Method for producing pipeline steel plate having improved uniformity

Abstract

Disclosed in the present invention is a method for producing a pipeline steel plate having improved uniformity. The production method comprises: heating a steel slab and rolling the steel slab into a steel plate having a length D; measuring the temperature of the hot-rolled steel plate at points spaced 0.2-0.5 m from head to tail along a longitudinal direction; using the temperatures at the temperature measurement points located in the longitudinal direction within a DT to (D-DW) region to calculate the average temperature TZ in a middle portion; dividing a head low-temperature section having a temperature lower than TZ-TT of the steel plate into first to n-th sub-sections arranged in sequence from the head, and dividing a tail low-temperature section having a temperature lower than TZ-TW of the steel plate into first to m-th sub-sections arranged in sequence from the tail; during a period when the steel plate enters an ultrafast cooling system for water cooling, with the cooling water amount Q per unit length of the middle section as a standard, controlling the cooling water amount per unit length of the first to n-th sub-sections and the cooling water amount per unit length of the first to m-th sub-sections to separately sequentially increase and be less than Q; and then, naturally air-cooling the steel plate to room temperature on a cooling bed to obtain a finished steel plate product.

Description

Production method of pipeline steel plate for improving uniformity

[0001] The present application claims priority to the Chinese patent application with the application date of September 13, 2024, the application number of 202411284989.3, and the invention name of "Production method of pipeline steel plate for improving uniformity", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application belongs to the technical field of steel material preparation, and relates to a production method of steel plate, in particular to a production method of steel plate capable of improving uniformity and used as pipeline steel. BACKGROUND

[0003] Pipeline transportation is one of the five modern transportation modes, together with railway transportation, highway transportation, waterway transportation and air transportation, as a fast, economical and effective mode of oil and natural gas transportation.

[0004] Pipeline steel is a kind of steel with special requirements for pipelines for transporting oil and natural gas, which is rolled into steel plate from billet, and then welded into steel pipe for oil and gas transportation. Due to the harsh application conditions, pipeline steel plate usually needs to have a strict range of tensile strength and yield strength, and also needs to have strict requirements on yield ratio, impact toughness and drop weight tear resistance, so the production is very difficult.

[0005] Especially for pipeline steel applied in harsh service environments such as geography and climate, the mechanical strength level is no longer the most important problem, but the performance uniformity of the steel plate, such as the same plate strength difference and different plate strength difference, is the most serious problem in the production of pipeline steel.

[0006] In the production of existing pipeline steel: a type of technology represented by CN114774658A adopts high Ni, V, Cu and other alloy contents, which can improve the uniformity of the microstructure and performance of the pipeline steel to a certain extent, but increases the production cost; a type of technology represented by CN103993240A adopts a stacking process, which can also improve the uniformity of performance, but the stacking leads to long production time, which is difficult to meet the current requirement of efficient production; and another type of technology represented by CN110343936A solves the problem of improving the difference between horizontal and vertical strength, but cannot improve the uniformity of the performance of the product, such as the same plate strength difference and different plate strength difference.

[0007] In summary, in the field of existing pipeline steel plate, the technology for improving the uniformity of performance (including the same plate strength difference and different plate strength difference) is lacking, and there are problems such as high alloy content and low production efficiency, which restrict the development of the pipeline industry. SUMMARY

[0008] To solve the problems in the prior art, the present application aims to provide a steel plate production method.

[0009] To achieve the above-mentioned application purposes, an embodiment of the present application provides a steel plate production method. The production method comprises:

[0010] heating a billet with a thickness ≤320mm in a heating furnace, after exiting the heating furnace, the billet is firstly rolled in a recrystallization zone and then rolled in a non-recrystallization zone to obtain a hot-rolled steel plate with a longitudinal length D and a thickness t, wherein t is valued at 6-30mm;

[0011] taking points along the longitudinal direction of the hot-rolled steel plate at intervals of 0.2-0.5m from the head to the tail to measure the temperature, and obtaining the temperature measurement results;

[0012] taking the temperature of the temperature measurement points located in the D T -(D-D W ) region in the longitudinal direction to calculate the central average temperature T Z ;

[0013] regarding the head section of the steel plate with a temperature lower than T Z -T T as a head low-temperature section, regarding the tail section of the steel plate with a temperature lower than T Z -T W as a tail low-temperature section, and regarding the remaining sections other than the head low-temperature section and the tail low-temperature section as central sections, wherein T T and T W are each valued at any value in 20-50℃;

[0014] dividing the head low-temperature section into 1st-nth sub-sections arranged in sequence from the head to the low temperature according to the measured temperature, and dividing the tail low-temperature section into 1st-mth sub-sections arranged in sequence from the tail to the low temperature according to the measured temperature, wherein n≥2 and m≥2;

[0015] the hot-rolled steel plate enters a super-fast cooling system for water cooling; during this period, taking the unit length cooling water quantity Q of the central sections as a standard, the unit length cooling water quantity of the 1st-nth sub-sections of the head low-temperature section is controlled to increase in sequence and be less than Q, and the unit length cooling water quantity of the 1st-mth sub-sections of the tail low-temperature section is controlled to increase in sequence and be less than Q;

[0016] after exiting the super-fast cooling system, the steel plate is naturally air-cooled to room temperature on a cooling bed to obtain a steel plate product.

[0017] Preferably, the hot-rolled steel plate has a transverse width W;

[0018] In the step "Temperature measurement is performed at points spaced 0.2 to 0.5 m apart along the longitudinal direction of the hot-rolled steel plate from beginning to end", temperature measurement is performed at points in the W / 3 to 2W / 3 area in the transverse middle of the hot-rolled steel plate, and all temperature measurement points are arranged in a straight line along the longitudinal direction.

[0019] Preferably, step "located longitudinally at D" T ~(DD) W The average temperature T in the central area is calculated by measuring the temperatures at the temperature measurement points within the area. Z "middle:

[0020] Vertically located at D T ~(DD) W The temperatures at the measurement points within the area are summed and averaged to obtain the average temperature T at the center. Z ;

[0021] D T Values ​​range from 1.5 to 3.5 m, D W The value ranges from 1.5 to 3.5 m.

[0022] Preferably, D T and D W The values ​​of decrease stepwise as t increases.

[0023] Preferably, when t < 10 mm, 2.75 m < D T ≤3.5m, 2.75m<D W ≤3.5m;

[0024] When 10mm ≤ t < 15mm, 2.25m < D T ≤2.75m, 2.25m<D W ≤2.75m;

[0025] When 15mm ≤ t ≤ 30mm, 1.5m < D T ≤2.25m, 1.5m<D W ≤2.25m.

[0026] Preferably, the step "lowering the temperature to T" Z -T T The head section of the steel plate is designated as the low-temperature head section, with a temperature lower than T. Z -T W The section at the tail of the steel plate is designated as the tail low-temperature section, and the remaining sections, excluding the head and tail low-temperature sections, are designated as the middle section.

[0027] The head low-temperature section and the middle section are divided by a temperature measuring point; the tail low-temperature section and the middle section are also divided by a temperature measuring point.

[0028] Preferably, the step "lowering the temperature to T"Z -T T The head section of the steel plate is designated as the low-temperature head section, with a temperature lower than T. Z -T W The section at the tail of the steel plate is designated as the tail low-temperature section, and the remaining sections, excluding the head and tail low-temperature sections, are designated as the middle section.

[0029] Starting from the beginning along the longitudinal direction of the steel plate, when the temperature of the temperature measuring point closer to the beginning of the plate is less than T, among two adjacent temperature measuring points, the temperature of the measuring point closer to the beginning of the plate is less than T. Z -T T The temperature at a temperature measuring point far from the plate head reaches T. Z -T T When the above is the case, one of the two adjacent temperature measuring points is used as the dividing line to divide the longitudinally arranged head low temperature section and middle section.

[0030] Starting from the tail end along the longitudinal direction of the steel plate, when the temperature of one of two adjacent temperature measuring points is less than T, Z -T W The temperature at a temperature measuring point far from the tail of the plate reached T. Z -T W In the above cases, one of the two adjacent temperature measurement points is used as the dividing line to divide the longitudinally arranged tail low-temperature section and middle section.

[0031] Preferably, the step "lowering the temperature to T" Z -T T The head section of the steel plate is designated as the low-temperature head section, with a temperature lower than T. Z -T W The section at the tail of the steel plate is designated as the tail low-temperature section, and the remaining sections, excluding the head and tail low-temperature sections, are designated as the middle section.

[0032] Based on the temperature measurement results, the temperature curve of the entire longitudinal length of the steel plate is obtained by fitting temperature as the dependent variable and location as the independent variable.

[0033] Confirm that within the temperature range of 0 to D / 2, T on the temperature curve Z -T T The corresponding position D TF And confirm that within the D / 2 to D interval, the temperature curve at point T... Z -T W The corresponding position D WF ;

[0034] With position D TF and position D WF To define the boundaries, the steel plate is divided into a head low-temperature section, a middle section, and a tail low-temperature section arranged longitudinally from beginning to end.

[0035] Preferably, in the step "dividing the head low-temperature segment into sub-segments arranged sequentially from head to n according to the measured temperature from low to high, and dividing the tail low-temperature segment into sub-segments arranged sequentially from tail to m according to the measured temperature from low to high, where n≥2, m≥2":

[0036] According to the temperature span of each sub-section not exceeding T Tk The low-temperature segment of the head is divided into n sub-segments;

[0037] According to the temperature span of each sub-section not exceeding T Wk The tail section of low temperature is divided into m sub-segments;

[0038] Among them, T Tk The highest temperature T among all temperature measurement points in the low-temperature section of the head. T1 and the lowest temperature range T T0 The difference T T1 -T T0 1 / n, or the highest temperature T in the low-temperature segment of the temperature curve at the head. Z -T T and the lowest temperature range T T0 'difference T' Z -T T -T T0 '1 / n', or a predetermined value T for the temperature span. n ;

[0039] T Wk The highest temperature T among all temperature measurement points in the low-temperature section of the tail section. W1 and the lowest temperature range T W0 The difference T W1 -T W0 1 / m, or the highest temperature T in the low-temperature section of the temperature curve at the tail end. Z -T W and the lowest temperature range T W0 'difference T' Z -T W -T W0 '1 / m, or a predetermined value T for the temperature span. m ;

[0040] The temperature curve was obtained by fitting the temperature curve with temperature as the dependent variable and location as the independent variable based on the temperature measurement results.

[0041] T n and T m Each value is taken from any value between 5 and 20℃.

[0042] Preferably, in the step of "dividing the head low-temperature section into 1st-nth sub-sections arranged in sequence from the head according to the measured temperature from low to high, and dividing the tail low-temperature section into 1st-mth sub-sections arranged in sequence from the tail according to the measured temperature from low to high, n≥2, m≥2":

[0043] In the 1st-nth sub-sections, two adjacent sub-sections are divided by a temperature measuring point.

[0044] In the 1st-mth sub-sections, two adjacent sub-sections are divided by a temperature measuring point.

[0045] Preferably, in the step of "dividing the head low-temperature section into 1st-nth sub-sections arranged in sequence from the head according to the measured temperature from low to high, and dividing the tail low-temperature section into 1st-mth sub-sections arranged in sequence from the tail according to the measured temperature from low to high, n≥2, m≥2":

[0046] Starting from the 1st temperature measuring point close to the head of the head low-temperature section, when the temperature of the temperature measuring point close to the head among two adjacent temperature measuring points is not more than T Tk away from the head than the lowest temperature section of the sub-section, and the temperature of the temperature measuring point away from the head is more than T Tk away from the head than the lowest temperature section of the sub-section, the temperature measuring point close to the head is taken as the division boundary to divide the sub-section and the next sub-section;

[0047] Starting from the 1st temperature measuring point close to the tail of the tail low-temperature section, when the temperature of the temperature measuring point close to the tail among two adjacent temperature measuring points is not more than T Wk away from the tail than the lowest temperature section of the sub-section, and the temperature of the temperature measuring point away from the tail is more than T Wk away from the tail than the lowest temperature section of the sub-section, the temperature measuring point close to the tail is taken as the division boundary to divide the sub-section and the next sub-section.

[0048] Preferably, in the step of "the hot-rolled steel plate enters the ultra-fast cooling system for water cooling, and the final cooling temperature is 210-530℃; during which, taking the unit length cooling water quantity Q of the middle section as the standard, the unit length cooling water quantity of the 1st-nth sub-sections of the head low-temperature section is controlled to increase successively and be less than Q, and the unit length cooling water quantity of the 1st-mth sub-sections of the tail low-temperature section is controlled to increase successively and be less than Q":

[0049] The unit length cooling water quantity of the 1st-nth sub-sections is k1-k n times of Q respectively; wherein, k1-k n takes a value of 0.55-0.98;

[0050] The unit length cooling water quantity of the 1st-mth sub-sections is K1-K mK1~Km, wherein K1~Km are set to be equal-difference increasing. m are set to be equal-difference increasing.

[0051] Preferably, when n≥3, k1~km are set to be equal-difference increasing. n are set to be equal-difference increasing.

[0052] When m≥3, K1~Km are set to be equal-difference increasing. m are set to be equal-difference increasing.

[0053] Preferably, k1~km are set to be equal-difference increasing. n and the values of K1~Km are set to be equal-difference increasing. m respectively.

[0054] Preferably, when t is valued <10mm, k1~km are set to be equal-difference increasing. n are set to be equal-difference increasing; when 10mm≤t<15mm, k1~km are set to be equal-difference increasing. n are set to be equal-difference increasing; when 15mm≤t≤30mm, k1~km are set to be equal-difference increasing. n are set to be equal-difference increasing.

[0055] When t is valued <10mm, K1~Km are set to be equal-difference increasing. m are set to be equal-difference increasing; when 10mm≤t<15mm, K1~Km are set to be equal-difference increasing. m are set to be equal-difference increasing; when 15mm≤t≤30mm, K1~Km are set to be equal-difference increasing. m are set to be equal-difference increasing.

[0056] Preferably, when t is valued <10mm, n=m=3, k1 is valued 0.55~0.65, k2 is valued 0.65~0.75, k3 is valued 0.75~0.85, K1 is valued 0.50~0.60, K2 is valued 0.60~0.70, K3 is valued 0.70~0.80.

[0057] When 10mm≤t<15mm, n=m=3, k1 is valued 0.70~0.80, k2 is valued 0.80~0.85, k3 is valued 0.85~0.90, K1 is valued 0.65~0.75, K2 is valued 0.75~0.80, K3 is valued 0.80~0.85.

[0058] When 15mm≤t≤30mm, n=m=3, k1 is valued 0.80~0.87, k2 is valued 0.87~0.92, k3 is valued 0.92~0.98, K1 is valued 0.75~0.85, K2 is valued 0.85~0.90, K3 is valued 0.90~0.95.

[0059] Preferably, in the step "taking temperature measurements at intervals of 0.2 to 0.5 m along the longitudinal direction of the hot-rolled steel plate from beginning to end":

[0060] Temperature measurements were taken at intervals of 0.2–0.5 m along the longitudinal direction of the hot-rolled steel sheet from beginning to end.

[0061] Remove outliers.

[0062] Preferably, in the step "removing outliers":

[0063] If the temperature difference between a temperature measuring point and the temperature of an adjacent temperature measuring point reaches T... X1 The temperature difference between the above and another adjacent temperature measuring point is less than T. X2 If T is an abnormal value, then the temperature measurement point is considered an abnormal value; where T X1 Values ​​range from 60 to 80℃, T X2 The value is taken from 5 to 15℃;

[0064] Alternatively, if the temperature difference between a temperature measuring point and the temperatures of two adjacent temperature measuring points both reach T... X3 If the above values ​​are met, then the temperature measurement point is considered an abnormal value; where T... X3 The value is taken between 60 and 80℃;

[0065] Alternatively, using all temperature measurement points as the data basis, with temperature as the dependent variable and location as the independent variable, a temperature curve along the entire longitudinal length of the steel plate can be fitted. If the temperature at a temperature measurement point deviates from the temperature curve by a certain T... X4 If the above values ​​are found, the temperature measurement point is determined to be an outlier and removed; where T... X4 The value is taken between 60 and 80℃.

[0066] Preferably, the steel plate is pipeline steel, and when the steel billet is heated in the heating furnace, the temperature of the soaking zone is 1150-1220℃ and the residence time is 25-45min.

[0067] Preferably, during recrystallization rolling, the rolling temperature is 950–1050°C to obtain an intermediate billet with a thickness of 2t–6t.

[0068] Preferably, when rolling in the non-recrystallization zone, the rolling temperature is 750–850°C.

[0069] Preferably, when water cooling is performed in the ultra-fast cooling system, the final cooling temperature is 210–530°C.

[0070] Compared with the prior art, the beneficial effects of the present invention are as follows: by taking temperature measurements at points along the entire longitudinal direction of the hot-rolled steel plate, and based on the temperature measurement results and through a series of data processing schemes, the cooling temperature of the hot-rolled steel plate is controlled. Thus, on the one hand, the uniformity of the longitudinal performance of each steel plate at the head, middle and tail (i.e., the uniformity of performance within the same plate is improved) can be greatly improved. On the other hand, the performance consistency of different steel plates can be guaranteed, and the uniformity of performance of any two steel plates produced can be improved. In this way, the method can simultaneously greatly reduce the strength difference within the same plate and the strength difference between different plates, improve the performance stability of the steel plate products, and adopt a heating-rolling-cooling process without adding time-consuming or long-process processes. It also does not require high alloy content in chemical composition, resulting in high production efficiency and low production cost. Attached Figure Description

[0071] Figure 1 is a flowchart of a production method according to an embodiment of the present invention;

[0072] Figure 2 is a longitudinal top view of the steel plate in the production method of one embodiment of the present invention;

[0073] Figure 3 is a schematic diagram of the temperature curve fitted in the production method of one embodiment of the present invention. Detailed Implementation

[0074] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0075] The present invention provides a method for producing steel plates, which is particularly suitable for the production of steel plates with strict requirements on performance range and performance uniformity, such as pipeline steel.

[0076] Referring to Figure 1, the production method includes the following steps:

[0077] Steel billets with a thickness ≤320mm are heated in a heating furnace. After exiting the heating furnace, the steel billets are first rolled in the recrystallization zone and then rolled in the non-recrystallization zone to obtain hot-rolled steel plates with a longitudinal length D and a thickness t; where t is taken from 6 to 30mm.

[0078] Temperature measurements were taken at intervals of 0.2–0.5 m along the longitudinal direction of the hot-rolled steel plate from beginning to end, and the temperature measurement results were obtained.

[0079] Located vertically in D T ~(DD) W The average temperature T in the central area is calculated by measuring the temperatures at the temperature measurement points within the area. Z ;

[0080] Temperature below T Z -T T The head section of the steel plate is designated as the low-temperature head section, with a temperature lower than T.Z -T W the tail section of the steel plate as a tail low-temperature section, and the rest of the sections except the head low-temperature section and the tail low-temperature section as a middle section; wherein, T T and T W each takes any value in the range of 20-50℃;

[0081] The head low-temperature section is divided into 1st-nth sub-sections arranged in order from the head to the tail according to the measured temperature from low to high, and the tail low-temperature section is divided into 1st-mth sub-sections arranged in order from the tail to the head according to the measured temperature from low to high, n≥2, m≥2;

[0082] The hot-rolled steel plate enters the ultra-fast cooling system for water cooling; during this period, taking the unit length cooling water quantity Q of the middle section as the standard, the unit length cooling water quantity of the 1st-nth sub-sections of the head low-temperature section is controlled to increase in turn and be less than Q, and the unit length cooling water quantity of the 1st-mth sub-sections of the tail low-temperature section is controlled to increase in turn and be less than Q;

[0083] After exiting the ultra-fast cooling system, the steel plate is naturally air-cooled to room temperature on the cooling bed to obtain the steel plate product.

[0084] In this way, by taking point temperature measurement along the longitudinal direction of the hot-rolled steel plate, and based on the temperature measurement results, cooling temperature control of the hot-rolled steel plate is realized under a series of data processing schemes, and thus, on the one hand, the longitudinal performance uniformity of the head, middle and tail of each steel plate can be greatly improved (i.e., the performance uniformity of the same plate is improved), and on the other hand, the performance consistency of different steel plates can be ensured, so that the performance uniformity of any two steel plates produced is improved, and thus, the same plate strength difference and different plate strength difference are greatly reduced at the same time, the performance stability of the steel plate product is improved, and the process of heating-rolling-cooling is adopted, without the need for additional time-consuming or long-flow processes, and without the requirement of high alloy content of chemical composition, with high production efficiency and low production cost.

[0085] Specifically, by the production method, the yield strength difference of the same plate of the prepared several steel plate products is ≤40MPa, even ≤35MPa, and more even ≤30MPa; more than 80% of the several steel plate products have a different plate yield strength difference of ≤70MPa, and more than 95% have a different plate yield strength difference of ≤90MPa.

[0086] The basic inventive purpose of the present application is introduced above, and next, the specific embodiments based on the basic inventive purpose of the present application are introduced in detail.

[0087] Specifically, the production method as a whole prepares the steel plate product from the steel billet with a thickness of ≤320mm through the sequentially implemented heating, rolling and cooling processes.

[0088] In the heating and rolling process, the billet with a thickness of ≤320 mm is heated in a heating furnace, and after leaving the heating furnace, the billet is firstly subjected to recrystallization zone rolling and then non-recrystallization zone rolling to obtain a hot-rolled steel plate with a longitudinal length D and a thickness t.

[0089] The thickness t is 6-30 mm, that is, the thickness of the hot-rolled steel plate is 6-30 mm, and correspondingly, the thickness specification of the final steel plate product is 6-30 mm.

[0090] The "longitudinal direction" corresponds to the length direction of the steel plate, that is, the direction defined by the head and tail, which is parallel to the advancing direction of the steel plate on the production line.

[0091] In an embodiment, the longitudinal length D can be 12-54 m, of course, not limited thereto.

[0092] In addition, the transverse width of the hot-rolled steel plate can be 1-4.5 m, also not limited thereto.

[0093] In the present application, before the hot-rolled steel plate enters the ultrafast cooling system, it is first subjected to temperature measurement and partitioning based on the temperature measurement results to facilitate subsequent cooling in the ultrafast cooling system. For the convenience of description and understanding, the temperature measurement to partitioning stage is collectively named as the "planning process".

[0094] In the planning process:

[0095] Step S100, temperature measurement is performed on the hot-rolled steel plate along the longitudinal direction from the head to the tail at an interval of 0.2-0.5 m to obtain temperature measurement results;

[0096] Step S200, the temperature of the temperature measurement points located in the D T -(D-D W ) region in the longitudinal direction is used to calculate the central average temperature T Z ;

[0097] Step S300, the head section of the steel plate with a temperature lower than T Z -T T is taken as the head low-temperature section, the tail section of the steel plate with a temperature lower than T Z -T W is taken as the tail low-temperature section, and the remaining sections other than the head low-temperature section and the tail low-temperature section are taken as the central section; wherein T T and T W each take any value in 20-50℃;

[0098] Step S400, the head low-temperature section is divided into 1st to nth sub-sections arranged in sequence from the head according to the measured temperature from low to high, and the tail low-temperature section is divided into 1st to mth sub-sections arranged in sequence from the tail according to the measured temperature from low to high, n≥2, m≥2.

[0099] In step S100, the temperature measurement of the hot-rolled steel plate can be implemented after the hot-rolled steel plate completely leaves the hot-rolling mill, for example, a temperature measurement device is arranged at a position between the hot-rolling mill and the ultra-fast cooling system and more than D away from the hot-rolling mill to measure the temperature of the hot-rolled steel plate, and the tail of the hot-rolled steel plate has already left the hot-rolling mill when the temperature measurement is performed; or the temperature measurement of the hot-rolled steel plate can be implemented while the hot-rolled steel plate is leaving the hot-rolling mill, for example, a temperature measurement device is arranged at the outlet of the hot-rolling mill or arranged at a position between the hot-rolling mill and the ultra-fast cooling system and less than D away from the hot-rolling mill to measure the temperature of the hot-rolled steel plate, and at least when the temperature measurement of the head of the hot-rolled steel plate is performed, the tail of the hot-rolled steel plate has not left the hot-rolling mill.

[0100] In step S100, the temperature measurement is performed on points in the range of 0-D from the head to the tail in the longitudinal direction of the hot-rolled steel plate at a certain distance in the longitudinal direction, and here, on the one hand, the certain distance is 0.2-0.5 m, that is, for example, as shown in FIG. 2, the longitudinal distance D between any two adjacent temperature measurement points is 0.2-0.5 m. P On the other hand, in step S100, all the temperature measurement points are arranged in a straight line in the longitudinal direction.

[0101] Preferably, D P is 0.2 m, 0.25 m, 0.3 m, 0.35 m, 0.4 m, 0.45 m or 0.5 m.

[0102] On the other hand, in step S100, all the temperature measurement points are arranged in a straight line in the longitudinal direction.

[0103] Preferably, the width W of the hot-rolled steel plate in the transverse direction, in step S100, the temperature measurement is performed on points in the region of W / 3-2W / 3 in the middle of the transverse direction of the hot-rolled steel plate, and more preferably, the temperature measurement is performed on a point at the position of W / 2 in the middle of the transverse direction of the hot-rolled steel plate, that is, in the middle, as shown in FIG. 2.

[0104] The temperature measurement results obtained in this step S100 will serve as the data basis for the relevant processing in subsequent steps S200, S300 and S400.

[0105] In a specific embodiment, the temperatures of all the temperature measurement points obtained in step S100 can be directly used as the temperature measurement results and substituted into the corresponding data processing in subsequent steps S200, S300 and S400.

[0106] In a more preferred embodiment, the temperatures of all temperature measurement points obtained in step S100 can be first adjusted by removing outliers, and the temperatures of the remaining temperature measurement points can then be used as the measurement results and substituted into subsequent steps S200, S300, and S400 for corresponding data processing. That is, in this preferred embodiment, step S100 includes:

[0107] Sub-step S101: Take temperature measurements at points along the longitudinal direction of the hot-rolled steel plate from beginning to end at intervals of 0.2 to 0.5 m.

[0108] Sub-step S102: Remove outliers.

[0109] In this way, by removing outliers, the accuracy of subsequent steps S200, S300, and S400 can be avoided from being affected by abnormal temperature data from individual temperature measurement points.

[0110] Sub-step S102 has multiple implementations. Three different implementations are provided below, but the implementation of step S102 is not limited to these.

[0111] <First Implementation of Sub-step S102>

[0112] If the temperature T of a temperature measuring point Pb is... Pb The temperature T of an adjacent temperature measuring point Pa Pa The difference | T Pa -T Pb | Reaching T X1 The above is the temperature T of the adjacent temperature measuring point Pc. Pc The difference | T Pc -T Pb | Less than T X2 If so, then the temperature measurement point Pb is the abnormal value;

[0113] Among them, T X1 The temperature range is 60–80℃, preferably 60–70℃, and more preferably 65℃; T X2 The temperature range is 5–15℃, preferably 5–10℃, and more preferably 7℃.

[0114] Thus, according to the first implementation of sub-step S102, all temperature measurement points are checked one by one, and all abnormal values ​​are removed. The temperature of the remaining temperature measurement points is then used as the temperature measurement result of step S100 and substituted into subsequent steps S200, S300, and S400 for corresponding data processing.

[0115] <Second Implementation of Sub-step S102>

[0116] If the temperature difference between a temperature measuring point and the temperatures of two adjacent temperature measuring points both reach T... X3When the temperature T of the temperature measuring point Pb reaches T Pb When the temperature T of the temperature measuring point Pb reaches T Pa , the temperature T of the temperature measuring point Pb deviates from the temperature curve by T Pa -T Pb , and when the temperature T of the temperature measuring point Pb reaches T X3 , the temperature T of the temperature measuring point Pb deviates from the temperature curve by T Pc -T Pc , and when the temperature T of the temperature measuring point Pb reaches T Pb , the temperature T of the temperature measuring point Pb deviates from the temperature curve by T X3 , the temperature measuring point Pb is determined to be an abnormal value and removed.

[0117] T is 60-80°C, preferably 60-70°C, and more preferably 65°C. X3

[0118] In this way, according to the second implementation of the sub-step S102, all temperature measuring points are checked one by one, and all abnormal values are removed, and then the temperatures of the remaining temperature measuring points are taken as the temperature measuring results of the step S100 and are substituted into the subsequent steps S200, S300, and S400 for corresponding data processing.

[0119] <Third implementation of the sub-step S102>

[0120] A temperature curve of the full length of the steel plate in the longitudinal direction is fitted based on all temperature measuring points as data, with temperature as the dependent variable and position as the independent variable; for example, in FIG. 3, the longitudinal distance of the temperature measuring point to the head of the steel plate is the horizontal coordinate, and the temperature of the temperature measuring point is the vertical coordinate, so that the temperature curve is fitted based on the coordinates of all temperature measuring points in the coordinate system; the specific fitting method can use the conventional fitting method in mathematical science, and will not be described here.

[0121] When the temperature of a temperature measuring point deviates from the temperature curve by T X4 , the temperature measuring point is determined to be an abnormal value and removed; for example, the temperature T of a temperature measuring point Pb measured by the temperature measuring point reaches T Pb , the coordinates of the temperature measuring point in the coordinate system are (D Pb , T Pb ), and the position D Pb corresponds to the temperature T Pb ’ on the temperature curve T=f(D), so that the temperature T of the temperature measuring point Pb deviates from the temperature curve by T Pb -T Pb ’, and when the temperature T of the temperature measuring point reaches T Pb , the temperature T of the temperature measuring point Pb deviates from the temperature curve by T Pb -T Pb ’, and when the temperature T of the temperature measuring point reaches T X4 , the temperature measuring point Pb is determined to be an abnormal value and removed.

[0122] ​wherein T X4 is in the range of 60-80°C, preferably 60-70°C, more preferably 65°C.

[0123] In this way, according to the third implementation of the sub-step S102, all the temperature measurement points are checked one by one, and all the abnormal values are removed therefrom, and then the temperatures of the remaining temperature measurement points are taken as the temperature measurement results of the step S100, and are substituted into the subsequent steps S200, S300, S400 for corresponding data processing.

[0124] Next, in the step S200, the temperature of the temperature measurement point located in the region D T ~(D-D W ) in the longitudinal direction is used to calculate the middle average temperature T Z .

[0125] That is, as shown in FIG. 2, the steel plate excludes the head region 0~D T (not including the position D T ) and the tail region (D-D W )~D (not including the position D-D W ) in the longitudinal direction from the whole plate region 0~D, and uses the temperature of the temperature measurement point located in the region D T ~(D-D W ) to calculate the middle average temperature T Z .

[0126] Specifically, the temperature of the temperature measurement point located in the region D T ~(D-D W ) in the longitudinal direction can be summed and averaged to obtain the middle average temperature T Z . For example, there are h0 temperature measurement points in the region D T ~(D-D W ), and the sum of the temperatures of the h0 temperature measurement points is ∑T0, and then the middle average temperature T Z =∑T0 / h0.

[0127] wherein the values of D T and D W may be the same or different for the same steel plate; the values of D T may be the same or different, and the values of D W may be the same or different for different steel plates.

[0128] D T is in the range of 1.5-3.5m, and D W is in the range of 1.5-3.5m.

[0129] Further, D T and DW The values of t decrease step by step with the increase of t. In this way, the performance consistency of the steel plates of different thickness specifications can be further improved, that is, the stability of the steel plates of different thickness specifications is strong.

[0130] For example, when t < 10 mm, 2.75 m < D T ≤ 3.5 m, preferably D T = 3 m, 2.75 m < D W ≤ 3.5 m, preferably D W = 3 m.

[0131] When 10 mm ≤ t < 15 mm, 2.25 m < D T ≤ 2.75 m, preferably D T = 2.5 m, 2.25 m < D W ≤ 2.75 m, preferably D W = 2.5 m.

[0132] When 15 mm ≤ t ≤ 30 mm, 1.5 m < D T ≤ 2.25 m, preferably D T = 2 m, 1.5 m < D W ≤ 2.25 m, preferably D W = 2 m.

[0133] Further, in step S300, the head section of the steel plate with a temperature lower than T Z -T T is taken as the head low-temperature section, the tail section of the steel plate with a temperature lower than T Z -T W is taken as the tail low-temperature section, and the remaining section except the head low-temperature section and the tail low-temperature section is taken as the middle section.

[0134] In which, the head section of the steel plate with a temperature lower than T Z -T T is taken as the head low-temperature section, that is, the section from the head in the longitudinal direction is taken as the head low-temperature section, and the width W and the thickness t of the head low-temperature section are recorded; the tail section of the steel plate with a temperature lower than T Z -T W is taken as the tail low-temperature section, that is, the section from the tail in the longitudinal direction is taken as the tail low-temperature section, and the width W and the thickness t of the tail low-temperature section are recorded; and the remaining section of the steel plate except the head low-temperature section and the tail low-temperature section is taken as the middle section, and the width W and the thickness t of the middle section are recorded.

[0135] In this way, the head low-temperature section, the middle section, and the tail low-temperature section are arranged and connected in sequence from the head to the tail, and the sum of the longitudinal lengths of the three sections is the total length D of the hot-rolled steel plate.

[0136] In which, T TThe temperature is taken from any value between 20 and 50°C, preferably between 20 and 40°C, and more preferably 30°C.

[0137] T W The temperature is taken from any value between 20 and 50°C, preferably between 20 and 40°C, and more preferably 30°C.

[0138] T T and T W The values ​​can be the same or different.

[0139] In practice, step S300 can be implemented in various ways. Two of them are provided below. Of course, this application is not limited to these.

[0140] <First Implementation Method of Step S300>

[0141] In this embodiment, the head low-temperature section and the middle section are divided by a temperature measuring point; the tail low-temperature section and the middle section are also divided by a temperature measuring point.

[0142] As shown in Figure 2, starting from the beginning along the longitudinal direction of the steel plate, when two adjacent temperature measuring points are selected, the temperature measuring point P2 closest to the beginning of the plate... T Temperature less than T Z -T T And a temperature measuring point P1 far away from the top of the plate T The temperature reached T Z -T T In the above case, the temperature measuring point P1, which is located furthest from the plate head, is used. T To define the boundary, the head low-temperature section and the middle section are distinguished. In a variation, a temperature measuring point P2 near the head of the plate can also be used. T To define the boundary, the head low-temperature segment and the middle segment are divided.

[0143] Starting from the tail along the longitudinal direction of the steel plate, when two adjacent temperature measuring points are selected, the temperature measuring point P2 closer to the tail of the plate... W Temperature less than T Z -T W And a temperature measuring point P1 far from the tail of the plate W The temperature reached T Z -T W In the above case, the temperature measuring point P1, which is located furthest from the tail of the plate, is used. W To define the boundary, the tail section (low-temperature segment) and the middle section are distinguished. In a variation, a temperature measuring point P2 near the tail of the plate can also be used. W To define the boundary, the tail section and the middle section are divided.

[0144] In the diagram, the length of the cryogenic segment of the head is less than that of the head region 0–D. T Length (i.e., length D)T ), the length of the tail low-temperature section is less than the length of the tail region (D-D W )~D (i.e. the length D W ); and in a variable embodiment, the length of the head low-temperature section can be equal to or greater than the length of the head region 0~D T , and the length of the tail low-temperature section can be equal to or greater than the length of the tail region (D-D W )~D.

[0145] <Second embodiment of step S300>

[0146] According to the temperature measurement results, a temperature curve of the whole length of the steel plate in the longitudinal direction is fitted with temperature as the dependent variable and position as the independent variable, such as the temperature curve T=f(D) shown in Fig. 3;

[0147] The position D Z corresponding to T T -T TF on the temperature curve in the interval 0~D / 2 is confirmed, and the position D Z corresponding to T W -T WF on the temperature curve in the interval D / 2~D is confirmed;

[0148] The steel plate is divided into a head low-temperature section, a middle section and a tail low-temperature section arranged in sequence from the head to the tail in the longitudinal direction by taking the position D TF and the position D WF as the division boundary.

[0149] That is, the head low-temperature section and the middle section take the position D TF as the division boundary, and the tail low-temperature section and the middle section take the position D WF as the division boundary; the head low-temperature section occupies the section 0~D TF in the longitudinal direction of the hot-rolled steel plate, and has a transverse width W, a thickness t and a longitudinal length D TF ; the tail low-temperature section occupies the section D WF ~D in the longitudinal direction of the hot-rolled steel plate, and has a transverse width W, a thickness t and a longitudinal length D-D WF ; and the middle section occupies the section D TF ~D WF in the longitudinal direction of the hot-rolled steel plate, and has a transverse width W, a thickness t and a longitudinal length D WF -D TF .

[0150] In Fig. 3, the values of T T and T W are the same; and the present application is not limited thereto, and the values of T T and T W may also be different.

[0151] Next, in step S400, the head low-temperature section is divided into first to nth sub-sections arranged in order from the head according to the measured temperatures from low to high, and the tail low-temperature section is divided into first to mth sub-sections arranged in order from the tail according to the measured temperatures from low to high.

[0152] Wherein, n≥2, m≥2.

[0153] Preferably, n≥3, m≥3.

[0154] On the same steel plate, n and m can be the same or different.

[0155] That is, the head low-temperature section is divided into first to nth sub-sections arranged in order from the head to the middle section along the longitudinal direction, the nth sub-section is connected with the middle section, and the temperatures of the first to nth sub-sections are from low to high.

[0156] Similarly, the tail low-temperature section is divided into first to mth sub-sections arranged in order from the tail to the middle section along the longitudinal direction, the mth sub-section is connected with the middle section, and the temperatures of the first to mth sub-sections are from low to high.

[0157] Further, in step S400:

[0158] According to the temperature span of each sub-section, the temperature span of each sub-section does not exceed T Tk , the head low-temperature section is divided into n sub-sections;

[0159] According to the temperature span of each sub-section, the temperature span of each sub-section does not exceed T Wk , the tail low-temperature section is divided into m sub-sections.

[0160] In this application, the temperature span refers to the difference between the highest temperature and the lowest temperature.

[0161] That is, for each of the first to nth sub-sections, the highest temperature and the lowest temperature do not exceed T Tk ; for each of the first to mth sub-sections, the highest temperature and the lowest temperature do not exceed T Wk .

[0162] As for the specific values of T Tk , T Wk , the application has various embodiments, and several preferred embodiments are provided below.

[0163] The first embodiment of the values of T Tk , T Wk

[0164] In this embodiment, referring to FIG. 2, among all the temperature measuring points in the head low-temperature section, the temperature measuring point P5 T ​The temperature is lowest at this temperature measurement point P5. T The temperature constitutes the lowest temperature range T among all temperature measurement points in the low-temperature segment of the entire head. T0 .

[0165] Furthermore, among all the temperature measurement points in the low-temperature segment of the head, temperature measurement point P1 T The temperature is highest at this temperature measurement point P1. T The temperature constitutes the highest temperature T among all the temperature measurement points in the low-temperature section of the entire head. T1 .

[0166] T Tk The highest temperature T among all temperature measurement points in the low-temperature section of the head. T1 and the lowest temperature range T T0 The difference T T1 -T T0 1 / n.

[0167] Thus, the temperature span of each of the first to nth sub-segments of the low-temperature segment in the head does not exceed (T). T1 -T T0 ) / n.

[0168] For example, in Figure 2, n=3, meaning the head low-temperature segment is divided into 3 sub-segments, namely the first sub-segment Z1. T , second sub-segment Z2 T , third sub-segment Z3 T ; Sub-segment Z1 T The temperature range does not exceed (T) T1 -T T0 ) / 3, the second sub-segment Z2 T The temperature range does not exceed (T) T1 -T T0 ) / 3, the third sub-segment Z3 T The temperature range does not exceed (T) T1 -T T0 ) / 3.

[0169] With the third sub-segment Z3 T For a more detailed example, temperature measurement point P1 T The temperature defines the third sub-segment Z3 T The highest temperature, temperature measurement point P3 T The temperature defines the third sub-segment Z3 T The lowest temperature range, temperature measurement point P1 T and temperature measurement point P3 T The temperature difference defines the third sub-segment Z3 T The temperature range does not exceed (T T1 -T T0 ) / 3.

[0170] Similarly, among all the temperature measuring points in the tail low-temperature section, the temperature measuring point P5 W has the lowest temperature, and the temperature of the temperature measuring point P5 W constitutes the lowest temperature section T W0 among all the temperature measuring points in the tail low-temperature section.

[0171] Moreover, among all the temperature measuring points in the tail low-temperature section, the temperature measuring point P1 W has the highest temperature, and the temperature of the temperature measuring point P1 W constitutes the highest temperature T W1 among all the temperature measuring points in the tail low-temperature section.

[0172] T Wk is the difference between the highest temperature T W1 and the lowest temperature section T W0 of each temperature measuring point in the tail low-temperature section, and T W1 -T W0 is 1 / m.

[0173] Therefore, in each of the first to mth sub-sections of the tail low-temperature section, the temperature span does not exceed (T W1 -T W0 ) / m.

[0174] For example, in FIG. 2, m=3, i.e., the tail low-temperature section is divided into three sub-sections, namely, the first sub-section Z1 W , the second sub-section Z2 W , and the third sub-section Z3 W ; the temperature span of the first sub-section Z1 W does not exceed (T W1 -T W0 ) / 3, the temperature span of the second sub-section Z2 W does not exceed (T W1 -T W0 ) / 3, and the temperature span of the third sub-section Z3 W does not exceed (T W1 -T W0 ) / 3.

[0175] Taking the third sub-section Z3 W as an example in more detail, the temperature of the temperature measuring point P1 W defines the highest temperature of the third sub-section Z3 W , the temperature of the temperature measuring point P3 W defines the lowest temperature section of the third sub-section Z3 W , and the difference between the temperature of the temperature measuring point P1 W and the temperature of the temperature measuring point P3 W defines the temperature span of the third sub-section Z3 W , which does not exceed (TW1 -T W0 ) / 3.

[0176] <T Tk T Wk The second implementation method for obtaining values>

[0177] In this embodiment, referring to Figure 3, the highest temperature of the temperature curve T = f(D) in the low-temperature segment of the head is T. Z -T T The corresponding longitudinal position of the steel plate is position D. TF .

[0178] Furthermore, the lowest temperature segment T in the low-temperature segment of the temperature curve T = f(D) in the head is... T0 The corresponding longitudinal position of the steel plate is position 0 (that is, the ordinate value when the abscissa in the coordinate system is 0 is the lowest temperature range T). T0 Of course, in implementing the changes, the temperature value at position 0 may not be taken as the lowest temperature range T. T0 Instead of ', we take the temperature value at a position slightly greater than 0 as the lowest temperature range T'. T0 '.

[0179] T Tk The highest temperature T in the low-temperature segment of the head is represented by the temperature curve T = f(D). Z -T T and the lowest temperature range T T0 'difference T' Z -T T -T T0 'of 1 / n.

[0180] Thus, the temperature span of each of the first to nth sub-segments of the low-temperature segment in the head does not exceed (T). Z -T T -T T0 ') / n.

[0181] For example, in Figure 3, n=2, meaning the low-temperature segment of the head is divided into two sub-segments, namely the first sub-segment Z1. T , second sub-segment Z2 T ; Sub-segment Z1 T The temperature range does not exceed (T) Z -T T -T T0 ') / 2, the second sub-segment Z2 T The temperature range does not exceed (T) Z -T T -T T0 ') / 2.

[0182] With the second sub-segment Z2T For a more detailed example, the coordinates of the temperature measurement curve (D) TF ,T Z -T T The second sub-segment Z2 is defined. T The highest temperature T Z -T T Coordinates of point (D) TF1 ,T TF1 The second sub-segment Z2 is defined. T The lowest temperature range T TF1 Therefore, the second sub-segment Z2 T Temperature span T Z -T T -T TF1 ≤(T Z -T T -T T0 ') / 2.

[0183] Similarly, the first sub-segment Z1 T Temperature span T TF1 -T T0 '≤(T Z -T T -T T0 ') / 2.

[0184] Furthermore, in one embodiment, the temperature span of at least the first to (n-1)th sub-segments of the low-temperature section of the head can be (T... Z -T T -T T0 ') / n, the temperature span of the nth sub-segment is ≤ (T) Z -T T -T T0 ') / n; or, it can be that the temperature span of at least the 2nd to nth sub-segments is (T) / n. Z -T T -T T0 ') / n, the temperature span of the first sub-segment ≤ (T) Z -T T -T T0 ') / n;

[0185] Similarly, referring to Figure 3, the highest temperature of the temperature curve T = f(D) in the low-temperature section at the tail is T. Z -T W The corresponding longitudinal position of the steel plate is position D. WF .

[0186] Furthermore, the lowest temperature segment T in the low-temperature section of the temperature curve T = f(D) at the tail end... W0The corresponding longitudinal position of the steel plate is position D (that is, when the horizontal coordinate of the coordinate system is D, the vertical coordinate value is the lowest temperature range T). W0 Of course, in implementing the changes, the temperature value at location D may not be taken as the lowest temperature range T. W0 Instead, it is replaced by taking the temperature value at a location slightly smaller than D as the lowest temperature range T. W0 '.

[0187] T Wk The highest temperature T in the low-temperature section of the tail end of the temperature curve T = f(D) is... Z -T W and the lowest temperature range T W0 'difference T' Z -T W -T W0 'of 1 / m.

[0188] Thus, the temperature span of each of the first to m sub-segments of the low-temperature tail section does not exceed (T). Z -T W -T W0 ') / m.

[0189] For example, in Figure 3, m=2, meaning the low-temperature tail section is divided into two sub-segments, namely the first sub-segment Z1. W , second sub-segment Z2 W ; Sub-segment Z1 W The temperature range does not exceed (T) Z -T W -T W0 ') / 2, the second sub-segment Z2 W The temperature range does not exceed (T) Z -T W -T W0 ') / 2.

[0190] With the second sub-segment Z2 W For a more detailed example, the coordinates of the temperature measurement curve (D) WF ,T Z -T W The second sub-segment Z2 is defined. W The highest temperature T Z -T W Coordinates of point (D) WF1 ,T WF1 The second sub-segment Z2 is defined. W The lowest temperature range T WF1 Therefore, the second sub-segment Z2 W Temperature span T Z -T W -T WF1 ≤(TZ -T W -T W0 ’) / 2.

[0191] Similarly, the temperature span T W of the first sub-zone Z1 WF1 -T W0 ’≤(T Z -T W -T W0 ’) / 2.

[0192] Further, in an embodiment, in the first to mth sub-zones of the tail low-temperature section, the temperature span of at least the first to (m-1)th sub-zones can be (T Z -T W -T W0 ’) / m, and the temperature span of the mth sub-zone can be ≤(T Z -T W -T W0 ’) / m; or, the temperature span of at least the second to mth sub-zones can be (T Z -T W -T W0 ’) / m, and the temperature span of the first sub-zone can be ≤(T Z -T W -T W0 ’) / m.

[0193] <T Tk , T Wk of the third embodiment

[0194] In this embodiment, T Tk is a temperature span predetermined value T n , which is preferably any value in the range of 5-20℃, for example 10℃; and T Wk is a temperature span predetermined value T m , which is preferably any value in the range of 5-20℃, for example 10℃.

[0195] That is, the temperature span of each of the first to nth sub-zones of the head low-temperature section does not exceed T n ; and the temperature span of each of the first to mth sub-zones of the tail low-temperature section does not exceed T m .

[0196] Thus, in an embodiment, when the sub-zones are divided by the temperature measurement points, taking FIG. 2 as an example:

[0197] In the head low-temperature section, the temperature difference between any two temperature measurement points of the first sub-zone Z1 T does not exceed T nThe second sub-segment Z2 T The temperature difference between any two temperature measuring points does not exceed T. n , third sub-segment Z3 T The temperature difference between any two temperature measuring points does not exceed T. n For example, temperature measurement point P1 T and temperature measurement point P3 T The temperature difference defines the third sub-segment Z3 T The temperature span, which does not exceed T n ;

[0198] Similarly, in the low-temperature tail section, the first sub-segment Z1 W The temperature difference between any two temperature measuring points does not exceed T. m The second sub-segment Z2 W The temperature difference between any two temperature measuring points does not exceed T. m The third sub-segment Z3 W The temperature difference between any two temperature measuring points does not exceed T. m For example, temperature measurement point P1 W and temperature measurement point P3 W The temperature difference defines the third sub-segment Z3 W The temperature span does not exceed T. m .

[0199] In a variation of the implementation, where the temperature curve is fitted using the temperature measurement results, as shown in Figure 3:

[0200] In the low-temperature segment of the head, the first sub-segment Z1 T Temperature span T TF1 -T T0 '≤T n The second sub-segment Z2 T Temperature span T Z -T T -T TF1 ≤T n ;

[0201] Similarly, in the low-temperature tail section, the first sub-segment Z1 W Temperature span T WF1 -T W0 '≤T m The second sub-segment Z2 W Temperature span T Z -T W -T WF1 ≤T m ;

[0202] Furthermore, in this variant embodiment, the temperature span of at least the first to (n-1)th sub-segments of the low-temperature section of the head can be T. n The temperature span of the nth sub-segment is ≤ T n Alternatively, the temperature span of at least the 2nd to nth sub-segments can be T. n The temperature span of the first sub-segment is ≤ T n ;

[0203] Similarly, in the first to m sub-segments of the low-temperature tail section, the temperature span of at least the first to (m-1) sub-segments can be T. m The temperature span of the m-th sub-segment is ≤ T m Alternatively, the temperature span of at least the 2nd to mth sub-segments could be T. m The temperature span of the first sub-segment is ≤ T m .

[0204] Next, in step S400, as before... <T Tk T Wk The first method of obtaining the value> <T Tk T Wk The third implementation method of the value is adapted to the following: In the first to nth sub-segments, two adjacent sub-segments can be divided by a temperature measurement point; In the first to m sub-segments, two adjacent sub-segments can be divided by a temperature measurement point.

[0205] Specifically, for example, in one embodiment, starting from the first temperature measuring point near the head of the low-temperature segment, when the temperature of one of two adjacent temperature measuring points near the head of the plate differs from the lowest temperature segment of that sub-section by no more than T... Tk The temperature difference between a temperature measuring point far from the plate head and the lowest temperature range of that sub-section exceeds T. Tk When the temperature measurement point near the plate head is used as the dividing line, the sub-segment and the next sub-segment are divided.

[0206] For example, referring to Figure 2, two adjacent temperature measurement points P6 T P4 T In the middle, if the temperature measuring point P6 is close to the top of the plate... T Temperature and sub-segment Z1 T The lowest temperature range (i.e., temperature measurement point P5) T The temperature difference does not exceed T Tk The temperature measuring point P4, which is far from the top of the plate, T Temperature and sub-segment Z1 T The lowest temperature range (i.e., temperature measurement point P5) T The temperature difference exceeds T Tk At that time, the temperature measurement point P6 is used.T To divide the sub-zone Z1 T and the next sub-zone Z2 T ; and so on until the last temperature point P1 T farthest from the head of the head low-temperature section, the division of the first-nth sub-zone is completed.

[0207] Similarly, starting from the first temperature point near the tail of the tail low-temperature section, when the temperature of the temperature point near the tail of the two adjacent temperature points exceeds the temperature of the lowest temperature section of the sub-zone by more than T Wk , and the temperature of the temperature point farthest from the tail exceeds the temperature of the lowest temperature section of the sub-zone by more than T Wk , the temperature point near the tail is taken as the division boundary to divide the sub-zone and the next sub-zone.

[0208] For example, referring to FIG. 2, among the two adjacent temperature points P6 W , P4 W , if the temperature of the temperature point P6 W near the tail exceeds the temperature of the lowest temperature section of the sub-zone Z1 W (i.e. the temperature of the temperature point P5 W ) by more than T Wk , and the temperature of the temperature point P4 W farthest from the tail exceeds the temperature of the lowest temperature section of the sub-zone Z1 W (i.e. the temperature of the temperature point P5 W ) by more than T Wk , the temperature point P6 W is taken as the division boundary to divide the sub-zone Z1 W and the next sub-zone Z2 W ; and so on until the last temperature point P1 W farthest from the tail of the tail low-temperature section, the division of the first-mth sub-zone is completed.

[0209] Of course, in a simple variation embodiment, starting from the first temperature point nearest to the center of the head low-temperature section (e.g. the temperature point P1 T in FIG. 2), when among the two adjacent temperature points (e.g. the temperature points P3 T , P4 T in FIG. 2), the temperature of the temperature point (e.g. the temperature point P3 T in FIG. 2) near the center exceeds the temperature of the lowest temperature section of the sub-zone by more than T Tk , and the temperature of the temperature point (e.g. the temperature point P4 T in FIG. 2) farthest from the center exceeds the temperature of the lowest temperature section of the sub-zone by more than T TkThen, a temperature measuring point near the center of the plate (e.g., temperature measuring point P3 in Figure 2) is used. T To define the boundaries, the sub-segment is divided (e.g., sub-segment Z3 in Figure 2). T ) and the next sub-segment (e.g., sub-segment Z2 in Figure 2) T ); and so on, until reaching the temperature measuring point P5 furthest from the center of the plate in the low-temperature section at the head. T Complete the division of the first to nth sub-segments;

[0210] Alternatively, the temperature can be measured from the first temperature measuring point closest to the center of the plate in the low-temperature section at the tail (e.g., temperature measuring point P1 in Figure 2). W (Starting from point P3 in Figure 2) when two adjacent temperature measuring points (e.g., temperature measuring point P3 in Figure 2) are... W P4 W In the figure, a temperature measuring point near the center of the plate (e.g., temperature measuring point P3 in Figure 2) W The temperature difference between the lowest temperature range of this sub-section and the lowest temperature range of this sub-section shall not exceed T. Wk A temperature measuring point far from the center of the plate (e.g., temperature measuring point P4 in Figure 2) W The temperature difference between the lowest temperature range of this sub-section and the lowest temperature range exceeds T. Wk Then, a temperature measuring point near the center of the plate (e.g., temperature measuring point P3 in Figure 2) is used. W To define the boundaries, the sub-segment is divided (e.g., sub-segment Z3 in Figure 2). W ) and the next sub-segment (e.g., sub-segment Z2 in Figure 2) W ); and so on, until reaching the temperature measuring point P5 furthest from the center of the plate in the low-temperature section at the tail end. W Complete the division of sub-segments from 1 to m.

[0211] Thus far, the planning process and its specific implementation methods described in this invention have been described in detail. Of course, under the technical spirit of this invention, other alternative methods with simple changes based on the embodiments described in this application do not depart from the technical spirit of this application.

[0212] Next, in the cooling process, the hot-rolled steel plate first enters the ultra-fast cooling system for water cooling, and then exits the ultra-fast cooling system. After that, the steel plate is naturally air-cooled to room temperature on the cooling bed to obtain the finished steel plate.

[0213] During water cooling in the ultra-fast cooling system, the final cooling temperature is 210–530℃. That is, the overall temperature of the steel plate when exiting the ultra-fast cooling system is within the range of 210–530℃.

[0214] In practice, the value of Q can be set according to various parameters such as the final cooling temperature, the length of the ultra-rapid cooling system, and the roller speed (i.e., the forward speed of the steel plate on the ultra-rapid cooling system) to ensure that the overall temperature of the steel plate when it exits the ultra-rapid cooling system is within the final cooling temperature range. The method of setting Q according to various parameters is a conventional approach in this field and will not be elaborated upon.

[0215] For pipeline steel, the preferred final cooling temperature is 260–420℃.

[0216] Furthermore, the final cooling temperature can preferably be 360–420℃, which has an excellent promoting effect on the microstructure and properties of X60 grade pipeline steel; the final cooling temperature can also preferably be 265–345℃, which has an excellent promoting effect on the microstructure and properties of X70 grade pipeline steel; the final cooling temperature can also preferably be 270–370℃, which has an excellent promoting effect on the microstructure and properties of X80 grade pipeline steel.

[0217] In the ultra-fast cooling system, when water cooling is performed, the cooling water volume per unit length Q of the middle section is used as the standard. The cooling water volume per unit length of the first to nth sub-sections of the low-temperature section at the head is controlled to increase sequentially and be less than Q. The cooling water volume per unit length of the first to mth sub-sections of the low-temperature section at the tail is controlled to increase sequentially and be less than Q.

[0218] In other words, the cooling water volume per unit length of the first to nth sub-segments and the first to mth sub-segments is all less than the cooling water volume per unit length Q of the middle section. Furthermore, the cooling water volume per unit length of the head low-temperature section increases in a stepwise manner from the head of the plate to the middle of the plate, and the cooling water volume per unit length of the tail low-temperature section increases in a stepwise manner from the tail of the plate to the middle of the plate.

[0219] Here, the cooling water volume per unit length refers to the cooling water volume per unit length along the longitudinal direction of the steel plate, and its unit of measurement is, for example, L / m.

[0220] Furthermore, the cooling water volume per unit length of the 1st to nth sub-segments are respectively k1 to kn of Q. n times.

[0221] That is, in the low-temperature section at the head, the cooling water volume per unit length of the first sub-section is k1 times Q; the cooling water volume per unit length of the second sub-section is k2 times Q; ...; the cooling water volume per unit length of the nth sub-section is k times Q. n times.

[0222] Among them, k1~k n The value ranges from 0.55 to 0.98.

[0223] Preferably, when n≥3, k1~k n Set it to an arithmetic progression.

[0224] Similarly, the cooling water volume per unit length of the first to m sub-sections are respectively K1 to K of Q. m times.

[0225] That is, in the low-temperature tail section, the cooling water volume per unit length of the first sub-section is K1 times Q; the cooling water volume per unit length of the second sub-section is K2 times Q; ...; the cooling water volume per unit length of the m-th sub-section is K1 times Q. n times.

[0226] Among them, K1~K m The value ranges from 0.50 to 0.95.

[0227] Preferably, when m≥3, K1~K m Set it to an arithmetic progression.

[0228] In one embodiment, k1~k n The values ​​of ... m The values ​​of increase with increasing t. Thus, for two steel plates with different thicknesses t, corresponding values ​​of k1 to k2 can be used. n K1~K m Cooling regulation is implemented to improve the performance uniformity of different steel plates.

[0229] In one embodiment, when t is less than 10 mm, k1 to k n Values ​​range from 0.55 to 0.85, K1 to K m The value ranges from 0.50 to 0.80; when 10mm ≤ t < 15mm, k1 ~ k n Values ​​range from 0.70 to 0.90, K1 to K m The value ranges from 0.65 to 0.85; when 15mm ≤ t ≤ 30mm, k1 ~ k n Values ​​range from 0.80 to 0.98, K1 to K m The value ranges from 0.75 to 0.95.

[0230] For example, taking n = m = 3 as an example, when t is less than 10 mm:

[0231] k1 takes a value of 0.55 to 0.65, which means that the cooling water volume per unit length of the first sub-section of the low-temperature section at the head is (0.55 to 0.65)Q.

[0232] k2 takes a value of 0.65 to 0.75, which means that the cooling water volume per unit length of the second sub-section of the low-temperature section at the head is (0.65 to 0.75)Q;

[0233] k3 is 0.75-0.85, i.e. the unit length cooling water amount of the third sub-section of the head low temperature section is (0.75-0.85)Q;

[0234] K1 is 0.50-0.60, i.e. the unit length cooling water amount of the first sub-section of the tail low temperature section is (0.50-0.60)Q;

[0235] K2 is 0.60-0.70, i.e. the unit length cooling water amount of the second sub-section of the tail low temperature section is (0.60-0.70)Q;

[0236] K3 is 0.70-0.80, i.e. the unit length cooling water amount of the third sub-section of the tail low temperature section is (0.70-0.80)Q.

[0237] Taking n=m=3 as an example, when 10mm≤t<15mm:

[0238] k1 is 0.70-0.80, i.e. the unit length cooling water amount of the first sub-section of the head low temperature section is (0.70-0.80)Q;

[0239] k2 is 0.80-0.85, i.e. the unit length cooling water amount of the second sub-section of the head low temperature section is (0.80-0.85)Q;

[0240] k3 is 0.85-0.90, i.e. the unit length cooling water amount of the third sub-section of the head low temperature section is (0.85-0.90)Q;

[0241] K1 is 0.65-0.75, i.e. the unit length cooling water amount of the first sub-section of the tail low temperature section is (0.65-0.75)Q;

[0242] K2 is 0.75-0.80, i.e. the unit length cooling water amount of the second sub-section of the tail low temperature section is (0.75-0.80)Q;

[0243] K3 is 0.80-0.85, i.e. the unit length cooling water amount of the third sub-section of the tail low temperature section is (0.80-0.85)Q.

[0244] Taking n=m=3 as an example, when 15mm≤t≤30mm:

[0245] k1 is 0.80-0.87, i.e. the unit length cooling water amount of the first sub-section of the head low temperature section is (0.80-0.87)Q;

[0246] k2 is 0.87-0.92, i.e. the unit length cooling water amount of the second sub-section of the head low temperature section is (0.87-0.92)Q;

[0247] k3 is 0.92-0.98, i.e. the unit length cooling water amount of the third sub-section of the head low-temperature section is (0.92-0.98)Q;

[0248] K1 is 0.75-0.85, i.e. the unit length cooling water amount of the first sub-section of the tail low-temperature section is (0.75-0.85)Q;

[0249] K2 is 0.85-0.90, i.e. the unit length cooling water amount of the second sub-section of the tail low-temperature section is (0.85-0.90)Q;

[0250] K3 is 0.90-0.95, i.e. the unit length cooling water amount of the third sub-section of the tail low-temperature section is (0.90-0.95)Q.

[0251] Further, the ultrafast cooling system usually includes 24 groups of headers, each of which can spray water on the steel plate to cool the steel plate, and the longitudinal length covered by each group of headers is about 1 m, and in actual implementation, the water spraying amount of each group of headers can be regulated or shielded to adjust the unit length cooling water amount of each section of the steel plate.

[0252] Further, in an embodiment of the present application, the steel plate is a pipeline steel, i.e. the chemical composition thereof meets the basic requirements of the chemical composition of the pipeline steel.

[0253] In a preferred embodiment, the chemical composition of the steel plate includes, in mass percentage: C 0.030-0.080%, Si 0.11-0.24%, Mn 1.51-1.69%, Cr 0.01-0.18%, Ni 0.01-0.16%, Cu 0.01-0.08%, Mo≤0.13%, Nb 0.024-0.065%, Ti 0.011-0.019%, Al 0.021-0.049%, P≤0.020%, S≤0.0050%, N≤0.0051%, and the rest is iron and inevitable impurities.

[0254] The effects and mechanisms of each element in the above chemical composition are described below.

[0255] C: the most economical strengthening element in steel, which has solid solution strengthening effect and can form carbides with Nb, Ti, Cr, Mo, etc. to have precipitation strengthening effect. The increase of carbon content can improve the strength and hardness of the pipeline steel, but too high carbon will lead to poor low-temperature toughness and welding performance, therefore, the carbon content is selected to be 0.030-0.080%.

[0256] Si: It has solid solution strengthening effect in steel, too much silicon is easy to produce Fe2SiO4 on the surface of slab, which is not conducive to the control of the surface quality of steel plate, therefore, it is selected as 0.11-0.24%.

[0257] Mn: It has solid solution strengthening effect in steel, improves strength and hardness, reasonable manganese content can ensure the strength of pipeline steel at low cost, but too much manganese will lead to center segregation of casting blank, which has great harm to toughness, therefore, it is selected as 1.51-1.69%.

[0258] Cr: It has solid solution strengthening effect in steel, at the same time, as ferrite forming element, more acicular ferrite structure can be obtained in high niobium steel, but too high, it will increase the microhardness of pipeline steel and reduce the low temperature toughness. Therefore, it is selected as 0.01-0.18%.

[0259] Ni: It has solid solution strengthening effect in steel, improves the strength of steel and does not significantly increase the hardness of steel, and is beneficial to low temperature toughness, but too high, the alloy cost increases. Therefore, it is selected as 0.01-0.16%.

[0260] Cu: It can promote the precipitation of niobium and make up for the strength loss caused by the decrease of carbon content, adding a certain amount of nickel while adding copper can effectively inhibit the surface crack of continuous casting blank. But when the content is higher, it is not conducive to the welding performance. Therefore, it is selected as 0.01-0.08%.

[0261] Mo: It can significantly improve the hardenability of steel, delay ferrite transformation and obtain acicular ferrite structure, which is beneficial to improve the strength and toughness of pipeline steel, but molybdenum leads to the increase of the number of MA components, which is not conducive to toughness, and the content is too high, the alloy cost increases significantly. Therefore, it is selected as ≤0.13%.

[0262] Nb: It is an important grain refining element in steel, in the process of hot rolling, niobium strongly inhibits austenite recrystallization and its precipitation in austenite, pins austenite grain boundary and refines recrystallized grain. In the cooling process, it can continue to precipitate in the form of niobium carbonitride, which can significantly refine the structure and further improve the strength and toughness. Adding too much niobium will first increase the alloy cost, second, niobium cannot be completely solidified in normal heating process, third, the precipitation strengthening of niobium is not conducive to the yield ratio. Therefore, it is selected as 0.024-0.065%.

[0263] Ti: It is a solid nitrogen element in steel, which can form dispersed titanium nitride particles, inhibit austenite grain coarsening during billet heating and rolling, and when the addition amount is too high, it is easy to form coarse carbon / nitride precipitates in the center of casting blank, which affects the low temperature toughness. Therefore, it is selected as 0.011-0.019%.

[0264] Al: a deoxidizing element in the steel, excessive aluminum is easy to increase Al2O3 inclusions in the steel, affecting the low temperature toughness, on the basis of ensuring the deoxidizing effect, the aluminum content should be reduced as much as possible. Therefore, the selection is 0.021-0.049%.

[0265] P: an impurity element in the steel, excessive phosphorus is easy to produce segregation, which makes the plastic toughness decrease obviously, but too low phosphorus will greatly increase the steelmaking cost, therefore, the selection is ≤0.020%. More preferably, between 0.009-0.020%.

[0266] S: an impurity element in the steel, not only increases the hot brittleness of the steel plate, is easy to form MnS inclusions with manganese, reduces the low temperature toughness of the steel, but too low sulfur will increase the steelmaking cost, therefore, the selection is ≤0.0050%. More preferably, between 0.001-0.005%.

[0267] N: an impurity element in the steel, reduces the plastic toughness of the steel plate, too low nitrogen will increase the steelmaking cost, therefore, the selection is ≤0.0051%. More preferably, between 0.0021-0.0051%.

[0268] As described before, when the production method of the application is used for preparing pipeline steel, not only the performance uniformity can be improved, the same plate strength difference and different plate strength difference of the steel plate can be reduced, but also the chemical composition of high alloy content and the low efficiency process of stacking in the prior art are avoided, which has the advantages of low cost and high efficiency, can solve the difficulties in the field of pipeline steel plate production, and greatly promotes the development of pipeline industry.

[0269] Further, in the heating process of the production method, the temperature of the soaking section is controlled to be 1150-1220℃, and the residence time is 25-45min.

[0270] The temperature difference between the head and tail of the billet after discharging is ≤15℃, and the temperature difference between the upper and lower surfaces is ≤15℃.

[0271] Furthermore, in the rolling process, the rolling temperature during the recrystallization zone rolling is 950-1050℃, and the intermediate billet with a thickness of 2t-6t is obtained.

[0272] The temperature difference between the head and tail of the intermediate billet is ≤20℃, and the temperature difference between the upper and lower surfaces is ≤20℃.

[0273] The rolling temperature during the non-recrystallization zone rolling is 750-850℃.

[0274] Further preferably, in the rolling process, between the recrystallization zone rolling and the non-recrystallization zone rolling, the intermediate billet can be cooled by temperature control in the way of air cooling, water cooling, or air cooling combined with water cooling.

[0275] The temperature difference between the head and the tail of the intermediate blank is less than or equal to 25 DEG C after temperature control cooling and before non-recrystallization zone rolling.

[0276] Furthermore, in an embodiment of the present application, the billet in the production method can be prepared by means of steelmaking and continuous casting, and the specific steelmaking and continuous casting technology can adopt the conventional disclosed technology in the field.

[0277] Further, in an embodiment of the present application, the chemical composition of the obtained steel plate includes, in terms of mass percentage: C 0.050-0.080%, Si 0.11-0.18%, Mn 1.51-1.59%, Cr 0.01-0.08%, Ni 0.01-0.08%, Cu 0.01-0.08%, Nb 0.024-0.036%, Ti 0.011-0.019%, Al 0.021-0.049%, P 0.0090-0.0190%, S 0.0010-0.0048%, N 0.0021-0.0051%, and the rest is iron and inevitable impurities.

[0278] The steel plate with the chemical composition is suitable for the preparation of pipeline steel of X60 strength grade.

[0279] The metallographic structure of the obtained steel plate is a complex phase structure of quasi-polygonal ferrite + acicular ferrite + tempered bainite, the area ratio of quasi-polygonal ferrite and acicular ferrite is greater than or equal to 85%, and the area ratio of tempered bainite is less than or equal to 15%.

[0280] Here, the metallographic structure of the steel plate can be obtained by adopting the standard GB / T 15125-2009 "Metallic Materials Specimen and Test Method for Metallographic Examination".

[0281] Furthermore, the average grain size of the ferrite of the obtained steel plate is 5-10 μm.

[0282] In terms of mechanical strength, the yield strength R t0.5 of the obtained steel plate is greater than or equal to 440 MPa, the tensile strength R m is greater than or equal to 550 MPa, the elongation A 50 is greater than or equal to 30%, and the yield strength ratio is less than or equal to 0.80; the yield strength difference of the same plate is less than or equal to 30 MPa; and among 1000 steel plate products, more than 90% of the number of steel plates have a yield strength difference of different plates less than or equal to 55 MPa, and more than 98% of the number of steel plates have a yield strength difference of different plates less than or equal to 75 MPa.

[0283] Here, the mechanical property detection can be carried out according to GB / T 228.1-2021 "Metallic Materials Tensile Test Part 1: Room Temperature Test Method".

[0284] In terms of low-temperature toughness, the obtained steel plate has a -20℃ impact energy KV2≥350J, a -40℃ impact energy KV2≥300J, and a -60℃ impact energy KV2≥250J.

[0285] Here, the low-temperature toughness can be detected according to GB / T 229-2007 "Metallic Materials Charpy Pendulum Impact Test Method".

[0286] In addition, the hardness of the obtained steel plate is ≤200HV10.

[0287] The -10℃ DWTT drop hammer shear area percentage is 100%, the -20℃ DWTT drop hammer shear area percentage is ≥98%, and the DWTT brittle transition temperature is lower than -20℃.

[0288] In a variant, the chemical composition of the obtained steel plate includes, in mass percentage: C 0.040-0.070%, Si 0.16-0.24%, Mn 1.61-1.69%, Cr 0.14-0.18%, Ni 0.11-0.16%, Cu 0.01-0.08%, Mo 0.05-0.11%, Nb 0.041-0.055%, Ti 0.011-0.019%, Al 0.021-0.049%, P 0.0090-0.0140%, S 0.0010-0.0038%, N 0.0021-0.0051%, and the rest is iron and inevitable impurities.

[0289] The steel plate with the chemical composition is suitable for the preparation of X70 strength grade pipeline steel.

[0290] The obtained steel plate has a microstructure of quasi-polygonal ferrite + acicular ferrite + bainite + tempered bainite, the area percentage of quasi-polygonal ferrite and acicular ferrite is 40-70%, and the area percentage of bainite + tempered bainite is 30-60%; and the MA proportion in bainite is ≤20%, and the MA self-tempering decomposition proportion is ≥30%.

[0291] Here, the microstructure of the steel plate can be obtained by microstructure detection according to GB / T 15125-2009 "Metallic Materials Microstructure Test Sample and Test Method".

[0292] Furthermore, the average grain size of the ferrite of the obtained steel plate is 4-7μm.

[0293] In terms of mechanical strength, the obtained steel plate has a yield strength R t0.5 ≥500MPa, a tensile strength R m ≥620MPa, and an elongation A 50≥30%, yield ratio ≤0.80; the same plate yield strength difference ≤35 MPa; and in 1000 steel plate products, more than 90% of the number of steel plates, the yield strength difference of different plates ≤60 MPa, more than 98% of the number of steel plates, the yield strength difference of different plates ≤80 MPa.

[0294] Here, the mechanical property detection can be carried out according to GB / T 228.1-2021 "Metallic Materials Tensile Testing Part 1: Room Temperature Test Method".

[0295] In terms of low temperature toughness, the obtained steel plate has an impact energy KV2 of-20℃ of ≥380J, an impact energy KV2 of-40℃ of ≥300J, and an impact energy KV2 of-60℃ of ≥270J.

[0296] Here, the low temperature toughness detection can be carried out according to GB / T 229-2007 "Metallic Materials Charpy Pendulum Impact Test Method".

[0297] In addition, the hardness of the obtained steel plate is ≤208HV10.

[0298] The DWTT drop hammer shear area percentage of-10℃ is 100%, the DWTT drop hammer shear area percentage of-20℃ is ≥90%, and the DWTT ductile-brittle transition temperature is lower than-20℃.

[0299] In yet another variant embodiment, the chemical composition of the obtained steel plate includes, in mass percentage: C 0.030-0.060%, Si 0.16-0.24%, Mn 1.61-1.69%, Cr 0.14-0.18%, Ni 0.11-0.16%, Cu 0.01-0.08%, Mo 0.09-0.13%, Nb 0.051-0.065%, Ti 0.011-0.019%, Al 0.021-0.049%, P 0.0090-0.0140%, S 0.0010-0.0038%, N 0.0021-0.0051%, and the rest is iron and inevitable impurities.

[0300] The steel plate with the chemical composition is suitable for the preparation of pipeline steel of X80 strength grade.

[0301] The obtained steel plate has a complex phase microstructure of quasi-polygonal ferrite + acicular ferrite + bainite + tempered bainite, the area ratio of quasi-polygonal ferrite and acicular ferrite is 20-45%, and the area ratio of bainite + tempered bainite is 55-80%; and the MA proportion in bainite is ≤30%, and the MA self-tempering decomposition proportion is ≥30%.

[0302] Here, the microstructure of the steel plate can be obtained by microstructure detection according to GB / T 15125-2009 "Metallic Materials - Specimens and Methods of Mechanical Testing".

[0303] Furthermore, the average grain size of ferrite of the obtained steel plate is 3-6 μm.

[0304] In terms of mechanical strength, the yield strength R t0.5 of the obtained steel plate is ≥550 MPa, the tensile strength R m is ≥660 MPa, the elongation A 50 is ≥30%, the yield strength ratio is ≤0.85; the yield strength difference of the same plate is ≤40 MPa; and among 1000 steel plate products, more than 90% of the number of steel plates have a yield strength difference of different plates ≤70 MPa, and more than 98% of the number of steel plates have a yield strength difference of different plates ≤90 MPa.

[0305] Here, the mechanical property detection can be carried out according to GB / T 228.1-2021 "Metallic Materials - Tensile Testing - Part 1: Room Temperature Test Methods".

[0306] In terms of low temperature toughness, the impact energy KV2 of the obtained steel plate at -20℃ is ≥320 J, the impact energy KV2 at -40℃ is ≥280 J, and the impact energy KV2 at -60℃ is ≥220 J.

[0307] Here, the low temperature toughness detection can be carried out according to GB / T 229-2007 "Metallic Materials Charpy Pendulum Impact Test Method".

[0308] In addition, the hardness of the obtained steel plate is ≤245 HV10.

[0309] The DWTT drop hammer shearing area percentage at -10℃ is 100%, the DWTT drop hammer shearing area percentage at -20℃ is ≥90%, and the DWTT ductile-brittle transition temperature is lower than -20℃.

[0310] In summary, compared with the prior art, the beneficial effects of the present application are: by taking point temperature measurement on the longitudinal full plate of the hot-rolled steel plate, and based on the temperature measurement results, under a series of data processing schemes, the cooling temperature control of the hot-rolled steel plate is realized, and on the one hand, the longitudinal full plate performance uniformity of each steel plate (i.e. the performance uniformity of the same plate is improved), on the other hand, the performance consistency of different steel plates is guaranteed, so that the performance uniformity of any two steel plates produced is improved, and thus the same plate strength difference and different plate strength difference are greatly reduced, the performance stability of the steel plate product is improved, and the heating-rolling-cooling process is adopted, without the need for additional time-consuming or long process procedures, and without the requirement of high alloy content of chemical composition, the production efficiency is high and the production cost is low.

Claims

1. A method of producing a steel sheet, characterized by, The production method comprises: heating a billet with a thickness of ≤320 mm in a heating furnace, after exiting the heating furnace, the billet is firstly rolled in a recrystallization zone and then rolled in a non-recrystallization zone to obtain a hot-rolled steel plate with a longitudinal length D and a thickness t; wherein t is valued at 6-30 mm; temperature measurement is performed on points taken from the head to the tail of the hot-rolled steel plate at intervals of 0.2-0.5 m in the longitudinal direction to obtain a temperature measurement result; The temperature of the temperature measuring point in the D T ~(D-D W ) region in the longitudinal direction is used to calculate the middle average temperature T Z ; the steel sheet head section is set as a head low temperature section, the temperature of which is lower than T Z -T T the steel sheet tail section is set as a tail low temperature section, the temperature of which is lower than T Z -T W and the rest section except the head low temperature section and the tail low temperature section is set as a middle section; wherein T T and T W each takes any value in the range of 20-50℃. the head low-temperature section is divided into first-n sub-sections arranged in sequence from the head to the tail according to the measured temperature from low to high, and the tail low-temperature section is divided into first-m sub-sections arranged in sequence from the tail to the head according to the measured temperature from low to high, n≥2, m≥2; the hot-rolled steel plate enters an ultra-fast cooling system for water cooling; during this period, the unit length cooling water quantity Q of the middle section is taken as a standard, the unit length cooling water quantity of the first-n sub-sections of the head low-temperature section is controlled to increase in turn and be less than Q, and the unit length cooling water quantity of the first-m sub-sections of the tail low-temperature section is controlled to increase in turn and be less than Q; after exiting the ultra-fast cooling system, the steel plate is naturally air-cooled to room temperature on a cooling bed to obtain a steel plate product.

2. The method of producing a steel sheet according to claim 1, characterized by, the transverse width W of the hot-rolled steel plate; in the step of "temperature measurement is performed on points taken from the head to the tail of the hot-rolled steel plate at intervals of 0.2-0.5 m in the longitudinal direction", the points are taken in the transverse middle region W / 3-2W / 3 of the hot-rolled steel plate, and all the temperature measurement points are arranged in a straight line in the longitudinal direction.

3. The method of producing a steel sheet according to claim 1, characterized by, Step "calculating the average temperature T T ~(D-D W ) region in the longitudinal direction, to calculate the average temperature T Z " in the middle The temperature of the temperature measurement point in the D T ~(D-D W ) region in the longitudinal direction is summed and averaged to obtain the middle average temperature T Z ; D T D W D 4. The method of producing a steel sheet according to claim 1, characterized by, D T and D W have the same or different values, T T and T W have the same or different values, n and m have the same or different values.

5. The method of producing a steel sheet according to claim 1, characterized by, D T and D W The values of D and D decrease stepwise with increasing t.

6. The production method of the steel plate according to claim 5, characterized in that, when t has a value < 10 mm, 2.75 m < D T ≤ 3.5 m, 2.75 m < D W ≤ 3.5 m; when 10 mm < t < 15 mm, 2.25 m < D < 2.75 m T when 10 mm < t < 15 mm, 2.25 m < D < 2.75 m W when 10 mm < t < 15 mm, 2.25 m < D < 2.75 m 1.5m < D when 15mm < t < 30mm T 1.5m < D when 15mm < t < 30mm W 1.5m < D when 15mm < t < 30mm 7. The method of producing a steel sheet according to claim 1, characterized by, Step "Take the temperature below T" Z -T T The head section of the steel plate is designated as the low-temperature head section, with a temperature lower than T. Z -T W The section at the tail of the steel plate is designated as the tail low-temperature section, and the remaining sections, excluding the head and tail low-temperature sections, are designated as the middle section. the head low-temperature section and the middle section are divided by one temperature measurement point as a division boundary, and the tail low-temperature section and the middle section are divided by one temperature measurement point as a division boundary.

8. The method of producing a steel sheet according to claim 7, characterized by, Step "lowering the temperature below T Z -T T of the head section of the steel sheet as a head low-temperature section, lowering the temperature below T Z -T W of the tail section of the steel sheet as a tail low-temperature section, and the remaining section other than the head low-temperature section and the tail low-temperature section as a middle section" in the above-described steel sheet manufacturing method: When the temperature of the temperature measuring point close to the head of the steel plate is less than T Z -T T , and the temperature of the temperature measuring point far from the head of the steel plate reaches T Z -T T , the head low-temperature section and the middle section arranged longitudinally are divided by one of the two adjacent temperature measuring points. When, in the longitudinal direction of the steel plate, from the tail, the temperature of one of the two adjacent temperature measuring points near the tail is less than T Z -T W , and the temperature of the other temperature measuring point away from the tail reaches T Z -T W , then one of the two adjacent temperature measuring points is taken as the division boundary to divide the tail low-temperature section and the middle section arranged longitudinally.

9. The method of producing a steel sheet according to claim 1, characterized by, Step "lowering the temperature below T Z -T T of the head section of the steel sheet as a head low-temperature section, lowering the temperature below T Z -T W of the tail section of the steel sheet as a tail low-temperature section, and the remaining section other than the head low-temperature section and the tail low-temperature section as a middle section" in the above-described steel sheet manufacturing method: According to the temperature measurement result, a temperature curve of the full length of the steel plate in the longitudinal direction is fitted with temperature as the dependent variable and position as the independent variable; the position D corresponding to T Z -T T the position D corresponding to T TF the position D corresponding to T Z -T W the position D corresponding to T WF ; at the position D TF and the position D WF The steel plate is divided into a head low-temperature section, a middle section and a tail low-temperature section arranged in sequence from head to tail in the longitudinal direction by the division boundary.

10. The method of producing a steel sheet according to claim 1, characterized by, in the step of "the head low-temperature section is divided into first-n sub-sections arranged in sequence from the head to the tail according to the measured temperature from low to high, and the tail low-temperature section is divided into first-m sub-sections arranged in sequence from the tail to the head according to the measured temperature from low to high, n≥2, m≥2", the temperature curve is fitted according to the temperature measurement result with temperature as the dependent variable and position as the independent variable; According to the temperature span of each sub-section not exceeding T Tk dividing the head low-temperature section into n sub-sections; According to the temperature span of each sub-section does not exceed T Wk The tail low-temperature section is divided into m sub-sections; wherein T Tk is the difference between the maximum temperature T T1 and the minimum temperature T T0 in the head low temperature section, T T1 -T T0 / n, or the maximum temperature T Z -T T and the minimum temperature T T0 ’ in the head low temperature section, T Z -T T -T T0 / n, or the temperature span predetermined value T n ; T Wk the highest temperature T W1 and the lowest temperature T W0 of the tail low-temperature section, or the difference T W1 -T W0 of 1 / m, or the highest temperature T Z -T W of the tail low-temperature section, or the difference T W0 -T Z -T W -T W0 of 1 / m, or the temperature span predetermined value T m ; in the step of "the head low-temperature section is divided into first-n sub-sections arranged in sequence from the head to the tail according to the measured temperature from low to high, and the tail low-temperature section is divided into first-m sub-sections arranged in sequence from the tail to the head according to the measured temperature from low to high, n≥2, m≥2", in the first-n sub-sections of the head low-temperature section, two adjacent sub-sections are divided by one temperature measurement point as a division boundary; T n and T m each value is selected from any value in the range of 5 to 20 °C.

11. The method of producing a steel sheet according to claim 10, characterized by, in the first-m sub-sections of the tail low-temperature section, two adjacent sub-sections are divided by one temperature measurement point as a division boundary. in the step of "the head low-temperature section is divided into first-n sub-sections arranged in sequence from the head to the tail according to the measured temperature from low to high, and the tail low-temperature section is divided into first-m sub-sections arranged in sequence from the tail to the head according to the measured temperature from low to high, n≥2, m≥2", ​ 12. The method of producing a steel sheet according to claim 11, characterized by, ​ From the first temperature measuring point of the low-temperature section of the head portion, when the temperature of the temperature measuring point close to the head portion of the adjacent two temperature measuring points is not more than T Tk from the lowest temperature section of the sub-section, and the temperature of the temperature measuring point far from the head portion exceeds T Tk from the lowest temperature section of the sub-section, the temperature measuring point close to the head portion is taken as the division boundary to divide the sub-section and the next sub-section. From the first temperature measuring point near the tail end of the low temperature section of the tail, when the temperature of the temperature measuring point near the tail end of the adjacent two temperature measuring points is not more than T Wk from the lowest temperature section of the sub-section, and the temperature of the temperature measuring point away from the tail end exceeds T Wk from the lowest temperature section of the sub-section, then the temperature measuring point near the tail end is divided as a division boundary to divide the sub-section and the next sub-section.

13. The method of producing a steel sheet according to claim 1, characterized by, In the step of "water-cooling the hot-rolled steel plate in the ultra-fast cooling system to a final cooling temperature of 210-530℃, during which, taking the unit length cooling water quantity Q of the middle section as a standard, the unit length cooling water quantity of the first-nth sub-section of the head low-temperature section is controlled to increase successively and be less than Q, and the unit length cooling water quantity of the first-mth sub-section of the tail low-temperature section is controlled to increase successively and be less than Q", The unit length cooling water quantity of the first to nth sub-sections is respectively k1 to kn times of Q n ; wherein, k1 to kn n are valued from 0.55 to 0.98; The unit length cooling water quantity of the first to mth sub-sections is K1 to K m times of Q respectively; wherein, K1 to K m are valued from 0.50 to 0.

95.

14. The method according to claim 13, characterized in that the steel plate is a pipeline steel, the billet is heated in a heating furnace, the soaking section temperature is 1150-1220℃, and the residence time is 25-45min. When n≥3, k1~k n Set to arithmetic progression; K1~Km-1 are set to be equal difference increasing when m≥3. m are set to be equal difference increasing.

15. The method of producing a steel sheet according to claim 13, characterized by, k1~k n the values of K1~K m increase with the increase of t.

16. The method of producing a steel sheet according to claim 15, characterized by, When t is less than 10 mm, k1~k n The value ranges from 0.55 to 0.85; when 10mm ≤ t < 15mm, k1 ~ k n The value ranges from 0.70 to 0.90; when 15mm ≤ t ≤ 30mm, k1 ~ k n The value ranges from 0.80 to 0.98; When t is less than 10 mm, K1~K m The value ranges from 0.50 to 0.80; when 10mm ≤ t < 15mm, K1 ~ K m The value ranges from 0.65 to 0.85; when 15mm ≤ t ≤ 30mm, K1~K m The value ranges from 0.75 to 0.

95.

17. The method of producing a steel sheet according to claim 13, characterized by, When t is <10mm, n=m=3, k1 is 0.55-0.65, k2 is 0.65-0.75, k3 is 0.75-0.85, K1 is 0.50-0.60, K2 is 0.60-0.70, and K3 is 0.70-0.80; When 10mm≤t<15mm, n=m=3, k1 is 0.70-0.80, k2 is 0.80-0.85, k3 is 0.85-0.90, K1 is 0.65-0.75, K2 is 0.75-0.80, and K3 is 0.80-0.85; When 15mm≤t≤30mm, n=m=3, k1 is 0.80-0.87, k2 is 0.87-0.92, k3 is 0.92-0.98, K1 is 0.75-0.85, K2 is 0.85-0.90, and K3 is 0.90-0.

95.

18. The method of producing a steel sheet according to claim 1, characterized by, In the step of "taking points on the hot-rolled steel plate along the longitudinal direction at intervals of 0.2-0.5m from the head to the tail to measure the temperature": Taking points on the hot-rolled steel plate along the longitudinal direction at intervals of 0.2-0.5m from the head to the tail to measure the temperature; Removing outliers.

19. The method of producing a steel sheet according to claim 18, characterized by, In the step of "removing outliers": If the temperature difference between the temperature of a temperature measuring point and the temperature of an adjacent temperature measuring point reaches T X1 , the temperature measuring point is the abnormal value; wherein, T X2 is valued at 60-80℃, and T X2 is valued at 5-15℃. X1 ​ Or, if the temperature of a temperature measurement point and the difference between the temperatures of the adjacent two temperature measurement points reach T X3 The above, then the temperature measurement point is the abnormal value; wherein, T X3 60~80℃; Or, based on all temperature measuring points, a temperature curve of the whole length of the steel plate is fitted with temperature as the dependent variable and position as the independent variable, and if the temperature of a temperature measuring point deviates from the temperature curve by T X4 above, it is determined that the temperature measuring point is an abnormal value and is removed; wherein, T X4 is valued at 60-80℃.

20. The method of producing a steel sheet according to claim 1, characterized by, The steel plate is a pipeline steel, the billet is heated in a heating furnace, the soaking section temperature is 1150-1220℃, and the residence time is 25-45min. When rolling in the recrystallization zone, the rolling temperature is 950-1050℃, and an intermediate billet with a thickness of 2t-6t is obtained. When rolling in the non-recrystallization zone, the rolling temperature is 750-850℃. When water-cooling in the ultra-fast cooling system, the final cooling temperature is 210-530℃.

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