JP2018153843A - Rolling method of steel plate and manufacturing method of steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling method of a steel plate capable of performing rolling with such a rolling schedule that the total rolling time becomes minimum, and to provide a manufacturing method of the steel plate.SOLUTION: Several patterns of rolling schedules in a first rolling process are prepared, a rolling time in the first rolling process is calculated and, at the same time, a cooling time of a steel plate on an intermediate cooling process is calculated on the basis of a plate thickness upon first rolling process completion on each of the several patterns of rolling schedules. Further, by using the plate thickness upon the first rolling process completion on each of the several patterns of the rolling schedules after cooling completion of the steel plate on the intermediate cooling process, rolling schedules in a second rolling process are prepared and a rolling time on the second rolling process is calculated. Therein, the rolling time on the first rolling process, the cooling time on the intermediate cooling process and the rolling time on the second rolling process are summed up, such a rolling schedule that the total rolling time becomes minimum is led out and manufacturing conditions corresponding to the plate thickness upon the first rolling process completion which provides the rolling schedule are determined.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for rolling a steel plate and a method for producing a steel plate.

  Conventionally, controlled rolling is known as one of the manufacturing techniques of a steel plate excellent in strength and toughness. This is a state in which a steel material such as a slab heated in a heating furnace is once rolled to a predetermined intermediate plate thickness, and then the temperature of the material to be rolled is in the non-recrystallization temperature range or a temperature range in the vicinity thereof. The rolling is performed up to the finished sheet thickness. For the purpose of shortening the waiting time for the material to be rolled, which has reached the intermediate plate thickness, to cool down to a predetermined finish rolling start temperature, a cooling device is provided upstream or downstream of the rolling mill, or an existing scale breaker is installed. Techniques have been proposed such as utilizing the descaling water to cool a material to be rolled with an intermediate thickness (Patent Document 1, Patent Document 2, etc.).

  On the other hand, a first rolling mill that performs hot rolling from a steel material such as a slab to an intermediate thickness, and a second rolling mill that performs hot rolling from an intermediate thickness to a finished thickness, There is also known a technique for improving manufacturing efficiency by providing the above. Thus, even in a rolling line equipped with two rolling mills, by providing an intermediate cooling device in the vicinity of the rolling mill, for example, between the first rolling mill and the second rolling mill, The time for cooling the material to be rolled, which has been rolled to a predetermined intermediate sheet thickness by the first rolling mill, to a predetermined finish rolling start temperature in the second rolling mill can be shortened. Here, if the cumulative rolling reduction in the second rolling mill is equal to or greater than a predetermined value determined according to the steel component and the desired strength / toughness level, the intermediate to be achieved in the first rolling mill. There is often a slight degree of freedom in the plate thickness.

JP 2005-00979 A JP 2009-28747 A

  As described above, in the rolling line provided with the first rolling mill, the second rolling mill, and the intermediate cooling device, in the rolling pass schedule in the hot rolling process, in the second rolling mill The thickness of the material to be rolled conveyed from the first rolling mill to the intermediate cooling device within the range in which the cumulative rolling reduction can ensure the predetermined value, in other words, the number of rolling passes for completing the rolling in the first rolling mill. May be adjusted by the operator. In particular, as a large judgment material for determining the number of rolling passes, whether or not the second rolling mill is rolling is a big judgment material. That is, when the second rolling mill has completed the rolling of the preceding material to be rolled and the second rolling mill is in an empty state that is not rolling, or soon the second rolling mill Is in an empty state, the operator forcibly ends the rolling of the material to be rolled by the first rolling mill, and the material to be rolled by the first rolling mill is transferred to the intermediate cooling device. It is conveyed and cooling by the intermediate cooling device is started. Thereafter, the material to be rolled that has been cooled by the intermediate cooling device is conveyed to a second rolling mill that is in an empty state, and rolling of the material to be rolled by the second rolling mill is started.

  In such a rolling method, at first glance, the rolling time of the material to be rolled by the first rolling mill, the cooling time of the rolled material by the intermediate cooling device, and the rolling time of the rolled material by the second rolling mill It seems that the total rolling time, which is the sum of the above, is minimized, but in reality, the length of the cooling time in the intermediate cooling device is not taken into consideration, and therefore the total rolling time may not be minimized. That is, the operator determines that the second rolling mill is in an empty state, or that the second rolling mill will be in an empty state soon, and the number of rolling passes is less than the original number of rolling passes. When rolling by the first rolling mill is finished and the material to be rolled is transported to the intermediate cooling device, rolling is performed with the original number of rolling passes and then the material to be rolled is transported to the intermediate cooling device. However, the material to be rolled is cooled in a state where the plate thickness is thick. Therefore, the cooling efficiency in the intermediate cooling device becomes very poor. As a result, the cooling time in the intermediate cooling device becomes long, so that the second rolling from the rolling start time of the first rolling mill. The total rolling time, which is the elapsed time until the rolling end time of the machine, is not necessarily minimized.

  The present invention has been made in view of the above problems, and its purpose is to provide a rolling method of a steel sheet that can be rolled with a rolling pass schedule that minimizes the total rolling time, and a manufacturing method of the steel sheet. It is to be.

  In order to solve the above-described problems and achieve the object, the rolling method of the steel sheet according to the present invention includes a first rolling process for performing rolling of one pass or more, an intermediate cooling process, and rolling of one or more passes. In the rolling method of the steel sheet to carry out the second rolling step in this order, a plurality of candidate values for the first rolling end plate thickness that is the plate thickness of the steel plate at the end of the first rolling step are set in advance, A first rolling condition calculation step for calculating a rolling condition for realizing a candidate value of the first rolling end plate thickness with respect to each of the candidate values, and obtaining a time required for the first rolling process, and a plurality of first rolling An intermediate cooling condition is calculated for each of the end plate thickness candidate values, and an intermediate cooling condition calculating step for obtaining a time required for the intermediate cooling step, and a plurality of first rolling end plate thickness candidate values, respectively. When the calculated intermediate cooling conditions are adopted About the second rolling condition calculation step for calculating the rolling condition of the second rolling step and obtaining the required time of the second rolling step, and the plurality of candidate values for the first rolling end plate thickness, The time required for the first rolling process obtained in the rolling condition calculation step, the time required for the intermediate cooling process obtained in the intermediate cooling condition calculation step, and the second rolling condition calculation step. A total required time calculating step for calculating a total required time that is a sum of the required times for the second rolling process, and a plurality of the total required times calculated for a plurality of candidate values for the first rolling end plate thickness. Of the time, the first rolling end plate thickness candidate value selection step for selecting the first rolling end plate thickness candidate value that gives the minimum total required time, and the first rolling end plate thickness candidate value selection step are selected. End of the first rolling A manufacturing condition determination step for determining the rolling condition of the first rolling process, the intermediate cooling condition, and the rolling condition of the second rolling process as manufacturing conditions, which are calculated for the thickness candidate value. It is a feature.

  Further, the steel sheet rolling method according to the present invention is characterized in that, in the above invention, the first rolling step and the second rolling step are performed by different rolling mills.

  The steel sheet rolling method according to the present invention is characterized in that, in the above invention, the first rolling step and the second rolling step are carried out by the same rolling mill.

  Moreover, the manufacturing method of the steel plate which concerns on this invention manufactures a steel plate using the rolling method of the steel plate of said invention, It is characterized by the above-mentioned.

  The rolling method of a steel plate and the manufacturing method of a steel plate according to the present invention have an effect that rolling can be performed with a rolling schedule that minimizes the total rolling time.

FIG. 1 is a schematic diagram illustrating an example of a steel sheet production line to which the steel sheet rolling method and the steel sheet manufacturing method according to the present embodiment are applied. FIG. 2 is a flowchart illustrating an example of a control flow executed by the process computer. FIG. 3 is a flowchart showing an example of the first rolling condition calculation step. FIG. 4 is a flowchart showing an example of the intermediate cooling condition calculation step. FIG. 5 is a flowchart showing an example of the second rolling condition calculation step. FIG. 6 is a flowchart showing an example of the total required time calculation step. FIG. 7 is a flowchart showing an example of the first rolling end plate thickness candidate value selection step. FIG. 8 is a flowchart showing an example of the manufacturing condition determination step.

  Below, one Embodiment of the rolling method of the steel plate which concerns on this invention, and the manufacturing method of a steel plate is described. In addition, this invention is not limited by this embodiment.

  FIG. 1 is a schematic diagram illustrating an example of a steel sheet production line to which the steel sheet rolling method and the steel sheet manufacturing method according to the present embodiment are applied. In the steel plate production line according to the present embodiment, a steel plate (specifically, a thick steel plate) is produced from the slab, and as shown in FIG. 1, it can be controlled by each device constituting the steel plate production line. A connected process computer 1, a heating furnace 2 for heating the rolled material W, a transport roll 3 for transporting the rolled material W extracted from the heating furnace 2, a first rolling mill 4 used in the first rolling step, 1st cooling device 5 which cools rolling material W after the 1st rolling process, 2nd rolling machine 6 used at the 2nd rolling process, and 1st straightening machine which corrects distortion of rolling material W after the 2nd rolling process 7, a second cooling device 8 for cooling the rolled material W whose distortion has been corrected by the first straightening machine 7, and a second straightening device 9 for correcting the distortion of the rolled material W cooled by the second cooling device 8 It has. In the following description, the slab before rolling and the steel plate after rolling are collectively defined as a rolled material W.

  In the steel sheet production line according to the present embodiment, as will be described later, the process computer 1 calculates and determines the rolling pass schedule and production conditions of the rolled material W, thereby rolling time in the first rolling step. It is possible to perform rolling with a rolling pass schedule that minimizes the total rolling time in the entire rolling line, not the shortest time of the cooling time in the intermediate cooling process and the rolling time in the second rolling process. .

  That is, a process computer is used to perform controlled rolling in a hot rolling process in a steel sheet production line having the first rolling mill 4 and the second rolling mill 6 and the first cooling device 5 disposed therebetween. 1, the rolling pass schedules in the first rolling mill 4 and the second rolling mill 6 are calculated. In performing this calculation, the rolling mill is used to calculate the rolling pass schedule for rolling the rolled material W from the plate thickness X to the plate thickness Y. Further, by using the cooling model, the first cooling device 5 is allowed to calculate the time required for cooling the temperature of the rolled material W having the thickness Y from the temperature A to the temperature B. Further, the second rolling mill 6 is caused to calculate a rolling pass schedule for rolling the rolled material W from the plate thickness Y to the plate thickness Z that is the target plate thickness of the product. Then, the total rolling time is derived by adding these calculation results, and the one with the minimum total rolling time is displayed on a monitor or the like and notified to the operator.

  In addition, the calculation of the rolling pass schedule by the process computer 1 sets the processing timing so that the calculation can be performed at the timing when the slab to be rolled is extracted from the heating furnace 2. In addition, it is desirable that the machine specifications of the process computer 1 be high so that the calculation of the rolling pass schedule is completed in a very short time.

  Hereinafter, an example of a control flow such as a rolling pass schedule calculation process and a manufacturing condition determination process executed by the process computer 1 will be described in detail with reference to the flowcharts shown in FIGS.

  FIG. 2 is a flowchart illustrating an example of a control flow executed by the process computer 1. The hot rolling process performed in the production line of the steel sheet according to the present embodiment includes a first rolling process that performs rolling of one or more passes, an intermediate cooling process, and a second rolling process that performs rolling of one or more passes. Are performed in this order. And in implementing such a hot rolling process, as shown in FIG. 2, the first rolling condition calculation step S1, the intermediate cooling condition calculation step S2, the second rolling condition calculation step S3, and the total required time A rolling path that minimizes the total rolling time by the process computer 1 executing a control flow comprising the calculation step S4, the first rolling end thickness candidate value selection step S5, and the production condition determination step S6. A schedule and manufacturing conditions at that time are obtained.

  FIG. 3 is a flowchart showing an example of the first rolling condition calculation step S1. Table 1 shows examples of various parameters in the first rolling process.

In the first rolling condition calculation step S1, first, candidate values for a preset N-level first rolling finished sheet thickness t ₁ (i) (where i = 1 to N) are acquired (S11). The candidate value of the first rolling finished sheet thickness t ₁ (i) can be determined based on past manufacturing results and experience.

Next, in the first rolling step, as the rolling condition (rolling schedule) for obtaining the first rolling finished sheet thickness t ₁ (i), for example, the number of passes n ₁ (i) and the reduction amount R _n1 ( i) and the like are calculated (S12). A known rolling model can be used for this calculation. In addition, it is possible to refer to past production results tabulated, and to calculate values obtained by further interpolation / extrapolation.

Next, as the rolling condition (rolling schedule) corresponding to the N-level first rolling finished sheet thickness t ₁ (i), for example, {number of passes n ₁ (i), reduction amount R _n1 (i): , I = 1 to N} N sets of rolling conditions are obtained (S13). At the same time, the plate size at the end of the first rolling is {plate thickness t ₁ (i), plate width w ₁ (i), plate length L ₁ (i): where i = 1 to N}. A set value is obtained (S14). Further, an N level value is calculated for the required time P ₁ (i) of the first rolling process constituted by a plurality of passes, corresponding to the N level first rolling finished sheet thickness t ₁ (i) (S15). .

Finally, the temperature drop of the rolled material W in the first rolling step is also calculated at the same time, and corresponds to the N-level first rolling end plate thickness t ₁ (i) and the N-level first rolling end temperature T _1f (i ) Is calculated (S16). In addition, about the temperature fall of the rolling material W in a 1st rolling process, it can calculate using a known model formula etc.

  FIG. 4 is a flowchart showing an example of the intermediate cooling condition calculation step S2. Table 2 shows an example of various parameters in the intermediate cooling process.

In the intermediate cooling condition calculation step S2, first, preconditions for calculating the intermediate cooling condition are acquired (S21). In the intermediate cooling step, the plate size information at the end of the first rolling is {plate thickness t ₁ (i), plate width w ₁ (i), plate length L ₁ (i): where i = 1 to N } And {first rolling end temperature T _1f (i), intermediate cooling start temperature T _cs (i): where i = 1 to N} is a precondition for the calculation of the intermediate cooling condition.

Next, it is determined whether the cooling conditions in the intermediate cooling step, such as the cooling capacity (water amount, etc.) C of the first cooling device 5 and the rolling material conveyance speed V, are constant (S22). When the cooling condition is constant (YES in S22), the required time Pc (i) of the N-level intermediate cooling process is calculated corresponding to the N-level first rolling finished sheet thickness t ₁ (i) ( S23). On the other hand, when the cooling condition is changed corresponding to the first rolling end plate thickness t ₁ (i) (NO in S22), for example, {cooling capacity C (i), rolled material conveyance speed V (i): However, the required time P _c (i) of the intermediate cooling process is calculated on the premise of N sets of cooling conditions of i = 1 to N} (S24).

  FIG. 5 is a flowchart showing an example of the second rolling condition calculation step S3. Table 3 shows an example of various parameters in the second rolling process.

In the second rolling condition calculation step S3, first, a precondition for calculating the second rolling condition is acquired (S31). In the second rolling step, the plate size information at the end of the intermediate cooling is {plate thickness t ₁ (i), plate width w ₁ (i), plate length L ₁ (i): where i = 1 to N } And {intermediate cooling end temperature T _cf (i), second rolling start temperature T _2s (i): where i = 1 to N} is a precondition for the calculation of the second rolling condition.

Next, in the second rolling step, rolling conditions (rolling) for obtaining the second rolling end thickness t ₂ (i) which is a common value regardless of the N-level first rolling end thickness t ₁ (i). As the schedule, for example, the number of passes n ₂ (i) and the reduction amount R _n2 (i) in each pass are calculated for the N level (S32). A known rolling model can be used for this calculation. In addition, it is possible to refer to past production results tabulated, and to calculate values obtained by further interpolation / extrapolation.

Next, as the rolling condition (rolling schedule) corresponding to the N-level second rolling finished sheet thickness t ₂ (i), for example, {number of passes n ₂ (i), reduction amount R _n2 (i): , I = 1 to N} N sets of rolling conditions are obtained (S33). At the same time, as the plate size at the end of the second rolling, {plate thickness t ₂ (i), plate width w ₂ (i), plate length L ₂ (i): where N = 1 to N} Is obtained (S34). Further, an N level value is calculated for the required time P ₂ (i) of the second rolling process constituted by a plurality of passes, corresponding to the N level second rolling end sheet thickness t ₂ (i) (S35). .

Finally, the temperature drop of the rolled material W in the second rolling step is also calculated at the same time, corresponding to the N-level second rolling end plate thickness t ₂ (i), and the N-level second rolling end temperature T _2f (i ) Is calculated (S36). In addition, about the temperature fall of the rolling material W in a 2nd rolling process, it can calculate using a known model formula etc.

FIG. 6 is a flowchart showing an example of the total required time calculation step S4. In the total required time calculating step S4, the required time P ₁ (i) of the first rolling process calculated in the first rolling condition calculating step S1, and the required time P _c of the intermediate cooling process calculated in the intermediate cooling condition calculating step S2. Based on the required time P ₂ (i) of the second rolling process calculated in (i) and the second rolling condition calculation step S3, as shown by the following formula (1), The required time P _total (i) is set to i = 1 to N, that is, corresponding to each of the preset N-level first rolling end sheet thickness t (i) (where i = 1 to N). Calculate (S41).

FIG. 7 is a flowchart showing an example of the first rolling end plate thickness candidate value selection step S5. In the first rolling end plate thickness candidate value selection step S5, the total required time P _total (i) corresponding to each of the preset N level first rolling end plate thicknesses t ₁ (i) (i = 1 to N). ) (I = 1 to N) are compared, and the first rolling finish sheet thickness t ₁ (k) (1 ≦ k ≦ N) that gives the minimum total required time P _total (i) is selected (S51).

FIG. 8 is a flowchart showing an example of the manufacturing condition determination step S6. In the production condition determination step S6, first, it corresponds to the first rolling end plate thickness t ₁ (k) which gives the minimum total required time P _total (i) selected in the first rolling end plate thickness candidate value selection step S5. Manufacturing in which the number of passes n ₁ (k), the reduction amount R _n1 (k), the number of passes n ₂ (k), the reduction amount R _n2 (k), and the like are applied to the rolling material W to be rolled. The condition is determined (S61).

Next, it is determined whether or not the intermediate cooling conditions such as the cooling capacity C and the rolling material conveyance speed V are changed for every N-level first rolling finished sheet thickness t ₁ (i) (S62). In this determination, the determination result obtained in the process of S22 in the intermediate cooling condition calculation step S2 may be used. When the intermediate cooling condition is changed for each N-level first rolling end sheet thickness t ₁ (i) (YES in S62), the first rolling end sheet thickness giving the minimum total required time P _total (i) It is determined to use each cooling condition corresponding to t ₁ (k) (S63). On the other hand, when the intermediate cooling condition is not changed for each N-level first rolling finished sheet thickness t ₁ (i) (NO in S62), it is determined to use a predetermined constant cooling condition (S64). ).

  Then, according to the manufacturing conditions determined in the manufacturing condition determination step S6, information necessary for carrying out the first rolling process, the intermediate cooling process, and the second rolling process, for example, on the monitor or terminal of the cab Display and notify the operator. The operator performs operations according to the information displayed on the monitor or terminal. Moreover, you may make it implement a 1st rolling process, an intermediate | middle cooling process, and a 2nd rolling process automatically according to the manufacturing conditions determined by manufacturing condition determination step S6.

As described above, in this embodiment, several patterns are created for the rolling pass schedule in the first rolling process using the first rolling mill 4 that is the first rolling mill, and the rolling time in the first rolling process is set as follows. While calculating, based on the plate | board thickness at the time of completion | finish of the 1st rolling in each rolling pass schedule of several patterns, the cooling time of the rolling material W in the intermediate | middle cooling process which cools the rolling material W with the 1st cooling device 5 is set. calculate. Further, after the cooling of the rolled material W in the intermediate cooling process, the rolling pass in the second rolling process using the second rolling mill 6 which is the second rolling mill using the plate thickness at the end of the first rolling. A schedule is created and the rolling time in the second rolling process is calculated. The rolling time in the first rolling process (required time P ₁ (i)), the cooling time in the intermediate cooling process (required time Pc (i)), and the rolling time in the second rolling process (required time P ₂ (i)) are added together to derive a rolling pass schedule that minimizes the total rolling time (total required time P _total (i)). Also, the rolling schedule that minimizes the total rolling time (total required time) derived in this way is displayed on a monitor or the like to notify the operator and recognize it.

  Thereby, while being able to derive | lead-out the rolling schedule from which the total rolling time becomes the minimum, let the operator recognize the rolling pass schedule from which the total rolling time becomes the minimum, and the 2nd rolling mill 6 will be in an empty state. However, inadvertent rolling is not finished at the first rolling mill 4, and rolling according to a rolling schedule that minimizes the total rolling time becomes possible.

The preconditions in the hot rolling process are the size of the slab extracted from the heating furnace 2 (slab thickness t _s , slab width w _s , slab length L _s , slab mass m _s ) and product size. It is assumed that the size (plate thickness t ₂ , plate width w ₂ , plate length L ₂ , plate mass m) of the rolled material W after completion of the second rolling step is determined in advance. In addition, of the manufacturing conditions, the second rolling start temperature T _2S and the second rolling end temperature T _2f are limited. This is because the second rolling end temperature T _2f is the most important restriction for carrying out the controlled rolling, and the second rolling end temperature T _2f and the thickness t ₂ at that time are set to the target thickness. Rolling process is set up. As a result, there is a restriction on the second rolling start temperature _T2S .

The extraction temperature T _h of the heating furnace 2 is slab temperature when taking out the slab is given as one of the production conditions. Strictly speaking, the extraction temperature T _h to the first rolling start temperature T _1s , the first rolling end temperature T _1f (i) to the intermediate cooling start temperature T _cs (i), and the intermediate cooling end temperature T _cf (i ) To the second rolling start temperature T _2s (i) each have a temperature difference. In the present embodiment, it is assumed that the temperature differences are constant in order to simplify the description. In addition, you may add the said temperature difference to calculation as a variable as needed.

In addition, among the plate sizes at the end of the first rolling, the factors affecting the “difference in cooling behavior in the intermediate cooling process”, which is focused in the present invention, are mainly the plate thickness t ₁ (i) at the end of the first rolling. It is. Therefore, although the plate width w ₁ (i) and the plate length L ₁ (i) at the end of the first rolling are used for the calculation, as a selection condition of the total required time, the first rolling end plate thickness t _It is sufficient to consider only ₁ (i). Also, the slab mass _ms and the plate mass m may be regarded as basically unchanged.

  As mentioned above, in this embodiment, although the 1st rolling process and the 2nd rolling process were mentioned as an example and what was implemented with the rolling mill (the 1st rolling mill 4 and the 2nd rolling mill 6) explained, Even if the first rolling process and the second rolling process are performed by the same rolling mill (only the first rolling mill 4), the present invention can be applied.

DESCRIPTION OF SYMBOLS 1 Process computer 2 Heating furnace 3 Conveyance roll 4 1st rolling mill 5 1st cooling device 6 2nd rolling mill 7 1st straightening machine 8 2nd cooling device 9 2nd straightening machine

Claims (4)

In the rolling method of the steel sheet, the first rolling step for carrying out rolling for one pass or more, the intermediate cooling step, and the second rolling step for carrying out rolling for one pass or more are performed in this order.
A plurality of candidate values for the first rolling end plate thickness that is the plate thickness of the steel plate at the end of the first rolling step are set in advance,
A rolling condition for realizing each first rolling end sheet thickness candidate value is calculated for each first rolling end sheet thickness candidate value, and a first rolling condition calculating step for obtaining a time required for the first rolling step;
Intermediate cooling condition calculation step for calculating the intermediate cooling condition for each first rolling end sheet thickness candidate value, and obtaining the required time of the intermediate cooling process,
For each first rolling end thickness candidate value, calculate the rolling condition of the second rolling step when the intermediate cooling condition calculated in the intermediate cooling condition calculating step is adopted, and the second rolling step A second rolling condition calculation step for obtaining the required time of
For each first rolling end thickness candidate value, the required time of the first rolling step determined in the first rolling condition calculation step and the intermediate cooling step determined in the intermediate cooling condition calculation step A total required time calculating step for calculating a total required time that is a sum of the required time for the second rolling process calculated in the second rolling condition calculating step, and
The first rolling end plate thickness for selecting the first rolling end plate thickness candidate value that gives the minimum total required time among the plurality of total required times calculated for each first rolling end plate thickness candidate value A candidate value selection step;
The rolling condition of the first rolling step, the intermediate cooling condition, and the second rolling step, calculated for the first rolling end plate thickness candidate value selected in the first rolling end plate thickness candidate value selection step. A production condition determining step for determining the rolling conditions as manufacturing conditions,
A method of rolling a steel sheet, comprising: In the rolling method of the steel plate according to claim 1,
The steel sheet rolling method, wherein the first rolling step and the second rolling step are performed by different rolling mills. In the rolling method of the steel plate according to claim 1,
The steel sheet rolling method, wherein the first rolling step and the second rolling step are performed by the same rolling mill.   A method for producing a steel plate, comprising producing a steel plate using the method for rolling a steel plate according to any one of claims 1 to 3.

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