High-performance gigapascal-grade marine steel resistant to marine atmospheric corrosion and manufacturing method thereof

Abstract

The application relates to the technical field of steel material preparation, in particular to a high-performance gigapascal-grade marine steel resistant to marine atmospheric corrosion and a manufacturing method thereof. C: 0.1%-0.15%, Si: 0.15%-0.25%, Mn: 1.0%-1.4%, P<=0.02%, S<=0.01%, Als: 0.02%-0.06%, Ni: 6.0%-9.0%, Cr: 0.5%-0.8%, Mo: 0.5%-0.8%, Cu: 0.4%-0.7%, Sn: 0.05%-0.2%, Sb: 0.05%-0.1%, V: 0.1%-0.18%, Ti: 0.01%-0.018%, and the rest is Fe and inevitable impurities. In combination with a casting machine heavy pressing + electroslag remelting + controlled rolling + quenching heat treatment + tempering heat treatment process, the thickness of the steel plate finished product can reach 80 mm, and the steel plate finished product has the properties of high-performance gigapascal-grade strength and resistance to marine atmospheric corrosion in an extremely cold deep sea environment.

Description

Technical Field

[0001] This invention relates to the field of preparation technology of marine engineering materials for extremely cold and deep sea environments, specifically to a high-performance gigapascal grade marine engineering steel resistant to marine atmospheric corrosion and its manufacturing method. Background Technology

[0002] In extremely cold and deep-sea environments, marine engineering equipment and structural materials face extremely harsh service conditions, including multiple challenges such as low temperatures (e.g., below -60°C), high pressure (deep-sea environment), high salt spray corrosion (marine atmosphere and seawater immersion), and dynamic loads (e.g., wave and ocean current impacts). In polar or deep-sea areas, ambient temperatures can drop to -60°C or even lower. Under such ultra-low temperature conditions, the toughness of traditional steel decreases sharply, making it prone to low-temperature brittle fracture. If the impact toughness of the material (e.g., Charpy V-notch impact energy) is insufficient, it may cause the structure to fail suddenly under dynamic loads, seriously threatening the safety of the equipment. For example, if the hull of polar vessels and the steel structure of deep-sea drilling platforms cannot meet the low-temperature toughness requirements, they are highly susceptible to catastrophic fractures when encountering iceberg collisions or low-temperature fatigue loads. As water depth increases, hydrostatic pressure rises significantly (approximately 0.1 MPa increases for every 10m increase in water depth). In deep-sea environments, pressure can reach tens of megapascals (MPa), which places higher demands on the compressive strength, creep resistance, and fatigue life of materials. In addition, high-pressure environments can accelerate the penetration of hydrogen into steel (hydrogen embrittlement risk) and may affect the transport rate of corrosive media, exacerbating the material's tendency for stress corrosion cracking.

[0003] Traditional marine engineering steel plates (such as ordinary carbon steel or low alloy steel) often struggle to maintain low-temperature toughness, corrosion resistance, and weldability when required for gigapascal-level high strength. This leads to problems such as brittle fracture, corrosion failure, or deterioration of weld joint performance in extremely cold and deep-sea applications, which seriously restricts the development of deep-sea resources, polar shipbuilding, and the construction of ocean-going infrastructure.

[0004] Chinese patent CN 113073263 B, entitled "An Ultra-High Strength Steel for Marine Engineering with a Fatigue Limit Greater Than 600 MPa and Its Preparation Method," proposes a marine engineering steel plate with a yield strength of 1000 MPa. It employs a low-C, low-Mn alloy composition system and uses conventional rolling and heat treatment processes, focusing on fatigue resistance. However, it cannot produce corrosion-resistant ultra-high strength steel plates with a thickness greater than 50 mm. Chinese patent application CN202411120190.0, entitled "A Gigapascal-Grade Marine Engineering Steel Plate for Extremely Cold and Ultra-Deep Environments and Its Manufacturing Method," proposes an ultra-high strength marine engineering steel plate with a yield strength of 1000 MPa. However, it uses a low-Ni, Cr, Mo, and Co alloy composition design, and the steel plate's strength cannot achieve the required corrosion resistance in marine environments. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a high-performance gigapascal marine engineering steel resistant to marine atmospheric corrosion and its manufacturing method. The finished steel plate thickness can reach 80mm. While ensuring ultra-high strength and high performance, it also has excellent resistance to marine atmospheric corrosion in extremely cold deep-sea environments.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A high-performance, gigapascal-grade marine engineering steel resistant to marine atmospheric corrosion in extremely cold, deep-sea environments is composed of the following chemical composition by weight percentage:

[0008] C: 0.1%~0.15%, Si: 0.15%~0.25%, Mn: 1.0%~1.4%, P≤0.02%, S≤0.01%, Als: 0.02%~0.06%, Ni: 6.0%~9.0%, Cr: 0.5%~0.8%, Mo: 0.5%~0.8%, Cu: 0.4%~0.7%, Sn: 0.05%~0.2%, Sb: 0.05%~0.1%, V: 0.1%~0.18%, Ti: 0.01%~0.018%, with the remainder being Fe and unavoidable impurities.

[0009] The effect of selecting the above alloying elements and their contents:

[0010] 1. Carbon (C), as a fundamental strengthening element in steel, improves the hardenability of steel plates during quenching in this invention. Too low a C content leads to a decrease in C solid solution content and carbide content, compromising the strength and hardenability of the steel plate. Too high a C content rapidly reduces the corrosion resistance of the steel plate. Furthermore, increased C content generates a large amount of hardened microstructure, reducing the elongation and low-temperature impact toughness of the steel plate. Therefore, the C content in the steel must be precisely controlled. Thus, this invention precisely controls the C content to 0.1%~0.15%.

[0011] 2. Si plays a solid solution strengthening role in steel. Adding a certain amount of Si to steel inhibits crystal growth, increases the hardness and strength of the steel plate, and improves its corrosion resistance. However, the addition of Si will reduce the low-temperature impact toughness of the steel plate. Therefore, in order to maximize the corrosion resistance and low-temperature toughness of the steel plate, this invention precisely controls the Si content to 0.15%~0.25%.

[0012] 3. Mn can dissolve in large quantities in the Fe matrix along with Ni and Cu, improving the strength and low-temperature toughness of the steel plate. Appropriate amounts of Mn can enhance the oxidation resistance and corrosion resistance of the steel plate. When the Mn content is below 1.0%, its contribution to the strength of the steel plate is relatively small. Furthermore, to improve the low-temperature toughness of the steel plate, it is necessary to reduce the impact of Mn segregation on the core performance of thick plates. However, this invention combines electroslag remelting and forging processes, allowing for a suitable increase in Mn content. Therefore, this invention precisely controls the Mn content between 1.0% and 1.4%.

[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. Al is the main deoxidizing element in steel. Excessive Al content will form large inclusions, affecting the low-temperature impact toughness of the steel plate. Therefore, the Al content should be minimized. Thus, this invention precisely controls the Al content to 0.02%~0.06%.

[0015] 6. Ni can significantly improve the low-temperature toughness and corrosion resistance of steel plates. A large addition can lower the ductile-brittle transition temperature of the steel plate; Ni has certain corrosion resistance, exhibiting good resistance to acidic marine environments, and works synergistically with elements such as Cr, Cu, and Sn to enhance the corrosion resistance of the steel plate. Simultaneously, Ni can reduce intergranular corrosion, improve the corrosion fatigue performance of the steel plate, and extend its service life. Therefore, this invention precisely controls the Ni content to 6.0%~9.0%.

[0016] 7. Cr can form a dense passivation film in steel, effectively preventing further oxidation of the metal surface, thus significantly improving the corrosion resistance of the steel plate. Combined with elements such as Ni, Sn, and Sb, excellent resistance to marine corrosion can be achieved even when the Cr content is below 13%. Cr effectively increases the strength of steel plates, and the Cr content can be appropriately increased; however, excessively high Cr content will deteriorate the impact toughness of the steel plate. Therefore, this invention precisely controls the Cr content to 0.5%~0.8%.

[0017] 8. Mo can significantly improve the strength and hardness of steel plates. This strengthening effect is particularly pronounced at high temperatures, resulting in higher yield strength and tensile strength. Mo significantly improves the corrosion resistance of steel, especially its resistance to pitting and crevice corrosion; adding an appropriate amount of Mo to heat-treated steel plates can enhance their corrosion resistance and resistance to pitting corrosion; Mo can also combine with carbides to reduce Cr precipitation, thereby improving the corrosion resistance of the steel plate; the combination of Mo, Ni, Cr, and other elements is a targeted design of this invention for specific effects. Therefore, this invention precisely controls the Mo content to 0.5%~0.8%.

[0018] 9. Copper compounds formed by Cu in steel exhibit high resistance to oxidation and sulfide corrosion, especially in corrosive media containing sulfides. Cu interacts with Cr in steel to form a dense oxide layer, enhancing the steel's resistance to atmospheric corrosion. In marine environments, the addition of Cu can inhibit corrosion and reduce biofouling in saline and humid conditions. Therefore, this invention precisely controls the Cu content to 0.4%~0.7%.

[0019] 10. Sn, in combination with Ni and Cr, can effectively improve the corrosion resistance of steel plates. However, adding too much Sn will exacerbate Cu embrittlement, leading to edge cracks in the steel plate during high-temperature rolling. Sn significantly promotes the second type of temper brittleness in alloy steel and reduces the low-temperature toughness of the steel plate. Therefore, this invention precisely controls the Sn content to 0.05%~0.2%.

[0020] 11. Sb can improve the hardness and strength of steel, inhibit intergranular corrosion, and enhance the corrosion resistance of steel plates. Sb works synergistically with other corrosion-resistant elements to form a dense oxide film, significantly hindering the penetration of Cl ions and improving the corrosion resistance of steel in harsh environments. In seawater environments, the corrosion-resistant effect of Sb is even more pronounced. Therefore, this invention precisely controls the Sb content to 0.05%~0.2%.

[0021] 12. Nitrogen (Nb) is a strong carbonitride forming element. Nb can improve the strength and hardness of steel plates; it can effectively delay the recrystallization of deformed austenite, prevent austenite grain growth, refine grains, and improve both strength and toughness; during the cooling process of the steel plate, a large amount of Nb (CN) precipitates, further promoting dislocation entanglement and refining grains. Nb can also stabilize CN compounds, improving the corrosion resistance of the steel plate. Therefore, this invention precisely controls the Nb content to 0.03%~0.06%.

[0022] 13. In steel, V acts in conjunction with elements such as C and N to refine grain size, thereby improving the strength and low-temperature toughness of the steel plate. During the heat treatment of quenched and tempered steel plates, V can effectively improve the high-temperature thermal stability of the steel plate, control abnormal austenite grain growth, and enhance the hardenability of the steel plate. Therefore, this invention precisely controls the V content to 0.1%~0.18%.

[0023] 14. Ti can combine with CN to form TiCN, a compound with high stability that can refine grains, thereby improving the strength and hardness of steel. Ti can also combine with carbon to form stable TiC, preventing the formation of chromium carbide at grain boundaries and improving the steel plate's resistance to intergranular corrosion. Therefore, this invention precisely controls the Ti content to 0.01%~0.018%.

[0024] The above-mentioned high-performance marine engineering steel with resistance to marine atmospheric corrosion in extremely cold deep-sea environments has a yield strength ≥1120MPa, tensile strength 1200~1390MPa, transverse elongation ≥17%, Charpy impact energy of the steel plate core at -84℃ ≥100J, and a maximum thickness of 80mm for the finished steel plate.

[0025] The microstructure at half the thickness of the steel plate consists of tempered troostite and retained austenite, with the tempered troostite lamellar spacing being 80-150 nm, the retained austenite content being 8%-10%, and the dislocation density being ≥1.e+10 / cm². 2 The proportion of large-angle grain boundaries is ≥50%, and the effective grain size of the tempered structure is 2~5μm.

[0026] The manufacturing method of a high-performance, gigapascal-grade marine engineering steel resistant to marine atmospheric corrosion in extremely cold deep-sea environments employs a process of high-cleanliness and alloying smelting + heavy pressure casting + electroslag remelting + controlled rolling + two quenching heat treatments + tempering heat treatment. The specific steps of this manufacturing method are as follows:

[0027] 1) Steel refining:

[0028] Molten steel is refined in a converter, LF furnace, RH or VD furnace to further reduce the content of P, S and non-metallic inclusions.

[0029] 2) Continuous casting:

[0030] During the casting process, two sets of compression rollers are used to apply heavy pressure to the front 1-2m of the core solidification zone. The pressure reduction of a single set of compression rollers is ≥8mm. The amount of secondary cooling water is controlled to make the surface cooling rate of the continuously cast billet 0.3~0.6℃ / s.

[0031] 3) Electroslag remelting:

[0032] Argon gas protection throughout the process, slag formation time 60-120 min, crystallizer thickness 300-450 mm, argon gas flow rate 15-30 m³ / h 3 / h, crystallizer water volume is 20~40m³ 3 / h, the cooling rate of the crystallizer is 0.5~1.0℃ / min, the feeding time is 4~7h, the slow cooling of the electroslag ingot after demolding is ≥72h, and the single-sided grinding amount of the upper and lower surfaces of the electroslag ingot is 5~20mm.

[0033] Electroslag remelting (ESR) technology, through precise control of alloy composition and protective atmosphere, significantly improves the corrosion resistance of alloys and the low-temperature toughness of the steel core. This ESR process utilizes protective slag, continuous atmosphere protection, and controlled crystallizer water flow and cooling rate to precisely adjust the alloy composition, effectively suppressing the intrusion of harmful gases and reducing alloy burn-off, thereby optimizing the uniformity of the alloy's internal composition. Adjusting the composition of the protective slag reduces segregation during the melting process; argon protection helps control oxygen content and improves corrosion resistance; and controlling the crystallizer cooling rate further suppresses impurities and gas oxidation in the alloy, effectively reducing the alloy potential difference and improving the steel plate's corrosion resistance. These comprehensive measures significantly enhance the alloy's corrosion resistance and significantly improve the low-temperature toughness of the steel core.

[0034] 4) High-temperature controlled rolling:

[0035] The continuously cast billet adopts a direct-loading process, where it is charged into the heating furnace at a temperature of 700-900℃ and held for 1-2 hours. This ensures consistent thickness-direction temperature during the low-temperature stage, preparing for a uniform microstructure in the high-temperature section. During subsequent heating, the billet's heating rate is controlled at 2-7℃ / min to prevent brittle defects within the billet. The heating temperature is then set at 1300-1400℃ and held for 2-6 hours. This high-temperature homogenization and holding ensures complete dissolution of C / N compounds and uniform heating throughout the thickness of the steel plate, allowing it to soften sufficiently.

[0036] The rolling temperature is 1200~1360℃, the average reduction per pass is 10%~20%, and the deformation rate is ≤1s. -1 The final rolling temperature is 1000~1250℃.

[0037] The high-temperature, low-deformation-rate rolling process design is based on the characteristics of high-temperature embrittlement elements such as Sn, Sb, and Mo specially added to the steel. At lower rolling temperatures, the steel plate has higher hardness and stiffness, resulting in greater rolling force, limiting rolling to the high-temperature stage. However, at high temperatures, Sn and Sb elements easily cause severe Cu embrittlement, so the steel plate should be rolled and deformed at a lower strain rate. This coordinated control of temperature and deformation rate constitutes the core technological innovation of the steel plate production process of this invention.

[0038] 5) Quenching, sub-temperature quenching, and tempering:

[0039] The quenching temperature is 900~1000℃, and the quenching holding time is 0.8~3.0 min / mm. The sub-critical quenching temperature is 600~800℃, and the sub-critical quenching holding time is 1.4~2.0 min / mm. The tempering temperature is 250~470℃, and the tempering holding time is 2.5~4.0 min / mm.

[0040] The purpose of quenching and tempering is to obtain a uniform and fine-grained tempered troostite and retained austenite microstructure, with a tempered troostite lamellar spacing of 80-150 nm, a retained austenite content of 8-10%, and a dislocation density ≥1.e+10 / cm². 2 With a high-angle grain boundary ratio of ≥50%, the effective grain size of the tempered structure is 2~5μm, which significantly improves the low-temperature impact toughness of the steel plate, while adjusting the strength and hardness of the steel plate and avoiding the precipitation of hard and brittle phases.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] 1. This invention, through synergistic innovation in composition, process, and microstructure, employs an alloy composition system combining elements such as C, Mn, Ni, Cr, Mo, Cu, Sn, and Sb with microalloying elements such as V and Ti. Combined with a process of heavy casting pressure, electroslag remelting, controlled rolling, quenching heat treatment, and tempering heat treatment, the resulting steel plate exhibits a yield strength ≥1120 MPa, tensile strength 1200~1390 MPa, transverse elongation ≥17%, and a Charpy impact energy at -84℃ ≥100 J. The maximum thickness of the finished steel plate is 80 mm. The microstructure at half the plate thickness consists of tempered troostite and retained austenite, with a tempered troostite lamellar spacing of 80~150 nm, a retained austenite content of 8~10%, and a dislocation density ≥1.e+10 / cm². 2 With a high-angle grain boundary ratio of ≥50%, an effective grain size of 2~5μm in the tempered structure, and excellent mechanical properties, this material achieves a balance between ultra-high strength, extreme cold toughness, long-term corrosion resistance, and weldability, providing key material support for major equipment such as deep-sea oil and gas platforms and polar icebreakers.

[0043] 2. This invention employs a compositional design that combines elements such as C, Mn, Ni, Cr, Mo, Cu, Sn, and Sb with microalloying elements such as V and Ti. Ni enhances the corrosion resistance of the steel plate, reduces intergranular corrosion, improves corrosion fatigue performance, and extends service life. Cr forms a dense passivation film in steel, effectively preventing further oxidation of the metal surface, thus significantly improving the corrosion resistance of the steel plate. Combined with elements such as Ni, Sn, and Sb, excellent resistance to marine corrosion can be achieved even with a Cr content below 13%. Mo significantly improves the corrosion resistance of steel, especially its resistance to pitting and crevice corrosion. Adding an appropriate amount of Mo to heat-treated steel plates enhances their corrosion resistance and resistance to pitting corrosion. The combination of Mo, Ni, and Cr is a targeted design of this invention for specific effects. Cu works synergistically with Cr in steel to form a dense oxide layer, enhancing the steel's resistance to atmospheric corrosion. In marine environments, the addition of Cu can inhibit corrosion and biofouling in saline and humid environments. Sn, in combination with Ni and Cr, can effectively improve the corrosion resistance of steel plates. Sb increases the hardness and strength of steel, inhibits intergranular corrosion, and enhances the corrosion resistance of steel plates. Ti can combine with carbon to form stable TiC, preventing the formation of chromium carbide at grain boundaries and improving the steel plate's resistance to intergranular corrosion.

[0044] 3. The electroslag remelting process utilizes protective slag, full-process atmosphere protection, and controlled crystallizer water flow and cooling rate to precisely adjust the alloy composition, effectively suppressing the intrusion of harmful gases and reducing alloy burn-off, thereby optimizing the uniformity of the alloy's internal composition. These comprehensive measures not only significantly improve the alloy's corrosion resistance but also significantly enhance the low-temperature toughness of the steel plate core.

[0045] 4. The high-temperature, low-deformation-rate rolling process design is based on the characteristics of high-temperature embrittlement elements such as Sn, Sb, and Mo specially added to the steel. When the rolling temperature is low, the steel plate has high hardness and stiffness, and the rolling force is large, so rolling can only be carried out at high temperatures. However, at high temperatures, Sn and Sb elements easily cause severe Cu embrittlement. Therefore, the steel plate should be rolled and deformed at a low strain rate. This coordinated control of temperature and deformation rate constitutes the core technological innovation of the steel plate production process of this invention.

[0046] 5. This invention employs quenching, sub-temperature quenching, and tempering heat treatment processes to obtain a uniform and fine-grained tempered troostite + retained austenite microstructure. The tempered troostite lamellar spacing is 80~150nm, the retained austenite content is 8%~10%, and the dislocation density is ≥1.e+10 / cm². 2 With a high-angle grain boundary ratio of ≥50%, the effective grain size of the tempered structure is 2~5μm, which significantly improves the low-temperature impact toughness of the steel plate, while adjusting the strength and hardness of the steel plate and avoiding the precipitation of hard and brittle phases. Attached Figure Description

[0047] Figure 1 This is a metallographic diagram of Embodiment 1 of the present invention. Detailed Implementation

[0048] This invention discloses a high-performance gigapascal-grade marine engineering steel resistant to marine atmospheric corrosion 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.

[0049] To address the compositional and performance requirements of a high-performance gigapascal (GMP) marine engineering steel resistant to marine atmospheric corrosion in extremely cold and deep-sea environments, this invention utilizes a combination of elements such as C, Mn, Ni, Cr, Mo, Cu, Sn, and Sb, along with microalloying elements like V and Ti, to design the composition and key production technologies for this high-performance GMP steel resistant to marine atmospheric corrosion in such environments. To achieve the objectives of this invention, extensive and systematic experimental research was conducted in several aspects, including alloy element screening and proportioning, steel cleanliness control, and optimization and parameter selection of efficient rolling processes. Ultimately, the alloy element proportions and production processes that meet the objectives of this invention were determined. The chemical composition of the steel in this invention's embodiments is shown in Table 1; the continuous casting and electroslag remelting processes in this invention's embodiments are shown in Table 2; the high-temperature rolling process in this invention's embodiments is shown in Table 3; the quenching, sub-temperature quenching, and tempering processes in this invention's embodiments are shown in Table 4; the mechanical properties of the steel plates in this invention's embodiments are shown in Table 5; and the corrosion resistance to marine environments in this invention's embodiments are shown in Table 6.

[0050] Table 1. Chemical composition (wt%) of steel in the embodiments of the present invention

[0051]

[0052] Table 2 Continuous casting and electroslag remelting processes in embodiments of the present invention

[0053]

[0054] Table 3 High-temperature rolling process of embodiments of the present invention

[0055]

[0056] Table 4 Quenching, sub-temperature quenching, and tempering processes in embodiments of the present invention.

[0057]

[0058] Table 5 Mechanical properties of steel plates in embodiments of the present invention

[0059]

[0060] Table 6. Corrosion resistance of the embodiments of the present invention in marine environments

[0061]

[0062] like Figure 1 As shown, the metallographic structure of Example 1, at half the thickness of the steel plate, is a tempered troostite + retained austenite structure, wherein the interlamellar spacing of the tempered troostite is 80~150nm, the content of retained austenite is 8%~10%, and the dislocation density is ≥1.e+10 / cm. 2 The proportion of large-angle grain boundaries is ≥50%, the effective grain size of the tempered structure is 2~5μm, and the mechanical properties are good.

[0063] As shown in Table 6, this invention is a high-performance marine engineering steel resistant to marine atmospheric corrosion, with a yield strength ≥1120MPa, tensile strength 1200~1390MPa, transverse elongation ≥17%, and Charpy impact energy of the steel plate core at -84℃ ≥100J. The seawater corrosion rate of the steel plate is ≤0.08g / hm. 2 Resistance to marine atmospheric corrosion rate ≤2.44 g / hm 2 The finished steel plates can be up to 80mm thick, possessing high-performance gigapascal strength and resistance to marine atmospheric corrosion in extremely cold and deep-sea environments. While ensuring ultra-high strength, they achieve a balance of extreme cold toughness, long-term corrosion resistance, and weldability, providing crucial material support for major equipment such as deep-sea oil and gas platforms and polar icebreakers.

[0064] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for manufacturing a high-performance, gigapascal-grade marine steel resistant to marine atmospheric corrosion, characterized in that, Marine engineering steel consists of the following chemical components in weight percentage: composition: C: 0.1%~0.15%, Si: 0.15%~0.25%, Mn: 1.0%~1.4%, P≤0.02%, S≤0.01%, Als: 0.02%~0.06%, Ni: 6.0%~9.0%, Cr: 0.5%~0.8%, Mo: 0.5%~0.8%, Cu: 0.4%~0.7%, Sn: 0.05%~0.2%, Sb: 0.05%~0.1%, V: 0.1%~0.18%, Ti: 0.01%~0.018%, with the remainder being Fe and unavoidable impurities; The manufacturing method of marine engineering steel specifically includes the following steps: 1) Steel refining; 2) Continuous casting: During the casting process, two sets of compression rollers are used to apply heavy pressure to the front 1-2m of the core solidification zone of the casting machine, with each set of compression rollers applying a pressure of ≥8mm. 3) Electroslag remelting: Argon gas protection throughout the process, slag formation time 60-120 min, crystallizer thickness 300-450 mm, argon gas flow rate 15-30 m³ / h 3 / h, crystallizer water volume is 20~40m³ 3 / h, the cooling rate of the crystallizer is 0.5~1.0℃ / min; 4) High-temperature controlled rolling: The rolling temperature is 1200~1360℃, the average reduction per pass is 10%~20%, and the deformation rate is ≤1s. -1 The final rolling temperature is 1000~1250℃; 5) Quenching, sub-temperature quenching, and tempering: The quenching temperature is 900~1000℃, the sub-temperature quenching temperature is 600~800℃, and the tempering temperature is 250~470℃.

2. The method for manufacturing a high-performance, gigapascal-grade marine steel resistant to marine atmospheric corrosion according to claim 1, characterized in that, The maximum thickness of the finished steel plate is 80mm, with a yield strength ≥1120MPa, tensile strength 1200~1390MPa, elongation ≥17%, Charpy impact energy of the steel plate core at -84℃ ≥100J, and seawater corrosion resistance ≤0.08g / hm. 2 Resistance to marine atmospheric corrosion rate ≤2.44 g / hm 2 .

3. The method for manufacturing a high-performance, gigapascal-grade marine steel resistant to marine atmospheric corrosion according to claim 1, characterized in that, The microstructure at half the thickness of the steel plate consists of tempered troostite and retained austenite, with the tempered troostite lamellar spacing being 80-150 nm, the retained austenite content being 8%-10%, and the dislocation density being ≥1.e+10 / cm². 2 The proportion of large-angle grain boundaries is ≥50%, and the effective grain size of the tempered structure is 2~5μm.

4. The method for manufacturing a high-performance, gigapascal-grade marine steel resistant to marine atmospheric corrosion according to claim 1, characterized in that, In step 1), molten steel is refined through a converter, LF furnace, RH or VD furnace.

5. The method for manufacturing a high-performance, gigapascal-grade marine steel resistant to marine atmospheric corrosion according to claim 1, characterized in that, 2) In this process, the surface cooling rate of the continuously cast billet is controlled at 0.3~0.6℃ / s.

6. The method for manufacturing a high-performance, gigapascal-grade marine steel resistant to marine atmospheric corrosion according to claim 1, characterized in that, 3) The feeding time is 4~7h, the electroslag ingot is demolded and slowly cooled for ≥72h, and the single-sided grinding amount of the upper and lower surfaces of the electroslag ingot is 5~20mm.

7. The method for manufacturing a high-performance, gigapascal-grade marine steel resistant to marine atmospheric corrosion according to claim 1, characterized in that, 4) The continuously cast billet is loaded into the heating furnace at 700~900℃ and held for 1~2 hours. The heating temperature is 1300~1400℃, the heating rate is controlled at 2~7℃ / min, and the holding time after reaching the temperature is 2~6 hours.

8. The method for manufacturing a high-performance, gigapascal-grade marine steel resistant to marine atmospheric corrosion according to claim 1, characterized in that, 5) The quenching holding time is 0.8~3.0 min / mm, the sub-temperature quenching holding time is 1.4~2.0 min / mm, and the tempering holding time is 2.5~4.0 min / mm.

Images