Method for producing high alloy steel by continuous casting

Abstract

This application discloses a method for continuously casting high-alloy steel, comprising: reducing the specific water content of the high-alloy steel continuously cast billet at the casting speed during billet production; setting the roll gap of the driven roller in the fan-shaped section after the light down-pressing section to a parallel roll gap or an open roll gap, while keeping the reduction amount of the light down-pressing section unchanged; and setting the maximum pressure of the first hydraulic cylinder in the fan-shaped section after the light down-pressing section to below 160 bar. By reducing the specific water content of the high-alloy steel continuously cast billet at each casting speed during production, the cooling intensity of the continuously cast billet is reduced, thereby increasing the temperature of the continuously cast billet and reducing the strength of the billet shell and the continuously cast billet; by reducing the total reduction amount of the roll gap in the fan-shaped section and the maximum pressure of the first hydraulic cylinder, the normal pressure of the fan-shaped section on the billet shell and the continuously cast billet is reduced, thereby reducing the average torque of the drive roller; solving the problem of the continuously cast billet being unable to be drawn during the production of high-alloy steel continuously cast billets, reducing the occurrence rate of billet being unable to be drawn to 0 times / heat of molten steel, and increasing the service life of the fan-shaped section to more than 6500 heats of molten steel.

Description

Technical Field

[0001] This application belongs to the field of high alloy steel manufacturing technology, and particularly relates to a method for continuous casting to produce high alloy steel. Background Technology

[0002] The primary function of the sector section in a continuous casting machine is to support and guide the billet, which has initially formed with a certain shell thickness in the crystallizer, and to provide forced water cooling, ensuring that the shell thickness continues to increase without causing excessive "bulging" strain or leakage due to the static pressure of the molten steel. The surface temperature of the continuously cast billet in the sector section is between 700℃ and 1000℃. Most continuous casting machines are not designed to produce a single type of steel; they may produce some high-alloy steel while producing ordinary steel. Referring to Table 1, compared to ordinary steel, high-alloy steel has a strength 1-2 times greater at high temperatures. Since the driven or assisted rolls in the sector section are generally cooled internally by water, when producing high-alloy steel, the driven or assisted rolls are prone to breakage and leakage at the bearing housing due to the extreme pressure exerted by the high strength of the high-alloy steel. Furthermore, the hydraulic cylinder used to control the driven roller in the sector section will generate high pressure and high drive roller torque. In severe cases, it will lead to poor roller gap accuracy in the sector section and the inability to pull the billet. This reduces the average service life of the sector section of the continuous casting machine for producing high alloy steel from producing 6,800 heats of molten steel to 3,500 heats of molten steel, a reduction of more than 50%.

[0003] Table 1. Strength of various steel grades at different high temperatures, N*mm -2

[0004] Brand 700℃ 800℃ 900℃ 1000℃ 20# steel (ordinary steel) 119 81 55 44 8MN14 300 210 140 110 2Cr13 325 196 127 84 5MN24 206 132 89 61 00Cr17Ni14Mo2 280 210 137 82 1Cr18Ni12Mo3TI 460 240 146 66 Summary of the Invention

[0005] This application provides a method for continuous casting of high alloy steel, which can solve the problems of poor roll gap accuracy in the sector section, inability to pull the continuous casting billet, and shortened service life of the sector section when producing high alloy steel continuous casting billets.

[0006] In a first aspect, this application provides a method for continuously casting high-alloy steel, comprising: reducing the specific water content of the high-alloy steel billet at the casting speed during the continuous casting billet production process to increase the temperature of the billet in the sector section; setting the roll gap of the driven roll in the sector section after the light pressing section to a parallel roll gap or an open roll gap to reduce the total pressing amount of the driven roll and keep the pressing amount of the light pressing section unchanged; setting the maximum pressure of the first hydraulic cylinder in the sector section after the light pressing section to below 160 bar to reduce the pressure of the billet on the sector section.

[0007] According to an embodiment of the first aspect of this application, during the production of continuously cast billets, the casting speed of the high alloy steel continuously cast billets is 0.5 m / min to 1.3 m / min.

[0008] According to an embodiment of the first aspect of this application, during the continuous casting billet production process, the casting speed of the high alloy steel continuous casting billet is 0.8 m / min to 1.2 m / min.

[0009] According to an embodiment of the first aspect of this application, in the process of producing a continuous casting billet, the step of reducing the specific water content of the high alloy steel continuous casting billet at the casting speed to increase the temperature of the continuous casting billet in the sector section further includes: selecting weak cooling during the secondary cooling process of the continuous casting billet to reduce the cooling intensity of the continuous casting billet.

[0010] According to an embodiment of the first aspect of this application, the specific water content of the high alloy steel continuous casting billet at the casting speed is 0.26 L / kg to 0.48 L / kg.

[0011] According to an embodiment of the first aspect of this application, the specific water content of the high alloy steel continuous casting billet at the casting speed is 0.29 L / kg to 0.42 L / kg.

[0012] According to the embodiments of the first aspect of this application, the casting speed and specific water content of the continuous casting billet of high alloy steel satisfy the following corresponding relationships: 0.5m / min-0.26L / Kg steel, 0.6m / min-0.29L / Kg steel, 0.7m / min-0.32L / Kg steel, 0.8m / min-0.36L / Kg steel, 0.9m / min-0.38L / Kg steel, 1.0m / min-0.41L / Kg steel, 1.1m / min-0.44L / Kg steel, 1.2m / min-0.46L / Kg steel, and 1.3m / min-0.48L / Kg steel.

[0013] According to the embodiment of the first aspect of this application, in the step of setting the roll gap of the driven roller in the sector section after the light pressing to a parallel roll gap or an open roll gap to reduce the total pressing amount of the driven roller in the sector section, the total pressing amount of the driven roller is reduced to 6.8mm to 8.8mm, the total pressing amount is reduced by 4.2mm to 2.2mm, and the pressing amount of the light pressing section remains unchanged.

[0014] According to an embodiment of the first aspect of this application, the maximum pressure of the first cylinder in the fan-shaped section following the light pressing section is set to 60 bar to 160 bar.

[0015] According to an embodiment of the first aspect of this application, the maximum pressure of the first cylinder in the fan-shaped section following the light pressing section is set to 60 bar to 100 bar.

[0016] According to an embodiment of the first aspect of this application, the maximum pressure of the first cylinder in the fan-shaped section following the light downward pressure section is set to 120 bar to 160 bar.

[0017] According to an embodiment of the first aspect of this application, the sector segment includes a drive roller and a driven roller, and the roller gap between the grouped drive rollers and the grouped driven rollers is equal or has an error of ≤2%.

[0018] The method for continuous casting of high-alloy steel according to embodiments of this application reduces the specific water content of the high-alloy steel continuous casting billet at various casting speeds during the billet production process. This reduces the cooling rate and cooling intensity of the billet, increases the temperature of the billet within the sector section, reduces the strength of the billet shell and the billet itself, and adjusts the correspondence between casting speed and roll gap table to control the internal quality of the billet. The average torque of the drive rolls in the sector section is reduced from 5250 N*m to 6360 N*m to 1800 N*m to 2375 N*m. Furthermore, it solves the problem of the billet being unable to be drawn during the production of high-alloy steel continuous casting billets, reducing the occurrence rate of this problem from 0.083 times / heat of molten steel to 0 times / heat of molten steel. Through these process improvements, the service life of the sector section is increased from producing 3500 heats of molten steel before the improvement to producing more than 6500 heats of molten steel after the improvement. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a structural diagram of the main equipment for the slab continuous casting process in this application.

[0021] Figure 2 This is a flowchart illustrating a method provided in one embodiment of this application.

[0022] Figure 3 This is a simplified process flow diagram of the slab continuous casting process of this application.

[0023] Figure 4 This is a simplified process flow diagram of the slab continuous casting process of this application.

[0024] Figure 5 This is a schematic diagram showing the relative positions of the first hydraulic cylinder, the second hydraulic cylinder, the frame, the drive roller, and the driven roller in a partial sector of this application.

[0025] Explanation of reference numerals in the attached drawings: 1. Rotary tower; 2. Ladle; 200. First outlet; 3. Intermediate ladle; 300. Second outlet; 4. Sector section; 40a. Inlet; 40b. Outlet; 41. Frame; 410. First hydraulic cylinder; 42. Drive roller; 420. Second hydraulic cylinder; 43. Driven roller; d. Roll gap; 5. Crystallizer; 6. Continuous casting billet. Detailed Implementation

[0026] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0027] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0028] In continuous casting equipment, a single continuous casting machine constituting a continuous casting line is generally called a sector section. A sector section is typically divided into an arc section (or curved section), a straightening section, and a horizontal section. Based on the type of continuously cast billet, a sector section can be further divided into a slab sector section, a square billet sector section, and a round billet sector section, with slab sector sections and square billet sector sections being the most common. The sector section uses drive rollers and driven rollers mounted on each sector section to pull out the continuously cast billet and straighten it into a slab. The sector section also guides and holds the dummy bar for casting and billet pulling. A complete sector section mainly consists of an inner arc structure, an outer arc structure, roller mounting equipment (including drive rollers and free wheels, also called driven rollers), clamping and guiding equipment, drive roller pressing equipment, roller gap adjustment equipment, and water cooling, lubrication, and hydraulic piping.

[0029] As mentioned in the background section, when producing high-alloy steel, the sector section of the continuous casting machine suffers from high cylinder pressure and large drive roller torque, which in severe cases can even lead to poor roller gap precision and difficulty in pulling the continuously cast billet. The inventors of this application addressed the problem of excessive drive roller torque in high-alloy steel production by reducing the cooling intensity of the continuous casting billet within the sector section and by adjusting the roller gap design of the sector section. This reduced the average pressure of the cylinders in each sector section from 132 Bar to 65 Bar, and the average torque of the drive rollers from 5250 N*m~6360 N*m to 1800 N*m~2375 N*m. It also solved the problem of significant equipment damage during high-alloy steel production in continuous casting machines. Furthermore, because the roller gap in sector section 4 is position-controlled, a smaller roller gap reduction results in lower pressure in the first cylinder of the sector section, leading to less resistance in billet pulling. If the roll gap is large, the pressure of the first cylinder in the sector section will be high, the resistance to billet pulling will be high, and the continuously cast billet will not be able to be pulled.

[0030] It should be noted that the torque of the drive roller refers to the torque of the drive roller in the sector section of the continuous casting machine. It is the "rotational force" required to overcome the weight of the continuously cast billet, bending force, friction, and dynamic load. It is determined by the coefficient of friction, the normal force, and the radius of the drive roller. The torque calculation formula is:

[0031] Torque (T) = Coefficient of friction (μ) × Normal force (N) × Drive roller radius (r)

[0032] Wherein, the coefficient of friction (μ) represents the ratio between the frictional force on the continuously cast billet shell on the drive roller and the force acting on the drive roller; the normal force (N) refers to the vertical force exerted by the drive roller on the continuously cast billet shell. The drive roller is connected to and driven by an externally mounted motor and a universal joint connecting rod, which is not shown in the attached drawing.

[0033] To address the problems of the prior art, this application provides a method for producing high-alloy steel by continuous casting. The method for producing high-alloy steel by continuous casting provided in this application will be described below.

[0034] Figure 1 This application shows a schematic diagram of the main equipment structure for a slab continuous casting process according to an embodiment of the present application. Figure 2 A schematic flow diagram of a method for continuous casting production of high-alloy steel according to an embodiment of this application is shown. Figures 2 to 5As shown, a method for producing high-alloy steel by continuous casting includes: reducing the specific water content of the high-alloy steel continuous casting billet 6 at the casting speed during the production of the continuous casting billet 6, so as to increase the temperature of the continuous casting billet 6 in the sector section 4; setting the roll gap d of the driven roller 43 in the sector section 4 after the light pressing section to a parallel roll gap or an open roll gap, so as to reduce the total pressing amount of the driven roller 43 and keep the pressing amount of the light pressing section unchanged; setting the maximum pressure of the first hydraulic cylinder 410 in the sector section 4 after the light pressing section to below 160 bar, so as to reduce the pressure of the continuous casting billet 6 on the sector section 4.

[0035] The method for continuous casting of high-alloy steel provided in this application reduces the specific water content of the high-alloy steel continuous casting billet 6 at various casting speeds during the production process, thereby reducing the cooling intensity of the billet 6 and increasing the temperature of the billet 6 within the sector section 4, thus reducing the mechanical strength of the billet 6. Furthermore, by adjusting the correspondence between the casting speed and the roll gap table, the internal quality of the billet 6 is controlled. The average torque of the drive roller 42 in the sector section 4 is reduced from 5250 N*m to 6360 N*m to 1800 N*m to 2375 N*m. This also solves the problem of the billet 6 being unable to be drawn during the production of high-alloy steel, reducing the occurrence rate of this problem from 0.083 times / heat of molten steel to 0 times / heat of molten steel. Through these process improvements, the service life of the sector section 4 is increased from producing 3500 heats of molten steel before the improvement to producing over 6500 heats of molten steel after the improvement.

[0036] It should be noted that the specific water content in the method for producing high-alloy steel by continuous casting provided in this application embodiment refers to the specific water content applicable to the entire sector section 4. The method for producing high-alloy steel by continuous casting provided in this application embodiment is suitable for producing high-alloy steel with manganese content ≥6%, C content ≥0.5%, aluminum content ≥1.5%, Mo content ≥1.0%, and Cr content ≥12.5%, whether single-element or multi-element composite addition. The light reduction section is used to improve the center segregation of the continuously cast billet. At the solidification end of the continuously cast billet, the roll gap shrinkage of the corresponding sector section is controlled to be larger. The typical roll gap shrinkage is 0.2mm to 0.3mm, while the roll gap shrinkage in the light reduction section is 1.5mm to 4.0mm. The position of the solidification end is related to the casting speed, molten steel superheat, and steel grade, and can be determined according to the corresponding steel grade. The pressure of the first hydraulic cylinder 410 before and during the light reduction section remains constant at 200 bar. The maximum pressure of the first cylinder 410 in the sector section 4 after the light pressing section is set to below 160 bar to reduce the pressure of the continuous casting billet 6 on the sector section 4 and prevent the roll gap deviation (equipment accuracy) of the sector section after the light pressing section from causing the first cylinder pressure of the sector section to be high when producing high alloy steel.

[0037] In some embodiments, during the production of the continuously cast billet 6, the casting speed of the high-alloy steel billet 6 is 0.5 m / min to 1.3 m / min. Optionally, the casting speed of the high-alloy steel billet 6 is 0.8 m / min to 1.2 m / min, and can be stabilized at a fixed casting speed according to production conditions. It should be noted that the casting speed refers to the speed at which the continuously cast billet 6 is conveyed between the paired drive rollers 42 and driven rollers 43 after the billet shell is formed in the continuous casting machine. Exemplarily, the casting speed can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.83, 0.85, 0.88, 0.9, 0.93, 0.96, 1.0, 1.2, or 1.28 m / min.

[0038] In some embodiments, weak cooling is selected during the secondary cooling process of the continuously cast billet 6 to further reduce the cooling intensity of the continuously cast billet 6, increase the temperature of the continuously cast billet 6 in the sector section 4, and reduce the mechanical strength of the continuously cast billet 6.

[0039] Specifically, in some embodiments, the specific water content of the high-alloy steel continuous casting billet 6 at the casting speed is 0.26 L / kg to 0.48 L / kg. Optionally, the specific water content of the high-alloy steel continuous casting billet 6 at the casting speed is 0.29 L / kg to 0.42 L / kg. Exemplarily, the specific water content of the two water-tightening pellets is 0.28, 0.30, 0.32, 0.35, 0.38, 0.40, 0.42, 0.45, and 0.47 L / kg.

[0040] The method for producing high-alloy steel by continuous casting according to the embodiments of this application reduces the specific water content of the high-alloy steel continuous casting billet 6 at various casting speeds during the production of the continuous casting billet 6. During the secondary cooling process of the continuous casting billet 6, a weak cooling mode that meets the above specific water content is selected, thereby reducing the cooling intensity of the continuous casting billet 6, increasing the temperature of the continuous casting billet 6 in the sector section 4, and reducing the mechanical strength of the continuous casting billet 6. This reduces the interaction between the drive roller 42 and the continuous casting billet 6, thus extending the service life of the sector section 4 of the continuous casting machine.

[0041] In some embodiments, the casting speed and specific water content of the high-alloy steel continuously cast billet 6 during the production process satisfy the corresponding relationship shown in Table 2 below. It should be noted that different casting speeds result in different specific water contents. To prevent the continuously cast billet 6 from bulging, a higher casting speed corresponds to a larger specific water content. Furthermore, the casting speeds in Table 2 represent specific water contents applicable to that value and its corresponding casting speed range.

[0042] Table 2 Comparison of specific water volume

[0043] Pulling speed / m / min 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 Original water volume / L / Kg steel 0.43 0.47 0.53 0.57 0.6 0.64 0.67 0.71 0.73 This application specifies the water content (L / Kg steel) 0.26 0.29 0.32 0.36 0.38 0.41 0.44 0.46 0.48

[0044] like Figure 3 and Figure 4As shown, the sector section 4 is an important component of the slab continuous casting machine. Its functions include receiving the continuously cast slab 6 initially formed from the crystallizer 5 and forcibly cooling the slab 6 by spraying water or using air mist to increase the shell thickness of the slab 6 and avoid "bulging" or steel leakage accidents caused by the static pressure of molten steel. As shown in Table 2, after the continuously cast slab 6 has a shell, it needs to be continuously sprayed with water or air-water mist cooling with a corresponding specific water volume to continue the spray cooling of the slab 6 until the slab 6 is completely solidified. Using the specific water volume corresponding to the above casting speed for cooling can reduce the large changes in the strength of the slab 6 during the cooling and solidification process of the sector section 4, prevent the mechanical strength of the slab 6 from increasing significantly, thereby reducing the interaction between the drive roller 42 and the driven roller 43 and the slab 6, so that the service life of the sector section 4 of the continuous casting machine can be effectively extended.

[0045] The sector section 4 of the continuous casting machine serves to support and guide the continuously cast billet 6. It is the equipment that directly contacts the billet 6 during its solidification process, significantly influencing both its surface and internal quality. The primary purpose of controlling the sector section 4 is to ensure accurate and stable control of the drive roller 42 and the roll gap d of the driven roller 43 according to process requirements. Figure 5 As shown, the sector section 4 of the continuous casting machine includes two rows of rollers, namely inner arc rollers and outer arc rollers. Generally, the inner arc roller and outer arc roller in the middle of each sector section 4 are used as drive rollers 42 and are arranged in groups. The gap formed between the driven rollers 43 arranged in groups of outer arc rollers and inner arc rollers is the roller gap d of the driven rollers 43 of the sector section 4. The continuously cast billet 6, which has initially solidified in the continuous casting crystallizer 5, passes through the roller gap d of the sector section 4, which further stabilizes the shape of the billet. The thickness of the continuously cast billet is the size of the roller gap d of the sector section 4 through which it passes.

[0046] In the production of ordinary steel, the roll gap d of the sector segment 4 generally adopts a contracted roll gap d. The contracted roll gap d means that the roll gap d at the inlet 40a of the sector segment 4 is smaller than the roll gap d at the outlet 40b of the sector segment 4, typically by 0.1mm to 0.4mm. The method for continuous casting production of high-alloy steel provided in this application reduces the total reduction of the driven roller 43 by adjusting the roll gap d of the driven roller 43 in the sector segment 4 after the light pressing section from the original contracted roll gap to a parallel roll gap or an open roll gap, while maintaining the reduction of the light pressing section unchanged. The total reduction is the value of the roll gap d of the driven roller 43 at the inlet 40a of the sector segment 4 minus the roll gap d of the driven roller 43 at the outlet 40b of the sector segment 4.

[0047] In some embodiments, as shown in Tables 3 and 5, in the step of adjusting the roll gap d of the driven roller 43 in the fan-shaped section 4 after the light pressing from the original shrinking roll gap to a parallel roll gap or an open roll gap to reduce the total pressing amount of the driven roller 43 in the fan-shaped section 4, the total pressing amount of the driven roller 43 is reduced from 11 mm to 6.8 mm to 8.8 mm, and the total pressing amount is reduced by 4.2 mm to 2.2 mm, but the pressing amount of the light pressing section remains unchanged.

[0048] In the method for continuous casting of high-alloy steel provided in this application embodiment, parallel roll gap refers to the roll gap d at the inlet 40a of the sector segment 4 being equal to the roll gap d at the outlet 40b of the sector segment 4. Open roll gap refers to the roll gap d at the inlet 40a of the sector segment 4 being greater than the roll gap d at the outlet 40b of the sector segment 4, or vice versa. Generally, the roll gap d of the sector segment 4 is manually opened when the large deviation of the roll gap d in the sector segment 4 causes high pressure on the drive roller 42. Each casting speed has a corresponding roll gap d to improve the internal quality of the continuously cast billet 6 and reduce the force required to pull the continuously cast billet 6. It should be noted that open roll gap and parallel roll gap can be used individually or simultaneously. Simultaneous use means using parallel roll gap in some areas of the sector segment and open roll gap in others.

[0049] The method for continuous casting of high alloy steel in this application embodiment prevents the roll gap deviation (i.e., equipment accuracy) of the fan-shaped section 4 after light pressing from causing high pressure in the fan-shaped section 4. Based on this, the pressure of the light pressing section in the method for continuous casting of high alloy steel in this application is adjusted to below 160 Bar.

[0050] Table 3. Roll gap table for each speed range

[0051] Roller gap table Original roll gap speed range This application adjusts the roll gap speed range. 2 0.3 0.44 3 [0.30-0.44) [0.44-0.58) 4 [0.44-0.58) [0.58-0.71) 5 [0.58-0.71) [0.71-0.83) 6 [0.71-0.83) [0.83-0.93) 7 [0.83-0.93) [0.93-1.03) 8 [0.93-1.03) [1.03-1.13) 9 [1.03-1.13) [1.13-1.27) 10 [1.13-1.27) [1.27-1.39) 11 [1.27-1.39) [1.39-1.50) 12 1.39 ≥1.50

[0052] Note: The continuous casting speed range refers to the speed range at which the continuously cast billet 6 is pulled out of the crystallizer 5 during the continuous casting process. The casting speed is usually expressed as the length of the continuously cast billet 6 pulled out per minute (meters / minute). It should be noted that if the correspondence between casting speed and roll gap is not adopted, the internal quality of the continuously cast billet 6 will be correspondingly worse, making it difficult to meet the quality requirements of the continuously cast billet 6.

[0053]

[0054]

[0055] Note: In Tables 4 and 5, Vc represents the casting speed of the continuous casting billet 6. "Tables 2, 4..." indicates that the continuous casting billet 6 is produced using the roll gap d parameter in the corresponding group of the table at the corresponding casting speed. In Table 4, "Seg.1, Seg.2..." represents the roll gap d parameter between each group of adjacent driven rolls 43 from the inlet 40a to the outlet 40b in Tables 2 and 4. Inlet represents the roll gap d parameter entering the roll gap d, and Outlet represents the roll gap d parameter exiting the roll gap d.

[0056] In improving the existing continuous casting process, the inventors discovered that the first and second hydraulic cylinders in the sector section 4 of the continuous casting machine primarily function as clamping and supporting cylinders. The first hydraulic cylinder drives the connected frame 41 to adjust the position of the frame 41 and the driven rollers 43 mounted on it, thereby adjusting the roll gap d between the driven rollers 43 to clamp and support the continuously cast billet 6. The sector section 4 typically includes multiple pairs of driven rollers 43 and a pair of drive rollers 42. It should be noted that the drive rollers 42 are driven by the second hydraulic cylinder, allowing for displacement and pressure control to ensure stable positioning. The first hydraulic cylinder of the sector section 4 clamps the workpiece, enabling machining and inspection. It has a large clamping force and good clamping effect, and can clamp workpieces of various shapes. The drive rollers 42, driven by the second hydraulic cylinder, can be positioned stably through displacement control, preventing billet deformation and dummy bar deviation.

[0057] It should be noted that the sector segment includes drive rollers and driven rollers, and the roll gaps between the grouped drive rollers and grouped driven rollers are equal or have an error of ≤2%. That is, the roll gaps of the drive rollers and driven rollers processing the continuous casting billet are basically consistent, so as to provide stable conveying and support for the continuous casting billet.

[0058] Due to inherent errors in the curvature of the sector segment 4, and the precision errors in the continuous casting billet 6 after it is placed into the drive roller 42 and driven roller 43, the drive roller 42 experiences significant stress. Consequently, the second hydraulic cylinders driving and controlling the drive roller 42 require higher pressure to achieve the desired driving and control. A typical sector segment 4 has six hydraulic cylinders. One first hydraulic cylinder is located at the inlet 40a on both the left and right sides along the width direction, and another first hydraulic cylinder is located at the outlet 40b on both the left and right sides along the width direction. These cylinders control the lifting and lowering of the frame 41, thereby controlling the roll gap d. The two second hydraulic cylinders, connected to the two ends of the drive roller 42, apply positive pressure to the continuous casting billet 6 and rotate it, thus propelling the billet 6 forward. By altering the pressure of the first hydraulic cylinders at the inlet 40a and outlet 40b of the sector segment 4, the problem of high pressure in the first hydraulic cylinders of the sector segment 4 and high resistance to billet pulling caused by roll gap d deviation can be reduced.

[0059] The method for continuous casting of high-alloy steel provided in this application embodiment, as shown in Table 7, involves adjusting the maximum pressure of the first hydraulic cylinder in the sector section 4 following the light pressing section from 200 bar to below 160 bar, optionally to 60 bar to 160 bar, or 60 bar to 100 bar, or 120 bar to 160 bar, optionally adjusting to any value within the above range. For example, optionally adjusting to 120 bar reduces the effect of the driven roller 42 on the continuously cast billet 6, preventing the problem of high pressure in the sector section 4 due to equipment precision deviation. This significantly reduces the pressure of the first hydraulic cylinder in the sector section 4 following the light pressing section, lowering the average pressure from 132 bar to 65 bar. For example, the pressure of the first cylinder can be 68, 70, 72, 75, 80, 83, 85, 90, 92, 95, 100, 104, 108, 110, 116, 120, 125, 130, 135, 140, 145, 150, 155, or 158 bar.

[0060] The method for producing high alloy steel by continuous casting provided in this application further reduces the effect of the drive roller 42 on the continuous casting billet 6 by adjusting the maximum pressure of the first oil cylinder in the sector section 4 after the light pressing section from 200 bar to 120 bar. This prevents the problem of high pressure in the first oil cylinder 410 of the sector section 4 and high resistance to pulling the continuous casting billet 6 due to equipment precision deviation, and further improves the precision of the sector section of the continuous casting machine to prevent damage to the continuous casting machine.

[0061] Table 6 Pressure gauges for the first cylinder in the sector segment before improvement.

[0062]

[0063]

[0064] Table 7 Pressure gauge of the first cylinder in the improved sector segment

[0065]

[0066] Note: In Tables 6 and 7, “sector 1#, sector 2#, ..., sector 13#” refer to the pressure of the driven rollers of the first group, the second group, ..., the 13th group in the sector segment, respectively.

[0067] The technical effects of the method for continuous casting production of high alloy steel provided in this application are verified below through specific embodiments and comparative examples.

[0068] Example 1

[0069] This application employs a method for the continuous casting production of high-alloy steel, wherein the high-alloy steel is C20MN23ALV (C content 0.2%, Mn content 23.0%, Al content 2.0%, V content 0.1%). The method includes: during the production of the continuously cast billet 6, the casting speed of the billet 6 in the sector section 4 is set to 0.8 m / min to 0.9 m / min, reducing the specific water content of the high-alloy steel billet 6 at this casting speed to 0.36 L / kg to 0.38 L / kg steel, thereby improving the continuous casting efficiency. The temperature of billet 6 within sector 4; the roll gap d of driven roller 43 in sector 4 after the light pressing section is changed from a contraction roll gap to a parallel roll gap, and the last two sector sections 4 are opened by 1.0 mm to form an open roll gap, with the roll gap of the last sector section 4 being 240 mm, in order to reduce the total pressing amount of driven roller 43, reducing the total pressing amount of driven roller to 6.8 mm, while keeping the pressing amount of the light pressing section unchanged; the maximum pressure of the first oil cylinder 410 in sector 4 after the light pressing section is set to 120 bar to reduce the pressure of continuous casting billet 6 on sector 4.

[0070] The method for continuous casting of high-alloy steel used in Example 1 achieves outstanding technical effects in the following aspects:

[0071] 1. Reduce the pressure of the hydraulic cylinder. After lightly pressing down, the average pressure of the first hydraulic cylinder 410 of the sector segment 4 drops to 78 bar; reduce the average torque of the drive roller 42. The average torque of the drive roller 42 drops from 6360 N·m to 2375 N·m.

[0072] 2. Reduce the occurrence rate of continuous casting billet 6 not being able to be pulled, with the occurrence rate of continuous casting billet 6 not being able to be pulled as low as 0 times / furnace.

[0073] 3. Improve the average replacement life of sector section 4, increasing the average replacement cycle of sector section 4 to 6800 furnaces.

[0074] Example 2

[0075] This application employs a method for the continuous casting production of high-alloy steel, wherein the high-alloy steel is C0.4Cr13 (C content 0.4%, Cr content 13.0%). The method includes: during the production of the continuously cast billet 6, the casting speed of the billet 6 in the sector section 4 is set to 1.0 m / min to 1.2 m / min, reducing the specific water content of the high-alloy steel billet 6 at this casting speed to 0.41 L / kg to 0.46 L / kg steel, thereby improving... The temperature of the continuously cast billet 6 within the sector section 4; the roll gap d of the driven roller 43 in the sector section 4 following the light pressing section is changed from a shrinking roll gap to a parallel roll gap, and the roll gap of the last sector section 4 is 238mm, in order to reduce the total pressing amount of the driven roller 43, the total pressing amount of the driven roller is reduced to 8.8mm, and the pressing amount of the light pressing section remains unchanged; the maximum pressure of the first oil cylinder 410 in the sector section 4 following the light pressing section is set to 160bar, in order to reduce the pressure of the continuously cast billet 6 on the sector section 4.

[0076] The method for continuous casting of high-alloy steel used in Example 2 achieves outstanding technical effects in the following aspects:

[0077] 1. Reduce the pressure of the hydraulic cylinder. After lightly pressing down, the average pressure of the first hydraulic cylinder 410 of the sector section 4 drops to 69 bar; reduce the torque of the drive roller 42. The average torque of the drive roller 42 drops from 5525 N·m to 2070 N·m.

[0078] 2. Reduce the occurrence rate of continuous casting billet not being able to be pulled out, with the occurrence rate of billet not being able to be pulled out as low as 0 times / furnace.

[0079] 3. Improve the average replacement life of sector section 4, with an average replacement cycle of up to 7100 furnaces.

[0080] Example 3

[0081] This application employs a method for the continuous casting production of high-alloy steel, wherein the high-alloy steel is C1MN13CR2 (C content 1.0%, MN content 13%, Cr content 2.0%). The method includes: during the production of the continuously cast billet 6, the casting speed of the continuously cast billet 6 in the sector section 4 is set to 0.8 m / min to 1.2 m / min, reducing the specific water content of the high-alloy steel continuously cast billet 6 at the casting speed to 0.32 L / kg steel, thereby increasing the temperature of the continuously cast billet 6 within the sector section 4. The roll gap d of the driven roller 43 in the sector section 4 following the light pressing section is changed from a shrinking roll gap to a parallel roll gap, and the last sector section 4 is opened by 1.0 mm to an open roll gap d, with the roll gap of the last sector section 4 being 239 mm, in order to reduce the total pressing amount of the driven roller 43, reducing the total pressing amount of the driven roller to 7.8 mm, while keeping the pressing amount of the light pressing section unchanged; the maximum pressure of the first oil cylinder 410 in the sector section 4 following the light pressing section is set to 120 bar, in order to reduce the pressure of the continuous casting billet 6 on the sector section 4.

[0082] The method for continuous casting production of high-alloy steel used in Example 3 achieves outstanding technical effects in the following aspects:

[0083] 1. Reduce the pressure of the hydraulic cylinder. After lightly pressing down, the average pressure of the first hydraulic cylinder 410 of the sector section 4 drops to 72 bar; reduce the torque of the drive roller 42. The average torque of the drive roller 42 drops from 5830 N·m to 2175 N·m.

[0084] 2. Reduce the occurrence rate of continuous casting billet not being able to be pulled out, with the occurrence rate of billet not being able to be pulled out as low as 0 times / furnace.

[0085] 3. Improve the average replacement life of sector section 4, with an average replacement cycle of up to 7260 furnaces.

[0086] Example 4

[0087] This application employs a method for the continuous casting production of high-alloy steel, wherein the high-alloy steel is 5MN24 (C content 0.5%, Mn content 24%). The method includes: during the production of the continuously cast billet 6, the casting speed of the billet 6 in the sector section 4 is set to 0.9 m / min to 1.1 m / min, reducing the specific water content of the high-alloy steel billet 6 at the casting speed to 0.38 L / kg to 0.44 L / kg steel, thereby improving the continuous casting billet... 6. Temperature within sector 4; The roll gap d of driven roller 43 in sector 4 after the light pressing section is changed from a shrinking roll gap to a parallel roll gap, and the roll gap of the last sector 4 is 238mm, in order to reduce the total pressing amount of driven roller 43, the total pressing amount of driven roller is reduced to 8.8mm, and the pressing amount of the light pressing section remains unchanged; The maximum pressure of the first oil cylinder 410 in sector 4 after the light pressing section is set to 120bar, in order to reduce the pressure of continuous casting billet 6 on sector 4.

[0088] The method for continuous casting of high-alloy steel used in Example 4 achieves outstanding technical effects in the following aspects:

[0089] 1. Reduce the pressure of the hydraulic cylinder. After lightly pressing down, the average pressure of the first hydraulic cylinder 410 of the sector section 4 drops to 76 bar; reduce the torque of the drive roller 42. The average torque of the drive roller 42 drops from 5250 N·m to 1975 N·m.

[0090] 2. Reduce the occurrence rate of continuous casting billet not being able to be pulled out, with the occurrence rate of billet not being able to be pulled out as low as 0 times / furnace.

[0091] 3. Improve the average replacement life of sector section 4, with an average replacement cycle of up to 7300 furnaces.

[0092] Comparative Example 1

[0093] The only difference from Example 1 is the change in pulling speed; all other parameters remain unchanged. Specifically, setting the pulling speed to 0.5 m / min results in poorer technical performance in the following aspects:

[0094] 1. The pressure of the first cylinder 410 is 158 bar, and the average torque of the drive roller 42 is 6360 N·m, which is much higher than 2875 N·m in Example 1.

[0095] 2. The occurrence rate of the billet being unable to be pulled is 0.2 times / furnace.

[0096] 3. Increase the average replacement life of sector 4 to 1613 furnaces.

[0097] Comparative Example 2

[0098] The only difference from Example 1 is the change in pulling speed; all other parameters remain unchanged. Specifically, setting the pulling speed to 1.4 m / min results in poorer technical performance in the following aspects:

[0099] 1. The pressure of the first cylinder 410 is 125 bar, and the average torque of the drive roller 42 is 5525 N·m, which is much higher than 2670 N·m in Example 1.

[0100] 2. The occurrence rate of the billet being unable to be pulled is 0.16 times / furnace.

[0101] 3. The average replacement life of sector 4 is 2937 furnaces.

[0102] Comparative Example 3

[0103] The only difference from Example 1 is that the reduction amount of the fan-shaped segment 4 following the light reduction section is changed, while all other parameters remain unchanged. The roll gap d of the fan-shaped segment 4 following the light reduction section is still changed from a shrinking roll gap to a parallel roll gap, but the total reduction amount is reduced to 9.3 mm. The shrinkage of the roll gap d of the fan-shaped segment 4 before the light reduction section has a smaller impact, while the impact of the fan-shaped segment 4 after the light reduction section is larger. The corresponding technical effects are poor in the following aspects:

[0104] 1. The pressure of the first hydraulic cylinder 410 is 116 bar, which is much higher than the 78 bar in Example 1; the torque of the drive roller 42 is 5845 N·m.

[0105] 2. The occurrence rate of the continuously cast billet 6 being unable to be pulled is as high as 0.083 times / furnace.

[0106] 3. The average replacement life of sector 4 is 3500 furnaces.

[0107] Comparative Example 4

[0108] The only difference from Example 1 is that the maximum pressure of the first cylinder 410 of the fan-shaped section 4 after the light pressure section is changed from 120 bar in Example 1 to 180 bar, while other parameters remain unchanged.

[0109] The technical performance is poor in the following aspects:

[0110] 1. The pressure of the first hydraulic cylinder 410 is 126 bar, which is much higher than the 78 bar in Example 1; the average torque of the drive roller 42 is 826 N·m.

[0111] 2. The occurrence rate of the billet being unable to be pulled is 0.10 times / furnace.

[0112] 3. The average replacement life of sector section 4, that is, the average replacement cycle of sector section 4 is 2760 furnaces.

[0113] Comparative Example 5

[0114] The only difference from Example 1 is the change in specific water content, while other parameters remain unchanged. Specifically, setting the specific water content to 0.68 L / kg steel results in poorer technical performance in the following aspects:

[0115] 1. The pressure of the first hydraulic cylinder 410 is 119 bar, which is much higher than the 78 bar in Example 1; the average torque of the drive roller 42 is 4080 N·m.

[0116] 2. The occurrence rate of continuously cast billet 6 being unable to be pulled is 0.15 times / furnace.

[0117] 3. The average replacement life of sector section 4, that is, the average replacement cycle of sector section 4 is 2996 furnaces.

[0118] The comparison results of the above embodiments and comparative examples show that:

[0119] By reducing the specific water content of the high-alloy steel continuous casting billet 6 at various casting speeds during the production process, the cooling rate and intensity of the billet 6 are reduced, the temperature of the billet 6 within the sector section 4 is increased, and the strength of the billet 6 is reduced. Furthermore, by adjusting the correspondence between the casting speed and the roll gap d table, the internal quality of the billet 6 is controlled. This reduces the average torque of the drive roller 42 in the sector section 4 from 5250 N*m to 6360 N*m to 1800 N*m to 2375 N*m. It also solves the problem of the billet 6 being unable to be drawn during the production of high-alloy steel billets 6, reducing the occurrence rate of this problem from 0.083 times / heat of molten steel to 0 times / heat of molten steel. Without affecting the production quality of high alloy steel, these process improvements minimize damage to the sector section of the continuous casting machine, increasing the service life of sector section 4 from 3,500 heats of molten steel to over 6,500 heats of molten steel, and maintaining the service life of sector section 4 at over 95%.

[0120] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for continuously casting high-alloy steel, characterized in that, include: During the continuous casting billet production process, the specific water content of the high alloy steel continuous casting billet is reduced at the casting speed, which is 0.26 L / kg steel to 0.48 L / kg steel. The casting speed of the high alloy steel continuous casting billet is 0.5 m / min to 1.3 m / min. During the secondary cooling process of the continuous casting billet, weak cooling is selected to reduce the cooling intensity of the continuous casting billet and increase the temperature of the continuous casting billet in the sector section. The roll gap of the driven roller in the sector section following the light pressing section is set to a parallel roll gap or an open roll gap to reduce the total pressing amount of the driven roller while keeping the pressing amount of the light pressing section unchanged. A first hydraulic cylinder is installed on each of the left and right sides along the width direction at the inlet of the sector section, and a first hydraulic cylinder is installed on each of the left and right sides along the width direction at the outlet of the sector section; the maximum pressure of the first hydraulic cylinder in the sector section after the light pressure section is set to below 160 bar to reduce the pressure of the continuously cast billet on the sector section.

2. The method for continuous casting production of high-alloy steel according to claim 1, characterized in that, During the continuous casting billet production process, the casting speed of the high alloy steel billet is 0.8m / min to 1.2m / min.

3. The method for continuous casting production of high-alloy steel according to claim 1, characterized in that, The specific water content of the high alloy steel continuous casting billet at the casting speed is 0.29 L / kg steel to 0.46 L / kg steel.

4. The method for continuous casting production of high-alloy steel according to claim 1, characterized in that, The casting speed and specific water content of the high alloy steel billet meet the following corresponding relationships: 0.5m / min-0.26L / kg steel, 0.6m / min-0.29L / kg steel, 0.7m / min-0.32L / kg steel, 0.8m / min-0.36L / kg steel, 0.9m / min-0.38L / kg steel, 1.0m / min-0.41L / kg steel, 1.1m / min-0.44L / kg steel, 1.2m / min-0.46L / kg steel, and 1.3m / min-0.48L / kg steel.

5. The method for continuous casting production of high-alloy steel according to claim 1, characterized in that, In the step of setting the roll gap of the driven roller in the sector section after the light pressing section to a parallel roll gap or an open roll gap in order to reduce the total pressing amount of the driven roller in the sector section, the total pressing amount of the driven roller is reduced to 6.8mm to 8.8mm, the total pressing amount is reduced by 4.2mm to 2.2mm, and the pressing amount of the light pressing section remains unchanged.

6. The method for continuous casting production of high-alloy steel according to claim 1, characterized in that, The maximum pressure of the first cylinder in the fan-shaped section following the light pressure section is set to 60 bar to 160 bar.

7. The method for continuous casting production of high-alloy steel according to claim 6, characterized in that, The maximum pressure of the first cylinder in the fan-shaped section following the light pressure section is set to 60 bar to 100 bar or 120 bar to 160 bar.

8. The method for continuous casting production of high-alloy steel according to claim 1, characterized in that, The sector segment includes a drive roller and a driven roller. The roll gap between the grouped drive rollers and the grouped driven rollers is equal, or the error of the roll gap between the grouped drive rollers and the grouped driven rollers is ≤2%.

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