and N, which has very high stability at high temperature and can effectively prevent grain growth, thereby refining the grain. Therefore, the Ti content is accurately controlled to be 0.008%-0.02% in the application.

[0022] 13、N element can cooperate with V and Ti elements to form fine and dispersed nitride precipitates, which can effectively promote the nucleation and growth of intragranular ferrite, and effectively control the growth of original austenite grains. However, when the solid solution N content is too high, the thermal plasticity and toughness of the steel will decrease. Therefore, the N content is accurately controlled to be 0.004%-0.011% in the application.

[0023] The maximum thickness of the above-mentioned high-performance corrosion-resistant rack steel plate finished product is 210mm, the yield strength is ≥690MPa, the tensile strength is 800-940MPa, the elongation is ≥18%, the Charpy impact energy of the core of the steel plate at-40℃ is ≥150J, the Brinell hardness HBW is ≥250, the seawater corrosion resistance of the steel plate is 40% lower than that of the conventional EH690 marine steel, and the marine atmospheric corrosion resistance is 50% lower than that of the conventional EH690 marine steel.

[0024] The microstructure at the thickness of 1 / 2 of the steel plate is lath bainite + residual austenite. The bainite lath spacing is 50-100 nm; the residual austenite content is 3%-8%; the effective grain size is 5-25 μm; and the mechanical properties are good.

[0025] The manufacturing method of the high-performance corrosion-resistant rack steel plate adopts high cleanliness and alloying smelting + casting machine light pressing + electroslag remelting + forging breakdown + high-efficiency rolling + twice quenching + tempering process, and specifically includes the following steps:

[0026] 1. Molten steel refining:

[0027] The molten steel is refined through a converter, an LF furnace, an RH or VD furnace to further reduce the contents of P, S and non-metallic inclusions.

[0028] 2. Continuous casting:

[0029] The casting superheat is 10-20 ℃, the casting machine light pressing amount is 4-6 mm, and the center segregation is C0.5. The main purpose of applying light pressing during continuous casting is to improve the quality and performance of the casting blank. By applying large deformation pressure at the solidification end of the continuous casting machine and fully utilizing the temperature difference between the thickness and temperature of the casting blank, the pressing amount can be efficiently transferred to the unevenly distributed position of the blank core, thereby effectively solving the problems of segregation, porosity and shrinkage holes. This process can significantly improve the density and chemical composition consistency of the casting blank, ensuring that the quality of the final product meets higher standards.

[0030] 3. Electroslag remelting:

[0031] The electroslag remelting slag time is 60-120 min, the crystallizer cooling rate is 0.5-1 ℃ / min, the feeding time is 6-8 h, and the electroslag ingot demolding slow cooling is ≥72 h. The electroslag remelting process has shown significant results in reducing alloy segregation, improving corrosion resistance and improving the mechanical properties of the core of the heavy steel plate. This process precisely controls the alloy composition by using protective slag, argon protection and deoxidizing agents, effectively inhibits the invasion of harmful gases and reduces alloy oxidation, thereby optimizing the composition uniformity of the alloy. The electroslag remelting process can reduce the segregation of the alloy during melting by adjusting the composition and form of the protective slag. Argon protection helps to control the oxygen content and prevent the alloy surface from being oxidized; and the deoxidizing agent further inhibits the oxidation of harmful impurities and gases in the alloy. These measures, combined, not only effectively reduce the alloy potential difference and enhance its corrosion resistance, but also more favorably improve the mechanical properties of the core of the heavy steel plate.

[0032] 4. Forging:

[0033] Forging heating temperature 1230~1280℃, forging open billet three direction compression, each direction reduction times not less than 3 passes, average single reduction ≥30mm, thickness direction deformation rate 40%~60%. The forging process can significantly improve the mechanical properties of the steel plate by controlling the temperature, optimizing the forging reduction and slow cooling, etc. Reasonable temperature control avoids material phase transition, reduces segregation and shrinkage, etc. Optimizing the forging reduction can homogenize the grain structure, improve the strength and toughness. The stacking slow cooling treatment reduces the internal stress and refines the grain, further improves the mechanical properties.

[0034] 5. Rolling:

[0035] The casting blank is loaded into the heating furnace at a furnace temperature of 600~700℃ and is kept for 30~60min. The purpose is to keep the thickness direction temperature of the steel blank consistent in the low temperature stage and prepare for the uniform structure in the high temperature stage. The heating temperature is 1200~1250℃ and the holding time is 120~180min. The rolling temperature is 1190~1240℃ and the single pass reduction is ≥40mm. The final rolling temperature is 1110~1220℃. The steel plate can deform more uniformly under the action of high temperature and large pressure, reducing the inhomogeneity in the microstructure, thereby improving the density and consistency of the material. The high temperature and large reduction rolling process can effectively improve the tensile strength and yield strength of the material, and reduce local stress concentration through high temperature treatment, thereby enhancing the low temperature toughness of the material. Through reasonable process parameter control, the high temperature and large reduction rolling process can complete the task of large-scale batch production in a short time, improving the production efficiency.

[0036] 6. Quenching and tempering:

[0037] The first quenching temperature is 850~920℃, the first quenching holding time is 1.2~1.8min / mm, the second quenching temperature is 830~880℃, the second quenching holding time is 1.4~2.0min / mm, the quenching steel plate core cooling rate is 0.4~0.8℃ / s, the tempering temperature is 570~670℃, and the tempering holding time is 3~4.5min / mm. The purpose of the first and second quenching is to refine the as-rolled structure and prepare for the tempering, further improve the grain size of the tempered structure, and improve the low temperature toughness of the steel plate core. The increase of the tempering temperature and the tempering holding time can refine and redistribute the fine precipitates, maximize the low temperature toughness and corrosion resistance of the steel plate while ensuring the strength of the steel plate.

[0038] Compared with the prior art, the beneficial effects of the present application are:

[0039] 1、The present application adopts C, Mn, Ni, Cr, Mo, Cu and Sn, N, V and other micro-alloying element composition design. The alloy strength is higher in the present application, which is easy to cause billet core segregation, and the specific light pressing down and electroslag remelting process can perfectly solve the problem of uneven composition and organization of billet core. The addition of Ni element greatly improves the toughness and corrosion resistance of the steel plate, and a lower ductile-brittle transition temperature is obtained by adding a large amount of Ni element, and the addition of Ni element and V and other micro-alloying elements together further improves the strength and toughness of the steel plate and the corrosion fatigue resistance; Ni has certain corrosion resistance and good corrosion resistance in marine acidic corrosion environment; combined with Cr, Mo, Sn, Cu and other elements, the hot strength and corrosion resistance of the steel are improved. The cooperation of Mo, Ni, Cr and other elements is the targeted design of the present application for special effect, which improves the hardenability of the steel plate, and Mo element in the steel can form fine carbide, which can effectively improve the strength of the steel plate; inhibit the pitting and uniform corrosion of the steel in the salt-containing humid environment, prolong the service life, and Cu element can also play the role of biofouling resistance.

[0040] 2、The present application has a casting superheat of 10~20℃, a casting machine light pressing amount of 4~6mm, effectively reduces the shrinkage cavity and shrinkage in the core of the billet, and the center segregation is C0.5. The main purpose of light pressing is to improve the quality and performance of the casting billet. By applying large deformation pressure at the solidification end of the continuous casting machine and fully utilizing the thickness and temperature difference of the casting billet, the pressing amount can be efficiently transferred to the core, thereby effectively solving the problems of segregation, porosity and shrinkage hole. This process can significantly improve the compactness and consistency of the chemical composition of the casting billet, and ensure that the quality of the final product reaches a higher standard.

[0041] 3、The present application has an electroslag remelting slag time of 60~120min, a crystallizer cooling rate of 0.5~1℃ / min, a feeding time of 6~8h, and an electroslag ingot demolding slow cooling≥72h. The electroslag remelting process shows remarkable effect in reducing alloy segregation, improving corrosion resistance and improving the mechanical properties of the core of the thick steel plate. The process precisely controls the alloy composition by using protective slag, argon protection and deoxidizing agent, effectively inhibits the invasion of harmful gas and reduces alloy oxidation, thereby optimizing the composition uniformity of the alloy, reducing the segregation generated during alloy melting, and preventing the alloy surface from being oxidized.

[0042] 4、The forging process of the present application significantly improves the mechanical properties of the steel plate by controlling the temperature, optimizing the forging pressing amount and slow cooling and other ways. Reasonable temperature control avoids material phase change, reduces segregation and shrinkage and other problems; optimizing the forging pressing amount can homogenize the grain structure, improve the strength and toughness; stack slow cooling treatment reduces internal stress and refines the grain, further improves the mechanical properties.

[0043] 5. This invention effectively improves the tensile strength and yield strength of materials through a high-temperature, high-reduction rolling process, and reduces local stress concentration through high-temperature treatment, thereby enhancing the low-temperature toughness of the material. With reasonable control of process parameters, the high-temperature, high-reduction rolling process can complete large-scale batch production tasks in a short time, improving production efficiency.

[0044] 6. The purpose of the primary and secondary quenching in this invention is to refine the rolled microstructure, prepare the microstructure for tempering, further improve the grain size of the tempered microstructure, and enhance the low-temperature toughness of the steel plate core. Increasing the tempering temperature and tempering holding time can refine and redistribute fine precipitates while ensuring the strength of the steel plate, thereby maximizing the low-temperature toughness and corrosion resistance of the steel plate.

[0045] In summary, this invention employs a composition design combining C, Mn, Ni, Cr, Mo, Cu, and microalloying elements such as Sn, N, and V. It utilizes a unique process involving high-purity alloying smelting, light pressing in casting, electroslag remelting, forging, high-efficiency rolling, double quenching, and tempering to produce thick, high-performance, corrosion-resistant rack steel plates. The maximum thickness of the finished steel plate is 210 mm, with a yield strength ≥690 MPa, tensile strength 800~940 MPa, elongation ≥18%, Charpy impact energy at -40℃ ≥150 J, and Brinell hardness HBW ≥250. The steel plate's seawater corrosion resistance rate is less than 40% of that of conventional EH690 marine engineering steel, and its marine atmospheric corrosion resistance rate is less than 50% of that of conventional EH690 marine engineering steel. Attached Figure Description

[0046] Figure 1 This is a metallographic diagram of Embodiment 1 of the present invention. Detailed Implementation

[0047] This invention discloses a high-performance corrosion-resistant rack steel plate and its manufacturing method. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0048] The chemical composition of the embodiments of the present invention is shown in Table 1. The continuous casting, electroslag remelting and forging processes of the embodiments of the present invention are shown in Table 2. The rolling process of the embodiments of the present invention is shown in Table 3. The quenching and tempering process of the embodiments of the present invention is shown in Table 4. The mechanical properties of the steel plates of the embodiments of the present invention are shown in Table 5. The corrosion resistance of the embodiments of the present invention and the comparative examples are shown in Table 6.

[0049] Table 1 Chemical composition (wt%) of embodiments of the present invention

[0050]

[0051] Table 2. Continuous casting, electroslag remelting, and forging processes in embodiments of the present invention.

[0052]

[0053] Table 3 Rolling process of embodiments of the present invention

[0054]

[0055] Table 4. Conditioning process in the embodiments of the present invention

[0056]

[0057] Table 5 Mechanical properties of steel plates in embodiments of the present invention

[0058]

[0059] Table 6 Corrosion resistance of embodiments and comparative examples of the present invention

[0060]

[0061] The full immersion test reference standard is JBT7901, and the salt spray test reference standard is GBT10125. The comparison steel composition is 0.011C~0.2Si~1.20Mn~0.6Ni~0.4Cr~0.2Mo~0.04Nb~0.04V~0.01Ti.

[0062] like Figure 1 As shown, the metallographic structure of Example 1, at half the thickness of the steel plate, consists of lath bainite and retained austenite. The bainite lath spacing is 50~100nm; the retained austenite content is 3%~8%, the effective grain size is 5~25μm, and it exhibits good mechanical properties.

[0063] This invention employs a composition design combining C, Mn, Ni, Cr, Mo, Cu, and microalloying elements such as Sn, N, and V. It utilizes a unique process involving high-purity alloying smelting, light pressing in a casting machine, electroslag remelting, forging, high-efficiency rolling, double quenching, and tempering to produce thick, high-performance, corrosion-resistant rack steel plates. The maximum thickness of the finished steel plate is 210 mm, with a yield strength ≥690 MPa, tensile strength 800~940 MPa, elongation ≥18%, Charpy impact energy of the core at -40℃ ≥150 J, and Brinell hardness HBW ≥250. As shown in Table 6, the seawater corrosion resistance rate of the steel plate is less than 40% of that of conventional EH690 marine engineering steel, and the marine atmospheric corrosion resistance rate is less than 50% of that of conventional EH690 marine engineering steel.

[0064] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A high-performance corrosion-resistant rack steel plate characterized by, consists of the following chemical components by weight percentage: C: 0.1%~0.15%, Si: 0.22%~0.45%, Mn: 1.1%~1.7%, P≤0.02%, S≤0.01%, Als: 0.03%~0.06%, Ni: 3.8%~5.5%, Cr: 0.7%~1.2%, Mo: 0.5%~0.9%, Cu: 0.25%~0.55%, Sn: 0.05%~0.15%, V: 0.05%~0.09%, Ti: 0.008%~0.02%, N: 0.004%~0.011%, the rest being Fe and inevitable impurities; The maximum thickness of the finished steel plate is 210mm, the microstructure at the thickness of 1 / 2 of the steel plate is lath bainite + residual austenite, the bainite lath spacing is 50~100nm, the residual austenite content is 3%~8%, and the effective grain size is 5~25μm; The manufacturing method of the steel plate specifically comprises the following steps: 1) steel refining; 2) continuous casting: The light press-down amount of the caster is 4~6mm; 3) electroslag remelting: The electroslag remelting slag melting time is 60~120min, the crystallizer cooling rate is 0.5~1℃ / min, and the feeding time is 6~8h; 4) forging: The forging heating temperature is 1230~1280℃, the forging cogging three-direction compression is carried out, the press-down times of each direction are not less than 3 passes, and the average single pass-down amount is ≥30mm; 5) rolling: The heating temperature is 1200~1250℃, and the holding time is 120~180min; The open rolling temperature is 1190~1240℃, the single pass-down amount is ≥40mm, and the finish rolling temperature is 1110~1220℃; 6) quenching and tempering: The first quenching temperature is 850~920℃, the first quenching holding time is 1.2-1.8min / mm; The second quenching temperature is 830~880℃, the second quenching holding time is 1.4~2.0min / mm, and the quenching steel plate core cooling rate is 0.4~0.8℃ / s; The tempering temperature is 570~670℃, and the tempering holding time is 3~4.5min / mm.

2. The high-performance corrosion-resistant rack steel plate according to claim 1, characterized in that: The yield strength is ≥690MPa, the tensile strength is 800~940MPa, the elongation is ≥18%, the steel plate core -40℃ Charpy impact energy is ≥150J, and the Brinell hardness HBW is ≥250. The manufacturing method specifically comprises the following steps:

3. A method of manufacturing a high-performance corrosion-resistant rack steel plate according to any one of claims 1 to 2, characterized by, 1) steel refining; 2) continuous casting: The light press-down amount of the caster is 4~6mm; 3) electroslag remelting: The electroslag remelting slag melting time is 60~120min, the crystallizer cooling rate is 0.5~1℃ / min, and the feeding time is 6~8h; 4) forging: The forging heating temperature is 1230~1280℃, the forging cogging three-direction compression is carried out, the press-down times of each direction are not less than 3 passes, and the average single pass-down amount is ≥30mm; 5) rolling: The heating temperature is 1200~1250℃, and the holding time is 120~180min; The open rolling temperature is 1190~1240℃, the single pass-down amount is ≥40mm, and the finish rolling temperature is 1110~1220℃; 6) quenching and tempering: ​ The primary quenching temperature is 850-920℃, and the primary quenching holding time is 1.2-1.8min / mm; The secondary quenching temperature is 830-880℃, the secondary quenching holding time is 1.4-2.0min / mm, and the core cooling rate of the quenched steel plate is 0.4-0.8℃ / s; The tempering temperature is 570-670℃, and the tempering holding time is 3-4.5min / mm.

4. The manufacturing method of the high-performance corrosion-resistant rack steel plate according to claim 3, characterized in that, 1) in which the molten steel is refined by a converter, an LF furnace, an RH or a VD furnace.

5. The manufacturing method of the high-performance corrosion-resistant rack steel plate according to claim 3, characterized in that, 2) in which the casting superheat is 10-20℃.

6. The manufacturing method of the high-performance corrosion-resistant rack steel plate according to claim 3, characterized in that, 3) in which the electroslag ingot demolding slow cooling is ≥72h.

7. The manufacturing method of the high-performance corrosion-resistant rack steel plate according to claim 3, characterized in that, 4) in which the thickness direction deformation rate is controlled to be 40%-60%.

8. The manufacturing method of the high-performance corrosion-resistant rack steel plate according to claim 3, characterized in that, 5) in which the cast blank is loaded into a heating furnace at a furnace temperature of 600-700℃, and the holding time is 30-60min.

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