CN117127105A - Low-yield-ratio heavy-duty industrial atmospheric corrosion-resistant bridge steel plate and production method thereof - Google Patents

Low-yield-ratio heavy-duty industrial atmospheric corrosion-resistant bridge steel plate and production method thereof Download PDF

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CN117127105A
CN117127105A CN202311102203.7A CN202311102203A CN117127105A CN 117127105 A CN117127105 A CN 117127105A CN 202311102203 A CN202311102203 A CN 202311102203A CN 117127105 A CN117127105 A CN 117127105A
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percent
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steel plate
atmospheric corrosion
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林田子
杨颖�
张哲�
王玉博
纪汶伯
张涛
李琳
陈义庆
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Angang Steel Co Ltd
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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
    • 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
    • B22D11/16—Controlling or regulating processes or operations
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    • B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
    • B22D11/182—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level by measuring temperature
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    • 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
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    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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Abstract

The application provides a low yield ratio heavy industry atmospheric corrosion resistant bridge steel plate and a manufacturing method thereof, wherein the steel plate comprises the following components in percentage by weight: c:0.07 to 0.10 percent of Si:0.10 to 0.30 percent of Mn:0.60 to 1.00 percent, less than or equal to 0.010 percent of P, less than or equal to 0.003 percent of S and less than or equal to Nb:0.02% -0.04%, ni:0.15% -0.35%, cu:0.10% -0.40%, mo:0.20 to 0.50 percent of Cr:1.50 to 2.40 percent of Ti:0.01% -0.030%, sb:0.03 to 0.10 percent of Al:0.015 to 0.040 percent, and the balance of iron and unavoidable impurities. The production method of the steel plate comprises molten iron pretreatment, smelting, continuous casting, slab heating, rolling and straightening. The steel plate provided by the application has the advantages that the yield strength is more than or equal to 345MPa, the tensile strength is more than or equal to 510MPa, the elongation after fracture is more than or equal to 30%, the yield ratio is less than or equal to 0.75, the reduction of area in the thickness direction is more than or equal to 70%, and the low-temperature impact energy at minus 40 ℃ is more than or equal to 300J. The annual corrosion rate is less than or equal to 0.05mm/a in the simulated heavy industry atmosphere environment, and the corrosion performance is improved by 4-8 times compared with that of the common Q345 qE.

Description

Low-yield-ratio heavy-duty industrial atmospheric corrosion-resistant bridge steel plate and production method thereof
Technical Field
The application belongs to the field of metal materials, and particularly relates to a low yield ratio heavy industry atmospheric corrosion resistant bridge steel plate and a production method thereof.
Background
The material corrosion widely exists in various fields of social and economic construction, various accidents caused by corrosion are striking eyes and frightening, and serious influence is caused on the development of social and economic development. The research shows that the Chinese corrosion cost is about 3.4% of GDP. The metallic materials are often exposed to the atmosphere and it has been shown that about 80% of the metallic components are used in the atmosphere, with the metal lost by atmospheric corrosion accounting for more than about half of the total corrosion loss of the metal, with significant direct and indirect economic losses, especially with the most significant corrosion of carbon steel by industrial atmospheres.
Because of the vast territories of China, the large climate zones of the temperate zone, subtropical zone and tropical zone 3 are spanned, and the difference of the natural environment of the atmosphere is large, the influence factors are complex. In addition, with the development of the industry in China,the atmospheric environment is increasingly polluted, and most of the atmospheric environment in inland cities contains SO 2 And NO x And the industrial emission of pollution components and the interaction of all environmental factors influencing the corrosion of weather-resistant bridge steel lead the corrosion development mechanism and the change rule to have larger difference. In some traditional industries, such as enterprises of coal mines, steel, petroleum and petrochemical industry, asphalt smoke, hydrogen fluoride, dust, NOx, SO are generated 2 、CO、H 2 S、Cl 2 Etc. are major air pollutants, where SO 2 Suspended particles, fluoride, cl 2 The equivalent content of SO exceeds the national corresponding standard 2 The content is higher. The corrosive effects of such heavy industrial atmospheric environments on commonly used carbon steels are more complex and severe.
Along with the vigorous development of transportation industry, the requirements on the load capacity, the earthquake resistance, the corrosion resistance and the like of the bridge structure are continuously improved, so that the bridge structure needs to consider not only the basic mechanical properties of materials, but also the welding and corrosion resistance of the materials, and particularly ensures the safety of the life cycle of the bridge in the heavy industrial atmospheric environment.
At present, the existing bridge steel can meet most of the market demands in the bridge field, but the weather-resistant bridge steel, especially the corrosion problem of the bridge steel in the heavy industry complex atmospheric environment, is to be researched, and partial patents and documents are found through search, but the recorded contents are obviously different from the components, the production method, the performance, the product category and the like in the technical scheme of the application.
Chinese patent application No. CN 109797342A discloses a high strength, high toughness, atmospheric corrosion resistant steel sheet for steel structure fabrication and a method for manufacturing the same, the elemental composition wt%: c:0.03 to 0.10 percent, si:0.30 to 0.50 percent, mn:1.10 to 1.50 percent, P is less than 0.010 percent, S is less than 0.003 percent, cr: 0.45-0.70%, cu:0.25 to 0.40 percent, ni:0.30 to 0.40 percent, alt: 0.030% or more, ti:0.006 to 0.030 percent, V: 0.040-0.080%, mo: 0.02-0.08%, ca:0.0010 to 0.0030 percent, N:0.0020 to 0.0080 percent, B:0.0002 to 0.0030 percent, ce: 0.001-0.010%, atmospheric corrosion resistance index I >6.5, CEV <0.54, pcm <0.27, and the balance of Fe and unavoidable impurities. The application adopts specific chemical composition design and a steel plate modulation process to obtain the high-performance steel plate with the bainite structure, and can be used for manufacturing steel structures such as bridges, high-rise buildings and the like. However, the application has the defects that the steel plate has no lower yield ratio and poor safety performance, rare elements such as Ca, B, ce and the like are added, smelting is difficult, and the production cost is increased; the carbon equivalent is too high and the welding performance is poor. And quenching and tempering are needed, and the process is complex.
The application discloses a TMCP yield 420MPa bridge steel plate and a production method thereof, wherein the chemical components and the mass percentage of the steel plate are as follows: 0.07 to 0.09 percent of C, 0.25 to 0.50 percent of Si, 1.40 to 1.60 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 0.15 to 0.25 percent of Ni, 0.10 to 0.20 percent of Cr, 0.020 to 0.030 percent of Nb, 0.030 to 0.050 percent of Al, 0.030 to 0.040 percent of V, and the balance of Fe and unavoidable impurities; the production method comprises the working procedures of smelting, continuous casting, heating, rolling and cooling. The chemical components of the steel plate adopt low C, nb and V microalloying design, and the alloy elements such as Ni, cr and the like are used for assisting to ensure the strength and toughness of the steel plate to be matched, so that a composite structure of bainite and ferrite is obtained, and the maximum thickness of the steel plate can reach 70mm. However, the disadvantage of the patent application of the application is that it does not have the ability to withstand industrial atmospheric corrosion.
The application of China patent application No. CN 106011658A discloses a marine climate resistant corrosion resistant steel and a production method thereof, wherein the chemical components (according to weight percentage) are as follows: c: less than or equal to 0.06 percent, si: less than or equal to 0.50 percent, less than or equal to 1.50 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.005 percent of S, and less than or equal to Ni:3.0 to 4.5 percent, cu:0.8 to 2.0 percent of Al:0.5 to 1.0 percent, and the balance of iron and unavoidable impurities. The manufacturing method comprises the steps of conventional converter smelting and the like, continuous casting into a blank, heating, hot rolling and coiling the continuous casting blank, and cooling to room temperature by adopting a front-stage cooling mode. The corrosion resistance of the steel plate in high-temperature, high-humidity and high-salinity marine climate is improved. The application of the patent document is limited to producing thin steel plates by adopting a hot continuous rolling mode, and the steel plates produced by adopting the hot continuous rolling mode have large internal stress, are not suitable for further manufacturing bridge members with complex shapes and the like, and are not provided with low-temperature toughness, so that the steel is not suitable for being used as a public iron bridge.
The application relates to industrial atmospheric corrosion resistant high-strength bolt steel for a coating-free bridge structure and a manufacturing method thereof, belonging to the technical field of high-strength bolt steel for bridge structures. The weight percentages of the components are as follows: 0.16 to 0.45 percent of C, 0.01 to 2.2 percent of Si, 0.3 to 2.2 percent of Mn, 0.001 to 0.024 percent of P, 0.002 to 0.025 percent of S, 0.0005 to 0.0100 percent of B, 0.04 to 0.50 percent of Ti, 0.01 to 0.20 percent of V, 0.001 to 0.10 percent of Al, 0.001 to 0.34 percent of Cr, 0.2 to 0.5 percent of Cu, 0.2 to 1.5 percent of Ni, and the balance of Fe and trace impurities. The method is suitable for producing bolts with the specification range of M16-30mm, and after bolts are manufactured by a bolt processing factory, the hardening and tempering heat treatment process system is 840-920 ℃ oil quenching and 380-625 ℃ tempering, so that the optimal toughness matching is obtained. The coating-free bridge structural plate and profile matching connection method has the advantages that the coating-free bridge structural plate and profile matching connection method is used, and the coating-free bridge structural plate and profile matching connection method has excellent industrial atmospheric corrosion resistance and low temperature resistance. The application of the patent document is limited to the production of bridge bolts, has more alloy elements such as C, ni, B and the like, has complex process, does not have low yield ratio and excellent ductility and toughness, and is not suitable for bridge steel.
Disclosure of Invention
Aiming at the defects of the prior art, the application aims to provide a low yield ratio heavy industry atmospheric corrosion resistant bridge steel plate and a production method thereof. The product produced according to the chemical components and the production process of the steel has high toughness, low yield ratio, high plasticity and excellent heavy industry atmospheric corrosion resistance and welding performance, the whole plate performance is uniform, the production efficiency can be further improved by adopting hot rolling, the construction efficiency and the whole safety of bridge structural engineering are improved, the weathering steel does not need to be coated or coated less, the resource saving and environmental protection functions are realized, and the product is a low-carbon product.
According to the low yield ratio heavy-duty industrial atmospheric corrosion resistant bridge steel plate and the production method thereof, the welding performance and toughness of the material are improved through low C and low Mn in component design, nb and Ti elements are utilized to inhibit the growth of austenite grains and promote nucleation in the austenite transformation process to refine the grains, the thickness core structure of the steel plate is controlled, and the structure uniformity is improved; the effect of Nb for inhibiting austenite recrystallization is utilized, the rolling temperature is increased, grain refinement is promoted, and the corrosion performance is improved; meanwhile, elements such as Cr, ni, cu and the like are utilized to improve the weather resistance of the steel plate, and the quenching degree of the steel plate can be further improved by the matched addition of Cr and Mo, so that the cooling rate is improved in the air cooling process, grains are refined, and the strength improvement and the uniformity of the structure in the thickness direction are achieved. The micro-structure with high thickness, low yield ratio, excellent atmospheric corrosion resistance, excellent weldability and other comprehensive performances is obtained by matching with corresponding smelting, heating, rolling and other production processes.
The application aims at realizing the following steps:
the low yield ratio heavy industrial atmospheric corrosion resistant bridge steel plate comprises the following components in percentage by weight: c:0.07 to 0.10 percent of Si:0.10 to 0.30 percent of Mn:0.60 to 1.00 percent, less than or equal to 0.010 percent of P, less than or equal to 0.003 percent of S and less than or equal to Nb:0.02% -0.04%, ni:0.15% -0.35%, cu:0.10% -0.40%, mo:0.20 to 0.50 percent of Cr:1.50 to 2.40 percent of Ti:0.01% -0.030%, sb:0.03 to 0.10 percent of Al:0.015 to 0.040 percent, and the balance of iron and unavoidable impurities.
Further, the steel sheet Cr/mo=3 to 7.
Further, the steel plate has an atmospheric corrosion resistance index I value of 6.20 or more, i=26.01 (% Cu) +3.88 (% Ni) +1.20 (% Cr) +1.49 (% Si) +17.28 (% P) -7.29 (% Cu) (% Ni) (% P) -33.39 (% Cu) 2 。
Further, the microstructure of the steel plate is mainly ferrite and pearlite, the ferrite volume percentage accounts for 60-85%, the ferrite grain size is more than or equal to 9 grades, and the average size of ferrite grains is less than 20 mu m.
Further, the thickness of the steel plate is 6-100 mm.
Further, the yield strength of the steel plate is more than or equal to 345MPa, the tensile strength is more than or equal to 510MPa, the elongation after fracture is more than or equal to 30%, the yield ratio is less than or equal to 0.75, the reduction of area in the thickness direction is more than or equal to 70%, and the low-temperature impact energy at minus 40 ℃ is more than or equal to 300J.
The reason for designing the components of the application is as follows:
C：0.07％～0.10％
the C has great influence on the strength, toughness and welding performance of the steel, and has influence on the corrosion resistance of the steel grade; the carbon content is low, and the toughness, the welding performance and the corrosion resistance are improved; however, the strength is low when the carbon content is lower than 0.070%, and the smelting and welding difficulties are high; if the carbon content is higher than 0.10%, more pearlite structures are generated, the performance of the atmospheric corrosion resistant bridge steel is not good, and the strength, the elongation and the toughness are reduced; therefore, the application limits the content of C to 0.07% -0.10%.
Si：0.10％～0.30％
Si is an essential element for steelmaking deoxidization, can also play a solid solution strengthening role, improves the strength of steel, and can also improve the corrosion resistance of the steel, but too high content of Si can reduce the toughness of the steel and is also unfavorable for welding performance. Therefore, si is limited to 0.10% to 0.30% in the steel grade of the present application.
Mn：0.60％～1.00％
Mn can form a substitutional solid solution in steel, plays a strong solid solution strengthening role, and enables yield strength and tensile strength to be linearly increased, and the element content hardly reduces plasticity and toughness of the steel while increasing the strength of the steel in a certain range; however, too high a manganese content can increase the carbon equivalent of the steel and can reduce the heavy industrial atmospheric corrosion resistance of the steel. Therefore, the suitable interval for adding Mn according to the strength requirement in the steel grade of the present application is 0.60% to 1.00%.
P≤0.010％
P is one of the alloy elements which is most effective in improving the corrosion resistance of the steel plate, and when the P and Cu are added into the steel in a combined way, a barrier layer which takes Cu and P as main components can be formed between a substrate and a rust layer, so that a better composite effect is shown; however, P deteriorates the weldability of steel, worsens the plasticity, toughness of steel, and particularly drastically reduces low-temperature impact toughness; local segregation is also liable to occur, forming a band-like structure. Therefore, in the present application, the P content is controlled to P.ltoreq.0.010%.
S≤0.003％
S is the element which is the most harmful to corrosion resistance of steel, reduces sulfur content, resists industrial atmospheric corrosion of steel and resists H 2 Corrosion performance of S and the likeAll have good functions; meanwhile, the high sulfur content also has adverse effects on toughness, plasticity and the like of the steel. The steel grade control S is less than or equal to 0.003 percent.
Nb：0.02％～0.04％
Nb is an important additive element of the application, and Nb is generated in salt solution 2 O 5 Is a very stable oxide, can be attached on a steel matrix, and has the functions of isolating the contact between the corrosive medium and oxygen and the steel matrix and inhibiting corrosion. The method can effectively delay the recrystallization of deformed austenite, prevent the austenite grain from growing greatly, improve the austenite recrystallization temperature, refine the grains and improve the strength and toughness of the steel; nb is a strong carbon and nitride forming element, and can combine with carbon and nitrogen to form a stable and fine carbon and nitride precipitate phase, and the dispersed precipitate phase can make corrosion uniform. Therefore, the Nb content is limited to 0.02% to 0.04% in the present application.
Ti：0.01％～0.03％
The addition of Ti can refine austenite grains of a steel billet during reheating and welding a heat affected zone, and plays a role in improving the plasticity and toughness of the steel plate; and Ti can form tiny carbide or nitride with C and N, prevent the growth of crystal grains in the heating, rolling and welding processes of the billet, and improve the toughness of a base metal and a welding heat affected zone. Therefore, in the present application, the Ti content is limited to 0.01% to 0.03% in combination with the N content in the steel.
Cr：1.5％～2.4％
Cr is used for improving the heavy industry atmospheric corrosion resistance, and Cr enrichment in the rust layer can accelerate unstable gamma-FeOOH to be converted into alpha-FeOOH with higher stability, so that crystal grains of the rust layer are thinned, the enriched Cr can fill cracks and holes in the rust layer, the compactness and stability of the rust layer are improved, the structure of the rust layer is changed by adding Cr, a compact oxide layer is generated together with Cu, and the ingress of oxygen is prevented. Cu and Cr are simultaneously dissolved in the matrix and are combined with oxygen to separate out at the defect (crack and hole) of the rust layer along with the corrosion, so that corrosive medium is prevented from entering the matrix, and the corrosion of metal is slowed down. Cu and Sb element are mutually matched and mutually cooperated, an alpha-FeOOH and delta-FeOOH compact rust film layer is generated on the surface of the steel plate, the steel is protected from being corroded continuously, when Cr is lower than 1.5%, the heavy industry atmosphere corrosion resistance effect is poor, when Cr is higher than 2.4%, the steel-making difficulty is high, the hot workability of the steel plate is deteriorated, and the cost is too high, so that the Cr content is limited to be 1.5% -2.4%.
Cu：0.10％～0.40％
The Cu element can effectively improve the corrosion resistance of the steel under the heavy industry atmosphere, promote the anode passivation of a steel matrix, inhibit rust crystallization, retard the growth of rust crystals, refine the grains of an inner rust layer and repair cracks and holes in the rust layer, thereby generating a rust layer with stronger protection. Cu enrichment can prevent crystallization of rust layer, inhibit entry of O, reduce conductivity of rust layer and prevent corrosion by surface deposition. However, when the Cu content is high, the surface property of the steel plate is deteriorated; in addition, the strength and hot workability of the steel plate are facilitated under a certain Cu content, the hot rolling edge cracking tendency of the steel plate is effectively reduced, and the surface quality of the steel plate is remarkably improved. Cu also has the effect of reducing work hardening, improves the plasticity of the steel plate, and greatly improves the low-temperature toughness. Therefore, the Cu content is limited to 0.10% to 0.40% in the steel grade of the present application.
Sb：0.03％～0.10％
The addition of Sb can promote the surface of the steel plate matrix to form a layer of uniform and compact oxide film (rich in Sb, cu, cr and other elements), and Cu in the oxide film 2+ The delta-FeOOH is promoted to be increased, the delta-FeOOH can effectively prevent moisture, oxygen, sulfide and the like in heavy industrial atmosphere from continuously entering a matrix to form a corrosion internal environment, and the Sb can enable the alpha-FeOOH and the delta-FeOOH to generate a synergistic effect so as to jointly improve the corrosion resistance of the engine body. The Sb content is too low, so that the passivation film is unevenly dispersed, and the integral anti-corrosion effect is not achieved; when the design upper limit is exceeded, the anti-corrosion effect is achieved, but the hot workability is significantly reduced. Therefore, the Sb content is limited to 0.03% to 0.10%.
Mo：0.20％～0.50％
The Mo element has outstanding effect on improving the heavy industrial atmospheric performance of the weathering steel, the Mo element in the rust layer is easy to be converted into molybdate, and along with the corrosion, the molybdate reacts with iron ions to generate FeMoO 4 And is deposited on the active site of the anode to inhibit the dissolution of the anode and greatly slow down the corrosion. Particularly in the environment containing sulfide, the resistance to pitting corrosion and crevice corrosion can be remarkably improved, and Mo contributes to the refinement of austenite grains during rolling, but when the content exceeds 0.5%, the weldability is reduced; in addition, mo is a noble element, resulting in a significant increase in the cost of steel. Therefore, the Mo content in the present steel grade is limited to 0.20% to 0.50%.
Ni：0.15％～0.35％
The addition of Ni can make the self-corrosion potential of metal move forward, and can refine the crystal grains of the inner rust layer, so that the compactness of the inner rust layer is increased, and the purpose of slowing down corrosion is achieved. Ni can effectively improve the low-temperature toughness of steel and also can improve the hot brittleness caused by copper in the steel, and the Ni element has no adverse effect on the hardening property and toughness of a welding heat affected zone of the steel; however, ni is a valuable element, and the content is not too high. Therefore, the Ni content is limited to 0.15% to 0.35% in the steel grade of the present application.
Al：0.015％～0.040％
Al is a commonly used deoxidizer in steel, a small amount of Al is added into the steel, so that grains can be refined, the impact toughness is improved, the Al also has oxidation resistance and corrosion resistance, the combination of Al, cr and Si can obviously improve the high-temperature non-skinning performance of the steel, the surface quality of the steel plate is improved, and oxide inclusions are easily formed due to overhigh Al, so that the content of the Al is limited to be 0.015-0.040%.
The second technical scheme of the application is to provide a manufacturing method of the low yield ratio heavy industry atmospheric corrosion resistant bridge steel plate, which comprises the steps of molten iron pretreatment, smelting, continuous casting, slab heating, rolling and straightening.
Wherein the casting superheat degree of the continuous casting billet is 10-25 ℃, and the thickness of the continuous casting billet/the thickness of the finished steel plate is as follows: 3 to 50 percent; the casting superheat degree and the continuous casting billet pulling speed can be controlled, so that the quality defect of a casting billet can be effectively reduced; the grain size can be effectively controlled by increasing the compression ratio of the continuous casting blank to the finished steel plate.
The temperature of the continuous casting billet heating section is 1200-1250 ℃, the temperature of the soaking section is 1190-1230 ℃, and the time of the soaking section is not less than 90min; the heating temperature can meet the solid solution of alloy, especially Nb, cr and Ni elements, and simultaneously prevent austenite grains from excessively growing; the heating time can ensure the temperature uniformity of the blank.
The initial rolling temperature of rough rolling is 1070-1095 ℃, the final rolling temperature of rough rolling is 1010-1045 ℃, the rolling temperature and the deformation process of the rough rolling stage enable austenite grains to be recrystallized and inhibit the growth of the grains, the rough rolling stage ensures that the deformation rate of each pass of at least the last 2 passes is more than 15 percent, the pass interval is not more than 15 seconds, and the accumulated reduction rate is more than or equal to 50 percent; the rough rolling end section adopts a large reduction and short interval process, so that the equipment load of the building steel can be reduced, the austenite is promoted to be recrystallized by utilizing the multi-pass large reduction deformation superposition effect, the grain refinement target is achieved, and the method is suitable for producing the heavy industry atmospheric corrosion resistant bridge steel plate.
The thickness of the intermediate blank to be warmed is 1.25 to 3.5t, wherein t is the thickness of a finished steel plate, the finish rolling start temperature is 820 to 849 ℃, the finish rolling temperature is 750 to 779 ℃, and the single-pass deformation rate is not lower than 10 percent; the proper thickness of the intermediate blank to be warmed can not only meet the accumulation of austenite deformation and deformation energy in an unrecrystallized area, but also ensure that enough deformation rate is obtained in a rough rolling stage under the condition of a certain thickness of an original casting blank so as to achieve the aim of grain refinement; the accumulation of austenite deformation energy and the induction precipitation of fine precipitation phases of Nb and Ti are promoted by the low finish rolling temperature, and the nucleation position is increased; the enough deformation at the phase transition point temperature at the final stage of finish rolling is favorable for the generation of fine ferrite, the effective grain size can be reduced, the low-temperature toughness is obviously improved, and the thickness of the rolled steel plate is 6-100 mm.
And (5) carrying out hot straightening and air cooling on the rolled steel plate. In order to obtain the best effect, the steel plates are subjected to stacking heat preservation treatment after rolling, and the stacking temperature is 300-450 ℃. In the stacking self-tempering process, the strength of the steel is adjusted, and meanwhile, the toughness and the plasticity of the steel are improved, so that the aim of homogenizing the performance is fulfilled.
The final microstructure of the steel plate is mainly a fine ferrite and pearlite structure, wherein the volume percent of ferrite is 60-85%, the ferrite grain size is more than or equal to 9 levels, and the average size of polygonal ferrite grains is less than 20 mu m; the steel plate has low yield ratio, high elongation, good welding performance and low-temperature toughness, and can be used for bridge engineering under the condition of heavy industry atmosphere.
The application has the beneficial effects that:
1. the application is based on low C and low Si, mainly utilizes Nb and Ti elements to inhibit austenite grain growth and promote nucleation in the austenite transformation process to refine grains, produces the heavy-duty industrial atmospheric corrosion resistant bridge steel with excellent comprehensive performance through the corresponding unique production process by proportioning of the alloy elements of the heavy-duty industrial atmospheric corrosion resistant alloy such as Cr, mo, cu, ni, sb, wherein the microstructure of the steel plate is ferrite and pearlite, the ferrite volume percentage is 60-85%, the ferrite grain size is more than or equal to 9 grade, and the average size of polygonal ferrite grain is less than 20 mu m.
2. The low yield ratio heavy industry atmospheric corrosion resistant bridge steel plate has the advantages that the yield strength is more than or equal to 345MPa, the tensile strength is more than or equal to 510MPa, the elongation after fracture is more than or equal to 30%, the yield ratio is less than or equal to 0.75, the reduction of area in the thickness direction is more than or equal to 70%, the low temperature impact energy at-40 ℃ is more than or equal to 300J, the steel plate has low yield ratio, high elongation, good welding performance and low temperature toughness, and the bridge engineering application under the heavy industry atmospheric condition is met.
3. The low yield ratio heavy industry atmospheric corrosion resistant bridge steel plate provided by the application has the advantages that the annual corrosion rate is less than or equal to 0.05mm/a in the simulated heavy industry atmospheric environment, the corrosion performance is improved by 4-8 times compared with that of the common Q345qE, the low yield ratio heavy industry atmospheric corrosion resistant bridge steel plate can be widely applied to engineering structures such as bridges, pipe galleries and the like in the heavy industry atmospheric environment, and meanwhile, the low yield ratio heavy industry atmospheric corrosion resistant bridge steel plate can also replace repeated coating of galvanization or paint, is beneficial to environmental protection, belongs to green manufacturing, and fills the blank in the field.
Drawings
FIG. 1 is a microstructure gold phase diagram (ferrite+pearlite) of example 1 of the present application.
Detailed Description
The application is further illustrated by the following examples.
According to the component proportion of the technical scheme, the embodiment of the application carries out molten iron pretreatment, smelting, continuous casting, slab heating, rolling and straightening.
Slab heating
The temperature of the continuous casting billet heating section is 1200-1250 ℃, the temperature of the soaking section is 1190-1230 ℃, and the time of the soaking section is not less than 90min;
rolling
The initial rolling temperature of rough rolling is 1070-1095 ℃, the final rolling temperature of rough rolling is 1010-1045 ℃, the deformation rate of each pass of at least the last 2 passes is ensured to be more than 15% in the rough rolling stage, the pass interval is not more than 15s, and the accumulated reduction rate is more than or equal to 50%; the thickness of the intermediate blank to be warmed is 1.25 to 3.5t, wherein t is the thickness of a finished steel plate, the initial rolling temperature of finish rolling is 820 to 849 ℃, the final rolling temperature of finish rolling is 750 to 779 ℃, the single-pass deformation rate is not less than 10 percent, and the rolled steel plate is subjected to hot straightening and air cooling.
Further, the casting superheat degree of the continuous casting blank in the continuous casting process is 10-25 ℃, and the thickness of the continuous casting blank/the thickness of a finished steel plate is as follows: 3 to 50.
Further, the steel plates are subjected to stacking heat preservation treatment after the rolling process, and the stacking temperature is 300-450 ℃.
The chemical compositions of the examples of the application are shown in Table 1; the smelting continuous casting and slab heating processes of the corresponding examples are shown in Table 2; the rough rolling process of the corresponding example is shown in table 3; the finish rolling process of the corresponding example is shown in Table 4; the properties and microstructure proportions of the corresponding examples are shown in Table 5; the main components and the contents of the heavy industry atmospheric corrosion resistant solution are shown in Table 6; examples the dry and wet alternate corrosion rates at the heavy industrial atmosphere are shown in table 7.
TABLE 1 chemical composition wt% of the examples of the application
TABLE 2 continuous casting and casting blank heating process according to an embodiment of the present application
TABLE 3 roughing process of the examples of the application
TABLE 4 finish rolling process according to the embodiment of the application
TABLE 5 Properties and microstructure proportions of the inventive examples
The heavy duty industrial atmospheric corrosion resistant steel of the above example and the comparative example Q345qE steel were processed into corrosion test pieces, and dry-wet alternation accelerated corrosion test under the heavy duty industrial atmospheric environment was performed by a dip-in-week method, and physicochemical properties of the corrosion solution are shown in table 6. The test materials were etched in the medium for 360 hours and then removed for data processing, and the results of the etching test are shown in table 7.
TABLE 6 major Components and content of heavy Industrial atmospheric Corrosion resistant solution
Media name Content (mol/L)
NaHSO 3 0.01
NaHCO 3 0.01
NaNO 3 0.01
(NH4) 2 SO 4 0.002
NaCl 0.001
NaF 0.001
Table 7 examples alternate wet and dry corrosion rates in heavy industrial atmospheres (360 h)
As can be seen from the above, the steel plate has the yield strength of more than or equal to 345MPa, the tensile strength of more than or equal to 510MPa, the elongation after fracture of more than or equal to 30%, the yield ratio of less than or equal to 0.75, the reduction of area in the thickness direction of more than or equal to 70%, the low-temperature impact energy of minus 40 ℃ of more than or equal to 300J, and the steel plate has low yield ratio, high elongation, good welding performance and low-temperature toughness, and can be used for bridge engineering under the condition of heavy industry atmosphere. The annual corrosion rate is less than or equal to 0.05mm/a in the simulated heavy industrial atmosphere environment, the corrosion performance is improved by 4-8 times compared with that of the common Q345qE, and the method can be widely applied to engineering structures such as bridges, pipe galleries and the like in the heavy industrial atmosphere environment, can also replace repeated coating of galvanization or paint, is beneficial to environmental protection, belongs to green manufacturing, and fills the blank in the field.
The present application has been properly and fully described in the foregoing embodiments by way of example only, and not by way of limitation, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the application, any modification, equivalent substitution, improvement, etc. should be included in the scope of the application, and the scope of the application is defined by the claims.

Claims (9)

1. The low yield ratio heavy industrial atmospheric corrosion resistant bridge steel plate is characterized by comprising the following components in percentage by weight: c:0.07 to 0.10 percent of Si:0.10 to 0.30 percent of Mn:0.60 to 1.00 percent, less than or equal to 0.010 percent of P, less than or equal to 0.003 percent of S and less than or equal to Nb:0.02% -0.04%, ni:0.15% -0.35%, cu:0.10% -0.40%, mo:0.20 to 0.50 percent of Cr:1.50 to 2.40 percent of Ti:0.01% -0.030%, sb:0.03 to 0.10 percent of Al:0.015 to 0.040 percent, and the balance of Fe and unavoidable impurities.
2. The low yield ratio heavy industrial atmospheric corrosion resistant bridge steel sheet according to claim 1, wherein the bridge steel sheet Cr/mo=3 to 7.
3. The low yield ratio heavy industrial atmospheric corrosion resistant bridge steel sheet according to claim 1, wherein the steel sheet has an atmospheric corrosion resistance index I value of 6.20 or more, i=26.01 (%cu) +3.88 (%ni) +1.20 (%cr) +1.49 (%si) +17.28 (%p) -7.29 (%cu) (%ni) -9.10 (%ni) (%p) -33.39 (%cu) 2 。
4. The low yield ratio heavy industrial atmospheric corrosion resistant bridge steel sheet according to claim 1, wherein the steel sheet microstructure is ferrite + pearlite structure, the ferrite volume percentage is 60% -85%, the ferrite grain size is greater than or equal to 9 grades, and the average ferrite grain size is less than 20 μm.
5. The low yield ratio heavy industrial atmospheric corrosion resistant bridge steel sheet according to claim 1, wherein the steel sheet has a thickness of 6 to 100mm.
6. The low yield ratio heavy industrial atmospheric corrosion resistant bridge steel plate according to claim 1, wherein the steel plate has a yield strength of not less than 345MPa, a tensile strength of not less than 510MPa, an elongation after fracture of not less than 30%, a yield ratio of not more than 0.75, a reduction of area in the thickness direction of not less than 70%, and a low-temperature impact energy of not less than 300J at-40 ℃.
7. A method for producing a low yield ratio heavy industrial atmospheric corrosion resistant bridge steel sheet according to any one of claims 1 to 6, comprising pretreatment of molten iron, smelting, continuous casting, slab heating, rolling, straightening, characterized in that,
slab heating
The temperature of the continuous casting billet heating section is 1200-1250 ℃, the temperature of the soaking section is 1190-1230 ℃, and the time of the soaking section is not less than 90min;
rolling
The initial rolling temperature of rough rolling is 1070-1095 ℃, the final rolling temperature of rough rolling is 1010-1045 ℃, the deformation rate of each pass of at least the last 2 passes is ensured to be more than 15% in the rough rolling stage, the pass interval is not more than 15s, and the accumulated reduction rate is more than or equal to 50%; the thickness of the intermediate blank to be warmed is 1.25-3.5 t, t is the thickness of a finished steel plate, the initial rolling temperature of finish rolling is 820-849 ℃, the final rolling temperature of finish rolling is 750-779 ℃, the single-pass deformation rate is not less than 10%, and the rolled steel plate is subjected to hot straightening and air cooling.
8. The method for manufacturing a low yield ratio heavy industry atmospheric corrosion resistant bridge steel sheet according to claim 7, wherein the superheat degree of casting of the continuous casting is 10-25 ℃, and the thickness of the continuous casting/the thickness of the finished steel sheet is=3-50.
9. The method for manufacturing the low yield ratio heavy industrial atmospheric corrosion resistant bridge steel plate according to claim 7, wherein the steel plate is subjected to stacking heat preservation treatment after the rolling process, and the stacking temperature is 300-450 ℃.
CN202311102203.7A 2023-08-28 2023-08-28 Low-yield-ratio heavy-duty industrial atmospheric corrosion-resistant bridge steel plate and production method thereof Pending CN117127105A (en)

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