CN115488166A - Method for rapidly determining difference of cooling speed of steel plate - Google Patents
Method for rapidly determining difference of cooling speed of steel plate Download PDFInfo
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- CN115488166A CN115488166A CN202210978625.XA CN202210978625A CN115488166A CN 115488166 A CN115488166 A CN 115488166A CN 202210978625 A CN202210978625 A CN 202210978625A CN 115488166 A CN115488166 A CN 115488166A
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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
- B21B45/02—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 lubricating, cooling, or cleaning
- B21B45/0203—Cooling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
- B21B38/02—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product for measuring flatness or profile of strips
Abstract
The application discloses a method for rapidly determining difference of cooling speed of steel plates, which comprises the following steps: s1, carrying out hot rolling on a steel plate blank, wherein the thickness of the steel plate blank is more than 12mm, preferably more than 15 mm; s2, cooling the hot-rolled steel plate blank, wherein the cooling comprises laminar flow cooling; s3, carrying out real-time flatness detection on the cooled steel plate blank to obtain a flatness detection result after the steel plate blank is cooled, wherein the flatness detection result comprises the shape of the cooled steel plate blank; and S4, determining the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank according to the detection result of the flatness after cooling. The method solves the problems that in the prior art, judgment can be carried out only after sampling and structural performance analysis, the method has real-time performance, can quickly determine the difference of the cooling speed of the steel plate, and can be adjusted in time in the production process; can discover and save large batch of steel plate blanks in time, improve the efficiency and reduce the waste.
Description
Technical Field
The application belongs to the technical field of steel cooling, and particularly relates to a method for rapidly determining cooling speed difference of a steel plate.
Background
In the hot rolling production process of the steel plate, the steel plate is cooled after being discharged out of an F7 rolling mill frame, which is a conventional process. For steel plates with thickness of more than 12mm, the performance in the thickness direction is not uniform and the plate shape is poor, which is a big difficulty faced at present. In order to ensure that the steel sheet has the same properties in the thickness direction and good sheet shape, the cooling rates of the upper and lower surfaces of the steel sheet are required to be the same. When the steel plate is cooled by the upper and lower cooling headers, the cooling rates of the upper and lower surfaces of the steel plate cannot be made uniform if only the same water flow rate, ratio and pressure are applied to the upper and lower cooling headers. The respective speeds of the upper and lower cooling headers can only be set empirically for different steel grades, so that the cooling speeds of the upper and lower surfaces of the steel sheet are as equal as possible.
In the prior art, the cooled thick plate blank is sampled, the structure performance of the thick plate blank is analyzed, the cooling technological parameters are adjusted according to the performance difference, the period of sampling and adjusting is as long as 4-7 days, and meanwhile, countless steel plates are cooled by adopting the same cooling technological parameters. The method for sampling and analyzing the steel plate blank has serious hysteresis, influences the performance of the steel plate in batches, and cannot find and save the steel plate in time.
Disclosure of Invention
In view of this, the present application provides a method for quickly determining a difference in cooling speed of a steel plate, which solves the problem that the cooling speed of the steel plate cannot be determined in time in the prior art.
In a first aspect, embodiments of the present application provide a method for quickly determining a difference in cooling rates of steel plates, including the following steps:
s1, hot rolling a steel plate blank, wherein the thickness of the steel plate blank is more than 12mm, preferably more than 15 mm;
s2, cooling the hot-rolled steel plate blank, wherein the cooling comprises laminar flow cooling;
s3, performing real-time flatness detection on the cooled steel plate blank to obtain a cooled flatness detection result of the steel plate blank, wherein the cooled flatness detection result comprises the plate shape of the cooled steel plate blank;
and S4, determining the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank according to the detection result of the flatness after cooling.
According to an embodiment of one aspect of the application, the cooling further comprises ultra-fast cooling, the ultra-fast cooling being performed before the laminar cooling.
According to an embodiment of an aspect of the present application, the S1 step further includes: and performing flatness detection on the hot-rolled steel plate blank to obtain an initial flatness detection result, wherein the initial flatness detection result comprises the shape of the hot-rolled steel plate blank.
According to an embodiment of an aspect of the present application, the step S4 specifically includes: and correcting the cooled flatness detection result by using the initial flatness detection result to obtain the plate shape of the steel plate blank caused by thermal expansion, and determining the difference of the cooling speed of the upper surface and the lower surface of the steel plate blank according to the corrected cooled flatness detection result.
According to an embodiment of an aspect of the present application, the step S2 specifically includes: cooling the hot rolled steel plate slab to cool the steel plate slab to 560 ℃ to 600 ℃, wherein the cooling comprises laminar cooling.
According to an embodiment of an aspect of the application, the method further comprises:
and S5, adjusting the cooling parameters according to the difference of the cooling speed of the upper surface and the lower surface of the steel plate blank so as to reduce the difference of the cooling speed of the upper surface and the lower surface, wherein the cooling parameters comprise at least one of pressure, water flow speed and water flow rate of the upper cooling header and the lower cooling header respectively and the water flow rate ratio of the upper cooling header and the lower cooling header.
According to an embodiment of one aspect of the present application, the cooling parameter is a water flow ratio of the upper cooling header and the lower cooling header.
In a second aspect, embodiments of the present application provide a system for rapidly determining a cooling rate of a steel plate, the system including:
the hot rolling unit is used for hot rolling the steel plate blank;
the cooling device is used for cooling the hot-rolled steel plate blank, and comprises a laminar flow cooling device;
the flatness detection device is used for carrying out real-time flatness detection on the cooled steel plate blank to obtain a cooled flatness detection result of the steel plate blank, wherein the cooled flatness detection result comprises the plate shape of the cooled steel plate blank;
and the cooling speed determining device is used for determining the difference of the cooling speed of the upper surface and the lower surface of the steel plate blank in the cooling equipment according to the flatness detection result.
According to an embodiment of one aspect of the application, the system further comprises:
and the cooling parameter adjusting device is used for adjusting the cooling parameters of the cooling equipment according to the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank so as to reduce the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank.
According to an embodiment of an aspect of the present application, the flatness detecting apparatus further includes a flatness detector disposed at a distal end of the hot rolling mill group, for performing flatness detection on a hot-rolled steel plate slab to obtain an initial flatness detection result;
and the cooling speed determining device is used for correcting the cooled flatness detection result by using the initial flatness detection result so as to obtain the plate shape of the steel plate blank caused by thermal expansion, and determining the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank according to the corrected cooled flatness detection result.
Compared with the prior art, the application has at least the following beneficial effects:
according to the method, after hot rolling, the shape of the steel plate blank is obtained by performing real-time flatness detection on the steel plate blank with the thickness of more than 12mm after cooling; based on the influence of thermal expansion on the plate shape of the steel plate blank in cooling, the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank in cooling can be determined according to the plate shape of the steel plate blank, the method is timely and accurate, and the long-flow analysis method for judging whether the cooling speeds of the upper surface and the lower surface of the steel plate blank in cooling are consistent by sampling a thick hot rolled plate, analyzing the structure performance and evaluating the structure performance difference of the steel plate blank in the thickness direction in the prior art is solved; the method has the advantages that judgment after sampling and structural performance analysis in the prior art is avoided, the method has real-time performance, the cooling speed difference of the steel plates can be rapidly determined, timely adjustment is carried out in the production process, and performance unevenness of batch thick steel types in the thickness direction is avoided; can discover and save large batch of steel plate blanks in time, improve the efficiency and reduce the waste.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly described below, and for those skilled in the art, other drawings may be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic flow chart illustrating a method for rapidly determining a difference in cooling rates of steel sheets according to an embodiment of the present application;
FIG. 2 is a schematic metallographic structure of a steel material according to an embodiment of the present disclosure;
FIG. 3 is a graph of the corresponding cooling rate of the steel plate versus the plate shape for the upper and lower cooling headers in a cooling process provided by an embodiment of the present application;
FIG. 4 is a schematic diagram of a system for rapidly determining the cooling rate of a steel plate according to an embodiment of the present application;
FIG. 5 is a diagram of a cooled steel plate provided in example 1 of the present application;
FIG. 6 is a sheet form diagram of a cooled steel sheet provided in an example 2 of the present application;
FIG. 7 is a metallographic structure diagram of a steel sheet provided in example 1 of the present application;
FIG. 8 is a metallographic structure diagram of a steel sheet provided in example 2 of the present application;
FIG. 9 is a diagram of a steel plate after adjustment of cooling parameters provided by an embodiment of the present application;
FIG. 10 is a metallographic structure representation of a steel plate after adjustment of cooling parameters according to an embodiment of the present application.
The device comprises a hot rolling unit 100, a hot rolling unit 200, a cooling device 210, an ultra-fast cooling device 211, an upper cooling header 212, a lower cooling header 220, a layer cooling device 300, a flatness detection device 400, a cooling speed determination device 500, a conveying roller 600 and a coiling device.
Detailed Description
In order to make the application purpose, technical solution and beneficial technical effects of the present application clearer, the present application is further described in detail with reference to the following embodiments. It should be understood that the embodiments described in this specification are only for explaining the present application and are not intended to limit the present application.
For the sake of brevity, only some numerical ranges are explicitly disclosed herein. However, any lower limit may be combined with any upper limit to form ranges not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and similarly any upper limit may be combined with any other upper limit to form a range not explicitly recited. Also, although not explicitly recited, each point or individual value between endpoints of a range is encompassed within the range. Thus, each point or individual value can form a range not explicitly recited as its own lower or upper limit in combination with any other point or individual value or in combination with other lower or upper limits.
In the description of the present application, it is to be noted that, unless otherwise specified, "above" and "below" are inclusive of the present number, and "plural" of "one or more" means two or more.
The above summary of the present application is not intended to describe each disclosed embodiment or every implementation of the present application. The following description more particularly exemplifies illustrative embodiments. At various points throughout this application, guidance is provided through a list of embodiments that can be used in various combinations. In each instance, the list is merely a representative group and should not be construed as exhaustive.
In hot rolling production, the steel sheet is usually cooled after exiting the F7 stand for performance control purposes. The cold permeability of the thick gauge steel sheet of 12mm or more is remarkably different from that of the thin gauge steel sheet (4 mm or less): the thin-gauge steel plate is insensitive to the difference of the cooling speeds of the ultra-fast cooling/layer cooling upper and lower collecting pipes, is easy to cool completely, and has uniform cooling structure performance in the thickness direction; the thick steel plate is sensitive to the difference of the cooling speed of the ultra-fast cooling/layer cooling upper and lower collecting pipes, is not easy to be cooled thoroughly, and is easy to have uneven structure performance in the thickness direction.
At present, the process of thick steel plates by production enterprises mainly comprises the following steps: rolling, cooling, coiling and cooling. The steel plate is sampled and the structure property detection is generally carried out after the cooling process. One of the conventional methods for determining the difference between the cooling rates of the upper surface and the lower surface of a steel sheet during cooling is: sampling a thick hot rolled plate for structural performance analysis, and then evaluating structural performance difference in the thickness direction so as to judge. The abnormal tissue performance is discovered, and then the cooling parameters in cooling are adjusted, wherein the parameters comprise: the flow of the ultra-fast cooling/layer cooling upper and lower header cooling water or the number of header switches is adjusted.
The method has the advantages of large hysteresis, long period and low efficiency, and can not timely react to cooling parameters in the rolled steel plate, so that the batch reduction or waste judgment of the same batch of steel plates due to the uneven performance in the thickness direction is caused, and large economic loss is brought to enterprises. At present, a method and a basis for judging the cooling speed difference of the upper cooling header and the lower cooling header in real time in the rolling process of the thick-specification steel plate do not exist.
The inventor researches and discovers that the influence of cooling on the plate shape comprises two aspects of thermal expansion and phase change expansion. The essence of the thermal expansion is the expansion and contraction of the steel plate blank; the essence of the phase change expansion is: as the cooling rate changes, the prior austenite structure in the steel sheet slab dissolves, while other structures such as pearlite, bainite, etc. precipitate. Due to the different density of each structure, the volume change of the steel plate blank is caused by the phase change expansion. Through further research, the inventors found that: the phase change of the steel material in the cooling process is complicated due to the factors of different carbon content and alloy element content, different cooling speed, different cooling starting point problems and the like, and the typical structure of several steel materials is taken as an example in fig. 2 to illustrate the trend of phase change expansion along with the change of the structure.
As can be seen from fig. 2, during the transformation of austenite to martensite, the structure volume is increasing, and the nature of the structure is related to the transformation of the face centered cubic crystal structure (FCC) to the Body Centered Cubic (BCC) crystal structure and the solid solution of C atoms in the matrix. The volume expansion is not significant when austenite is transformed into ferrite/pearlite, and is significant when a large amount of austenite is transformed into martensite.
Furthermore, the inventors found that: the thermal expansion and the phase change expansion described above adversely affect the shape of the steel sheet slab. In the case of considering only the influence of thermal expansion, when the cooling rate of the upper header is lower than that of the lower header in the cooling apparatus, the steel plate exhibits a turtle back; when the cooling rate of the upper header is higher than that of the lower header, the steel plate is formed in a U-shape, as shown in fig. 3.
Based on the above, the inventors have conducted a great deal of research and provide a method for rapidly determining the difference in cooling speed between the upper surface and the lower surface of a steel plate, which realizes online determination of the difference in cooling speed between the upper surface and the lower surface of the steel plate during cooling through the change in the shape of the steel plate and avoids determination through offline structural analysis and performance tests.
In a first aspect of the embodiments of the present application, a method for quickly determining a difference in cooling rates of steel plates is provided, as shown in fig. 1, and includes the following steps:
s1, hot rolling a steel plate blank, wherein the thickness of the steel plate blank is more than 12mm, preferably more than 15 mm;
s2, cooling the hot-rolled steel plate blank, wherein the cooling comprises laminar flow cooling;
s3, performing real-time flatness detection on the cooled steel plate blank to obtain a cooled flatness detection result of the steel plate blank, wherein the cooled flatness detection result comprises the plate shape of the cooled steel plate blank;
and S4, determining the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank according to the detection result of the flatness after cooling.
According to the embodiment of the application, the steel plate blank is subjected to real-time flatness detection, so that the difference of the cooling speed of the steel plate can be judged in real time or the parameters in cooling can be adjusted in real time on the basis of judgment. The method for determining the cooling speed difference of the steel plate blank has the advantages of real-time performance, simplicity, rapidness and no additional cost increase.
According to the embodiment of the application, the method provided by the application analyzes the influence of rolling on the deformation of the thick-gauge steel plate blank in the same steel type of the same batch or different batches through theoretical research of the inventor, and can be ignored to a certain extent. The main reasons for causing the deformation of the plate blank are concentrated on the setting of cooling parameters in the cooling process; in the cooling process, the influence of thermal expansion and phase change expansion on the shape of the steel plate blank plays an opposite role, and under the condition of only considering the influence of thermal expansion, the difference of the cooling speed of the upper surface and the lower surface of the steel plate blank can be determined through the shape of the steel plate, so that the cooling parameters in the cooling process are adjusted on the basis. According to the embodiment of the application, the thicker the steel plate is, the more difficult the steel plate is to be cooled, the above specification is beneficial to amplifying the influence of the cooling speed difference in cooling on the plate shape, and the steel plate with the thickness specification of 12mm or more can be selected, and the preferable thickness specification is 15mm or more.
According to the embodiment of the application, the flatness detection in the step S4 is arranged after the cooling process in the step S3; after the flatness detection in the step S4, the steel sheet may be subjected to a coiling process, so that the steel sheet becomes a steel coil.
In some embodiments, when the plate shape of the cooled steel plate blank is a turtle-back shape, the cooling speed of the steel plate blank by the upper header is lower than that of the lower header in the cooling process, the cooling speed of the steel plate blank by the upper header can be increased, or the cooling speed of the steel plate blank by the lower header can be decreased, so that the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank is reduced, and the steel plate shape is controlled.
In some embodiments, when the plate shape of the cooled steel plate blank is a U shape, the cooling speed of the steel plate blank by the upper header is higher than that of the lower header in the cooling, and the cooling speed of the steel plate blank by the upper header may be reduced, or the cooling speed of the steel plate blank by the lower header may be increased to reduce the difference in the cooling speed between the upper surface and the lower surface of the steel plate blank, thereby controlling the steel plate shape. In some embodiments, coiling is performed after performing real-time flatness detection on the cooled steel plate blank, and the real-time flatness detection is arranged between cooling and coiling, so that the shape of the steel plate blank affected by cooling can be determined more timely and accurately.
In some embodiments, the cooling further comprises ultra-fast cooling, the ultra-fast cooling being performed prior to the laminar cooling.
According to the embodiment of the application, in the production process of the steel plate blank, the common cooling process comprises ultra-fast cooling and laminar cooling, and the two cooling processes can generate certain deformation influence on the steel plate.
In some embodiments, the same steel grade is selected and separately subjected to laminar cooling, or ultrafast cooling and laminar cooling are sequentially performed, so that the respective influences on the plate shape in the ultrafast cooling and the laminar cooling can be distinguished.
In some embodiments, at least two grades of steel are selected and used for respectively and independently carrying out laminar cooling, or carrying out ultrafast cooling and laminar cooling in sequence, and the influence of the upper collecting pipe and the lower collecting pipe on the cooling speed of the steel plate in the ultrafast cooling and the laminar cooling can be respectively judged.
In some embodiments, the S1 step further comprises: and performing flatness detection on the hot-rolled steel plate blank to obtain an initial flatness detection result, wherein the initial flatness detection result comprises the plate shape of the hot-rolled steel plate blank.
In some embodiments, the step S4 specifically includes: and correcting the cooled flatness detection result by using the initial flatness detection result to obtain the plate shape of the steel plate blank caused by thermal expansion, and determining the difference of the cooling speed of the upper surface and the lower surface of the steel plate blank according to the corrected cooled flatness detection result. In order to more accurately obtain the influence of cooling on the steel plate shape, the flatness detection result can more accurately reflect the effect of cooling on the plate shape of the steel plate blank, the steel plate blank after hot rolling is subjected to flatness detection, and the effect of the hot rolling on the steel plate shape can be known and eliminated by utilizing the initial flatness detection result and the flatness detection result of the initial flatness detection result.
In some embodiments, the step S2 specifically includes: cooling the hot rolled steel plate slab to cool the steel plate slab to 560 ℃ to 600 ℃, wherein the cooling comprises laminar cooling.
According to the embodiment of the application, by selecting a proper steel grade, the steel grade is characterized in that the target cooling is 560-600 ℃ when cooling is carried out; during cooling, the steel plate blank of the type is cooled to 560-600 ℃, a temperature interval with a large amount of bainite and a temperature interval with martensite can be avoided, so that the influence of the phase change expansion on the plate shape is greatly weakened, the influence principle of the thermal expansion on the plate shape is determined only, and the influence of the phase change expansion in cooling on the plate shape can be eliminated.
In some embodiments, the method further comprises:
and S5, adjusting the cooling parameters according to the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank so as to reduce the difference of the cooling speeds of the upper surface and the lower surface, wherein the cooling parameters comprise at least one of the pressure, the water flow speed and the water flow rate of the upper cooling header and the lower cooling header and the water flow rate ratio of the upper cooling header and the lower cooling header.
According to the embodiment of the application, after the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank is determined, the cooling parameters can be adjusted, so that the difference of the cooling speeds of the upper surface and the lower surface is reduced, the shape of the steel plate is close to a straight line shape, and a good shape effect is achieved.
In some embodiments, the cooling parameter is a water flow ratio of the upper cooling header and the lower cooling header.
According to the embodiment of the application, the respective pressures, water flow rates of the upper cooling header and the lower cooling header, and the water flow rate ratios of the upper cooling header and the lower cooling header can all influence the cooling rates of the upper surface and the lower surface of the steel plate blank, wherein the cooling parameters which play a main role can be the water flow rate ratios of the upper cooling header and the lower cooling header, and the influence on the cooling rates of the upper surface and the lower surface of the steel plate blank is the greatest.
In a second aspect, embodiments of the present application provide a system for rapidly determining a cooling rate of a steel plate, as shown in fig. 4, the system including:
a hot rolling mill train 100 for hot rolling a steel plate slab;
a cooling apparatus 200 for cooling the hot rolled steel sheet slab, wherein the cooling apparatus comprises a laminar flow cooling device;
the flatness detection device 300 is used for performing real-time flatness detection on the cooled steel plate blank to obtain a cooled flatness detection result of the steel plate blank, wherein the cooled flatness detection result comprises the plate shape of the cooled steel plate blank;
and a cooling speed determining means 400 for determining a difference in cooling speed between the upper surface and the lower surface of the steel plate blank in the cooling apparatus based on the flatness detection result.
According to this application embodiment, in above-mentioned system, can roll, cool off the steel sheet etc. and after cooling arrangement was located to current straightness detection device, can detect the straightness of steel sheet, detect straightness detection result with straightness detection device in this application for confirm the difference of the cooling rate of steel sheet slab upper surface and lower surface in the cooling arrangement. Further, the operator may use the flatness detection results to determine the difference in cooling rates of the upper and lower surfaces of the steel sheet slab in the cooling apparatus, and may also use the flatness detection results through associated software, virtual devices, etc. to determine the difference in cooling rates of the upper and lower surfaces of the steel sheet slab in the cooling apparatus.
According to the embodiment of the present application, the cooling device 200 may be a laminar flow cooling device 220, and may also be an ultrafast cooling device 210 and a laminar flow cooling device 220; an upper cooling header 211 and a lower cooling header 212 are arranged in the ultra-fast cooling device 210; the laminar flow cooling apparatus 220 may be provided therein with an upper cooling header and a lower cooling header; the steel plate blank is conveyed by a conveying roller 500; between the cooling apparatus 200 and the take-up apparatus 600, the flatness detecting device 300 is provided, and the cooling speed determining device 400 may be further provided.
In some embodiments, the system further comprises:
and the cooling parameter adjusting device is used for adjusting the cooling parameters of the cooling equipment according to the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank so as to reduce the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank.
According to the embodiment of the application, after the difference of the cooling speed of the upper surface and the lower surface of the steel plate blank in the cooling device is determined, parameters in the cooling device can be regulated and controlled by people, and the cooling parameters of the cooling device can be regulated by corresponding devices, such as a cooling parameter regulating device, or by combining corresponding algorithms and the like.
In some embodiments, the flatness detecting apparatus further includes a flatness detector disposed at an end of the hot rolling mill train for performing flatness detection on the hot rolled steel sheet slab to obtain an initial flatness detection result;
and the cooling speed determining device is used for correcting the cooled flatness detection result by using the initial flatness detection result so as to obtain the plate shape of the steel plate blank caused by thermal expansion, and determining the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank according to the corrected cooled flatness detection result.
In order to more accurately obtain the influence of cooling on the shape of the steel plate and enable the flatness detection result to more accurately reflect the effect of cooling on the shape of the steel plate blank, the flatness detector at the tail end of the hot rolling unit can correct the shape of the steel plate in the cooling process, so that the shape of the steel plate blank caused by thermal expansion in the cooling process can be conveniently determined, and the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank in the cooling process can be determined.
Examples
The present disclosure is more particularly described in the following examples that are intended as illustrative only, since various modifications and changes within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are on a weight basis, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and the equipment used in the examples is commercially available.
Example 1
The production trade name is S460Q-Z, and the embodiment of the application provides a method for rapidly determining the cooling speed difference of a steel plate, which comprises the following steps:
s1, carrying out hot rolling on a steel plate blank, wherein the thickness of the steel plate blank is 20mm, and the width of the steel plate blank is 2040mm;
s2, cooling the hot-rolled steel plate blank, wherein the cooling comprises laminar flow cooling and ultra-fast cooling, and the target cooling temperature is 560 ℃;
s3, performing real-time flatness detection on the cooled steel plate blank to obtain a flatness detection result of the cooled steel plate blank, wherein the flatness detection result comprises the plate shape of the cooled steel plate blank;
and S4, determining the difference of the cooling speed of the upper surface and the lower surface of the steel plate blank according to the flatness detection result. The plate shape of the steel grade after cooling and before coiling is shown in FIG. 5.
Example 2
The production brand is CCS-B, and the embodiment of the application provides a method for quickly determining the cooling speed difference of steel plates, which comprises the following steps:
s1, carrying out hot rolling on a steel plate blank, wherein the thickness of the steel plate blank is 19.75mm, and the width of the steel plate blank is 2000mm;
s2, cooling the hot-rolled steel plate blank, wherein the cooling is laminar cooling, and the target cooling temperature is 590 ℃;
s3, performing real-time flatness detection on the cooled steel plate blank to obtain a flatness detection result of the cooled steel plate blank, wherein the flatness detection result comprises the plate shape of the cooled steel plate blank;
and S4, determining the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank according to the flatness detection result. The plate shape of the steel grade after cooling and before coiling is shown in FIG. 6.
Performance detection
By using an optical microscope, the steel sheets obtained in example 1 and example 2 were each wound up and then examined to obtain a metallographic structure as shown in fig. 7 and fig. 8, respectively, fig. 7 shows the metallographic structure of the steel sheet in example 1, the left picture shows the metallographic structure of the upper surface of the steel sheet, the right picture shows the metallographic structure of the lower surface of the steel sheet, and the comparison of the two pictures shows that the metallographic structures of the upper and lower surfaces are different, and it can be inferred that the cooling rates of the upper and lower surfaces are different. FIG. 8 is the metallographic structure of the steel plate of example 2, the left graph is the metallographic structure of the upper surface of the steel plate, the right graph is the metallographic structure of the lower surface of the steel plate, and the comparison of the two graphs shows that the metallographic structures of the upper and lower surfaces are different, and it can be inferred that the cooling rates of the upper and lower surfaces are different.
The steel plate in example 1 is in the shape of a turtle, and the cooling parameters in the cooling process in the steel production line production process in example 1 are adjusted, and the cooling parameters include at least one of the pressure, the water flow speed, and the water flow rate of the upper cooling header and the lower cooling header, and mainly include the water flow rate of the upper cooling header and the lower cooling header. The adjusting method specifically comprises the following steps: the opening of the upper header water valve was set to 100% and the opening of the lower header water valve was set to 75%, to obtain a steel plate shape as shown in fig. 9. After the coiling, the metallographic structure of the steel sheet was checked and the cooling parameters were adjusted, as shown in fig. 10, it was found that the metallographic structures of the upper and lower surfaces were substantially the same, and it was estimated that the cooling rates of the upper and lower surfaces were the same.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or substitutions within the technical scope of the present application, and these modifications or substitutions should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. A method for rapidly determining a difference in cooling rates of steel sheets, comprising the steps of:
s1, hot rolling a steel plate blank, wherein the thickness of the steel plate blank is more than 12mm, preferably more than 15 mm;
s2, cooling the hot-rolled steel plate blank, wherein the cooling comprises laminar flow cooling;
s3, performing real-time flatness detection on the cooled steel plate blank to obtain a cooled flatness detection result of the steel plate blank, wherein the cooled flatness detection result comprises the plate shape of the cooled steel plate blank;
and S4, determining the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank according to the detection result of the flatness after cooling.
2. The method of claim 1, wherein the cooling further comprises ultra-fast cooling, the ultra-fast cooling occurring prior to the laminar cooling.
3. The method of claim 1, wherein the step S1 further comprises: and performing flatness detection on the hot-rolled steel plate blank to obtain an initial flatness detection result, wherein the initial flatness detection result comprises the shape of the hot-rolled steel plate blank.
4. The method according to claim 3, wherein the step S4 specifically comprises: and correcting the cooled flatness detection result by using the initial flatness detection result to obtain the plate shape of the steel plate blank caused by thermal expansion, and determining the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank according to the corrected cooled flatness detection result.
5. The method according to claim 1, wherein the step S2 specifically comprises: cooling the hot rolled steel plate slab to cool the steel plate slab to 560 ℃ to 600 ℃, wherein the cooling comprises laminar cooling.
6. The method of claim 1, further comprising:
and S5, adjusting the cooling parameters according to the difference of the cooling speed of the upper surface and the lower surface of the steel plate blank so as to reduce the difference of the cooling speed of the upper surface and the lower surface, wherein the cooling parameters comprise at least one of pressure, water flow speed and water flow rate of the upper cooling header and the lower cooling header respectively and the water flow rate ratio of the upper cooling header and the lower cooling header.
7. The method of claim 6, wherein the cooling parameter is a water flow ratio of the upper cooling header and the lower cooling header.
8. A system for rapidly determining the cooling rate of a steel sheet, the system comprising:
the hot rolling unit is used for hot rolling the steel plate blank;
the cooling device is used for cooling the hot-rolled steel plate blank, and comprises a laminar flow cooling device;
the flatness detection device is used for performing real-time flatness detection on the cooled steel plate blank to obtain a cooled flatness detection result of the steel plate blank, wherein the cooled flatness detection result comprises the plate shape of the cooled steel plate blank;
and the cooling speed determining device is used for determining the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank in the cooling equipment according to the detection result of the flatness after cooling.
9. The system of claim 8, further comprising:
and the cooling parameter adjusting device is used for adjusting the cooling parameters of the cooling equipment according to the difference of the cooling speed of the upper surface and the lower surface of the steel plate blank so as to reduce the difference of the cooling speed of the upper surface and the lower surface of the steel plate blank.
10. The system of claim 9,
the flatness detection device also comprises a flatness detector arranged at the tail end of the hot rolling unit and used for detecting the flatness of the hot rolled steel plate blank so as to obtain an initial flatness detection result;
and the cooling speed determining device is used for correcting the cooled flatness detection result by using the initial flatness detection result so as to obtain the plate shape of the steel plate blank caused by thermal expansion, and determining the difference of the cooling speeds of the upper surface and the lower surface of the steel plate blank according to the corrected cooled flatness detection result.
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| CN202210978625.XA CN115488166A (en) | 2022-08-16 | 2022-08-16 | Method for rapidly determining difference of cooling speed of steel plate |
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| CN202210978625.XA CN115488166A (en) | 2022-08-16 | 2022-08-16 | Method for rapidly determining difference of cooling speed of steel plate |
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