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WO2024001078A1 - 一种80mm厚690MPa级超高强韧海工钢板及其制备方法 - Google Patents

一种80mm厚690MPa级超高强韧海工钢板及其制备方法 Download PDF

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WO2024001078A1
WO2024001078A1 PCT/CN2022/139834 CN2022139834W WO2024001078A1 WO 2024001078 A1 WO2024001078 A1 WO 2024001078A1 CN 2022139834 W CN2022139834 W CN 2022139834W WO 2024001078 A1 WO2024001078 A1 WO 2024001078A1
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steel plate
rolling
temperature
preparation
thick
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French (fr)
Inventor
麻衡
张庆普
王中学
王腾飞
张佩
何康
王月香
陈爱娇
刘军刚
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Shandong Iron and Steel Co Ltd
Laiwu Steel Group Yinshan Section Steel Co Ltd
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Shandong Iron and Steel Co Ltd
Laiwu Steel Group Yinshan Section Steel Co Ltd
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Application filed by Shandong Iron and Steel Co Ltd, Laiwu Steel Group Yinshan Section Steel Co Ltd filed Critical Shandong Iron and Steel Co Ltd
Priority to US18/878,783 priority Critical patent/US20250382690A1/en
Priority to JP2024576505A priority patent/JP2025523544A/ja
Priority to EP22949154.3A priority patent/EP4549606A1/en
Publication of WO2024001078A1 publication Critical patent/WO2024001078A1/zh
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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
    • C22C38/18—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
    • 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
    • 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
    • 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
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • 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
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • 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
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • 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
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur

Definitions

  • the invention belongs to the technical field of ultra-high strength marine steel production, and specifically relates to an 80mm extra-thick 690MPa grade ultra-high strength and toughness marine steel plate and a preparation method thereof.
  • Ci 0.10% ⁇ 0.17%
  • Si 0.25% ⁇ 0.45%
  • Mn 0.90% ⁇ 1.30%
  • S ⁇ 0.003%
  • P ⁇ 0.010% 0.1041% ⁇ 0.076%
  • Als 0.03% ⁇ 0.05%
  • N 0.004% ⁇ 0.013%
  • Ni 1.40% ⁇ 1.80%
  • Cr 0.60% ⁇ 1.00%
  • Mo 0.30% ⁇ 0.50%
  • Nb 0.021% ⁇ 0.04%
  • Cu 0.43% ⁇ 0.50%
  • Ti ⁇ 0.02%, in which more V, Cr, Mo, Cu and other elements are added.
  • a heat treatment process of quenching + sub-temperature quenching + tempering is required after rolling.
  • the patent application with publication number CN110846577A proposes a 690MPa grade medium manganese steel with a low yield ratio and its manufacturing method.
  • the composition contains 4.1% to 4.7% Mn element, and the large addition of Mn element will cause problems in steelmaking. And the continuous casting process brings huge difficulties. Continuous casting production is easy to cause accidents.
  • medium manganese steel has high low-temperature toughness, the rolled steel plates are prone to problems such as unqualified flaw detection and corner cracks.
  • the present invention aims to provide an 80mm 690MPa grade ultra-high-strength marine steel plate and a preparation method thereof.
  • the performance index of the 80mm 690MPa ultra-high-strength marine steel plate of the present invention meets the certification requirements of China Classification Society EH690 steel; at the same time, the -300mV (relative to Ag/AgCl reference electrode) saturated corrosion current density is ⁇ 1.90mA/cm 2 , The density of corrosion-active inclusions is ⁇ 9/mm 2 .
  • the product has excellent comprehensive properties such as high strength and toughness, low temperature resistance, and corrosion resistance.
  • the first aspect of the present invention provides a composition design of an 80mm690MPa grade ultra-high-strength marine steel plate, adopting the following technical solution:
  • An 80mm690MPa grade ultra-high-strength marine steel plate The chemical composition mass percentages in the steel plate are: C: 0.08% ⁇ 0.10%, Si: 0.20% ⁇ 0.30%, Mn: 1.10% ⁇ 1.25%, P ⁇ 0.007%, S ⁇ 0.002%, Nb: 0.020% ⁇ 0.030%, Ti: 0.010% ⁇ 0.020%, V: 0.030% ⁇ 0.045%, Cr: 0.40% ⁇ 0.60%, Ni: 1.40% ⁇ 1.50%, Cu: 0.15% ⁇ 0.25%, Mo: 0.25% ⁇ 0.35%, Als: 0.015% ⁇ 0.045%, the rest are Fe and inevitable impurity elements, control Pcm ⁇ 0.33%, Ceq ⁇ 0.64%.
  • Ceq C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15;
  • Pcm C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B.
  • the unavoidable impurity elements in terms of mass percentage are H ⁇ 0.0002%, O ⁇ 0.003%, N ⁇ 0.004%, and B ⁇ 0.0005 %, As ⁇ 0.006%, Sb ⁇ 0.010%, Sn ⁇ 0.020%, Pb ⁇ 0.010%, Bi ⁇ 0.010%.
  • the functions of the main alloys in the 80mm690MPa ultra-high-strength marine steel plate are as follows:
  • the Cr content in the present invention is controlled at 0.40% to 0.60%.
  • Ni is the element that most obviously improves the low-temperature toughness of extra-thick steel plates. Adding appropriate Ni can reduce the stacking fault energy of the crystal, facilitate the slip movement of dislocations, and improve the impact toughness; at the same time, Ni can promote the formation of dense protection on the surface of the steel plate. The rust layer is removed and the corrosion resistance of the steel plate is improved. However, too high Ni content is not conducive to ensuring welding performance. Therefore, the Ni content in the present invention is controlled at 1.40% to 1.50%.
  • the Cu can improve the corrosion resistance and strength of steel, improve weldability and machinability, etc. However, too high Cu content will increase the hot brittleness tendency of the steel plate. Therefore, the Cu content in the present invention is controlled at 0.15% to 0.25%.
  • Mo is an element that improves hardenability. It can expand the ⁇ phase area, delay the formation of precipitated ferrite, effectively improve the strength, and can also significantly improve the stability of the strength and toughness properties in the thickness direction of extra-thick steel plates. However, too high Mo content will deteriorate the weldability of the steel plate, so the present invention controls the Mo content to 0.25% to 0.35%.
  • Nb can effectively refine grains and can also play a role in precipitation strengthening; however, due to the limitation of C and the influence of heating temperature, Nb with too high content cannot be fully dissolved. Therefore, the Nb content in the present invention is controlled between 0.020% and 0.030%.
  • Ti can also have the effect of refining grains and precipitation strengthening, and significantly improves the low-temperature impact toughness of steel plates.
  • the present invention controls the Ti content between 0.010% and 0.020%.
  • V is a grain-refining element in steel and also has the effect of precipitation strengthening.
  • the addition amount is less than 0.02%, the effect is not obvious; when it is greater than 0.05%, the toughness and weldability of the steel are reduced. Therefore, the V content in the present invention is controlled between 0.030% and 0.045%.
  • Al can fix the free N in the steel and improve the low-temperature toughness of the steel plate and welded HAZ. Moreover, the dispersion and precipitation of AlN will inhibit the growth of austenite grains during the heating process, uniformly refine the austenite grain size, and improve the impact toughness. However, excessive Al content will increase the number of inclusions in the steel, increase the size of the inclusions, and reduce the internal quality of the steel plate, affecting the hot processing performance, welding performance and cutting performance of the steel. Therefore, the present invention controls the Al content within 0.020% ⁇ 0.050%.
  • Ceq Controlling the carbon equivalent index is beneficial to ensuring the strength and weldability of the steel plate.
  • the present invention controls Ceq ⁇ 0.64%.
  • Pcm Controlling the cold crack sensitivity coefficient is beneficial to ensuring the welding performance of the product.
  • the present invention controls Pcm ⁇ 0.33%.
  • Impurity elements in steel such as S, P, etc.
  • S and P contents are controlled below 0.005% and 0.010% respectively
  • B is easily enriched at grain boundaries, which reduces the low-temperature impact performance and fatigue performance of the steel plate, and also significantly increases the tendency of welding cracks. Therefore, B is controlled to be ⁇ 0.0005%;
  • other unavoidable impurity elements As ⁇ 0.006%, Sb ⁇ 0.010%, Sn ⁇ 0.020%, Pb ⁇ 0.010%, Bi ⁇ 0.010%, H ⁇ 0.0002%, O ⁇ 0.003%, N ⁇ 0.004%.
  • the second aspect of the present invention provides a method for preparing the above-mentioned 80mm690MPa grade ultra-high-strength marine steel plate, including converter smelting, LF+RH double refining, continuous casting, billet heating, rolling, and heat treatment, specifically:
  • Bottom-blown argon stirring is used throughout the process, aluminum particles, calcium carbide, and silicon carbide are used to adjust the slag, titanium wire is used to adjust the Ti component, and aluminum wire is used to adjust the Al component.
  • the alkalinity of the final slag is controlled to be above 2.5 as much as possible, and the LF refining time is ⁇ 50 minutes, among which the soft Blow time ⁇ 10min.
  • RH refining adopts this processing mode. Ensure that the vacuum degree is within 30Pa and the pure degassing time is ⁇ 5 minutes. After RH treatment, feed calcium aluminum wire 1-1.5m/t, soft blowing time ⁇ 14min, RH smelting time ⁇ 50min.
  • Full protection casting is adopted, using peritectic steel mold slag, the liquidus temperature is 1510 ⁇ 1520°C, the superheat is controlled within 20°C, the pulling speed of the 300mm thick continuous casting billet used is 0.70-0.90m/min, and it is cast in the sector section
  • the solidification end of the billet adopts light reduction technology, and the billet is placed in the pit and stacked for slow cooling for ⁇ 72 hours.
  • the billet is cold loaded into the furnace; a multi-stage heating and warming method is adopted, the soaking section temperature is 1190-1240°C, the soaking time is ⁇ 60min, the tapping temperature is 1200-1230°C, and the total heating and warming time is 290-310min. On the one hand, it ensures The cast slab is burned evenly and thoroughly while preventing excessive growth of austenite grains; before the hot cast slab is rolled, a high-pressure water dephosphorization treatment is performed.
  • the rolling process is a two-stage rolling process of rough rolling and finish rolling.
  • Rough rolling is recrystallization rolling, and the number of rough rolling passes is ⁇ 5, and the reduction rate of at least 2 passes (thickness reduction in a single pass/entry thickness, the same below) is ⁇ 19% to pass the large reduction.
  • the rate can fully refine the austenite grains, providing structural guarantee for improving the strength and toughness of thick steel plates.
  • the thickness of the intermediate billet after rough rolling is 120-130mm.
  • Finish rolling is non-recrystallized rolling, the finishing rolling opening temperature is 835-865°C, and the number of finishing rolling passes is ⁇ 7.
  • the number of finishing rolling passes is 5 to make full use of the number of passes.
  • the cumulative effect of deformation and the forced phase transformation mechanism induced by defects within the deformed austenite grains promote the emergence of a large number of deformation bands, twins and dislocations inside the austenite grains, creating conditions for ferrite phase deformation nuclei and making the steel plate Improved strength and toughness. Control the thickness of the intermediate billet obtained after rough rolling to reasonably distribute the reduction of rough rolling and finishing rolling, and improve the properties of the steel plate, especially the impact toughness of the core and the uniformity of properties in the thickness direction.
  • the cooling process is controlled to increase the ferrite nucleation rate and form fine and dispersed precipitates, further improving the strength and toughness of the steel plate.
  • the opening cooling temperature is 800 ⁇ 820°C
  • the final cooling temperature is 550 ⁇ 590°C
  • the cooling speed is controlled at 6 ⁇ 10°C/s.
  • the heat treatment method of quenching + high temperature tempering is adopted.
  • the Ac3 temperature of the steel plate of the present invention is about 850°C.
  • quenching heating temperature should be 30 ⁇ 50°C above Ac3.
  • the quenching temperature is set to 920 ⁇ 5°C to accelerate the dissolution of alloy carbides. Increase the stability of supercooled austenite and improve the hardenability of steel.
  • the heating time is 1.3 ⁇ 1.6min/mm ⁇ plate thickness, and the holding time is 30 ⁇ 3min.
  • the high-pressure water spray system of its cooling water system includes 2 sets of slit nozzles and 4 sets of high-density Type I nozzles with a length of 3640mm.
  • the low-pressure water spray system includes 18 Set of high-density type II nozzles, length 12600mm.
  • the water pressure in the high-pressure section is 0.7 ⁇ 0.9bar, and the water pressure in the low-pressure section is 0.3 ⁇ 0.4bar.
  • the roller speed of the quenching machine is 1.6-1.8m/min, the water volume in the high-pressure section is 5376-6067m 3 /h, and the water volume in the low-pressure section is 3499-3888m 3 /h;
  • the preferred process plan is,
  • the roller speed of the quenching machine is 1.6m/min, the water volume in the high-pressure section is 5376m 3 /h, and the water volume in the low-pressure section is 3888m 3 /h;
  • the roller speed of the quenching machine is 1.8m/min, the water volume in the high-pressure section is 6067m 3 /h, and the water volume in the low-pressure section is 3499m 3 / h.
  • the ratio of the water volume of the upper nozzle to the water volume of the lower nozzle is approximately 1:1.4 to ensure the symmetry and uniformity of the steel plate during the quenching process. In this way, through the cooling of the high-pressure section, the steel plate is fully quenched to complete all phase transformations, and the low-pressure section further takes away the heat conducted from the inside of the steel plate to the surface to prevent residual heat tempering, so that the temperature of the steel plate finally drops to room temperature.
  • High temperature tempering can eliminate the complex internal stress of the steel plate after rapid cooling quenching and make the steel plate have excellent comprehensive mechanical properties.
  • the tempering heating temperature is 600 ⁇ 5°C
  • the heating time is 2 ⁇ 2.5min/mm*plate thickness
  • the heat preservation time is 30 ⁇ 3min.
  • the main performance indicators are: yield strength ⁇ 690MPa, tensile strength 770 ⁇ 940MPa, elongation after break ⁇ 16%, -40°C core transverse impact energy ⁇ 100J, - 40°C CTOD ⁇ 0.15mm, -300mV (relative to Ag/AgCl reference electrode) saturated corrosion current density ⁇ 1.90mA/cm 2 , corrosion active inclusion density ⁇ 9/mm 2 .
  • the present invention provides high-quality cast slab raw materials by controlling the composition, purity and gas content in the steelmaking process; scientifically designs the heating, rolling, and post-rolling controlled cooling processes, and adopts two stages of large reduction and reasonable operation in the rough rolling stage. Measures such as reduction distribution are used to make the deformation penetrate into the core of the steel plate; the heat treatment process is optimized to obtain a high-strength and toughness structure throughout the thickness section, with excellent mechanical properties, transverse and longitudinal impact, aging impact and cold bending, and uniform performance in the thickness direction. Fully meets the certification requirements of EH690 steel of the classification society.
  • This invention utilizes high-clean molten steel smelting technology, high-penetration rolling technology and optimized heat treatment processes to obtain a low-inclusion, highly homogeneous structure with good corrosion resistance, greatly improving the corrosion potential of the steel plate matrix itself; at the same time, Cr+Cu+
  • Ni alloy element can effectively promote the formation of a dense, protective rust layer with good adhesion on the surface of the steel plate, preventing corrosive media such as H 2 O, O 2 and Cl - from penetrating into the steel matrix, ensuring that the product can survive in strong marine corrosive environments. service safety.
  • Figure 1 is a 500x metallographic structure near the surface of the steel plate prepared in Example 1 of the present invention
  • Figure 2 is a 500x metallographic structure at 1/4 of the thickness of the steel plate prepared in Example 1 of the present invention
  • Figure 3 is a 500x metallographic structure at 1/2 thickness of the steel plate prepared in Example 1 of the present invention.
  • Figure 4 is a -300mV (vs.Ag/AgCl) potentiostatic polarization curve of the steel plate prepared in Example 1 of the present invention
  • Figure 5 shows the corrosion active inclusions in the steel plate produced in Example 1 of the present invention under a 50x field of view.
  • the thickness of the final intermediate billet is 130mm; after the temperature reaches 845°C, the finishing rolling stage begins, with 7 passes of finishing rolling (pass 7 is empty); controlled cooling is performed at a speed of about 8°C/s, with an opening cooling temperature of 815°C and a final cooling temperature of 815°C. 590°C. After rolling, it is slowly cooled in the slow cooling pit for more than 48 hours. The quenching temperature is heated to 920°C and kept for 30 minutes. The roller speed of the quenching machine is 1.8m/min.
  • the water volume in the high-pressure section is 6067m 3 /h.
  • the water volume in the low-pressure section is 3499m 3 /h.
  • the ratio of the water volume in the upper nozzle to the water volume in the lower nozzle is 1:1.4.
  • the tempering heating temperature is 600°C and the temperature is kept for 30 minutes. It can be seen from Figures 1 to 3 that the near-surface structure is dominated by tempered sorbite. As it develops toward the center, the content of dispersed granular bainite, ferrite, and pearlite gradually increases. The inspection was carried out in accordance with the test methods and requirements in the China Classification Society's "Materials and Welding Rules" (2021). The main tensile properties and impact performance indicators are shown in Table 2, and the corrosion resistance performance indicators are shown in Table 3.
  • the intermediate billet The thickness is 120mm; after the temperature reaches 860°C, the finishing rolling stage begins, with 5 passes of finishing rolling; controlled cooling is carried out at a speed of about 10°C/s, with an opening cooling temperature of 803°C and a final cooling temperature of 559°C. After rolling, it is slowly cooled in the slow cooling pit for more than 48 hours.
  • the quenching temperature is heated to 920°C and kept for 30 minutes.
  • the roller speed of the quenching machine is 1.6m/min.
  • the water volume in the high-pressure section is 5376m 3 /h.
  • the water volume in the low-pressure section is 3888m 3 /h.
  • the ratio of the water volume in the upper nozzle to the water volume in the lower nozzle is 1:1.4.
  • the tempering heating temperature is 600°C and the temperature is kept for 30 minutes.
  • the present invention uses an embodiment of the quenching machine adjustment process as a comparative example to illustrate.
  • Comparative Example The smelting and casting implementation methods are the same as those in Example 2.
  • the casting billet is heated.
  • the heating and tapping temperature of the continuous casting billet is 1230°C.
  • the furnace time is 290 minutes.
  • the reduction rates of the 4th and 5th passes are 20.0% and 21.6% respectively.
  • the intermediate billet The thickness is 120mm; after the temperature reaches 850°C, the finishing rolling stage begins, with 5 passes of finishing rolling; controlled cooling is carried out at a speed of about 10°C/s, the opening cooling temperature is 805°C, and the final cooling temperature is 562°C.
  • the quenching temperature is heated to 920°C and kept for 30 minutes.
  • the roller speed of the quenching machine is 2.0m/min.
  • the water volume in the high-pressure section is 6255m 3 /h.
  • the water volume in the low-pressure section is 3287m 3 /h.
  • the ratio of the water volume in the upper nozzle to the water volume in the lower nozzle is 1:1.4.
  • the tempering heating temperature is 600°C and the temperature is kept for 30 minutes.
  • Table 2 shows the tensile properties and impact properties of the steel plates obtained in Examples and Comparative Examples.
  • the steel plate prepared according to the method of the present invention has a yield strength of ⁇ 690MPa, a tensile strength of 770-940MPa, an elongation after break of ⁇ 16%, a -40°C transverse impact energy of ⁇ 100J, and good performance uniformity in the thickness direction.
  • the strength and toughness of the comparative example are obviously lower than those of the examples, especially the 1/4 thickness and core impact properties cannot meet the performance requirements of E690 steel.
  • Table 3 shows the corrosion resistance performance indicators of the steel plates obtained in Examples and Comparative Examples.
  • the saturated corrosion current density was measured using an Autolab electrochemical workstation. A three-electrode system was used. The Ag/AgCl electrode was the reference electrode and the Pt electrode was the auxiliary electrode.
  • the steel plate was sampled and a sample with an exposed area of 1 cm was used as the working electrode.
  • the artificial seawater solution (Composition shown in Table 4) The sample was subjected to anodic polarization at a constant potential of -300mV, and the changes in polarization current and the corrosion current density after stabilization were recorded.
  • Figure 4 shows the -300mV (vs.Ag) of the steel plate prepared in Example 1.
  • This method can be realized by the upper and lower limits of the interval values of the process parameters (such as temperature, time, etc.) and the interval values of the present invention, and the embodiments will not be listed one by one here.

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Abstract

本发明涉及一种80mm厚690MPa级超高强韧海工钢板及其制备方法，其质量百分比化学成分为：C：0.08％～0.10％，Si：0.20％～0.30％，Mn：1.10％～1.25％，P≤0.007％，S≤0.002％，Nb：0.020％～0.030％，Ti：0.010％～0.020％，V：0.030％～0.045％，Cr：0.40％～0.60％，Ni：1.40％～1.50％，Cu：0.15％～0.25％，Mo：0.25％～0.35％，Als：0.015％～0.045％，并控制Pcm≤0.33％，Ceq≤0.64％，其余为Fe和不可避免的杂质元素。本发明的80mm690MPa级超高强韧海工钢板，性能指标全部符合中国船级社EH690钢的认证要求，-300mV（相对Ag/AgCl参比电极）饱和腐蚀电流密度≤1.90mA/cm 2，腐蚀活性夹杂物密度≤9个/mm 2。产品具有高强韧、耐低温、耐腐蚀等特性。

Description

一种80mm厚690MPa级超高强韧海工钢板及其制备方法
相关申请：
本申请要求名称为“一种80mm厚690MPa级超高强韧海工钢板及其制备方法”、于2022年6月29日提交的中国专利申请2022107478038的优先权，在此通过引用包括该件申请。
技术领域
本发明属于超高强海工钢生产技术领域，具体涉及一种80mm特厚规格690MPa级超高强韧海工钢板及其制备方法。
背景技术
随着人们对海洋领域的探索不断深入，与之相配套的特厚规格船舶与海洋工程用钢及其研发与生产已成为重中之重，复杂多变的海洋服役环境要求该特厚规格海工钢需具备高强度、高韧性、易焊接、耐海水腐蚀等优异综合性能。
目前的特厚规格690MPa级钢板的制备技术中存在诸多不足。在成分设计方面，有的添加了大量合金元素增加了生产成本，有的则会给钢板的生产过程或后续的加工使用造成困难；在生产过程方面，大多存在热处理工艺流程长的问题。
中国专利CN 111304551B提出了一种超高强调质EH690特厚钢板及其制造方法，该专利中，C：0.10％～0.17％，Si：0.25％～0.45％，Mn：0.90％～1.30％，S≤0.003％，P≤0.010％，V：0.041％～0.076％；Als：0.03％～0.05％，N：0.004％～0.013％，Ni：1.40％～1.80％，Cr：0.60％～1.00％，Mo：0.30％～0.50％，Nb：0.021％～0.04％，Cu：0.43％～0.50％，Ti≤0.02％，其中添加了较多的V、Cr、Mo、Cu等元素。该专利中，在轧制后需采用淬火+亚温淬火+回火的热处理工艺。
公开号为CN110846577A的专利申请中提出了一种具有低屈强比的690MPa级中锰钢及其制造方法，成分中含4.1％～4.7％的Mn元素，而Mn元素的大量加入会给炼钢和连铸过程带来巨大困难，连铸生产极易造成事故，且中锰钢虽然低温韧性较高，但轧制出的钢板极易出现探伤不合格和边角裂纹等问题。
公开号为CN 112251670A的申请和专利CN 102965592B均提出了特厚规格690MPa级海工钢的制备方法，其化学成分中分别添加了0.001％～0.0015％和0.001％～0.003％的B来提高钢板强度，B元素的添加会使钢板的焊接裂纹倾向显著增加，不利于后续的加工。这些制备技术中，为获得所需性能，需在淬火+高温回火热处理前做一次890～920℃的正火热处理或在淬火+高温回火热处理后做一次300℃以下的低温回火热处理，不利于生产效率的提升和降成本的行业需求。
发明内容
针对现有技术存在的不足及缺陷，本发明旨在提供一种80mm 690MPa级超高强韧海工钢板及其制备方法。本发明的80mm 690MPa级超高强韧海工钢板，性能指标符合中国船级社EH690钢的认证要求；同时，-300mV(相对Ag/AgCl参比电极)饱和腐蚀电流密度≤1.90mA/cm 2，腐蚀活性夹杂物密度≤9个/mm 2。产品具有高强韧、耐低温、耐腐蚀等优异综合特性。
为了实现上述目的，本发明第一方面提供了一种80mm690MPa级超高强韧海工钢板的成分设计，采用如下技术方案：
一种80mm690MPa级超高强韧海工钢板，所述钢板中化学成分质量百分数为：C：0.08％～0.10％，Si：0.20％～0.30％，Mn：1.10％～1.25％，P≤0.007％，S≤0.002％，Nb：0.020％～0.030％，Ti：0.010％～0.020％，V：0.030％～0.045％，Cr：0.40％～0.60％，Ni：1.40％～1.50％，Cu：0.15％～0.25％，Mo：0.25％～0.35％，Als：0.015％～0.045％，其余为Fe和不可避免的杂质元素，控制Pcm≤0.33％，Ceq≤0.64％。
其中：Ceq＝C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15；
Pcm＝C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B。
在上述80mm690MPa级超高强韧海工钢板中，作为一种优选实施方式，所述不可避免的杂质元素中以质量百分比计，H≤0.0002％，O≤0.003％，N≤0.004％，B≤0.0005％，As≤0.006％，Sb≤0.010％，Sn≤0.020％，Pb≤0.010％，Bi≤0.010％。
所述80mm690MPa级超高强韧海工钢板中主要合金的作用表现如下：
Cr对于特厚规格钢板来说，可有效提高淬透性以弥补厚度带来的强度损 失，还可提高钢板的耐腐蚀性。可一旦含量过高，就会导致低熔点的Cr-Mn复合氧化物的形成，易使钢板在热加工过程中形成表面裂纹，还会恶化焊接性能。因此本发明中Cr含量控制在0.40％～0.60％。
Ni是最为明显改善特厚规格钢板低温韧性的元素，加入适当的Ni能够降低晶体的层错能，有利于位错的滑移运动，改善冲击韧性；同时，Ni可促进钢板表面形成致密的保护性锈层，提高钢板的耐腐蚀性。但是Ni含量太高不利于保证焊接性能。因此，本发明中Ni含量控制在1.40％～1.50％。
Cu可以提高钢的耐蚀性、强度，改善焊接性与机加工性等。但是Cu含量过高会增加钢板的热脆性倾向。因此，本发明的Cu含量控制在0.15％～0.25％。
Mo是提高淬透性的元素，能扩大γ相区，推迟先析铁素体形成，有效提高强度，还可显著改善特厚规格钢板厚度方向上强韧性能的稳定性。但是，Mo含量过高会恶化钢板可焊接性，因此本发明将Mo含量控制在0.25％～0.35％。
Nb能够有效起到细化晶粒的效果，也能起到析出强化的作用；但是受C的限制及加热温度的影响，含量太高的Nb无法充分固溶。因此，本发明中Nb含量控制在0.020％～0.030％。
Ti同样可以起到细化晶粒、析出强化的效果，显著改善钢板低温冲击韧性。但含量过高时易形成大颗粒TiN而失去细晶效果。因此本发明将Ti含量控制在0.010％～0.020％。
V是钢中的细化晶粒元素，也有析出强化的效果。添加量小于0.02％时效果不明显，大于0.05％时，钢的韧性与可焊接性降低。因此，本发明中V含量控制在0.030％～0.045％。
Al能够固定钢中的自由N，改善钢板、焊接HAZ的低温韧性，而且AlN的弥散析出会抑制加热过程中奥氏体晶粒长大、均匀细化奥氏体晶粒尺寸，提高冲击韧性。但过多的Al含量会导致钢的夹杂物数量增多，夹杂物尺寸变大，钢板内部质量的下降，影响钢的热加工性能、焊接性能和切削加工性能，因此，本发明将Al含量控制在0.020％～0.050％。
Ceq：控制碳当量指标有利于保证钢板的强度和可焊性，本发明控制Ceq≤0.64％。
Pcm：控制冷裂纹敏感系数有利于保证产品的焊接性能，本发明控制Pcm≤0.33％。
钢中的杂质元素，如S、P等，会增加连铸坯偏析程度，恶化钢板厚度方向组织性能均匀性。因此，S、P含量分别控制在0.005％和0.010％以下；B易在晶界富集，降低钢板的低温冲击性能和疲劳性能，还会显著增加焊接裂纹倾向，因此，控制B≤0.0005％；同时，控制其它不可避免的杂质元素As≤0.006％，Sb≤0.010％，Sn≤0.020％，Pb≤0.010％，Bi≤0.010％，H≤0.0002％，O≤0.003％，N≤0.004％。
本发明第二方面提供一种上述80mm690MPa级超高强韧海工钢板的制备方法，包括转炉冶炼、LF+RH双精炼、连铸、铸坯加热、轧制、热处理，具体为：
(1)转炉冶炼
采用KR处理后的铁水，铁水S≤0.008％；镍板、铜板、钼铁随废钢加入；采用双渣深脱磷工艺冶炼，终渣碱度控制在R＝3.0～4.0，做到初期早化渣，过程渣化好，终渣化透；采用金属锰、铌铁、钒铁、低碳铬铁、硅铁进行合金化，合金在放钢1/4时加入，在钢水出至3/4时加完；按照3-3.5kg/t钢加入铝锰铁进行脱氧。
(2)LF+RH精炼
全程底吹氩搅拌，采用铝粒、碳化钙、碳化硅调渣，用钛线调整Ti成分，用铝线调整Al成分，终渣碱度尽量控制在2.5以上，LF精炼时间≥50min，其中软吹时间≥10min。
RH精炼采用本处理模式。确保真空度在30Pa以内，纯脱气时间≥5min。RH处理结束后，喂钙铝线1-1.5m/t，软吹时间≥14min，RH冶炼时间≥50min。
(3)连铸
采用全程保护浇铸，使用包晶钢保护渣，液相线温度为1510～1520℃，过热度控制在20℃以内，所用300mm厚连铸坯拉速为0.70-0.90m/min，在扇形段铸坯凝固末端采用轻压下技术，铸坯入坑、堆垛缓冷≥72h。
(4)铸坯加热
铸坯冷装装炉；采用多阶段加热升温方式，均热段温度1190-1240℃，均 热时间≥60min，出钢温度1200-1230℃，加热升温的总时间为290-310min，一方面保证铸坯烧匀烧透，同时又防止奥氏体晶粒过分长大；在对所述热铸坯进行轧制处理之前，进行高压水除磷处理。
(5)轧制
轧制过程为粗轧、精轧两阶段轧制。粗轧为再结晶轧制，粗轧道次≤5道，并保证至少2道次的压下率(单道次厚度压下量/入口厚度，下同)≥19％，以通过大压下率使奥氏体晶粒充分细化，为提高厚规格钢板强韧性能提供组织保证。粗轧后中间坯厚度120-130mm。精轧为未再结晶轧制，精轧开轧温度为835-865℃，精轧轧制道次≤7道，优选地，所述精轧轧制道次为5道，以充分利用道次间的形变累积效应和形变奥氏体晶内缺陷诱发的强制相变机制，促使奥氏体晶粒内部出现大量变形带、孪晶和位错，为铁素体相变形核创造条件，使钢板强韧性提高。控制粗轧后所得到的中间坯厚度，以合理分配粗轧和精轧的压下量，提高钢板性能，尤其是心部冲击韧性及厚度方向性能的均匀性。
轧制结束后通过控制冷却工艺，以增加铁素体形核率，并形成细小弥散的析出相，进一步提高钢板的强韧性。开冷温度800～820℃，终冷温度550～590℃，冷却速度控制在6～10℃/s。之后，将钢板移入缓冷坑或进行堆垛缓冷，以保证相变过程的充分进行并提高厚规格钢板的组织均匀性，缓冷时间≥48h。
(6)热处理
采用淬火+高温回火的热处理方式。
根据成分设计，本发明钢板的Ac3温度约为850℃，为确保获得细而均匀的奥氏体晶粒，以便在淬火后获得细小的马氏体组织，并降低淬火组织中低硬度铁素体相的含量，淬火加热温度应在Ac3以上30～50℃。又考虑到成分中含有Nb、V、Ti等强碳化物形成元素，可使奥氏体晶粒粗化温度升高，故将淬火温度设为920±5℃，以加速合金碳化物的溶解，增加过冷奥氏体的稳定性，提高钢的淬透性。加热时间1.3～1.6min/mm×板厚，保温时间30±3min。钢板加热保温结束后进入淬火机进行淬火处理。本发明使用的是东北大学设计的超宽整体狭缝式淬火机，其冷却水系统的高压喷水系统包括2组狭缝喷嘴和4组高密Ⅰ型喷嘴，长度3640mm，低压喷水系统包括18组高密Ⅱ型喷嘴，长度12600mm。高压段水压0.7～0.9bar，低压段水压0.3～0.4bar。按照“低辊速+大水量淬火”原 则，淬火机辊道速度1.6-1.8m/min，高压段水量5376-6067m 3/h，低压段水量3499-3888m 3/h；优选的工艺方案为，淬火机辊道速度1.6m/min，高压段水量5376m 3/h，低压段水量3888m 3/h；淬火机辊道速度1.8m/min，高压段水量6067m 3/h，低压段水量3499m 3/h。上喷嘴水量与下喷嘴水量之比约为1∶1.4，以保证钢板在淬火过程的对称、均匀。这样，通过高压段的冷却，使钢板充分淬透完成所有相转变，低压段则进一步带走从钢板内部传导到表面的热量以防止余热回火，使钢板温度最终降低到室温。
高温回火，可消除快冷淬火后钢板复杂的内应力，并使钢板具备优异的综合力学性能。本发明中回火加热温度600±5℃，加热时间2～2.5min/mm*板厚，保温时间30±3min。钢板出炉后在冷床吹冷风空冷至室温，要避免出炉后短时间内便堆垛存放，以防止钢板出现高温回火脆性。
这样，就获得了80mm690MPa级超高强韧海工钢板，主要性能指标：屈服强度≥690MPa，抗拉强度770～940MPa，断后伸长率≥16％，-40℃心部横向冲击功≥100J，-40℃CTOD≥0.15mm，-300mV(相对Ag/AgCl参比电极)饱和腐蚀电流密度≤1.90mA/cm 2，腐蚀活性夹杂物密度≤9个/mm 2。
与现有技术相比，本发明的优势在于：
(1)良好的性能均匀性。本发明通过对炼钢过程中成分、纯净度以及气体含量的控制，提供了高质量铸坯原料；科学设计加热、轧制、轧后控冷工艺，通过粗轧阶段大压下、合理两阶段压下量分配等措施，使变形渗透到钢板心部；优化热处理工艺，在整个厚度截面获得高强韧性组织，力学性能、横纵向冲击、时效冲击及冷弯等性能优异，且厚度方向性能均匀，完全满足船级社EH690钢的认证要求。
(2)低成本、高生产效率。优化成分设计，利用合理的控轧控冷工艺，将塑性变形和轧后冷却与固态相变相结合，充分发挥固溶强化、沉淀强化和细晶强化的作用，保证了合金元素的效果充分发挥；通过最优化淬火机辊道速度、高压低压段水量和上下水比设计，提高了厚规格钢板的热处理效果，经过淬火和高温回火处理后，无需再经过其他热处理过程即可获得性能优异的钢板，缩短了生产流程，降低了生产成本。
(3)耐腐蚀性能优异。本发明利用高洁净钢水冶炼技术、高渗透轧制技术 以及最优化热处理工艺，获得低夹杂、高均质的耐蚀性良好的组织，使钢板基体自身腐蚀电位大大提高；同时，Cr+Cu+Ni合金元素的添加，可有效促使钢板表面形成致密、附着性好的保护性锈层，阻碍H 2O、O 2、Cl -等腐蚀介质向钢材基体渗透，保证了产品在海洋强腐蚀环境下的服役安全性。
附图说明
图1为本发明实施例1制得钢板近表面500x金相组织；
图2为本发明实施例1制得钢板厚度1/4位置500x金相组织；
图3为本发明实施例1制得钢板厚度1/2位置500x金相组织；
图4为本发明实施例1制得钢板的-300mV(vs.Ag/AgCl)恒电位极化曲线；
图5为本发明实施例1制得钢板50x视场下的腐蚀活性夹杂物情况。
具体实施方式
下面以附图和具体实施方式对本发明作进一步详细的说明。
实施例1：
按表1所示的化学成分，按照上述冶炼工艺，通过转炉冶炼、LF+RH双精炼获得高洁净钢水，浇铸得到300mm厚连铸坯。对铸坯进行加热，出钢温度1210℃，在炉时间300min，粗轧5道次(第5道空过)，第3、4道次压下率分别为19.3％、23.7％，粗轧结束后中间坯厚度130mm；待温至845℃开始精轧阶段，精轧7道次(第7道空过)；以约8℃/s的速度进行控冷，开冷温度815℃，终冷温度590℃。轧后在缓冷坑缓冷48h以上。淬火温度加热至920℃，保温30min，淬火机辊道速度1.8m/min，高压段水量6067m 3/h，低压段水量3499m 3/h，上喷嘴水量与下喷嘴水量之比为1∶1.4。回火加热温度600℃，保温30min。由图1-图3可以看到，近表面组织以回火索氏体为主，随着往心部发展，弥散分布的粒状贝氏体以及铁素体、珠光体含量逐渐增多。按照中国船级社《材料与焊接规范》(2021)中的试验方法和要求进行检验，主要拉伸性能和冲击性能指标见表2，耐腐蚀性能指标见表3。
实施例2：
按表1所示的化学成分，按照上述冶炼工艺，通过转炉冶炼、LF+RH双精 炼获得高洁净钢水，浇铸得到300mm厚连铸坯。对铸坯进行加热，连铸坯加热出钢温度1230℃，在炉时间290min，粗轧5道次，第4、5道次压下率分别为19.1％、22.3％，粗轧结束后中间坯厚度120mm；待温至860℃开始精轧阶段，精轧5道次；以约10℃/s的速度进行控冷，开冷温度803℃，终冷温度559℃。轧后在缓冷坑缓冷48h以上。淬火温度加热至920℃，保温30min，淬火机辊道速度1.6m/min，高压段水量5376m 3/h，低压段水量3888m 3/h，上喷嘴水量与下喷嘴水量之比为1∶1.4。回火加热温度600℃，保温30min。
对比例：
为了说明淬火机参数对钢板性能的影响，本发明将淬火机调整过程中的一种实施方式作为对比例进行说明。对比例冶炼、浇铸实施方式同实施例2。对铸坯进行加热，连铸坯加热出钢温度1230℃，在炉时间290min，粗轧5道次，第4、5道次压下率分别为20.0％、21.6％，粗轧结束后中间坯厚度120mm；待温至850℃开始精轧阶段，精轧5道次；以约10℃/s的速度进行控冷，开冷温度805℃，终冷温度562℃。轧后在缓冷坑缓冷48h以上。淬火温度加热至920℃，保温30min，淬火机辊道速度2.0m/min，高压段水量6255m 3/h，低压段水量3287m 3/h，上喷嘴水量与下喷嘴水量之比为1∶1.4。回火加热温度600℃，保温30min。
表2为实施例和对比例所得钢板的拉伸性能和冲击性能。按照本发明的方法制备的钢板屈服强度≥690MPa，抗拉强度770～940MPa，断后伸长率≥16％；-40℃横向冲击功≥100J，且厚度方向性能均匀性良好。而对比例的强度和韧性明显低于实施例，尤其是厚度1/4和心部冲击性能无法达到E690钢的性能要求。
表3为实施例和对比例所得钢板的耐腐蚀性能指标。饱和腐蚀电流密度使用Autolab电化学工作站测量，使用三电极体系，Ag/AgCl电极为参比电极，Pt电极为辅助电极，对钢板取样制作暴露面积1cm 2的试样作为工作电极，在人工海水溶液(成分见表4)中以-300mV恒电位下试样进行阳极极化，记录极化电流变化及其稳定后的腐蚀电流密度，图4为实施例1制得钢板的-300mV(vs.Ag/AgCl)恒电位极化曲线。测定腐蚀活性夹杂物密度时，对钢板取样制成10mm*10mm*5mm的试样，抛光后浸泡于人工海水中20min。取出后酒精冲洗，冷风干燥，置于50x光镜下连续拍摄若干张照片并计算腐蚀活性夹杂物密度， 图5为实施例1制得钢板50x视场下的腐蚀活性夹杂物情况。
表1本发明实施例和对比例钢板的化学成分(wt％)
Figure PCTCN2022139834-appb-000001
表2本发明实施例和对比例钢板的性能
Figure PCTCN2022139834-appb-000002
表3本发明实施例钢板的耐腐蚀性能指标
Figure PCTCN2022139834-appb-000003
Figure PCTCN2022139834-appb-000004
表4人工海水成分
Figure PCTCN2022139834-appb-000005
本发明的工艺参数(如温度、时间等)区间上下限取值以及区间值都能实现本法，在此不一一列举实施例。
本发明未详细说明的内容均可采用本领域的常规技术知识。
最后所应说明的是，以上实施例仅用以说明本发明的技术方案而非限制。尽管参照实施例对本发明进行了详细说明，本领域的普通技术人员应该理解，对本发明的技术方案进行修改或者等同替换，都不脱离本发明技术方案的精神和范围，其均应涵盖在本发明的权利要求范围当中。

Claims (10)

  1. 一种80mm厚690MPa级超高强韧海工钢板，其特征在于，该钢板的化学成分按质量百分比计为：C：0.08％～0.10％，Si：0.20％～0.30％，Mn：1.10％～1.25％，P≤0.007％，S≤0.002％，Nb：0.020％～0.030％，Ti：0.010％～0.020％，V：0.030％～0.045％，Cr：0.40％～0.60％，Ni：1.40％～1.50％，Cu：0.15％～0.25％，Mo：0.25％～0.35％，Als：0.015％～0.045％，并控制Pcm≤0.33％，Ceq≤0.64％，其余为Fe和不可避免的杂质元素。
  2. 根据权利要求1所述的80mm厚690MPa级超高强韧海工钢板，其特征在于，所述不可避免的杂质元素中各组分的质量百分比含量为：H≤0.0002％，O≤0.003％，N≤0.004％，B≤0.0005％，As≤0.006％，Sb≤0.010％，Sn≤0.020％，Pb≤0.010％，Bi≤0.010％。
  3. 根据权利要求1或2所述的80mm厚690MPa级超高强韧海工钢板，其特征在于，所述超高强韧海工钢板的主要性能指标：屈服强度≥690MPa，抗拉强度770～940MPa，断后伸长率≥16％，-40℃心部横向冲击功≥100J，-40℃CTOD≥0.15mm，相对Ag/AgCl参比电极-300mV饱和腐蚀电流密度≤1.90mA/cm 2，腐蚀活性夹杂物密度≤9个/mm 2。
  4. 一种权利要求1-3中任一项所述的80mm厚690MPa级超高强韧海工钢板的制备方法，所述制备方法包括如下步骤：转炉冶炼、LF+RH双精炼、连铸、铸坯加热、轧制、热处理。
  5. 根据权利要求4所述的制备方法，其特征在于，所述转炉冶炼中，采用KR处理后的铁水，铁水S≤0.008％，镍板、铜板、钼铁随废钢加入，采用双渣深脱磷工艺冶炼，使用金属锰、铌铁、钒铁、低碳铬铁、硅铁进行合金化，按照3-3.5kg/t钢加入铝锰铁进行脱氧。
  6. 根据权利要求4所述的制备方法，其特征在于，所述LF+RH双精炼中，LF精炼全程底吹氩，精炼时间≥50min，其中软吹时间10-15min；RH精炼确保真空度在30Pa以内，纯脱气时间≥5min，RH处理结束后，喂钙铝线1-1.5m/t，软吹时间15-20min，RH冶炼时间≥50min。
  7. 根据权利要求4所述的制备方法，其特征在于，所述连铸中，采用全程保护浇铸，过热度控制在20℃以内，所用300mm厚连铸坯拉速为 0.70-0.90m/min，所得铸坯缓冷72小时以上。
  8. 根据权利要求4所述的制备方法，其特征在于，所述铸坯加热中，采用多阶段加热升温方式，均热段温度1190-1240℃，均热时间≥60min，出钢温度1200-1230℃，加热升温的总时间为290-310min。
  9. 根据权利要求4所述的制备方法，其特征在于，所述轧制中，包括粗轧、精轧两阶段轧制；粗轧为再结晶轧制，粗轧道次≤5道，并保证至少2道次的压下率≥19％，粗轧后中间坯厚度120-130mm；精轧为未再结晶轧制，精轧开轧温度为835-865℃，精轧轧制道次≤7道，轧后的快冷过程开冷温度800～820℃，终冷温度550～590℃，冷却速度6～10℃/s。
  10. 根据权利要求4所述的制备方法，其特征在于，所述热处理中，采用淬火+高温回火工艺；淬火温度920±5℃，加热时间1.3～1.6min/mm×板厚，保温时间30±3min；淬火机高压段水压0.7～0.9bar，低压段水压0.3～0.4bar，辊道速度1.6-1.8m/min，高压段水量5376-6067m 3/h，低压段水量3499-3888m 3/h；上喷嘴水量与下喷嘴水量之比约为1∶1.4，回火加热温度600±5℃，加热时间2～2.5min/mm*板厚，保温时间30±3min，出炉后空冷。
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CN103014541A (zh) * 2012-12-21 2013-04-03 首钢总公司 一种690MPa级厚规格海洋工程用钢及其制造方法
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CN110846577A (zh) 2019-11-20 2020-02-28 南京钢铁股份有限公司 690MPa级高强度低屈强比中锰钢中厚钢及制造方法
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CN115094322A (zh) * 2022-06-29 2022-09-23 山东钢铁股份有限公司 一种80mm厚690MPa级超高强韧海工钢板及其制备方法

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