Method for preventing high alloy steel continuous casting billet head from warping

Abstract

The application relates to the technical field of metal casting, and discloses a continuous casting method for preventing the warping of a high-alloy steel continuous casting billet head, which comprises the following steps: step 10, a billet shell of high-alloy molten steel solidified in a crystallizer is pulled into a cooling area. Step 10 specifically comprises the following steps: step 11, the pulling speed of the billet shell is controlled to be 0.2 m / min to 0.33 m / min, and the pulling duration is 1 min to 3 min; step 12, the pulling speed of the billet shell is controlled to be increased to 0.35 m / min to 0.7 m / min within 5 min to 7 min; and step 13, the pulling speed of the billet shell is controlled to be increased to a high-speed pulling speed within 1 min to 3 min, and the high-speed pulling speed is 1 m / min to 1.2 m / min. Through the three-stage pulling speed control strategy of low-speed starting, rapid transition and high-speed running, the warping of the billet head is reduced, the cutting pass rate of the billet head is improved, and the metal utilization rate of the billet is improved.

Description

Technical Field

[0001] This application relates to the field of metal casting technology, and in particular to a continuous casting method for preventing warping of the billet head in high alloy steel continuous casting. Background Technology

[0002] High-alloy steels are characterized by high carbon (1.4% to 2.3%) and high alloy content (Cr content ≥12%, containing Mo, V, etc.), such as ledeburitic die steels (e.g., Cr12MoV, high-speed steel). Their solidification behavior differs significantly from ordinary steels. The high chromium content shifts the eutectic point of the Fe-C phase diagram to the left, easily forming a coarse eutectic ledeburite structure (containing network carbides) during solidification, resulting in uneven strength distribution in the billet shell. Simultaneously, the solidification shrinkage rate of high-alloy steels is 20% to 30% higher than that of ordinary steels, and carbide precipitation further exacerbates volume changes. For these reasons, the shrinkage difference at the billet head of high-alloy steel billets can cause a cross-sectional perpendicularity error of 1.5 mm / m to 2 mm / m, failing to meet the requirements for billet shape in subsequent rolling processes.

[0003] In related technologies, when high alloy steel is started up or when production is interrupted and restarted, the billet head often warps. The high warping makes it difficult to cut the billet and often results in subsequent rolling biting failure. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art or related technologies.

[0005] This application proposes a continuous casting method to prevent warping of the billet head in high-alloy steel continuous casting. The continuous casting method includes: step 10, pulling the billet shell solidified in the crystallizer into the cooling zone; step 20, cooling the billet shell in the cooling zone; and step 30, controlling a straightening machine to pull the cooled billet shell into the straightening zone. Step 20 and step 10 are performed simultaneously.

[0006] Step 10, which involves drawing the solidified high-alloy steel billet shell into the cooling zone, specifically includes: Step 11, controlling the drawing speed of the billet shell to be 0.2 m / min to 0.33 m / min, with a drawing duration of 1 minute to 3 minutes; Step 12, controlling the drawing speed of the billet shell to be increased to 0.35 m / min to 0.7 m / min within 5 minutes to 7 minutes; Step 13, controlling the drawing speed of the billet shell to be increased to a high-speed drawing speed of 1 m / min to 1.2 m / min within 1 minute to 3 minutes.

[0007] In some technical solutions provided in this application, step 12, which controls the drawing speed of the billet shell to increase to 0.35 m / min to 0.7 m / min within 5 to 7 minutes, specifically includes: step 121, controlling the drawing speed of the billet shell to increase to 0.35 m / min to 0.4 m / min within 1 to 3 minutes; and step 122, controlling the drawing speed of the billet shell to increase to 0.65 m / min to 0.7 m / min within 3 to 5 minutes.

[0008] In some of the technical solutions provided in this application, after step 13, which controls the drawing speed of the billet to be increased to a high-speed drawing speed within 1 to 3 minutes, the method further includes step 14, which controls the billet to be drawn out continuously at a high-speed drawing speed.

[0009] In some technical solutions provided in this application, the cooling zone includes a first cooling zone. The step 20 of cooling the billet shell in the cooling zone specifically includes: step 21, cooling the billet shell in the first cooling zone, wherein the specific water content of the first cooling zone is 0.48L / kg to 0.60L / kg.

[0010] In some technical solutions provided in this application, a second cooling zone is provided below the first cooling zone. The cooling path of the second cooling zone is arc-shaped. After step 21, which cools the billet shell in the first cooling zone, the application further includes step 22, which cools the billet shell in the second cooling zone. The specific water content of the second cooling zone is 0.48 L / kg to 0.60 L / kg.

[0011] In some technical solutions provided in this application, a third cooling zone is provided below the second cooling zone. The third cooling zone is connected to the straightening zone. After step 22, which cools the billet shell in the second cooling zone, the application further includes step 23, which cools the billet shell in the third cooling zone. The specific water content of the third cooling zone is 0.35 L / kg to 0.40 L / kg.

[0012] In some technical solutions provided in this application, step 30, which controls the tension leveler to pull the cooled billet into the straightening zone, specifically includes: step 31, determining the number of tension levelers to be started; and step 32, controlling at least four straightening rollers of any tension leveler to straighten both sides of the billet respectively.

[0013] In some technical solutions provided in this application, step 32, which controls at least four straightening rollers of any straightening machine to straighten both sides of the billet shell respectively, specifically includes: step 321, controlling the pressure of any straightening roller on the billet shell to be 10MPa to 11MPa.

[0014] In some technical solutions provided in this application, step 31, which determines the number of times the tension leveling machine is started, specifically includes: step 311, determining that the number of times the tension leveling machine is started is three.

[0015] In some technical solutions provided in this application, step 311, which determines the number of start-up tension levelers to be three, specifically includes: step 3111, controlling the spacing between adjacent tension levelers in the start-up state to be 0.4 m to 0.6 m.

[0016] Compared with related technologies, the present invention has at least the following beneficial effects:

[0017] By employing a three-stage speed control strategy—low-speed start, rapid transition, and high-speed operation—the precise speed control segmented casting process increases the surface temperature of high-alloy steel exiting the crystallizer, thereby increasing the surface temperature of the billet shell during continuous casting. This results in a more uniform internal temperature field distribution within the billet shell, reducing thermal stress concentration, minimizing billet head warping, and reducing the cutting difficulty caused by warping due to excessively low cutting point temperatures. This improves the billet head cutting throughput, increases the metal utilization rate of the billet, and reduces the manual intervention required to handle warped billet heads. Attached Figure Description

[0018] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of some embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0019] Figure 1 A flowchart illustrating steps 11 to 13 of a continuous casting method according to an embodiment of this application;

[0020] Figure 2 A schematic diagram illustrating the billet drawing speed of one embodiment provided in this application;

[0021] Figure 3 A schematic diagram of a continuous casting production line according to an embodiment of this application;

[0022] Figure 4 A schematic diagram of the straightening area provided in one embodiment of this application;

[0023] Figure 5 A schematic flowchart of the continuous casting method of Embodiment 1 provided in this application.

[0024] in, Figure 3 and Figure 4 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0025] 11. Liquid core; 12. Billet shell; 100. Crystallizer; 200. Cooling zone; 210. First cooling zone; 220. Second cooling zone; 230. Third cooling zone; 240. Nozzle; 300. Straightening zone; 400. Roller system; 410. Free roll; 420. Tension straightener; 500. Flame cutter. Detailed Implementation

[0026] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0027] Embodiments of this application provide a continuous casting method for preventing warping of the billet head in high-alloy steel continuous casting, such as... Figure 1 and Figure 2 As shown, the continuous casting method includes:

[0028] Step 10: Pull the solidified high-alloy steel billet shell in the crystallizer into the cooling zone.

[0029] Step 20: Cool the billet shell in the cooling zone;

[0030] Step 30: Control the tension leveler to pull the cooled billet shell into the straightening zone;

[0031] Step 20 and step 10 are executed simultaneously.

[0032] Step 10, which involves drawing the solidified high-alloy steel billet into the cooling zone, specifically includes:

[0033] Step 11: Control the drawing speed of the billet shell to be 0.2 m / min to 0.33 m / min, and the drawing duration to be 1 minute to 3 minutes;

[0034] Step 12: Control the drawing speed of the billet shell to increase to 0.35 m / min to 0.7 m / min within 5 to 7 minutes;

[0035] Step 13: Control the drawing speed of the billet shell to increase to a high-speed drawing speed within 1 to 3 minutes;

[0036] The high-speed pulling speed is 1m / min to 1.2m / min.

[0037] In this embodiment, after the high-alloy steel flowing from the tundish is injected into the crystallizer 100, it is cooled by the crystallizer 100 and solidifies into a billet shell 12 with a liquid core 11. The roller system 400 uses frictional force to continuously pull the billet shell 12 from the outlet of the crystallizer 100 into the cooling zone. The continuous casting system can control the pulling speed and pulling time of the billet shell 12 by controlling the rotational speed of the rollers in the roller system 400.

[0038] First, the billet shell is drawn at a slow speed of 0.2 m / min to 0.33 m / min for 1 to 3 minutes, marking the beginning of the low-speed start-up phase of the billet drawing operation. This ensures that the molten steel forms a sufficiently thick shell after exiting the crystallizer, preventing leakage. The slow drawing speed ensures sufficient solidification of the billet shell. Furthermore, once the shell reaches a safe thickness, the next stage begins immediately to prevent the shell from remaining in contact with the cold walls of the crystallizer for an extended period, thus reducing unnecessary heat dissipation.

[0039] Then, the drawing speed of the billet shell is increased to a medium-speed drawing speed of 0.35 m / min to 0.7 m / min within 5 to 7 minutes. The drawing operation enters a rapid transition phase, allowing the billet shell to gradually adapt to the increased drawing speed, ensuring the integrity of the billet shell structure, and avoiding cracks caused by sudden increases in drawing speed due to abrupt changes in internal and external temperature differences and stress concentration. Furthermore, the increase in drawing speed during the transition phase paves the way for the high-speed phase while avoiding prolonged heat dissipation of the billet shell at medium and low speeds.

[0040] Finally, the drawing speed of the billet shell is increased to a high-speed drawing speed of 1 m / min to 1.2 m / min within 1 to 3 minutes, and the drawing operation enters the high-speed stage. Compared with the conventional drawing speed of 0.5 m / min to 0.7 m / min, the drawing speed in the high-speed stage is increased. After the solidification of the first two stages, the thickness of the billet shell has reached a safe value. The high-speed drawing speed allows the billet shell, which has formed a sufficiently strong shell, to quickly leave the cooling environment, lock in the high temperature of the billet shell surface, reduce the heat loss from the contact between the billet shell surface and the cooling zone, and ensure that the surface temperature of the billet shell can be stabilized above 950℃ when it exits the crystallizer.

[0041] When the billet drawing speed is increased, the acceleration can remain constant, making the drawing speed increase linearly, or the acceleration can be changed, making the drawing speed increase curvilinearly.

[0042] By employing a three-stage speed control strategy—low-speed start, rapid transition, and high-speed operation—the precise speed control segmented casting process increases the surface temperature of high-alloy steel exiting the crystallizer, thereby increasing the surface temperature of the billet shell during continuous casting. This results in a more uniform internal temperature field distribution within the billet shell, reducing thermal stress concentration, minimizing billet head warping, and reducing the cutting difficulty caused by warping due to excessively low cutting point temperatures. This improves the billet head cutting throughput, increases the metal utilization rate of the billet, and reduces the manual intervention required to handle warped billet heads.

[0043] For example, the slow pull speed can be 0.3 m / min, the duration of the slow pull speed can be 2 minutes, the ramp-up time of the medium pull speed can be 6 minutes, and the ramp-up time of the high pull speed can be 2 minutes.

[0044] In some embodiments provided in this application, step 12, which controls the drawing speed of the billet to increase to 0.35 m / min to 0.7 m / min within 5 to 7 minutes, specifically includes:

[0045] Step 121: Control the drawing speed of the billet shell to increase to 0.35 m / min to 0.4 m / min within 1 to 3 minutes;

[0046] Step 122: Control the drawing speed of the billet shell to increase to 0.65 m / min to 0.7 m / min within 3 to 5 minutes.

[0047] In this embodiment, the medium-speed transition stage is divided into two-stage gradient control. First, in the early stage of the transition stage, the billet speed is increased to 0.35 m / min to 0.4 m / min. At this stage, the billet shell has just completed the initial slow solidification, and the overall strength is still low. After flowing out of the crystallizer, the billet shell enters the cooling zone at a slower speed, providing more sufficient cooling and solidification time for the billet shell. This ensures a smooth transition of the billet shell from the critical safety thickness to the high strength thickness, and in particular, avoids the problem of local solidification lag and thinness in areas with uneven heat dissipation, such as the edges and corners of the billet shell and surface depressions. This lays the foundation for a uniform billet shell across the entire cross-section for subsequent high-speed drawing.

[0048] Then, in the later stage of the transition phase, the drawing speed is increased to 0.65 m / min to 0.7 m / min. After the uniform thickening of the billet shell in the early stage, it has a certain stress resistance. At this time, increasing the drawing speed can reduce the excessive residence of the billet shell in the cooling zone, which can both ensure that the billet shell continues to thicken and maintain the surface temperature of the billet shell, so as to make a good temperature transition for the billet shell to enter the high-speed stage.

[0049] By using gradient design, the rate of change of drawing speed is controlled within an extremely low range. Through precise control of solidification rhythm and stress adaptation, the quality of the billet shell and the efficiency of the subsequent high-speed stage are further optimized. This allows the billet shell to gradually adapt to the stress changes brought about by the increase in drawing speed through slow plastic deformation, reducing stress concentration and the probability of defects such as cracks. This provides a more reliable guarantee for the safe execution of subsequent high-speed drawing and the stable achievement of surface high temperature.

[0050] In some embodiments provided in this application, after step 13, which controls the drawing speed of the billet to increase to a high-speed drawing speed within 1 to 3 minutes, the method further includes:

[0051] Step 14: Control the billet to maintain a high-speed drawing rate and continue drawing it out.

[0052] In this embodiment, a method for pulling the billet shell after three-stage casting speed is provided. The billet shell is continuously pulled out at a high speed and enters a stable production stage. This shortens the contact time between the billet shell and the cooling medium after it is pulled out of the crystallizer, reduces excessive heat loss from the surface of the billet shell, stably maintains the high-temperature foundation laid in the previous stage, ensures the high surface temperature state of the billet shell, meets the stringent requirements of high alloy steel for surface temperature and structural integrity, and realizes efficient continuous casting production.

[0053] In some embodiments provided in this application, such as Figure 3 As shown, the cooling zone 200 includes a first cooling zone 210. The step 20 of cooling the billet shell in the cooling zone specifically includes:

[0054] Step 21: Cool the billet shell in the first cooling zone. The specific water volume in the first cooling zone is 0.48L / kg to 0.60L / kg.

[0055] In this embodiment, a cooling method for the billet shell in a first cooling zone is provided. A cooling zone 200 is provided downstream of the crystallizer 100, and a spray manifold and nozzles 240 are provided in the cooling zone 200. The billet shell 12 is cooled by air and cooling water sprayed from the nozzles 240. The continuous casting system can control the specific water volume of the cooling zone 200 by controlling the water output of the nozzles 240. The first cooling zone 210 of the cooling zone 200 is adjacent to the outlet of the crystallizer 100 and is located in the first support area below the outlet of the crystallizer 100. The first cooling zone 210 can be a foot roll area.

[0056] Compared to the specific water content of 0.40 L / kg to 0.50 L / kg in related technologies, by increasing the specific water content in the first cooling zone, the cooling curvature of the billet shell is improved, the initial solidification rate of the billet shell is accelerated, and the precipitation of large-sized carbides is reduced.

[0057] In some embodiments provided in this application, such as Figure 3 As shown, a second cooling zone 220 is provided below the first cooling zone 210. The cooling path of the second cooling zone 220 is arc-shaped. After step 21 of cooling the billet shell in the first cooling zone, the following steps are also included:

[0058] Step 22: Cool the billet shell in the second cooling zone. The water content in the second cooling zone is 0.48 L / kg to 0.60 L / kg.

[0059] In this embodiment, a cooling method for the billet shell in the second cooling zone is provided. The roller system device 400 includes free rollers 410, and the second cooling zone 220 is located downstream of the first support area in the area of ​​the widely spaced free rollers 410. The free rollers 410 in the second cooling zone 220 are arranged in an arc shape, which forms a curved section of the billet shell 12 to change the direction of the drawing. The second cooling zone 220 corresponds to the first half of the curved section of the billet shell 12.

[0060] Compared with related technologies, this application increases the specific water volume of the second cooling zone, improves the cooling degree of the billet shell when turning, and realizes the upper strong cooling method through the first and second cooling zones, so that the cooling rate can be increased from 1.5℃ / s to 3℃ / s, and the size and quantity of Cr7C3 precipitation are reduced under high cooling rate.

[0061] In some embodiments provided in this application, such as Figure 3 As shown, a third cooling zone 230 is provided below the second cooling zone 220. The third cooling zone 230 is connected to the straightening zone 300. After step 22, which cools the billet shell in the second cooling zone, the following steps are also included:

[0062] Step 23: Cool the billet shell in the third cooling zone. The water content in the third cooling zone is 0.35L / kg to 0.40L / kg.

[0063] In this embodiment, a cooling method for the billet shell in a third cooling zone is provided. The third cooling zone 230 is located downstream of the second cooling zone 220 in the area of ​​the free rollers 410 with a larger roller diameter. The free rollers 410 in the third cooling zone 230 are arranged in an arc shape, so that the third cooling zone 230 corresponds to the latter half of the curved section of the billet shell 12 and is adjacent to the straightening zone 300.

[0064] Compared with related technologies, this application reduces the specific water volume of the third cooling zone and achieves a weak cooling method in the lower part through the third cooling zone. This keeps the billet temperature at a high temperature before entering the straightening zone. The billet temperature can be maintained above 900°C when passing through the straightening zone. The high plasticity of the billet at high temperature offsets the straightening stress, thereby avoiding the third brittle zone and reducing crack sensitivity. This prevents the billet from being subjected to external forces in the brittle temperature range and causing cracks, thus ensuring the continuous casting quality of high alloy steel.

[0065] In some embodiments provided in this application, such as Figure 3 As shown, step 30, which involves controlling the tension leveler to pull the cooled billet into the straightening zone, specifically includes:

[0066] Step 31: Determine the number of tension leveling machines to be started;

[0067] Step 32: Control at least four straightening rollers of any straightening machine to straighten both sides of the billet shell respectively.

[0068] In this embodiment, a method for straightening the billet shell is provided. The roller system device 400 also includes a tension straightener 420, which is provided within the straightening zone 300. Each tension straightener 420 has four straightening rollers, forming a four-roll tension straightener 420, with the four straightening rollers arranged in pairs facing each other. A flame cutter 500 downstream of the straightening zone 300 is used to cut the straightened billet.

[0069] After the billet enters the straightening zone, four straightening rollers evenly straighten both sides of the billet, improving the straightening force and straightening uniformity of the billet. This allows the stress applied by the straightening rollers to better constrain the natural deformation trend of the billet head and reduce the plastic deformation of the billet head.

[0070] In some embodiments provided in this application, such as Figure 4 As shown, step 32, which involves controlling at least four straightening rollers of any straightening machine to straighten both sides of the billet shell respectively, specifically includes:

[0071] Step 321: Control the pressure of any straightening roller on the billet shell to be between 10 MPa and 11 MPa.

[0072] In this embodiment, compared to the 7MPa to 8MPa pressure applied to the hot billet in related technologies, this application reasonably increases the pressure applied by the straightening rollers, ensuring that the stress applied during the straightening process is precisely matched with the strength of the solidified billet shell at this stage, so that the stress applied by the straightening rollers can better constrain the natural deformation trend of the billet head and improve the continuous casting quality of the steel body.

[0073] In some embodiments provided in this application, such as Figure 4 As shown, step 31, which determines the number of times the tension leveler will be started, specifically includes:

[0074] Step 311: Determine the number of times the tension leveling machine can be started: three.

[0075] In this embodiment, a specific arrangement of the straightening machines is provided. Three four-roll straightening machines are sequentially arranged along the billet conveying path, forming a three-stage configuration. The first straightening machine is the preliminary straightening stage for "bending reduction," eliminating significant warping of the billet shell and establishing its basic straightness. The second straightening machine is the main straightening stage for "stress relief," eliminating residual deformation within the billet shell and improving its overall straightness. The third straightening machine is the fine straightening stage for "shaping," controlling the final accuracy of the billet shell to meet the requirements of subsequent processes. This three-stage arrangement of the straightening machines achieves functional layering of the straightening operation. Through the progressive process of rough straightening, main straightening, and fine straightening, a staged straightening operation is achieved, reducing billet shell deformation and improving the final straightening effect.

[0076] In some embodiments provided in this application, step 311, which determines the number of times the straightening machine is started as three, specifically includes:

[0077] Step 3111: Control the spacing between adjacent tension leveling machines in the start-up state to be 0.4 m to 0.6 m.

[0078] In this embodiment, the spacing A between adjacent straighteners can be 0.5m. Compared with the spacing of 1m to 1.2m in related technologies, this application shortens the arrangement spacing of the straighteners, making the straightening pressure on the billet shell more closely distributed, the straightening effect more uniform, and further improving the straightening effect of the billet shell.

[0079] In a specific embodiment 1, the continuous casting method for preventing warping of the billet head in high-alloy steel continuous casting is as follows: Figure 5 As shown, firstly, the billet shell solidified in the crystallizer is pulled into the cooling zone, and the billet shell in the cooling zone is cooled. During this process, the continuous casting system simultaneously controls the billet shell pulling speed and the specific water content of the billet shell in the cooling zone. The two control processes are independent of each other.

[0080] Regarding the control of the billet shell drawing speed, firstly, the billet shell drawing speed is 0.3 m / min for the first 2 minutes. Then, from 2 to 4 minutes, the billet shell drawing speed is increased to 0.35 m / min to 0.4 m / min. From 4 to 8 minutes, the billet shell drawing speed is increased to 0.65 m / min to 0.7 m / min. From 8 to 10 minutes, the billet shell drawing speed is increased to 1 m / min to 1.2 m / min. Finally, the billet shell is produced at a stable drawing speed.

[0081] Regarding the control of the specific water content of the billet in the cooling zone, firstly, the specific water content in the foot roll zone is 0.48 L / kg to 0.60 L / kg; then, the specific water content in the second cooling zone is 0.48 L / kg to 0.60 L / kg; and finally, the specific water content in the third cooling zone is 0.35 L / kg to 0.40 L / kg. The foot roll zone and the second cooling zone employ strong cooling, while the third cooling zone before entering the straightening zone employs weak cooling.

[0082] After the billet shell exits the cooling zone, the controlled tension leveler pulls the cooled billet shell into the straightening zone. The three four-roll tension levelers are spaced 0.5m apart, and the straightening roll pressure is 10MPa. By replacing the traditional two-roll tension leveler with a four-roll configuration, and through precise control of temperature, pulling speed, and pressure, warping of the billet head in ledeburitic mold steel continuous casting is effectively prevented. This is suitable for scenarios requiring precise quality control of high-alloy steel continuous casting billets.

[0083] Warped portions, unable to meet the requirements of subsequent processing (such as rolling, tension leveling, shearing, etc.), are typically removed as scrap in advance. After implementing this process, the warpage height of the billet head decreased from 18mm-20mm to 7mm-9mm, achieving a 100% cutting pass rate. Geometric dimension testing of the billet head showed a cross-sectional perpendicularity error ≤1mm / m, meeting the requirements for billet shape in subsequent rolling. The metal utilization rate of a single billet increased by approximately 14%. Handling warped billet heads requires additional manual intervention (such as manual straightening, adjusting billet position, and cleaning up scrap). If 100 warped billets are processed daily, 2-3 dedicated personnel are needed, resulting in high labor costs. Reducing warpage allows for automated billet flow, reducing manual intervention by over 80% and directly saving labor costs.

[0084] In a specific embodiment 2, the billet drawing speed is 0.3 m / min for the first 2 minutes after casting, increasing to 0.35 m / min from 2 to 4 minutes, 0.65 m / min from 4 to 8 minutes, and 1 m / min from 8 to 10 minutes, with a stable drawing speed of 1 m / min thereafter. The specific water content in the foot roll zone and the second cooling zone is 0.50 L / kg, and a weak cooling method is used before entering the straightening zone to reduce the specific water content to 0.37 L / kg. The traditional two-roll straightener is replaced with a four-roll configuration, the distance between straighteners is shortened to 0.5 m, and the straightening roll pressure is 10.2 MPa. The head billet warpage is 8 mm, and the cross-sectional perpendicularity error is ≤1 mm / m, meeting the rolling requirements.

[0085] In a specific embodiment 3, the billet drawing speed is 0.3 m / min for the first 2 minutes after casting, increasing to 0.4 m / min from 2 to 4 minutes, 0.7 m / min from 4 to 8 minutes, and 1.1 m / min from 8 to 10 minutes, with a stable drawing speed of 1.1 m / min thereafter. The specific water content in the foot roll zone and the second cooling zone is 0.52 L / kg, which is reduced to 0.38 L / kg by a weak cooling method before entering the straightening zone. The traditional two-roll straightener is replaced with a four-roll configuration, the distance between straighteners is shortened to 0.5 m, and the straightening roll pressure is 10.3 MPa. The head billet warpage is 4 mm, and the cross-sectional perpendicularity error is ≤1 mm / m, meeting the rolling requirements.

[0086] In a specific embodiment 4, the billet drawing speed is 0.3 m / min for the first 2 minutes after casting, increasing to 0.3 m / min from 2 to 4 minutes, 0.7 m / min from 4 to 8 minutes, and 1.1 m / min from 8 to 10 minutes. The billet is then drawn at a stable speed of 1.1 m / min. The water content in the foot roll zone and the second cooling zone is 0.58 L / kg. Before entering the straightening zone, a weak cooling method is used to reduce the water content to 0.35 L / kg. The traditional two-roll straightener is replaced with a four-roll configuration, the distance between straighteners is shortened to 0.5 m, and the straightening roll pressure is 10 MPa. The head billet warpage is 6 mm, and the cross-sectional perpendicularity error is ≤1 mm / m, meeting the rolling requirements.

[0087] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0088] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0089] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0090] The above are merely some embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A continuous casting method for preventing warping of the billet head in high-alloy steel continuous casting, characterized in that, The continuous casting method includes: Step 10: Pull the solidified high-alloy steel billet shell in the crystallizer into the cooling zone. Step 20: Cool the blank shell in the cooling zone; Step 30: Control the tension leveler to pull the cooled billet shell into the straightening zone; Step 20 and step 10 are performed simultaneously; step 10, which involves pulling the solidified high-alloy steel billet shell in the crystallizer into the cooling zone, specifically includes: Step 11: Control the drawing speed of the billet shell to be 0.2 m / min to 0.33 m / min, and the drawing duration to be 1 minute to 3 minutes; Step 12: Control the drawing speed of the billet shell to increase to 0.35 m / min to 0.7 m / min within 5 to 7 minutes; Step 13: Control the drawing speed of the billet shell to increase to a high-speed drawing speed within 1 to 3 minutes; The high-speed pulling speed is 1 m / min to 1.2 m / min; Step 12, which involves controlling the drawing speed of the billet to increase to 0.35 m / min to 0.7 m / min within 5 to 7 minutes, specifically includes: Step 121: Control the drawing speed of the billet shell to increase to 0.35 m / min to 0.4 m / min within 1 to 3 minutes; Step 122: Control the drawing speed of the billet shell to increase to 0.65 m / min to 0.7 m / min within 3 to 5 minutes; After step 13, which involves increasing the drawing speed of the billet to a high-speed drawing speed within 1 to 3 minutes, the method further includes: Step 14: Control the billet to maintain the high-speed drawing speed and continue drawing it out.

2. The continuous casting method for preventing warping of the billet head in high-alloy steel continuous casting according to claim 1, characterized in that, The cooling zone includes a first cooling zone, and step 20, which involves cooling the billet shell within the cooling zone, specifically includes: Step 21: Cool the billet shell in the first cooling zone, wherein the water content of the first cooling zone is 0.48 L / kg to 0.60 L / kg.

3. The continuous casting method for preventing warping of the billet head in high-alloy steel continuous casting according to claim 2, characterized in that, A second cooling zone is provided below the first cooling zone, and the cooling path of the second cooling zone is arc-shaped. After step 21 of cooling the blank shell in the first cooling zone, the method further includes: Step 22: Cool the billet shell in the second cooling zone, wherein the water content of the second cooling zone is 0.48 L / kg to 0.60 L / kg.

4. The continuous casting method for preventing warping of the billet head in high-alloy steel continuous casting according to claim 3, characterized in that, A third cooling zone is provided below the second cooling zone, and the third cooling zone is connected to the straightening zone. After step 22 of cooling the billet shell in the second cooling zone, the method further includes: Step 23: Cool the billet shell in the third cooling zone, wherein the water content of the third cooling zone is 0.35L / kg to 0.40L / kg.

5. The continuous casting method for preventing warping of the billet head in high-alloy steel continuous casting according to claim 1, characterized in that, Step 30, in which the controlled tension straightener pulls the cooled billet into the straightening zone, specifically includes: Step 31: Determine the number of times the tension leveling machine can be started; Step 32: Control at least four straightening rollers of any of the straightening machines to straighten both sides of the billet shell respectively.

6. The continuous casting method for preventing warping of the billet head in high-alloy steel continuous casting according to claim 5, characterized in that, Step 32, which involves controlling at least four straightening rollers of any of the straightening machines to straighten both sides of the billet shell, specifically includes: Step 321: Control the pressure of any of the straightening rollers on the billet shell to be 10 MPa to 11 MPa.

7. The continuous casting method for preventing warping of the billet head in high-alloy steel continuous casting according to claim 5, characterized in that, Step 31, which determines the number of times the tension straightening machine will be started, specifically includes: Step 311: Determine that the number of times the tension straightening machine is started is three.

8. The continuous casting method for preventing warping of the billet head in high-alloy steel continuous casting according to claim 7, characterized in that, Step 311, which determines that the number of starts of the tension straightening machine is three, specifically includes: Step 3111: Control the spacing between adjacent tension leveling machines in the start-up state to be 0.4m to 0.6m.

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