CN115069771A - Hot-rolled steel coil and manufacturing method thereof - Google Patents
Hot-rolled steel coil and manufacturing method thereof Download PDFInfo
- Publication number
- CN115069771A CN115069771A CN202210722369.8A CN202210722369A CN115069771A CN 115069771 A CN115069771 A CN 115069771A CN 202210722369 A CN202210722369 A CN 202210722369A CN 115069771 A CN115069771 A CN 115069771A
- Authority
- CN
- China
- Prior art keywords
- steel strip
- temperature
- steel
- coiling
- strip
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 218
- 239000010959 steel Substances 0.000 title claims abstract description 218
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 24
- 238000001816 cooling Methods 0.000 claims abstract description 72
- 238000000034 method Methods 0.000 claims abstract description 37
- 238000010438 heat treatment Methods 0.000 claims abstract description 27
- 238000005096 rolling process Methods 0.000 claims abstract description 19
- 238000005266 casting Methods 0.000 claims abstract description 11
- 238000012937 correction Methods 0.000 claims description 11
- 238000002791 soaking Methods 0.000 claims description 10
- 230000008569 process Effects 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 10
- 230000008859 change Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000005457 optimization Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 4
- 229910001563 bainite Inorganic materials 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000005496 tempering Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000011218 segmentation Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Images
Classifications
-
- 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
-
- 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
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
The application provides a hot-rolled steel coil and a manufacturing method thereof. The method comprises the following steps: heating the casting blank; rolling the heated casting blank at the finishing temperature of 880-920 ℃ to obtain a steel strip; cooling the steel strip at a first stage cooling rate R 1 Cooling to a temperature of 640-650 ℃, and then cooling at a second stage cooling rate R 2 Cooling to coiling temperature T 1 And coiling different parts of the steel strip under different coiling temperature conditions to obtain the hot rolled steel coil. The application discloses a manufacturing method of a thin hot-rolled steel coil, which is suitable for manufacturing the hot-rolled steel coil with the thickness of less than or equal to 2.5mm, particularly the thickness of less than or equal to 2.0mm, and the ovality of the steel coil is less than 6% after the steel coil is stood for 48 hours, so that the steel coil can be normally uncoiled, the method is simple, the equipment does not need to be modified, the production cost is reduced, and the application range is wide.
Description
Technical Field
The application relates to the technical field of hot rolled steel plates, in particular to a hot rolled steel coil and a manufacturing method thereof.
Background
The requirement of light weight of automobiles puts higher weight reduction demands on steel materials. The range of application of hot rolled steels is also increasing as hot rolled steels (20MnB5, 22MnB5, etc.) that have both high strength and easy formability. However, in the actual production process, the hot-rolled thin hot-rolled steel with the thickness less than or equal to 2.5mm has the phenomenon of coil collapse (or flat coil), which occurs after ten seconds of coil unloading and is continuously deteriorated in the following hours. And the degree of roll collapse is increased along with the reduction of the thickness specification. Once the steel coil collapses, the steel coil needs to be shaped or the inner ring needs to be cut for subsequent production, so that the labor intensity is greatly increased, and the production efficiency and the yield are seriously influenced.
Disclosure of Invention
The application provides a hot-rolled steel coil and a manufacturing method thereof, which aim to solve the problem that the hot-rolled steel coil with the thickness specification less than or equal to 2.5mm is easy to collapse in the prior art.
In a first aspect, the present application provides a method for manufacturing a hot-rolled steel coil, comprising the steps of:
s10, heating the casting blank;
s20, rolling the heated casting blank at the finish rolling temperature of 880-920 ℃ to obtain a steel strip;
s30 cooling the steel strip at a first stage cooling rate R 1 Cooling to 640-650 ℃, wherein R is less than or equal to 80 ℃/s 1 140 ℃/s or less, followed by a second stage cooling rate R 2 Cooling to coiling temperature T 1 Wherein R is more than or equal to 15 ℃/s 2 ≤55℃/s,100℃≤T 1 ≤630℃；
S40 coiling the steel strip to obtain the hot rolled steel coil,
wherein the coiling comprises:
at the temperature T of the strip being wound 2 T is more than 580 DEG C 2 Coiling the steel strip 1-2 m in front of the rolling head at the temperature of not more than 630 ℃;
at the temperature T of the strip being wound 3 T is more than or equal to 100 DEG C 3 Coiling the subsequent 10-12 m steel strip at the temperature of less than or equal to 300 ℃;
at the temperature T of the strip being wound 4 ＝550℃-k 3 ×a 1/2 Coiling the subsequent steel strip at the normal position under the condition of x b +/-10 ℃;
wherein a represents the thickness of the steel strip in mm;
b represents the width of the steel strip in mm;
k 3 a correction coefficient of 11.8X 10 indicating a coiling temperature -3 ℃/mm 3/2 。
In the technical scheme of this application, through the cooling mode that adopts "strong cold + weak cold", reduced the volume proportion of cooling to coiling in-process phase transition, and adopt different coiling temperatures to the different positions of steel band, the part that the low temperature was coiled can act as the sleeve effect. Therefore, the hot-rolled steel coil manufactured by the method for manufacturing the hot-rolled steel coil provided by the application is not easy to collapse.
In some embodiments of the present application, the heating process comprises a pre-heating stage process, a first heating stage process, a second heating stage process, and a soaking stage process, wherein the temperature of the second heating stage process and the soaking stage process are both 1120 ℃ to 1200 ℃.
In some embodiments of the present application, in step S30, the first segment cooling rate R 1 ＝90℃/s+k 1 ×a 1/2 ±10℃/s，
Wherein a represents the thickness of the steel strip in mm;
k 1 indicating the first stage cooling rateThe correction coefficient of (a) is 21.2 ℃/s.mm 1/2 。
In some embodiments of the present application, in step S30, the second segment cooling rate R 2 ＝25℃/s+k 2 ×a 1/2 ±10℃/s，
Wherein a represents the thickness of the steel strip in mm;
k 2 a correction coefficient of 14.8 ℃/s.mm, which represents a cooling rate in the second stage 1/2 。
In some embodiments of the present application, the steel strip has a thickness of ≦ 2.5mm, optionally < 2 mm.
In a second aspect, the present application provides a hot rolled steel coil manufactured by the manufacturing method according to any one of the above embodiments.
According to the technical scheme, the hot rolled steel coil is not prone to collapse, and the uncoiling rate is high in the subsequent treatment link.
In some embodiments of the present application, the ovality of the coil is < 6% after standing for 48 hours.
In some embodiments of the application, the yield strength of the steel strip at the normal part is more than or equal to 450 MPa;
optionally, the tensile strength of the steel strip at the normal part is within the range of 600MPa to 720 MPa;
optionally, the elongation of the steel belt at the normal position is more than or equal to 23%.
In some embodiments of the application, the yield strength of the steel strip at the position of 3-8 m of the head part is more than or equal to 550 MPa;
optionally, the tensile strength of the steel strip at the position 3m to 8m of the head part is within the range of 660MPa to 760 MPa;
optionally, the elongation of the steel belt at the position of 3-8 m of the head part is more than or equal to 17%.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.
Fig. 1 is an example of a coiling temperature profile employed in the examples of the present application.
FIG. 2 is a view showing the shape of a 1.8mm hot rolled steel coil manufactured in example 5 of the present application when it is unwound.
FIG. 3 shows the shape of a 1.8mm hot-rolled steel coil produced in example 5 of the present application after it has been left to stand for 48 hours.
FIG. 4 is a drawing showing the shape of a 1.8mm hot-rolled steel coil manufactured in comparative example 2 in the present application when it is unwound.
FIG. 5 is a drawing showing the shape of a 1.8mm hot rolled steel coil manufactured in comparative example 2 of the present application after it is left standing for 48 hours.
With the above figures, there are shown specific embodiments of the present application, which will be described in more detail below. These drawings and written description are not intended to limit the scope of the inventive concepts in any manner, but rather to illustrate the inventive concepts to those skilled in the art by reference to specific embodiments.
Detailed Description
The examples or embodiments are described in a progressive arrangement throughout this specification, each with emphasis on illustrating differences from the other examples.
In the description herein, references to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
The applicant notices that the thin hot rolled steel coil manufactured by the existing method is easy to collapse, the phenomenon can occur quickly after coil unloading, meanwhile, deterioration continues to occur within the following hours, the thinner the steel strip is, the more serious the coil collapsing phenomenon is, the steel coil after collapse cannot be installed on a machine in the following processing, the flame cutting needs to be carried out on the inner ring of the steel coil, the production efficiency is reduced, the labor intensity is increased, and the production cost is increased.
For the problem of collapse of a steel coil, the current basic methods include storage and transportation by a vertical coil mode or modification of a saddle, optimization of parameters such as coiling tension, optimization of uncoiling processes or modification of uncoiling equipment and optimization of coiling temperature.
However, in these methods, the cost is greatly increased and is not paid; the parameters are difficult to control by part of methods, different optimization needs to be carried out on different materials, and the application range is small; the optimization of coiling temperature is a relatively ideal method, but the optimization has certain problems, and the effect on hot rolled steel with the thickness less than or equal to 2.5mm, particularly the thickness less than 2mm, is limited.
One aspect of the present application provides a method of manufacturing a hot-rolled steel coil, including the steps of:
s10, heating the casting blank;
s20, rolling the heated casting blank at the finish rolling temperature of 880-920 ℃ to obtain a steel strip;
s30 cooling the steel strip at a first stage cooling rate R 1 Cooling to 640-650 ℃, wherein R is less than or equal to 80 ℃/s 1 140 ℃/s or less, followed by a second stage cooling rate R 2 Cooling to coiling temperature T 1 Wherein R is more than or equal to 15 ℃/s 2 ≤55℃/s,100℃≤T 1 ≤630℃；
S40 coiling the steel strip to obtain the hot rolled steel coil,
wherein the coiling comprises:
at the temperature T of the strip being wound 2 T is more than 580 DEG C 2 Coiling the steel strip 1-2 m in front of the rolling head at the temperature of not more than 630 ℃;
at the temperature T of the strip being wound 3 T is more than or equal to 100 DEG C 3 Coiling the subsequent 10-12 m steel strip at the temperature of less than or equal to 300 ℃;
at the temperature T of the strip being wound 4 ＝550℃-k 3 ×a 1/2 Coiling the subsequent steel strip at the normal position under the condition of x b +/-10 ℃;
wherein a represents the thickness of the steel strip in mm;
b represents the width of the steel strip in mm;
k 3 a correction coefficient of 11.8X 10 indicating a coiling temperature -3 ℃/mm 3/2 。
In some embodiments, the heating treatment in the S10 step includes a preheating stage treatment, a first heating stage treatment, a second heating stage treatment, and a soaking stage treatment, wherein the temperatures of the second heating stage treatment and the soaking stage treatment are 1120 ℃ to 1200 ℃.
In some embodiments, the temperature of the second heating section treatment and the soaking section treatment is controlled within the range of 1120-1200 ℃, so that the casting blank is heated sufficiently, and austenite grains are prevented from being coarse.
According to the embodiment of the application, in the step S20, the finishing temperature is controlled to be in the range of 880-920 ℃, so that the rolling force can be reduced, and the tail part of the hot rolled steel can be prevented from rolling in a two-phase region.
According to an embodiment of the present application, the step S30 employs two-stage cooling with a strong first stage and a weak second stage. By applying a cooling rate R in the first stage 1 R is more than or equal to 80 ℃/s 1 The steel strip is cooled to 640-650 ℃ under the strong cooling condition of less than or equal to 140 ℃/s, so that the steel strip can be rapidly cooled to the temperature (660 ℃) below the nose tip of the phase change of the hot rolled steel, thereby avoiding the large-area phase change of the steel strip in a short time and simultaneously reducing the thickness of an intergranular oxide layer on the surface of the steel strip. On the contrary, if a large amount of phase change occurs to the steel strip in the cooling process, the volume of the steel strip is expanded in the coiling process after cooling, so that the tension fluctuation in the coiling process is caused, and the coiling effect is influenced.
Further, according to an embodiment of the present application, in the step S30, the second stage cooling uses weak cooling. By applying a cooling rate R in the second stage 2 R is not less than 15 ℃/s 2 The weak cooling of less than or equal to 55 ℃/s cools the steel strip to the coiling temperature T suitable for the next coiling 1 The steel strip can release and eliminate the internal stress generated in the strong cooling process, and the warping of the hot rolled steel in the subsequent processing and blanking link is prevented. The starting temperature of the second stage weak cooling is reduced to be lower than the nose tip temperature of the phase transformation, so the second stage weak cooling can not cause large-area phase transformation of the hot rolled steel.
In some embodiments, step S30 is the cooling rate R employed in the first stage of intense cooling 1 ＝90℃/s+k 1 ×a 1/2 +/-10 ℃/s, wherein a represents the thickness of the steel strip and is in mm; k is a radical of 1 A correction coefficient of 21.2 ℃/s-mm representing the cooling rate in the first stage 1/2 。
In this embodiment, the cooling rate of the first stage of forced cooling is adjusted according to the thickness of the steel strip, so that the process conditions can be better optimized for the steel strips with different thicknesses, and the phase change of the steel strips with different thicknesses can be more effectively controlled.
In some embodiments, step S30 is the cooling rate R used in the second stage of weak cold 2 ＝25℃/s+k 2 ×a 1/2 +/-10 ℃/s, wherein a represents the thickness of the steel strip and is in mm; k is a radical of 2 A correction coefficient of 14.8 ℃/s.mm, which represents a cooling rate in the second stage 1/2 。
In the embodiment, the cooling rate of the second stage of weak cooling is adjusted according to the thickness of the steel strip, so that the process conditions can be better optimized for the steel strips with different thicknesses, and the internal stress of the steel strips with different thicknesses can be more effectively released and eliminated.
According to an embodiment of the present application, the winding step S40 mainly includes three stages:
at the temperature T of the strip being wound 2 T is more than 580 DEG C 2 Coiling the steel strip 1-2 m in front of the rolling head at the temperature of not more than 630 ℃;
at the temperature T of the strip being wound 3 Meets the requirement of 100 ℃ or lowerT 3 Coiling the subsequent 10-12 m steel strip at the temperature of less than or equal to 300 ℃;
at the temperature T of the strip being wound 4 ＝550℃-k 3 ×a 1/2 Coiling the subsequent steel strip at the normal position under the condition of x b +/-10 ℃, wherein a represents the thickness of the steel strip and has the unit of mm; b represents the width of the steel strip in mm; k is a radical of 3 A correction coefficient of 11.8X 10 indicating a coiling temperature -3 ℃/mm 3/2 。
Fig. 1 shows an example of a coiling temperature profile employed in the embodiment of the present application.
According to the application, and with reference to FIG. 1, in the coiling of the first section of strip (strip 1-2 m before the rolling head), the temperature 580 ℃ < T of the strip to be coiled 2 630 ℃ or less, which can ensure that the steel strip normally enters the coiler.
According to the application, and with reference to FIG. 1, when coiling a second section of strip (strip 10-12 m after the first section) the temperature T of the strip being coiled is such that 3 T is more than or equal to 100 DEG C 3 Is less than or equal to 300 ℃. Under such coiling temperature conditions, the second-stage coiled steel strip can have a martensite + bainite structure. According to the application, the length of the coiled second section of steel strip is about 4-5 circles, and the inner circle of the steel coil is formed. The formed inner ring steel belt has martensite + bainite structures, so that high rigidity is ensured, and the inner ring steel belt can play a role of a sleeve, thereby effectively preventing coil collapse. Meanwhile, if the length of the second section of steel strip is insufficient, the second section of steel strip also cannot play a role of a sleeve, and the second section of steel strip is too long, so that the second section of steel strip cannot be tempered sufficiently in the coiling process to reduce the strength. In addition, the specific 'strong cooling plus weak cooling' two-stage cooling is adopted in the method, so that the steel strip to be coiled has controlled transformation degree and internal stress, and the method is very suitable for the second-stage low-temperature coiling in the step to form the steel coil inner ring with expected internal metallographic structure and higher rigidity. If the temperature of the steel strip coiled by the second section is too high, a steel coil inner ring with enough rigidity cannot be obtained. If the temperature of the steel strip is too low during the second section of coiling, the subsequent tempering temperature is high, otherwise the tempering degree is not enough, and the strength is highAnd (4) exceeding the standard.
According to the present application, and with reference to FIG. 1, when coiling a third section of strip (the remainder of the strip after the second section), the temperature T of the strip being coiled is made to be such 4 ＝550℃-k 3 ×a 1/2 X b +/-10 ℃, wherein a represents the thickness of the steel strip and the unit is mm; b represents the width of the steel strip in mm; k is a radical of 3 A correction coefficient of 11.8X 10 indicating a coiling temperature -3 ℃/mm 3/2 . According to the embodiment of the present application, the steel strip of the normal portion wound in the third winding constitutes a main portion of the hot rolled steel coil. The coiling temperature is further adjusted based on the thickness and the width of the steel strip on the basis of the normal coiling temperature, so that the process conditions can be better optimized for the steel strips with different thicknesses, and the obtained steel strip at the normal position can completely meet the standard excellent performance. If the temperature of the part is too high, the second section of the steel coil at the low temperature coiling part is quickly tempered, so that the strength of the steel coil is quickly reduced, and the function of a sleeve is lost. The temperature of the normal part is too low, the mechanical property of the normal part exceeds the upper limit of the standard, and the inner ring cannot be tempered, so that the strength of the second section of low-temperature coiling part is ultrahigh.
In some embodiments, the steel strip has a thickness of ≦ 2.5mm, preferably < 2 mm.
The thinner the thickness of the steel strip is, the more easily the steel coil obtained by coiling the steel strip collapses, and in the prior art, when the thickness of the steel coil is less than or equal to 2.5mm, the more easily the steel coil collapses, and the thinner the steel coil, the more aggravated the degree of the collapse. According to the method, specific 'strong cooling and weak cooling' two-section type cooling is combined with specific three-section coiling, and key process parameters can be optimized according to the thickness of the steel strip. The method of the application is therefore particularly suitable for producing hot-rolled steel coils having a strip thickness of < 2.5mm, more preferably < 2 mm. When the thickness of the steel strip is less than or equal to 2.5mm, and more preferably less than 2mm, the hot rolled steel coil manufactured by the method is not easy to collapse, and the performance of the obtained product can be ensured to completely meet the standard requirement.
Another aspect of the present application also provides a hot-rolled steel coil manufactured by the manufacturing method of the above-described embodiment. Therefore, the hot rolled steel coil provided by the application is not easy to collapse, and the uncoiling rate is high in the subsequent treatment link.
In some embodiments, the ovality of the coil after standing for 48 hours is measured to be < 6%.
In this example, the ovality of the coil after standing for 48 hours was < 6%. Because the inner diameter of a standard hot rolled steel coil is 760mm, the phenomenon of coil loosening is generally generated at the first circle of the inner ring, and the actual diameter is about 740 mm. The diameter of a coil core of the uncoiler is 690mm, and when the minimum diameter of the collapsed steel coil is less than 700mm, the steel coil cannot be normally operated, and flame cutting needs to be carried out on an inner ring. As can be seen from the ellipse circumference calculation formula and the calculation formula of ovality ═ maximum outer diameter-minimum outer diameter)/nominal outer diameter × 100%, the ovality in this case is 8.1%. I.e. the ovality is less than or equal to 8 percent, and can ensure the normal uncoiling of the steel coil.
In some embodiments of the application, the yield strength of the steel belt at the normal part is more than or equal to 450MPa, the tensile strength is in the range of 600-720 MPa, and the elongation is more than or equal to 23%.
In the embodiment, the yield strength of the steel belt at the normal position is more than or equal to 450MPa, the tensile strength is within the range of 600-720 MPa, and the elongation is more than or equal to 23 percent through detection. The steel strip of normal position constitutes the essential part of hot rolled steel coil, through specific two segmentation cooling for the steel strip that waits to batch has controlled phase transition degree and internal stress, and combine to batch the in-process, further optimizes the batching temperature through thickness and the width based on the steel strip on the basis of normal coiling temperature, thereby guarantees that the steel strip of gained normal position satisfies the excellent performance of standard completely, and above-mentioned each index all satisfies the delivery standard of hot rolled steel coil.
In some embodiments, the yield strength of the steel strip at the position of 3-8 m of the head is more than or equal to 550MPa, the tensile strength is in the range of 660-760 MPa, and the elongation is more than or equal to 17%.
In the embodiment, the detection shows that the yield strength of the steel belt at the position of 3-8 m of the head part is more than or equal to 550MPa, the tensile strength is in the range of 660-760 MPa, and the elongation is more than or equal to 17%. The steel strip at the position of 3-8 m of the head belongs to the steel strip part which is coiled at low temperature at the second section, and forms a steel coil inner ring with higher rigidity, and the strength is slowly reduced in the tempering process under the heat transfer condition of a normal part. All indexes of the product can still meet delivery standards, no material waste is caused, and the cost is saved.
Hereinafter, the present application will be described in more detail with reference to examples of hot rolled steel 22MnB5, but the present application is not limited to these examples at all.
In the following examples and comparative examples, hot-rolled steel coils according to embodiments of the present application were manufactured under various conditions, and the measurement of the strip thickness, strip width, mechanical properties, and coil shape of the obtained hot-rolled steel coils was performed, in which the strip thickness, strip width were directly measured; the mechanical property is tested according to the method in GB/T232-2010; the coil shape is characterized by ovality, and the smaller the ovality, the better the coil shape is considered, and the performance test results of the hot-rolled steel coils manufactured in the examples are shown in table 2, which are calculated by ovality (maximum outer diameter-minimum outer diameter)/nominal outer diameter × 100%.
Example 1
S10, heating the casting blank, wherein the heating comprises preheating section treatment, first heating section treatment, second heating section treatment and soaking section treatment, and the temperatures of the second heating section treatment and the soaking section treatment are 1160 ℃. (ii) a
S20, rolling the heated casting blank at the finish rolling temperature of 910 ℃ to obtain a steel strip;
s30 cooling the strip to 650 ℃ at a first stage cooling rate of 131 ℃/S and subsequently to a coiling temperature T at a second stage cooling rate of 53 ℃/S 1 Wherein T is more than or equal to 100 DEG C 1 ≤630℃；
S40 coiling the steel strip to obtain the hot rolled steel coil,
wherein the coiling comprises:
at the temperature T of the strip being wound 2 T is more than 580 DEG C 2 Coiling the steel strip 1m in front of the rolling head at the temperature of less than or equal to 630 ℃;
at the temperature T of the strip being wound 3 T is more than or equal to 100 DEG C 3 Coiling the subsequent 10m steel strip at the temperature of less than or equal to 300 ℃;
the steel strip at the subsequent normal portion was coiled at a temperature of 515 ℃ of the coiled steel strip.
Example 2
This example differs from example 1 in that: for the differences of the reaction parameters, please refer to table 1.
Example 3
This example differs from example 1 in that: for the differences of the reaction parameters, please refer to table 1.
Example 4
This example differs from example 1 in that: for the differences of the reaction parameters, please refer to table 1.
Example 5
This example differs from example 1 in that: for the differences of the reaction parameters, please refer to table 1.
Example 6
This example differs from example 1 in that: for the differences of the reaction parameters, please refer to table 1.
Example 7
This example differs from example 1 in that: for the differences of the reaction parameters, please refer to table 1.
Example 8
This example differs from example 1 in that: for the differences of the reaction parameters, please refer to table 1.
Comparative example 1
This example differs from example 1 in that: for the differences of the reaction parameters, please refer to table 1.
Comparative example 2
This example differs from example 1 in that: for the differences of the reaction parameters, please refer to table 1.
Comparative example 3
This example differs from example 1 in that: for the differences of the reaction parameters, please refer to table 1.
TABLE 1
Note: t is Heating is carried out The temperature representing the second heating stage treatment and soaking stage treatment in step S10, in units of;
T finish rolling Represents the finish rolling temperature in step S20, and has the unit of;
R 1 represents the first stage cooling rate in step S30 in deg.c/S;
R 2 represents the second stage cooling rate in step S30 in units of ℃/S;
T 4 a coiling temperature of the steel strip representing the normal portion in the step S40, in units of ℃;
L low temperature coiling Represents the length of the steel strip wound at 100 to 300 ℃ in step S40;
T 2-8 m coiling The average coiling temperature of the steel strip at the position of 2-8 m of the head part in the step S40 is shown.
TABLE 2
Note: a represents the thickness of the steel strip in mm;
b represents the width of the steel strip in mm;
R eL the yield strength of the steel strip at the normal position is expressed in MPa;
R m the tensile strength of the steel strip at the normal position is expressed in MPa;
a represents the elongation percentage of the steel strip at the normal position, and the unit is%;
epsilon represents the ovality of the steel coil after standing for 48 hours, and the unit is percent.
Fig. 2 and 4 are coil shape pictures at the time of unwinding the 1.8mm hot rolled steel coil manufactured in example 5 and comparative example 2, respectively.
The inner diameter of a standard hot-rolled steel coil is 760mm, and generally, the coil loosening phenomenon exists in the first circle of an inner ring, and the actual diameter is about 740 mm. The diameter of a coil core of the uncoiler is 690mm, and when the minimum diameter of the collapsed steel coil is less than 700mm, the steel coil cannot be normally operated, and flame cutting needs to be carried out on an inner ring. As can be seen from the ellipse circumference calculation formula and the calculation formula of ovality ═ maximum outer diameter-minimum outer diameter)/nominal outer diameter × 100%, the ovality in this case is 8.1%. I.e. the ovality is less than or equal to 8 percent, and can ensure the normal uncoiling of the steel coil.
FIGS. 3 and 5 are photographs of the coil shapes of 1.8mm hot rolled steel coils manufactured in example 5 and comparative example 2, respectively, after being left for 48 hours.
As can be seen from Table 2, the steel strip thickness of the steel coils prepared in the embodiments 1 to 8 is less than or equal to 2.5mm, the ovality of the steel coils after standing for 48 hours is less than 6%, and the normal uncoiling rate is 100%; the thickness of the steel strip of the steel coil prepared in the comparative examples 1-3 is less than or equal to 2.5mm, the ovality of the steel coil is more than 8% after standing for 48 hours, and the steel coil can not be normally uncoiled without treatment. The reason for this is that: the coiling temperature of the steel strip at the normal position in the comparative example 1 is 593 ℃, the steel coil is subjected to phase change and temperature rise after coiling, the inner ring is rapidly tempered, the strength is reduced, the steel coil cannot play a role of a steel sleeve, the ovality of the steel coil is 9.1% after standing for 48 hours, namely the minimum diameter is 697mm, normal machine uncoiling cannot be realized without treatment, and the comparative example 1 adopts a uniform cooling method, so that a large amount of phase change occurs in the cooling process, the internal stress of the steel strip is large, and the coil collapse is easy to occur; in the comparative example 2, the average temperature of the head part 2-8 m is 478 ℃, so that a martensite + bainite structure cannot be formed, the strength and rigidity of an inner ring are insufficient, the ovality of a steel coil is 10.4% after the steel coil is stood for 48 hours, namely the minimum diameter is 690mm and is smaller than the minimum diameter requirement of uncoiling, and the comparative example 2 adopts a cooling mode of firstly carrying out weak cooling and then carrying out strong cooling, so that the internal stress of the steel strip is large, the plate profile is poor, and the coil collapse is easy to occur; in comparative example 3, the length of the low-temperature coiling is 4m, the coiling temperature of the normal part is too high, the length of the inner ring coiled at the low temperature is too short, and meanwhile, the temperature of the normal part is too high, so that the inner ring is rapidly tempered, the sleeve effect is lost, the thickness of the inner ring is thin, and the coil collapsing phenomenon is more likely to occur, therefore, the ovality of the steel coil is 12.6 percent after standing for 48 hours, namely the minimum diameter is 681mm and is far smaller than the diameter requirement of uncoiling.
In addition, 3 m-8 m of the inner ring of the steel coil prepared in each embodiment is sampled, the tensile strength is measured to be about 40 MPa-60 MPa higher than that of the normal part, the elongation is about 4-6% lower, the steel strip at the position of 3 m-8 m of the head part belongs to the steel strip part which is coiled at the second section, and after the steel coil is coiled at low temperature, the steel coil inner ring with higher rigidity can still meet the delivery standard by virtue of specific 'strong cooling + weak cooling' two-section cooling, and each index of the steel coil inner ring is good in plate shape, so that the waste of materials can not be caused, and the cost is saved.
Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.
Claims (9)
1. A method for manufacturing a hot-rolled steel coil, characterized by comprising the steps of:
s10, heating the casting blank;
s20, rolling the heated casting blank at the finish rolling temperature of 880-920 ℃ to obtain a steel strip;
s30 cooling the steel strip at a first stage cooling rate R 1 Cooling to 640-650 ℃, wherein R is less than or equal to 80 ℃/s 1 140 ℃/s or less, followed by a second stage cooling rate R 2 Cooling to coiling temperature T 1 Wherein R is more than or equal to 15 ℃/s 2 ≤55℃/s,100℃≤T 1 ≤630℃；
S40 coiling the steel strip to obtain the hot rolled steel coil,
wherein the coiling comprises:
at the temperature T of the strip being wound 2 T is more than 580 DEG C 2 Coiling the steel strip 1-2 m in front of the rolling head at the temperature of not more than 630 ℃;
at the temperature T of the strip being wound 3 T is more than or equal to 100 DEG C 3 Coiling the subsequent 10-12 m steel strip at the temperature of less than or equal to 300 ℃;
at the temperature T of the strip being wound 4 ＝550℃-k 3 ×a 1/2 Coiling the subsequent steel strip at the normal position under the condition of x b +/-10 ℃;
wherein a represents the thickness of the steel strip in mm;
b represents the width of the steel strip in mm;
k 3 a correction coefficient of 11.8X 10 indicating a coiling temperature -3 ℃/mm 3/2 。
2. The manufacturing method according to claim 1, wherein in step S10, the heating treatment includes a pre-heating stage treatment, a first heating stage treatment, a second heating stage treatment, and a soaking stage treatment, wherein the heating temperature of the second heating stage treatment and the soaking stage treatment is 1120 ℃ to 1200 ℃.
3. The manufacturing method according to claim 1, wherein in step S30, the first segment cooling rate R 1 ＝90℃/s+k 1 ×a 1/2 ±10℃/s，
Wherein a represents the thickness of the steel strip in mm;
k 1 a correction coefficient of 21.2 ℃/s-mm representing the cooling rate in the first stage 1/2 。
4. The production method according to claim 1 or 3, wherein the second stage cooling rate R is in step S30 2 ＝25℃/s+k 2 ×a 1/2 ±10℃/s，
Wherein a represents the thickness of the steel strip in mm;
k 2 a correction coefficient of 14.8 ℃/s.mm, which represents a cooling rate in the second stage 1/2 。
5. A method of manufacture according to claim 4, wherein the steel strip has a thickness of ≦ 2.5mm, optionally < 2 mm.
6. A hot rolled steel coil produced by the method for producing a thin gauge hot rolled steel coil according to any one of claims 1 to 5.
7. The hot rolled steel coil as claimed in claim 6, wherein the ovality of the coil after standing for 48 hours is < 6%.
8. The hot rolled steel coil as claimed in claim 6, wherein the yield strength of the normal portion steel strip is not less than 450 MPa;
optionally, the tensile strength of the steel strip at the normal position is within the range of 600MPa to 720 MPa;
optionally, the elongation of the steel belt at the normal position is more than or equal to 23%.
9. The hot-rolled steel coil as claimed in claim 6, wherein the yield strength of the steel strip at the position 3m to 8m of the head is not less than 550 MPa;
optionally, the tensile strength of the steel strip at the position 3m to 8m of the head part is within the range of 660MPa to 760 MPa;
optionally, the elongation of the steel belt at the position of 3-8 m of the head part is more than or equal to 17%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210722369.8A CN115069771A (en) | 2022-06-24 | 2022-06-24 | Hot-rolled steel coil and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210722369.8A CN115069771A (en) | 2022-06-24 | 2022-06-24 | Hot-rolled steel coil and manufacturing method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115069771A true CN115069771A (en) | 2022-09-20 |
Family
ID=83255947
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210722369.8A Pending CN115069771A (en) | 2022-06-24 | 2022-06-24 | Hot-rolled steel coil and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115069771A (en) |
-
2022
- 2022-06-24 CN CN202210722369.8A patent/CN115069771A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5162924B2 (en) | Steel plate for can and manufacturing method thereof | |
| CN111570517B (en) | Coiling control method for producing hot formed steel by thin slab continuous casting and rolling | |
| JP7008532B2 (en) | Cold rolling method | |
| JP6252499B2 (en) | Manufacturing method of hot-rolled steel strip, cold-rolled steel strip and hot-rolled steel strip | |
| CN111408625B (en) | Flat coil control method for hot rolling advanced high-strength steel | |
| CN115069771A (en) | Hot-rolled steel coil and manufacturing method thereof | |
| KR101611770B1 (en) | High cabon steel wire having excellent mechanical descaling property and method for manufacturing the same | |
| JP6350322B2 (en) | Manufacturing method and processing facility for high-strength steel sheet | |
| JP6070616B2 (en) | Manufacturing method of hot-rolled steel sheet | |
| KR101490600B1 (en) | Method for manufacturing wire rod | |
| JP5655839B2 (en) | Hot-rolled steel sheet used as a base material for steel sheet for can and manufacturing method thereof | |
| JPH10330847A (en) | Method for directly softening hot rolled wire rod | |
| KR102462023B1 (en) | Cooling method for reducing coil collapse in hot rolling mill of extra strength coil rolled steel | |
| CN114054502B (en) | Season-based flat roll control method for thin medium-high carbon steel seeds | |
| KR101657844B1 (en) | High cabon steel wire having excellent mechanical descaling property and method for manufacturing the same | |
| JP3145419B2 (en) | Manufacturing method of hot-rolled high-strength steel sheet with excellent material uniformity | |
| JP2020015947A (en) | Method for manufacturing hot-rolled coil and method for manufacturing non-oriented electromagnetic steel sheet | |
| CN100547089C (en) | The method for winding of metal bar | |
| JP2015116596A (en) | Method for production of hot-rolled steel strip | |
| JP2790730B2 (en) | Manufacturing method of high carbon steel sheet with excellent material uniformity | |
| JP5383141B2 (en) | Coil cooling method after hot rolling | |
| KR100482201B1 (en) | Method for hot rolled steel sheet having excellent coiling quality for line pipe | |
| CN115647074A (en) | Hot-rolled flat coil control method based on inner ring rigidity control | |
| JP2022146666A (en) | Method for manufacturing hot rolled coil | |
| KR100328070B1 (en) | A Method of Manufacturing wire for special welding rod |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |