Method of controlling hot rolling head imprint of a gapless atomic steel and a gapless atomic steel coil

Abstract

The application provides a method for controlling head imprint of hot rolling of interstitial-free steel and an interstitial-free steel coil, and comprises the following steps: cooling a slab of the interstitial-free steel after rolling treatment, and then winding the slab by using a three-roller winder at a preset temperature to obtain a steel coil; during the winding, the winding temperature of a head region of 20 m long at the head of the slab is lower than the preset temperature by 30 DEG C, and before the winding assisting roller of the three-roller winder is fully opened, the pressure control rotation position control is performed according to the following process to set the KP value of a segmented oil cylinder servo valve. The method can effectively control the head imprint, and can effectively control the steel coil of IF steel with a thickness of less than or equal to 3.0 mm.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy, in particular to a method for controlling head imprint of hot-rolled interstitial-free steel and an interstitial-free steel coil. BACKGROUND

[0002] Interstitial-free steel, also known as IF steel, has excellent deep drawing performance, high plastic strain ratio, high elongation, high hardening index, low yield ratio and excellent non-ageing property, and is therefore known as the third generation of ultra-deep drawing steel. Its excellent performance makes it widely used in automobile production. However, there are still many problems to be solved in hot-rolling production, especially when producing steel coils with a thickness of ≤3.0 mm. The head of the steel coil often has 1-3 tongue imprints with a depth fluctuation of more than 10%. Even if the cold rolling process is used, the imprints cannot be removed. When cold rolling at high speed, the severe thickness fluctuation at the imprint position is easy to cause tearing and belt breakage, which seriously affects the cold rolling production and causes serious cost and quality loss.

[0003] Some prior arts have studied the tongue imprint problem of hot-rolled steel strips, but there is no good control measure for the head imprint of IF steel coils with a thickness of ≤3.0 mm, especially when the head coil is tightly wound and cannot be loosened. The conflict between various measures to control the head imprint has not been well solved.

[0004] Therefore, the traditional technology still needs to be improved. SUMMARY

[0005] Based on this, the present application provides a method for controlling head imprint of hot-rolled interstitial-free steel and an interstitial-free steel coil, which can effectively control and reduce the head imprint of hot-rolled interstitial-free steel, and obtain a steel coil with good performance.

[0006] The technical scheme of the present application is as follows.

[0007] In a first aspect, the present application provides a method for controlling head imprint of hot-rolled interstitial-free steel, comprising the following steps:

[0008] cooling the slab of the interstitial-free steel after the rolling treatment, and then winding the slab at a preset temperature by using a three-roll winder to obtain a steel coil;

[0009] In the winding process, the winding temperature of the head region of 20 m long at the head of the slab is lower than the preset temperature by 30℃, and before the winding roll of the three-roll winder is completely opened, the pressure control is controlled, and the following process is performed:

[0010] When the actual value of the head pressure of the assisting roll is greater than the reference pressure value, the KP value of the oil cylinder servo valve of the assisting roll WR1 is set to 20, the KP value of the oil cylinder servo valve of the assisting roll WR2 is set to 22, and the KP value of the oil cylinder servo valve of the assisting roll WR3 is set to 24;

[0011] When the actual value of the head pressure of the assisting roll is less than or equal to the reference pressure value, the KP value of the oil cylinder servo valve of the assisting roll WR1 is set to 16, the KP value of the oil cylinder servo valve of the assisting roll WR2 is set to 18, and the KP value of the oil cylinder servo valve of the assisting roll WR3 is set to 20.

[0012] In the above method, the head yield strength is increased by reducing the head coiling temperature, thereby affecting the pressure on the assisting roll of the coiler, and the KP value of the oil cylinder servo valve of the assisting roll of the coiler is set according to the pressure control and position control, that is, when the pressure is greater than the reference pressure value, the KP value of the oil cylinder servo valve is controlled to quickly open the assisting roll, and when the pressure is less than or equal to the reference pressure value, the KP value of the oil cylinder servo valve is controlled to open the assisting roll at an appropriate speed, so as to solve the problem of head tongue imprint caused by slow response of the pressure control and position control before the assisting roll is completely opened.

[0013] Further, the above method of controlling the head imprint of the hot-rolled head of the gapless atomic steel can effectively control and reduce the head imprint of the IF steel coil with a thickness of ≤3.0 mm, and can still play an effective role even under the condition of no step control, which is convenient to operate and greatly improves the production efficiency.

[0014] In some embodiments, the reference pressure value is 100 KN.

[0015] In some embodiments, the thickness of the steel coil is ≤3.0 mm.

[0016] In some embodiments, the preset temperature is 600-700℃.

[0017] In some embodiments, the cooling treatment package adopts laminar flow cooling.

[0018] In some embodiments, the front stage of the laminar flow cooling adopts concentrated cooling mode, and the rear stage adopts air cooling.

[0019] In some embodiments, the outlet temperature of the rolling treatment is 870℃-1000℃.

[0020] In some embodiments, the components of the interstitial-free steel include, in percent by mass, 0-0.009% C, 0-0.15% Cr, 0-0.09% Si, 0.03%-0.5% Mn, P≤0.02%, S≤0.005%, 0.03%-0.5% Al, N≤0.005%, 0.02%-0.09% Ti, 0-0.009% B, and the balance Fe.

[0021] In some embodiments, during the coiling, no step control is performed.

[0022] In a second aspect of the present application, there is provided an interstitial-free steel coil produced by the method of controlling the imprint of the head of a hot-rolled interstitial-free steel according to the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A photograph of an interstitial-free steel coil produced for Example 1;

[0024] Figure 2 A photograph of an interstitial-free steel coil produced for Comparative Example 1;

[0025] Figure 3 A photograph of an interstitial-free steel coil produced for Comparative Example 2;

[0026] Figure 4 A photograph of an interstitial-free steel coil produced for Comparative Example 3. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present application, a more complete description of the present application will be provided below, and a preferred embodiment of the present application will be provided. However, the present application can be implemented in many different forms, and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the specification herein is only for the purpose of describing the specific embodiments of the present application, and is not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0029] In the description of the embodiments of the present application, the technical terms "first", "second", and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0030] "RANGES" disclosed herein can be defined with both a lower and an upper limit and a given range is defined by selecting a lower limit and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges defined in this manner can be either inclusive or exclusive of the end values, either end value can be included or excluded independently, and can be combined in any manner, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Further, if a minimum range value of 1 and 2 are listed, and if a maximum range value of 3, 4, and 5 are also listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise indicated, a numerical range "a-b" indicates a shorthand way of describing each and every intervening real number, integer or combination of integers between the upper and lower limits of that range, in which "a" and "b" are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, "0-5" is merely a shorthand way of describing these numerical combinations. In addition, when a parameter is stated to be an integer ≥ 2, it is equivalent to listing the parameter as, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is stated to be an integer selected from "2-10", it is equivalent to listing the integer 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0031] In this application, "optionally," "optional," or "optional" means optional, i.e., selected from the group consisting of "present" or "absent." If there are multiple "optionally" in a technical solution, each "optionally" is independent of each other, unless otherwise specified, and there is no contradiction or mutual restriction.

[0032] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive or alternative embodiments. It is expressly understood that the embodiments described herein are combinable.

[0033] In the conventional technology, the head part needs to be kept tightly wound during the winding process and cannot be unwound, which results in the inability to effectively control the head part impression. In the conventional technology, only the conventional coiler roller step control is used, which can reduce the pressure of the coiler roller, but the control of the head part impression is limited, and the head part impression of the IF steel coil with a thickness ≤ 3.0 mm cannot be effectively controlled.

[0034] The applicant found that the cooling coiling temperature after rolling has an effect on the yield strength of the steel strip during coiling, and the response speed of the coiler equipment has an effect on controlling the head tongue imprint of the steel coil. The head tongue imprint of the steel coil is formed due to the fact that the head of the steel strip is pressed by the un-timely opening of the coiler roll during coiling, and the stress of the steel coil exceeds the yield limit.

[0035] Therefore, the technical solution of the present application is obtained after a large number of experiments, and the researchers creatively propose the method for controlling the head imprint of the hot-rolled interstitial-free steel in the present application.

[0036] An embodiment of the present application provides a method for controlling the head imprint of the hot-rolled interstitial-free steel, which comprises the following steps:

[0037] The slab of the interstitial-free steel after the rolling treatment is subjected to a cooling treatment, and then is coiled at a preset temperature by using a three-roll coiler to obtain a steel coil.

[0038] During the coiling process, the coiling temperature of the head region of the slab with a length of 20 m is lower than the preset temperature by 30℃, and before the coiler roll is fully opened, the pressure control is performed at the position control, and the following procedures are performed:

[0039] When the actual value of the head pressure of the coiler roll is greater than the reference pressure value, the KP value of the oil cylinder servo valve of the coiler roll WR1 is set to 20, the KP value of the oil cylinder servo valve of the coiler roll WR2 is set to 22, and the KP value of the oil cylinder servo valve of the coiler roll WR3 is set to 24.

[0040] When the actual value of the head pressure of the coiler roll is less than or equal to the reference pressure value, the KP value of the oil cylinder servo valve of the coiler roll WR1 is set to 16, the KP value of the oil cylinder servo valve of the coiler roll WR2 is set to 18, and the KP value of the oil cylinder servo valve of the coiler roll WR3 is set to 20.

[0041] The applicant found that the cooling coiling temperature after rolling has an effect on the yield strength of the steel strip during coiling, and the response speed of the coiler equipment has an effect on controlling the head tongue imprint of the steel coil. The head tongue imprint of the steel coil is formed due to the fact that the head of the steel strip is pressed by the un-timely opening of the coiler roll during coiling, and the stress of the steel coil exceeds the yield limit.

[0042] Therefore, the application creatively proposes to improve the head yield strength by reducing the head coiling temperature, thereby affecting the pressure on the coiler's helping roll, and further setting the servo valve response speed coefficient KP value of the helping roll cylinder when the position control is converted to the pressure control, that is, when the pressure is greater than the reference pressure value, the servo valve KP value of the cylinder is controlled to quickly open the helping roll, and when the pressure is less than or equal to the reference pressure value, the servo valve KP value of the cylinder is controlled to open the helping roll at an appropriate speed, so as to solve the problem of head tongue imprint caused by slow response of the position control to the pressure control before the helping roll is completely opened. After a large number of experiments, the technical scheme of the application is obtained.

[0043] Further, the above method of controlling the head imprint of the hot-rolled head of the interstitial-free steel can also effectively control the head imprint of the IF steel coil with a thickness of ≤3.0 mm, and can still play an effective role even under the condition of no step control, which is easy to operate and greatly improves the production efficiency.

[0044] It can be understood that the preset temperature during coiling is the commonly used coiling temperature of interstitial-free steel, which can be selected according to the model of the interstitial-free steel; the head region of 20m long located at the head of the slab refers to a head region formed by extending 20m long in a straight line from the starting point of the head end position of the slab to the direction away from the head end.

[0045] It should be noted that the three-roll coiler includes three helping rolls: the helping roll WR1, the helping roll WR2, and the helping roll WR3, which are all conventional knowledge in the field, and the servo valve KP value of the helping roll WR1, the helping roll WR2, and the helping roll WR3 can be pre-set through the program.

[0046] Specifically, the method for controlling the head imprint of the hot-rolled head of the interstitial-free steel includes the following steps:

[0047] S1: loading the cooled slab through the pinch roll of the three-roll coiler; S2: changing the position control of the coiler roll loading to pressure control; S3: when the coiling length position of the slab reaches the head region of 20m long of the slab head, triggering the coiler roll to change from pressure control to position control before fully opening; S41: when the actual value of the head pressure of the coiler roll is greater than the preset reference pressure value, setting S42 as follows: setting the KP value of the oil cylinder servo valve of the coiler roll WR1 to 20, the KP value of the oil cylinder servo valve of the coiler roll WR2 to 22, and the KP value of the oil cylinder servo valve of the coiler roll WR3 to 24, so as to quickly open the coiler roll; S51: when the actual value of the head pressure of the coiler roll is less than or equal to the preset reference pressure value, setting S52 as follows: setting the KP value of the oil cylinder servo valve of the coiler roll WR1 to 16, the KP value of the oil cylinder servo valve of the coiler roll WR2 to 18, and the KP value of the oil cylinder servo valve of the coiler roll WR3 to 20; in this way, the coiler roll is opened at a normal speed, and finally S6: the coiler roll is fully opened and separated from the steel strip, realizing coiling while not causing head tongue pressure.

[0048] In some embodiments, the reference pressure value is 100 KN.

[0049] In some embodiments, the thickness of the steel coil is ≤3.0 mm.

[0050] In some embodiments, the preset temperature is 600-700℃.

[0051] In some embodiments, the cooling treatment package adopts laminar flow cooling.

[0052] In some embodiments, the front section of the laminar flow cooling adopts concentrated cooling mode, and the rear section adopts air cooling.

[0053] It can be understood that by pre-setting the conditions of the laminar flow cooling, the temperature of each part of the slab can be controlled, so as to control the temperature during coiling.

[0054] In some embodiments, the outlet temperature of the rolling treatment is 870℃-1000℃.

[0055] The interstitial-free steel can be each type of interstitial-free steel known in the art.

[0056] In some embodiments, according to the mass percentage, the composition of the interstitial-free steel includes: 0-0.009% C, 0-0.15% Cr, 0-0.09% Si, 0.03%-0.5% Mn, P≤0.02%, S≤0.005%, 0.03%-0.5% Alt, N≤0.005%, 0.02%-0.09% Ti, 0-0.009% B, and the balance of Fe.

[0057] In some embodiments, the composition of the interstitial-free steel, in terms of percentage by mass, comprises: 0.001% to 0.009% C, 0.001% to 0.15% Cr, 0.001% to 0.09% Si, 0.03% to 0.5% Mn, 0≤P≤0.02%, 0≤S≤0.005%, 0.03% to 0.5% Alt, N≤0.005%, 0.02% to 0.09% Ti, 0 to 0.009% B, and the balance of Fe.

[0058] It can be understood that "Alt" is acid-soluble aluminum.

[0059] In some embodiments, no step control is performed during coiling.

[0060] Another embodiment of the present application provides an interstitial-free steel coil, which is made by the method for controlling head imprint of hot-rolled interstitial-free steel according to the first aspect.

[0061] The above method can produce a steel coil with no head imprint and perfect performance.

[0062] The present application will be described in detail below with reference to specific embodiments, but the present application is not limited to the following embodiments. It should be understood that the appended claims define the scope of the present application, and those skilled in the art should realize that certain changes to the embodiments of the present application will be covered by the spirit and scope of the claims.

[0063] The following are specific embodiments.

[0064] Embodiment 1

[0065] (1) A conventional interstitial steel slab is selected, and the slab is rolled using a hot continuous rolling mill set, with the control of the finish rolling exit temperature being 870-1000°C, and then entering laminar cooling: using a front concentrated cooling mode and a rear regional air cooling mode to control the coiling temperature to be 600°C, and the head 20m coiling temperature to be 570°C, entering a three-roll coiler for coiling, before the full opening of the coiling aid roll, the head pressure of the coiling aid roll is greater than 100KN during the pressure control and position control, the settings are: the KP value of the oil cylinder servo valve of the coiling aid roll WR1 is 20, the KP value of the oil cylinder servo valve of the coiling aid roll WR2 is 22, and the KP value of the oil cylinder servo valve of the coiling aid roll WR3 is 24, the coiling aid roll is opened quickly until the coiling aid roll is fully opened and separated from the steel strip, and a steel coil with a thickness of 3.0mm is obtained.

[0066] The physical map of the steel coil is shown in Figure 1 , and the head has no tongue imprint.

[0067] Embodiment 2

[0068] Example 2 is basically the same as Example 1, except that (1) another different type of gapless atomic steel slab is selected, the actual value of the head pressure of the winding roll is less than 100 KN, and the settings are: the KP value of the oil cylinder servo valve of the winding roll WR1 is 16, the KP value of the oil cylinder servo valve of the winding roll WR2 is 18, and the KP value of the oil cylinder servo valve of the winding roll WR3 is 20, until the winding roll is completely opened and separated from the steel strip, and a steel coil with a thickness of 3.0 mm is obtained.

[0069] The other steps are the same as in Example 1. There is no tongue imprint at the head of the steel coil.

[0070] Comparative Example 1

[0071] Comparative Example 1 is basically the same as Example 1, except that the KP value of the oil cylinder servo valve of the winding roll WR1 is 16, the KP value of the oil cylinder servo valve of the winding roll WR2 is 18, and the KP value of the oil cylinder servo valve of the winding roll WR3 is 20.

[0072] The other steps are the same as in Example 1. There is a clear tongue imprint at the head of the steel coil, and a physical diagram is shown in Figure 2 .

[0073] Comparative Example 2

[0074] Comparative Example 2 is basically the same as Example 1, except that the head 20 m coiling temperature is also 600°C.

[0075] The other steps are the same as in Example 1. There is a clear tongue imprint at the head of the steel coil, and a physical diagram is shown in Figure 3 .

[0076] Comparative Example 3

[0077] Comparative Example 3 is basically the same as Comparative Example 1, except that the head 20 m coiling temperature is also 600°C.

[0078] The other steps are the same as in Comparative Example 1. There is a more obvious tongue imprint at the head of the steel coil than in Comparative Example 1, and a physical diagram is shown in Figure 4 .

[0079] Comparative Example 4

[0080] Comparative Example 4 is basically the same as Example 2, except that the head 20 m coiling temperature is also 600°C.

[0081] The other steps are the same as in Example 1. There is a slight tongue imprint at the head of the steel coil.

[0082] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, it is to be understood that the application encompasses all such possible combinations.

[0083] The above embodiments only express several implementation manners of the application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent application scope. It should be pointed out that for ordinary skilled persons in the art, some modifications and improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application. Therefore, the protection scope of the patent should be subject to the appended claims.

Claims

1. A method of controlling the imprint of the head of a hot-rolled gapless atomic steel, characterized in that, The method comprises the following steps: cooling a slab of gapless atomic steel after rolling treatment, and then coiling the slab at a preset temperature by using a three-roll coiler to obtain a steel coil; during the coiling process, the coiling temperature of a head region of the slab with a length of 20 m at the head is 30 DEG C lower than the preset temperature, and before the full opening of a coiling roll of the three-roll coiler, pressure control is performed according to the following flow: when the actual value of the head pressure of the coiling roll is greater than a reference pressure value, the KP value of a cylinder servo valve of the coiling roll WR1 is set to 20, the KP value of a cylinder servo valve of the coiling roll WR2 is set to 22, and the KP value of a cylinder servo valve of the coiling roll WR3 is set to 24; when the actual value of the head pressure of the coiling roll is less than or equal to the reference pressure value, the KP value of a cylinder servo valve of the coiling roll WR1 is set to 16, the KP value of a cylinder servo valve of the coiling roll WR2 is set to 18, and the KP value of a cylinder servo valve of the coiling roll WR3 is set to 20. The reference pressure value is 100 KN, and the preset temperature is 600-700 DEG C.

2. The method of controlling the head print of a gapless atomic steel hot rolled head as claimed in claim 1, characterized in that, The cooling treatment adopts laminar cooling.

3. The method of controlling the head print of a gapless atomic steel hot rolled head as claimed in claim 2, characterized in that, The laminar cooling adopts a concentrated cooling mode in the front stage and an air cooling mode in the rear stage.

4. Method of controlling the head print of a hot rolled head of a gapless atomic steel according to any one of claims 1 to 3, characterized in that, The outlet temperature of the rolling treatment is 870 DEG C-1000 DEG C.

5. A method of controlling the head print of a hot rolled head of a gapless atomic steel according to any one of claims 1 to 3, characterized in that, The components of the gapless atomic steel, in terms of mass percentage, comprise 0.001%-0.009% C, 0.001%-0.15% Cr, 0.001%-0.09% Si, 0.03%-0.5% Mn, 0≤P≤0.02%, 0≤S≤0.005%, 0.03%-0.5% Alt, N≤0.005%, 0.02%-0.09% Ti, 0-0.009% B, and the balance of Fe.

6. A method of controlling head stamping of a hot rolled head of a gapless atomic steel according to any one of claims 1 to 3, characterized in that, During the coiling process, no step control is performed.

7. A gap-free atomic steel coil, characterized in that, The method is prepared by using the method for controlling the head imprint of hot rolling of gapless atomic steel according to any one of claims 1-6.

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