CN115418559B - High-strength and high-toughness hot rolled H-shaped steel for building and preparation method thereof - Google Patents

High-strength and high-toughness hot rolled H-shaped steel for building and preparation method thereof Download PDF

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CN115418559B
CN115418559B CN202210851313.2A CN202210851313A CN115418559B CN 115418559 B CN115418559 B CN 115418559B CN 202210851313 A CN202210851313 A CN 202210851313A CN 115418559 B CN115418559 B CN 115418559B
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equal
steel
cooling
flange
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CN115418559A (en
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赵培林
王建军
张佩
路峰
武文健
马佐仓
孔令坤
李超
刘洪银
李栋
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Shandong Iron and Steel Co Ltd
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Shandong Iron and Steel Co Ltd
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Priority to PCT/CN2022/133957 priority patent/WO2024016543A1/en
Priority to KR1020237042086A priority patent/KR20240013141A/en
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/02—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling heavy work, e.g. ingots, slabs, blooms, or billets, in which the cross-sectional form is unimportant ; Rolling combined with forging or pressing
    • B21B1/026—Rolling
    • 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
    • B21B1/08—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 structural sections, i.e. work of special cross-section, e.g. angle steel
    • B21B1/088—H- or I-sections
    • 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
    • B21B1/46—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 metal immediately subsequent to continuous casting
    • B21B1/463—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 metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
    • 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
    • B21B45/004—Heating the product
    • 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
    • B21B45/0209—Cooling devices, e.g. using gaseous coolants
    • 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
    • B21B45/0209—Cooling devices, e.g. using gaseous coolants
    • B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/111—Treating the molten metal by using protecting powders
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/36—Processes yielding slags of special composition
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • 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
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • 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
    • C22C33/06—Making ferrous alloys by melting using master 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
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • 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
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • 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
    • B21B45/0209—Cooling devices, e.g. using gaseous coolants
    • B21B2045/0212—Cooling devices, e.g. using gaseous coolants using gaseous coolants
    • 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
    • B21B45/0209—Cooling devices, e.g. using gaseous coolants
    • B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
    • B21B2045/0221—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for structural sections, e.g. H-beams
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C2007/0093—Duplex process; Two stage processes

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  • Manufacturing & Machinery (AREA)
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  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Metal Rolling (AREA)

Abstract

The application belongs to the technical field of steel smelting and rolling forming, and particularly relates to high-strength and high-toughness hot rolled H-shaped steel for buildings and a preparation method thereof. The hot rolled H-shaped steel comprises the following chemical components in percentage by weight: c:0.06 to 0.10; si: less than or equal to 0.25; mn:0.8 to 1.30; p is less than or equal to 0.015; s is less than or equal to 0.008; cu:0.15 to 0.25; cr:0.25 to 0.60; ni:0.10 to 0.19, V:0.01 to 0.03; al:0.01 to 0.03; RE: 0.009-0.019; as+Sn+Zn+Pb+Ca+Mg is less than or equal to 0.035, and N is less than or equal to 0.008; the total content of the O is less than or equal to 0.002, and the balance of Fe and unavoidable impurities. The application realizes the weight reduction of the building structural steel, has good comprehensive properties such as corrosion resistance, Z-direction performance, low temperature resistance and toughness, and completely meets the engineering requirements of the current assembled building structural steel.

Description

High-strength and high-toughness hot rolled H-shaped steel for building and preparation method thereof
Technical Field
The application belongs to the technical field of steel smelting and rolling forming, and particularly relates to high-strength and high-toughness hot rolled H-shaped steel for buildings and a preparation method thereof.
Background
With the gradual improvement of the requirements of the domestic construction engineering quality, the country puts higher demands on the development of the construction structural steel. Especially in the aspect of assembly type construction, the country is in a continuous stage-out policy, and the promotion is enhanced. The assembled building has the technical advantages of good anti-seismic performance, light dead weight, high construction speed, high industrialization degree, high component prefabrication rate and the like, the use of the steel structure meets the congenital assembly advantage, the construction period has larger advantages compared with the traditional construction period, the components in the assembled steel structure are mostly steel materials, the assembled building belongs to green environment-friendly building materials, and the assembled building has incomparable green environment-friendly advantage compared with concrete in the aspects of recycling and secondary utilization. The assembled building of our country is much lower than that of the developed countries abroad. Therefore, the national requirements are that the construction mode innovation is promoted according to the requirements of applicability, economy, safety, green and attractive appearance, the proportion of the assembled concrete building and the steel structure building in the newly built building is continuously improved, the performances and technical measures such as fire resistance and corrosion resistance of the steel structure building are perfected, the application of hot-rolled H-shaped steel, weather-resistant steel and fire-resistant steel is enlarged, and the comprehensive development of the key technology and related industries of the steel structure building is promoted.
The hot rolled H-shaped steel is used as a main material for building structures, and different working conditions put higher requirements on mechanical properties, corrosion resistance, fire resistance, structural stability and the like. The lamellar tearing resistance is an important index to ensure the safety and structural stability of the building structural steel. The lamellar tearing resistance steel is also called Z-direction steel, and mainly adopts the reduction of area Z of a steel plate thickness direction tensile test to evaluate lamellar tearing resistance. For steel materials having a thickness exceeding 15mm, it is generally necessary to examine the Z-direction lamellar tearing resistance as long as the structural member generates tensile force or fatigue stress in the plate thickness direction. For the common building structural steel, only the Z-direction performance index of the flange is needed, and the Z-direction performance index of the web is less. Therefore, in order to meet the requirements of steel for assembled buildings and high-rise buildings, the Z performances of the flanges and the webs which are important marks with excellent comprehensive lamellar tearing resistance simultaneously meet the requirements, and the difficulty is correspondingly improved along with the increase of the thickness.
Patent application CN113564480a discloses a heavy hot-rolled H-section steel with Z-direction properties and a method for producing the same, said hot-rolled H-section steel comprising the following chemical components: C. si, mn, nb, ti, N, B, als, the balance being iron and unavoidable impurities; the production method comprises the following steps: molten iron pretreatment, converter smelting, argon blowing refining, RH, special-shaped blank full-protection casting, stacking slow cooling, rolling and air cooling after rolling; according to the application, through reasonable component proportion and process control and through the cogging rolling, universal rolling and air cooling process after rolling, the quantity of second-oriented particles precipitated is regulated and controlled by utilizing a phase change, precipitation and fine crystal combination strengthening mode, and the content of granular bainite after rolling is between 10 and 20 percent, so that the heavy hot rolled H-shaped steel with the flange thickness of less than 80mm has excellent toughness and Z-direction performance, and the Z-direction performance is 65 to 80 percent. The strengthening is realized through the bainitic structure, but the bainitic is related to the cooling speed, so that the control difficulty of obtaining stable and uniform bainitic structure is high, and the bainitic steel has no obvious yield phenomenon.
Patent CN103334051B discloses a hot rolled H-section steel for construction with Z-direction property and a production method thereof. The application obtains the steel grade with excellent Z-direction performance and mechanical property by optimizing the smelting process and the rolling process and strictly controlling the product quality control means and the product production process. The H-shaped steel comprises the following chemical components in percentage by weight: c:0.06% -0.18%, si:0.10 to 0.25 percent of Mn:0.90% -1.60%, less than or equal to 0.10% V, less than or equal to 0.060% Nb, less than or equal to 0.030% Ti, and the balance iron and unavoidable impurities.
Patent number CN102418037B provides a hot rolled H-section steel with lamellar tearing resistance and a method for producing the same. According to the method for manufacturing H-shaped steel of the present application, si is added to molten steel during tapping to adjust Si in the molten steel to 0.10% -0.15% of the total weight of the molten steel, instead of Al deoxidation, and then at least one of Ti and Zr is added to the molten steel in a predetermined amount, wherein Si content required for the steel type can be supplemented during refining. The hot rolled H-shaped steel has lamellar tearing resistance and can meet the Z-direction performance requirement in a certain thickness direction.
In the prior art, simple microalloying is not beneficial to improving the surface quality of a casting blank, and severely restricts the improvement of toughness; meanwhile, the excessively high carbon content easily causes welding defects, causes large load of a rolling mill, bends and deflects rolled pieces, is not easy to control the size, has high equipment requirements, and causes lower comprehensive performance of H-shaped steel and lower size qualification rate of finished products.
In the current section steel production, control cooling is always a serious problem which puzzles uniform performance. Particularly for thick-specification products, the difference between the thickness dimensions of the flange and the web is large, the influence of a single cooling mode on the final performance is large, and meanwhile, the uniformity of Z-direction performance is influenced, so that the difference is large, and the safety of the structure is influenced. How to solve the problem, and considering the cost and the efficiency, is always one of the problems in the industry. Some enterprises use super-block cooling equipment, but the investment is large, and meanwhile, the economic aspect is not suitable for a single product variety with requirements. Therefore, for building structural steel products requiring overall Z-properties, special cooling equipment needs to be designed to meet the performance requirements.
Disclosure of Invention
In order to meet the requirements of steel for assembled building structures, the cooling system is specially designed according to the requirements. The hot rolled H-shaped steel for the building structure has the advantages of high strength and toughness and excellent lamellar tearing resistance with the yield strength reaching 420MPa level and the preparation method thereof. The steel product is suitable for the field of assembly type building structural engineering, and the web and the flange of the steel product have higher Z-direction performance and exceed the Z35 level. In order to realize excellent Z-direction performance of the flange and the web, the temperature uniformity control device of the flange and the web is added in combination with the component design of steel in the rolling process, so that good impact toughness at the low temperature of-20 ℃ is realized, the characteristics of excellent corrosion resistance, welding performance, low yield ratio and the like are realized, and the application requirements of hot rolled H-shaped steel materials in the steel building fields such as assembly type building structures in common areas and cold areas are met.
In order to achieve the above purpose, the technical scheme adopted by the application specifically requires the following steps:
the application provides 420 MPa-level hot rolled H-shaped steel for buildings, which comprises the following chemical components in percentage by weight: c:0.06 to 0.10; si: less than or equal to 0.25; mn:0.8 to 1.30; p is less than or equal to 0.015; s is less than or equal to 0.008; cu:0.15 to 0.25; cr:0.25 to 0.60; ni:0.10 to 0.19, V:0.01 to 0.03; al:0.01 to 0.03; RE: 0.009-0.019; as+Sn+Zn+Pb+Ca+Mg is less than or equal to 0.035. The balance of Fe and unavoidable impurities. Controlling the gas in the steel in the smelting process according to the weight percentage, wherein N is less than or equal to 0.008; and the T is less than or equal to 0.002.
In order to reduce the yield ratio, only a single microalloying design of vanadium-nitrogen alloy is adopted on the basis of low-carbon component design, meanwhile, the content is strictly controlled, the influence of precipitation strengthening on the yield strength is reduced, and finally the yield ratio of the H-shaped steel is less than or equal to 0.8. In order to improve the low-temperature-resistant toughness and strictly control the quantity and the size of inclusions, the content of other residual elements is controlled to be preferably less than or equal to 0.035 as+Sn+Zn+Pb+Ca+Mg on the basis of adding RE element to modify the inclusions.
The H-shaped steel for building with excellent comprehensive lamellar tearing resistance (Z-direction performance) 420MPa level steel structure provided by the application has the following functions by adding various chemical elements:
carbon: according to the requirement of the strength of 420MPa, the low-carbon component design can ensure that the building structural steel has certain low-temperature resistance, and simultaneously ensures that certain pearlite structure is generated to improve the yield ratio, thereby being suitable for the use requirement of the building structural steel. After the corrosion-resistant element is added, the abnormal structures such as Weissella and the like can be avoided due to the lower carbon content. For the profiled blank, transverse and longitudinal web cracks are easy to control, so that the carbon content is controlled to be 0.06% -0.10% in consideration of the tissue performance and smelting cost.
Silicon: the proper amount of Si is beneficial to the improvement of strength; too high Si content is liable to produce bainite and other structures; to avoid the generation of a large amount of Fe during reheating 2 SiO 4 Thus affecting the surface quality, the upper limit of the Si content is set to 0.25% or less, preferably 0.25% or less, more preferably 0.20% or less.
Manganese: the austenite stabilizing element can obviously increase the hardenability of the steel and improve the strength of the steel in a solid solution strengthening mode, but the excessive high content can easily cause segregation, and the difference between different parts is larger. The different parts of the thick structural section steel for the building structure have different structures, so that the upper limit of the Mn content is preferably set to be 1.30 percent in order to ensure the strength, reduce the hardenability and avoid a large number of abnormal structures. The Mn content in the H-shaped steel is controlled within the range of 0.8-1.30 percent by integrating various factors; to obtain 420 MPa-level strength, the range of 1.0 to 1.20% is preferable depending on the VN alloy addition amount.
Phosphorus: although the high phosphorus content is easy to improve the corrosion resistance, the excessively high phosphorus element is easy to deteriorate the low temperature resistance at the embrittled grain boundary, so that the lower the phosphorus control is, the better the effect is, and the low temperature toughness is improved; p is controlled below 0.015%;
sulfur: the sulfur element is too high to easily generate more sulfides such as MnS, a large number of strip-shaped MnS inclusions are generated at different parts of the section complex section steel, the low-temperature toughness is reduced, the corrosion resistance is not beneficial to being improved, the reduction of area is influenced, namely the lamellar tearing resistance of the steel is influenced, and therefore, the S is strictly controlled to be less than or equal to 0.008%;
copper: the corrosion resistance basic element of the steel is improved, cu can promote the steel to generate anode passivation, so that the corrosion rate of the steel is reduced, and the Cu is used as one of common elements of corrosion-resistant steel. The enrichment of the rust layer can greatly improve the protection performance of the rust layer; in order to achieve the effect of enriching Cu in the rust layer, cu is required to be more than 0.20%. However, too high Cu content is unfavorable for the welding performance of structural steel of the building, and copper embrittlement is easy to occur. In the process of producing the layer-loading-tearing-resistant performance section steel by adopting the special-shaped continuous casting blank, cracks are easily generated at the corners of the legs due to copper enrichment, the surface quality of the casting blank is seriously influenced, the plasticity of the steel is deteriorated, and the Cu content is controlled to be 0.15-0.25% on the basis of meeting the requirement of corrosion resistance of the assembled building structural section steel.
Nickel: the strength of the steel is improved through solid solution strengthening, the steel is also an effective element for improving low-temperature toughness, and meanwhile, the high-temperature plasticity of the steel in the continuous casting process can be improved, and the generation of defects on the surface of a casting blank is reduced. Ni has the effects of enlarging an austenite region and improving hardenability, and can refine pearlite sheets to refine pearlite to play a role of fine grain strengthening. The steel controls the Ni content to be in the range of 0.10 to 0.19 percent in combination with the Cu content control proportion.
Chromium: the elements which can improve the hardenability and the tempering stability and contribute to the strength improvement of the steel are also elements which can contribute to the corrosion resistance of the steel. The corrosion resistance of steel can be obviously improved when the alloy is matched with Cu and Ni elements. Under the condition of lower C content, the addition of a proper amount of Cr can improve the hardness and strength of steel and also can improve the corrosion resistance of the profile steel. Excessive addition will reduce the toughness, welding properties and flame cutting properties of the material. In terms of structure control, excessive Cr element affects the transformation of the steel structure, and generates abnormal structures such as bainite. Considering the aspects of strength and corrosion resistance improvement, the application controls the content of Cr:0.25 to 0.60 percent.
Vanadium: is one of the most commonly used and effective strengthening elements for microalloyed steels. Vanadium has the function of affecting the structure and the performance of steel by forming VN and V (CN), and mainly precipitates in ferrite of austenite grain boundaries to refine ferrite grains, thereby improving the strength and the low-temperature toughness of the material. Considering that the precipitation strengthening has a great influence on the yield strength and the strength is improved, the V is added at 0.01-0.03%.
Rare earth: rare earth purifies steel, and the modified impurities reduce pitting corrosion and intergranular corrosion. The solid solution rare earth in the steel improves the polarization resistance and the self-corrosion potential of the steel matrix, is beneficial to improving the corrosion resistance of the steel matrix, changes the structure of a rust layer, forms a rust layer with good adhesion and good compact corrosion resistance, and improves the corrosion resistance of the high-strength weathering steel. Considering that RE rare earth elements need to be added in proper amount for modifying inclusions such as MnS, the selection range is RE: 0.009-0.019%, RE rare earth element is a compound added element, and takes economic efficiency, cost performance and other factors into consideration, lanthanum and cerium series elements are mainly used in the application to play a role of spheroidizing inclusions.
Aluminum: al is added as a strong deoxidizing element in the preparation process of low-temperature steel. In order to ensure that the oxygen content in the steel is as low as possible, the inclusion content is reduced, and the redundant aluminum after deoxidation can also form AlN precipitates with nitrogen elements in the steel, austenite grains are refined in the heating and hot rolling processes. Therefore, the aluminum content is controlled to be in the range of 0.01 to 0.03% as the deoxidizing element and the fine crystal strengthening element.
As, sn, zn, pb, ca, mg: as a residual element in steel, the impact toughness at low temperature is greatly influenced, and the surface quality is also greatly influenced. Therefore, the content of the element which cannot be completely removed in the steel should be reduced as much as possible. The total amount of residual elements is controlled within the range of As+Sn+Zn+Pb+Ca+Mg being less than or equal to 0.035 by combining production practice, equipment capability and cost control.
Nitrogen: the N content is too high, so that the quality defect of the casting blank is easy to be induced; at the same time, VN alloying effect is ensured, so the nitrogen content is required to be less than 0.008 percent.
Oxygen: in order to avoid the formation of large-grained oxide inclusions and to deteriorate the toughness and plasticity of the steel, the application requires a total oxygen content T..ltoreq.O.ltoreq.0.0020%.
The H-shaped steel product has excellent comprehensive mechanical properties, the yield strength is more than or equal to 420MPa, the tensile strength is more than or equal to 520MPa, and the elongation is more than or equal to 19%; the longitudinal impact energy at the temperature of minus 20 ℃ is more than or equal to 50J, and is suitable for building structures in areas with low temperature. The Z-directional performance of the web plate and the flange is excellent, and the area shrinkage is more than or equal to 60 percent.
The preparation method of the hot rolled H-shaped steel with excellent lamellar tearing resistance suitable for the application of building structures in different areas mainly comprises the following steps: molten iron pretreatment, converter smelting, LF refining, RH refining, billet surface defect cleaning, special-shaped continuous casting billet casting, billet step-by-step heating furnace reheating, high-pressure water descaling, temperature control rolling, controlled cooling, low-temperature straightening, fixed-length sawing and collecting stacking.
Molten iron and scrap steel are smelted, refined and continuously cast in a converter and a refining furnace (LF+RH equipment) to obtain a special-shaped continuous casting blank, and the surface is subjected to defect detection and cleaning and then enters a rolling forming process. Firstly, a billet enters a step heating furnace for reheating to obtain an austenite structure with proper size, and is rolled into a material after rough rolling and finish rolling, and the rolling process is controlled to be rolled and cooled. It should be noted that the precise temperature control is performed at the last pass of finish rolling, and the temperatures of the upper and lower legs of the H-shaped steel and the upper and lower sides of the flange are basically consistent through a developed special cooling device (see a cooling device diagram of fig. 2), so that the consistency of the Z-direction performance of the flange and the web under the condition of uniform organization is ensured, and the structural stability and the safety of the assembled building structure when the product is used are ensured.
The main process of rolling and cooling control in the rolling process comprises the following steps: the heating temperature is controlled between 1250 ℃ and 1300 ℃, the temperature of the final rough rolling pass is 1150 ℃ to 1050 ℃ according to different sizes, the accumulated deformation rate is 40% -60%, and the rest is completed in the finish rolling stage. And (3) performing three-frame finish rolling after rough rolling, wherein the finish rolling temperature is precisely controlled between 800 ℃ and 850 ℃, so that an austenite structure is completely transformed into pearlite and ferrite, and fine-grain controlled rolling is realized. Because the temperature difference of 30-50 ℃ exists between the upper leg flange and the lower leg flange of the H-shaped steel and the upper side and the lower side of the web plate, cooling control is performed after the final pass of finish rolling is performed out of the rolling mill, cooling is performed by using designed cooling equipment to perform accurate control cooling of spraying water to the lower leg and the web plate through nozzles, and corresponding water flow control is performed according to the detected temperature difference. The temperature difference of the same parts of the upper leg flange and the lower leg flange is reduced to be within 10 ℃ after cooling, and the upper surface and the lower surface of the web plate are reduced to be within 5 ℃, so that the integral Z-direction performance of the upper leg flange and the lower leg flange of the H-shaped steel is basically consistent with that of the web plate. And after finish rolling, the rolled piece passes through the conveying roller way, and the cooling rate is controlled by adopting a heat preservation cover according to the ambient temperature, so that the influence on the final performance caused by larger fluctuation of the ambient temperature in different seasons is avoided. And (3) after the product is discharged from the finishing mill, naturally cooling the product in a cooling bed, and straightening the product in a straightener after the temperature of the product is reduced to below 100 ℃. The thickness range of the flange of the finished product specification of the rolled material is 15-50mm. And sampling at the middle parts of the flange part and the web plate of the H-shaped steel to detect the mechanical properties. The Z-direction stretching section shrinkage deviation of the flanges and the webs of the H-shaped steel produced by the process is controlled below 5 percent.
Preferably, the 420 MPa-grade hot rolled H-shaped steel for the fabricated building with excellent lamellar tearing resistance, the preparation method and specific process control thereof provided by the application specifically comprise the following aspects:
1 smelting process
1) Converter smelting
The converter is controlled according to basic operation, and main procedures comprise strictly controlling the content of residual elements such as sulfur, arsenic and the like in the molten iron of the blast furnace and carrying out molten iron quality optimization treatment, wherein both arsenic and tin are less than 0.008%; the final slag alkalinity of the converter is in the range of 2.1-3.9, slag stopping tapping is adopted, and aluminum-manganese-iron deoxidization alloying is adopted in the tapping process. And adding deoxidizing agent, ferrosilicon, manganese metal, vanadium-nitrogen alloy, ferroniobium alloy, nickel plate and the like in batches in the tapping process, and finally, enabling the components of the converter to meet the requirement of an internal control target.
2) Refining LF+RH duplex control
The refining process adopts LF+RH duplex control gas and inclusion. LF adopts calcium carbide, calcium barium silicate and aluminum particles to regulate slag, and white slag or yellow and white slag is needed to be formed on top slag before the slag leaves a station. After the primary sample is taken in the station, oxygen is fixed and controlled at the concentration of [ O ] to be less than or equal to 20ppm; RE is added before the calcium wire is fed, bottom blowing nitrogen is carried out in the whole process according to the process requirement, the soft blowing time is not less than 20 minutes, the refining period is not less than 30 minutes, the molten steel temperature at the LF refining finishing moment is controlled at 1600-1620 ℃, the molten steel temperature is improved, so as to counteract the temperature drop of the molten steel at the RH processing moment, and the temperature rise of the molten steel at the RH processing moment by adopting the method of chemical heat generation by aluminum addition is strictly forbidden.
The RH refining adopts the treatment mode, the circulation time is more than 15min, the pure degassing time is more than 5min, after the treatment is finished, 200-250 m of calcium aluminum wires are fed into each furnace, the soft blowing time is not less than 10 min, and the RH smelting period is controlled to be 40-50 min.
The whole-process protection casting refers to adopting a long water gap from a ladle to a tundish and performing argon sealing protection; the tundish is covered by adopting a covering agent and carbonized rice hulls; the tundish to the crystallizer adopts a submerged nozzle and adopts argon seal protection; the liquid level of the crystallizer adopts peritectic steel covering slag; preferably, the peritectic steel covering slag comprises the components of 25% or less of SiO and 35% or less of CaO and 45% or less, 1.90% or less of MgO and 3.00% or less, and 3.00% or less of Al by weight 2 O 3 ≤4.00％。
3) Continuous casting
The continuous casting process adopts a full protection casting process, uses a large ladle of long water gap, and increases the control of a sealing ring; the tundish adopts stopper Bao Jiaozhu molten steel; the drawing speed of the special-shaped continuous casting blank is 1.0-1.2 m/min for improving the efficiency; the superheat degree is controlled below 20-30 ℃ to prevent the blockage of the water gap; and casting the smelted molten steel into 3 dimension specifications of the special-shaped blank with the near-net-shaped section, and carrying out slow cooling treatment in a heat preservation pit or a sand pit or by using a heat preservation felt after casting and molding the special-shaped blank for avoiding surface cracks due to the large alloy quantity.
2 Rolling Process
1) Heating
The blank is heated uniformly by austenitizing in a heating furnace, the temperature in the heating and soaking stages is controlled between 1250 and 1300 ℃, the heating time is between 90 and 120 minutes, and then the blank is taken out of the furnace to be rolled. Heating at high temperature for short time, and controlling homogenization and refinement of austenite.
2) Controlled rolling and controlled cooling
The controlled rolling/cooling process is adopted in a large production line. The rough rolling process realizes grooved rolling with the shape as the main part, and the rolling pass is less than 9 times; and performing performance control rolling in the finish rolling process, wherein the rolling pass is less than 7. The finish rolling temperature is controlled between 800 ℃ and 850 ℃. The cooling track of the cooling bed keeps the temperature above 400 ℃, and the product is intensively and slowly cooled in the cooling bed, so that the final performance is prevented from being influenced by the excessive cooling speed. And (3) reducing the temperature of the product to 200-300 ℃ and straightening the product in a straightener, so as to ensure the integrity of the primary oxidized iron sheet on the surface.
The application provides a cooling device for improving comprehensive performance, wherein the rolling process adopts a specially designed cooling device to comprehensively cool a web plate and flanges, the cooling device is arranged behind a finishing mill, the cooling device comprises a plurality of cooling liquid pipelines 1 which are distributed at intervals and a plurality of cooling air pipelines 2 which are distributed at intervals, the cooling liquid pipelines 1 are used for cooling flanges, are arranged below a lower flange 6 of hot rolled H-shaped steel and comprise a first flange pipeline 4 parallel to the web plate and two groups of second flange pipelines which are vertical to and communicated with the first flange pipeline 4, and each group of second flange pipelines corresponds to one flange; each group of second flange pipelines comprises two parallel lower flange pipelines 5, a plurality of nozzles 3 are arranged on the surface of each lower flange pipeline 5 opposite to each lower flange 6 and are used for cooling flanges, and the lower flanges 6 of H-shaped steel are arranged between the two parallel lower flange pipelines 5; the cold air pipeline 2 is used for cooling the web plate, is convex, is arranged between the lower flange 6 and the web plate 8, and is parallel to and close to the web plate 8, and a plurality of nozzles 3 are arranged on the cold air pipeline and are used for cooling the web plate 8. The shape of the cold air duct matches the shape formed by the lower flange and the web. The cooling rate can be controlled depending on the web and flange thickness (see fig. 1). The cooling device is arranged at the rear of the finishing mill, and is started in the last rolling pass, and the installation flange and the web are separated for cooling. In fig. 1, coolant pipes numbered 1 are used for flange cooling; due to the large thickness of the flange, cooling water or other cooling media are adopted for cooling according to the cooling speed. The flow of the cooling liquid is regulated through the nozzle 3 after the temperature difference measurement is carried out according to the online temperature measuring device of the upper flange 7 and the lower flange 6. Because the web thickness is thinner than the flange, the need can be satisfied by using cooling air. The cold air duct numbered 2 is used for web cooling; the temperature difference between the upper part and the lower part of the web is smaller, so that the cooling is realized by properly adjusting the flow of the cooling air of the nozzle 3 according to the requirement. Through the device, the temperature difference of the upper leg flange and the lower leg flange is within the range of 5-10 ℃, and the temperature difference of the web plate is within the range of 3-6 ℃. Thereby guaranteeing the uniformity of the structure and improving the Z-direction performance of the web plate and the flange of the structural steel of the building. The equipment is matched with the vanadium microalloying design, so that the performance requirement of the final hot rolled H-shaped steel can be met, and meanwhile, the Z-direction performance of the web plate and the flange can reach a higher level.
3) Finishing process
After the product is off-line, carrying out surface and size finishing treatment; in order to ensure the real and accurate performance of the material, the sample is sampled and analyzed in the finishing procedure to analyze the performance of the product.
Compared with the prior art, the application has the advantages that:
(1) The low carbon + micro VN alloying + RE component design is simple and efficient compared with other alloying, and the incidence of casting blank defects is reduced; (2) The control of low residual elements and impurity elements of molten steel is beneficial to improving the plasticity and low-temperature toughness of steel; (3) A certain amount of RE element is added, and the inclusion in the steel is tiny, so that the anti-lamellar performance of the flange and the web is improved; (4) The Al deoxidation process is realized by adopting the single-side casting control technology of the special-shaped blank, the purity of molten steel is improved, and the problem of blockage in the casting process of a long nozzle is avoided. (5) The web flange uniform cooling process is realized through the designed special water spraying device, the overall tissue uniformity of the web flange is improved, the lamellar tearing resistance performance is synchronously controlled and improved, and the comprehensive toughness performance of the H-shaped steel is integrally improved. (6) Through the process, the yield strength of the prepared H-shaped steel reaches over 420MPa, the weight reduction of the building structural steel is realized, and meanwhile, the H-shaped steel has good corrosion resistance, Z-direction performance, low temperature toughness and other comprehensive properties, and the engineering requirements of the current fabricated building structural steel are completely met.
Drawings
FIG. 1 (a) is a plan view of a cooling arrangement for H-section steel production according to the present application;
FIG. 1 (b) is a perspective view of the cooling arrangement of the H-section steel production of the present application;
FIG. 2 (a) is a microstructure of the upper leg of the H-shaped steel obtained in example 1 of the present application;
FIG. 2 (b) is a microstructure of the lower leg of the H-shaped steel obtained in example 1 of the present application;
FIG. 2 (c) is a microstructure of the flange of the H-beam obtained in example 1 of the present application;
FIG. 3 (a) is a microstructure of the upper leg of the H-shaped steel obtained in example 6 of the present application;
FIG. 3 (b) is a microstructure of the lower leg of the H-shaped steel obtained in example 6 of the present application;
FIG. 3 (c) is a microstructure of the flange of H-beam obtained in example 6 of the present application;
reference numerals:
1. the cooling liquid pipeline, 2, the cold air pipeline, 3, the nozzle, 4, the first flange pipeline, 5, the lower flange pipeline, 6, the lower flange, 7, the upper flange, 8 and the web plate.
Detailed Description
The application will be further illustrated with reference to specific examples.
The present application will be described in detail below:
table 1 is a listing of chemical components of each example and comparative example of the present application;
table 2 is a list of the main process parameters for each example and comparative example of the present application;
table 3 shows a list of performance tests for each of the examples and comparative examples of the present application.
The production of each embodiment of the application is carried out according to the following steps:
1) Preferably, low-phosphorus low-sulfur molten iron with low residual elements is smelted in a converter and then enters LF+RH duplex for component and inclusion control; the molten steel temperature at the LF refining finishing moment is controlled to 1600-1620 ℃, and the molten steel temperature is increased to offset the temperature drop of the molten steel at the RH processing moment, and the heating up by a method of generating chemical heat by adding aluminum is strictly forbidden at the RH processing moment; the RH refining adopts the treatment mode, the circulation time is more than 15min, the pure degassing time is more than 5min, after the treatment is finished, 200-250 m of calcium aluminum wires are fed into each furnace, the soft blowing time is not less than 10 min, and the RH smelting period is controlled to be 40-50 min.
Finally, continuously casting into a special-shaped blank, and dividing the special-shaped blank into three blank types according to different flange thicknesses. The residual elements of the molten iron are strictly controlled to be as+Sn+Zn+Pb+Ca+Mg which is less than or equal to 0.035; the casting process controls the casting superheat degree to be less than 20 ℃, and optionally one value is selected as constant blank drawing speed within the blank drawing speed of 1.0-1.18 m/min, and the straightening temperature is not lower than 850 ℃.
2) And a rolling procedure, wherein the blank is reheated in a heating furnace at 1250-1300 ℃ for 90-120 min, and then is discharged from the furnace for rolling. A controlled rolling/controlled cooling process is employed. The rolling pass of the BD rough rolling procedure is less than 9; the rolling pass of the finish rolling TM process is less than 7. The finish rolling temperature is controlled between 800 ℃ and 850 ℃. The cooling track of the cooling bed keeps the temperature of more than 400 ℃, and the product is intensively and slowly cooled in the cooling bed for more than 15 minutes. And (5) reducing the temperature of the product to 200-300 ℃ and straightening the product in a straightener.
3) Finishing, namely finishing the surface and the size of the product after the product is off line; and (5) performing sample sampling in the finishing procedure to analyze the product performance.
Table 1 chemical composition (wt.%) of each example and comparative example of the present application
The main technological parameters of refining are shown in Table 2
Table 2 major refining process parameters
Specific process parameters of the continuous casting process are shown in Table 3.
TABLE 3 Process parameters for continuous casting process
Table 3 is a list of the main process parameters for each example and comparative example of the present application;
TABLE 4 main process parameters
Table 5 shows a list of performance tests for each of the examples and comparative examples of the present application.
Table 5: recording meter for mechanical properties of rolled material
The method comprises the steps of performing performance test on test product samples, wherein the sampling position of a sample for mechanical properties is 1/3 of the position from the edge part to the center part of an H-shaped steel flange, and the sampling position of a web is in the middle part, and the reference standard is BS EN ISO 377-1997, namely the sampling position and preparation of a mechanical property test sample; test methods of yield strength, tensile strength and elongation refer to the standard ISO 6892-1-2009 method for tensile test of metallic Material at Room temperature; impact energy test method reference standard ISO148-1 Charpy pendulum impact test for metallic materials, results are shown in Table 5. Through comparison, the Z-direction performance of the flange and the web of the H-shaped steel produced by the preparation method related to the patent is superior to that of the products in the current patent.
The application may be practiced without these specific details, using any knowledge known in the art.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present application and are not limiting. Although the present application has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present application, which is intended to be covered by the appended claims.

Claims (7)

1. The hot rolled H-shaped steel for the high-strength and high-toughness building is characterized by comprising the following chemical components in percentage by weight: c:0.06 to 0.10 percent; si: less than or equal to 0.25 percent; mn:0.8 to 1.30 percent; p is less than or equal to 0.015 percent; s is less than or equal to 0.008 percent; cu:0.15 to 0.25 percent; cr:0.25 to 0.60 percent; ni:0.10 to 0.19 percent, V:0.01 to 0.03 percent; al:0.01 to 0.03 percent; RE: 0.009-0.019%; as+Sn+Zn+Pb+Ca+Mg is less than or equal to 0.035%, and N is less than or equal to 0.008%; the total content of [ O ] is less than or equal to 0.002%, and the balance is Fe and unavoidable impurities;
the preparation method of the high-strength and high-toughness hot rolled H-shaped steel for the building comprises the following steps:
1) The smelting process sequentially comprises the following steps:
smelting in a converter;
LF+RH refining: controlling the temperature of molten steel at 1600-1620 ℃ at the end time of LF refining; the RH refining circulation time is more than 15min, and the smelting period is controlled to be 40-50 min;
continuous casting;
2) The rolling process sequentially comprises the following steps:
heating: the temperature in the heating and soaking stage is controlled between 1250 and 1300 ℃, the heating time is between 90 and 120 minutes, and then the steel is taken out of the furnace for rolling;
controlled rolling and controlled cooling: the finish rolling temperature is controlled at 800-850 ℃, the cooling track of the cooling bed is kept at a temperature above 400 ℃, and the product is intensively and slowly cooled in the cooling bed; the temperature of the product is reduced to 200-300 ℃ for straightening,
the web and the flange are cooled separately by adopting a cooling device in the rolling process, and the rolling process is started in the last pass;
the cooling device is arranged behind the finishing mill and comprises a plurality of cooling liquid pipelines which are distributed at intervals and a plurality of cooling air pipelines which are distributed at intervals;
the cooling liquid pipeline is used for cooling the flange, is arranged below the lower flange of the hot rolled H-shaped steel, and comprises a first flange pipeline parallel to the web plate and two groups of second flange pipelines perpendicular to and communicated with the first flange pipeline, and each group of second flange pipelines corresponds to one flange;
the second flange pipelines of each group comprise two parallel lower flange pipelines, a plurality of nozzles are arranged on the surfaces of the lower flange pipelines, which are opposite to the lower flange, and are used for cooling the flanges, and the lower flanges of the H-shaped steel are arranged between the two parallel lower flange pipelines;
the cold air pipeline is used for cooling the web plate, is convex, is arranged between the lower flange and the web plate, and is parallel to and close to the web plate, and a plurality of nozzles are arranged on the cold air pipeline and are used for cooling the web plate;
3) And (3) finishing.
2. The hot rolled H-section steel according to claim 1, wherein the yield ratio of the hot rolled H-section steel is not more than 0.8, the yield strength is not less than 420MPa, the tensile strength is not less than 520MPa, and the elongation is not less than 19%; the longitudinal impact power at the temperature of minus 20 ℃ is more than or equal to 50J, and the area shrinkage rate is more than or equal to 60 percent.
3. The hot rolled H-shaped steel according to claim 1, wherein the arsenic and tin contents in the converter smelting in the step 1) are less than 0.008%, the final slag alkalinity of the converter is in the range of 2.1-3.9, slag-stopping tapping is adopted, and aluminum-manganese-iron deoxidization alloying is adopted in the tapping process.
4. The hot rolled H-section steel according to claim 1, wherein in the step 1) LF refining, RE is added before feeding a calcium line, the soft blowing time is not less than 20 minutes, and the refining period is not less than 30 minutes;
the RH refining pure degassing time is more than 5 minutes, after the treatment is finished, 200-250 m calcium aluminum wires are fed into each furnace, and the soft blowing time is not less than 10 minutes;
the whole process of casting is protected,the tundish is covered by adopting a covering agent and carbonized rice hulls; the tundish to the crystallizer adopts a submerged nozzle and adopts argon seal protection; the liquid level of the crystallizer adopts peritectic steel covering slag; wherein, the compositions of the peritectic steel covering slag are that SiO is more than or equal to 25% and less than or equal to 35%, caO is more than or equal to 35% and less than or equal to 45%, mgO is more than or equal to 1.90% and less than or equal to 3.00%, al is more than or equal to 3.00% according to the weight percentage 2 O 3 ≤4.00％。
5. The hot rolled H-section steel according to claim 1, wherein the continuous casting process of step 1) adopts a full protection casting process, and the tundish adopts stopper Bao Jiaozhu molten steel; the drawing speed of the special-shaped continuous casting blank is 1.0-1.2 m/min; the superheat degree is controlled at 20-30 ℃.
6. The hot rolled H-shaped steel according to claim 1, wherein the step 2) further comprises a rough rolling process, the grooved rolling with the main shape is realized, the temperature of the rough rolling last pass is 1150-1050 ℃, the accumulated deformation rate is 40% -60%, and the rolling pass is less than 9 passes;
in the finish rolling process, performance control rolling is carried out in the finish rolling process, and the rolling pass is less than 7.
7. The hot rolled H-section steel according to claim 1, wherein the temperature difference of the same parts of the upper and lower flanges after cooling is reduced to within 10 ℃, the upper and lower surfaces of the web are reduced to within 5 ℃, and the deviation of the Z-direction stretching reduction of area of the H-section steel flange and the web is controlled to be below 5%.
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