A method for producing a hot-rolled steel sheet

Abstract

The application provides a preparation method of a hot-rolled steel plate, comprising the following steps: S10, providing a roller with a good oxidation film; S20, performing finish rolling on a steel plate to be finished rolled under the condition that the roller has the good oxidation film; and S30, cooling and coiling the steel plate after the finish rolling to obtain the hot-rolled steel plate. In the technical scheme of the application, the steel plate is finish rolled by using the roller with the good oxidation film, the three times of iron oxide scale pressing in during the finish rolling are prevented by preventing the oxidation film on the roller surface from peeling off, and thus the hot-rolled steel plate with good surface quality is obtained. Meanwhile, the technical scheme of the application is particularly suitable for the production of 2.5-3 mm high-strength IF steel plates containing phosphorus, realizes stable and efficient production of the high-strength IF steel plates containing phosphorus, and improves the production efficiency and reduces the production cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel plate production, in particular to a preparation method of hot-rolled steel plate. BACKGROUND

[0002] The problem of poor surface quality of hot-rolled steel plate caused by the third oxide skin pressing into the steel plate has been widespread in the technical field of steel plate production, and the problem is most serious for high-strength IF steel containing P. In the production practice of this series of steel, serious pepper-and-salt-shaped oxide skin defects (as shown in the attached Figure 1 , 2 The defects are caused by the third oxide skin pressing into the steel plate in the finishing process, and the third oxide skin also damages the oxide film on the roll (as shown in the attached Figure 3 ), which causes the continuously produced rough surface defects of the steel plate in the subsequent production of the roll.

[0003] In the prior art, the method for controlling the third oxide in the finishing process is to reduce the finishing entry temperature and the finishing temperature, but for some steel materials with high phase transition temperature, reducing the finishing entry temperature and the finishing temperature will lead to rolling breakage or even scrap steel. SUMMARY

[0004] The present application provides a preparation method of hot-rolled steel plate to solve the problem of reduced surface quality of hot-rolled steel plate caused by the third oxide skin pressing into the steel plate in the finishing process.

[0005] The present application provides a preparation method of hot-rolled steel plate, which comprises the following steps:

[0006] S10: providing a roll with a good oxide film;

[0007] S20: finishing the steel plate to be finished under the condition that the roll has a good oxide film;

[0008] S30: cooling and coiling the finished steel plate to obtain the hot-rolled steel plate.

[0009] In the technical solution of the present application, the roll with a good oxide film is used to finish the steel plate, which prevents the oxide film on the roll surface from peeling off, on the one hand, to prevent the peeled oxide film on the roll surface from adhering to the surface of the hot-rolled steel plate and causing the third oxide skin defect to be pressed into the steel plate, and on the other hand, to prevent the uneven roll surface from causing the steel plate to be re-oxidized after the oxide film on the roll surface peels off, and the iron skin pressed into the steel plate together with the iron skin broken by the furrow. Therefore, the method can prevent the third oxide skin from being pressed into the steel plate in the finishing process, so that the hot-rolled steel plate with good surface quality can be obtained.

[0010] In some embodiments of the present application, the step S10 specifically comprises:

[0011] The rolling is performed using a hot rolling material and / or a transition material so that the roll surface has a good oxidation film.

[0012] In some embodiments of the present application, in the step S10, the rolling distance of the rolling performed using the hot rolling material and / or the transition material is 15-25 km.

[0013] In some embodiments of the present application, in the step S20, in the finish rolling process, the steel plate to be finish rolled is a high-strength IF steel plate containing phosphorus with a thickness of 2.5-3 mm, and the maximum thickness jump is ≤0.3 mm.

[0014] In some embodiments of the present application, in the step S20, in the finish rolling process, the thickness of the steel plate to be finish rolled is reduced from large to small, and

[0015] when 2.8

[0016] when 2.6

[0017] when 2.5

[0018] wherein a is the thickness of the steel plate to be finish rolled, in mm.

[0019] Optionally, in the finish rolling process, the finish rolling gap time of each steel plate to be finish rolled is 40-60 s.

[0020] In some embodiments of the present application, in the step S20, in the finish rolling process, the finish rolling entry temperature is 1045-1115℃, and the finish rolling final temperature is 900-940℃.

[0021] In some embodiments of the present application, in the step S20, in the finish rolling process,

[0022] when 2.8

[0023] when 2.6

[0024] when 2.5

[0025] wherein a is the thickness of the steel plate to be finish rolled, in mm.

[0026] In some embodiments of the present application, in the step S30, in the cooling process, a front-stage concentrated cooling is used.

[0027] In some embodiments of the present application, in the step S30, the coiling temperature is 660-700°C.

[0028] In some embodiments of the present application, in the step S20, the residual water on the surface of the steel plate to be finish-rolled is removed by using high-pressure air blowing from the side and from the top simultaneously during the finish-rolling process. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the present application.

[0030] Figure 1 is a morphology diagram of the medium-oxidized scale pressed-in defect of the high-strength IF steel plate containing phosphorus.

[0031] Figure 2 is a morphology diagram of the heavy-oxidized scale pressed-in defect of the high-strength IF steel plate containing phosphorus.

[0032] Figure 3 is a morphology diagram of the oxide film peeling of the finish-rolling work roll.

[0033] Figure 4 is an automobile rear floor assembly obtained by stamping the high-strength IF galvanized steel plate containing phosphorus prepared from the high-strength IF steel plate containing phosphorus prepared in Example 1 after cold rolling and hot galvanizing.

[0034] Figure 5 is an automobile A-pillar reinforcement obtained by stamping the high-strength IF galvanized steel plate containing phosphorus prepared from the high-strength IF steel plate containing phosphorus prepared in Example 1 after cold rolling and hot galvanizing.

[0035] The specific embodiments of the present application have been shown and described in the foregoing drawings and specification, and it will be apparent to those skilled in the art that various modifications can be made in the present application without departing from the scope of the present application. These modifications should be understood as falling within the scope of the present application. DETAILED DESCRIPTION

[0036] Each of the embodiments or implementations in the present specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments.

[0037] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the implementation or example are included in at least one implementation or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same implementation or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more implementations or examples as appropriate.

[0038] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified.

[0039] The inventors found that during the production of hot-rolled steel plates, during the finish rolling process, the generated three times of oxide skin of the steel plate is pressed to cause the generation of pepper salt type oxide skin on the surface of the hot-rolled steel plate. The three times of oxide skin is mainly distributed in the form of fine and sand-like on the surface of the hot-rolled steel plate, and after pickling, it leaves pinhole-like small pits with different depths on the surface of the steel plate, which seriously affects the surface quality of the hot-rolled steel plate.

[0040] Especially for high-strength IF steel plates containing phosphorus, because the phase transition temperature is relatively high, using the traditional method of reducing the finish rolling temperature and the finishing temperature to control the generation of three times of oxide skin is not conducive to the stability of the steel plate rolling, and may cause rolling breakage or even scrap steel, so it is necessary to control the pressing of three times of oxide skin from other conditions of finish rolling.

[0041] To this end, the present application provides a preparation method of a hot-rolled steel plate, comprising the following steps:

[0042] S10: providing a roller with a good oxide film;

[0043] S20: under the condition that the roller has a good oxide film, finish rolling the steel plate to be finish rolled;

[0044] S30: cooling and coiling the steel plate after finish rolling to obtain the hot-rolled steel plate.

[0045] In the technical solution of the present application, the steel plate is finished rolling by using the roll with good oxide film, and the roll surface oxide film peeling is prevented, on the one hand, to prevent the peeled roll surface oxide film from adhering to the hot-rolled steel plate surface and causing the third oxide scale defect to be pressed into the steel plate, and on the other hand, to prevent the uneven roll surface from causing the steel plate to be re-oxidized after the roll surface oxide film peels off and the scale broken by the furrow to be pressed into the steel plate. Therefore, the third oxide scale pressed in during the finishing rolling process is prevented by the method, and a hot-rolled steel plate with good surface quality is obtained.

[0046] In some embodiments of the present application, step S10 specifically comprises:

[0047] The rolling is performed using the hot-rolling material and / or the transition material to make the roll surface have a good oxide film.

[0048] In some embodiments described above, before the target steel plate is finished rolling, the hot-rolling mill is used to roll the hot-rolling material and / or the transition material. Since the hot-rolling mill is unstable when it is started to be used, the hot-rolling material is used to make the hot-rolling mill enter a thermal stable state, and the roll is expanded by heat to reach a predetermined roll gap, which prepares for the finishing rolling of the target steel plate. At the same time, in order to meet the rolling requirements of the target steel plate, a certain transition material is required to make a transition between the hot-rolling material and the target steel plate, which is mainly used to complete the width, thickness and hardness jumps between the two, so as to ensure the transition from one stable state to another. In addition, the roll surface of the hot-rolling mill can form a complete oxide film. When the roll surface oxide film is formed, the target steel plate is finished rolling, which can effectively prevent the third oxide scale from being pressed in due to the instability of the roll oxide film.

[0049] In some embodiments described above, the hot-rolling material and the transition material can be reasonably selected according to the width, thickness and hardness of the target steel plate. Generally, the width jump of the hot-rolling material and the transition material follows the tortoise shell rolling plan, and the thickness jump generally follows the transition from thick to thin. Common hot-rolling materials and transition materials include DX51D, DR01 and other CQ grade steel plates.

[0050] In some embodiments of the present application, in step S10, the rolling mileage of the hot-rolling material and / or the transition material is 15-25 km.

[0051] In some embodiments described above, the rolling mileage of the hot-rolling material and / or the transition material is 15-25 km, which is to ensure the stability of the rolling jump by using a sufficient amount of hot-rolling material and transition material, so as to further strengthen the oxide film on the roll surface, so that the oxide film on the roll surface is not easy to fall off when the target steel plate is finished rolling, thereby effectively avoiding the third oxide scale from being pressed in.

[0052] In some embodiments of the present application, in step S20, during the finishing rolling process, the steel plate to be finished rolling is a high-strength IF steel plate with phosphorus and with a thickness of 2.5-3 mm, and the maximum thickness jump between adjacent two plates is less than or equal to 0.3 mm.

[0053] In some embodiments described above, the steel plate to be finished rolling is limited to a high-strength IF steel plate with phosphorus and with a thickness of 2.5-3 mm. As indicated in the background section of the present application, since the high-strength IF steel plate with phosphorus has a relatively high phase transition temperature, it is not suitable to prevent the penetration of the iron oxide scale by reducing the finishing rolling entry temperature and the finish rolling temperature. In addition, the IF steel plate is an ultra-low carbon steel, and phosphorus is also a strong oxidizing element, which is easy to be oxidized. Moreover, the strength of the IF steel plate is higher than that of the conventional ultra-low carbon steel. On the other hand, 2.5-3 mm belongs to the rolling of thin-gauge steel plates, and the rolling pressure per unit length is also greater, and the finishing rolling time is longer, which makes the steel plate more prone to oxidation. Therefore, the finishing rolling process of the 2.5-3 mm high-strength IF steel plate with phosphorus is a difficulty in the prior art.

[0054] In some embodiments described above, for the 2.5-3 mm high-strength IF steel plate with phosphorus, the maximum thickness jump between adjacent two plates should be ensured to be less than or equal to 0.3 mm, which is beneficial to the smooth transition of the hot rolling of thin-gauge steel plates and the generation and maintenance of the oxidation film on the roll surface. The good oxidation film on the roll surface can effectively control the generation of the penetration of the iron oxide scale during the finishing rolling process.

[0055] In some embodiments of the present application, in step S20, during the finishing rolling process, the thickness of the steel plate to be finished rolling is from large to small, and the maximum thickness jump between adjacent two plates is less than or equal to 0.3 mm.

[0056] When 2.8

[0057] When 2.6

[0058] When 2.5

[0059] Wherein, a is the thickness of the steel plate to be finished rolling, in mm.

[0060] Optionally, the finishing rolling gap time of each steel plate to be finished rolling is 40-60 s during the finishing rolling process.

[0061] In some embodiments described above, the maximum thickness jump of the steel plates with different thicknesses during the finishing rolling process is further limited. The smaller the thickness of the steel plate is, the smaller the corresponding maximum thickness jump is, which can more effectively ensure the stability of the target steel plate during the rolling process, thereby preventing the damage to the oxidation film on the roll and further preventing the penetration of the iron oxide scale. It should be noted that the thickness jump refers to the thickness difference between the previous steel plate and the adjacent next steel plate during the finishing rolling process.

[0062] Further, in the finishing process, the finishing gap time of each steel plate to be finished is controlled to be 40-60s, which is longer than the finishing gap time in the prior art. The advantage is also to slow down the finishing speed of the thin gauge steel plate, to make the finishing process more stable, to control the finishing rhythm, and to further reduce the damage to the oxide film of the roll.

[0063] In some embodiments of the present application, in step S20, in the finishing process, the finishing entry temperature is 1045-1115℃, and the finishing final rolling temperature is 900-940℃.

[0064] In some embodiments described above, different from the prior art, for the finishing of the high-strength IF steel plate containing phosphorus, by controlling a higher finishing entry temperature, it can be ensured that the 2.5-3mm high-strength IF steel plate containing phosphorus will not appear the problem of rolling breakage in the finishing process. In addition, by appropriately reducing the final rolling temperature, the coiling temperature of the target steel plate can be greatly reduced, thereby being more conducive to the control of the iron oxide scale in the finishing and coiling processes.

[0065] In some embodiments of the present application, in step S20, in the finishing process,

[0066] When 2.8

[0067] When 2.6

[0068] When 2.5

[0069] Wherein, a is the thickness of the steel plate to be finished, in mm.

[0070] In some embodiments described above, the finishing entry temperature of the high-strength IF steel plate containing phosphorus with different thicknesses is further limited. For the thinner steel plate, the finishing entry temperature is higher. The same is to ensure the stability of the thin gauge high-strength IF steel plate containing phosphorus in the finishing process, to prevent the phenomenon of rolling breakage or even scrap.

[0071] In some embodiments of the present application, in step S20, in the finishing process, the finishing speed system of each steel plate to be finished is: at a speed of 9-11m / s, then at a speed of 0.1-0.2m / s 2 After accelerating to 11-13m / s, keep uniform speed to coiling, then at a speed of 0.1-0.2m / s 2 After accelerating to 16-20m / s, keep uniform speed to F1 tail throwing, then at a speed of -0.4--0.5m / s 2 Accelerate to 15-16m / s to throw the tail.

[0072] In some of the above embodiments, in order to balance the stability and surface quality of finishing rolling, a finishing rolling speed process was customized, adopting a strategy of low-speed threading, two-stage acceleration, high-speed rolling, and low-speed steel removal. Low-speed threading can ensure the stability of subsequent coiling bite, the second acceleration maintains uniform rolling until coiling is stable, and then the second acceleration is accelerated to a higher rolling speed, and then uniform rolling is maintained until F1 tail removal, and then deceleration is reduced to remove the tail. This rolling speed process can ensure the stability and surface quality of finishing rolling, as well as the efficiency of finishing rolling.

[0073] In some embodiments of this application, during step S30, front-end centralized cooling is used in the cooling process.

[0074] In some of the above embodiments, a front-end centralized cooling method is adopted to reduce the contact time between the steel plate and air after finishing rolling. This helps to reduce the formation of insoluble iron oxide and magnetite in the iron oxide scale after finishing rolling, and achieves the effect of reducing the thickness of the iron oxide scale.

[0075] In some embodiments of this application, during step S30, the winding temperature is 660–700°C.

[0076] In some of the above embodiments, by reducing the finishing rolling temperature, the coiling temperature of the steel plate after finishing rolling is further reduced under the same cooling conditions. The lower coiling temperature can reduce the production of iron oxide scale during the coiling process, thereby further improving the surface quality of the steel plate.

[0077] In some embodiments of this application, in step S20, during the finishing rolling process, high-pressure air from both side spray and longitudinal spray is used to remove residual water from the surface of the steel plate to be finished rolled.

[0078] In some of the above embodiments, as shown in the appendix Figure 4 As shown, compared to the prior art, which only uses longitudinal high-pressure air to remove residual water from the surface of the steel plate to be finished during finishing rolling, some embodiments of this application add a side-spray high-pressure air device at the entrance of the finishing mill stand. During the finishing rolling process, both side-spray and longitudinal high-pressure air are used to remove residual water from the surface of the steel plate to be finished, reducing the contact oxidation of the plate surface with residual water during the finishing rolling process.

[0079] In some embodiments of this application, the method for preparing hot-rolled steel sheets further includes the following steps:

[0080] A fan is used to accelerate the cooling of the hot-rolled steel sheet after the coiler. The hot-rolled steel sheet is either directly fed into the cold rolling mill or placed on a low-temperature substrate.

[0081] In some of the above embodiments, the oxide scale layer formed at high temperature before coiling of the hot-rolled steel sheet is composed of an outer layer of thin Fe2O3, an intermediate layer of Fe3O4, and an innermost layer of FeO. The FeO is still thermodynamically unstable and will undergo eutectoid reaction when the temperature is high after coiling:

[0082] 4Fe 1-y O→Fe3O4+(1-4y)Fe

[0083] Finally, the eutectoid oxide scale layer has the following structure: a small amount of Fe2O3 on the outer layer, Fe3O4 in the intermediate layer, eutectoid structure Fe3O4+Fe in the bottom layer, and a small amount of residual FeO. The eutectoid oxide scale structure is not easy to remove during cold rolling and pickling, thereby affecting the subsequent processing and application of the hot-rolled steel sheet, such as reducing the surface quality of the finished steel sheet after cold rolling.

[0084] In some embodiments of the present application, the following steps are further included:

[0085] The slab obtained by continuous casting is subjected to a heating treatment;

[0086] The heated slab is subjected to rough phosphorus removal by high-pressure water;

[0087] The slab after rough phosphorus removal is subjected to rough rolling to obtain a rough-rolled slab;

[0088] The rough-rolled slab is subjected to head and tail cutting, and then subjected to fine phosphorus removal by high-pressure water to obtain a steel sheet to be finished rolling.

[0089] In some of the above embodiments, the steel sheet to be finished rolling obtained by rough rolling phosphorus removal has better surface quality, which can provide a basis for obtaining hot-rolled steel sheets with good surface quality.

[0090] Hereinafter, the preparation method of the hot-rolled steel sheet of the present application will be described in more detail by way of examples, but the present application is by no means limited to these examples.

[0091] Example 1

[0092] The 2.5-3 mm phosphorus-containing high-strength IF steel sheet (grade: H220YD) of the Liansteel 2250 hot-rolling production line includes the following steps: slab heating→high-pressure water rough scale removal→rough rolling→head and tail cutting→high-pressure water fine scale removal→finish rolling→laminar cooling→coiling→packing, printing→warehousing.

[0093] Among them, the temperature schedule of the phosphorus-containing high-strength IF steel sheet in the above steps is shown in Table 1;

[0094] In the finish rolling step, the specific rolling plan is shown in Table 2;

[0095] The rolling gap time of the hot-rolled steel sheet and the transition material is 30 s, and the finish rolling gap time of the main rolling material is 50 s;

[0096] The high-pressure air of the newly added side spray device at the entrance of the finishing rolling F1-F7 stands is opened to blow the upper and lower surfaces of the steel plate to remove residual water;

[0097] The finishing rolling speed schedule of each main rolling material is as follows: the threading speed is 10.95 m / s, then the speed is increased by 0.12 m / s 2 After accelerating to 11.35 m / s, the speed is kept constant until the coiling is stable, then the speed is increased by 0.126 m / s 2 to 17 m / s, the speed is kept constant until the F1 tailing is finished. The speed is decreased by -0.435 m / s 2 to 15.75 m / s for tailing;

[0098] The cooling water between the finishing rolling stands is feedback controlled, and the water amount is adjusted in real time according to the finishing rolling final rolling temperature of the steel strip to ensure that the finishing rolling final rolling temperature is stably hit;

[0099] In the laminar cooling step, the front concentrated cooling mode is adopted;

[0100] When the 2.5-3 mm phosphorus-containing high-strength IF steel plate is coiled, the fan beside the walking beam is opened to accelerate the cooling of the steel plate after the coiling machine, and the offline steel plate is directly sent to the cold rolling or placed in the low-temperature base plate storage area.

[0101] Table 1

[0102]

[0103] Table 2

[0104]

[0105] Test Example 1

[0106] The performance of the 2.5 mm H220YD steel coil at the tail 100 m of the produced steel coil in Example 1 is tested by offline sampling, 3 groups of tests are performed on the WAW-300 microcomputer electro-hydraulic servo testing machine using 360 mm*25 mm*2.5 mm H220YD samples, and the specific data are shown in Table 3:

[0107] Table 3

[0108] Sample No. Tensile strength / MPa Yield strength / MPa Elongation A80 / % 1 358 218 35.5 2 362 225 34.5 3 359 220 36.0 Average 360 221 35.3 Control plan requirements ≥310 ≥190 31.0

[0109] From the results in Table 3, it can be seen that the various performances of the hot-rolled phosphorus-containing high-strength IF steel plate prepared by the technical scheme of the present application all meet the quality control requirements, the tensile strength, yield strength and elongation A80 all exceed the relevant requirements, which shows that the technical scheme of the present application can prevent the iron oxide scale from being pressed in, can ensure the surface quality of the phosphorus-containing high-strength IF steel plate, and can also ensure that the mechanical properties meet the quality requirements, which is suitable for industrial production.

[0110] Test Example 2

[0111] The 2.5 mm phosphorus-containing high-strength IF steel plate prepared in Example 1 was cold-rolled and hot-dip galvanized, and the performance of the phosphorus-containing high-strength IF galvanized steel plate was tested. On a 105DP-A Wanzheng 10T testing machine, 3 groups of different width specifications of finished product performance and surface quality were tested, and the specific data are shown in Tables 4 and 5:

[0112] Table 4

[0113]

[0114]

[0115] Table 5

[0116]

[0117] From the results in Tables 4 and 5, it can be seen that the product obtained by cold-rolling and hot-dip galvanizing the 2.5 mm phosphorus-containing high-strength IF steel plate prepared by the technical scheme of the present application also has good performance, and its mechanical properties meet the performance requirements of the customer delivery conditions, and also meets the higher surface quality requirements, which shows that the technical scheme of the present application can effectively reduce the iron oxide scale indentation of thin-gauge phosphorus-containing high-strength IF steel plate, and can realize stable and efficient production of 2.5-3.0 mm thick thin-gauge P-containing high-strength IF steel, improving production efficiency and reducing production cost.

[0118] As shown in Figure 4 , Figure 5 , they are all automobile reinforcing products formed by stamping the above-mentioned phosphorus-containing high-strength IF galvanized steel plate, Figure 4 is an automobile rear floor assembly, Figure 5 is an automobile A-pillar reinforcing plate, and it can be seen that these products all have good quality, which shows that the phosphorus-containing high-strength IF galvanized steel plate has good processing performance and surface quality, and further shows that the technical scheme of the present application, by controlling the production conditions of the phosphorus-containing high-strength IF steel plate, obtains a thin-gauge phosphorus-containing high-strength IF steel plate with mechanical properties and surface quality meeting the requirements.

[0119] Finally, it should be noted that: the above embodiments are only used to illustrate the technical scheme of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical scheme recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical scheme deviate from the scope of the technical scheme of the embodiments of the present application.

Claims

1. A method of producing a hot-rolled steel sheet, characterized by, The method comprises the following steps: S10: providing a roll with a good oxidation film, comprising: using a hot roll material and / or a transition material for rolling so that the roll surface has a good oxidation film; S20: under the condition that the roll has a good oxidation film, finish rolling a steel plate to be finished, wherein the steel plate to be finished is a high-strength IF steel plate containing phosphorus with a thickness of 2.5-3 mm, the thickness of the steel plate to be finished is rolled from large to small, the maximum thickness jump is ≤0.3 mm, the finish rolling entry temperature is 1045-1115℃, and the finish rolling final rolling temperature is 900-940℃; when 2.8 S30: cooling and coiling the finished steel plate to obtain the hot-rolled steel plate; in the cooling process, a front-stage concentrated cooling is used.

2. The production method according to claim 1, characterized by, In the step S10, the rolling distance of the rolling using the hot roll material and / or the transition material is 15-25 km.

3. The production method according to claim 1, characterized by, In the step S20, in the finish rolling process, wherein, when 2.8 when 2.6 when 2.5 wherein a is the thickness of the steel plate to be finished, in mm.

4. The method of claim 1, wherein, In the step S20, in the finish rolling process, the finish rolling gap time of each steel plate to be finished is 40-60 s.

5. The preparation method according to claim 1, characterized in that, In the step S30, in the coiling process, the coiling temperature is 660-700℃.

6. The method of claim 1, wherein, In the step S20, in the finish rolling process, high-pressure air is used to remove residual water on the surface of the steel plate to be finished simultaneously by side blowing and longitudinal blowing.

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