A rolling method of 1.2mm super-thin gauge hot-rolled patterned steel plate

Abstract

This invention discloses a rolling method for 1.2mm ultra-thin hot-rolled patterned steel plates in the field of hot-rolled steel production. The method includes the following steps: using ordinary carbon steel and controlling the thickness and length of the steel billet; heating using a hot-feeding and hot-charging method; performing rough rolling and finish rolling; laminar flow cooling of the finished steel plate; and finally coiling. This invention uses a slab of appropriate length, which helps reduce the temperature difference between the intermediate billet and the head and tail of the coil. The hot-feeding and hot-charging method increases the core temperature of the slab, facilitating stable rolling. Four passes of rough rolling further reduce the temperature drop at the finish rolling inlet. During finish rolling, by rationally controlling the rolling speed, plate crown, looper amount, bending roll force, and roll shifting amount, the resulting 1.2mm thick patterned plate has advantages such as good rolling stability, good pattern morphology, and excellent overall performance. It avoids defects such as rolled-off ends, waviness, and scrap in existing technologies, and can improve the yield of ultra-thin hot-rolled patterned plates.

Description

Technical Field

[0001] This invention relates to the field of hot-rolled steel production, and more particularly to a rolling method for a 1.2mm ultra-thin hot-rolled patterned steel plate. Background Technology

[0002] Currently, the standard thickness of patterned steel plates used in automobiles ranges from 2.0 to 6.0 mm. However, as the automotive industry gradually moves towards lightweighting and cost reduction, the demand for ultra-thin hot-rolled steel is increasing. Reducing the thickness of steel plates can decrease vehicle weight and carbon emissions, and can also replace cold-rolled plates, further reducing carbon emissions and saving production costs.

[0003] Existing technologies disclose several methods for producing extremely thin hot-rolled steel, such as:

[0004] CN113996665A discloses a production process for rolling extremely thin patterned steel plates from thin slabs, including slab heating, rough rolling, finish rolling, laminar flow cooling, and coiling. In the slab heating process, the slab thickness is selected as 90-105mm, the slab is centrally loaded into the furnace, and the overhang at both ends of the slab is controlled to be ≤700mm. The overall furnace time is controlled within 70-140 minutes; the first furnace temperature is controlled at 750-900℃; the second furnace temperature is controlled at 1050-1130℃, and the total furnace time for the first and second furnaces is controlled within 35-70 minutes; the temperature of the third furnace and soaking furnace sections is controlled in conjunction with the furnace time. Compared with existing technologies, this invention can utilize thin slabs to continuously and stably produce extremely thin patterned steel plates in batches.

[0005] CN112522566A discloses a method for selectively adding microalloying elements such as boron (B) to steel. During the smelting process, the basicity of the slag, the type and melting point of inclusions in the steel, the free oxygen content in the molten steel, and the content of acid-soluble aluminum (Als) are controlled. Then, a 1.5-3mm thick strip is cast using twin-roll thin-strip continuous casting. After exiting the crystallizing roll, the strip directly enters a closed chamber with a non-oxidizing atmosphere and is then hot-rolled on an online rolling mill under sealed conditions. The rolled strip is cooled using an air atomization cooling method, which effectively reduces the thickness of the oxide scale on the strip surface, improves the temperature uniformity, and enhances the surface quality. The final steel coil can be used directly as hot-rolled patterned plate / strip, or it can be used as finished patterned plate / strip after edge trimming and leveling.

[0006] CN104550256A discloses a method for controlling the shape of thin-gauge automotive structural steel plates using TMCP: The steel billet is heated to 1100–1200℃, with the temperature difference between the upper, middle, and lower layers controlled within 0–30℃; the rolling process parameters are kept constant, and rolling is performed using a rolling procedure set by a secondary model; the rolled steel plate undergoes ACC cooling, with the ACC roller speed set to 1.0–1.25 m / s, and the final cooling temperature controlled within the range of 400–500℃; after cooling, the steel plate is straightened online using an automatic straightening process with a secondary model, and the reheat temperature after straightening is controlled within 500–550℃.

[0007] CN113522967B discloses a method for controlling the shape of 550MPa grade wide-width thin-gauge automotive structural steel plates produced through a short-process rolling process. By controlling the slab thickness and wedge shape, controlling the load distribution of the finished strip, and controlling the convexity and straightness of the finished strip, this method solves the technical problems of low finishing efficiency and low overall yield caused by poor plate shape in 550MPa grade wide-width thin-gauge steel plates.

[0008] CN113522988B discloses a method for controlling the shape of thin-gauge automotive structural steel sheets using the DQ process, including full-process shape control encompassing rolling, cooling, leveling, and cross-cutting. This invention emphasizes a micro-wave compensation strategy during rolling. After rolling, a segmented cooling mode is adopted to primarily reduce the problem of poor sheet shape caused by excessive cooling rate after rolling. The steel coil is leveled immediately within 48 hours after rolling to avoid excessive work hardening and ensure a smooth surface. The flatness of the steel sheets produced using this method is between 5 and 8 mm / m, with an optimal flatness of 2 mm / m.

[0009] Although there are some existing technologies for producing patterned steel sheets for automobiles, many of them have high requirements for the composition of the billet, and the thickness of the steel sheets is mostly the traditional thickness, i.e., 2.0 to 6.0 mm. For extremely thin specifications, such as 1.2 mm patterned steel sheets, it is extremely difficult to produce them using existing rolling processes. It is not easy to ensure that the steel sheet thickness is uniform, the sheet shape is flat, and the pattern shape is complete at the same time, resulting in low production efficiency and low steel sheet yield. Summary of the Invention

[0010] To overcome the shortcomings of existing ultra-thin hot-rolled patterned steel plates, such as high production difficulty, low production efficiency, and low yield, the technical problem to be solved by this invention is to provide a rolling method for 1.2mm ultra-thin hot-rolled patterned steel plates that uses conventional carbon steel and conventional hot rolling mills to improve production efficiency and yield.

[0011] The technical solution adopted by this invention to solve its technical problem is:

[0012] A rolling method for an ultra-thin 1.2mm hot-rolled patterned steel plate, wherein the steel billet used for rolling is ordinary carbon steel, and the rolling process includes the following steps:

[0013] Step 1: Control the thickness of the steel billet to be 200-250mm and the length of the billet to be 8.5m-9.5m;

[0014] Step 2: The steel billet is loaded into the slab heating furnace using a hot charging method, and the slab exit temperature is 1220~1280℃.

[0015] Step 3: Rough rolling of the steel billet is carried out using two sets of rolling mills. The first set of rolling mills performs one pass, and the second set of rolling mills performs three passes. The inlet temperature of the rough rolling mill is 1160-1200℃, the outlet temperature of the rough rolling mill is 1120-1160℃, and the outlet speed of the rough rolling mill is 2-5m / s.

[0016] Step 4: Perform finish rolling on the intermediate billet obtained in Step 3. The finish rolling inlet temperature is 1060–1120℃, the finish rolling outlet temperature is 860–900℃, and the finish rolling outlet speed is 9.5–11.0 m / s. Control the thickness of the finished steel plate to 1.2 mm. During the finish rolling process, the number of cooling water groups between stands should not exceed 1, and the number of lubrication rolling groups should not be less than 3. The finish rolling mill includes 7 sets of finish rolling rolls, namely F1–F7, where F7 is a pattern roll, ensuring a pattern height ≥ 0.12 mm, and 6 sets of looper rolls, namely L1–L6. The finish rolling rolls and looper rolls are controlled according to the following requirements:

[0017] Crown of finishing rolls: F1: 10~25μm, F2: 5~10μm, F3: 3~9μm, F4: 2~6μm, F5: 1~4μm, F6: 1~3μm, F7: 1~3μm;

[0018] Finishing roll gap: F1: 15~20mm, F2: 5~15mm, F3: 2~8mm, F4: 2~5mm, F5~F7: 1~3mm;

[0019] Finishing roll speeds: F1: 0.8~1.0m / s, F2: 1.5~2.0m / s, F3: 2.0~3.5m / s, F4: 3.5~5.5m / s, F5: 5.5~8.0m / s, F6: 8.0~9.8m / s, F7: 9.5~11.0m / s;

[0020] Looping roller tension: L1: 600~750N / mm 2 L2: 750~850N / mm 2 L3: 850~950N / mm 2 L4: 1000~1300N / mm 2 L5: 1300~1600N / mm 2 L6: 1700~2000N / mm 2 ;

[0021] Bending force of finishing rolls: F1~F2: 80~200N / mm 2 F3~F4: 140~200N / mm 2 F5~F6: 100~120N / mm 2 F7: 40~80N / mm 2 ;

[0022] Finishing roll shifting amount: F1: 50~150mm, F2: -80~80mm, F3: -50~-50mm, F4: -40~40mm, F5:

[0023] -150~30mm, F6: -140~-5mm, F7: 0mm;

[0024] Step 5: Perform laminar flow cooling on the finished steel strip. The cooling flow rate ratio between the lower and upper manifolds is 1.2 to 1.4. The laminar flow cooling model adopts sparse cooling. After the steel strip is cooled to 600 to 700°C, it is coiled.

[0025] Furthermore, in step three, the thickness of the intermediate billet after rough rolling is controlled to be 30-35 mm.

[0026] Furthermore, an insulation cover and a hot coil box are installed on the transfer roller conveyor between steps three and four, and the intermediate billet enters the finishing mill after passing through the insulation cover and the hot coil box in sequence.

[0027] The beneficial effects of this invention are as follows: The use of slabs of appropriate length helps reduce the temperature difference between intermediate slabs and the head and tail of the coil. The use of hot-feeding and hot-charging for heating increases the core temperature of the slab, facilitating stable rolling. Four passes of roughing further reduce the temperature drop at the finishing mill inlet. During finishing, by rationally controlling rolling speed, plate crown, looper amount, bending roll force, and roll shifting, the resulting 1.2mm thick hot-rolled patterned steel plate possesses advantages such as good rolling stability, good pattern morphology, and excellent overall performance. It avoids defects such as strip tail damage, waviness, scrap, and missing patterns that occur in existing technologies during steel plate preparation. This improves the yield of ultra-thin hot-rolled patterned steel plates, reaching over 95%. Detailed Implementation

[0028] The present invention will be further described below with reference to embodiments.

[0029] The present invention discloses a rolling method for a 1.2mm ultra-thin hot-rolled patterned steel plate, wherein the steel billet used for rolling is ordinary carbon steel, and the rolling process includes the following steps:

[0030] Step 1: Control the thickness of the steel billet to be 200-250mm and the length of the billet to be 8.5m-9.5m;

[0031] Step 2: The steel billet is loaded into the slab heating furnace using a hot charging method, and the slab exit temperature is 1220~1280℃.

[0032] Step 3: Rough rolling of the steel billet is carried out using two sets of rolling mills. The first set of rolling mills performs one pass, and the second set of rolling mills performs three passes. The inlet temperature of the rough rolling mill is 1160-1200℃, the outlet temperature of the rough rolling mill is 1120-1160℃, and the outlet speed of the rough rolling mill is 2-5m / s.

[0033] Step 4: Perform finish rolling on the intermediate billet obtained in Step 3. The finish rolling inlet temperature is 1060–1120℃, the finish rolling outlet temperature is 860–900℃, and the finish rolling outlet speed is 9.5–11.0 m / s. Control the thickness of the finished steel plate to 1.2 mm. During the finish rolling process, the number of cooling water groups between stands should not exceed 1, and the number of lubrication rolling groups should not be less than 3. The finish rolling mill includes 7 sets of finish rolling rolls, namely F1 to F7, where F7 is a pattern roll, ensuring that the pattern height is ≥0.12 mm, and 6 sets of looper rolls, namely L1 to L6. The finish rolling rolls and looper rolls are controlled according to the following requirements:

[0034] Crown of finishing rolls: F1: 10~25μm, F2: 5~10μm, F3: 3~9μm, F4: 2~6μm, F5: 1~4μm, F6: 1~3μm, F7: 1~3μm;

[0035] Finishing roll gap: F1: 15~20mm, F2: 5~15mm, F3: 2~8mm, F4: 2~5mm, F5~F7: 1~3mm;

[0036] Finishing roll speeds: F1: 0.8~1.0m / s, F2: 1.5~2.0m / s, F3: 2.0~3.5m / s, F4: 3.5~5.5m / s, F5: 5.5~8.0m / s, F6: 8.0~9.8m / s, F7: 9.0~10.5m / s;

[0037] Looping roller tension: L1: 600~750N / mm 2 L2: 750~850N / mm 2 L3: 850~950N / mm 2 L4: 1000~1300N / mm 2 L5: 1300~1600N / mm 2 L6: 1700~2000N / mm 2 ;

[0038] Bending force of finishing rolls: F1~F2: 80~200N / mm 2F3~F4: 140~200N / mm 2 F5~F6: 100~120N / mm 2 F7: 40~80N / mm 2 ;

[0039] Finishing roll shifting amount: F1: 50~150mm, F2: -80~80mm, F3: -50~-50mm, F4: -40~40mm, F5: -150~30mm, F6: -140~-5mm, F7: 0mm;

[0040] Step 5: Perform laminar flow cooling on the finished steel strip. The cooling flow rate ratio between the lower and upper manifolds is 1.2 to 1.4. The laminar flow cooling model adopts sparse cooling. After the steel strip is cooled to 600 to 700°C, it is coiled.

[0041] In step three, in order to improve the efficiency of finishing rolling and the quality of steel strip forming, the thickness of the intermediate billet after rough rolling is preferably controlled within 30 to 35 mm.

[0042] To prevent the intermediate billet from cooling too quickly during the transition from the roughing mill to the finishing mill, thus lowering the finishing mill inlet temperature, a heat insulation cover and a hot coil box can be installed on the transfer roller conveyor between steps three and four. The intermediate billet passes through the heat insulation cover and the hot coil box sequentially before entering the finishing mill. The heat insulation cover and the hot coil box can ensure a uniform and stable temperature for the intermediate billet, while also helping to reduce burn-off and the formation of secondary iron oxide scale, thereby improving the surface quality of the steel.

[0043] The reasons for the limitations of the production process are explained below in conjunction with the requirements for the forming control of patterned steel plates described in this invention.

[0044] Firstly, regarding the heating regime. Since the slab heating furnace uses nozzle heating, the main heat transfer method is thermal radiation. Heat is transferred from the slab surface to the core. Therefore, when the slab is cold-charged, the core temperature is low, and the heating rate is slow. An improper heating regime can easily lead to a low core temperature, resulting in insufficient deformation transfer to the core during subsequent rough rolling. This not only increases the rolling load and rolling difficulty but also easily leads to coarse core microstructure. In contrast, when hot-feeding and hot-charging are used, the slab is directly kept warm at a high temperature and transported to the heating furnace for heating. Because the slab cools naturally in the air after continuous casting, the core temperature is higher than the surface temperature. After slab heating, the core temperature is higher, making it easier to achieve stable rolling. Therefore, this invention requires that the slab obtained after continuous casting be hot-feeded and hot-charged into the slab heating furnace, while the furnace outlet temperature is controlled at a relatively high level of 1220–1280℃.

[0045] Secondly, regarding the roughing process. Conventional roughing uses a "3+3" mode, meaning R1 and R2 are rolled in three passes each. This invention uses a "1+3" mode, reducing two rolling passes, thus minimizing temperature drop. The design of the temperature and deformation regime considers rolling in the austenite recrystallization zone. Recrystallization refines the austenite structure, improving the material's strength and plasticity. Therefore, the roughing temperature is controlled at a relatively high level, and the rolling deformation is controlled at a relatively large level, meaning the intermediate slab thickness is controlled at a relatively low level. Secondly, considering the shape control in roughing, a higher roughing temperature is used to reduce the rolling load. Therefore, this invention requires: a "1+3" roughing process with an inlet temperature of 1160–1200℃, an outlet temperature of 1120–1160℃, an outlet speed of 2–5 m / s, and an intermediate slab thickness of 30–35 mm after roughing.

[0046] Third, heat insulation covers and hot coil boxes are installed on the roller table between the roughing mill and the finishing mill. On the one hand, this is to increase the finishing rolling temperature and reduce the rolling load. On the other hand, it is to remove the surface iron oxide scale by coiling the high-temperature intermediate billet, so that the temperature of the steel plate is uniform at both ends, and the stable rolling of thin-gauge steel plates can be achieved.

[0047] Fourth, regarding the finishing rolling process. Firstly, the main function of finishing rolling is to provide a large number of nucleation sites for subsequent phase transformations through high compression ratio rolling, promoting the formation of a fine and uniform microstructure, and improving the material's strength and toughness through fine grain strengthening. This invention employs a relatively high finishing rolling temperature, specifically an inlet temperature of 1060–1120℃ and an outlet temperature of 860–900℃. This is primarily to ensure that the early stage of finishing rolling (F1–F4) remains within the austenite recrystallization region, forming a uniform and fine equiaxed grain structure through recrystallization. The later stage of finishing rolling (F5–F7) is within the austenite non-recrystallization region, providing sufficient nucleation work and a large number of nucleation sites for subsequent phase transformations through the flattening of the austenite microstructure. Additionally, this invention employs a relatively high finishing rolling exit speed of 9.5–11.0 m / s, mainly to enable the steel plate to complete finishing rolling quickly, reducing the temperature difference between the beginning and end of the plate caused by natural temperature drop, thereby mitigating the performance differences between the beginning and end of the steel plate.

[0048] Secondly, the finishing rolling process also considers the issue of shape control for thin-gauge steel plates. The steel plates described in this invention are relatively thin, with a large finishing rolling compression ratio, making shape control difficult. Therefore, this invention requires: First, that the number of cooling water groups opened between stands not exceed one group to reduce the temperature drop during the finishing rolling process; Second, that the number of lubrication rolling groups open not less than three groups, using oil-water lubrication to reduce friction on the steel plate surface and reduce the finishing rolling load; Third, that the finishing rolling process rationally controls rolling speed, plate crown, looper amount, bending roll force, and roll shifting amount, appropriately increasing the rolling force of F7 and reducing the roll shifting amount of F7, which is beneficial for controlling the pattern height and plate shape, resulting in hot-rolled steel strips with good rolling stability and excellent overall performance.

[0049] Setting the crown of the finishing rolls to a reasonable value is beneficial to improving the strip shape accuracy throughout the process and avoiding defects such as waviness in the strip. Taking into account the thickness of the intermediate billet and finished product of thin strip and the temperature drop during the rolling process, the finishing roll gap design can achieve a reasonable rolling load distribution while ensuring the amount of finishing deformation. Too high a looper roll tension can easily cause the strip to be stretched too narrow, while too low a looper roll tension can easily cause insufficient stretching of extremely thin strip between the two stands, resulting in poor stability of the strip between the stands and changes in strip shape. In addition, there is also a risk of strip breakage due to looper lifting. The setting of the finishing roll bending force and roll shifting amount is mainly to adapt to the crown of the intermediate billet after roughing, while realizing the control of strip crown, straightness, and shape, and avoiding defects such as waviness in the strip.

[0050] The exit speed of the finishing mill is mainly affected by the temperature drop of the strip during the finishing rolling process. A certain rolling speed is required to ensure that the temperature drop of the strip during the finishing rolling process can meet the requirements of the entry and exit temperatures. The thinner the strip, the greater the temperature drop. In addition, for materials such as automotive structural steel and high-strength weathering steel, the addition of alloying elements such as Ti, Cr, and Cu leads to an increased rate of temperature drop in the strip, thus requiring further increases in rolling speed.

[0051] Fifth, regarding laminar flow cooling: First, to avoid the formation of coarse ferrite or cementite structures, a relatively high laminar flow cooling rate of 10–30°C / s is required to refine the grains and improve the strength and plasticity of the material. Second, the coiling temperature is controlled at 600–700°C; appropriately increasing the coiling temperature is beneficial for improving the elongation of thin-gauge steel plates. Third, due to the influence of gravity, the cooling water in the lower manifold sprays upwards to the surface of the steel plate at a relatively low rate. Therefore, to ensure that the cooling rates of the upper and lower surfaces are similar, the flow rate of the cooling water in the lower manifold should be appropriately higher than that in the upper manifold. Based on industrial production experience, this invention controls the flow rate ratio of the lower and upper manifolds at 1.2–1.4. Fourth, since the steel plate undergoes a phase transformation during laminar flow cooling, internal stress is easily generated during the phase transformation, and the internal stress increases with a higher cooling rate. Therefore, this invention appropriately reduces the cooling rate of the steel plate while meeting the performance requirements of the steel plate, i.e., adopting a sparse cooling water mode, closing one manifold after every two manifolds are opened.

[0052] The specific embodiments of the present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the embodiments described herein.

[0053] Example 1

[0054] Conventional carbon structural steel billets, 8.5m in length, are used. A 1.2mm thick steel plate is produced through a process of heating, rough rolling, hot coiling, finish rolling, laminar flow cooling, and coiling. The specific process is as follows: The billet is hot-charged into the slab heating furnace, with an exit temperature of 1269℃. The roughing mill inlet temperature is 1195℃, the roughing mill outlet temperature is 1155℃, and the roughing mill outlet speed is 3.3m / s, resulting in an intermediate slab thickness of 30mm. After rough rolling, the intermediate slab is conveyed via roller conveyor, insulated under a heat shield, coiled in the hot coiling box, and then sent to the finish rolling mill. The finish rolling inlet temperature is 1089℃, the finish rolling outlet temperature is 878℃, and the finish rolling outlet speed is 9.6m / s. One set of inter-stand cooling water is activated, and three sets of lubrication rolling water are activated. The finished steel plate is subjected to laminar flow cooling. The laminar flow cooling model consists of two sets of pipes and one set of pipes. The water flow ratio between the lower and upper manifolds is 1.32, and the coiling temperature is 700℃.

[0055] The patterned plate described in Example 1 has a thickness of 1.2 mm, a good plate shape, and a pattern height of 0.12 mm.

[0056] Example 2

[0057] Conventional carbon structural steel billets, with a slab length of 9.5m, are used. A 1.2mm thick steel plate is produced through a process of heating, rough rolling, hot coiling, finish rolling, laminar flow cooling, and coiling. The specific process is as follows: The billet is hot-charged into the slab heating furnace, with an exit temperature of 1275℃. The rough rolling mill inlet temperature is 1195℃, the rough rolling mill outlet temperature is 1168℃, the rough rolling mill outlet speed is 4.0m / s, and the intermediate slab thickness obtained after rough rolling is 35mm. After rough rolling, the intermediate slab is conveyed via roller conveyor, successively insulated by a heat preservation cover, coiled in the hot coiling box, and then sent to the finish rolling mill. The finishing mill inlet temperature is 1100℃, the finishing mill outlet temperature is 895℃, the finishing mill outlet speed is 10.5m / s, the interstand cooling water is not turned on, the lubrication rolling is turned on in 5 groups, the steel plate after finishing milling is cooled by laminar flow, the laminar flow cooling model is 2 groups of pipes and 1 group of pipes are turned on, the water flow ratio of the lower manifold and the upper manifold is 1.27, and the coiling temperature is 605℃.

[0058] The patterned plate described in Example 2 has a thickness of 1.2 mm, a good plate shape, and a pattern height of 0.13 mm.

[0059] Example 3

[0060] Conventional carbon structural steel billets, with a slab length of 9.0m, are used. A 1.2mm thick steel plate is produced through a process of heating, rough rolling, hot coiling, finish rolling, laminar flow cooling, and coiling. The specific process is as follows: The billet is hot-charged into the slab heating furnace, with an exit temperature of 1263℃. The roughing mill inlet temperature is 1195℃, the roughing mill outlet temperature is 1167℃, the roughing mill outlet speed is 3.2m / s, and the intermediate slab thickness obtained after rough rolling is 33mm. After rough rolling, the intermediate slab is conveyed via roller conveyor, insulated under a heat-insulating cover, coiled in the hot coiling box, and then sent to the finish rolling mill. The finishing mill inlet temperature is 1105℃, the finishing mill outlet temperature is 894℃, the finishing mill outlet speed is 9.9m / s, the interstand cooling water is not turned on, the lubrication rolling is turned on in 5 groups, the finished steel plate is subjected to laminar flow cooling, the laminar flow cooling rate is 30℃ / s, the laminar flow cooling model is 2 groups of pipes and 1 group of pipes are turned on, the water flow ratio of the lower manifold and the upper manifold is 1.32, and the coiling temperature is 655℃.

[0061] The patterned plate described in Example 3 has a thickness of 1.2 mm, a good plate shape, and a pattern height of 0.12 mm.

[0062] Comparative Example 1

[0063] Conventional carbon structural steel billets with a slab length of 11.0m were used. A 1.2mm thick steel plate was produced through a process of heating, rough rolling, hot coiling, finish rolling, laminar flow cooling, and coiling. The specific process is as follows: The billet was cold-charged into the slab heating furnace, with an exit temperature of 1223℃. The rough rolling inlet temperature was 1167℃, the rough rolling outlet temperature was 1138℃, and the rough rolling outlet speed was 3.0m / s, resulting in an intermediate slab thickness of 33mm. After rough rolling, the intermediate slab was conveyed via roller conveyor to the finish rolling mill. The finish rolling employed conventional rolling technology, with an inlet temperature of 1071℃, a finish rolling outlet temperature of 860℃, and a finish rolling outlet speed of 9.0m / s. Cooling water between stands was not activated; lubrication rolling was activated in 5 groups. The finished steel plate underwent laminar flow cooling, and the coiling temperature was 660℃.

[0064] The patterned plate described in Comparative Example 1 has a thickness of 1.2 mm, a poor plate shape, and a pattern height of 0.10 mm.

[0065] Therefore, by adopting the production process of this invention, the problems of rolling ultra-thin patterned steel plates and material forming performance can be solved using ordinary carbon steel and conventional hot rolling mills, providing a new approach for the preparation of ultra-thin patterned plates, and possessing good operability and scalability.

Claims

1. A rolling method of a 1.2 mm ultra-thin gauge hot-rolled patterned steel plate, characterized in that: the steel casting blank for rolling is a common carbon steel, and the rolling process comprises the following steps: Step one, the thickness of the steel casting blank is controlled to be 200-250 mm, and the length of the casting blank is 8.5-9.5 m; Step two, the steel casting blank is loaded into the slab heating furnace in a hot charging mode, and the slab discharge temperature is 1220-1280℃; Step three, the steel casting blank is coarsely rolled, two groups of rolling mills are adopted, the first group of rolling mills is rolled in one pass, and the second group of rolling mills is rolled in three passes, the inlet temperature of coarse rolling is 1160-1200℃, the outlet temperature of coarse rolling is 1120-1160℃, the outlet speed of coarse rolling is 2-5 m / s, and the thickness of the intermediate blank after coarse rolling is controlled to be 30-35 mm; Step four, the intermediate blank obtained in step three is finely rolled, a heat preservation cover and a hot coil box are arranged on the transmission roller way between step three and step four, the intermediate blank passes through the heat preservation cover and the hot coil box in sequence and then enters the finishing rolling mill group, the inlet temperature of finishing rolling is 1060-1120℃, the outlet temperature of finishing rolling is 860-900℃, the outlet speed of finishing rolling is 9.5-11.0 m / s, and the thickness of the steel plate after finishing rolling is controlled to be 1.2 mm; the number of groups of cooling water opened during the finishing rolling process is not more than 1 group, and the number of groups of lubricating rolling opened is not less than 3 groups; the finishing rolling mill group comprises seven finishing rolling mills F1-F7 and six live roll mills L1-L6, the finishing rolling mill F7 is a patterned roll, and the finishing rolling mill and the live roll mill are controlled according to the following requirements: the finishing rolling mill crown: F1: 10-25 μm, F2: 5-10 μm, F3: 3-9 μm, F4: 2-6 μm, F5: 1-4 μm, F6: 1-3 μm, F7: 1-3 μm; the finishing rolling mill gap: F1: 15-20 mm, F2: 5-15 mm, F3: 2-8 mm, F4: 2-5 mm, F5-F7: 1-3 mm; the finishing rolling mill speed: F1: 0.8-1.0 m / s, F2: 1.5-2.0 m / s, F3: 2.0-3.5 m / s, F4: 3.5-5.5 m / s, F5: 5.5-8.0 m / s, F6: 8.0-9.8 m / s, F7: 9.5-11.0 m / s; Loop tension: L1: 600~750 N / mm 2 , L2: 750~850 N / mm 2 , L3: 850~950 N / mm 2 , L4: 1000~1300 N / mm 2 , L5: 1300~1600 N / mm 2 , L6: 1700~2000 N / mm 2 ; F1~F2: 80~200 N / mm 2 F3~F4: 140~200 N / mm 2 F5~F6: 100~120 N / mm 2 F7: 40~80 N / mm 2 ; the finishing rolling mill roll shifting amount: F1: 50-150 mm, F2: -80-80 mm, F3: -50--50 mm, F4: -40-40 mm, F5: -150-30 mm, F6: -140--5 mm, F7: 0 mm; Step five, the steel plate after finishing rolling is subjected to laminar cooling, the cooling flow rate ratio of the lower header and the upper header is 1.2-1.4, the laminar cooling model adopts sparse cooling, and the steel strip is coiled after being cooled to 600-700℃.