CN112080689A - Steel for wheel and preparation method thereof - Google Patents
Steel for wheel and preparation method thereof Download PDFInfo
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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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
- B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
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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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- 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
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- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
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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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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- 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
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- 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
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Abstract
The invention relates to steel for a wheel and a preparation method thereof, wherein the steel for the wheel comprises the following chemical components in percentage by mass: c is more than or equal to 0.055% and less than or equal to 0.070%, Si is more than or equal to 0.70% and less than or equal to 0.85%, Mn is more than or equal to 1.45% and less than or equal to 1.55%, Al is more than or equal to 0.030% and less than or equal to 0.050%, P is less than or equal to 0.015%, S is less than or equal to 0.002%, N is less than or equal to 0.045%, O is less than or equal to 0.0020%, the total content of Cr and Nb is 0.20-0.40%, and the balance. The strength is higher, the toughness and plasticity are worse, for the wheel steel with higher strength, the strength and toughness matching are ensured to be a key point, in the prior art, a large amount of Nb, V and Ti alloy is added to ensure the strength and toughness and plasticity, the production process adopts low-C and low-alloy Cr and Nb to obtain the wheel steel with good comprehensive performance, and on the basis of not adding a large amount of Nb, V, Ti and other alloys, the excellent performance is ensured, the qualification rate is high, and the production cost is reduced.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to steel for a wheel and a preparation method thereof.
Background
With the ever-increasing economic demand of China, the demand of people on automobiles is continuously increased, the use safety and the economic performance are concerned and paid more attention, the light weight of the automobiles is the development direction of the automobiles all over the world, compared with cold-rolled automobile plates, hot-rolled wheel steel is thicker and heavier, so the weight reduction effect is more obvious, and the steel for the wheel is the first place among parts needing weight reduction.
At present, high-strength wheels with tensile strength of 550MPa to 600MPa are widely applied in developed countries such as the United states, Japan and the like, and the high-strength steel share in North America reaches even 90%. The high-strength wheel steel used in China is few, most wheel steel produced in various steel plants is in the trial stage, the highest strength of mass production is 590MPa, a low-C, low-S, Nb and Ti composite component system is adopted, the structure is mainly ferrite and martensite, but the higher strength is needed to be developed for the light weight of the wheel steel.
Therefore, there is a need for developing a steel for wheel and a preparation method thereof, which can improve the strength of the steel for wheel on the basis of the prior art, so that the steel for wheel has the advantages of reduced thickness, reduced weight, better safety performance and high strength and light weight.
Disclosure of Invention
The present invention is directed to solving one of the technical problems of the prior art or the related art.
One aspect of the present invention provides a steel for a wheel.
The invention also provides a preparation method of the steel for the wheel.
In view of the above, one aspect of the present invention provides a steel for a wheel, which comprises the following chemical components by mass:
c is more than or equal to 0.055% and less than or equal to 0.070%, Si is more than or equal to 0.70% and less than or equal to 0.85%, Mn is more than or equal to 1.45% and less than or equal to 1.55%, Al is more than or equal to 0.030% and less than or equal to 0.050%, P is less than or equal to 0.015%, S is less than or equal to 0.002%, N is less than or equal to 0.045%, O is less than or equal to 0.0020%, the total content of Cr and Nb is 0.20-0.40%, and the balance.
Further, the thickness of the steel for the wheel is not more than 6 mm.
Furthermore, the yield strength of the steel for the wheel is 547MPa to 553MPa, the tensile strength is 716MPa to 724MPa, and the elongation is 26 percent to 29 percent, so that the steel for the wheel is manufactured into the wheel rim.
The invention also provides a preparation method of the steel for the wheel, which comprises the following steps of steel making, heating in a heating furnace, hot continuous binding, controlled cooling, coiling and functional inspection, wherein the steel making step comprises the following steps:
pretreating molten iron: desulfurizing the molten iron to ensure that S is less than or equal to 0.003 percent, and skimming slag;
a converter process: the method comprises the following steps of (1) loading fine material scrap steel into a furnace, pouring the treated molten iron into the furnace to form molten steel, blowing a steel ladle through argon before tapping, and injecting the molten steel into the steel ladle to ensure that Alt is more than or equal to 0.015% and less than or equal to 0.030% and N is less than or equal to 25ppm in the steel ladle;
an external refining process: refining the molten steel in the ladle to ensure that the nitrogen increment N is less than or equal to 10ppm, manufacturing reducing slag with fluidity, controlling argon blowing strength, and performing calcium treatment to obtain refined molten steel;
and (3) continuous casting process: pouring the refined molten steel into a tundish, purging the tundish by using argon before casting to ensure that the nitrogen increment N is less than or equal to 5ppm, removing impurities in the steel by using high-alkalinity tundish slag, and controlling the superheat degree of continuous casting to be not more than 25 ℃;
wherein 1ppm is 0.0001%.
Further, the converter process also comprises the step of blowing oxygen into a molten pool in the converter, when the carbon content in the molten pool meets the tapping requirement, the oxygen blowing is stopped, and high manganese and ferrosilicon are added before tapping.
Further, the external refining process adopts an LF + RH double-path process, wherein an LF path is heated by an electrode to perform desulfurization and temperature adjustment, and an RH path is used for degassing and decarburization;
wherein, the LF route adopts active lime and fluorite to manufacture reducing slag with fluidity.
Further, the heating temperature in the heating furnace is 1200-1270 ℃, the heating time is 2.5 hours, and the heat preservation time is 30 min.
Further, the hot continuous rolling process comprises rough rolling and finish rolling, wherein the initial rolling temperature of the rough rolling is not lower than 1080 ℃, and the final rolling temperature of the finish rolling is 820-900 ℃.
Further, the coiling temperature at the coiling time is 450 ℃ to 550 ℃.
Further, the control cooling adopts interval cooling.
The technical scheme provided by the embodiment of the invention can have the following beneficial effects:
the strength is improved through Cr and Nb elements, the steel for the wheel is ensured to form ferrite and bainite structures, the excellent matching of the strength and the toughness and the plasticity is achieved through the ferrite and the bainite structures, the ferrite has low strength and good toughness, and the bainite has high strength and poor toughness; the refining path of the LF and RH dual path is adopted, so that the S, P content is lower, and the inclusion is improved by adopting calcium treatment, so that the purity of the molten steel is ensured; the Cr and Nb elements are used for replacing Nb, V and Ti elements, so that the strength is ensured and the production cost is reduced.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a schematic flow chart illustrating a method for manufacturing a steel for a wheel according to an embodiment of the present invention;
FIG. 2 shows a schematic flow diagram for making steel according to one embodiment of the present invention.
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the invention, as detailed in the appended claims.
The invention provides steel for a wheel, which comprises the following chemical components in percentage by mass:
c is more than or equal to 0.055% and less than or equal to 0.070%, Si is more than or equal to 0.70% and less than or equal to 0.85%, Mn is more than or equal to 1.45% and less than or equal to 1.55%, Al is more than or equal to 0.030% and less than or equal to 0.050%, P is less than or equal to 0.015%, S is less than or equal to 0.002%, N is less than or equal to 0.045%, O is less than or equal to 0.0020%, the total content of Cr and Nb is 0.20-0.40%, and the balance.
The strength is higher, the toughness and plasticity are worse, for the wheel steel with higher strength, the strength and toughness matching are ensured to be a key point, in the prior art, a large amount of Nb, V and Ti alloy is added to ensure the strength and toughness and plasticity, the production process adopts low-C and low-alloy Cr and Nb to obtain the wheel steel with good comprehensive performance, and on the basis of not adding a large amount of Nb, V, Ti and other alloys, the excellent performance is ensured, the qualification rate is high, and the production cost is reduced.
Wherein, C is the main element determining the strength, the more the content is, the higher the strength is, but the too high content reduces the plasticity and impact toughness of the steel, deteriorates the cold formability and the weldability, so the content of C in the steel should be reduced as much as possible on the premise of ensuring the strength.
Si has strong affinity with oxygen, belongs to strong deoxidizing elements and exists in steel in a solid solution form, can improve the strength, fatigue limit, corrosion resistance and wear resistance of the steel, but has high content, is easy to generate oxides during hot rolling, and reduces the surface quality of steel.
Mn exists in a solid solution state in steel, belongs to a solid solution strengthening element, and can increase the strength of ferrite, but an excessive amount thereof lowers the toughness and weldability of the steel.
S is a harmful element, which causes hot brittleness of steel, reduces toughness and plasticity of the steel, is easy to form cracks when a finished product is subjected to a forming test and a stamping test, and reduces the content of S as much as possible during production.
The strength of the steel is affected by the excessive content of N, so that the strength is low, and the content of N is reduced as much as possible during production.
Low O content, less inclusion and high toughness and plasticity.
Further, Nb is added to promote grain refinement, so that the toughness is slowly increased while the strength is improved; the Cr element is added, so that the strength, hardness and wear resistance of the steel can be obviously improved.
Further, the thickness of the steel for wheel is not more than 6 mm.
Furthermore, the yield strength of the steel for the wheel is 547MPa to 553MPa, the tensile strength is 716MPa to 724MPa, and the elongation is 26 percent to 29 percent, so that the steel for the wheel rim is manufactured.
The yield strength of the steel for the wheel is not less than 500MPa, the tensile strength is 650MPa to 750MPa, the elongation is not less than 20%, and the steel for the tough wheel with the chemical components can meet the requirements.
FIG. 1 is a schematic flow chart illustrating a method for manufacturing a steel for a wheel according to an embodiment of the present invention; FIG. 2 shows a schematic flow diagram for making steel according to one embodiment of the present invention.
As shown in fig. 1 and 2, another aspect of the present invention provides a method for preparing steel for a wheel, including a steel-making process → heating in a heating furnace → a hot continuous bonding process → controlled cooling → coiling → functional inspection, wherein the steel-making process includes:
step 101, pretreating molten iron: desulfurizing the molten iron to ensure that S is less than or equal to 0.003 percent, and skimming slag;
step 102, a converter process: the refined scrap steel is loaded into a furnace, the treated molten iron is poured into the furnace to form molten steel, a steel ladle is swept by argon before tapping, the molten steel is injected into the steel ladle, and Alt is more than or equal to 0.015% and less than or equal to 0.030% in the steel ladle and N is less than or equal to 25 ppm;
step 103, an external refining process: refining the molten steel in the ladle to ensure that the nitrogen increment N is less than or equal to 10ppm, manufacturing reducing slag with fluidity, controlling argon blowing strength, and performing calcium treatment to obtain refined molten steel;
step 104, a continuous casting process: introducing refined molten steel into a tundish, purging the tundish by adopting argon before casting to ensure that the nitrogen increment N is less than or equal to 5ppm, removing impurities in the steel by adopting high-alkalinity tundish slag, and controlling the superheat degree of continuous casting to be not more than 25 ℃;
wherein 1ppm is 0.0001%.
It is to be noted that Al in steel is divided into acid-soluble aluminum and acid-insoluble aluminum, Alt represents the total aluminum content in steel, the content of aluminum measured in factories and mines is the acid-soluble aluminum content, and the total aluminum Alt content is adopted to represent in the process production process; pouring the refined molten steel into a tundish, dividing the molten steel into a plurality of small flows by the tundish, entering a condenser, solidifying and then changing into a billetThe slag ladle has the advantages of heat preservation, prevention of overlarge temperature drop of molten steel in the pouring process, prevention of secondary oxidation of the molten steel, capability of adsorbing floating impurities and no pollution to the molten steel, wherein the high-alkalinity slag ladle mainly adopts MgO or dolomite as a base material, does not increase the content of C, and has better capacity of adsorbing the impurities, and the adsorbed impurities comprise Al2O3MnS, FeS, etc.
The calcium wire is fed into the molten steel, so that the form of inclusions is improved, the purity of the molten steel is ensured, and the strength and the quality of the steel for the wheel are improved.
Specifically, the external refining is to transfer the primarily refined molten steel in the converter to another container for refining, the furnace burden is melted, dephosphorized, decarburized and subjected to main alloying in the oxidizing atmosphere furnace during the primary refining in the converter, and the primarily refined molten steel is subjected to degassing, deoxidation and desulfurization in a vacuum, inert gas or reducing atmosphere container during the external refining, so as to remove impurities, and then the composition fine adjustment, the molten steel temperature adjustment and the process buffering are carried out, so that the requirements of the subsequent continuous casting are met.
The strength is improved through Cr and Nb elements, the steel for the wheel is ensured to form ferrite and bainite structures, the excellent matching of the strength and the toughness and the plasticity is achieved through the ferrite and the bainite structures, the ferrite has low strength and good toughness, and the bainite has high strength and poor toughness; the refining path of the LF and RH dual path is adopted, so that the S, P content is lower, and the inclusion is improved by adopting calcium treatment, so that the purity of the molten steel is ensured; the Cr and Nb elements are used for replacing Nb, V and Ti elements, so that the strength is ensured and the production cost is reduced.
Furthermore, in the production process, on the premise of ensuring the strength of the steel for the wheel, the steel for the wheel has the advantages of reduced thickness and weight, and meets the requirements of users.
The method comprises the following steps of carrying out protective pouring in the whole continuous casting process, purging a tundish by adopting argon before pouring, wherein no molten steel is exposed in the pouring process, the water mouth is strictly controlled to absorb N, and the nitrogen increment is controlled to be less than or equal to 5 ppm.
It should be noted that the steel casting process is performed by using a soft reduction function, the steel casting process is kept at a constant drawing speed, and the secondary cooling adopts a weak cooling mode.
Specifically, the soft reduction is a process method for applying small pressure to a liquid-cored casting blank in order to obtain a defect-free casting blank when the continuous casting and rolling blank is subjected to liquid core straightening in the continuous casting and iron making process, wherein solidification and cooling shrinkage can cause solidification shrinkage force to suck S, P enriched liquid among dendritic crystals at the periphery to generate center segregation, the center segregation is formed because an inward-growing solidification front forms a bridge to obstruct downward delivery of molten steel, and the center segregation can seriously influence the internal quality of the casting blank. In order to reduce the center segregation, a soft reduction technology is applied to a section (casting blank solidification end section) where the center segregation is generated, that is, a casting blank is slightly reduced at a position where the casting blank is nearly completely solidified, so that the center segregation is reduced.
Wherein the constant drawing speed is generally 1m/min to 4 m/min; the secondary cooling is a secondary cooling area, primary water spray cooling is carried out when the continuous casting billet just comes out, secondary cooling is generally carried out at a bending arc, the secondary cooling is carried out at the section, the weak cooling mode is compared with the strong cooling of a primary cooling area, the water quantity is reduced, and the cooling strength is reduced.
The steel for the wheel, which is produced by the preparation method, has excellent comprehensive performance, particularly has better matching degree on strength and toughness, has better safety performance, can meet the use requirements of users, and improves the economy of enterprises.
Wherein the heating temperature in the heating furnace is 1200-1270 ℃, the heating time is 2.5 hours, and the heat preservation time is 30 min.
The heating time is 2.5 hours, the heat preservation time is 0.5 hour, the total furnace time is 3 hours, and if the heating time is too long, particularly the residence time in a high-temperature region is too long, the defects of overheating, overburning, decarburization, oxidation and the like can be caused; if the heating time is short, the problems of low steel temperature, uneven temperature and the like can be caused.
If the heating temperature is too high, the surface of the steel billet can be melted; if the heating temperature is too low, the grain structure in the billet cannot be fully austenitized, and cracks can appear in the billet during rolling, so that the heating temperature is 1200-1270 ℃, the full fusion of alloy elements is ensured, the high-strength steel has better plasticity and good plate shape during rolling, and the requirements of the rolling process are met.
Further, the hot continuous rolling process comprises rough rolling and finish rolling, wherein the initial rolling temperature of the rough rolling is not lower than 1080 ℃, and the final rolling temperature of the finish rolling is 820-900 ℃.
The rough rolling pass is controlled by selecting a 3+3 mode, namely two rough rolling mills are included during production, 3 passes (past-return-past) are rolled on each rough rolling mill, the load distribution of a finish rolling model is well done, and the rolling stability is ensured.
Further, the coiling temperature at the time of coiling is 450 ℃ to 550 ℃.
The coiling temperature is 450-550 ℃, and the steel for the wheel with ferrite and bainite structures can be obtained.
The finish rolling temperature of 820-900 ℃ and the coiling temperature of 450-550 ℃ are adopted, so that the steel for the wheel obtains a ferrite and bainite structure, and has better stretch flangeability and better welding performance compared with the ferrite and martensite structure.
It should be noted that the bainite transformation temperature is generally below 600 ℃, the transformation temperatures of different components are different, and the production process is basically completely transformed at 450 ℃ to 550 ℃.
Further, the converter process also comprises the steps of blowing oxygen into a molten pool in the converter, stopping blowing oxygen when the carbon content in the molten pool meets the tapping requirement, and adding high manganese and ferrosilicon before tapping.
When the carbon content in the molten pool reaches the tapping requirement, the oxygen blowing is stopped, at the blowing end point, the sulfur, phosphorus, temperature and the like of the molten pool meet the tapping requirement, the carbon in the molten pool and the carbon brought by the ferroalloy can also meet the requirement of the steel type to be smelted, and a special carburant for recarburization is not needed to be added to the metal, so that the metal yield is high, the ferromanganese consumption is low, the FeO in the slag is low, the furnace life is favorably improved, and the gas and impurity content in the steel is low.
Wherein, the high manganese and the ferrosilicon are added before tapping to ensure that the Mn content and the Si content meet the design requirements so as to meet the use requirements of the steel for the wheels.
Further, the external refining process adopts an LF + RH double-path process, wherein an LF path is heated by an electrode to perform desulfurization and temperature adjustment, and an RH path is used for degassing and decarburization;
wherein, the LF route adopts active lime and fluorite to manufacture reducing slag with fluidity.
Specifically, the LF path is mainly used for desulfurization and temperature regulation, and the LF is a ladle refining furnace which is heated by electrodes to perform component desulfurization and the like and temperature regulation; the RH route is mainly used for degassing (hydrogen, etc.) and decarburization, belongs to vacuum refining equipment, has short treatment time, is generally used for producing steel with high quality or high performance requirement, and is used when the requirement on the steel quality is high.
Wherein, lime and fluorite adjust the slag condition, can make the reduction slag have good fluidity and appropriate alkalinity, have fine effect to the desulfurization.
Adopting an LF + RH double-path process to obtain pure molten steel, wherein the LF treatment process is required to keep micro-positive pressure, the LF increase N is strictly controlled, the increase N amount is required to be less than or equal to 10ppm, the argon blowing strength is strictly controlled, and the molten steel is prevented from being exposed as much as possible; calcium treatment is adopted, so that inclusions are fully spheroidized, and the product performance is improved.
Further, the controlled cooling employs interval cooling.
Specifically, in actual production, the intermediate-section cooling is adopted, namely the water spraying cooling after finish rolling is carried out adopts a mode of spraying water at intervals of one group.
The steel for the wheel of the application forms a ferrite + bainite structure in the machining process, Cr is added as an alloy element to prevent the formation of Fe3C, Cr is a carbide forming element with medium strength and has the function of delaying the transformation of pearlite and bainite, Cr can improve the stability of super-cooled austenite in a high-temperature transformation region, particularly a low-temperature transformation region, the incubation period is prolonged, a curve moves rightwards, and a stable ferrite + bainite structure is formed.
Comparative example
TABLE 1 comparison of properties and weights of sample steels
The sample 1 is the steel for the wheel manufactured by the method, the process of the sample 2 is the performance parameter of the previous generation RS590 product, the composition is the same as that of the sample 1, but the content is different, under the condition of meeting the national standard of various parameters of the steel for the wheel, the weight is reduced by 11%, the sample 3 is 590MPa grade wheel steel, the Nb and Ti are adopted for reinforcement, wherein the Nb content is higher than 0.020% of the Nb content of the sample 1, the Ti content is 0.025%, the yield strength is only slightly higher than that of the sample 1 in performance, the tensile strength and the elongation are both lower than that of the sample 1, in addition, the sample 3 adopts Nb and Ti with higher cost, so the cost is higher than that of the sample 1, and the production cost of the steel for the wheel is reduced on the premise that the strength grade of the sample 1 can be ensured.
As can be seen from Table 1, the steel for wheel using the chemical composition and the preparation method of the invention has better performance parameters, and can reduce the weight and the production cost of the steel for wheel.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It is to be understood that the present invention is not limited to what has been described above, and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (10)
1. The steel for the wheel is characterized by comprising the following chemical components in percentage by mass:
c is more than or equal to 0.055% and less than or equal to 0.070%, Si is more than or equal to 0.70% and less than or equal to 0.85%, Mn is more than or equal to 1.45% and less than or equal to 1.55%, Al is more than or equal to 0.030% and less than or equal to 0.050%, P is less than or equal to 0.015%, S is less than or equal to 0.002%, N is less than or equal to 0.045%, O is less than or equal to 0.0020%, the total content of Cr and Nb is 0.20-0.40%, and the balance.
2. The steel for wheel according to claim 1, wherein the steel for wheel has a thickness of not more than 6 mm.
3. The steel for wheel according to claim 1, wherein the steel for wheel has a yield strength of 547 to 553MPa, a tensile strength of 716 to 724MPa, and an elongation of 26 to 29%.
4. A manufacturing method of the steel for wheel according to any one of claims 1 to 3, comprising a steel-making process → heating in a heating furnace → hot continuous binding process → controlled cooling → coiling → functional inspection, wherein the steel-making process comprises:
pretreating molten iron: desulfurizing the molten iron to ensure that S is less than or equal to 0.003 percent, and skimming slag;
a converter process: the method comprises the following steps of (1) loading fine material scrap steel into a furnace, pouring the treated molten iron into the furnace to form molten steel, blowing a steel ladle through argon before tapping, and injecting the molten steel into the steel ladle to ensure that Alt is more than or equal to 0.015% and less than or equal to 0.030% and N is less than or equal to 25ppm in the steel ladle;
an external refining process: refining the molten steel in the ladle to ensure that the nitrogen increment N is less than or equal to 10ppm, manufacturing reducing slag with fluidity, controlling argon blowing strength, and performing calcium treatment to obtain refined molten steel;
and (3) continuous casting process: pouring the refined molten steel into a tundish, purging the tundish by using argon before casting to ensure that the nitrogen increment N is less than or equal to 5ppm, removing impurities in the steel by using high-alkalinity tundish slag, and controlling the superheat degree of continuous casting to be not more than 25 ℃;
wherein 1ppm is 0.0001%.
5. The method for producing steel for wheel according to claim 4, further comprising blowing oxygen into a molten pool in the converter, wherein the blowing of oxygen is stopped when the amount of carbon contained in the molten pool reaches a steel-tapping requirement, and high manganese and ferrosilicon are added before the steel-tapping.
6. The method for producing a steel for wheel according to claim 4, wherein the external refining step employs an LF + RH dual-path step, wherein the LF path is heated by an electrode to perform desulfurization and temperature adjustment, and the RH path is used for degassing and decarburization;
wherein, the LF route adopts active lime and fluorite to manufacture reducing slag with fluidity.
7. The method for producing the steel for wheel according to claim 4, wherein the heating temperature in the heating furnace is 1200 ℃ to 1270 ℃, the heating time is 2.5 hours, and the holding time is 30 minutes.
8. The preparation method of the steel for wheel according to claim 4, wherein the hot continuous rolling process comprises rough rolling and finish rolling, the initial rolling temperature of the rough rolling is not lower than 1080 ℃, and the finish rolling temperature of the finish rolling is 820 ℃ to 900 ℃.
9. The method for producing a steel for wheel use according to claim 4, wherein the coiling temperature at the time of coiling is 450 to 550 ℃.
10. The method for producing a steel for wheel according to claim 4, wherein the controlled cooling is performed by means of block cooling.
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