WO2023040581A1 - Barre d'acier structurale faiblement alliée de qualité q500, et procédé de laminage régulé et de laminage à froid régulé afférant - Google Patents

Barre d'acier structurale faiblement alliée de qualité q500, et procédé de laminage régulé et de laminage à froid régulé afférant Download PDF

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WO2023040581A1
WO2023040581A1 PCT/CN2022/113683 CN2022113683W WO2023040581A1 WO 2023040581 A1 WO2023040581 A1 WO 2023040581A1 CN 2022113683 W CN2022113683 W CN 2022113683W WO 2023040581 A1 WO2023040581 A1 WO 2023040581A1
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rolling
controlled
cooling
alloy structural
structural steel
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Chinese (zh)
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郭士北
汪洋
彭峰
王占忠
张越
马建祎
杜正龙
陈君
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大冶特殊钢有限公司
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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
    • B21B1/16—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 wire rods, bars, merchant bars, rounds wire or material of like small cross-section
    • 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
    • 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
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/24—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
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • 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
    • 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
    • C22C38/18—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
    • 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
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Definitions

  • the invention relates to a Q500 steel grade low-alloy structural steel bar and a rolling method thereof, belonging to the field of controlled rolling and controlled cooling of steel rolling.
  • Q500 steel is a kind of bridge steel.
  • bridge steel With the application of high-strength bridge steel, brittle fracture accidents of steel structures have occurred frequently, and the economic losses and casualties caused by them have become more and more serious.
  • high-strength bridge steel cannot meet the design requirements of modern bridges in terms of toughness and other mechanical properties, which largely restricts its large-scale promotion and use in bridges.
  • Controlled rolling and controlled cooling method is a method to significantly improve the mechanical properties of steel by controlling rolling temperature and controlled cooling.
  • the use of controlled rolling and controlled cooling can greatly reduce the production cost of steel, and make low-carbon equivalent low-alloy high-strength structural steel obtain high Strength and low temperature impact toughness, greatly reduced production.
  • the present invention provides a controlled rolling and controlled cold rolling method to effectively improve the strength and impact toughness of steel, so that low carbon equivalent low alloy structural steel can obtain high strength At the same time as low temperature impact toughness, the production cost is greatly reduced.
  • the present invention adopts the following technical solutions:
  • the C content is 0.10% to 0.18% (for example, 0.11%, 0.12%, 0.14%, 0.15%, 0.16%, 0.17% ).
  • the present invention does not add Ni, Mo, Nb, Ti elements, offsets the addition of precious alloys by increasing the C content, designs the C content to be 0.05% to 0.18%, preferably 0.10% to 0.18%, and adopts low carbon equivalent low alloy structural steel High strength and low temperature impact toughness are obtained, and at the same time, based on the chemical composition of Q500 steel grade in the GB/T1591-2018 standard, since the invention does not add precious alloys such as Ni, Mo, Nb, Ti, etc., the production cost is reduced.
  • the specification (diameter) of the Q500 steel-grade low-alloy structural steel bar is 20-120 mm.
  • the GB/T1591-2018 standard requires that the CEV of Q500 steel grade bars shall be ⁇ 0.47% when the specification is ⁇ 63mm, and the CEV ⁇ 0.48% when the specification is >63mm.
  • the invention designs CEV ⁇ 0.45%. Under the condition of low CEV, the Q500 steel grade can obtain high strength and low-temperature impact energy through controlled rolling and controlled cooling.
  • the level of CEV affects the welding performance of materials.
  • it is weldability the lower the CEV, the better the weldability, but on the other hand, CEV also affects the strength of the material. Under the same conditions, the lower the CEV, the lower the strength.
  • the low-CEV steel can obtain high strength and at the same time have good low-temperature impact toughness.
  • the CEV is 0.40-0.45% (for example, 0.41%, 0.42%, 0.43%, 0.44%).
  • the performance of the Q500 steel-grade low-alloy structural steel bar is as follows: R p0.2 ⁇ 470MPa, R m is 600-750MPa, A ⁇ 25%, - Longitudinal KV 2 ⁇ 100J at 40°C.
  • the present invention also provides a controlled rolling and controlled cold rolling method for the above-mentioned low-alloy structural steel bar, which adopts the following technical scheme:
  • a controlled rolling and controlled cold rolling method for the above-mentioned Q500 steel grade low-alloy structural steel bar includes the following steps in sequence: heating, rolling, cooling, KOCKS rolling and secondary cooling; In the rolling step, the heated billet is rolled, and the rolling start temperature is 1000-1050°C (for example, 1010°C, 1020°C, 1030°C, 1040°C, 1045°C).
  • the controlled rolling and controlled cold rolling method uses ⁇ 100mm ⁇ 390mm steel billet round billet as raw material, or (100mm ⁇ 300mm) ⁇ (100mm ⁇ 400mm)
  • the steel billet is used as the raw material, and the specification (diameter) of the finished bar obtained by final rolling is 20mm-120mm (for example, 40mm, 60mm, 80mm, 100mm, 110mm).
  • the soaking temperature of the billet is 1100-1199°C (for example, 1120°C, 1140°C, 1150°C, 1160°C, 1180°C , 1195°C).
  • the general soaking temperature is 1200-1260°C.
  • the present invention adopts a lower soaking temperature, mainly considering two aspects: 1.
  • the low-temperature soaking meets the requirements of the high-temperature section of the billet, and has no influence on the subsequent rolling temperature; 2.
  • Low temperature soaking is easier to obtain the desired final rolling temperature in the process of controlled rolling and controlled cooling.
  • the finishing rolling temperature of the two-roll rolling is 850-900°C (for example, 860°C, 870°C, 880°C, 890°C).
  • the rolling method is two-roll rolling.
  • the rolled piece obtained by the two-roll rolling is used as a masterbatch for KOCKS rolling.
  • the two-roll rolling adopts a short stress line rolling mill, which can effectively improve the rolling stability and ensure the deformation of the rolled piece
  • two-roll rolling can achieve a large compression ratio (10-30), improve the uniformity of the core structure of the rolled material, and help improve the uniformity of the rolled material's performance.
  • the cooling adopts spray cooling, and the rolled piece obtained after the final rolling is cooled to 800-849°C (for example, 810°C , 820°C, 830°C, 840°C, 845°C) followed by KOCKS rolling.
  • the present invention adopts spray cooling to cool the rolled piece obtained after finishing rolling to 800-849° C. before performing KOCKS rolling.
  • the present invention adopts spray cooling, uses a cooling device to rapidly cool the steel surface, and reduces the temperature of the core of the rolled piece through heat conduction, so that the temperature difference between the core temperature and the surface temperature of the rolled piece is gradually reduced.
  • the purpose of cooling the rolled piece to 800-849° C. is to promote grain refinement through deformation at the final rolling temperature near the temperature in the two-phase region, so as to achieve uniform structure of the rolled piece.
  • the water tank cooling channel that should be selected in the spray cooling step is determined.
  • the parameters of the cooling channel of the water tank that is, the diameter of the channel of the water tank
  • the spray cooling speed can be calculated according to the number of water tanks put into use and the pressure of cooling water.
  • the spray cooling method in which the cooling intensity is gradually reduced can prevent production failure caused by bending of the head of the rolled piece.
  • the cooled rolled piece is subjected to KOCKS rolling; the amount of deformation is 20% to 100% (for example, 25%, 30%, 50%, 70%, 80%, 90%); preferably, the KOCKS rolling uses three KOCKS rolling mills, more preferably, the distribution of the three rolling mills is positive Y and inverted Y alternately, using three rolls The rolling range of 120° mutually realizes the reduction and sizing of bars.
  • a larger amount of deformation is more beneficial to the improvement of the grain size and mechanical properties of the finally obtained material.
  • KOCKS rolling adopts three-roll rolling technology, which has the following advantages compared with traditional two-roll rolling technology:
  • the deformation efficiency of three-roll rolling is much higher than that of two-roll rolling.
  • the rolling force acts on the rolled piece from three sides, the deformation in the three-roll pass is more converted into extension, and the temperature rise of rolling (that is, the temperature rise of the rolled piece surface during the rolling process rise) and lower, which is beneficial to the temperature-controlled rolling of the rolled piece; the uniform deformation along the interface of the rolled piece in the three-roll pass can obtain a uniform metallographic structure with consistent grain size.
  • the secondary cooling step cools the KOCKS rolled piece, and the secondary cooling includes secondary spray cooling and cooling bed cooling.
  • the second spray cooling is performed on the rolled piece after KOCKS rolling, and the cooling rate is 20°C/min ⁇ 35°C. °C/min (eg, 23°C/min, 25°C/min, 30°C/min, 33°C/min); ensure sufficient cooling intensity for achieving upper cooling bed temperature.
  • the cooling bed cooling performs cooling bed cooling on the bar obtained after the second spray cooling
  • the temperature of the upper cooling bed is ⁇ 570°C, preferably 530°C ⁇ 570°C (for example, 540°C, 550°C, 560°C)
  • the temperature of the lower cooling bed is 200-250°C (for example, 210°C, 220°C, 230°C, 240°C).
  • the near-surface layer of the bar structure is a sorbite (S) structure, and the inside is a ferrite+pearlite structure (F+P).
  • the rod prepared in the conventional process has a structure of ferrite + pearlite.
  • Sorbitite is a quenched and tempered structure.
  • the second spray cooling rate is relatively large, especially after cooling near the surface, the temperature reaches below the martensitic transformation temperature (Ms) to form martensite, but the internal temperature Relatively high, after spraying, the internal temperature conducts outward, and finally returns to 530-570°C on the cooling bed. After returning to temperature, it is equivalent to a self-tempering process, and martensite transforms into sorbite.
  • Ms martensitic transformation temperature
  • the present invention adopts a lower soaking temperature to meet the requirements of the high-temperature section in the billet heating step, ensure uniform heating of the billet, and have no effect on the subsequent rolling temperature; and the low-temperature soaking is easier to obtain in the controlled rolling and cooling process.
  • the desired finishing temperature is a lower soaking temperature to meet the requirements of the high-temperature section in the billet heating step, ensure uniform heating of the billet, and have no effect on the subsequent rolling temperature; and the low-temperature soaking is easier to obtain in the controlled rolling and cooling process.
  • the desired finishing temperature is used to meet the requirements of the high-temperature section in the billet heating step, ensure uniform heating of the billet, and have no effect on the subsequent rolling temperature; and the low-temperature soaking is easier to obtain in the controlled rolling and cooling process.
  • the uniformity of the structure of the rolled piece can be realized, and the uniformity of the performance of the rolled piece can be improved.
  • the yield of steel products with the same chemical composition can be significantly improved at relatively low starting and finishing temperatures, relatively high spray intensity and relatively low upper cooling bed temperature. strength and low temperature impact properties.
  • Fig. 1 is the 100-fold and 500-fold metallographic structure diagrams of the steel produced in Example 1 of the present invention at the same site at 5 mm subcutaneously, wherein Fig. 1A is a 100-fold metallographic structure diagram, and Fig. 1B is a 500-fold metallographic structure diagram picture.
  • Fig. 2 is the 100-fold metallographic structure diagram and the 500-fold metallographic structure diagram of the steel produced in Example 1 of the present invention at the same position at 15 mm subcutaneously, wherein (c) is the 100-fold metallographic structure diagram, (d) It is a metallographic structure map at 500 times.
  • Fig. 3 is the 100-fold metallographic structure diagram and the 500-fold metallographic structure diagram of the steel produced in Example 1 of the present invention at the same position at 25 mm subcutaneously, wherein (e) is a 100-fold metallographic structure diagram, (f) It is a metallographic structure map at 500 times.
  • Fig. 4 is the 100-fold and 500-fold metallographic structure diagrams of the steel produced in Comparative Example 1 at the same site at 5 mm subcutaneously, wherein (g) is a 100-fold metallographic structure diagram, and (h) is a 500-fold metallographic structure diagram .
  • Fig. 5 is the 100-fold metallographic structure diagram and the 500-fold metallographic structure diagram of the steel produced in Comparative Example 1 at the same position at 15 mm subcutaneously, wherein (i) is a 100-fold metallographic structure diagram, and (j) is a 500-fold metallographic structure diagram Metallographic histogram.
  • Fig. 6 is the 100-fold metallographic structure diagram and the 500-fold metallographic structure diagram of the steel produced in Comparative Example 1 at the subcutaneous 25mm place in the same position, wherein (k) is a 100-fold metallographic structure diagram, and (l) is a 500-fold metallographic structure diagram Metallographic histogram.
  • This embodiment provides a controlled rolling and controlled cold rolling method for Q500 steel grade low-alloy structural steel bars, using a 390 mm steel billet round billet as a raw material to roll a finished product with a specification of 100 mm; the chemical composition of the steel billet (by mass percent, wt%) includes: C: 0.16; Si: 0.30; Mn: 1.40; P: 0.020; S: 0.008; Cr: 0.06; V: 0.06; Iron and unavoidable impurities, and CEV: 0.42.
  • the controlled rolling and controlled cold rolling method sequentially comprises the following steps: heating, rolling, spray cooling, KOCKS rolling, and cooling. Specific steps are as follows:
  • (1) Heating Using a segmented heating process, the steel billet is placed in a heating furnace for heating.
  • the preheating temperature is 680°C
  • the heating temperature of the first stage is 1030°C
  • the heating temperature of the second stage is 1130°C
  • the soaking temperature is 1130°C.
  • Spray cooling the rolled piece obtained after final rolling is sprayed and cooled, and the rolled piece passes through 1#, 2# and 3# water tanks successively, and the process parameters of specifically sprayed cooling are as shown in Table 1; KOCKS rolling is carried out after 830°C. Table 1 lists the process parameters of spray cooling in this embodiment.
  • the cooling channel of the water tank containing the nozzle is selected according to the size of the rolling incoming material (ie, the rolled piece obtained from the final rolling).
  • the cooling intensity of spray cooling is gradually reduced to prevent production failure caused by bending of the head of the rolled piece.
  • KOCKS rolling adopts three-roll rolling technology, which has the following advantages compared with traditional two-roll rolling technology:
  • the deformation efficiency of three-roll rolling is much higher than that of two-roll rolling.
  • the rolling force acts on the rolled piece from three sides to the center, and the deformation in the three-roll pass is more transformed into extension, and the rolling temperature rise is reduced, which is beneficial to the temperature-controlled rolling of the rolled piece;
  • the uniform deformation along the interface of the rolled piece can obtain a uniform metallographic structure and a consistent grain size.
  • Cooling step including the second spray cooling and cooling bed cooling.
  • the second spray cooling the rolled piece after KOCKS rolling is sprayed and cooled for the second time;
  • the second cooling needs to achieve a strong cooling effect, so the opening of the water tank must be the largest; but the 6# cooling water tank is adjacent to the shearing equipment, and excessive cooling intensity will cause uneven shear stress distribution during the shearing process
  • the rolled piece is evenly bent, so a lower cooling rate should be used when the rolled piece passes through the 6# water tank.
  • Cooling bed cooling Cooling the rods obtained after spray cooling, the temperature of the upper cooling bed is 570°C; the temperature of the lower cooling bed is 230-250°C.
  • the final bar size is ⁇ 100mm, and its properties are shown in Table 4.
  • Figure 1 is the metallographic structure of the bar prepared in this example at different magnifications at the same part of the subcutaneous 5mm, wherein Figure 1A is the metallographic structure magnified 100 times, and Figure 1B is the metallographic structure magnified 500 times. From Figure 1 ( Figure 1A and Figure 1B), it can be seen that the structure of the bar is uniform, and its structure is sorbite (S) with a grain size of 9 grades.
  • S sorbite
  • Fig. 2 is the metallographic structure of the bar prepared in this embodiment at different magnifications at the subcutaneous 15mm of the same part, wherein (c) is the metallographic structure magnified 100 times, and (d) is the metallographic structure magnified 500 times . It can be seen from Figure 2 that the structure of the bar is uniform, and its structure is ferrite + pearlite (F+P), with a grain size of 9 grades.
  • F+P ferrite + pearlite
  • Fig. 3 is the metallographic structure of the bar prepared in this embodiment at different magnifications at the subcutaneous 25mm of the same part, wherein (e) is the metallographic structure magnified 100 times, and (f) is the metallographic structure magnified 500 times . It can be seen from Figure 3 that the structure of the bar is uniform, its structure is F+P, and the grain size is 8 grades.
  • This embodiment provides a controlled rolling and controlled cold rolling method for Q500 steel grade low-alloy structural steel bars.
  • the steel billet round billet with a specification of 390mm is used as a raw material.
  • the chemical composition of the steel billet (by mass percentage, wt%) includes : C: 0.11; Si: 0.35; Mn: 1.45; P: 0.018; S: 0.005; Cr: 0.18; V: 0.08; Al: 0.030; N: 0.0100; 0.404.
  • Example 2 Using the same controlled rolling and controlled cold rolling method as in Example 1, the following steps are successively included: heating, rolling, spray cooling, KOCKS rolling, and cooling.
  • the final bar specification is ⁇ 100mm, and its properties are shown in Table 4. shown. It can be seen from Table 4 that the impact of the steel bar obtained by the present invention through controlled rolling and controlled cooling has reached more than 100J at -40°C, meeting the GB/T1591-2018 standard on Q500 steel grades (three grades of Q500MC, Q500MD and Q500ME) performance requirements.
  • the bar prepared in this embodiment has a structure of sorbite (S) at the subcutaneous 5mm place in the same position, with a grain size of 9 grades, and the bar structure is uniform;
  • the grain size is grade 9, and the structure of the rod is uniform;
  • the structure at 25mm subcutaneous in the same part is F+P, the grain size is grade 8, and the structure of the rod is uniform.
  • This embodiment provides a controlled rolling and controlled cold rolling method for Q500 steel grade low-alloy structural steel bars, using a steel billet with a specification of 300 ⁇ 400mm as a raw material, and the chemical composition of the billet is the same as that of the billet in Example 1.
  • the chemical composition is the same.
  • the controlled rolling and controlled cold rolling method sequentially includes the following steps: heating, rolling, spray cooling, KOCKS rolling, and cooling to obtain a finished rolled material with a specification (diameter) of 50 mm. Specific steps are as follows:
  • (1) Heating Using a segmented heating process, the steel billet is placed in a heating furnace for heating.
  • the preheating temperature is 650°C
  • the heating temperature of the first stage is 1080°C
  • the heating temperature of the second stage is 1180°C
  • the soaking temperature is 1180°C.
  • Spray cooling the rolled piece obtained after final rolling is spray cooled; after cooling to 830°C, KOCKS rolling is carried out.
  • Table 5 lists the process parameters of spray cooling in this embodiment.
  • a water tank cooling channel with a spray ring diameter of ⁇ 110 is selected according to the size of the incoming rolling material (ie, the rolled piece obtained from final rolling).
  • the intensity of spray cooling is gradually reduced to prevent production failure caused by bending of the head of the rolled piece.
  • KOCKS rolling adopts three-roll rolling technology, which has the following advantages compared with traditional two-roll rolling technology:
  • the deformation efficiency of three-roll rolling is much higher than that of two-roll rolling.
  • the rolling force acts on the rolled piece from three sides to the center.
  • more deformation is converted into extension, and the rolling temperature rise is reduced, which is beneficial to the temperature-controlled rolling of the rolled piece;
  • the uniform deformation along the interface of the rolled piece can obtain a uniform metallographic structure and a consistent grain size.
  • Cooling step including the second spray cooling and cooling bed cooling.
  • the second spray cooling carry out the second spray cooling on the rolled piece after KOCKS rolling; the process parameters are shown in Table 7:
  • Cooling bed cooling Cooling the rods obtained after spray cooling, the temperature of the upper cooling bed is 540°C; the temperature of the lower cooling bed is 220-240°C.
  • the finally obtained bar size is ⁇ 50mm, and its properties are shown in Table 4. It can be seen from Table 4 that the impact of the steel bar obtained by the present invention through controlled rolling and controlled cooling has reached more than 100J at -40°C, meeting the GB/T1591-2018 standard on Q500 steel grades (three grades of Q500MC, Q500MD and Q500ME) performance requirements.
  • the bar prepared in this embodiment has a structure of sorbite (S) at the subcutaneous 5mm place in the same position, with a grain size of 9 grades, and the bar structure is uniform;
  • the grain size is grade 9, and the structure of the rod is uniform;
  • the structure at 25mm subcutaneous in the same part is F+P, the grain size is grade 9, and the structure of the rod is uniform.
  • a steel billet round billet with a specification of 390 mm is used as a raw material, and a finished product with a specification of 100 mm is obtained by rolling by a conventional rolling method;
  • the chemical composition (wt%) of the steel billet includes: C: 0.16; Si: 0.30; Mn: 1.40; P: 0.020; S: 0.008; Cr: 0.06; V: 0.06; Al: 0.030; N: 0.0090; the balance is iron and inevitable impurities, and CEV: 0.43.
  • the conventional rolling method includes the following steps in sequence: heating, rolling, and spray cooling to obtain a finished rolled material with a specification of 100 mm. Specific steps are as follows:
  • Heating Using a segmented heating process, the steel billet is placed in a heating furnace for heating.
  • the preheating temperature is 650°C
  • the heating temperature of the first stage is 1080°C
  • the heating temperature of the second stage is 1240°C
  • the soaking temperature is 1240°C.
  • Spray cooling the rolled piece obtained after final rolling is subjected to spray cooling.
  • Table 8 lists the process parameters of spray cooling in this embodiment.
  • Cooling bed cooling Cooling the rods obtained after spray cooling, the temperature of the upper cooling bed is 750°C; the temperature of the lower cooling bed is 300-350°C.
  • the final bar size is ⁇ 100mm, and its properties are shown in Table 4. It can be seen from Figure 5 that under the same chemical composition, the yield strength, tensile strength and impact energy of the bar prepared by the conventional method are relatively low although they meet the standard requirements.
  • the rod prepared in this embodiment has a structure of ferrite+pearlite (F+P) at 5 mm below the skin at the same site, with a grain size of 7 grades, and the rod structure is uniform (as shown in Figure 4);
  • the tissue at 15mm below the skin is F+P, the grain size is 6.5, and the bar structure is uniform (as shown in Figure 5);
  • the tissue at 25mm below the skin at the same site is F+P, the grain size is 6, and the bar The tissue is uniform (as shown in Figure 6).
  • the technical scheme of the present invention can significantly improve the yield strength and low-temperature impact performance of steel products with the same chemical composition.

Abstract

L'invention concerne une barre d'acier structurale faiblement alliée de qualité Q500 et un procédé de laminage régulé et de laminage à froid régulé afférant. La composition chimique (% en poids) de la barre comprend : C : 0,05 % à 0,09 %, Si : 0,20 % à 0,4 %, Mn : 1,00 % à 0,040 %, P : ≤ 0,030 % , S : ≤ 0,030 % ; Cr : ≤ 0,20 %, Ni : ≤ 0,20 %, Mo : ≤ 0,10 %, Cu : ≤ 0,15 %, V : 0,02 % à 0,050 %, Nb : ≤ 0,05 %, Ti : ≤ 0,02 %, B : ≤ 0,004 %, N : 0,005 % à 0,012 %, Al : 0,02 % à 0,04 %, CEV＝C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15≤0.45％. La température de laminage initiale du présent procédé est comprise entre 1000 et 1050 °C. L'utilisation du présent procédé permet d'obtenir l'uniformité de texture d'une pièce laminée.
PCT/CN2022/113683 2021-09-17 2022-08-19 Barre d'acier structurale faiblement alliée de qualité q500, et procédé de laminage régulé et de laminage à froid régulé afférant WO2023040581A1 (fr)

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CN114657349A (zh) * 2022-02-25 2022-06-24 南京钢铁股份有限公司 一种适用于冷加工的风电非调质钢棒材的制备方法

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