CN111235472B - 420 MPa-grade low-alloy corrosion-resistant steel and preparation method and application thereof - Google Patents

420 MPa-grade low-alloy corrosion-resistant steel and preparation method and application thereof Download PDF

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CN111235472B
CN111235472B CN201911299435.XA CN201911299435A CN111235472B CN 111235472 B CN111235472 B CN 111235472B CN 201911299435 A CN201911299435 A CN 201911299435A CN 111235472 B CN111235472 B CN 111235472B
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resistant steel
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CN111235472A (en
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姜杉
侯园虹
杨建炜
曹建平
蔡宁
侯强
王胜荣
狄国标
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Shougang Corp
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • 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
    • C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
    • 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
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • 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
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • 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
    • C21D2211/002—Bainite
    • 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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  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

The invention relates to 420 MPa-level low-alloy corrosion-resistant steel and a preparation method and application thereof, belonging to the technical field of steel materials and metallurgy, wherein the 420 MPa-level low-alloy corrosion-resistant steel comprises the following chemical components in percentage by weight: c: 0.03-0.10%, Si: 0.01-1.0%, Mn: 1.0-2.1%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Als is less than or equal to 0.02%, Cu: 0.1-0.6%, Ni: 0.2-4.0%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01% of Fe and inevitable impurities as the balance, wherein the contents of Ca, Mg and O in percentage by weight meet the following conditions: (Ca + Mg)/O is more than or equal to 1.0; compared with the similar low-alloy corrosion-resistant steel, the 420 MPa-grade low-alloy corrosion-resistant steel provided by the embodiment of the invention has the advantage that the corrosion resistance is improved by 50%.

Description

420 MPa-grade low-alloy corrosion-resistant steel and preparation method and application thereof
Technical Field
The invention belongs to the technical field of steel materials and metallurgy, and particularly relates to 420 MPa-grade low-alloy corrosion-resistant steel and a preparation method and application thereof.
Background
The low alloy corrosion resistant steel is low alloy steel which is added with proper amount of one or more alloy elements on the basis of carbon steel in order to improve the corrosion resistance of the steel. For a long time, the low-alloy structural steel in China is always developed in the main directions of multiple varieties, high strength and toughness, complex load, easiness in welding and the like in the aspects of design and manufacture, and the research on corrosion-resistant steel is relatively late. Current corrosion resistant low alloyThe steel is mainly suitable for continental climate environments, and the component steel is very seriously corroded in tropical and subtropical environments such as south sea and the like, high-temperature, high-humidity and high-salt environments, and can not meet the requirement of service performance. The traditional weathering steel is mostly based on a component system of Cor-Ten steel, but the component system is generally suitable for rural areas and industrial atmospheric environment and has high Cl content-The environment of deposition rate, such as coastal atmosphere environment or south sea island environment, has a problem of insufficient corrosion resistance.
Patent CN106011658A introduces a marine climate corrosion resistant steel, the alloy composition of which is designed to be C less than or equal to 0.06%, Si less than or equal to 0.5%, Mn less than or equal to 1.5%, P less than or equal to 0.010%, S less than or equal to 0.005%, Ni: 3.0% -4.5%, Cu: 0.8% -2.0%, Al: 0.5 to 1.0 percent, and further ensures the corrosion resistance of the steel by adding 0.2 to 0.5 percent of Mo, 0.010 to 0.030 percent of RE, 0.02 to 0.3 percent of Ca or a compound form of the two on the basis of the component design. The steel can be applied to the marine climate environments with high temperature, high humidity and high salinity, but the related alloy elements are various, the alloy content is high (especially the content of Ni and Cu), and the alloy cost of the material is high.
Patent CN103741056A introduces a corrosion resistant steel plate for resisting the ocean environment of south China sea and a production process thereof. The alloy comprises the following components: 0.03-0.10%, Si: 0.1-1.0%, Mn: 0.5-1.5%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, Cu: 0.1-1.0%, Cr: 0.1 to 1.0%, Ni: 0.1-1.0%, Mo: 0.1-0.5%, Sn: 0.01-0.3%, Ti: 0.01-0.05%, Als: 0.01 to 0.05 percent; compared with CN106011658A, the alloy content of the steel is obviously reduced, the Ni content is reduced, the Cr content is increased, and the steel can be used in various south-sea marine environments (atmosphere, tidal range and full immersion). However, although the content of the alloying element is reduced and the cost of the alloy is reduced, the weldability and toughness of the steel material are lowered by including a high content of Sn element in the composition. In addition, TMCP is required to be carried out in the production of the steel plate, and the production process is complex.
Patent CN10629751A describes a high corrosion resistant low alloy steel suitable for high temperature coastal environment. The alloy comprises the following components of less than or equal to 0.07 percent of C, 0.20-0.35 percent of Si, Mn: 1.0-1.2%, P is less than or equal to 0.030%, S is less than or equal to 0.004-0.012%, Ni: 3.0% -3.5%, Cu: 0.4% -1.0%, Mo: 0.1-0.2 percent of Ti and less than or equal to 0.020 percent of Ti; the total content of the alloy of the steel is reduced compared with CN106011658A, Ni element is used as a main alloy element, Cu and Mo are used as auxiliary elements, and Sn element is not contained, so that the corrosion resistance of the steel can be ensured by the component design, and the mechanical property of the steel can be considered. However, this steel also requires Ti microalloying and water cooling during the production process, and is also complicated in production process.
Patent CN106282831A describes a high strength atmospheric corrosion resistant steel for containers. The component design is C: 0.03-0.10%, Si: 0.3-0.6%, Mn: 0.4-0.8%, P is less than or equal to 0.015%, S is less than or equal to 0.006%, Al is less than or equal to 0.05%, Cu: 0.2-0.4%, Cr: 0.4-0.9%, Ti: 0.06-0.12%, Ca: 0.001-0.006 percent of N, less than or equal to 0.006 percent of N; on the basis of lower C-Mn steel components, the corrosion resistance is ensured by adding a small amount of Cr and Cu, and the strength of the steel is ensured to reach more than 450-550MPa by forming a complex phase structure of ferrite and a small amount of bainite through Ti microalloying and combining TMCP. Its advantages are less kinds of alloy elements, low total content of alloy and low cost. However, this steel is not suitable for long-term service in tropical marine environments, and Ti microalloying needs to be combined with N element, which increases the difficulty of process control, and the production process of this steel is more complicated by using TMCP process.
Patent CN106929763A introduces an economical corrosion-resistant steel for coating in severe marine environment, the alloy composition is designed to be C less than or equal to 0.1%, Si is 0.20-0.35%, Mn: 1.4-1.8%, P is less than or equal to 0.030%, S is less than or equal to 0.012%, Ni: 1.5% -3.0%, Cu: 0.2% -0.4%, Mo: 0.02-0.08 percent of Al or Ca, 0.2-0.5 percent of Al or Ca, less than or equal to 0.010-0.020 percent of Ti, wherein the total mass percent of corrosion resistant elements Cu, Ni, Mo, Al and Ca can be controlled to be 2.0-3.5 percent. The steel has good under-film corrosion resistance, can obviously prolong the service life of a coating when being combined with the coating, and can not obviously improve the cost. But the strength of the steel is ensured by Ti micro-alloying.
The invention relates to low-alloy corrosion-resistant steel applied to marine atmospheric environment, the main alloy elements are Ni, Cr, Cu, Mo, Al, Sn and the like, the alloy content is high, and part of steel relates to Sn, so that the alloy cost of materials can be reduced, but the weldability, the strength and the toughness of the steel are adversely affected. In addition, the strength of the material is ensured by Ti microalloying, and in the aspect of production process, the strength of the low alloy steel is ensured by TMCP or water cooling after rolling, so that the production process is complex.
Disclosure of Invention
In view of the above problems, the present invention has been made in order to provide a low alloy corrosion resistant steel of 420MPa class, a method of manufacturing the same, and applications thereof, which overcome or at least partially solve the above problems.
The embodiment of the invention provides 420 MPa-grade low-alloy corrosion-resistant steel which comprises the following chemical components in percentage by weight: c: 0.03-0.10%, Si: 0.01-1.0%, Mn: 1.0-2.1%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Al S is less than or equal to 0.02%, Cu: 0.1-0.6%, Ni: 0.2-4.0%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01% of Fe and inevitable impurities as the balance, wherein the contents of Ca, Mg and O in percentage by weight meet the following conditions: (Ca + Mg)/O is more than or equal to 1.0.
Further preferably, the metallographic structure of the low-alloy corrosion-resistant steel includes ferrite, pearlite and (bainite).
Further preferably, in the metallographic structure, the content of ferrite is 87-92%, the content of pearlite is 10-6%, and the content of bainite is 2-3% by volume percentage. .
Based on the same invention concept, the embodiment of the invention also provides a preparation method of 420 MPa-grade low-alloy corrosion-resistant steel, which comprises the following steps: smelting, casting blank heating, hot rolling and air cooling;
in the casting blank heating procedure, the temperature is 1150-1200 ℃;
in the hot rolling procedure, the final rolling temperature is 840-880 ℃, and the deformation of the final rolling pass is more than or equal to 20%.
Further preferably, in the smelting process, the million percent concentration of free oxygen in the molten steel is 10-100 ppm.
Further preferably, in the smelting step, when Mg and Ca are added to the molten steel, Mg — Ca alloy wires are fed to the molten steel for addition.
Further preferably, the diameter of the Mg-Ca alloy wire is 9-11 mm.
Based on the same invention concept, the embodiment of the invention also provides application of 420 MPa-grade low-alloy corrosion-resistant steel applied to Cl-The deposition rate is 0-0.4 mdd.
Further preferably, the Cl-The environment having a deposition rate of 0 to 0.4mdd includes at least one of: coastal atmosphere and south sea island reef atmosphere.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
1. according to the 420 MPa-grade low-alloy corrosion-resistant steel provided by the embodiment of the invention, alloy elements such as Cr, Mo and Sn are not required to be added, a small amount of Cu is assisted by a main corrosion-resistant alloy element Ni, and the form and size of inclusions are controlled by combining Mg-Ca treatment, so that the corrosion resistance of the low-alloy steel is further ensured. By the element design, micro-alloying and TMCP processes are not needed, the steel strength can be ensured by controlling the finish rolling temperature and the finish rolling reduction, the process production flow is simplified, the cost is reduced, and the large-scale industrial production is easy to realize.
2. The 420 MPa-grade low-alloy corrosion-resistant steel provided by the embodiment of the invention has the following properties:
1, excellent yield strength, wherein the yield strength is more than or equal to 420 MPa;
2, excellent low-temperature impact toughness, wherein the low-temperature impact toughness Akv-20 ℃ is more than or equal to 150J;
3 excellent corrosion resistance, can meet Cl-The deposition rate is 0-0.4mdd, and the corrosion resistance of the corrosive environment is required;
3. compared with the similar low-alloy corrosion-resistant steel, the 420 MPa-grade low-alloy corrosion-resistant steel provided by the embodiment of the invention has the advantage that the corrosion resistance is improved by 50%.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
In order to solve the technical problems, the principle of the technical scheme in the embodiment of the application is as follows:
the application provides 420 MPa-grade low-alloy corrosion-resistant steel which comprises the following chemical components in percentage by weight: c: 0.03-0.10%, Si: 0.01-1.0%, Mn: 1.0-2.1%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Als is less than or equal to 0.02%, Cu: 0.1-0.6%, Ni: 0.2-4.0%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01% of Fe and inevitable impurities as the balance, wherein the contents of Ca, Mg and O in percentage by weight meet the following conditions: (Ca + Mg)/O is more than or equal to 1.0.
Carbon: carbon is the most main element for tissue control, and can be in limited solid solution with gamma-Fe, so that an austenite phase region can be expanded to a certain extent; meanwhile, carbide formed by carbon and chromium is beneficial to improving the corrosion resistance, but the content of cementite Fe3C in steel is increased due to the excessively high content of carbon, so that the content of pearlite is increased, and the corrosion resistance of the alloy is reduced; on the other hand, the increase of the carbon content is not beneficial to the weldability of the material, and in order to avoid the adverse effect of the carbon, the carbon content should be controlled between 0.04 and 0.15 percent;
silicon: the silicon has the functions of deoxidation and strength guarantee, and simultaneously, the silicon can be enriched in a surface film to improve the passivation performance of the steel, but the welding performance of the steel is reduced when the silicon content is too high, and the minimum strength cannot be guaranteed when the silicon content is too low, so the silicon content is controlled within 0.1-1.0%;
manganese: the manganese is the same as the silicon and mainly has the functions of deoxidation and strength guarantee, and the manganese can weaken the brittleness of the alloy caused by sulfur and improve the processing performance of steel; manganese is an austenite phase region enlarging element and delays the transformation from austenite to ferrite; meanwhile, manganese belongs to a weak carbide forming element, and needs to form alloy cementite with higher manganese content during structure transformation, so that nucleation and growth of the alloy cementite during pearlite transformation can be slowed down, but when the manganese content is higher than 2%, crystal grains can be coarsened obviously, and the low-temperature toughness of the steel is also reduced obviously. In addition, the Mn and C contents are required to satisfy Mn/C ≧ 14.0, which is an important control factor in the present invention, and this is mainly based on the new findings in this study: when the Mn/C ratio is less than 14.0, a small amount of granular bainite structures are obtained in the structure, and the corrosion resistance of the steel is remarkably reduced.
Sulfur: sulfur is an indispensable element in alloy smelting, but sulfur is not only unfavorable to the strength and welding performance of steel, but also easily dissolved in an acid environment, easily forms inclusions, induces pitting corrosion and reduces the corrosion resistance of the material, so the lower the sulfur content is, the better the corrosion resistance is, the lower the sulfur content is generally controlled below 0.005 percent;
phosphorus: phosphorus is a ferrite phase region forming element and can be in limited solid solution with alpha-Fe to narrow an austenite phase region; meanwhile, phosphorus is beneficial to improving the corrosion resistance of the material in an acid soil environment, and phosphorus is used as an anode depolarizer and is beneficial to forming a uniform rust layer on the surface of steel so as to inhibit corrosion, but the welding performance is deteriorated and the toughness is reduced due to the excessively high content of phosphorus, so that the content of phosphorus is controlled to be below 0.1%;
aluminum: the aluminum mainly plays a role of deoxidation, but the aluminum content is too high, so that alumina inclusions in steel are easily increased and become a corrosion source, and the content of the aluminum is controlled to be below 0.02 percent;
nickel: nickel is one of the most important elements for improving the corrosion resistance of low alloy steel. It is believed that the addition of Ni to the steel provides cation selective permeability to the low alloy steel rust layer, thereby preventing Cl "from penetrating through the rust layer to contact the substrate and improving the corrosion resistance of the low alloy steel. When the Ni content is less than 3.5%, the resistance of the low alloy steel increases linearly with the increase in the Ni content in the steel, but the increase in the corrosion resistance of the low alloy steel decreases significantly with a further increase in the Ni content. Therefore, the invention stipulates that the Ni content is 0.2-4.0%
Copper: copper plays an important role in improving the corrosion resistance of low alloy steel, generally, the corrosion resistance of steel can be improved when 0.06% -0.10% of copper is added into the steel, the corrosion resistance which is obviously superior to that of carbon steel can be obtained when 0.12% -0.14% of Cu is added into weather-resistant steel, and CuO is formed in a rust layer when the copper content is less than 0.5%, so that the compactness of the rust layer is changed, the electrochemical reaction is inhibited, and the corrosion resistance of the low alloy steel is improved. When the copper content is more than 0.5%, part of copper forms elementary copper precipitation particles in the steel, which has a certain effect on improving the strength of the low alloy steel but is unfavorable for toughness, so the addition amount of copper is proper. The invention therefore provides for a Cu content of between 0.1% and 0.6%.
Magnesium, calcium, oxygen are key elements in the present invention. Magnesium and calcium are strong deoxidizing elements in steel, and are combined with oxygen in the steel to form fine composite spherical oxide particles, and the composite particles can better form long-strip MnS and nonstandard Al in the steel2O3The formation of inclusions improves the corrosion resistance of the steel. Meanwhile, the grain size of ferrite is refined by the composite oxide particles, and the low-temperature toughness of the material is obviously improved. In order to ensure the precipitation of a large amount of fine particles, the lower limits of magnesium, calcium and oxygen are controlled to be 0.001 percent. However, excessive magnesium, calcium and oxygen can increase the amount of oxide inclusions in the steel, increase the size, obviously reduce the corrosion resistance of the low alloy steel in the tropical marine atmospheric environment, cannot play a role in refining the structure in the steel, and reduce the low-temperature toughness of the steel. Therefore, the upper limits of the contents of magnesium, calcium and oxygen in the steel are all controlled to be 0.01%. Meanwhile, when (Ca + Mg)/O is more than or equal to 1, the amount of the oxide formed in the steel is large, the size is small, the final microstructure is obviously refined, and the corrosion resistance and the low-temperature toughness are improved.
In this embodiment, the metallographic structure of the low-alloy corrosion-resistant steel includes ferrite, pearlite, and (bainite).
In the embodiment, the metallographic structure contains, by volume, 87-92% of ferrite, 10-6% of pearlite and 2-3% of bainite.
Based on the same invention concept, the embodiment of the invention also provides a preparation method of 420 MPa-grade low-alloy corrosion-resistant steel, which comprises the following steps: smelting, casting blank heating, hot rolling and air cooling;
in the casting blank heating procedure, the temperature is 1150-1200 ℃, and the temperature is kept for 2 hours;
in the hot rolling procedure, the final rolling temperature is 840-880 ℃, and the deformation of the final rolling pass is more than or equal to 20%.
And after the rolling is finished, air cooling to room temperature.
The purpose of the control range of the heating temperature of the casting blank is 1150-1200 ℃ is to prevent the overheating or overburning phenomenon of the casting blank caused by overhigh heating temperature and simultaneously prevent the generation of austenite grains with coarse grain size. The purpose of controlling the finish rolling temperature and the deformation of the finish rolling pass is to improve the strength of steel, increase the content of a deformation zone in austenite grains through low temperature and large deformation, and refine the grain size of ferrite.
In the smelting process, the million percent concentration of free oxygen in molten steel is 10-100 ppm.
A small amount of free oxygen in the steel can improve the pitting corrosion induction resistance of the low alloy steel to a certain extent, but the mechanical property of the steel is obviously influenced by the high content of the free oxygen. Therefore, the free oxygen content in the steel is controlled to be 10-100 ppm.
In the smelting process, when Mg and Ca are added into molten steel, Mg-Ca alloy wires are fed into the molten steel for adding.
The purpose of adopting the calcium-magnesium alloy wire is as follows: 1. modifying the inclusions to enable the inclusions to wrap CaO; 2. the MgO plays a role in oxide metallurgy, and grains are refined. However, the calcium-magnesium alloy wire treatment is a half method for smelting corrosion-resistant steel and is not the core content of the patent
In this example, the diameter of the Mg-Ca alloy wire is 9 to 11 mm.
Based on the same invention concept, the application also provides application of 420 MPa-grade low-alloy corrosion-resistant steel applied to Cl-The deposition rate is 0-0.4 mdd.
In this example, the Cl-The environment having a deposition rate of 0 to 0.4mdd includes at least one of: coastal atmospheric environment and south sea island reef atmospheric ringAnd (4) environmental conditions.
The low-alloy corrosion-resistant steel produced by the scheme is applied to coastal atmosphere, coating-free application and coating-reduction application can be realized on the basis of traditional weathering steel and carbon steel, the corrosion resistance of surface coating application is stronger than that of the traditional weathering steel, and the coating application reduces the coating dosage under the condition of ensuring the service life of a steel structure. When the coating is applied to the position of the island in south China sea, the low-alloy corrosion-resistant steel can prolong the service life of the coating in the coating application environment, so that the whole service life of a protection system of the corrosion-resistant steel and the coating is prolonged.
The 420MPa grade low alloy corrosion resistant steel of the present application, its preparation method and application will be described in detail with reference to the following specific examples.
The chemical composition weight percentage contents of the low alloy corrosion resistant steels in examples 1-10 and the steels in comparative examples 1-5 are shown in table 1.
TABLE 1
Figure GDA0002468017220000061
Figure GDA0002468017220000071
Example 11
The embodiment provides a preparation method of 420 MPa-grade low-alloy corrosion-resistant steel, which comprises the following steps: smelting, casting blank heating, hot rolling and air cooling;
in the casting blank heating procedure, the temperature is 1170 ℃;
in the hot rolling procedure, the final rolling temperature is 860 ℃, and the deformation of the final rolling pass is 10%.
In the smelting process, the million percent concentration of free oxygen in molten steel is 50 ppm.
In the smelting process, when Mg and Ca are added into molten steel, 10mm Mg-Ca alloy wires are fed into the molten steel for adding.
Example 12
The embodiment provides a preparation method of 420 MPa-grade low-alloy corrosion-resistant steel, which comprises the following steps: smelting, casting blank heating, hot rolling and air cooling;
in the casting blank heating procedure, the temperature is 1150 ℃;
in the hot rolling procedure, the final rolling temperature is 840 ℃, and the deformation of the final rolling pass is 20%.
In the smelting process, the million percent concentration of free oxygen in the molten steel is 10 ppm.
In the smelting process, when Mg and Ca are added into molten steel, 9mm Mg-Ca alloy wires are fed into the molten steel for adding.
Example 13
The embodiment provides a preparation method of 420 MPa-grade low-alloy corrosion-resistant steel, which comprises the following steps: smelting, casting blank heating, hot rolling and air cooling;
in the casting blank heating procedure, the temperature is 1200 ℃;
in the hot rolling process, the final rolling temperature is 880 ℃, and the deformation of the final rolling pass is 30%.
In the smelting process, the million percent concentration of free oxygen in molten steel is 100 ppm.
In the smelting process, when Mg and Ca are added into molten steel, 11mm Mg-Ca alloy wires are fed into the molten steel for adding.
Experimental example 1
The low alloy corrosion-resistant steels of examples 1 to 10 were prepared using the preparation method of example 11, and the mechanical properties and corrosion resistance of the prepared low alloy corrosion-resistant steels of examples 1 to 10 and steels of comparative examples 1 to 5 were measured, and the results of the measurements are shown in table 2.
The method for detecting the corrosion resistance comprises the following steps: the salt spray method is adopted to test the marine atmospheric corrosion resistance, and the solution is prepared by using distilled water and NaCl and NaSO4And CaCl2The artificially prepared mass fraction is 0.1 percent of NaCl and 0.05 percent of NaSO4+0.05％CaCl2The solution is at the ambient temperature of 30 ℃ and the corrosion time is 336 h.
TABLE 2
Figure GDA0002468017220000081
Figure GDA0002468017220000091
In the context of Table 2, the following examples are,
the comparative example 1 is the traditional carbon steel, the chemical components and the (Ca + Mg)/O control do not meet the requirements of the invention, and the corrosion resistance is the worst;
comparative example 2 the corrosion resistance of the traditional weathering steel is improved by about 30 percent compared with the corrosion resistance of the carbon steel;
comparative example 3 corrosion resistant steel has a slightly lower copper content and slightly poorer corrosion resistance;
comparative example 4 corrosion-resistant steel has low nickel content and poor corrosion resistance;
comparative example 5 (Ca + Mg)/O control of the corrosion-resistant steel does not meet the requirements, inclusions in the steel are not effectively controlled, and the corrosion resistance is poor;
as can be seen from Table 2, the annual average corrosion rate was reduced for each example as compared to the comparative example material. The chemical compositions of the materials of the examples, the control of inclusions and the like are claimed, and the corrosion resistance service life of the materials of the comparative examples can be obviously prolonged.
The low-alloy corrosion-resistant steel material for tropical marine atmosphere in the embodiment of the invention has obviously better marine atmospheric corrosion resistance than the traditional weathering steel and carbon steel on the basis of not reducing the mechanical property of the material. The corrosion resistance of the product in tropical marine atmospheric corrosion environment can be greatly improved by controlling the content of alloy elements and inclusion, so that the cost of the product is not greatly improved, the service life is obviously prolonged, the industrial production is very easy to realize, and the product has wide application prospect.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (2)

1. The 420 MPa-grade low-alloy corrosion-resistant steel is characterized by comprising the following chemical components in percentage by weight: c: 0.03-0.10%, Si: 0.01-1.0%, Mn: 1.0-2.1%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Als is less than or equal to 0.02%, Cu: 0.1-0.6%, Ni: 0.2-4.0%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01% of Fe and inevitable impurities as the balance, wherein the contents of Ca, Mg and O in percentage by weight meet the following conditions: (Ca + Mg)/O is more than or equal to 1.0; the metallographic structure of the low-alloy corrosion-resistant steel comprises ferrite, pearlite and bainite; in the metallographic structure, the ferrite content is 87-92%, the pearlite content is 10-6%, and the bainite content is 2-3%;
the preparation method of the 420 MPa-grade low-alloy corrosion-resistant steel comprises the following steps: smelting, casting blank heating, hot rolling and air cooling;
in the casting blank heating procedure, the temperature is 1150-1200 ℃;
in the hot rolling procedure, the final rolling temperature is 840-880 ℃, and the deformation of a final rolling pass is more than or equal to 20%;
in the smelting process, the million percent concentration of free oxygen in molten steel is 10-100 ppm;
in the smelting process, when Mg and Ca are added into molten steel, Mg-Ca alloy wires are fed into the molten steel for adding;
the diameter of the Mg-Ca alloy wire is 9-11 mm;
the 420 MPa-grade low-alloy corrosion-resistant steel is applied to Cl-The deposition rate is 0-0.4 mdd.
2. The 420MPa grade low alloy corrosion resistant steel of claim 1, wherein the Cl is-The environment having a deposition rate of 0 to 0.4mdd includes at least one of: coastal atmosphere and south sea island reef atmosphere.
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