Anti-buckling control method for cold rolling vertical continuous annealing production of limit wide thin plate

Abstract

The invention discloses an anti-buckling control method for a cold rolling vertical continuous annealing production limit wide thin plate, which comprises the following steps: setting the temperature of a heating area and a soaking area of a vertical continuous annealing furnace to be 790-800 DEG C, and setting the tension of the heating area and the soaking area to be 6-7N / mm < 2 >; the temperature of a slow cooling area of the vertical continuous annealing furnace is set to be 620-630 DEG C, and the cooling rate of the slow cooling area is set to be 6.2-6.7 DEG C / s; the temperature of a flash cooling area of the vertical continuous annealing furnace is set to be 320-330 DEG C, and the cooling rate of the flash cooling area is set to be 37.5-40.6 DEG C / s; the temperature of an overaging area of the vertical continuous annealing furnace is set to be 300-310 DEG C, and the tension of the overaging area is set to be 7-8 N / mm < 2 >. According to the anti-buckling control method for cold rolling vertical continuous annealing production of the limit wide thin plate, buckling is effectively prevented by selecting the appropriate annealing temperature and the appropriate tension in the annealing furnace through the steel belt in the annealing furnace, especially the appropriate cooling rate of conversion from the heating area to the cooling area.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology. Specifically, this invention relates to a method for preventing warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates. Background Technology

[0002] The cold-rolled vertical continuous annealing line mainly produces cold-rolled sheets with diameters of 0.4-2.5mm and 900-2000mm, including automotive sheets, appliance sheets, and ordinary structural sheets.

[0003] Due to its high efficiency and continuous production, the annealing temperature is relatively high, and the continuous production process is relatively long (including heating zone, soaking zone, slow cooling zone, flash cooling zone, over-aging zone and final cooling zone). There is not much production risk when producing conventional products. However, when producing wide and thin products, especially the extremely wide and thin ones, there is a risk of warping. This not only affects product quality, but if the warping is too severe to be removed from the furnace, the furnace must be opened, which poses a greater production risk.

[0004] There are three main types of risk points for strip curling: one is that the temperature of the strip in the heating zone is not suitable for the temperature of the furnace rolls, and the excessive thermal expansion and contraction of the roll surface causes hot strip curling; another is that when the heating zone turns into the cooling zone, the unsuitable cooling rate causes the temperature of the strip in a local area to deviate too much from that of the furnace roll surface, resulting in cold curling; and the third is that the temperature of the strip in the cooling zone is not suitable for the tension in the furnace, which causes the strip to deform too much, resulting in secondary cold curling.

[0005] Chinese patent CN103014500A discloses an ultra-wide SEDDQ grade deep-drawing automotive sheet and its production method. The main method is to control the composition, annealing temperature, leveling process and production plan to ensure that the ultra-wide SEDDQ grade deep-drawing automotive sheet achieves excellent mechanical properties while realizing the stable flow of the strip in the furnace.

[0006] Chinese patent CN103255277A discloses a method for producing wide and thin IF steel through continuous annealing, which mainly involves speed, temperature and tension schemes, including the cooling rate of the final cooling section and the speed control of the variable frequency fan.

[0007] Chinese patent CN113528955A discloses a high-performance wide-width IF steel and its production method, which includes composition design, hot rolling process, and speed, tension, and temperature in cold rolling annealing process.

[0008] This invention provides a method for controlling the warping of ultra-wide and thin steel strips produced by cold rolling vertical continuous annealing. Specifically, it addresses how to effectively prevent cold warping of the steel strip by selecting appropriate annealing temperature, furnace tension, and cooling rate during the transition from heating to cooling zones in the annealing furnace, thereby ultimately achieving product quality control. Summary of the Invention

[0009] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a method for preventing warping in the production of extremely wide and thin plates using cold-rolled vertical continuous annealing. The purpose is to prevent cold warping of the steel strip by effectively controlling the annealing temperature of the steel strip in the annealing furnace, the tension in the annealing furnace, and the cooling rate during the transition from the heating zone to the cooling zone, thereby ultimately achieving product quality control.

[0010] To achieve the above objectives, the technical solution adopted by this invention is: a method for controlling warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates, comprising:

[0011] The temperature of the heating zone and the soaking zone of the vertical continuous annealing furnace are set at 790℃-800℃, and the tension of the heating zone and the soaking zone is set at 6-7 N / mm. 2 ;

[0012] The temperature of the slow cooling zone of the vertical continuous annealing furnace is set at 620℃-630℃, and the cooling rate of the slow cooling zone is set at 6.2℃ / s-6.7℃ / s;

[0013] The temperature of the flash cooling zone in the vertical continuous annealing furnace is set at 320℃-330℃, and the cooling rate of the flash cooling zone is set at 37.5℃ / s-40.6℃ / s.

[0014] The temperature of the over-aging zone in the vertical continuous annealing furnace is set at 300℃-310℃, and the tension in the over-aging zone is set at 7-8 N / mm. 2 ;

[0015] The hot rolling material is arranged to pass through the heating zone, the homogenizing zone, the slow cooling zone, the flash cooling zone, the over-aging zone, and the final cooling zone of the vertical continuous annealing furnace in sequence.

[0016] The ironing roller material is provided in 4-6 rolls, with a width of 1800mm-2000mm and a thickness of 0.7mm-0.9mm.

[0017] The hot-pressing rollers are progressively fed into a vertical continuous annealing furnace to gradually preheat the furnace rollers. The width difference between two adjacent hot-pressing rollers is 40mm-50mm.

[0018] The temperature of the final cooling zone in the vertical continuous annealing furnace is set at 150℃-160℃, and the tension in the final cooling zone is set at 6.5-7.5 N / mm. 2 .

[0019] When the heating roller material is DC01, the temperature of the heating zone and the homogenizing zone of the vertical continuous annealing furnace is set to 790℃, and the tension of the heating zone and the homogenizing zone is set to 6.5-7 N / mm. 2 .

[0020] When the heating roller material is SPCC, the temperature of the heating zone and the homogenizing zone of the vertical continuous annealing furnace is set to 800℃, and the tension of the heating zone and the homogenizing zone is set to 6-6.5 N / mm. 2 .

[0021] When the heat-pressing roller material is DC01, the temperature of the slow cooling zone is set to 620℃, the temperature of the flash cooling zone is set to 320℃, the temperature of the over-aging zone is set to 300℃, and the temperature of the final cooling zone is set to 150℃.

[0022] When the heat-pressing roller material is SPCC, the temperature of the slow cooling zone is set to 630℃, the temperature of the flash cooling zone is set to 330℃, the temperature of the over-aging zone is set to 310℃, and the temperature of the final cooling zone is set to 160℃.

[0023] When the heating roller material is DC01, the cooling rate of the slow cooling zone is set to 6.7℃ / s, and the cooling rate of the flash cooling zone is set to 40.6℃ / s.

[0024] When the heat-pressing roller material is SPCC, the cooling rate of the slow cooling zone is set to 6.2℃ / s, and the cooling rate of the flash cooling zone is set to 37.5℃ / s.

[0025] The present invention provides a method for preventing warping in cold-rolled vertical continuous annealing production of ultra-wide and thin plates. By selecting appropriate annealing temperature, furnace tension, and especially appropriate cooling rate from heating zone to cooling zone, warping can be effectively prevented. Attached Figure Description

[0026] This manual includes the following figures, which illustrate the following:

[0027] Figure 1 This is a schematic diagram of the layout of each area of ​​a cold-rolling vertical continuous annealing furnace;

[0028] Figure 2 This is a schematic diagram of a board surface without any curves.

[0029] The diagram is marked as follows:

[0030] 1. Heating zone; 2. Soaking zone; 3. Slow cooling zone; 4. Flash cooling zone; 5. Over-aging zone; 6. Final cooling zone; 7. Extremely wide and thin strip steel; 8. Furnace rollers. Detailed Implementation

[0031] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention, and to facilitate its implementation.

[0032] like Figure 1 As shown in the figure, this invention provides a method for controlling warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates, including:

[0033] The temperature of the heating zone and the soaking zone of the vertical continuous annealing furnace are set at 790℃-800℃, and the tension of the heating zone and the soaking zone is set at 6-7 N / mm. 2 ;

[0034] The temperature of the slow cooling zone of the vertical continuous annealing furnace is set at 620℃-630℃, and the cooling rate of the slow cooling zone is set at 6.2℃ / s-6.7℃ / s;

[0035] The temperature of the flash cooling zone in the vertical continuous annealing furnace is set at 320℃-330℃, and the cooling rate of the flash cooling zone is set at 37.5℃ / s-40.6℃ / s.

[0036] The temperature of the over-aging zone in the vertical continuous annealing furnace is set at 300℃-310℃, and the tension in the over-aging zone is set at 7-8 N / mm. 2 ;

[0037] The temperature of the final cooling zone in the vertical continuous annealing furnace is set at 150℃-160℃, and the tension in the final cooling zone is set at 6.5-7.5 N / mm. 2 ;

[0038] The hot rolling material is arranged to pass through the heating zone, the homogenizing zone, the slow cooling zone, the flash cooling zone, the over-aging zone, and the final cooling zone of the vertical continuous annealing furnace in sequence.

[0039] Specifically, the technical problem to be solved by the present invention is to provide a method to improve the prevention of warping in continuous annealing production of extremely wide and thin plates, which addresses the shortcomings of the existing technology. The improvement lies in the control of the cooling rate of the steel strip as it transitions from the heating zone to the cooling zone, which can effectively avoid cold warping caused by improper control of the cooling rate.

[0040] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0041] One type of thermal warping is caused by the mismatch between the strip temperature in the heating zone and the furnace roll temperature. This can be addressed by selecting an appropriate amount of low-cost SPCC or DC01 steel in advance to gradually approach the limit width of the hot roll material, while appropriately reducing the heating zone temperature to ensure uniform temperature across the entire width of the furnace roll. This prevents the steel strip from warping due to excessive temperature differences at the edges and middle of the furnace roll, and excessive thermal expansion and contraction of the roll surface.

[0042] In the case of steel strips in the heating zone turning into the slow cooling zone or flash cooling zone, an inappropriate cooling rate can cause cold warping. This can be prevented by selecting an appropriate speed, appropriately reducing the temperature of the cooling zone, and controlling the tension inside the furnace. This can avoid excessive temperature deviation between the local area of ​​the steel strip and the surface of the furnace rolls due to excessively fast cooling.

[0043] Secondary cooling warping can be caused by an unsuitable temperature of the strip in the cooling zone and the corresponding tension in the furnace. This can be addressed by appropriately reducing the temperature of the slow cooling zone, flash cooling zone, over-aging zone, and final cooling zone, as well as appropriately reducing the tension in the furnace in the slow cooling zone, flash cooling zone, and final cooling zone. This releases residual stress in the strip and prevents excessive tension in the furnace from causing excessive deformation of the strip, which in turn leads to secondary cooling warping.

[0044] In this embodiment of the invention, the main influencing factors and their mechanisms of action are tracked on-site based on experimental data. A method for preventing the warping of extremely wide and thin plates in a cold-rolled vertical annealing furnace is provided. By selecting appropriate annealing temperature, furnace tension, and especially appropriate cooling rate from heating zone to cooling zone, cold warping can be effectively prevented, ultimately achieving product quality control and stable production line operation.

[0045] In this embodiment of the invention, 4-6 rolls of heating rollers are provided, with a width of 1800mm-2000mm and a thickness of 0.7mm-0.9mm. If the heating rollers are too thin (<0.7mm), the heat capacity will be insufficient; if the heating rollers are too thick (>0.9mm), the residence time in the furnace will increase, affecting efficiency.

[0046] In this embodiment of the invention, the hot-rolled steel rolls are progressively fed into a vertical continuous annealing furnace, gradually preheating the furnace rolls. The width difference between two adjacent rolls is 40mm-50mm, meaning the width of the roll entering the annealing furnace is 40mm-50mm smaller than the width of the roll entering the furnace afterward. By using low-carbon steel hot-rolled steel rolls (SPCC / DC01) with progressively increasing width, the temperature difference in the width direction (edge ​​and center) of the furnace rolls is reduced before the formal production of ultra-wide thin plates, preventing uneven thermal expansion that could cause the steel strip to warp.

[0047] In this embodiment of the invention, SPCC or DC01 steel (low carbon steel with a stable coefficient of thermal expansion) is used as a transition material to gradually approach the limit width, and the temperature distribution of the furnace roller is "smoothed" through its uniform heat absorption characteristics.

[0048] In this embodiment of the invention, 4-6 rolls of SPCC or DC01 (width specifications of 1800mm-2000mm, width difference of 40mm-50mm per roll, thickness specifications of 0.7mm-0.9mm) of hot-pressing rollers are selected in advance and progressively fed into a vertical continuous annealing furnace for production. This ensures that the edges and middle of the furnace rollers are heated evenly, effectively avoiding the risk of warping of the extreme width plates when they are put into the furnace.

[0049] To prevent thermal warping and the risk of strip deviation caused by excessively high strip temperature in the heating zone, the strip temperature in the heating zone can be appropriately reduced (790℃-800℃). At the same time, the tension in the furnace in the heating zone should be appropriately increased (6-7 N / mm2) to prevent the risk of speed fluctuation caused by strip deviation in the furnace.

[0050] like Figure 1 As shown, the cooling zone transitions to the slow cooling zone and the flash cooling zone. The cooling rate is crucial; an excessively fast cooling rate can easily cause cooling warping. The production line speed should be properly controlled (120mpm-130mpm) to ensure that the cooling rate is appropriately controlled. The cooling rate of the slow cooling zone is set to 6.2℃ / s-6.7℃ / s, and the cooling rate of the flash cooling zone is set to 37.5℃ / s-40.6℃ / s.

[0051] To prevent the risk of cold warping during cooling, the temperatures in the slow cooling zone (620℃-630℃) and flash cooling zone (320℃-330℃) should be appropriately reduced. Simultaneously, the furnace tension in the slow cooling zone should be reduced to 6.5-7.5 N / mm. 2 ), furnace tension in the flash cooling zone (7-8 N / mm) 2 )control.

[0052] like Figure 1 As shown, the over-aging region is relatively long. It is advisable to appropriately reduce the temperature in this region (300℃-310℃) and control the furnace tension (7-8 N / mm). 2 To prevent secondary cooling and warping.

[0053] like Figure 1 As shown, in the final cooling zone, the temperature in this zone should be appropriately reduced (150℃-160℃) and the furnace tension controlled (6.5-7.5 N / mm). 2 To prevent secondary cooling and warping.

[0054] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows:

[0055] This invention combines on-site tracking experiments to investigate and summarize the main influencing factors and mechanisms of action, especially exploring a suitable cooling rate during the transition from the heating zone to the cooling zone in the risk of scour.

[0056] The above method can effectively ensure the stable production of cold-rolled ultra-wide and thin products. Currently, the price of ultra-wide and thin products is about 300 yuan / ton higher than that of regular products. Based on an estimated monthly order of 1,000 tons of such products, it is expected to increase the added value by 240,000 yuan / month.

[0057] Example 1

[0058] In this embodiment, the heating roller material is DC01, and four rolls of heating roller material are provided.

[0059] In this embodiment, the tension in the heating zone and the heat spreader is set to 6.5-7 N / mm. 2 The tension in the slow cooling zone is set to 7-7.5 N / mm. 2 The tension in the flash cooling zone is set to 7.5-8 N / mm. 2 The tension in the over-aged region is set to 7.5-8 N / mm. 2 The tension in the final cooling zone is set to 7-7.5 N / mm. 2 .

[0060] In this embodiment, the temperature of the heating zone and the homogenization zone of the vertical continuous annealing furnace is set to 790°C, the temperature of the slow cooling zone is set to 620°C, the temperature of the flash cooling zone is set to 320°C, the temperature of the over-aging zone is set to 300°C, and the temperature of the final cooling zone is set to 150°C.

[0061] In this embodiment, the cooling rate of the slow cooling zone is set to 6.7℃ / s, and the cooling rate of the flash cooling zone is set to 40.6℃ / s.

[0062] Example 2

[0063] In this embodiment, the ironing roller material is SPCC, and there are 6 rolls of ironing roller material.

[0064] In this embodiment, the tension in the heating zone and the heat spreader is set to 6-6.5 N / mm. 2 The tension in the slow cooling zone is set to 6.5-7 N / mm. 2 The tension in the flash cooling zone is set to 7-7.5 N / mm. 2 The tension in the over-aged region is set to 7-7.5 N / mm. 2 The tension in the final cooling zone is set to 6.5-7 N / mm. 2 .

[0065] In this embodiment, the temperature of the heating zone and the homogenization zone of the vertical continuous annealing furnace is set to 800°C, the temperature of the slow cooling zone is set to 630°C, the temperature of the flash cooling zone is set to 330°C, the temperature of the over-aging zone is set to 310°C, and the temperature of the final cooling zone is set to 160°C.

[0066] In this embodiment, the cooling rate of the slow cooling zone is set to 6.2℃ / s, and the cooling rate of the flash cooling zone is set to 37.5℃ / s.

[0067] Table 1. Reference examples of process parameters for embodiments of the present invention (DC06, 0.9mm*2000mm)

[0068] Control zone Example 1 Example 2 Roller material DC01 / 4 rolls SPCC / 6 rolls Temperature / tension in heating zone 790℃ / (6.5-7)N / mm2 800℃ / (6-6.5)N / mm2 Temperature / tension in soaking zone 790℃ / (6.5-7)N / mm2 800℃ / (6-6.5)N / mm2 Strip running speed 130mpm 120mpm Temperature / tension in slow cooling zone 620℃ / (7-7.5)N / mm2 630℃ / (6.5-7)N / mm2 Cooling rate in slow cooling zone 6.7℃ / s 6.2℃ / s Temperature / tension in flash cooling zone 320℃ / (7.5-8)N / mm2 330℃ / (7-7.5)N / mm2 Cooling rate in flash cooling zone 40.6℃ / s 37.5℃ / s Temperature / tension in overaging zone 300℃ / (7.5-8)N / mm2 310℃ / (7-7.5)N / mm2 Temperature / tension in final cooling zone 150℃ / (7-7.5)N / mm2 160℃ / (6.5-7)N / mm2 Bulging control effect No bulging on plate surface No bulging on plate surface

[0069] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A method for controlling warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates, characterized in that, include: The temperature of the heating zone and the soaking zone of the vertical continuous annealing furnace are set at 790℃-800℃, and the tension of the heating zone and the soaking zone is set at 6-7 N / mm. 2 ; The temperature of the slow cooling zone of the vertical continuous annealing furnace is set at 620℃-630℃, and the cooling rate of the slow cooling zone is set at 6.2℃ / s-6.7℃ / s; The temperature of the flash cooling zone in the vertical continuous annealing furnace is set at 320℃-330℃, and the cooling rate of the flash cooling zone is set at 37.5℃ / s-40.6℃ / s. The temperature of the over-aging zone in the vertical continuous annealing furnace is set at 300℃-310℃, and the tension in the over-aging zone is set at 7-8 N / mm. 2 ; The hot rolling material is arranged to pass through the heating zone, the homogenizing zone, the slow cooling zone, the flash cooling zone, the over-aging zone, and the final cooling zone of the vertical continuous annealing furnace in sequence.

2. The method for preventing warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates according to claim 1, characterized in that, The ironing roller material is provided in 4-6 rolls, with a width of 1800mm-2000mm and a thickness of 0.7mm-0.9mm.

3. The method for preventing warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates according to claim 2, characterized in that, The hot-pressing rollers are progressively fed into a vertical continuous annealing furnace to gradually preheat the furnace rollers. The width difference between two adjacent hot-pressing rollers is 40mm-50mm.

4. The method for preventing warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates according to any one of claims 1 to 3, characterized in that, The temperature of the final cooling zone in the vertical continuous annealing furnace is set at 150℃-160℃, and the tension in the final cooling zone is set at 6.5-7.5 N / mm. 2 .

5. The method for preventing warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates according to any one of claims 1 to 3, characterized in that, When the heating roller material is DC01, the temperature of the heating zone and the homogenizing zone of the vertical continuous annealing furnace is set to 790℃, and the tension of the heating zone and the homogenizing zone is set to 6.5-7 N / mm. 2 .

6. The method for preventing warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates according to any one of claims 1 to 3, characterized in that, When the heating roller material is SPCC, the temperature of the heating zone and the homogenizing zone of the vertical continuous annealing furnace is set to 800℃, and the tension of the heating zone and the homogenizing zone is set to 6-6.5 N / mm. 2 .

7. The method for preventing warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates according to any one of claims 1 to 3, characterized in that, When the heat-pressing roller material is DC01, the temperature of the slow cooling zone is set to 620℃, the temperature of the flash cooling zone is set to 320℃, the temperature of the over-aging zone is set to 300℃, and the temperature of the final cooling zone is set to 150℃.

8. The method for preventing warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates according to any one of claims 1 to 3, characterized in that, When the heat-pressing roller material is SPCC, the temperature of the slow cooling zone is set to 630°C, the temperature of the flash cooling zone is set to 330°C, the temperature of the over-aging zone is set to 310°C, and the temperature of the final cooling zone is set to 160°C.

9. The method for preventing warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates according to any one of claims 1 to 3, characterized in that, When the heat-pressing roller material is DC01, the cooling rate of the slow cooling zone is set to 6.7℃ / s, and the cooling rate of the flash cooling zone is set to 40.6℃ / s.

10. The method for preventing warping in cold-rolled vertical continuous annealing production of extremely wide and thin plates according to any one of claims 1 to 3, characterized in that, When the heat-pressing roller material is SPCC, the cooling rate of the slow cooling zone is set to 6.2℃ / s, and the cooling rate of the flash cooling zone is set to 37.5℃ / s.

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