CN117363981A - High-strength corrosion-resistant steel plate for 560 MPa-level ocean engineering and production method thereof - Google Patents

High-strength corrosion-resistant steel plate for 560 MPa-level ocean engineering and production method thereof Download PDF

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CN117363981A
CN117363981A CN202311302422.XA CN202311302422A CN117363981A CN 117363981 A CN117363981 A CN 117363981A CN 202311302422 A CN202311302422 A CN 202311302422A CN 117363981 A CN117363981 A CN 117363981A
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rolling
cooling
steel plate
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equal
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李文斌
赵坦
金耀辉
王晓航
朱隆浩
韩鹏
陈华
渠秀娟
李家安
郝未杰
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Angang Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/02—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling heavy work, e.g. ingots, slabs, blooms, or billets, in which the cross-sectional form is unimportant ; Rolling combined with forging or pressing
    • B21B1/026—Rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/02—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling heavy work, e.g. ingots, slabs, blooms, or billets, in which the cross-sectional form is unimportant ; Rolling combined with forging or pressing
    • B21B2001/028—Slabs

Abstract

The invention relates to a 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering and a production method thereof, wherein the steel plate comprises the following chemical components: 0.008 to 0.020 percent, si:0.10 to 0.25 percent of Mn:1.10 to 1.60 percent, P:0.025 to 0.035 percent, S is less than or equal to 0.009 percent, nb:0.01 to 0.015 percent, mo:0.45 to 0.55 percent, cr:0.90 to 1.20 percent of Ni:2.0 to 3.5 percent of Zr:0.005% -0.01%, co:0.02% -0.05%, als:0.075 to 0.085 percent, B:0.0006 to 0.002 percent, N:0.008% -0.012%; the balance of Fe and unavoidable impurities. The invention adopts ultra-low carbon design, and is compounded with Cr, mo, ni, zr, co and other multi-element alloy strengthening elements, and has the basic characteristics of high P, high Al and N, thereby improving the strength and low-temperature toughness of the steel plate and simultaneously ensuring that the steel plate has better corrosion resistance.

Description

High-strength corrosion-resistant steel plate for 560 MPa-level ocean engineering and production method thereof
Technical Field
The invention relates to the technical field of steel production for ocean engineering equipment manufacturing, in particular to a 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering and a production method thereof.
Background
Deep sea and polar region are reserved in strategic resources such as oil gas, combustible ice, mineral products and the like required by future development of human society, and the development of ocean economy in China is also advancing to deep and far sea and polar region cold regions. The steel for manufacturing ocean engineering equipment is in the transformation upgrading and product structure upgrading stages, such as the steel for ultra-high strength structure of a deep submersible, low-temperature corrosion-resistant steel suitable for polar environments and the like. However, these resource exploitation equipments have extremely high requirements for the performance of steel materials, such as higher strength, larger thickness, excellent low-temperature impact toughness, good Z-direction performance, etc., and also have better corrosion resistance. The existing steel is difficult to meet the performance requirements at the same time.
The Chinese patent application with application number 202011611587.1 discloses a steel plate for 690 MPa-grade ocean engineering and a manufacturing method thereof, wherein the yield strength Rp0.2 of the steel plate is larger than or equal to 690MPa (for example, 710-762 MPa), the tensile strength Rm is larger than or equal to 750MPa (for example, 760-793 MPa), the elongation after break A is larger than or equal to 16% (for example, 19% or more and 19.0% -23.0%), the reduction of area Z is larger than or equal to 60% (for example, 68% or more and 68.0% -79.0%), the impact power KV2 at-40 ℃ is larger than or equal to 150J, but the impact toughness at lower temperature is required in deep sea and polar regions, and the corrosion resistance problem is not solved.
The Chinese patent application with application number 202010557893.5 discloses a 550 MPa-level weather-resistant steel plate with excellent weldability and a manufacturing method thereof, wherein an optimized TMCP process is adopted, the yield strength of the steel plate is more than or equal to 460MPa, the tensile strength is more than or equal to 570MPa, the Charpy impact energy (single value) at-40 ℃ is more than or equal to 120J, the impact toughness KV2 at-40 ℃ is more than or equal to 100J, and the Akv at the welding Heat Affected Zone (HAZ) -40 ℃ is more than or equal to 100J. But the strength of the steel plate is low, the low-temperature toughness is only-40 ℃, and the corrosion resistance problem is not solved.
The Chinese patent application with application number 202110729039.7 discloses a high-strength steel with small compression ratio, high homogeneity, low yield ratio and 500MPa grade and a manufacturing method thereof, wherein the yield strength of a steel plate reaches more than 500MPa, the tensile strength reaches more than 600MPa, the yield ratio is not more than 0.85, the core grain size reaches more than 6.5 grade, and the product has the characteristics of low yield ratio, high homogeneity, high strength and toughness and the like. However, the performance index of the examples relates only to the impact toughness at-20 ℃ and does not relate to the corrosion resistance problem.
The Chinese patent application with the application number of 202010129784.3 discloses a high heat input welding EH550 MPa-level quenched and tempered marine steel and a manufacturing method thereof, wherein the yield strength of the quenched and tempered marine steel is more than or equal to 550MPa, the tensile strength is more than or equal to 670MPa, the impact energy (single value) of a base metal at-40 ℃ is more than or equal to 180J, but the impact toughness at lower temperature is required in deep sea and polar regions, and the corrosion resistance problem is not solved.
The Chinese patent application with the application number of CN201410036368.3 discloses a corrosion-resistant steel plate for a marine environment resistant to the south China sea and a production process thereof, wherein the production process comprises a converter smelting process, an LF refining process, a vacuum degassing process, a continuous casting process, a rolling control and cooling control process and the like, the structure type of the steel plate is theoretically a single-phase polygonal ferrite fine structure (average grain size of 10.17 mu m), the steel plate inevitably contains a very small amount of pearlite structure in industrial actual production, and compared with the conventional hull structural steel EH36, the corrosion resistance to the marine environment (marine atmosphere, tidal range, full immersion and the like) is improved by more than 50%, and the steel plate has good toughness matching and welding performance. However, the corrosion resistant steel sheet has low strength and insufficient low-temperature toughness.
Disclosure of Invention
The invention provides a 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering and a production method thereof, wherein the ultra-low carbon design is adopted, a Cr, mo, ni, zr, co multi-element alloy strengthening element is added in a compound manner, and the high P, the high Al and the N are taken as basic characteristics, so that the strength and the low-temperature toughness of the steel plate are improved, and meanwhile, the steel plate has better corrosion resistance; solves the problems of low strength, poor low-temperature impact toughness, insufficient corrosion resistance and small thickness specification of the steel plate for deep sea and polar regions.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
a560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering comprises the following chemical components in percentage by weight: 0.008 to 0.020 percent, si:0.10 to 0.25 percent of Mn:1.10 to 1.60 percent, P:0.025 to 0.035 percent, S is less than or equal to 0.009 percent, nb:0.01 to 0.015 percent, mo:0.45 to 0.55 percent, cr:0.90 to 1.20 percent of Ni:2.0 to 3.5 percent of Zr:0.005% -0.01%, co:0.02% -0.05%, als:0.075 to 0.085 percent, B:0.0006 to 0.002 percent, N:0.008% -0.012%; wherein Mn+145Nb is more than or equal to 2.5%, als/N is more than or equal to 6.5%, als+Si is more than or equal to 0.20%, cr+12Co is more than or equal to 1.15%, B+Zr is more than or equal to 0.005%, and P/Cr is more than or equal to 0.040 is more than or equal to 0.025; the balance of Fe and unavoidable impurities.
Further, the maximum thickness of the finished steel plate is 120mm, and the Z-direction performance is more than or equal to 35%.
Furthermore, the yield strength of the finished steel plate is 560-640 MPa, the elongation is more than or equal to 20%, and the impact energy at minus 80 ℃ is more than or equal to 150J.
Furthermore, the marine atmospheric corrosion resistance rate of the finished steel plate is less than 0.085mm/a, and the corrosion fatigue strength is more than or equal to 250MPa.
A production method of a 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering comprises the following technical processes:
(1) Smelting molten steel;
(2) Continuous casting; the superheat degree of the continuous casting tundish is controlled at 20-30 ℃; the whole process of continuous casting is protected and poured, the continuous casting blank drawing speed is less than 0.9m/min, and the specific water quantity of secondary cooling water is 0.80-0.90 m 3 The equiaxial crystal proportion of the continuous casting billet is more than 20.0 percent; the continuous casting process adopts light pressing, and the pressing amount is 6.0-10.0 mm;
(3) Cooling the continuous casting billet; quick cooling is adopted, the cooling temperature is 950-980 ℃, the cooling speed is 8.0-9.0 ℃/s, after cooling to 680-720 ℃, the mixture enters a slow cooling pit for slow cooling, and the mixture is cooled to below 150 ℃ at the cooling speed of 20.0-45.0 ℃/h;
(4) Heating the continuous casting billet; a sectional heating process is adopted; feeding the continuous casting blank into a furnace at the furnace temperature of 600-700 ℃, and preserving heat for more than 1.5 hours; a low-temperature section below 900 ℃ adopts a slow heating process, the heating speed is controlled to be 4-6 ℃/min, and the temperature is heated to 900 ℃; the temperature of 900 ℃ is higher than the high temperature section, a rapid heating-up and short-time heat preservation process is adopted, the temperature is heated to 1150-1180 ℃ at a heating speed of 8-12 ℃/min, and the heat preservation is carried out for 2.0-4.0 h;
(5) Rolling; three-stage rolling is adopted; the first stage rolling adopts a high Wen Man rolling plus high rolling reduction process, and the rolling speed is 1.0-2.0 m/s; the pass reduction rate is 12% -20%; the final rolling temperature of the first stage rolling is 1000-1080 ℃; the initial rolling temperature of the second stage rolling is 920-940 ℃, and the final rolling temperature of the second stage rolling is 820-840 ℃; the initial rolling temperature of the third stage rolling is 760-800 ℃, the rolling speed is 1.0-2.0 m/s, the pass reduction is 12-15%, and the final rolling temperature of the third stage rolling is 720-740 ℃;
(6) Cooling the rolled steel plate; an ultra-fast cooling and laminar cooling process is adopted; the cooling speed is 20.0-25.0 ℃/s during ultra-fast cooling, and the laminar cooling is carried out after the cooling to 250-350 ℃; the cooling speed during laminar cooling is 5.0-15.0 ℃/s, and the steel plate reddening temperature is less than 100 ℃;
(7) Tempering the steel plate; the tempering temperature is 600-650 ℃, and the furnace time is 2.0-4.0 min/mm.
Further, the specific process of molten steel smelting in the step (1) is as follows:
1) Adjusting the content of C, si, mn, P, S to be within a set range during converter smelting, and adding other alloy components for smelting;
2) Adjusting the content of other alloy components to be within a set range during refining of molten steel;
3) RH treatment is carried out on the refined molten steel, the RH treatment time is more than or equal to 40min, nitrogen is blown in the whole process during RH treatment, and the content of [ H ] in the steel is controlled to be less than or equal to 1.0ppm and the content of [ O ] in the steel is controlled to be less than or equal to 20ppm;
4) Zr and B elements are added 12-18 min before the RH treatment is finished, and the addition amount is 1.1-1.3 times of the target content.
Further, in the step (5), the continuous casting billet is discharged from the furnace and is directly rolled after descaling; in the first stage rolling process, rolling mill cooling water is adopted to cool the billet after each pass of rolling, and the cooling time is 5-8 s.
Further, in the step (5), the thickness of the blank to be heated after the rolling in the first stage is 1.5-3.0 times of the thickness of the finished steel plate, the blank to be heated is cooled by spraying water, the cooling speed is 6.0-8.0 ℃/s, and the blank to be heated is cooled to 10-20 ℃ above the rolling start temperature in the second stage; the thickness of the blank to be heated after the rolling in the second stage is 1.2-1.6 times of the thickness of the finished steel plate.
Compared with the prior art, the invention has the beneficial effects that:
1) Adopting an ultralow carbon design, adding Al, P, ni, cr, mo, zr, co and other alloy elements, and improving the strength, low-temperature toughness and corrosion resistance of the steel;
2) The continuous casting process is controlled, and the influence of segregation on the fatigue performance and the low-temperature performance of the steel plate is reduced; the heating process adopts a low internal stress controlled sectional heating process, the rolling process adopts a one-stage high Wen Man rolling and high-pressure rolling process, a two-stage recrystallization zone rolling and a three-stage low-temperature rolling process, and a subsequent UCC+ACC+tempering process is matched; the strength of the steel plate is ensured by means of dislocation strengthening, solid solution strengthening and second phase strengthening; the fine grain refinement is relied on to ensure the good low-temperature toughness of the steel plate; the steel plate is guaranteed to have good seawater corrosion resistance by means of temperature oxides formed by Cr, ni, zr, co and other elements;
3) The produced steel plate has better comprehensive mechanical property, the yield strength is 560-640 MPa, the elongation is more than or equal to 20 percent, and the impact energy at minus 80 ℃ is more than or equal to 150J;
4) The produced steel plate has better corrosion resistance, the marine atmospheric corrosion resistance rate is less than 0.085mm/a, and the corrosion fatigue strength is more than or equal to 250MPa;
5) The thickness specification range of the produced steel plate is large, the maximum thickness can reach 120mm, and the Z-direction performance is more than or equal to 35%.
Detailed Description
The invention relates to a 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering, which comprises the following chemical components in percentage by weight: 0.008 to 0.020 percent, si:0.10 to 0.25 percent of Mn:1.10 to 1.60 percent, P:0.025 to 0.035 percent, S is less than or equal to 0.009 percent, nb:0.01 to 0.015 percent, mo:0.45 to 0.55 percent, cr:0.90 to 1.20 percent of Ni:2.0 to 3.5 percent of Zr:0.005% -0.01%, co:0.02% -0.05%, als:0.075 to 0.085 percent, B:0.0006 to 0.002 percent, N:0.008% -0.012%; wherein Mn+145Nb is more than or equal to 2.5%, als/N is more than or equal to 6.5%, als+Si is more than or equal to 0.20%, cr+12Co is more than or equal to 1.15%, B+Zr is more than or equal to 0.005%, and P/Cr is more than or equal to 0.040 is more than or equal to 0.025; the balance of Fe and unavoidable impurities.
Further, the maximum thickness of the finished steel plate is 120mm, and the Z-direction performance is more than or equal to 35%.
Furthermore, the yield strength of the finished steel plate is 560-640 MPa, the elongation is more than or equal to 20%, and the impact energy at minus 80 ℃ is more than or equal to 150J.
Furthermore, the marine atmospheric corrosion resistance rate of the finished steel plate is less than 0.085mm/a, and the corrosion fatigue strength is more than or equal to 250MPa.
The invention relates to a production method of a 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering, which comprises the following technical processes:
(1) Smelting molten steel;
(2) Continuous castingThe method comprises the steps of carrying out a first treatment on the surface of the The superheat degree of the continuous casting tundish is controlled at 20-30 ℃; the whole process of continuous casting is protected and poured, the continuous casting blank drawing speed is less than 0.9m/min, and the specific water quantity of secondary cooling water is 0.80-0.90 m 3 The equiaxial crystal proportion of the continuous casting billet is more than 20.0 percent; the continuous casting process adopts light pressing, and the pressing amount is 6.0-10.0 mm;
(3) Cooling the continuous casting billet; quick cooling is adopted, the cooling temperature is 950-980 ℃, the cooling speed is 8.0-9.0 ℃/s, after cooling to 680-720 ℃, the mixture enters a slow cooling pit for slow cooling, and the mixture is cooled to below 150 ℃ at the cooling speed of 20.0-45.0 ℃/h;
(4) Heating the continuous casting billet; a sectional heating process is adopted; feeding the continuous casting blank into a furnace at the furnace temperature of 600-700 ℃, and preserving heat for more than 1.5 hours; a low-temperature section below 900 ℃ adopts a slow heating process, the heating speed is controlled to be 4-6 ℃/min, and the temperature is heated to 900 ℃; the temperature of 900 ℃ is higher than the high temperature section, a rapid heating-up and short-time heat preservation process is adopted, the temperature is heated to 1150-1180 ℃ at a heating speed of 8-12 ℃/min, and the heat preservation is carried out for 2.0-4.0 h;
(5) Rolling; three-stage rolling is adopted; the first stage rolling adopts a high Wen Man rolling plus high rolling reduction process, and the rolling speed is 1.0-2.0 m/s; the pass reduction rate is 12% -20%; the final rolling temperature of the first stage rolling is 1000-1080 ℃; the initial rolling temperature of the second stage rolling is 920-940 ℃, and the final rolling temperature of the second stage rolling is 820-840 ℃; the initial rolling temperature of the third stage rolling is 760-800 ℃, the rolling speed is 1.0-2.0 m/s, the pass reduction is 12-15%, and the final rolling temperature of the third stage rolling is 720-740 ℃;
(6) Cooling the rolled steel plate; an ultra-fast cooling and laminar cooling process is adopted; the cooling speed is 20.0-25.0 ℃/s during ultra-fast cooling, and the laminar cooling is carried out after the cooling to 250-350 ℃; the cooling speed during laminar cooling is 5.0-15.0 ℃/s, and the steel plate reddening temperature is less than 100 ℃;
(7) Tempering the steel plate; the tempering temperature is 600-650 ℃, and the furnace time is 2.0-4.0 min/mm.
Further, the specific process of molten steel smelting in the step (1) is as follows:
1) Adjusting the content of C, si, mn, P, S to be within a set range during converter smelting, and adding other alloy components for smelting;
2) Adjusting the content of other alloy components to be within a set range during refining of molten steel;
3) RH treatment is carried out on the refined molten steel, the RH treatment time is more than or equal to 40min, nitrogen is blown in the whole process during RH treatment, and the content of [ H ] in the steel is controlled to be less than or equal to 1.0ppm and the content of [ O ] in the steel is controlled to be less than or equal to 20ppm;
4) Zr and B elements are added 12-18 min before the RH treatment is finished, and the addition amount is 1.1-1.3 times of the target content.
Further, in the step (5), the continuous casting billet is discharged from the furnace and is directly rolled after descaling; in the first stage rolling process, rolling mill cooling water is adopted to cool the billet after each pass of rolling, and the cooling time is 5-8 s.
Further, in the step (5), the thickness of the blank to be heated after the rolling in the first stage is 1.5-3.0 times of the thickness of the finished steel plate, the blank to be heated is cooled by spraying water, the cooling speed is 6.0-8.0 ℃/s, and the blank to be heated is cooled to 10-20 ℃ above the rolling start temperature in the second stage; the thickness of the blank to be heated after the rolling in the second stage is 1.2-1.6 times of the thickness of the finished steel plate.
The 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering provided by the invention has the following effects of each chemical component and content selection and each element:
c: carbon is the most effective hardening element, can effectively improve the hardness of the quenched steel plate, and is the most effective alloy element for improving the strength of the quenched steel plate; carbon, chromium, molybdenum and zirconium belong to medium-strength carbide forming elements, can form alloy cementite such as (Fe.Cr) 3C and the like, can also form respective special carbides such as Cr7C3, cr23C6, coC, zrC and the like, have higher melting points, hardness, wear resistance and stability than Fe3C, and can effectively improve the strength of the steel plate. However, from the viewpoint of improving the plasticity, toughness and corrosion resistance of the ultra-high strength steel plate, the C content in the steel should be controlled to be lower as much as possible, so that the C content is controlled to be 0.008-0.020%.
Si: silicon is an essential element for steelmaking deoxidization, and when aluminum is used for deoxidization, a certain amount of silicon is added, so that the deoxidization capability of the aluminum can be obviously improved; si can improve the strength of the steel plate through solid solution strengthening; the marine corrosion resistance of the steel can be effectively improved due to the certain Si content; si is favorable for forming more superparamagnetic alpha-FeOOH phases in the rust layer, feO6 is distorted in the process of forming the alpha-FeOOH, the rust layer has excellent corrosion resistance in dry/wet alternate environments under different Cl ion environments, and the size of the alpha-FeOOH can be thinned, so that the marine corrosion resistance of steel can be effectively improved by a certain Si content. The Si content of the invention is controlled to be 0.10-0.25%.
Mn: manganese is a main element for improving strength and toughness, has very low cost and is a main additive element in steel; when the content of C is low, the higher Mn content can effectively improve the hardenability of the steel, and the strength of the steel plate is improved by refining the structure and promoting the transformation of bainite; however, too high an Mn content may deteriorate center segregation, drastically reduce the thermal conductivity of steel, increase the coefficient of linear expansion, form a large internal stress upon rapid heating or cooling, and increase the cracking tendency of the workpiece. Therefore, the Mn content of the invention is controlled to be 1.10-1.60 percent.
P: phosphorus is dissolved in ferrite, plays roles of solid solution strengthening and cold work hardening in steel, and is added into low alloy structural steel as an alloy element, so that the strength and the atmospheric corrosion resistance of the steel can be improved. P forms ferrophosphorus oxide with iron, oxygen and the like, and when the content of P is more than or equal to 0.02%, the corrosion resistance can be obviously improved. However, the biggest harm to improving the strength and hardness of the steel is that segregation is serious, tempering brittleness is increased, plasticity and toughness of the steel are obviously reduced, and other alloying elements for improving the toughness of the steel such as nickel and the like are required to be added, so that the P content of the invention is controlled to be 0.025% -0.035%.
S: sulfur is severely segregated in steel, and deteriorates the quality of steel. Sulfur is an inclusion forming element, and forms inclusions such as FeS and MnS, which reduce ductility of steel, and the vicinity of the inclusions becomes an origin of corrosion, which is disadvantageous for corrosion resistance of steel sheets. The invention controls the S content to be less than or equal to 0.009 percent.
N: nitrogen, which is a strong element for forming and stabilizing austenite, is about 20 times as effective as nickel, and can be used in steel in place of a portion of nickel to some extent; nitrogen penetrating into the surface of the steel and elements such as chromium, aluminum, vanadium, titanium and the like can be synthesized into extremely stable nitride, so that the nitrogen becomes a surface hardening and strengthening element, and the nitrogen enables the structure of the high-chromium and high-chromium nickel steel to be compact and firm, so that the strength and corrosion resistance of the steel can be remarkably improved. However, the residual nitrogen content in the steel is too high, so that macroscopic structure is loose or air holes are formed, a certain amount of Al is needed to be added in the nitrogen-containing steel (Als/N is controlled to be more than or equal to 6.5%), stable AlN is formed, and the defects that nitrogen escapes to form air holes during solidification and the like are avoided. Therefore, the N content in the invention is controlled to be 0.008-0.012%.
Al: aluminum is mainly used for deoxidizing and refining grains, aluminum and nitrogen or oxygen generate effective fine dispersoids to inhibit the growth of the grains when the steel is heated, and the aluminum plays a role in promoting the decomposition of austenite when the steel is cooled to improve the hardenability of the steel, and also becomes nucleation points of recrystallization to promote ferrite nucleation and refine the grains. AlN has high stability when being heated, so that the heat stability of the steel can be improved, the overheat tendency of the steel is reduced, and the oxidation resistance of the steel can be improved; aluminum generates an effective case hardening layer through lower temperature diffusion (nitriding) of nitrogen, and improves the oxidation resistance and corrosion resistance of steel; when aluminum is used for deoxidization, a certain amount of silicon is added, so that the deoxidization of the aluminum can be obviously improved (Als+Si is controlled to be more than or equal to 0.20 percent); however, if the amount of aluminum is excessive, abnormal structure of the steel is generated and graphitization tendency of the steel is promoted. Therefore, the Als content is controlled to be 0.075-0.085 percent.
Nb: the composite addition of Nb and Mn (controlling Mn+145Nb to be more than or equal to 2.5 percent) can effectively inhibit the recovery, recrystallization and other processes of austenite in the rolling process, on one hand, the austenite recrystallization temperature can be increased, the rolling temperature can be further increased, and the load of a rolling unit can be reduced; on the other hand, the phase transition structure of the steel plate can be effectively refined, and the strength and the low-temperature impact toughness can be further improved at the same time; nb can prevent intergranular corrosion of the steel by the oxidizing medium. The invention controls the Nb content to be 0.01% -0.015%.
Mo: the molybdenum has solid solution strengthening effect on ferrite, can improve the heat resistance and the hydrogen corrosion resistance of steel, improve the hardenability of the steel, enable parts with larger sections to be quenched deeply and completely quenched, improve the tempering resistance or tempering stability of the steel, and enable the parts to be tempered at higher temperature, thereby effectively eliminating (or reducing) residual stress and improving plasticity. The carbide of molybdenum is stable and can prevent other carbides from precipitating, so the effect of refining grains is strong, the overheat tendency of steel can be reduced, the strength, the hardness and the thermal stability are improved, and the thermal strength of pearlite heat-resistant steel is improved. Molybdenum can improve the intergranular corrosion resistance of Cr and Ni containing steel. However, excessive addition of molybdenum tends to graphitize the steel, embrittle the steel, reduce the strength and plasticity and deteriorate the toughness, so that the Mo content is controlled to be 0.45-0.55%.
Cr: chromium can improve the strength and hardness of the steel, and reduce the elongation and the reduction of area. The main function of chromium in quenched and tempered structural steel is to improve the hardenability, so that the steel has better comprehensive mechanical properties after quenching and tempering, and chromium-containing carbide can be formed, thereby improving the wear resistance of the material surface. Chromium is an element for improving the corrosion resistance of steel, but when Cr is singly added, the corrosion resistance is sometimes reduced, even worse than that of ordinary carbon steel, and when Cr is matched with other corrosion-resistant alloy elements such as P, the corrosion resistance can be obviously improved (the control of 0.040 percent is more than or equal to 0.025 percent of P/Cr). Therefore, the Cr content is controlled to be 0.90-1.20 percent.
Ni: nickel can strengthen ferrite and refine pearlite in steel. The pearlite is thinned due to the reduction of pearlite transformation temperature by nickel, and the amount of pearlite is large due to the reduction of carbon content of eutectoid point by nickel. Ni is used as an austenite stabilizing element, the Ar3 point temperature is reduced, and the size of a martensite/bainite structure is thinned, so that the Ni has the function of improving the strength, the elongation and the low-temperature toughness of the quenched and tempered steel plate; nickel can increase the resistance of steel to fatigue and reduce the susceptibility of steel to chipping; for high-strength and super-thick quenched and tempered steel plates, certain Ni content can ensure that the steel plates have enough hardenability and uniform plate thickness direction performance, and ensure the toughness matching and low-temperature toughness of the steel plates; ni steel is generally not easy to overheat, so that the growth of crystal grains at high temperature can be prevented, and the grain refinement is facilitated. The invention controls the Ni content to be 2.0% -3.5%.
Zr: zirconium is a strong carbide forming element, can improve the strength of steel, and the addition of a small amount of zirconium also has the effects of degassing, purifying and refining grains, is beneficial to the low-temperature performance of steel, improves the corrosion resistance and can eliminate the aging phenomenon. The Zr content is controlled to be 0.005-0.01%.
Co has the main solid solution strengthening effect in steel, can improve the strength and hardness of the steel, and improves the high temperature performance and the oxidation resistance and corrosion resistance of the steel. Co can increase the interaction between Fe atoms, reduce the critical concentration of Cr atoms forming clusters, and further improve the stability of Cr atom clusters; when Co and Cr atoms act on steel (Cr+12Co is controlled to be more than or equal to 1.15%), a smooth passivation film is formed on the surface of the steel, and the steel has high structural stability, can well protect a substrate, and therefore has excellent corrosion resistance. The Co content is controlled to be 0.02% -0.05% in the invention.
B, boron has strengthening effect on the grain boundary, and the boron is biased to the grain boundary, so that lattice defects and holes in the grain boundary area are reduced, and the free energy of the grain boundary is reduced; boron can reduce precipitates along grain boundaries and improve the grain boundary state; adding trace boron, zirconium or boron+zirconium (controlling B+Zr to be more than or equal to 0.005%) can delay the crack formation process on the grain boundary; the B element is added, so that the hardenability of the steel plate is ensured, and meanwhile, the weldability, the HAZ toughness and the surface quality of the plate blank are not damaged. The boron element improves the hardenability of the steel in the form of intragranular solid solution and grain boundary segregation. The invention controls the content of B to be 0.0006-0.002%.
The production process of the 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering comprises the following steps:
1. smelting steel according to set components, specifically comprising:
1) The content of C, si, mn, P, S and other elements is regulated to be within a set range during converter smelting, and other alloy components are added according to the requirements for smelting.
2) Refining the molten steel, and adjusting the content of other alloy elements to be within a set range.
3) RH treatment is carried out on refined molten steel, the RH treatment time is more than or equal to 40min, nitrogen is blown in the whole process during RH treatment, and the content of [ H ] in the steel is controlled to be less than or equal to 1.0ppm and the content of [ O ] in the steel is controlled to be less than or equal to 20ppm.
4) Zr and B elements are added 12-18 min before RH treatment is finished, and the addition amount is ensured to be 1.1-1.3 times of the target content.
2. Casting the molten steel obtained after smelting in the step 1 into a continuous casting blank, wherein a continuous casting tundish adopts a low superheat degree, and the superheat degree is 20-30 ℃ in order to control the content of equiaxial crystals in the continuous casting blank, refine the crystal grains of the continuous casting blank and reduce center segregation; the continuous casting is protected and poured in the whole process, the continuous casting blank drawing speed is less than 0.9m/min, and the cracks of the continuous casting blank can be effectively controlled; the specific water volume of the secondary cooling water is 0.80-0.90 m 3 Ensuring that the equiaxial crystal proportion of the continuous casting billet is more than 20.0 percent; in the continuous casting process, light pressing is adopted, the pressing amount is 6.0-10.0 mm, and the central loose defect can be effectively controlled.
3. In order to control the grain size of the continuous casting billet and improve the fine grain content of the casting billet, the continuous casting billet is rapidly cooled; the cooling temperature is 950-980 ℃, the cooling speed is 8.0-9.0 ℃/s, the continuous casting blank is cooled to 680-720 ℃ and then enters a slow cooling pit for slow cooling, and in order to reduce the internal stress of the continuous casting blank and control the cracks of the continuous casting blank, the continuous casting blank is cooled to below 150 ℃ at the cooling speed of 20.0-45.0 ℃/h.
4. And (3) feeding the continuous casting blank obtained in the step (3) into a heating furnace for heating. The heating adopts a sectional heating process, the continuous casting billet is fed into a furnace at the furnace temperature of 600-700 ℃, and the heat preservation is carried out for more than 1.5 hours, so that the internal stress of the continuous casting billet is further released, and the temperature of the continuous casting billet in the thickness direction is uniform. The low-temperature section (below 900 ℃) adopts a slow heating process to further release the internal stress in the cooling process of the continuous casting blank, reduce the thermal stress formed in the heating process of the casting blank, and fully dissolve back the precipitated phase in the steel at the same time so as to control the refinement of the prior austenite grains; the heating speed is controlled to be 4-6 ℃/min, and the temperature is heated to 900 ℃. The high temperature section (more than 900 ℃) adopts a rapid heating and short-time heat preservation process to prevent the excessive growth of austenite grains; the heating speed is controlled at 8-12 ℃/min, the temperature is heated to 1150-1180 ℃, and the heat preservation time is 2.0-4.0 h.
5. Rolling the continuous casting blank into a finished steel plate through three-stage rolling; in the first stage of rolling, in order to fully break columnar crystals of a continuous casting billet, a high Wen Man rolling and high reduction process is adopted. Directly rolling the continuous casting billet after discharging and descaling, wherein the rolling speed is 1.0-2.0 m/s, and the pass reduction rate is 12-20%; in the first stage rolling process, rolling mill cooling water is adopted to cool the billet after each pass of rolling, the cooling time is 5-8 s, and the final rolling temperature of the first stage rolling is 1000-1080 ℃. The thickness of the blank to be heated after the first stage rolling is 1.5 to 3.0 times of the thickness of the finished steel plate, in order to inhibit the growth of crystal grains of the intermediate blank, the blank to be heated is cooled by spraying water, the cooling speed is 6.0 to 8.0 ℃/s, and the blank to be heated is cooled to 10 to 20 ℃ above the rolling start temperature of the second stage rolling. The initial rolling temperature of the second stage rolling is 920-940 ℃, the final rolling temperature of the second stage rolling is 820-840 ℃, and the thickness of the blank to be heated is 1.2-1.6 times of the thickness of the finished steel plate. The initial rolling temperature of the third stage rolling is 760-800 ℃, the rolling speed is 1.0-2.0 m/s, the pass reduction is 12-15%, and the final rolling temperature of the third stage is 720-740 ℃.
6. The rolled steel plate adopts the process of ultra-fast cooling (UCC) +laminar cooling (ACC), the UCC cooling speed is 20.0-25.0 ℃/s, ACC cooling is adopted after cooling to 250-350 ℃, the ACC cooling speed is 5.0-15.0 ℃/s, the steel plate redness temperature is less than 100 ℃, fine grains after rolling can be kept, and the growth of the grains is prevented.
7. Tempering the cooled steel plate at 600-650 deg.c for 2.0-4.0 min/mm.
The following examples are given by way of illustration of detailed embodiments and specific procedures based on the technical scheme of the present invention, but the scope of the present invention is not limited to the following examples.
[ example ]
The chemical compositions of the steels of each example are shown in table 1, the continuous casting process parameters are shown in table 2, the heating process parameters are shown in table 3, the first stage rolling process parameters are shown in table 4, the second and third stage rolling process parameters are shown in table 5, the cooling process parameters are shown in table 6, and the properties of the finished steel plate are shown in table 7.
Table 1 chemical composition, wt% (except ratio) of steel
Examples C Si Mn P S Nb Als Mo Cr Ni
1 0.02 0.2 1.6 0.026 0.009 0.01 0.076 0.46 0.91 2.1
2 0.01 0.21 1.5 0.026 0.006 0.014 0.084 0.47 0.92 3.4
3 0.015 0.13 1.1 0.028 0.005 0.013 0.08 0.48 0.91 3.2
4 0.008 0.24 1.2 0.032 0.005 0.014 0.077 0.46 1.18 2.5
5 0.009 0.22 1.2 0.032 0.005 0.012 0.082 0.46 0.98 2.9
6 0.012 0.18 1.45 0.027 0.005 0.012 0.079 0.46 0.92 2.6
7 0.011 0.12 1.3 0.029 0.007 0.014 0.081 0.49 0.95 3.4
8 0.008 0.14 1.55 0.03 0.006 0.013 0.084 0.54 0.96 2.2
9 0.018 0.24 1.25 0.034 0.008 0.011 0.083 0.53 0.99 2.7
10 0.013 0.19 1.4 0.031 0.006 0.014 0.078 0.51 0.93 2.5
Examples Zr Co B N Cr+12Co B+Zr Mn+145Nb Als/N ALs+Si P/Cr
1 0.005 0.03 0.0006 0.008 1.27 0.0056 3.05 9.5 0.28 0.029
2 0.01 0.04 0.001 0.012 1.40 0.011 3.53 7.0 0.29 0.028
3 0.005 0.04 0.0008 0.011 1.39 0.0058 2.99 7.3 0.21 0.031
4 0.009 0.05 0.0008 0.009 1.78 0.0098 3.23 8.6 0.32 0.029
5 0.008 0.05 0.0006 0.009 1.58 0.0086 2.94 9.1 0.30 0.033
6 0.006 0.02 0.0009 0.0086 1.16 0.0069 3.19 9.2 0.26 0.029
7 0.007 0.03 0.0008 0.0092 1.31 0.0078 3.33 8.8 0.20 0.031
8 0.007 0.03 0.0008 0.011 1.32 0.0078 3.44 7.6 0.22 0.031
9 0.005 0.03 0.0008 0.0088 1.35 0.0058 2.85 9.4 0.32 0.034
10 0.009 0.04 0.0007 0.0093 1.41 0.0097 3.43 8.4 0.27 0.033
TABLE 2 continuous casting process parameters
TABLE 3 heating process parameters
Table 4 first stage rolling process parameters
TABLE 5 second, third stage Rolling Process parameters
Table 6 cooling process parameters
TABLE 7 Properties of finished Steel sheet
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims (8)

1. The 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering is characterized by comprising the following chemical components in percentage by weight: 0.008 to 0.020 percent, si:0.10 to 0.25 percent of Mn:1.10 to 1.60 percent, P:0.025 to 0.035 percent, S is less than or equal to 0.009 percent, nb:0.01 to 0.015 percent, mo:0.45 to 0.55 percent, cr:0.90 to 1.20 percent of Ni:2.0 to 3.5 percent of Zr:0.005% -0.01%, co:0.02% -0.05%, als:0.075 to 0.085 percent, B:0.0006 to 0.002 percent, N:0.008% -0.012%; wherein Mn+145Nb is more than or equal to 2.5%, als/N is more than or equal to 6.5%, als+Si is more than or equal to 0.20%, cr+12Co is more than or equal to 1.15%, B+Zr is more than or equal to 0.005%, and P/Cr is more than or equal to 0.040 is more than or equal to 0.025; the balance of Fe and unavoidable impurities.
2. The 560 MPa-grade high-strength corrosion-resistant steel plate for ocean engineering according to claim 1, wherein the maximum thickness of the finished steel plate is 120mm, and the Z-direction performance is more than or equal to 35%.
3. The 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering according to claim 1, wherein the yield strength of the finished steel plate is 560-640 MPa, the elongation is more than or equal to 20%, and the impact energy at-80 ℃ is more than or equal to 150J.
4. The 560 MPa-level high-strength corrosion-resistant steel plate for ocean engineering according to claim 1, wherein the ocean atmospheric corrosion resistance rate of the finished steel plate is less than 0.085mm/a, and the corrosion fatigue strength is more than or equal to 250MPa.
5. The method for producing a 560 MPa-level high-strength corrosion-resistant steel sheet for ocean engineering according to any one of claims 1 to 4, comprising the following steps:
(1) Smelting molten steel;
(2) Continuous casting; the superheat degree of the continuous casting tundish is controlled at 20-30 ℃; the whole process of continuous casting is protected and poured, the continuous casting blank drawing speed is less than 0.9m/min, and the specific water quantity of secondary cooling water is 0.80-0.90 m 3 The equiaxial crystal proportion of the continuous casting billet is more than 20.0 percent; the continuous casting process adopts light pressing, and the pressing amount is 6.0-10.0 mm;
(3) Cooling the continuous casting billet; quick cooling is adopted, the cooling temperature is 950-980 ℃, the cooling speed is 8.0-9.0 ℃/s, after cooling to 680-720 ℃, the mixture enters a slow cooling pit for slow cooling, and the mixture is cooled to below 150 ℃ at the cooling speed of 20.0-45.0 ℃/h;
(4) Heating the continuous casting billet; a sectional heating process is adopted; feeding the continuous casting blank into a furnace at the furnace temperature of 600-700 ℃, and preserving heat for more than 1.5 hours; a low-temperature section below 900 ℃ adopts a slow heating process, the heating speed is controlled to be 4-6 ℃/min, and the temperature is heated to 900 ℃; the temperature of 900 ℃ is higher than the high temperature section, a rapid heating-up and short-time heat preservation process is adopted, the temperature is heated to 1150-1180 ℃ at a heating speed of 8-12 ℃/min, and the heat preservation is carried out for 2.0-4.0 h;
(5) Rolling; three-stage rolling is adopted; the first stage rolling adopts a high Wen Man rolling plus high rolling reduction process, and the rolling speed is 1.0-2.0 m/s; the pass reduction rate is 12% -20%; the final rolling temperature of the first stage rolling is 1000-1080 ℃; the initial rolling temperature of the second stage rolling is 920-940 ℃, and the final rolling temperature of the second stage rolling is 820-840 ℃; the initial rolling temperature of the third stage rolling is 760-800 ℃, the rolling speed is 1.0-2.0 m/s, the pass reduction is 12-15%, and the final rolling temperature of the third stage rolling is 720-740 ℃;
(6) Cooling the rolled steel plate; an ultra-fast cooling and laminar cooling process is adopted; the cooling speed is 20.0-25.0 ℃/s during ultra-fast cooling, and the laminar cooling is carried out after the cooling to 250-350 ℃; the cooling speed during laminar cooling is 5.0-15.0 ℃/s, and the steel plate reddening temperature is less than 100 ℃;
(7) Tempering the steel plate; the tempering temperature is 600-650 ℃, and the furnace time is 2.0-4.0 min/mm.
6. The method for producing 560 MPa-grade high-strength corrosion-resistant steel plate for ocean engineering according to claim 5, wherein the specific process of molten steel smelting in the step (1) is as follows:
1) Adjusting the content of C, si, mn, P, S to be within a set range during converter smelting, and adding other alloy components for smelting;
2) Adjusting the content of other alloy components to be within a set range during refining of molten steel;
3) RH treatment is carried out on the refined molten steel, the RH treatment time is more than or equal to 40min, nitrogen is blown in the whole process during RH treatment, and the content of [ H ] in the steel is controlled to be less than or equal to 1.0ppm and the content of [ O ] in the steel is controlled to be less than or equal to 20ppm;
4) Zr and B elements are added 12-18 min before the RH treatment is finished, and the addition amount is 1.1-1.3 times of the target content.
7. The method for producing a 560 MPa-grade high-strength corrosion-resistant steel sheet for ocean engineering according to claim 5, wherein in the step (5), the continuous casting billet is directly rolled after being discharged from the furnace and descaled; in the first stage rolling process, rolling mill cooling water is adopted to cool the billet after each pass of rolling, and the cooling time is 5-8 s.
8. The method for producing 560 MPa-grade high-strength corrosion-resistant steel plate for ocean engineering according to claim 5, wherein in the step (5), the thickness of the blank to be heated after the rolling in the first stage is 1.5-3.0 times of the thickness of the finished steel plate, the blank to be heated is cooled by spraying water, the cooling speed is 6.0-8.0 ℃/s, and the blank to be heated is cooled to 10-20 ℃ above the rolling start temperature in the second stage; the thickness of the blank to be heated after the rolling in the second stage is 1.2-1.6 times of the thickness of the finished steel plate.
CN202311302422.XA 2023-10-10 2023-10-10 High-strength corrosion-resistant steel plate for 560 MPa-level ocean engineering and production method thereof Pending CN117363981A (en)

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