CN117144081B - Rolling method of hot rolled H-shaped steel for Nb-containing low temperature resistant structure - Google Patents

Rolling method of hot rolled H-shaped steel for Nb-containing low temperature resistant structure Download PDF

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CN117144081B
CN117144081B CN202311415311.XA CN202311415311A CN117144081B CN 117144081 B CN117144081 B CN 117144081B CN 202311415311 A CN202311415311 A CN 202311415311A CN 117144081 B CN117144081 B CN 117144081B
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agent
powder
temperature
desilication
cooling
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CN117144081A (en
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辛本龙
翟兵
韩海生
王玉文
张忠良
石孜江
王坤
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Jinding Casting Co ltd
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    • 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
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/35—Blowing from above and through the bath
    • 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
    • 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
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D123/00—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers
    • C09D123/02—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
    • C09D123/10—Homopolymers or copolymers of propene
    • C09D123/12—Polypropene
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    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/03—Powdery paints
    • C09D5/033—Powdery paints characterised by the 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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • 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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/04—Removing impurities other than carbon, phosphorus or sulfur
    • 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
    • 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
    • C21C7/064—Dephosphorising; Desulfurising
    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—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
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C08K2003/2237—Oxides; Hydroxides of metals of titanium
    • C08K2003/2241—Titanium dioxide
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
    • C08K2003/3045—Sulfates
    • 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
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention discloses a rolling method of hot rolled H-shaped steel for a Nb-containing low temperature resistant structure, which comprises the following steps: molten iron pretreatment, preparation of a graphene additive, converter smelting, LF external refining, profiled blank continuous casting, profiled blank heating, rolling and cooling, wherein water cooling is adopted for cooling, the cooling speed is controlled to be 10-20 ℃/s, the final cooling temperature is controlled to be below 100 ℃, a straightener is used for straightening, powder coating is coated on the surface of the straightened steel, and after ultraviolet irradiation is carried out for 2 hours, sizing and bundling are carried out. The powder coating has good toughness and low-temperature performance, can further improve the low-temperature resistance of the steel, and the graphene additive can improve the corrosion resistance of the steel and has longer service life.

Description

Rolling method of hot rolled H-shaped steel for Nb-containing low temperature resistant structure
Technical Field
The invention belongs to the technical field of steel processing, and particularly relates to a rolling method of hot rolled H-shaped steel for a Nb-containing low-temperature-resistant structure.
Background
In recent years, with the continuous development of oil and gas resources in alpine regions, the market demand for hot rolled H-shaped steel for low temperature structures is increasing. The hot rolled H-shaped steel for the low temperature structure is often applied to a working environment with very bad environmental conditions, and besides the influence of gravity load, wind load, wave load, river load, ice load, earthquake load and the like are considered.
The increase of the carbon content has adverse effects on the toughness, plasticity and welding performance of the steel, and the carbon content is generally controlled to be less than or equal to 0.09%; manganese can reduce transformation temperature of austenite to ferrite, inhibit formation of proeutectoid ferrite and play a role of solid solution strengthening, but too high manganese content can deteriorate toughness of a heat affected zone and reduce welding performance; niobium has remarkable grain refinement effect, mainly is characterized in that the growth of austenite grains is inhibited in the reheating process, and the strength is improved under the condition of not losing toughness; adding a small amount of titanium, combining with N, precipitating and separating out TiN at the grain boundary, inhibiting the growth of austenite grains and the formation of eutectoid ferrite at the austenite grain boundary, and playing a role in strengthening; chromium can improve strength and hardenability; nickel can improve the low-temperature impact toughness of the steel plate; phosphorus is easy to segregate, and the welding performance and low-temperature impact toughness of bridge steel for low temperature are deteriorated; sulfur affects the low temperature impact toughness of the steel, increases anisotropy, and requires strict control of phosphorus and sulfur content in production. In order to improve the comprehensive performance of the bridge steel, nb-Ti-Cr-Ni is added in a compounding way so as to obtain a better micro-alloying treatment effect than that of adding a single element.
Patent document CN112522601a (hereinafter referred to as document 1) discloses a process method for producing Nb-containing low-cost small-medium-specification hot-rolled H-section steel, which reduces the production cost of the hot-rolled H-section steel by reasonable component proportion and optimizing the production process method, but the impact energy of the obtained hot-rolled H-section steel at 20 ℃ can only meet 34J or more, and is not suitable for application in alpine regions.
Although the corrosion effect of steel is small when the steel is used in a low-temperature area, the corrosion problem also exists, the corrosion effect is particularly important to the steel use along with the use time, but a protective layer is generally plated on the surface of metal in the steel processing process, but the plating layer is easily separated from a metal body in a low-temperature environment, and the protective effect is lost.
Disclosure of Invention
The invention aims to provide a rolling method of hot rolled H-shaped steel for a Nb-containing low-temperature-resistant structure, which aims to solve the problems in the prior art.
In order to achieve the above purpose, the present invention provides the following technical solutions: a rolling method of hot rolled H-shaped steel for Nb-containing low temperature resistant structure comprises the following steps:
and (3) molten iron pretreatment: including desulfurization, desilication and dephosphorization;
preparation of graphene additive: dispersing graphene with the particle size of 2-5nm into absolute ethyl alcohol, irradiating for 1-2h under an ultraviolet lamp to obtain a mixed solution, adding Nb powder into the mixed solution, heating for 2h under the condition of microwave 550W, stirring and mixing for 2-4h at 1000rpm to obtain a mixed solution, centrifuging the mixed solution at the rotating speed of 5000rpm for 1h by using a centrifuge to obtain bottom powder, then placing the powder into a vacuum drying furnace, drying for 24h at 100-130 ℃, then flushing hydrogen for 30min at 220 ℃ to obtain powder, and adding a smelting additive into the powder for grinding to obtain a graphene additive;
smelting in a converter: smelting by adopting a top-bottom combined blown converter, and adding molten iron, a metal raw material and a graphene additive into a furnace body for smelting;
LF external refining: fully stirring and dissolving slag in the refining process to prepare yellow and white slag;
continuous casting of the special-shaped blank: adopting immersed flat nozzle full protection casting;
heating the special-shaped blank: heating the special-shaped continuous casting blank in a hot furnace, wherein the heating temperature of the casting blank is 1200-1400 ℃, the heat preservation time is 2-4 hours, and descaling by using high-pressure water after discharging;
rolling and cooling, wherein the cooling adopts water cooling, the cooling speed is controlled to be 10-20 ℃/s, the final cooling temperature is controlled to be below 100 ℃, and straightening is carried out by using a straightener;
and (3) coating powder coating on the surface of the straightened steel, and cutting to a fixed size and bundling after irradiating for 2 hours.
Preferably, the H-shaped steel comprises the following chemical components in parts by weight: 0.0610-0.0910% of C, 0.3100-0.6520% of Si, 1.2200-1.8320% of Mn, 0.2100-0.2520% of Cr, 0.0320-0.0480% of Nb, 0.1120-0.1620% of Ti, 0.0008-0.0010% of Ce, less than or equal to 0.020% of P, less than or equal to 0.020% of S, and the balance of iron and unavoidable impurities.
In any of the above schemes, preferably, the chemical components of the H-shaped steel are as follows by weight: 0.0750% of C, 0.4500% of Si, 1.5500% of Mn, 0.2300% of Cr, 0.04100% of Nb, 0.1340% of Ti, 0.0009% of Ce, 0.015% of P, 0.015% of S, and the balance of iron and unavoidable impurities, wherein the mass fraction is 100% in total.
In any of the above schemes, preferably, the powder coating comprises polypropylene degradation resin, polyester resin, curing agent, brightening agent, leveling agent, benzoin, titanium pigment and barium sulfate, wherein the mass ratio of the polypropylene degradation resin to the polyester resin is 3:2-27.
In any of the above schemes, preferably, the preparation process of the powder coating comprises the steps of adding polypropylene degradation resin, polyester resin, curing agent, brightening agent, leveling agent, benzoin, titanium pigment, barium sulfate and pigment into a mixer, mixing at normal temperature, extruding through an extruding machine, tabletting through a tablet press, grinding into powder, and sieving with a 100-200 mesh sieve to obtain the powder coating.
In any of the above schemes, preferably, the desulfurization process comprises adding a desulfurizing agent into molten iron, stirring at 20rpm for 30min, heating at 5 ℃/min, stopping stirring when heating to 60 ℃, heating at 10 ℃/min, stopping heating until 120 ℃, maintaining at the temperature for 20min, and then passing the desulfurized molten iron through a desulfurization filter element to complete desulfurization.
In any of the above schemes, it is preferable that the desulfurizing agent comprises 100-120 parts by weight of CaO, 10-15 parts by weight of SiO2, 1-5 parts by weight of Al and 0.5-1 parts by weight of BaO.
In any of the above schemes, it is preferable that the desulfurization filter element comprises 8-11% of active calcium carbonate, 48-55% of calcium oxide, 0.3-0.7% of magnesium oxide, 17-22% of calcium carbide, 2.5-3.5% of barium oxide, 4-6% of powdery sodium silicate, 4.5-7% of silicon dioxide and 4-8% of gypsum powder, the above raw materials are mixed, added with water, molded and then placed into a puffing box, and hot air at 150-200 ℃ is introduced for 2-10 minutes under 9-12 atmospheric pressures to form porous solid, thus the desulfurization filter element is obtained.
In any of the above schemes, preferably, the dephosphorization process comprises adding dephosphorization agent into molten iron, standing for 30-60min, stirring for 15-20min at 30rpm, and standing for 30min to complete dephosphorization, wherein the dephosphorization agent comprises ferrous sulfate, magnesium chloride and polyaluminium chloride according to the mass ratio: 1-2:6-7:3-4.
In any of the above schemes, preferably, the desilication process comprises the steps of adding desilication agent into an empty ladle of a hot metal ladle in advance, then filling molten iron into the hot metal ladle, completing desilication treatment after a blast furnace receives iron and during steelmaking and iron folding, wherein the addition amount of the desilication agent is 40-60kg per ton of molten iron, the desilication agent comprises 22-48% of blast furnace dust, 22-28% of fluorite powder and the balance of converter dust.
The invention has the technical effects and advantages that: according to the rolling method of the hot rolled H-shaped steel for the Nb-containing low temperature resistant structure, ce is added into the raw materials, the existence of the Ce reduces the size of ferrite, the morphology of pearlite is improved, and the Ce can also enable Al to be added into the raw materials 2 O 3 And MnS+Ti 4 C 2 S 2 The inclusions are respectively changed into ellipsoids CeAlO 3 And spherical Ce 2 O 2 S+Ti 4 C 2 S 2 Composite inclusion is easier to remove, and formed Ce 2 O 2 S inclusion is fine, the steel microstructure can be refined as heterogeneous nucleation points, the addition amount of Ce is 0.0008-0.0010%, the inclusion is effectively modified to form fine Ce-containing rare earth inclusion, the fracture resistance of the steel in a low-temperature environment is enhanced, the optimal low-temperature toughness is obtained, and the surface of the steel is coated with powder coating, wherein the powder coating comprises polypropylene degradation resin, polyester resin, curing agent, polishing agent, flatting agent, benzoin, titanium pigment and barium sulfate, and the powder coating has good toughness and low-temperature resistance and can further improve the low-temperature resistance of the steel; the graphene additive is added in the smelting process, so that graphene is distributed in steel instead of being attached to the surface to form a protective layer, the protective layer can fall off, the graphene is distributed in the steel and cannot appear, and the graphene is distributed in the steel, so that the corrosion resistance of the steel can be improved, and the service life of the steel is longer.
Detailed Description
The following description will clearly and fully describe the technical solutions of the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
A rolling method of hot rolled H-shaped steel for Nb-containing low temperature resistant structure comprises the following steps:
and (3) molten iron pretreatment: including desulfurization, desilication and dephosphorization;
preparation of graphene additive: dispersing graphene with the particle size of 2-5nm into absolute ethyl alcohol, irradiating for 1-2h under an ultraviolet lamp to obtain a mixed solution, adding Nb powder into the mixed solution, heating for 2h under the condition of microwave 550W, stirring and mixing for 2-4h at 1000rpm to obtain a mixed solution, centrifuging the mixed solution at the rotating speed of 5000rpm for 1h by using a centrifuge to obtain bottom powder, then placing the powder into a vacuum drying furnace, drying for 24h at 100-130 ℃, then flushing hydrogen for 30min at 220 ℃ to obtain powder, and adding a smelting additive into the powder for grinding to obtain a graphene additive;
smelting in a converter: smelting by adopting a top-bottom combined blown converter, and adding molten iron, a metal raw material and a graphene additive into a furnace body for smelting;
LF external refining: fully stirring and dissolving slag in the refining process to prepare yellow and white slag;
continuous casting of the special-shaped blank: adopting immersed flat nozzle full protection casting;
heating the special-shaped blank: heating the special-shaped continuous casting blank in a hot furnace, wherein the heating temperature of the casting blank is 1200-1400 ℃, the heat preservation time is 2-4 hours, and descaling by using high-pressure water after discharging;
rolling and cooling, wherein the cooling adopts water cooling, the cooling speed is controlled to be 10-20 ℃/s, the final cooling temperature is controlled to be below 100 ℃, and straightening is carried out by using a straightener;
and (3) coating powder coating on the surface of the straightened steel, and cutting to a fixed size and bundling after irradiating for 2 hours.
The powder coating comprises polypropylene degradation resin, polyester resin, curing agent, brightening agent, leveling agent, benzoin, titanium pigment and barium sulfate, wherein the mass ratio of the polypropylene degradation resin to the polyester resin is 3:2-27, and the preparation method comprises the steps of adding the polypropylene degradation resin, the polyester resin, the curing agent, the brightening agent, the leveling agent, the benzoin, the titanium pigment, the barium sulfate and pigment into a mixer, mixing at normal temperature, extruding through an extruding machine, tabletting through a tablet press, grinding into powder, and sieving through a 100-200-mesh sieve to obtain the powder coating.
The sulfur process comprises the steps of adding a desulfurizing agent into molten iron, wherein the desulfurizing agent comprises 110 parts by weight of CaO, 13 parts by weight of SiO2, 3 parts by weight of Al and 0.8 part by weight of BaO, stirring at a speed of 20rpm for 30min, heating at a speed of 5 ℃/min, stopping stirring when the temperature is raised to 60 ℃, heating at a speed of 10 ℃/min until the temperature is raised to 120 ℃, keeping the temperature for 20min, and then passing the desulfurized molten iron through a desulfurization filter element to complete desulfurization, wherein the desulfurization filter element comprises 10% of active calcium carbonate, 50% of calcium oxide, 0.5% of magnesium oxide, 20% of calcium carbide, 3% of barium oxide, 5% of powdery sodium silicate, 4.5% of silicon dioxide and 7% of gypsum powder, adding water, molding, and then placing into a puffing box, and introducing hot air at 150-200 ℃ for 2-10 min under 9-12 atmospheric pressure to form porous solids.
The dephosphorization process comprises the steps of adding a dephosphorization agent into molten iron, standing for 30-60min, stirring for 15-20min at the speed of 30rpm, and standing for 30min to complete dephosphorization, wherein the dephosphorization agent comprises ferrous sulfate, magnesium chloride and polyaluminium chloride according to the mass ratio: 1:6:3, a preparation method of the dephosphorizing agent comprises the following steps: taking 50Kg, 300Kg and 150Kg of ferrous sulfate, magnesium chloride and polyaluminium chloride respectively, uniformly stirring the ferrous sulfate, the magnesium chloride and the polyaluminium chloride in an environment with the air humidity of less than 50 percent, and then drying at 45 ℃ for 30 minutes to prepare 500Kg of dephosphorizing agent.
The desilication process comprises the steps of adding a desilication agent into an empty ladle of a hot metal ladle in advance, then filling molten iron into the hot metal ladle, and completing desilication treatment after a blast furnace receives iron and during steelmaking and iron folding, wherein the addition amount of the desilication agent is 40-60kg per ton of molten iron, the desilication agent comprises 30% of blast furnace dust, 30% of fluorite powder and the balance of converter dust, and the desilication agent is prepared by crushing, rolling and grinding required raw materials, so that the proportion of the grain size of the desilication agent is less than 0.074mm and reaches more than 70%; and then uniformly stirring and mixing the mixed material raw material mixing equipment, and drying the mixed powder for later use.
The produced H-steel was tested for yield strength, tensile strength, impact toughness at-40℃and elongation and acid and alkali resistance, as shown in Table 2 below, wherein the acid and alkali resistance was measured for the above-mentioned corrosion-resistant coatings L1 to L8, respectively, according to GB/T9274 "measurement of liquid Medium for color paint and varnish". The soaking method is to soak the corrosion-resistant coatings L1-L8 in acid and alkali solution at room temperature of 30 ℃ for 24 hours respectively, cover the container, clean the corrosion-resistant coatings L1-L8 with water rapidly after the end, and observe the occurrence of the surface of the material. The acid solution and the alkali solution were an aqueous sulfuric acid solution having a concentration of 10 wt% and an aqueous sodium hydroxide solution having a concentration of 10 wt%, respectively.
Comparative example 1:
comparative example 1 was conducted in accordance with the procedure of example 1 except that the chemical composition of the Nb-containing low temperature resistant structural hot rolled H-section steel was different, as shown in table 1 below. The H-shaped steel obtained in comparative example 1 was tested for yield strength, tensile strength, impact toughness at-40℃and elongation and acid and alkali resistance, as shown in Table 2 below.
Comparative example 2:
this comparative example is identical to the chemical composition of form H in example 1, except that no graphene additive is added. The H-shaped steel obtained in comparative example 2 was tested for yield strength, tensile strength, impact toughness at-40℃and elongation and acid and alkali resistance, as shown in Table 2 below.
Table 1: chemical composition (weight ratio) of H-shaped steel of each example
Examples C(%) Si(%) Mn(%) Cr(%) Nb(%) Ti(%) Ce(%) P(%) S(%)
Example 1 0.0750 0.4500 1.5500 0.2300 0.04100 0.1340 0.0009 0.015 0.015
Comparative example 1 0.0750 0.4500 1.5500 0.2300 0.04100 0.1340 0.0000 0.015 0.015
Comparative example 2 0.0750 0.4500 1.5500 0.2300 0.04100 0.1340 0.0009 0.015 0.015
Table 2:
examples Yield strength (MPa) Tensile Strength (MPa) Impact toughness at-40 ℃ (J) Elongation (%) Acid and alkali resistance
Example 1 430 560 173 28 No conditions of light loss, color change, falling, foaming, spots and the like
Comparative example 1 390 503 98 22 No conditions of light loss, color change, falling, foaming, spots and the like
Comparative example 2 415 533 161 25 Shedding off
As can be seen from tables 1 and 2, the hot rolled H-shaped steel produced in example 1 has excellent low temperature resistance toughness and corrosion resistance, meets the mechanical requirements, has a yield strength of not less than 430MPa, a tensile strength of not less than 560MPa, and has an impact toughness of not less than 170J at-40 ℃ and an elongation of not less than 28%. Comparative example 1 lost much of its impact toughness at-40℃after Ce loss, only 98J. Comparative example 2 has substantially reduced corrosion resistance without the addition of a graphene additive.
Finally, it should be noted that: the foregoing description is only illustrative of the preferred embodiments of the present invention, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements or changes may be made without departing from the spirit and principles of the present invention.

Claims (1)

1. A rolling method of hot rolled H-shaped steel for Nb-containing low temperature resistant structure is characterized by comprising the following steps: the method comprises the following steps:
and (3) molten iron pretreatment: including desulfurization, desilication and dephosphorization;
preparation of graphene additive: dispersing graphene with the particle size of 2-5nm into absolute ethyl alcohol, irradiating for 1-2h under an ultraviolet lamp to obtain a first mixed solution, adding Nb powder into the first mixed solution, heating for 2h under the condition of microwave 550W, stirring and mixing for 2-4h at 1000rpm to obtain a second mixed solution, centrifuging the second mixed solution at the rotating speed of 5000rpm by using a centrifuge for 1h to obtain bottom powder, then placing the powder into a vacuum drying furnace, drying for 24h at the temperature of 100-130 ℃, then flushing hydrogen for 30min at the temperature of 220 ℃ to obtain powder, and adding a smelting additive into the powder for grinding to obtain a graphene additive;
smelting in a converter: smelting by adopting a top-bottom combined blown converter, and adding molten iron, a metal raw material and a graphene additive into a furnace body for smelting;
LF external refining: fully stirring and dissolving slag in the refining process to prepare yellow and white slag;
continuous casting of the special-shaped blank: adopting immersed flat nozzle full protection casting;
heating the special-shaped blank: heating the special-shaped continuous casting blank in a hot furnace, wherein the heating temperature of the casting blank is 1200-1400 ℃, the heat preservation time is 2-4 hours, and descaling by using high-pressure water after discharging;
rolling and cooling, wherein the cooling adopts water cooling, the cooling speed is controlled to be 10-20 ℃/s, the final cooling temperature is controlled to be below 100 ℃, and straightening is carried out by using a straightener;
coating powder coating on the surface of the straightened steel, and cutting to length and bundling after irradiating for 2 hours to obtain H-shaped steel;
the H-shaped steel comprises the following chemical components in percentage by weight: 0.0750% of C, 0.4500% of Si, 1.5500% of Mn, 0.2300% of Cr, 0.04100% of Nb, 0.1340% of Ti, 0.0009% of Ce, 0.015% of P, 0.015% of S, and the balance of iron and unavoidable impurities, wherein the mass fraction is 100% in total;
the powder coating comprises polypropylene degradation resin, polyester resin, curing agent, brightening agent, leveling agent, benzoin, titanium pigment and barium sulfate, wherein the mass ratio of the polypropylene degradation resin to the polyester resin is 3:2-27, and the preparation method comprises the steps of adding the polypropylene degradation resin, the polyester resin, the curing agent, the brightening agent, the leveling agent, the benzoin, the titanium pigment, the barium sulfate and pigment into a mixer, mixing at normal temperature, extruding through an extruding machine, tabletting through a tablet press, grinding into powder, and sieving through a 100-200-mesh sieve to obtain the powder coating;
the desulfurizing process includes adding desulfurizing agent comprising CaO 110 weight portions and SiO 110 weight portions into molten iron 2 13 parts of Al 3 parts and 0.8 part of BaO, stirring at 20rpm for 30min while adding, then heating at 5 ℃/min, stopping stirring when heating to 60 ℃, and heating at 10 ℃/min until reaching 120 DEG CHeating, keeping the temperature for 20min, then passing the desulfurized molten iron through a desulfurization filter element to complete desulfurization, wherein the desulfurization filter element comprises 10% of active calcium carbonate, 50% of calcium oxide, 0.5% of magnesium oxide, 20% of calcium carbide, 3% of barium oxide, 5% of powdery sodium silicate, 4.5% of silicon dioxide and 7% of gypsum powder, mixing the above raw materials, adding water, molding, putting the mixture into a puffing box, and introducing hot air at 150-200 ℃ for 2-10 min under 9-12 atmospheric pressure to form porous solid, namely the desulfurization filter element;
the dephosphorization process comprises the steps of adding a dephosphorization agent into molten iron, standing for 30-60min, stirring for 15-20min at the speed of 30rpm, and standing for 30min to complete dephosphorization, wherein the dephosphorization agent comprises ferrous sulfate, magnesium chloride and polyaluminium chloride according to the mass ratio: 1:6:3, a preparation method of the dephosphorizing agent comprises the following steps: taking 50Kg, 300Kg and 150Kg of ferrous sulfate, magnesium chloride and polyaluminium chloride respectively, uniformly stirring the ferrous sulfate, the magnesium chloride and the polyaluminium chloride in an environment with the air humidity of less than 50%, and then drying at 45 ℃ for 30 minutes to prepare 500Kg of dephosphorizing agent;
the desilication process comprises the steps of adding a desilication agent into an empty ladle of a hot metal ladle in advance, then filling molten iron into the hot metal ladle, and completing desilication treatment after a blast furnace receives iron and during steelmaking and iron folding, wherein the addition amount of the desilication agent is 40-60kg per ton of molten iron, the desilication agent comprises 30% of blast furnace dust, 30% of fluorite powder and the balance of converter dust, and the desilication agent is prepared by crushing, rolling and grinding required raw materials, so that the proportion of the grain size of the desilication agent is less than 0.074mm and reaches more than 70%; then uniformly stirring and mixing the mixed material raw material mixing equipment, and drying the mixed powder for later use;
the yield strength of the H-shaped steel=430 MPa, the tensile strength=560 MPa, the impact toughness at-40 ℃ is=170J, the elongation is=28%, and the acid and alkali resistance is free from light loss, discoloration, falling, foaming and spots.
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CN111020359A (en) * 2019-12-30 2020-04-17 广州广钢新材料股份有限公司 Alloy for improving strength of deformed steel bar and manufacturing method thereof
CN112457748A (en) * 2019-09-09 2021-03-09 王宏亮 High-toughness low-temperature-resistant powder coating and preparation method thereof
CN113061813A (en) * 2021-03-22 2021-07-02 吉林省大维科技发展有限公司 Anti-corrosion alloy steel for heating radiator and preparation method thereof
WO2022110455A1 (en) * 2020-11-30 2022-06-02 梁海 Graphene additive and preparation method therefor
CN115505823A (en) * 2022-09-26 2022-12-23 包头钢铁（集团）有限责任公司 Smelting continuous casting method of hot-rolled H-shaped steel for Nb-containing low-temperature-resistant structure

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