A production method of a winter controlled TMCP high-strength steel plate shape

Abstract

The application discloses a production method for controlling the shape of a high-strength steel plate in winter TMCP, which comprises the following steps: step one, setting the slab discharge temperature to be 1220-1270 DEG C, and performing rough descaling once; step two, rough rolling stage; step three, finish rolling stage; step four, pre-straightening treatment is performed on the steel plate after rolling; step five, the opening cooling temperature of the steel plate with a thickness of 10-20 mm is greater than or equal to 780 DEG C; step six, the water temperature of the rapid cooling device is controlled to be 26+ / -4 DEG C, the edge is shielded, the head and tail are shielded, the frame height of the rapid cooling device for the steel plate with a thickness of 10-20 mm is set to be 500-600 mm, and the frame height is divided into four areas A, B, C and D; and step eight, a 9-roller hot straightening machine is adopted for straightening, the straightening temperature is less than or equal to 350 DEG C, the entry roll gap of the straightening machine is the thickness of the steel plate minus 2-9 mm, and the straightening speed is 0.5-1.0 m / s. The method can effectively avoid the warping, head buckling and edge wave of the high-strength steel plate caused by the non-uniform temperature after rapid cooling, and improve the production efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of shape control of thick TMCP steel plates, specifically to a production method for controlling the shape of TMCP high-strength steel plates in winter. Background Technology

[0002] With the improvement of medium and heavy plate equipment and the advancement of rolling mill technology, TMCP technology, which combines controlled rolling and controlled cooling, has been gradually promoted and applied to low alloy steel, bridge steel, pipelines, and engineering machinery.

[0003] Currently, controlling the final cooling temperature of the finishing roll and utilizing rapid cooling devices to accelerate the cooling of the steel plate allows the steel plate properties to achieve the effect of online quenching, reducing the need for offline quenching processes. Ultimately, only TMCP + offline tempering is required to achieve the ideal performance of the final steel plate. However, in winter, the cooling rate during steel plate rolling increases, the surface temperature of the steel plate drops rapidly before entering the rapid cooling device, and the lower water temperature in winter further increases the overall cooling rate. When producing thin-gauge steel plates with a yield strength ≥460MPa, it is difficult to control the plate shape. Even after straightening in winter, steel plates still exhibit warping, edge wavy edges, and buckling. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art by providing a production method for controlling the shape of TMCP high-strength steel plates in winter.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a production method for controlling the shape of TMCP high-strength steel plates in winter, comprising the following steps:

[0006] Step 1: Set the slab exit temperature to 1220℃~1270℃ and perform one coarse descaling.

[0007] Step 2: In the roughing stage, the overall reduction in the first 4 passes reaches 35% to 55%. Descaling of the roughing mill body is carried out in the 1st to 3rd passes. The final rolling temperature of the roughing mill is ≥1050℃.

[0008] Step 3: Finishing stage, the reduction in the last 3 passes is ≥6%, and the bending roll force is controlled at 3500~4200kN. For steel plates with a thickness of 10~20mm, the initial rolling temperature is ≥910℃, and a leveling pass is added after the final rolling, with a reduction of 0~0.5mm, a rolling roll speed of 4.0~6.0m / s, and a final rolling temperature of ≥820℃.

[0009] Step 4: The rolled steel plate undergoes pre-straightening treatment;

[0010] Step 5: For steel plates with a thickness of 10-20mm, the initial cooling temperature should be ≥780℃;

[0011] Step 6: The cooling water temperature of the rapid cooling device is controlled at 26±4℃. Side shielding and head and tail shielding are set up, and it is divided into four zones: A, B, C and D.

[0012] Step 7: Final cooling temperature of the steel plate ≤ 300℃;

[0013] Step 8: Straighten the steel plate using a 9-roll hot straightener at a temperature of ≤350℃. The inlet roll gap of the straightener should be 2-9 mm less than the thickness of the steel plate. The straightening speed should be 0.5-1.0 m / s.

[0014] Based on the above technical solutions, the preferred method is as follows: in the finishing rolling stage, for steel plates with a thickness of >20-30mm, the initial rolling temperature is ≥900℃, an additional leveling pass is added before the last pass, the reduction is 1.5-3mm, the rolling roll speed is 3.0-5.0m / s, and the final rolling temperature is ≥860℃.

[0015] Based on the above technical solutions, the preferred method is that, in the finishing rolling stage, for steel plates with a thickness >30mm, the initial rolling temperature is ≥900℃, the rolling speed of the last three passes is ≥3.0m / s, and the final rolling temperature is ≥860℃.

[0016] Based on the above technical solutions, the preferred cooling temperature for steel plates with a thickness of >20-30mm is ≥810℃, and the cooling temperature for steel plates with a thickness of >30mm is ≥820℃.

[0017] Based on the above technical solutions, the preferred steel plate thickness is 10-20mm, the frame height of the rapid cooling device is set at 500-600mm, the water flow rate of the upper electrode tube in zone A is 100l / s, the water flow rate of the lower electrode tube is 120-150l / s, the water flow rate of the upper electrode tube in zone B is 280-300l / s, the water flow rate of the lower electrode tube is 340-450l / s, zones C and D are closed, the water-to-water ratio is controlled at 1:1.2-1.5, and the roller speed is 0.8-1.2m / s.

[0018] Based on the above technical solutions, the preferred steel plate thickness is >20-30mm, the frame height of the rapid cooling device is set to 600-700mm, the water flow rate of the upper tube in zone A is 100l / s, the water flow rate of the lower tube is 120-150l / s, the water flow rate of the upper tube in zone B is 300-320l / s, the water flow rate of the lower tube is 360-480l / s, the water flow rate of the upper tube in zone C is 300-320l / s, the water flow rate of the lower tube is 360-480l / s, zone D is closed, the water-to-water ratio is controlled at 1:1.2-1.5, and the roller speed is 0.8-1.2m / s.

[0019] Based on the above technical solutions, the preferred method is to use steel plates with a thickness greater than 30mm, with the frame height of the rapid cooling device set at 600-800mm, the water flow rate of the upper electrode tube in zone A being 100l / s and the water flow rate of the lower electrode tube being 120-150l / s, the water flow rate of the upper electrode tube in zone B being 300-320l / s and the water flow rate of the lower electrode tube being 360-480l / s, the water flow rate of the upper electrode tube in zone C being 300-320l / s and the water flow rate of the lower electrode tube being 360-480l / s, and the water flow rate of the upper electrode tube in zone D being 300-320l / s and the water flow rate of the lower electrode tube being 360-480l / s, the water-to-water ratio being controlled at 1:1.2-1.5, and the roller speed being 0.7-1.1m / s.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] By controlling the slab exit temperature, the roughing and finishing processes, the initial cooling temperature of the steel plate, and the cooling water volume and ratio according to the different thicknesses of the steel plate, and by straightening the plate, the production efficiency is improved by effectively avoiding warping, buckling, and edge waviness of the high-strength steel plate due to uneven temperature after rapid cooling. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] A production method for controlling the shape of TMCP high-strength steel plates in winter includes the following steps:

[0024] Step 1: Set the slab exit temperature to 1220℃~1270℃ and perform one coarse descaling.

[0025] Step 2: In the roughing stage, the overall reduction in the first 4 passes reaches 35% to 55%. Descaling of the roughing mill body is carried out in the 1st to 3rd passes. The final rolling temperature of the roughing mill is ≥1050℃.

[0026] Step 3: Finishing stage. For steel plates with a thickness of 10-20mm, the reduction in the last three passes is ≥6%, and the bending roll force is controlled at 3500-4200kN. The initial rolling temperature is ≥910℃, and a leveling pass is added after the final rolling. The reduction is 0-0.5mm, the rolling roll speed is 4.0-6.0m / s, and the final rolling temperature is ≥820℃. For steel plates with a thickness of >20-30mm, the initial rolling temperature is ≥900℃, and a leveling pass is added before the final pass. The reduction is 1.5-3mm, the rolling roll speed is 3.0-5.0m / s, and the final rolling temperature is ≥860℃. For steel plates with a thickness of >30mm, the initial rolling temperature is ≥900℃, the rolling roll speed in the last three passes is ≥3.0m / s, and the final rolling temperature is ≥860℃.

[0027] Step 4: The rolled steel plate undergoes pre-straightening treatment;

[0028] Step 5: For steel plates with a thickness of 10-20mm, the initial cooling temperature should be ≥780℃; for steel plates with a thickness of >20-30mm, the initial cooling temperature should be ≥810℃; for steel plates with a thickness of >30mm, the initial cooling temperature should be ≥820℃.

[0029] Step Six: Control the cooling water temperature of the rapid cooling device to 26±4℃. Install edge and head / tail shielding with steel plates 10-20mm thick. Set the frame height of the rapid cooling device to 500-600mm, divided into four zones: A, B, C, and D. Zone A: Upper tube water flow rate 100L / s, lower tube water flow rate 120-150L / s. Zone B: Upper tube water flow rate 280-300L / s, lower tube water flow rate... 340-450 l / s, zones C and D closed, water-to-water ratio controlled at 1:1.2-1.5, roller speed 0.8-1.2 m / s; for steel plates with a thickness >20-30 mm, the rapid cooling device frame height is set at 600-700 mm, water flow rate in zone A upper tube 100 l / s, water flow rate in zone B lower tube 120-150 l / s, water flow rate in zone B upper tube 300-320 l / s, water flow rate in zone B lower tube... Water flow rate: 360-480 l / s in zone C (upper tube 300-320 l / s, lower tube 360-480 l / s), zone D closed, water-to-water ratio controlled at 1:1.2-1.5, roller speed 0.8-1.2 m / s; for steel plates with a thickness >30 mm, the rapid cooling device frame height is set at 600-800 mm, water flow rate in zone A (upper tube 100 l / s, lower tube 120-1... 50 l / s, water flow rate of upper electrode tube in zone B: 300-320 l / s, water flow rate of lower electrode tube: 360-480 l / s; water flow rate of upper electrode tube in zone C: 300-320 l / s, water flow rate of lower electrode tube: 360-480 l / s; water flow rate of upper electrode tube in zone D: 300-320 l / s, water flow rate of lower electrode tube: 360-480 l / s; water-to-water ratio controlled at 1:1.2-1.5; roller speed 0.7-1.1 m / s;

[0030] Step 7: Final cooling temperature of the steel plate ≤ 300℃;

[0031] Step 8: Straighten the steel plate using a 9-roll hot straightener at a temperature of ≤350℃. The inlet roll gap of the straightener should be 2-9 mm less than the thickness of the steel plate. The straightening speed should be 0.5-1.0 m / s.

[0032] Table 1 below lists the steel grades, slab tapping temperatures, and roughing process control for each of the embodiments 1 to 6 of this invention;

[0033] Table 2 below lists the finishing rolling process control in each of the embodiments 1 to 6 of the present invention;

[0034] Table 3 below lists the cooling process control in each of the embodiments 1 to 6 of the present invention;

[0035] Table 4 below lists the parameter control of the rapid cooling device in embodiments 1 to 6 of the present invention;

[0036] Table 5 below lists the final cooling temperature of the steel plate, the straightening process control rolling, and the flatness of the steel plate in Examples 1 to 6 of the present invention.

[0037]

[0038] Table 1 lists the steel grades, slab tapping temperatures, and roughing process control for each of the embodiments 1 to 6 of this invention.

[0039]

[0040] Table 2 lists the finishing rolling process control in each of Embodiments 1 to 6 of the present invention.

[0041] Example Finished product width (mm) Finished product length (mm) Cooling temperature (°C) 1 2327 37810 799 2 3397 15403 805 3 3115 31527 834 4 2627 28804 829 5 2564 22245 846 6 3073 13490 824

[0042] Table 3 lists the cooling process control in each of Embodiments 1 to 6 of the present invention.

[0043]

[0044]

[0045] Table 4 lists the parameter control of the rapid cooling device in Embodiments 1-6 of the present invention.

[0046]

[0047] Table 5 lists the final cooling temperature of the steel plate, the straightening process control, and the flatness of the steel plate in Examples 1-6 of the present invention.

[0048] As shown in the table above, the high-strength steel plates with a thickness of 10-60mm implemented according to Tables 1-5 have a flatness of ≤3mm / m, good plate shape, and no defects such as central waviness, edge waviness, buckle, or warping.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of producing a shape of a high-strength steel plate for winter control TMCP, characterized by, Includes the following steps: Step 1: Set the slab exit temperature to 1220℃~1270℃ and perform one coarse descaling. Step 2: In the roughing stage, the overall reduction in the first 4 passes reaches 35% to 55%. Descaling of the roughing mill body is carried out in the 1st to 3rd passes. The final rolling temperature of the roughing mill is ≥1050℃. Step 3: Finishing stage, the reduction in the last 3 passes is ≥6%, and the bending roll force is controlled at 3500~4200kN. For steel plates with a thickness of 10~20mm, the initial rolling temperature is ≥910℃, and a leveling pass is added after the final rolling, with a reduction of 0~0.5mm, a rolling roll speed of 4.0~6.0m / s, and a final rolling temperature of ≥820℃. Step 4: The rolled steel plate undergoes pre-straightening treatment; Step 5: For steel plates with a thickness of 10-20mm, the initial cooling temperature should be ≥780℃; Step 6: The cooling water temperature of the rapid cooling device is controlled at 26±4℃. Side shielding and head and tail shielding are set up, and it is divided into four zones: A, B, C and D. The steel plate is 10-20mm thick. The frame height of the rapid cooling device is set to 500-600mm. The water flow rate of the upper tube in zone A is 100l / s and the water flow rate of the lower tube is 120-150l / s. The water flow rate of the upper tube in zone B is 280-300l / s and the water flow rate of the lower tube is 340-450l / s. Zones C and D are closed. The water-to-water ratio is controlled at 1:1.2-1.5, and the roller speed is 0.8-1.2m / s. For steel plates with a thickness greater than 20-30mm, the frame height of the rapid cooling device is set to 600-700mm. The water flow rate in the upper tube of zone A is 100l / s, and the water flow rate in the lower tube is 120-150l / s. The water flow rate in the upper tube of zone B is 300-320l / s, and the water flow rate in the lower tube is 360-480l / s. The water flow rate in the upper tube of zone C is 300-320l / s, and the water flow rate in the lower tube is 360-480l / s. Zone D is closed. The water-to-water ratio is controlled at 1:1.2-1.5, and the roller speed is 0.8-1.2m / s. For steel plates with a thickness greater than 30mm, the frame height of the rapid cooling device is set at 600-800mm. The water flow rate in the upper tube of zone A is 100l / s, and in the lower tube it is 120-150l / s. In zone B, the water flow rate in the upper tube is 300-320l / s, and in the lower tube it is 360-480l / s. In zone C, the water flow rate in the upper tube is 300-320l / s, and in the lower tube it is 360-480l / s. In zone D, the water flow rate in the upper tube is 300-320l / s, and in the lower tube it is 360-480l / s. The water-to-water ratio is controlled at 1:1.2-1.5, and the roller speed is 0.7-1.1m / s. Step 7: Final cooling temperature of the steel plate ≤ 300℃; Step 8: Straighten the steel plate using a 9-roll hot straightener at a temperature of ≤350℃. The inlet roll gap of the straightener should be 2-9 mm less than the thickness of the steel plate. The straightening speed should be 0.5-1.0 m / s.

2. The method of claim 1, wherein the method is characterized by: In the finishing rolling stage, for steel plates with a thickness of >20-30mm, the initial rolling temperature is ≥900℃, an additional leveling pass is added before the last pass, the reduction is 1.5-3mm, the rolling roll speed is 3.0-5.0m / s, and the final rolling temperature is ≥860℃.

3. The method of claim 1, wherein the method is characterized by: In the finishing rolling stage, for steel plates with a thickness >30mm, the initial rolling temperature is ≥900℃, the rolling speed of the last three passes is ≥3.0m / s, and the final rolling temperature is ≥860℃.

4. The method of claim 1, wherein the method is characterized by: For steel plates with a thickness of >20-30mm, the initial cooling temperature is ≥810℃; for steel plates with a thickness of >30mm, the initial cooling temperature is ≥820℃.

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