CN114405996A - CSP flow low-carbon steel plate and manufacturing method thereof - Google Patents
CSP flow low-carbon steel plate and manufacturing method thereof Download PDFInfo
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- CN114405996A CN114405996A CN202210099802.7A CN202210099802A CN114405996A CN 114405996 A CN114405996 A CN 114405996A CN 202210099802 A CN202210099802 A CN 202210099802A CN 114405996 A CN114405996 A CN 114405996A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
- B21B45/08—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing hydraulically
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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
- B21B1/22—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 plates, strips, bands or sheets of indefinite length
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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
- B21B37/28—Control of flatness or profile during rolling of strip, sheets or plates
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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
- B21B37/46—Roll speed or drive motor control
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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
- B21B37/56—Elongation control
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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
- 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
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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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
- 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
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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
- C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
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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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- 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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- 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
- B21B1/22—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 plates, strips, bands or sheets of indefinite length
- B21B2001/225—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 plates, strips, bands or sheets of indefinite length by hot-rolling
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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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- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
Abstract
The invention provides a CSP flow low-carbon steel plate and a manufacturing method thereof, emphasizes ferrite grain coarsening in the rolling and cooling processes, reduces pearlite segregation in grain boundaries and controls the content of residual elements to improve the material strength, realizes ferrite grain coarsening, reduces the effect of pearlite segregation in grain boundaries on grain boundary strengthening, softens the material strength and reduces the yield ratio, the grain size coarsening is 2.5-3 grade, the volume of intragranular pearlite accounts for 40-45 percent, the volume of grain boundary pearlite accounts for 55-60 percent, the yield strength is reduced by 21.5-33.9 percent, the tensile strength is reduced by 7.0-16.5 percent, the yield ratio is reduced by 15.6-21.0 percent, and the elongation is equivalent; the problem that the low-carbon steel in the CSP process has high strength and yield ratio is solved, the forming performance and the hot rolling yield of the material are improved, and the production cost is reduced; the subsequent cold rolling pressure is obviously reduced, the production of the ultra-thin cold-rolled strip steel is realized, and the added value of the product is improved.
Description
Technical Field
The invention belongs to the technical field of production processes of sheet billet continuous casting and rolling steel, and particularly relates to a low-carbon steel plate in a CSP (cast steel plate) process and a manufacturing method thereof.
Background
The continuous casting and rolling technology for thin slabs is a hot rolled coil production technology developed at the end of the 80 th century, has the advantages of high production efficiency, short flow, few procedures, compact arrangement of process equipment, less occupied land, less investment, low energy consumption and the like, and is rapidly developed in the beginning of the last 21 st century of the 20 th century.
The CSP is used as an important type production line for continuous casting and rolling of thin slabs, the low-carbon steel cold-rolled base material is produced in batches by the CSP line at home and abroad at present, and the CSP has obvious advantages in the aspects of dimensional precision, thin specification rolling, plate shape control and the like. However, due to the characteristics of the CSP process, compared with the traditional hot continuous rolling process, the problems of fine structure, high strength and yield ratio and high strength and yield ratio of the hot-rolled low-carbon steel plate become one of the key problems restricting the CSP line high-quality cold-rolled base material. In order to solve the problem of high strength and yield ratio of low-carbon steel in the CSP process, the boron microalloying is mainly adopted at home and abroad, for example, the patent publication number is CN 101775557B; increasing RH procedure to reduce C content; ③ ferrite rolling process, such as CN106191681B, CN106244921B, etc. The above technique has the following problems: although boron microalloying can reduce the strength of a cold-rolled base material to a certain extent, the probability of occurrence of corner cracks of a casting blank is increased, particularly for a CSP production line, the casting blank cannot be subjected to off-line cleaning after the corner cracks occur, the stability and the smoothness of a field process are not facilitated, and the edge quality of a product is influenced. The reduction of the C content by increasing the RH process achieves the aim of reducing the strength of the cold-rolled base stock, but increases the production cost of the product by at least 40 yuan/ton.
As a new process capable of reducing the material strength, the current research results of ferrite rolling process technology at home and abroad show that the ferrite rolling process is only suitable for ultra-low carbon steel (C is less than or equal to 0.040%) and IF steel (C is less than 0.005%), and the stability of the low-carbon steel rolling process with C being more than 0.040% is difficult to ensure. The low-carbon steel in the CSP process at present basically adopts an LF furnace refining process, the actual control range of the C content is 0.035-0.070%, and the C content cannot be stably controlled to be less than or equal to 0.040%, so that the ferrite rolling process is not suitable for rolling the low-carbon steel in the CSP process at present.
In summary, the existing three measures of reducing the strength of the CSP low-carbon steel mainly include boron microalloying, increasing the RH process to reduce the C content and ferrite rolling, and the measures can increase the production cost or are not favorable for the smooth operation of the field process or are not suitable.
At present, no prior art can effectively reduce the strength and the yield ratio of low-carbon steel in the CSP process, reduce the production cost and improve the yield.
Disclosure of Invention
The invention aims to provide a CSP flow low-carbon steel plate and a manufacturing method thereof, which can solve the problems of high strength and yield ratio of the CSP flow low-carbon steel on the one hand and is beneficial to improving the forming performance by reasonable smelting, continuous casting, heating, rolling, cooling and coiling processes; on the other hand, the hot rolling yield can be improved, and the production cost can be reduced; moreover, the pressure of subsequent cold rolling can be obviously reduced, the production of the ultra-thin cold-rolled strip steel is facilitated, and the added value of products is improved.
The invention has the following specific technical scheme
A low-carbon steel plate in a CSP process comprises the following components in percentage by mass:
c: 0.035-0.070%; si: less than or equal to 0.050 percent; mn: less than or equal to 0.30 percent; p: less than or equal to 0.015 percent; s: less than or equal to 0.010 percent; and Als: 0.020-0.060%, and the balance of Cr + Mo + Ni + Cu is less than or equal to 0.040%, and the balance of Fe and inevitable impurities.
The CSP flow low-carbon steel plate has a metallographic structure comprising ferrite and a small amount of pearlite, wherein the volume ratio of the ferrite is 96.5-97.5%, and the volume ratio of the pearlite is 2.5-3.5%; the grain size of ferrite is 6.5-8.0 grade, pearlite is distributed in ferrite crystal except in ferrite crystal boundary, the volume of pearlite in crystal accounts for 40-45%, and the volume of pearlite in crystal boundary accounts for 55-60%.
The low-carbon steel plate in the CSP process has the yield strength of 195-219 MPa, the tensile strength of 324-347 MPa, the yield ratio of not more than 0.63 and the elongation of 38.0-40.0%.
In the invention, on the aspect of microstructure design, the target microstructure is coarse ferrite and a small amount of pearlite and coarse ferrite structure, so that on one hand, the contribution of fine-grain reinforcement to the strength of the material can be obviously reduced; on the other hand, the coarse grains can obviously reduce the yield ratio of the material, and are beneficial to improving the forming performance of the material. Meanwhile, the precipitation position of pearlite is changed, the precipitation quantity of the pearlite at the grain boundary position of ferrite is reduced, a part of pearlite is precipitated in ferrite grains, the contribution of the pearlite to the grain boundary strengthening effect is reduced, and the strength of the material is further favorably reduced, wherein the volume ratio of the pearlite in the grains is 40-45%, and the volume ratio of the pearlite at the grain boundary is 55-60%.
In the aspect of chemical composition design, the invention limits the contents of Cr, Mo, Ni and Cu in the residual alloy elements besides limiting C, Si, Mn, P, S and Als, wherein the contents of Cr + Mo + Ni + Cu are less than or equal to 0.040 percent, and the invention mainly aims to control the solid solution strengthening and precipitation strengthening effects of the residual elements and reduce the effect of the residual elements on improving the material strength.
The invention provides a manufacturing method of a low-carbon steel plate in a CSP process, which comprises the processes of converter smelting, LF furnace refining, thin slab continuous casting, heating, rolling, cooling and coiling; the control is as follows:
according to the components, converter smelting and LF furnace refining are carried out, self-circulation scrap steel is used, scrap steel with high Cr, Ni, Cu and Mo contents is not used, and tapping slag blocking is enhanced.
The thin slab continuous casting specifically comprises the following steps: the thickness of the continuous casting blank is 60-65 mm, and the charging temperature of the casting blank is controlled to be 950-1000 ℃;
the heating is specifically as follows: heating the casting blank in a roller hearth type heating furnace, keeping the temperature for 20-30 min, controlling the discharging temperature of the casting blank to be 1000-1050 ℃, and controlling the air surplus coefficient to be 0.95-1.10;
according to the invention, in terms of the heating process design, the discharging temperature of the casting blank is 1000-1050 ℃, and the excess air coefficient is 0.95-1.10, so that the purpose of reducing the surface oxidation burning loss of the casting blank on one hand, and preventing the excessive heating temperature from causing the hard removal of the iron scale on the surface of the casting blank is achieved; on the other hand, under certain conditions such as rolling load distribution, inter-stand cooling water, finish rolling temperature and the like, the tapping temperature is reduced, the casting blank finish rolling inlet temperature can be reduced, the rolling speed can be increased, and the production efficiency can be improved.
The rolling is specifically as follows: after descaling by high-pressure water, rolling in a 7-stand finishing mill set, wherein the initial rolling temperature is 950-1000 ℃, and the final rolling temperature is controlled to be 780-830 ℃;
furthermore, in the rolling process, the cumulative reduction rate of the F1-F3 stands is not less than 85 percent, the reduction rate of the F4 stands is not more than 10 percent, and the cumulative reduction rate of the F5-F7 stands is not less than 50 percent; F3-F5 finish rolling machine frame is put into use, the mass concentration of the oil-water mixed liquid is 0.3-0.4%, and the injection pressure is 0.4-0.6 MPa;
in the design of the rolling process, the frames F1-F3 are rolled at a high reduction ratio, the characteristic of high temperature and high reduction of the rolled piece is fully exerted, the temperature of the rolled piece of the frame F4 is in a two-phase region of transformation from an austenite phase to a ferrite phase, the rolling stability and the quality control of plate shape are not facilitated when the rolling reduction ratio is too large or too small, the rolling reduction ratio is not more than 10 percent, the rolling reduction ratio of the frame F4 is not more than 10 percent, the frames F5-F7 are in a ferrite phase transformation temperature region, the ferrite crystal grains are difficult to dynamically recrystallize, and in order to ensure the coarsening effect of the ferrite crystal grains and fully coarsening the ferrite crystal grains, the accumulated reduction ratio in the ferrite phase transformation region is not less than 50 percent. The lubricating rolling process is used for the finish rolling stands of F3-F5, and mainly aims to reduce rolling pressure and improve the stability of the transition rolling process of a two-phase region and the surface quality of a product. The finishing rolling temperature is controlled to be 780-830 ℃, so that on one hand, the proportion of ferrite dynamic recrystallization can be controlled, and the grain size of ferrite is coarsened; on the other hand, the temperature area is in a ferrite phase change area, the deformation resistance of the rolled piece is small, the influence of the temperature on the deformation resistance is small, and the stability and the shape of the rolled piece in the rolling process are improved.
The cooling specifically comprises the following steps: and (3) adopting a sectional cooling mode for the steel plate after final rolling, slowly cooling the steel plate at the speed of 5-10 ℃/s in the first section, cooling the steel plate for 6-8 s, then cooling the steel plate at the speed of 20-30 ℃/s in the second section, cooling the steel plate to 680-730 ℃, coiling, and air cooling the steel plate to room temperature after coiling.
According to the invention, on the aspect of cooling process design, a sectional cooling mode is adopted, the slow cooling is carried out at the speed of 5-10 ℃/s, the supercooling degree and the ferrite nucleation rate can be reduced by the slow cooling after rolling, and the ferrite can be recovered or completely statically recrystallized by matching with the high coiling temperature of 680-730 ℃, so that ferrite grains can be rapidly and fully grown.
The low-carbon steel plate produced by the method has a metallographic structure comprising ferrite and a small amount of pearlite, wherein the volume ratio of the ferrite is 96.5-97.5%, and the volume ratio of the pearlite is 2.5-3.5%; the grain size of ferrite is 6.5-8.0 grade, pearlite is distributed in ferrite crystal except in ferrite crystal boundary, the volume percentage of the pearlite distributed in the ferrite crystal is 40-45%, the volume percentage of the pearlite distributed in the ferrite crystal boundary is 55-60%. The product has yield strength of 195-219 MPa, tensile strength of 324-347 MPa, yield ratio of less than or equal to 0.63 and elongation of 38.0-40.0%. Meanwhile, when a 4-stand cold continuous rolling unit is adopted for rolling, the reduction range of the cold rolling pressure is up to 27.17 percent, thereby being beneficial to rolling of the cold-rolled strip steel with the extremely-thin specification and improving the added value of products.
The metallographic structure of the low-carbon steel plate produced by the CSP conventional process in the prior art is ferrite and a small amount of pearlite, the volume ratio of the ferrite is 96.5-97.5%, the volume ratio of the pearlite is 2.5-3.5%, the grain size of the ferrite is 9.5-10.5 grade, 100% of the pearlite is distributed in a ferrite grain boundary, the yield strength of the product is 279-295 MPa, the tensile strength is 373-388 MPa, the yield ratio is 0.75-0.77, and the elongation is 37.0-39.0%. The CSP low-carbon steel plate produced by the method has a metallographic structure comprising ferrite and a small amount of pearlite, the grain size of the ferrite is 6.5-8.0 grade, the volume ratio of the ferrite is 96.5-97.5%, the volume ratio of the pearlite is 2.5-3.5%, the pearlite is distributed in the ferrite crystal except for the ferrite crystal boundary, the volume ratio of the pearlite in the crystal is 40-45%, and the volume ratio of the crystal boundary pearlite is 55-60%. The product has yield strength of 195-219 MPa, tensile strength of 324-347 MPa, yield ratio of less than or equal to 0.63 and elongation of 38.0-40.0%.
Therefore, compared with the CSP conventional process, the CSP low-carbon steel plate produced by the method realizes the effects of ferrite grain coarsening and pearlite segregation reduction on grain boundary strengthening, and realizes the effects of softening the material strength and reducing the yield ratio, the grain size coarsening is 2.5-3 grades, the volume ratio of the pearlite in the grain is 40-45%, the volume ratio of the pearlite in the grain boundary is 55-60%, the yield strength is reduced by 21.5-33.9%, the tensile strength is reduced by 7.0-16.5%, the yield ratio is reduced by 15.6-21.0%, and the elongation is equivalent.
In addition, the invention adopts the processes of low-temperature heating and low-temperature rolling, on one hand, the gas consumption of the heating furnace can be effectively reduced by 0.22GJ/t material, and the energy consumption cost of the heating furnace is reduced by about 8 yuan/t material; on the other hand, the oxidation burning loss of the casting blank can be effectively reduced, and the hot rolling yield is improved by about 0.21%; moreover, on the premise of ensuring the mechanical property of the final cold-rolled annealed product, the cold-rolling pressure can be obviously reduced, and the reduction range of the cold-rolling pressure is as high as 27.17 percent.
Compared with the prior art, the invention realizes the effects of ferrite grain coarsening and pearlite grain boundary segregation reduction on grain boundary strengthening, and realizes material strength softening, wherein the grain size coarsening is 2.5-3 grade, the volume ratio of the pearlite in the grains accounts for 40-45%, the volume ratio of the pearlite in the grain boundaries accounts for 55-60%, the yield strength is reduced by 21.5-33.9%, the tensile strength is reduced by 7.0-16.5%, the yield ratio is reduced by 15.6-21.0%, and the elongation is equivalent; the method solves the problem of high strength and yield ratio of low-carbon steel in the CSP process, reduces the production cost and the subsequent cold rolling pressure on the premise of ensuring the mechanical property of the final cold rolling annealed product, is particularly suitable for rolling cold-rolled strip steel with an extremely thin specification, and is beneficial to improving the added value of products.
Drawings
FIG. 1 shows a metallographic structure of low carbon steel according to example 1 of the present invention;
FIG. 2 is a metallographic structure of low carbon steel according to example 2 of the present invention;
FIG. 3 is a metallographic structure of low carbon steel according to example 3 of the present invention;
FIG. 4 shows a metallographic structure of low carbon steel corresponding to comparative example 1;
FIG. 5 shows a metallographic structure of low carbon steel corresponding to comparative example 2;
FIG. 6 shows a metallographic structure of low carbon steel corresponding to comparative example 3;
FIG. 7 is a distribution of pearlite in a low carbon steel structure according to example 1 of the present invention;
FIG. 8 is a distribution of pearlite in a low carbon steel structure according to example 2 of the present invention;
FIG. 9 shows distribution of pearlite in a low carbon steel structure according to example 3 of the present invention;
FIG. 10 is a pearlite distribution in a low carbon steel structure corresponding to comparative example 1;
FIG. 11 is a pearlite distribution in a low carbon steel structure corresponding to comparative example 2;
FIG. 12 is a pearlite distribution in a low carbon steel structure corresponding to comparative example 3;
FIG. 13 is a comparison of cold rolling pressures of the present invention 1 to 3 and comparative examples 1 to 3.
Detailed Description
The technical solution of the present invention will be described below by way of specific examples.
Example 1 to example 3
A low-carbon steel plate in a CSP process comprises the following components in percentage by mass: as shown in table 1, the balance not shown in table 1 is Fe and inevitable impurities.
Comparative examples 1 to 3
A low-carbon steel plate in a CSP process comprises the following components in percentage by mass: as shown in table 1, the balance not shown in table 1 is Fe and inevitable impurities.
TABLE 1 examples and comparative examples chemical composition (mass percent, wt%)
| Numbering | C | Si | Mn | P | S | Als | Cr | Mo | Ni | Cu | Cr+Mo+Ni+Cu |
| Example 1 | 0.055 | 0.023 | 0.12 | 0.012 | 0.003 | 0.028 | 0.011 | 0.002 | 0.006 | 0.009 | 0.028 |
| Example 2 | 0.039 | 0.019 | 0.11 | 0.011 | 0.002 | 0.024 | 0.013 | 0.003 | 0.005 | 0.008 | 0.029 |
| Example 3 | 0.045 | 0.025 | 0.11 | 0.009 | 0.004 | 0.031 | 0.016 | 0.002 | 0.007 | 0.008 | 0.033 |
| Comparative example 1 | 0.053 | 0.028 | 0.10 | 0.012 | 0.003 | 0.025 | 0.025 | 0.004 | 0.021 | 0.026 | 0.076 |
| Comparative example 2 | 0.035 | 0.021 | 0.12 | 0.010 | 0.003 | 0.026 | 0.028 | 0.005 | 0.023 | 0.020 | 0.076 |
| Comparative example 3 | 0.048 | 0.029 | 0.12 | 0.013 | 0.002 | 0.021 | 0.021 | 0.002 | 0.024 | 0.023 | 0.070 |
The above examples and comparative examples were produced according to the following method, converter smelting, LF furnace refining, thin slab continuous casting, heating, rolling, cooling and coiling process, specifically controlled as follows:
converter smelting and LF furnace refining are carried out according to the components, self-circulation scrap steel is used, scrap steel with high Cr, Ni, Cu and Mo contents is not used, and steel tapping and slag stopping are enhanced.
The thin slab continuous casting specifically comprises the following steps: strictly protecting and pouring, wherein the thickness of a continuous casting blank is 60-65 mm, and the temperature of the casting blank in a heating furnace is controlled to be 950-1000 ℃;
the heating is specifically as follows: heating the casting blank in a roller hearth type heating furnace, keeping the temperature for 20-30 min, controlling the discharging temperature of the casting blank to be 1000-1050 ℃, and controlling the air surplus coefficient to be 0.95-1.10;
the rolling is specifically as follows: after descaling by high-pressure water, rolling in a 7-stand finishing mill set, wherein the initial rolling temperature is 950-1000 ℃, and the final rolling temperature is controlled to be 780-830 ℃;
furthermore, in the rolling process, the cumulative reduction rate of the F1-F3 stands is not less than 85 percent, the reduction rate of the F4 stands is not more than 10 percent, and the cumulative reduction rate of the F5-F7 stands is not less than 50 percent; F3-F5 finish rolling machine frame is put into use, the mass concentration of the oil-water mixed liquid is 0.3-0.4%, and the injection pressure is 0.4-0.6 MPa;
the cooling specifically comprises the following steps: and (3) adopting a sectional cooling mode for the steel plate after final rolling, slowly cooling the steel plate at the speed of 5-10 ℃/s for 6-8 s, cooling the steel plate at the speed of 20-30 ℃/s to 680-730 ℃ for coiling, and air cooling the steel plate to room temperature after coiling.
The hot rolling process specific parameters of each example and comparative example are shown in tables 2 and 3, the properties of the steel are shown in table 4, and the cold rolling parameters are shown in tables 5 and 6.
TABLE 2 Hot Rolling temperature parameters of examples and comparative examples
TABLE 3 examples and comparative examples Hot Rolling F1-F7 Rack reduction, lubricated Rolling Process parameters
TABLE 4 organization and mechanical properties of examples and comparative examples
TABLE 5 Cold Rolling reduction of examples and comparative examples
TABLE 6 Rolling pressure for cold rolling of examples and comparative examples
Note that the pressure drops in the tables are for example 1 versus comparative example 1, example 2 versus comparative example 2, example 3 versus comparative example 3.
The metallographic structures corresponding to the invention and the conventional process are respectively shown in fig. 1-6, the pearlite distribution corresponding to the invention 1-3 and the conventional process is respectively shown in fig. 7-12, and the cold rolling pressure corresponding to the invention and the conventional process is shown in fig. 13. The low-carbon steel produced by the method has a metallographic structure of ferrite and a small amount of pearlite, the grain size of the ferrite is 6.5-8.0 grade, the pearlite is distributed in the ferrite except for the ferrite grain boundary, the volume of the pearlite in the ferrite grain is 40-45%, and the volume of the grain boundary pearlite is 55-60%. The metallographic structure of the low-carbon steel produced by the CSP conventional process is ferrite and a small amount of pearlite, the grain size of the ferrite is 9.5-10.5 grades, and 100% of the pearlite is distributed at the grain boundary position of the ferrite. Compared with the CSP conventional process, the invention emphasizes the control strategy of ferrite grain coarsening and pearlite segregation reduction in the grain boundary during rolling and cooling, realizes the effect of ferrite grain coarsening and pearlite segregation reduction on grain boundary strengthening, and realizes the material strength softening, yield ratio reduction and strength softening, the grain size coarsening is 2.5-3 grade, the volume ratio of the pearlite in the crystal is 40-45%, the volume ratio of the pearlite in the grain boundary is 55-60%, the yield strength is reduced by 21.5-33.9%, the tensile strength is reduced by 7.0-16.5%, the yield ratio is reduced by 15.6-21.0%, and the elongation is equivalent. In addition, the invention adopts the processes of low-temperature heating and low-temperature rolling, on one hand, the gas consumption of the heating furnace can be effectively reduced by 0.22GJ/t material, and the energy consumption cost of the heating furnace is reduced by about 8 yuan/t material; on the other hand, the oxidation burning loss of the casting blank can be effectively reduced, and the hot rolling yield is improved by about 0.21%; moreover, the cold rolling pressure can be obviously reduced, the reduction range of the cold rolling pressure reaches 27.17 percent, and the method is particularly suitable for rolling cold-rolled strip steel with an extremely thin specification and is beneficial to improving the added value of products.
Claims (10)
1. The CSP process low-carbon steel plate is characterized in that a metallographic structure of the CSP process low-carbon steel plate is ferrite and pearlite, the volume ratio of the ferrite is 96.5-97.5%, and the volume ratio of the pearlite is 2.5-3.5%; the grain size of ferrite is 6.5-8.0 grade.
2. The CSP process low carbon steel sheet according to claim 1, wherein the microstructure of the CSP process low carbon steel sheet has pearlite distributed in ferrite crystal grains in addition to the ferrite grain boundaries, and the volume of pearlite in the grains accounts for 40-45% and the volume of pearlite in the grain boundaries accounts for 55-60%.
3. The CSP process low carbon steel plate as claimed in claim 1 or 2, wherein the CSP process low carbon steel plate has a yield strength of 195-219 MPa, a tensile strength of 324-347 MPa, a yield ratio of 0.63 or less and an elongation of 38.0-40.0%.
4. The CSP process low carbon steel plate as claimed in any one of claims 1 to 3, comprising the following components by mass percent:
c: 0.035-0.070%; si: less than or equal to 0.050 percent; mn: less than or equal to 0.30 percent; p: less than or equal to 0.015 percent; s: less than or equal to 0.010 percent; and Als: 0.020-0.060%, and the balance of Cr + Mo + Ni + Cu is less than or equal to 0.040%, and the balance of Fe and inevitable impurities.
5. A manufacturing method of the low carbon steel plate in the CSP process according to any one of claims 1 to 4, characterized in that the manufacturing method comprises converter smelting, LF furnace refining, thin slab continuous casting, heating, rolling, cooling and coiling.
6. The manufacturing method according to claim 5, characterized in that said thin slab continuous casting is in particular: the thickness of the continuous casting blank is 60-65 mm, and the temperature of the casting blank in a heating furnace is controlled to be 950-1000 ℃.
7. The manufacturing method according to claim 5, wherein the heating is specifically: the heat preservation time is 20-30 min, the discharging temperature of the casting blank is controlled to be 1000-1050 ℃, and the air surplus coefficient is 0.95-1.10.
8. The manufacturing method according to claim 5, characterized in that the rolling is in particular: and (3) descaling by high-pressure water, and then rolling in a 7-stand finishing mill set, wherein the initial rolling temperature is 950-1000 ℃, and the final rolling temperature is controlled at 780-830 ℃.
9. The manufacturing method according to claim 8, wherein the cumulative reduction ratio of the F1-F3 stands is not less than 85%, the reduction ratio of the F4 stands is not more than 10%, and the cumulative reduction ratio of the F5-F7 stands is not less than 50% during rolling; the lubricating rolling process is used for the F3-F5 finishing mill frame, the mass concentration of the oil-water mixed liquid is 0.3-0.4%, and the injection pressure is 0.4-0.6 MPa.
10. The manufacturing method according to claim 5, characterized in that the cooling is in particular: and (3) adopting a sectional cooling mode for the steel plate after final rolling, slowly cooling the steel plate at the speed of 5-10 ℃/s for 6-8 s, cooling the steel plate at the speed of 20-30 ℃/s to 680-730 ℃ for coiling, and air cooling the steel plate to room temperature after coiling.
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| CN202210099844.0A Active CN114192577B (en) | 2021-10-29 | 2022-01-27 | Method suitable for rolling ultrathin cold-rolled strip steel by CSP cold-rolled base material |
| CN202210099700.5A Active CN114226453B (en) | 2021-10-29 | 2022-01-27 | Manufacturing method for low-carbon steel and improving performance uniformity of ferrite-rolled low-carbon steel |
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Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1927485A (en) * | 2006-09-29 | 2007-03-14 | 邯郸钢铁股份有限公司 | Technique for CSP sheet billet production line cold rolling feeding |
| CN102703808A (en) * | 2012-06-12 | 2012-10-03 | 武汉钢铁(集团)公司 | Steel for 300MPa-grade automobile structural part and production method for steel |
| JP2016169403A (en) * | 2015-03-11 | 2016-09-23 | Ｊｆｅスチール株式会社 | Low yield ratio high strength thick steel plate for building structure excellent in toughness at super high heat-input heat affected zone and production method therefor |
| CN108611563A (en) * | 2018-05-09 | 2018-10-02 | 马钢(集团)控股有限公司 | A kind of CSP flows excellent formability energy mild steel steel plate and its manufacturing method |
| CN108994081A (en) * | 2018-06-25 | 2018-12-14 | 中冶赛迪工程技术股份有限公司 | A method of mild steel being produced using ferrite rolling in ESP production line |
| CN110578095A (en) * | 2019-10-22 | 2019-12-17 | 马鞍山钢铁股份有限公司 | 1200 MPa-level hot-rolled ultrahigh-strength steel plate and manufacturing method thereof |
| CN111229827A (en) * | 2020-03-02 | 2020-06-05 | 马鞍山钢铁股份有限公司 | Hot-rolled H-shaped steel with yield strength of 450MPa and production method thereof |
| CN113234994A (en) * | 2021-04-14 | 2021-08-10 | 马鞍山钢铁股份有限公司 | Hot-rolled high-strength weather-resistant steel plate with yield strength of 600MPa and production method thereof |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19531538A1 (en) * | 1995-08-25 | 1997-02-27 | Schloemann Siemag Ag | Hot strip production plant for ferritic rolling and method for producing ferritic rolled strip |
| JP2005169454A (en) * | 2003-12-11 | 2005-06-30 | Jfe Steel Kk | Steel strip manufacturing equipment and method |
| CN101230436A (en) * | 2008-02-26 | 2008-07-30 | 山东泰山钢铁集团有限公司 | Common low-carbon low-silicon hot-rolling steel belt and method for manufacturing same |
| CN101906571B (en) * | 2010-06-24 | 2012-07-25 | 武汉钢铁(集团)公司 | CSP process-based manufacturing method of economical hot-rolled dual-phase steel with high surface quality |
| CN102943200B (en) * | 2012-11-09 | 2015-01-07 | 武汉钢铁(集团)公司 | Method for producing low-carbon thin pickling steel with yield ratio less than or equal to 0.8 through CSP (cast steel plate) process |
| CN106077090B (en) * | 2016-06-06 | 2018-09-04 | 日照宝华新材料有限公司 | The method for producing Thin Specs checkered steel plate based on ESP bar strip continuous casting and rolling flow paths |
| CN106191681B (en) * | 2016-08-30 | 2018-03-27 | 日照钢铁控股集团有限公司 | The ferritic method of mild steel is produced based on ESP bar strip continuous casting and rolling flow paths |
| CN106244921B (en) * | 2016-08-30 | 2018-05-01 | 武汉钢铁有限公司 | A kind of method in CSP producing lines using rolling in ferrite domains production mild steel |
| JP2019034325A (en) * | 2017-08-21 | 2019-03-07 | Ｊｆｅスチール株式会社 | Method for manufacturing ferritic stainless cold-rolled steel strip |
| CN107641699B (en) * | 2017-09-20 | 2019-06-18 | 武汉钢铁有限公司 | Method based on CSP process production thin gauge hot rolling DP780 steel |
| CN207288354U (en) * | 2017-10-16 | 2018-05-01 | 北京科技大学 | Ultra-low carbon coil of strip ferrite rolling device is used in endless casting rolling production ultra-deep punching |
| CN110665965A (en) * | 2019-10-17 | 2020-01-10 | 山东钢铁集团日照有限公司 | Stable production method of hot-rolled extreme thin cold-rolled base material |
| CN111633028B (en) * | 2020-05-15 | 2021-09-10 | 武汉钢铁有限公司 | Production method for producing thin-specification low-carbon steel by ferrite rolling on CSP production line |
-
2021
- 2021-10-29 CN CN202111273680.0A patent/CN113996651A/en not_active Withdrawn
-
2022
- 2022-01-27 CN CN202210099844.0A patent/CN114192577B/en active Active
- 2022-01-27 CN CN202210099700.5A patent/CN114226453B/en active Active
- 2022-01-27 CN CN202210099802.7A patent/CN114405996B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1927485A (en) * | 2006-09-29 | 2007-03-14 | 邯郸钢铁股份有限公司 | Technique for CSP sheet billet production line cold rolling feeding |
| CN102703808A (en) * | 2012-06-12 | 2012-10-03 | 武汉钢铁(集团)公司 | Steel for 300MPa-grade automobile structural part and production method for steel |
| JP2016169403A (en) * | 2015-03-11 | 2016-09-23 | Ｊｆｅスチール株式会社 | Low yield ratio high strength thick steel plate for building structure excellent in toughness at super high heat-input heat affected zone and production method therefor |
| CN108611563A (en) * | 2018-05-09 | 2018-10-02 | 马钢(集团)控股有限公司 | A kind of CSP flows excellent formability energy mild steel steel plate and its manufacturing method |
| CN108994081A (en) * | 2018-06-25 | 2018-12-14 | 中冶赛迪工程技术股份有限公司 | A method of mild steel being produced using ferrite rolling in ESP production line |
| CN110578095A (en) * | 2019-10-22 | 2019-12-17 | 马鞍山钢铁股份有限公司 | 1200 MPa-level hot-rolled ultrahigh-strength steel plate and manufacturing method thereof |
| CN111229827A (en) * | 2020-03-02 | 2020-06-05 | 马鞍山钢铁股份有限公司 | Hot-rolled H-shaped steel with yield strength of 450MPa and production method thereof |
| CN113234994A (en) * | 2021-04-14 | 2021-08-10 | 马鞍山钢铁股份有限公司 | Hot-rolled high-strength weather-resistant steel plate with yield strength of 600MPa and production method thereof |
Non-Patent Citations (2)
| Title |
|---|
| 张中东;许兴;胡学文;: "新型低C-Mn双相钢变形及非变形过冷奥氏体连续转变", 上海金属, no. 03, pages 21 - 25 * |
| 谭佳梅;陈良;周学俊;张超;高智;: "武钢CSP低碳冷轧基料铁素体轧制工艺开发与实践", 武钢技术, no. 04, pages 25 - 28 * |
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| CN114192577A (en) | 2022-03-18 |
| CN113996651A (en) | 2022-02-01 |
| CN114226453A (en) | 2022-03-25 |
| CN114192577B (en) | 2023-07-25 |
| CN114226453B (en) | 2023-04-28 |
| CN114405996B (en) | 2023-08-29 |
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