WO2022214107A1 - 一种高韧性的低合金高强度钢的轧制方法 - Google Patents

一种高韧性的低合金高强度钢的轧制方法 Download PDF

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WO2022214107A1
WO2022214107A1 PCT/CN2022/092306 CN2022092306W WO2022214107A1 WO 2022214107 A1 WO2022214107 A1 WO 2022214107A1 CN 2022092306 W CN2022092306 W CN 2022092306W WO 2022214107 A1 WO2022214107 A1 WO 2022214107A1
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rolling
cooling
strength steel
water
toughness low
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PCT/CN2022/092306
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English (en)
French (fr)
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李小龙
时涛
周敦世
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大冶特殊钢有限公司
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Priority to KR1020237038961A priority Critical patent/KR20240004507A/ko
Priority to EP22784173.1A priority patent/EP4338862A1/en
Priority to JP2023569599A priority patent/JP2024518471A/ja
Publication of WO2022214107A1 publication Critical patent/WO2022214107A1/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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C21D9/0075—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rods of limited length
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • B21B37/76—Cooling control on the run-out table
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0203—Cooling
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/60—Aqueous agents
    • 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
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
    • 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
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0062—Heat-treating apparatus with a cooling or quenching zone
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • 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
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite

Definitions

  • the invention relates to the field of steel rolling, in particular to a rolling method of high-toughness low-alloy high-strength steel.
  • low-alloy high-strength steel has been widely used in aerospace, shipbuilding and other high-end fields because of its high strength, good plasticity and toughness. , especially in infrastructure such as oil pipelines, bridges, large buildings, vehicles, containers and machinery, chemical, medical, light industrial equipment and other engineering fields are also widely used. Low-alloy high-strength steels are widely used in machinery and equipment, vehicles and pipe making due to their high strength, superior formability and stable overall performance.
  • the ways to improve the strength of steel materials include solid solution strengthening, dislocation strengthening, grain refinement strengthening, and precipitation strengthening of second-phase particles.
  • toughness With the grain refinement and the increase of crack propagation resistance, the fatigue strength of the steel increases, the toughness increases, and the temperature of the brittle turning point decreases. Fine-grained steel has good strength and toughness, and is widely used in automobiles, ships, bridges and construction machinery.
  • the strength and toughness of low-alloy high-strength steel cannot be achieved simultaneously.
  • only the rolling method of steel plates and strips is involved, and the rolling method of bar and round steel is not involved, and the rolling process needs to be off-line.
  • the normalizing step has a high production cost, which is not conducive to energy saving and cost reduction and green manufacturing.
  • the purpose of the present invention is to provide a rolling method of high-toughness low-alloy high-strength steel, formulate reasonable production process control through microalloying elements and controlled rolling and controlled cooling process technology, and successfully developed A rolling method for producing a high-toughness low-alloy high-strength steel, in the manufacturing process of the product, the off-line normalizing step is removed, the technological manufacturing process is reduced, and the manufacturing cost is saved; the low-alloy high-strength steel manufactured by the process and method Steel, the metallographic structure is fine ferrite plus pearlite, the tensile strength is greater than 630MPa, the yield strength is greater than 500MPa, the grain size after rolling is fine and uniform, the grain size is above 9.0, and the comprehensive mechanical properties far exceed conventional rolling. manufacturing process.
  • the present invention provides the following technical solutions:
  • a rolling method of high-toughness low-alloy high-strength steel comprises the following steps in sequence: heating, descaling, rough rolling, continuous rolling, first cooling through water penetration, finishing rolling, and second penetration Water cooling and cooling bed cooling.
  • the chemical components and contents of the continuous casting billet of the high-toughness, low-alloy and high-strength steel are: C ⁇ 0.20; Si ⁇ 0.60; Mn1.00 ⁇ 1.70; Cr ⁇ 0.30 ; P ⁇ 0.020; S ⁇ 0.020; V0.05 ⁇ 0.10; Al ⁇ 0.03; N ⁇ 0.025; the rest are Fe and inevitable impurities.
  • the heating step is divided into four stages, which are preheating, first stage heating, second stage heating and soaking stage in sequence.
  • the temperature of the preheating section is ⁇ 750°C.
  • the temperature of the first stage of heating is 900-1050°C.
  • the temperature of the second-stage heating is 1050-1150°C.
  • the temperature of the soaking zone is 1150-1210°C.
  • the total heating time of the heating step is 3-5 hours.
  • the soaking time of the soaking section is 30-80 minutes.
  • the heating step is performed in a four-stage walking heating furnace.
  • the inlet temperature of rough rolling is 950-1050° C.
  • the rough rolling passes are 5-7 passes
  • the number of rough rolling mills set in the rough rolling step is six.
  • the continuous rolling step includes intermediate rolling and pre-finishing rolling.
  • the inlet temperature of the intermediate rolling is 900-1000°C.
  • the number of intermediate rolling mills set in the intermediate rolling is 6, and the intermediate rolling passes are 5 to 7 passes.
  • the intermediate rolling passes are 6 passes.
  • the outlet temperature of the prefinishing rolling is 850-950°C.
  • the number of pre-finishing rolling mills set in the pre-finishing rolling is 4, and the number of pre-finishing rolling passes is 3 to 5 passes, preferably In particular, the pre-finishing rolling passes are 4 passes.
  • the incoming material after the continuous rolling step is subjected to water cooling for the first time, wherein the water cooling rate is 25 ⁇ 50°C/s, the water pressure is 0.2 ⁇ 0.6MPa.
  • the entry rolling temperature of the finishing rolling is 800-850°C.
  • a reducing and sizing mill is used for finishing rolling.
  • the reducing and sizing unit is a three-roll reducing and sizing unit.
  • the steel after the finishing rolling step is subjected to water cooling for the second time, wherein the water cooling rate is 25 ⁇ 100°C/s, the water pressure is 0.2 ⁇ 0.6MPa.
  • the rolling method of the above-mentioned high-toughness low-alloy high-strength steel adopts high-pressure water descaling for the purpose of removing scale, and the water pressure of the high-pressure water is 15 ⁇ 20MPa.
  • the water pressure of the high-pressure water is 17-20 MPa.
  • the above-mentioned rolling method of high-toughness low-alloy high-strength steel obtains a high-toughness low-alloy high-strength steel bar through the rolling method, and the specification of the steel bar is
  • the cooling-bed cooling refers to air-cooling the steel obtained after the second water penetration cooling in the cooling-bed.
  • the on-line TMCP process is used to control the precipitation process of nitrides to form ferrite and pearlite structures.
  • the grains are refined again. It can improve its plasticity and impact toughness, and achieve high-strength control of mechanical properties.
  • the actual grain size of the low-alloy high-strength steel can be refined by this rolling method, the obtained low-alloy high-strength steel has excellent comprehensive properties, the metallographic structure is fine ferrite plus pearlite, the tensile strength is greater than 630MPa, yield The strength is greater than 500MPa, the grain size after rolling is fine and uniform, the grain size is above 9.0, the impact energy at -20°C is greater than 100J, and the impact energy at -40°C is greater than 80J, and its comprehensive mechanical properties far exceed the conventional rolling process;
  • Figure 1 shows the rolling of Comparative Example 2 The metallographic structure obtained by the specification
  • Figure 2 shows the rolling of Comparative Example 2 Grain size obtained by specification (7.5 grade);
  • Fig. 3 is the rolling of Example 2 of the present invention
  • the metallographic structure obtained by the specification;
  • Fig. 4 is the rolling of Example 2 of the present invention Grain size obtained by specification (9.0 grade).
  • the rolling method disclosed in the present invention is designed according to the continuous rolling process parameters, through the combination of the solid phase transformation and the plastic deformation of the rolling principle, using a four-stage stepping heating furnace heating process system and a rolling reduction system to plastically form materials, and through roughening
  • the rolling, intermediate rolling and finishing rolling deformation systems are used to form products, and finally the solid-state phase transformation of the metal is controlled by the controlled cooling process, so as to obtain the high-quality microstructure and excellent microstructure and mechanical properties of the required products.
  • a rolling method of high-toughness low-alloy high-strength steel comprises the following steps in sequence: heating, descaling, rough rolling, continuous rolling, first cooling through water penetration, finishing rolling, and second penetration Water cooling and cooling bed air cooling; using converter continuous casting billet as raw material, according to mass percentage, the chemical components and contents of continuous casting billet are: C ⁇ 0.20; Si ⁇ 0.60; Mn1.00 ⁇ 1.70; Cr ⁇ 0.30; P ⁇ 0.020; S ⁇ 0.020; V0.05 ⁇ 0.10; Al ⁇ 0.03; N ⁇ 0.025; the balance is Fe and inevitable impurities.
  • grain refinement can improve plasticity and toughness is that fine grains provide better conditions for the occurrence and expansion of plastic deformation. All the factors that reduce the austenite to ferrite transformation temperature Ar3 have the tendency of grain refinement.
  • the impact toughness is improved by adding the content of microalloying element V, and at the same time, the microalloying element vanadium V dissolves into ferrite and has a strengthening effect, forming stable carbides and refining grains.
  • the rolling method includes the following steps in sequence:
  • the heating step is carried out in a four-stage walking heating furnace; the heating step is divided into four stages, which are preheating, first stage heating, second stage heating and soaking stage.
  • the temperature of the preheating section is less than or equal to 750°C (such as 600°C, 650°C, 665°C, 700°C, 750°C and the interval or interval point between any two temperatures); that is, if the furnace temperature exceeds 750°C, Then, the heat transfer rate of the billet may be too fast, and the temperature difference between the billet and the heating furnace may be too large, which may lead to cracks on the surface of the cast billet or the final rolled product.
  • 750°C such as 600°C, 650°C, 665°C, 700°C, 750°C and the interval or interval point between any two temperatures
  • the temperature for a heating stage is 900-1050°C (such as 900°C, 950°C, 980°C, 1000°C, 1010°C, 1050°C, and the interval or interval point between any two temperatures).
  • the temperature of the second heating stage is 1050-1150 °C (such as 1050 °C, 1080 °C, 1100 °C, 1110 °C, 1130 °C, 1150 °C, and the interval or interval point between any two temperatures).
  • the main functions of heating the first stage and the second stage are: reducing energy consumption and reducing oxidation and burning loss of steel billets.
  • the temperature of the soaking section is 1150 to 1210 °C (such as 1150 °C, 1160 °C, 1165 °C, 1170 °C, 1185 °C, 1190 °C, 1205 °C, 1210 °C and any two of them.
  • the interval or interval between the temperatures is 1150 to 1210 °C (such as 1150 °C, 1160 °C, 1165 °C, 1170 °C, 1185 °C, 1190 °C, 1205 °C, 1210 °C and any two of them.
  • the interval or interval between the temperatures is 1150 to 1210 °C (such as 1150 °C, 1160 °C, 1165 °C, 1170 °C, 1185 °C, 1190 °C, 1205 °C, 1210 °C and any two of them.
  • the interval or interval between the temperatures is 1150 to 1210 °C (such as 1150 °C, 1160 °C, 11
  • the total heating time of the heating step is 3-5h (such as 3.5h, 4h, 4.5h, 4.8h and the time point between any two time periods); the soaking time of the soaking section is 30- 80min (such as 30min, 35min, 40min, 45min, 50min, 55min, 60min, 70min, 75min, 80min and the time point between any two time periods).
  • the heating step achieves the following four goals: first, omitting the off-line normalizing step can reduce energy consumption and save costs; second, the four-stage heating process can reduce the oxidation and burning loss of the billet; third, reduce the decarburization of the billet; fourth, Reduce the surface cracks of the final rolled material due to too long heating time.
  • the heated billet is descaled with high-pressure water to remove iron scale, and the pressure of the high-pressure water is 15-20MPa (such as 15MPa, 16.5MPa, 17MPa, 18MPa, 20MPa and the pressure value between any two pressure values);
  • the pressure value of the high-pressure water is preferably 17 to 20 MPa.
  • the rough rolling step is preferably provided with 6 rough rolling mills; wherein the inlet temperature of rough rolling is 950 to 1050 ° C (such as 950 ° C, 980 ° C, 1000 ° C, 1020 ° C, 1035 ° C, 1050 ° C and any two temperatures between them. interval or interval point), the rough rolling pass is 5 to 7 passes; the rough rolling pass is preferably 6 passes.
  • the rough rolling step adopts the rolling method of continuous rolling, which mainly changes the surface size of the billet through plastic deformation.
  • the continuous rolling step includes intermediate rolling and pre-finishing, and the inlet temperature of the intermediate rolling is 900 to 1000 ° C (such as 905 ° C, 920 ° C, 940 ° C, 950 ° C, 970 ° C, 1000 ° C and any two temperatures between them.
  • Interval section or interval point preferably 6 intermediate rolling mills are arranged in the intermediate rolling step, and the intermediate rolling passes are 5 to 7 passes; the intermediate rolling passes are preferably 6 passes.
  • the pass design mainly adopts oval and round pass design. Through the rolling process, the shape of the blank section is close to the shape of the finished product.
  • the outlet temperature of pre-finishing rolling is 850 ⁇ 950°C (such as 855°C, 870°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C and the interval between any two of them.
  • the pre-finishing rolling step preferably 4 pre-finishing rolling mills are arranged, the pre-finishing rolling passes are 3 to 5 passes, and the pre-finishing rolling pass is preferably 4 passes.
  • the pass design mainly adopts oval and round pass design. Through the rolling process, the shape of the blank section is close to the shape of the finished product.
  • the incoming material after the continuous rolling step is cooled by water for the first time.
  • the interval section or interval point between any two temperatures wherein the cooling speed of the first water cooling is 25 ⁇ 50°C/s, and the water pressure is 0.2 ⁇ 0.6MPa.
  • the rolling material obtained in step (5) enters the reducing and sizing finishing rolling unit for rolling, and the reducing and sizing finishing rolling unit is preferably a three-roll reducing and sizing finishing rolling unit, that is, the KOCKS reducing and sizing finishing rolling unit, and the inlet opening temperature is 800 °C. ⁇ 850°C (such as 800°C, 810°C, 820°C, 824°C, 832°C, 850°C, and the interval or interval point between any two temperatures).
  • three-roll reducing and sizing unit finishing rolling can better implement low-temperature rolling, thereby improving the grain size and comprehensive mechanical properties of non-quenched and tempered steel, and providing its excellent performance for the production of non-quenched and tempered steel.
  • the steel after finishing rolling is cooled by water for the second time, and the temperature of the steel after the finishing rolling step is cooled by water for the second time at 600-700°C (such as 600°C, 625°C, 640°C, 662°C, 683°C). °C, 700°C and the interval or interval point between any two temperatures), wherein the water cooling speed is 25 ⁇ 100°C/s, and the water pressure is 0.2 ⁇ 0.6MPa.
  • the final required metallographic structure and mechanical properties of the steel can be obtained by controlling the temperature of the steel and the temperature of the steel by performing the second water cooling after finishing rolling and controlling the temperature and the water cooling speed of the second water cooling.
  • cooling bed cooling is cooling bed air cooling
  • the steel obtained after the second water penetration cooling is air-cooled in the cooling bed, and finally the finished steel is obtained.
  • steps (1) to (8) are the main steps to refine the grain size of the high carbon steel seed, and the refinement is achieved by combining the control of the heating temperature, the degree of deformation and the cooling rate.
  • the actual grain size the purpose of improving the rigidity and toughness of steel.
  • the online TMCP process (that is, the thermomechanical control process) is used to control the precipitation process of nitrides to form a uniform ferrite and pearlite structure.
  • the strength of steel can be improved, and its plasticity and impact toughness can be improved to achieve high-strength control of mechanical properties.
  • the method for rolling high-toughness, low-alloy and high-strength steel according to the present invention is unique, and adopts the combined action of trace alloy elements and the controlled rolling, controlled cooling technology of the thermomechanical control process to realize on-line control. Refine the actual grain size of the high-toughness low-alloy high-strength steel.
  • the high-toughness low-alloy high-strength steel has excellent comprehensive properties.
  • the metallographic structure is fine ferrite and pearlite.
  • the tensile strength is greater than 630MPa, and the yield strength More than 500MPa, the grain size after rolling is fine and uniform, the grain size is above 9.0, the Charpy V-type impact energy at -20°C is greater than 100J, and the Charpy V-type impact energy at -40°C is greater than 80J, and its comprehensive mechanical properties are far Extraordinary rolling method.
  • the high-toughness low-alloy high-strength steel is not subjected to off-line normalizing treatment during the manufacturing process, and its mechanical properties can also meet the requirements for use, which not only saves processing time, but also reduces costs and increases efficiency.
  • Embodiment 1 provides a kind of rolling method of high-toughness low-alloy high-strength steel, and the required finished product specification is
  • the 300 ⁇ 400mm section continuous casting billet is selected; among them, the chemical components in the continuous casting billet are in mass percentage, as shown in Table 2, and the total mass fraction is 100%; including the following steps:
  • (1) Heating After cutting the section continuous casting billet, it is put into a four-stage walking furnace for heating by cold conveying.
  • the temperature of the preheating section is 685 °C
  • the temperature of the heating section is 1005 °C
  • the temperature of the heating section is 1086 °C.
  • the temperature of the soaking section is 1175°C; the total heating time in this heating step is 3.8h, and the soaking time of the soaking section is 43min.
  • Rough rolling The descaled billet is sent to a high-rigidity rough rolling mill (6 stands) for rough rolling to obtain a rough rolled billet; the rough rolling inlet temperature is 1015°C, and the rough rolling passes are 6 passes.
  • step (3) the rough-rolled steel billet obtained in step (3) is sent to the continuous rolling unit, the intermediate rolling inlet temperature is 925 ° C, the intermediate rolling pass is 6 passes, and the outlet temperature of the pre-finishing rolled steel billet is 910 ° C, The pre-finishing billet passes are 4 passes.
  • the first water penetration cooling the rolled material after prefinishing is subjected to the first water penetration cooling; the temperature is cooled to 790°C; the water cooling speed is 40°C/s, and the water pressure is 0.5MPa.
  • Second water penetration cooling the finished rolling material is subjected to water cooling for the second time; the temperature is cooled to 685°C; the water cooling rate is 75°C/s, and the water pressure is 0.6MPa.
  • cooling bed cooling (cooling bed air cooling): the specification obtained in step (7) is The steel bar is air-cooled in the cooling bed, and finally the finished steel bar is obtained.
  • the high-toughness, low-alloy and high-strength steel obtained in Example 1 has a uniform ferrite and pearlite in the hot-rolled state, and the actual grain size is 9.0.
  • the mechanical properties of the steel product are shown in Table 3.
  • the high-toughness low-alloy high-strength steel obtained in Example 1 has uniform ferrite and pearlite in hot-rolled structure, and the actual grain size is 9.0. It can be seen from Table 3 that its steel product has excellent mechanical properties.
  • Embodiment 2 provides a kind of rolling method of high-toughness low-alloy high-strength steel, and the required finished product specification is A 300 ⁇ 400mm section continuous casting billet is selected; among them, the chemical components in the continuous casting billet are in mass percentage, as shown in Table 2, and the total mass fraction is 100%; the rolling method goes through the following steps in sequence: (1) heating, (2) descaling, (3) rough rolling, (4) continuous rolling, (5) first water penetration cooling, (6) finishing rolling, (7) second water penetration cooling and (8) cooling bed cooling (Cooling bed air cooling), the processing steps of Example 2 are the same as those of Example 1, the processing parameters of the specific steps are shown in Table 1, and the mechanical properties of the steel products are shown in Table 3.
  • the high-toughness low-alloy high-strength steel obtained in Example 2 has a hot-rolled microstructure of uniform ferrite and pearlite, as shown in FIG. 3 ; the actual grain size is 9.0, as shown in FIG. 4 . It can be seen from Table 3 that the mechanical properties of its steel products are superior.
  • Embodiment 3 provides a kind of rolling method of high-toughness low-alloy high-strength steel, and the required finished product specification is A 300 ⁇ 400mm section continuous casting billet is selected; among them, the chemical components in the continuous casting billet are in mass percentage, as shown in Table 2, and the total mass fraction is 100%; the rolling method goes through the following steps in sequence: (1) heating, (2) descaling, (3) rough rolling, (4) continuous rolling, (5) first water penetration cooling, (6) finishing rolling, (7) second water penetration cooling and (8) cooling bed cooling (Cooling bed air cooling), the processing steps of Example 3 are the same as those of Example 1, the processing parameters of the specific steps are shown in Table 1, and the mechanical properties of the steel products are shown in Table 3.
  • the high-toughness low-alloy high-strength steel obtained in Example 3 has uniform ferrite and pearlite in hot-rolled state, and the actual grain size is 9.0. It can be seen from Table 3 that its steel product has excellent mechanical properties.
  • Example 1 Example 2
  • Example 3 Yield Strength (MPa) ⁇ 420 523 525 525
  • Tensile strength (MPa) ⁇ 520 648 654 654 extend(%) ⁇ 19 32 28 28 -20°C Charpy V-type impact energy (J) ⁇ 47 135 132 132 -40°C Charpy V-type impact energy (J) ⁇ 31 103 105 105
  • Embodiments 4-7 provide a method for rolling high-toughness low-alloy high-strength steel.
  • the rolling method sequentially goes through the following steps: (1) heating, (2) descaling, (3) rough rolling, (4) ) continuous rolling, (5) cooling by water penetration for the first time, (6) finishing rolling, (7) cooling by water penetration for the second time and (8) cooling bed cooling (air cooling bed cooling), the processing steps of embodiment 4-7 and the mechanical parameters are the same as in Example 1; the content of each chemical component in the continuous casting slab used in Examples 4-7 is in mass percentage, as shown in Table 4, and the mass fraction is 100% in total.
  • Example 4 Example 5
  • Example 6 Example 7 Yield Strength (MPa) ⁇ 420 530 537 528 525
  • Tensile strength (MPa) ⁇ 520 658 649 660 652 extend(%) ⁇ 19 30 29 31 30 -20°C Charpy V-type impact energy (J) ⁇ 47 129 135 130 132 -40°C Charpy V-type impact energy (J) ⁇ 31 104 108 110 106
  • the required finished product specifications are The 300 ⁇ 400mm section continuous casting billet is selected; the chemical components and contents of the continuous casting billet are: C0.45; Si 0.28; Mn1.46; Cr 0.16; V0.06; N0.010; Al 0.020; P ⁇ 0.020; S ⁇ 0.020; the rest are Fe and inevitable impurities.
  • the processing steps and parameters of the alloy steel are shown in Table 7.
  • the required finished product specifications are The 300 ⁇ 400mm section continuous casting billet is selected; the chemical components and contents in the continuous casting billet are: C0.16; Si 0.30; Mn 0.8; Cr 0.15; V0.07; N0.012; Al 0.020; P ⁇ 0.020; S ⁇ 0.020, the balance is Fe and inevitable impurities.
  • the processing steps and parameters of the alloy steel are shown in Table 7.
  • the required finished product specifications are The 300 ⁇ 400mm section continuous casting billet is selected; the chemical components and contents in the continuous casting billet are: C0.16; Si 0.30; Mn1.40; Cr 0.15; N0.011; Al 0.022; P ⁇ 0.020; S ⁇ 0.020; The amount is Fe and inevitable impurities.
  • the processing steps and parameters of the alloy steel are shown in Table 7.
  • the required finished product specifications are The 300 ⁇ 400mm section continuous casting billet is selected; the chemical components and contents in the continuous casting billet are: C0.16; Si 0.32; Mn1.47; Cr 0.15; V0.06; N0.040; Al 0.020; P ⁇ 0.020; S ⁇ 0.020; the balance is Fe and inevitable impurities.
  • the processing steps and parameters of the alloy steel are shown in Table 7.
  • Table 6 The chemical composition of the continuous casting slab selected for the comparative examples 1-4

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Abstract

一种高韧性的低合金高强度钢的轧制方法，该轧制方法依次包括如下步骤：加热、除鳞、粗轧、连轧、第一次穿水冷却、精轧、第二次穿水冷却和冷床空冷；以转炉连铸坯为原料，按照质量百分比，连铸坯中各化学成分和含量为：C≤0.20；Si≤0.60；Mn1.00～1.70；Cr≤0.30；P≤0.020；S≤0.020；V0.05～0.10；Al≤0.03；N≤0.025；余量为Fe和不可避免的杂质。采用该轧制方法可以细化低合金高强度钢的实际晶粒度，低合金高强度钢的综合性能优异，金相组织为细小铁素体加珠光体，晶粒度达9.0级以上，-20℃冲击功大于100J，-40℃冲击功大于80J。

Description

一种高韧性的低合金高强度钢的轧制方法 技术领域
本发明涉及钢材轧制领域，具体涉及一种高韧性的低合金高强度钢的轧制方法。
背景技术
随着社会的经济发展和科技的进步，钢铁材料已广泛应用于各个领域，其中低合金高强度钢，因具有高的强度、良好的塑性和韧性，已经广泛用于航空航天、船舶等高端领域，特别是在石油管线、桥梁、大型建筑物等基础设施和车辆、容器及机械、化工、医疗、轻工设备等工程领域也得到广泛应用。低合金高强度钢因强度高、成型性优越和综合性能稳定，被广泛应用于机械设备、车辆和制管等领域。
目前，提高钢铁材料强度的途径有固溶强化、位错强化、细晶强化和第二相粒子的析出强化等；其中细晶强化效果最为明显，细晶强化后的钢材具有较好的强度与韧性。随着晶粒细化、裂纹扩展阻力提高，钢的疲劳强度增加，韧性提高、脆性转折点的温度降低。细晶粒钢具有良好的强度和韧性配合，在汽车、船舶、桥梁及工程机械等领域得到广泛应用。
现有技术中低合金高强度钢的强度和韧性不可兼得，在现有技术中只涉及钢板和板带的轧制方法，未涉及棒材圆钢轧制方法，并且轧制过程中需要离线正火步骤，生产成本偏高，不利于节能降本和绿色制造。
发明内容
针对现有技术的不足，本发明的目的在于提供一种高韧性的低合金高强度钢的轧制方法，通过微合金元素和控制轧制及控制冷却工艺技术制定合理的生产工艺控制，成功研发生产一种高韧性的低合金高强度钢的轧制方法，产品的制造过程中，去掉离线正火的步骤，减少工艺制造流程，节约制造成本；采用该工艺和方法所制造的低合金高强度钢，金相组织为细小铁素体加 珠光体，抗拉强度大于630MPa，屈服强度大于500MPa，轧制后晶粒度细小而均匀，晶粒度达9.0级以上，综合力学性能远超常规轧制工艺。
为了实现上述目的，本发明提供如下技术方案：
一种高韧性的低合金高强度钢的轧制方法，所述轧制方法依次包括如下步骤：加热、除鳞、粗轧、连轧、第一次穿水冷却、精轧、第二次穿水冷却和冷床冷却。
以转炉连铸坯为原料，按照质量百分比，所述高韧性的低合金高强度钢的连铸坯各化学成分和含量为：C≤0.20；Si≤0.60；Mn1.00～1.70；Cr≤0.30；P≤0.020；S≤0.020；V0.05～0.10；Al≤0.03；N≤0.025；其余为Fe和不可避免的杂质。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述加热步骤分为四段，依次为预加热、加热一段、加热二段和均热段。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述预热段的温度≤750℃。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述加热一段的温度900～1050℃。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述加热二段的温度1050～1150℃。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述均热段的温度1150～1210℃。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述加热步骤的总加热时间为3～5h。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述均热段的均热时间为30～80min。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述加热步骤在四段步进式加热炉内进行。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述粗轧步骤中，粗轧的入口温度为950～1050℃，粗轧道次为5～7道次，优选地，所述粗轧步骤中设置粗轧机的数量为6架。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所 述连轧步骤包括中轧和预精轧。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述中轧的入口温度为900～1000℃。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述中轧中设置中轧机的数量为6架，中轧道次为5～7道次，优选地，所述中轧道次为6道次。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述预精轧的出口温度为850～950℃。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述预精轧中设置预精轧机的数量为4架，预精轧道次为3～5道次，优选地，所述预精轧道次为4道次。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述第一次穿水冷却，将连轧步骤后的来料进行第一次穿水冷却，其中水冷速度为25～50℃/s，水压为0.2～0.6MPa。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述精轧步骤中，精轧的入口开轧温度为800～850℃。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，采用减定径机组进行精轧。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述减定径机组为三辊减定径机组。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述第二次穿水冷却，将精轧步骤后的钢材进行第二次穿水冷却，其中水冷速度为25～100℃/s，水压为0.2～0.6MPa。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述除鳞步骤中，采用以去氧化铁皮为目地的高压水除鳞，所述高压水的水压为15～20MPa。
进一步优选地，所述高压水的水压为17～20MPa。
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，经过该轧制方法得到高韧性的低合金高强度钢棒材，所述钢棒材的规格为
Figure PCTCN2022092306-appb-000001
上述高韧性的低合金高强度钢的轧制方法，作为一种优选实施方式，所述冷床冷却是指将第二次穿水冷却后得到的钢材在冷床进行空冷。
与现有技术相比，本发明的有益效果是：
(1)在连铸坯的化学成分里，通过添加微合金元素钒V，提高钢的淬透性，减少钢材的变形、避免产生裂纹，进而提高冲击韧性；因为微合金元素钒V仅在900℃以下对再结晶才有推迟作用，所以在奥氏体转变以后，微合金元素钒V几乎已完全溶解，同时微合金元素N进一步加强微合金元素的冲击韧性，充分利用微合金元素钒V、氮N的沉淀强化作用，通过添加微合金元素V的含量提高冲击韧性，同时微合金元素钒V溶入铁素体中有强化作用，形成稳定的碳化物，细化晶粒。
同时采用在线TMCP工艺，控制氮化物的析出过程，形成铁素体和珠光体组织，通过采用较低的终轧温度和冷却速率，再次细化晶粒，细化晶粒的过程中既提高钢的强度，又能改善其塑性和冲击韧性，实现力学性能的高强度控制。
采用该轧制方法可以细化低合金高强度钢的实际晶粒度，得到的低合金高强度钢的综合性能优异，金相组织为细小铁素体加珠光体，抗拉强度大于630MPa，屈服强度大于500MPa，轧制后晶粒度细小而均匀，晶粒度达9.0级以上，-20℃冲击功大于100J，-40℃冲击功大于80J，其综合力学性能远超常规轧制工艺；
(2)在轧制过程中不进行离线正火处理，力学性能也能满足使用要求，这样不仅可以节省加工时间，还能降本增效。
附图说明
图1为对比例2轧制
Figure PCTCN2022092306-appb-000002
规格获得的金相组织；
图2为对比例2轧制
Figure PCTCN2022092306-appb-000003
规格获得的晶粒度(7.5级)；
图3为本发明实施例2轧制
Figure PCTCN2022092306-appb-000004
规格获得的金相组织；
图4为本发明实施例2轧制
Figure PCTCN2022092306-appb-000005
规格获得的晶粒度(9.0级)。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行 清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明所公开的轧制方法是按照连轧工艺参数设计，通过轧制原理的固态相变和塑性变形相结合，采用四段步进式加热炉加热工艺制度和轧制压下制度塑性成材，通过粗轧、中轧、精轧变形制度成材，最后通过控冷工艺控制金属固态相变，得到所需产品优质的组织形态和优越的组织力学性能。
以下结合附图通过实例对本发明的技术方案作进一步详细说明。
一种高韧性的低合金高强度钢的轧制方法，所述轧制方法依次包括如下步骤：加热、除鳞、粗轧、连轧、第一次穿水冷却、精轧、第二次穿水冷却和冷床空冷；以转炉连铸坯为原料，按照质量百分比，连铸坯中各化学成分和含量为：C≤0.20；Si≤0.60；Mn1.00～1.70；Cr≤0.30；P≤0.020；S≤0.020；V0.05～0.10；Al≤0.03；N≤0.025；余量为Fe和不可避免的杂质。
连铸坯的化学成分中，通过添加微合金元素钒V，提高钢的淬透性，减少钢的变形和产生裂纹，进而提高冲击韧性；因为微合金元素钒V仅在900℃以下对再结晶才有推迟作用，所以在奥氏体转变以后，微合金元素钒V几乎已完全溶解，同时微合金元素N进一步加强微合金元素钒V的冲击韧性，充分利用微合金元素钒V、氮N的沉淀强化作用。
晶粒细化能改善塑性和韧性的原因在于细的晶粒为塑性变形的发生和扩展提供了更好的条件。凡是使奥氏体向铁素体转变温度Ar3降低的因素都有晶粒细化的趋势。通过添加微合金元素V的含量提高冲击韧性，同时微合金元素钒V溶入铁素体中有强化作用，形成稳定的碳化物，细化晶粒。
轧制方法依次包括如下步骤：
(1)加热
加热步骤在四段步进式加热炉内进行；加热步骤分为四段，依次为预加热、加热一段、加热二段和均热段。
预热段的温度≤750℃(比如600℃、650℃、665℃、700℃、750℃及之中任意二个温度之间的区间段或者区间点)；即如果炉温温度超过750℃，则可能会因钢坯导热速率过快，钢坯和加热炉的温差过大，进而导致铸坯或者最终轧材表面产生裂纹。
加热一段的温度900～1050℃(比如900℃、950℃、980℃、1000℃、1010℃、1050℃及之中任意二个温度之间的区间段或者区间点)。加热二段的温度1050～1150℃(比如1050℃、1080℃、1100℃、1110℃、1130℃、1150℃及之中任意二个温度之间的区间段或者区间点)。加热一段和加热二段的主要作用在于：减少能源消耗，减少钢坯的氧化烧损。
均热段的温度1150～1210℃(比如1150℃、1160℃、1165℃、1170℃、1185℃、1190℃、1205℃、1210℃及之中任意二个温度之间的区间段或者区间点)。均热段的主要作用在于：减少能源消耗，减少钢坯氧化烧损，同时减少钢坯脱碳。
加热步骤的总加热时间为3～5h(比如3.5h、4h、4.5h、4.8h及之中的任意两个时间段之间的时间点)；所述均热段的均热时间为30～80min(比如30min、35min、40min、45min、50min、55min、60min、70min、75min、80min及之中的任意两个时间段之间的时间点)。
加热步骤实现如下四个目标：第一，省略离线正火的步骤可以减少能源消耗，节约成本；第二，四段加热工序减少钢坯的氧化烧损；第三，减少钢坯脱碳；第四，减少因加热时间过长带来最终轧材表面裂纹。
(2)除鳞
将加热后的钢坯采用高压水除鳞以去氧化铁皮，高压水的压力15～20MPa(比如15MPa、16.5MPa、17MPa、18MPa、20MPa及之中的任意两个压力值之间的压力值)；高压水的压力值优选为17～20MPa。利用高压水去除钢材表面氧化铁皮，压力低于15MPa对表面氧化铁皮的清理不干净、不彻底，影响钢材轧制效果。
(3)粗轧
粗轧步骤优选设置6架粗轧机；其中粗轧的入口温度为950～1050℃(比如950℃、980℃、1000℃、1020℃、1035℃、1050℃及之中任意二个温度之间的区间段或者区间点)，粗轧道次为5～7道次；粗轧道次优选为6道次。粗轧步骤采用连轧的轧制方法，主要通过塑性变形改变钢坯坯料表面大小，孔型设计采用箱型孔设计，以大压下工艺改变及减少坯料断面形状。
(4)连轧
连轧步骤包括中轧和预精轧，中轧的入口温度为900～1000℃(比如 905℃、920℃、940℃、950℃、970℃、1000℃及之中任意二个温度之间的区间段或者区间点)，中轧步骤中优选设置6架中轧机，中轧道次为5～7道次；中轧道次优选为6道次。孔型设计主要采用椭圆和圆孔型设计，通过轧制工艺，使坯料断面形状接近成品形状。
预精轧的出口温度为850～950℃(比如855℃、870℃、890℃、900℃、910℃、920℃、930℃、940℃、950℃及之中任意二个温度之间的区间段或者区间点)；预精轧步骤中优选设置4架预精轧机，预精轧道次为3～5道次，预精轧道次优选为4道次。孔型设计主要采用椭圆和圆孔型设计，通过轧制工艺，使坯料断面形状接近成品形状。
(5)第一次穿水冷却
将连轧步骤后的来料进行第一次穿水冷却，第一次穿水冷却后温度为750～800℃(比如750℃、765℃、780℃、795℃、798℃、800℃及之中任意二个温度之间的区间段或者区间点)，其中第一次穿水冷却水冷速度为25～50℃/s，水压为0.2～0.6MPa。通过控制第一次穿水冷却的温度及水冷速度，控制精轧前的钢材温度，得到精轧所需目标温度。
(6)精轧
将步骤(5)得到的轧材进入减定径精轧机组进行轧制，减定径精轧机组优选为三辊减定径机组，即KOCKS减定径精轧机组，入口开轧温度为800～850℃(比如800℃、810℃、820℃、824℃、832℃、850℃及之中任意二个温度之间的区间段或者区间点)。采用三辊减定径机组精轧能更好地实施低温轧制，从而提高非调质钢晶粒度、综合力学性能、为非调质钢的生产提供其优异性能。
(7)第二次穿水冷却
将精轧后的钢材进行第二次穿水冷却，将精轧步骤后的钢材进行第二次穿水冷却的温度为600～700℃(比如600℃、625℃、640℃、662℃、683℃、700℃及之中任意二个温度之间的区间段或者区间点)，其中水冷速度为25～100℃/s，水压为0.2～0.6MPa。通过精轧后进行第二次穿水冷却并控制第二次穿水冷却的温度及水冷速度，控制钢材温度，得到钢材最终所需金相组织和力学性能。
(8)冷床冷却即冷床空冷
将第二次穿水冷却后得到的钢材在冷床进行空冷，最终得到成品钢材。
步骤(1)至步骤(8)所述的控制轧制和控制冷却技术是细化高碳钢钢种晶粒度的主要步骤，通过控制加热温度、变形程度和冷却速度相结合，达到细化实际晶粒度，提高钢材刚性和韧性的目的。
同时采用在线TMCP工艺(即热机械控制工艺)，控制氮化物的析出过程，形成均匀的铁素体和珠光体组织，通过采用较低的终轧温度和冷却速率，再次细化晶粒，细化晶粒的过程中既提高钢的强度，又能改善其塑性和冲击韧性，实现力学性能的高强度控制。
本发明所述一种高韧性的低合金高强度钢的轧制方法，其方法独特，采用微量合金元素和热机械控制工艺的控制轧制控制冷却技术共同作用实现在线控制，采用该工艺方法可以细化高韧性的低合金高强度钢的实际晶粒度，所述高韧性的低合金高强度钢综合性能优异，金相组织为细小铁素体加珠光体，抗拉强度大于630MPa，屈服强度大于500MPa，轧制后晶粒度细小而均匀，晶粒度达9.0级以上，-20℃夏氏V型冲击功大于100J，-40℃夏氏V型冲击功大于80J，其综合力学性能远超常规轧制方法。
高韧性的低合金高强度钢在制造过程中不进行离线正火处理，力学性能也能满足使用要求，这样不仅可以节省加工时间，还能降本增效。
实施例1
实施例1提供一种高韧性的低合金高强度钢的轧制方法，所需成品规格为
Figure PCTCN2022092306-appb-000006
选择300×400mm断面连铸坯；其中连铸坯中各化学成分的按质量百分比，如表2所示，质量分数共计为100％；包括以下步骤：
(1)加热：将断面连铸坯切断后采用冷送方式放入四段步进式加热炉中进行加热，预热段的温度685℃，加热一段的温度1005℃，加热二段的温度1086℃，均热段的温度1175℃；该加热步骤中的总加热时间为3.8h，均热段的均热时间为43min。
(2)除鳞：将加热后的钢坯采用高压水除鳞以去氧化铁皮，高压水的压力18.0MPa。
(3)粗轧：将除鳞后的钢坯送入高刚度粗轧机(6架)进行粗轧得到粗轧钢坯；粗轧入口温度为1015℃，粗轧道次为6道次。
(4)连轧：将步骤(3)得到的粗轧钢坯送入连轧机组，中轧入口温度 为925℃，中轧道次为6道次，预精轧钢坯的出口温度为910℃，预精轧钢坯道次为4道次。
(5)第一次穿水冷却：将预精轧后的轧材进行第一次穿水冷却；温度冷却至790℃；水冷速度为40℃/s，水压为0.5MPa。
(6)精轧：将预精轧后得到规格
Figure PCTCN2022092306-appb-000007
的轧材通过KOCKS减定径机组进行轧制，所述减定径机组轧制时轧材的入口温度为845℃，得到规格为
Figure PCTCN2022092306-appb-000008
钢棒材。
(7)第二次穿水冷却：将精轧后的轧材进行第二次穿水冷却；温度冷却至685℃；水冷速度为75℃/s，水压为0.6MPa。
(8)冷床冷却(冷床空冷)：将步骤(7)得到的规格为
Figure PCTCN2022092306-appb-000009
钢棒材在冷床空冷，最终得到成品钢棒材。
实施例1得到的高韧性的低合金高强度钢热轧态的组织为均匀的铁素体和珠光体，实际晶粒度为9.0级，其钢材产品力学性能如表3所示。实施例1得到的高韧性的低合金高强度钢热轧态的组织为均匀的铁素体和珠光体，实际晶粒度为9.0级，由表3可知，其钢材产品力学性能优越。
实施例2
实施例2提供一种高韧性的低合金高强度钢的轧制方法，所需成品规格为
Figure PCTCN2022092306-appb-000010
选择300×400mm断面连铸坯；其中连铸坯中各化学成分的按质量百分比，如表2所示，质量分数共计为100％；所述轧制方法依次经过以下步骤：(1)加热，(2)除鳞，(3)粗轧，(4)连轧，(5)第一次穿水冷却，(6)精轧，(7)第二次穿水冷却和(8)冷床冷却(冷床空冷)，实施例2的加工步骤同实施例1，其具体步骤的加工参数参见表1，其钢材产品力学性能如表3所示。
实施例2得到的高韧性的低合金高强度钢热轧态的组织为均匀的铁素体和珠光体，如图3所示；实际晶粒度为9.0级，如图4所示。由表3可知，其钢材产品力学性能优越。
实施例3
实施例3提供一种高韧性的低合金高强度钢的轧制方法，所需成品规格为
Figure PCTCN2022092306-appb-000011
选择300×400mm断面连铸坯；其中连铸坯中各化学成分的按质量百分比，如表2所示，质量分数共计为100％；所述轧制方法依次经过 以下步骤：(1)加热，(2)除鳞，(3)粗轧，(4)连轧，(5)第一次穿水冷却，(6)精轧，(7)第二次穿水冷却和(8)冷床冷却(冷床空冷)，实施例3的加工步骤同实施例1，其具体步骤的加工参数参见表1，其钢材产品力学性能如表3所示。
实施例3得到的高韧性的低合金高强度钢热轧态的组织为均匀的铁素体和珠光体，实际晶粒度为9.0级，由表3可知，其钢材产品力学性能优越。
实施例1-3的具体加工步骤参数如表1所示。
表1 实施例1-3所得钢材的具体加工步骤参数
Figure PCTCN2022092306-appb-000012
实施例1-3所选用的连铸坯化学成分由表2所示。
表2 实施例1-3所选用的连铸坯化学成分
Figure PCTCN2022092306-appb-000013
实施例1-3得到的高韧性的低合金高强度钢的各项性能由表3所示。
表3 实施例1-3所得钢材力学性能参数
性能参数 标准值 实施例1 实施例2 实施例3
屈服强度(MPa) ≥420 523 525 525
抗拉强度(MPa) ≥520 648 654 654
延伸(％) ≥19 32 28 28
-20℃夏氏V型冲击功(J) ≥47 135 132 132
-40℃夏氏V型冲击功(J) ≥31 103 105 105
实施例4-7
实施例4-7提供一种高韧性的低合金高强度钢的轧制方法，所述轧制方法依次经过以下步骤：(1)加热，(2)除鳞，(3)粗轧，(4)连轧，(5)第 一次穿水冷却，(6)精轧，(7)第二次穿水冷却和(8)冷床冷却(冷床空冷)，实施例4-7的加工步骤及机械参数同实施例1；实施例4-7所用连铸坯中各化学成分的含量按质量百分比，如表4所示，质量分数共计为100％。
表4 实施例4-7所选用的连铸坯化学成分
Figure PCTCN2022092306-appb-000014
实施例4-7得到的高韧性的低合金高强度钢的各项性能如表5所示。
表5 实施例4-7所得钢材力学性能参数
性能参数 标准值 实施例4 实施例5 实施例6 实施例7
屈服强度(MPa) ≥420 530 537 528 525
抗拉强度(MPa) ≥520 658 649 660 652
延伸(％) ≥19 30 29 31 30
-20℃夏氏V型冲击功(J) ≥47 129 135 130 132
-40℃夏氏V型冲击功(J) ≥31 104 108 110 106
由表5可知，实施例4-7得到的高韧性的低合金高强度钢热轧态的组织为均匀的铁素体和珠光体，实际晶粒度为9.0级，其钢材产品力学性能优越。
对比例1
所需成品规格为
Figure PCTCN2022092306-appb-000015
选择300×400mm断面连铸坯；连铸坯中各化学成分和含量为：C0.45；Si 0.28；Mn1.46；Cr 0.16；V0.06；N0.010；Al 0.020；P≤0.020；S≤0.020；其余为Fe和不可避免的杂质。合金钢材加工步骤及参数如表7所示。
如表6所示，由于连铸坯的化学成分中碳C含量为0.45％，即C>0.20，如表8所示，所轧制钢材的延伸率为18％，-20℃夏氏V型冲击功为32J；-40℃夏氏V型冲击功为17J。
对比例2
所需成品规格为
Figure PCTCN2022092306-appb-000016
选择300×400mm断面连铸坯；连铸坯中各化学成分和含量为：C0.16；Si 0.30；Mn 0.8；Cr 0.15；V0.07；N0.012；Al 0.020；P≤0.020；S≤0.020，余量为Fe和不可避免的杂质。合金钢材加工步骤及参数如表7所示。
如表6所示，由于连铸坯的化学成分中锰Mn含量为0.8，即Mn<1.0，如表8所示，所轧制钢材的延伸率为26％，-20℃夏氏V型冲击功为54J；-40℃夏氏V型冲击功为25J。
对比例3
所需成品规格为
Figure PCTCN2022092306-appb-000017
选择300×400mm断面连铸坯；连铸坯中各化学成分和含量为：C0.16；Si 0.30；Mn1.40；Cr 0.15；N0.011；Al 0.022；P≤0.020；S≤0.020；余量为Fe和不可避免的杂质。合金钢材加工步骤及参数如表7所示。
如表6所示，由于连铸坯的化学成分中未添加钒V，如表8所示，所轧制钢材的延伸率为25％，-20℃夏氏V型冲击功为35J；-40℃夏氏V型冲击功为19J。
对比例4
所需成品规格为
Figure PCTCN2022092306-appb-000018
选择300×400mm断面连铸坯；连铸坯中各化学成分和含量为：C0.16；Si 0.32；Mn1.47；Cr 0.15；V0.06；N0.040；Al 0.020；P≤0.020；S≤0.020；余量为Fe和不可避免的杂质。合金钢材加工步骤及参数如表7所示。
如表6所示，由于连铸坯的化学成分中氮N的含量为0.040，即N>0.025，如表8所示，所轧制钢材的延伸率为27％，-20℃夏氏V型冲击功为62J；-40℃ 夏氏V型冲击功为37J。
由表8可知，对比例1-4的轧制方法相对于本申请公开的轧制方法所得钢材的力学性能中-20℃夏氏V型冲击功都小于100J；-40℃夏氏V型冲击功都小于80J，轧制后合金钢材晶粒度达不到9.0级以上。
表6 对比例1-4所选用的连铸坯化学成分
Figure PCTCN2022092306-appb-000019
对比例1-4的合金钢材加工步骤及参数如表7所示。
表7 对比例1-4所得钢材的具体加工步骤参数
加工参数 对比例1 对比例2 对比例3 对比例4
钢坯尺寸(mm×mm) 300×400 300×400 300×400 300×400
预热温度(℃) 702 687 685 700
加热一段温度(℃) 980 1001 995 1005
加热二段温度(℃) 1068 1075 1098 1094
均热段温度(℃) 1170 1180 1182 1191
均热段时间(min) 53 47 56 62
总加热时间(h) 4.2 3.9 4.6 4.8
除鳞水压(MPa) 18.5 18.1 18.2 18.3
粗轧入口温度(℃) 1002 1003 1011 1006
中轧入口温度(℃) 952 956 960 945
预精轧温度(℃) 922 930 933 935
第一次穿水冷却温度(℃) 785 / 780 782
水冷速度(℃/s)/水压(MPa) 38/0.5 / 33/0.5 32/0.5
精轧入口温度(℃) 835 880 820 821
第二次穿水冷却温度(℃) 680 / 670 675
水冷速度(℃/s)/水压(MPa) 72/0.6 / 65/0.5 62/0.5
对比例1-4得到的合金钢材的各项性能由表8所示。
表8 对比例1-4所得钢材力学性能参数
Figure PCTCN2022092306-appb-000020
尽管已描述了本发明的优选实施例，但本领域内的技术工程人员可对这些实施例作出另外的变更和修改。所以，所附权利要求应解释为包括优选实施例以及落入本发明范围的所有变更和修改。
以上所述仅为本发明的优选实施例，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (16)

  1. 一种高韧性的低合金高强度钢的轧制方法，其特征在于，所述轧制方法依次包括如下步骤：
    加热、除鳞、粗轧、连轧、第一次穿水冷却、精轧、第二次穿水冷却和冷床冷却；
    以转炉连铸坯为原料，按照质量百分比，所述连铸坯中各化学成分和含量为：C≤0.20；Si≤0.60；Mn 1.37～1.70；Cr≤0.30；P≤0.020；S≤0.020；V 0.07～0.10；Al≤0.03；N 0.008～0.025；其余为Fe和不可避免的杂质；
    所述第一次穿水冷却后温度为765～800℃；
    所述精轧步骤中，精轧的入口开轧温度为832～850℃；
    所述第二次穿水冷却，将所述精轧步骤后的钢材进行所述第二次穿水冷却的温度为600℃～700℃，其中水冷速度为25～100℃/s，水压为0.2～0.6MPa；
    所述冷床冷却是指将第二次穿水冷却后得到的钢材在冷床进行空冷。
  2. 根据权利要求1所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述加热步骤分为四段，依次为预加热段、加热一段、加热二段和均热段，
    所述预加热段的温度≤750℃；
    所述加热一段的温度900～1050℃；
    所述加热二段的温度1050～1150℃；
    所述均热段的温度1150～1210℃。
  3. 根据权利要求2所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述加热步骤的总加热时间为3～5h；所述均热段的均热时间为30～80min。
  4. 根据权利要求2所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述加热步骤在四段步进式加热炉内进行。
  5. 根据权利要求1或2所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述粗轧步骤中，粗轧的入口温度为950～1050℃，粗轧道次为5～7道次。
  6. 根据权利要求5所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述粗轧步骤中设置粗轧机的数量为6架；所述粗轧道次为6道次。
  7. 根据权利要求6所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述连轧步骤包括中轧和预精轧，
    所述中轧的入口温度为900～1000℃，中轧道次为5～7道次；
    所述预精轧的出口温度为850～950℃，预精轧道次为3～5道次。
  8. 根据权利要求7所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述中轧中设置中轧机的数量为6架；所述中轧道次为6道次。
  9. 根据权利要求7所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述预精轧中设置预精轧机的数量为4架；所述预精轧道次为4道次。
  10. 根据权利要求5所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述第一次穿水冷却，将连轧步骤后的来料进行第一次穿水冷却，其中水冷速度为25～50℃/s，水压为0.2～0.6MPa。
  11. 根据权利要求5所述的高韧性的低合金高强度钢的轧制方法，其特征在于：采用减定径机组进行精轧。
  12. 根据权利要求11所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述减定径机组为三辊减定径机组。
  13. 根据权利要求5所述的高韧性的低合金高强度钢的轧制方法，其特 征在于：所述除鳞步骤中，采用以去氧化铁皮为目地的高压水除鳞，所述高压水的水压为15～20MPa。
  14. 根据权利要求13所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述高压水的水压为17～20MPa。
  15. 根据权利要求1-2任一项所述的高韧性的低合金高强度钢的轧制方法，其特征在于：经过该轧制方法得到高韧性的低合金高强度钢棒材。
  16. 根据权利要求15所述的高韧性的低合金高强度钢的轧制方法，其特征在于：所述钢棒材的规格为
    Figure PCTCN2022092306-appb-100001
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