Control methods for high carbon and high manganese steel and its continuous casting shutdown

Abstract

This invention provides a method for controlling the shutdown of high-carbon, high-manganese steel in continuous casting, comprising: before shutdown, reducing the casting speed to a first target casting speed; after stabilization, removing the protective slag from the crystallizer, closing the stopper rod and setting a blind plate; simultaneously reducing the flow rate of the cooling water on the wide face of the crystallizer from the first target flow rate to the second target flow rate; switching the secondary cooling water system before the straightening section to a semi-automatic locked flow rate mode, switching the first target casting speed to the second target casting speed, activating the tail billet mode and deactivating the light pressing function; after removing the submerged entry nozzle, adding cooling components into the crystallizer, and continuously pulling out the tail billet at a third target casting speed; after the tail billet has completely detached from the crystallizer, running at a fourth target casting speed for 2-4 minutes; and then pulling out the tail billet from the fan-shaped section at a fifth target casting speed; the first target flow rate is 5100-6100 L / min; the second target flow rate is 4000-4500 L / min. The process is simple and easy to operate.

Description

Technical Field

[0001] This invention belongs to the field of continuous casting technology for steel, and particularly relates to a method for controlling the shutdown of continuous casting of high-carbon, high-manganese steel. Background Technology

[0002] High-carbon, high-manganese steel is a special type of high-strength alloy steel, typically containing more than 1.0% carbon and more than 10% manganese. This composition gives it excellent wear resistance, enabling it to exhibit good wear resistance under high stress and high impact conditions, thus meeting the design and construction requirements of structural materials in various fields.

[0003] However, the extremely high carbon and manganese content in high-carbon, high-manganese steel presents numerous technical challenges in its production, especially during continuous casting. The poor fluidity of molten high-carbon, high-manganese steel increases the difficulty during the pouring and tail-out stages. Direct tail-out during the continuous casting shutdown stage easily leads to overflow, making it difficult to pull the slab, causing deviations in casting machine precision and low production efficiency. Currently, some steel mills use mixed pouring or tail-out water injection during the tail-out shutdown stage, but the composition of the slab produced by mixed pouring does not meet the requirements of any single steel grade, rendering the mixed slab unusable and resulting in wasted production costs. Tail-out water injection is complex to operate and its effectiveness is unstable. Therefore, this invention provides a method for controlling the continuous casting shutdown of high-carbon, high-manganese steel. Summary of the Invention

[0004] The main objective of this invention is to provide a method for controlling the shutdown of high-carbon, high-manganese steel in continuous casting, aiming to solve the technical problems of easy expansion and low production efficiency caused by direct tail discharge during shutdown of high-carbon, high-manganese steel continuous casting in the prior art.

[0005] To achieve the above objectives, the present invention provides a method for controlling the shutdown of continuous casting of high-carbon, high-manganese steel, comprising the following steps:

[0006] Before stopping casting, reduce the casting speed to the first target casting speed. After stabilizing, remove the protective slag from the crystallizer, close the stopper rod and install the blind plate. Simultaneously, reduce the cooling water flow rate of the wide face of the crystallizer from the first target flow rate to the second target flow rate.

[0007] Switch the secondary cooling water system before the straightening section to semi-automatic locked flow mode to maintain the second target flow rate of cooling water, switch the first target pulling speed to the second target pulling speed, enable the tail billet mode and deactivate the light pressing function.

[0008] After removing the immersion nozzle, a cooling element is added into the crystallizer, and the tail billet is continuously pulled out at the third target pulling speed.

[0009] After the billet has completely detached from the crystallizer, run it at the fourth target pulling speed for 2-4 minutes; then pull the billet out of the fan-shaped section at the fifth target pulling speed.

[0010] The first target flow rate is 5100~6100 L / min; the second target flow rate is 4000~4500 L / min.

[0011] The fifth target pulling speed > the fourth target pulling speed > the first target pulling speed ≥ the second target pulling speed ≥ the third target pulling speed.

[0012] According to the embodiments of this application, the first target pulling speed is 0.6~0.9 m / min; the second target pulling speed is 0.4~0.6 m / min; the third target pulling speed is 0.2~0.4 m / min; the fourth target pulling speed is 0.9~1.1 m / min; and the fifth target pulling speed is 1.2~2.0 m / min.

[0013] According to the implementation method of this application, if molten steel swells after the tail billet completely leaves the crystallizer, the tail billet is directly pulled out of the fan-shaped section at the fifth target pulling speed, and no shutdown operation is performed.

[0014] According to the embodiments of this application, the cooling element is a rigid structure welded from cooling steel plates or flat steel.

[0015] According to the embodiments of this application, in the step of adding a cooling element into the crystallizer after removing the immersion nozzle, a cooling spring and / or iron filings are selectively added according to the solidification state of the tail billet.

[0016] According to the embodiments of this application, the method for controlling the shutdown of continuous casting of high carbon and high manganese steel further includes inspecting the continuous casting machine after the tail billet is pulled out of the fan-shaped section to ensure that the accuracy of the continuous casting machine meets the standard.

[0017] According to an embodiment of this application, the first target flow rate is reduced to the second target flow rate at a rate of 50~100 L / min·s.

[0018] The present invention also provides a high-carbon high-manganese steel prepared by the above-described control method, wherein the components of the high-carbon high-manganese steel, by mass percentage, include: C 0.90~1.40%, Mn 11.0~14.0%, Si 0.30~0.70%, P≤0.035%, S≤0.020%, Al 0.015~0.10%, with the balance being Fe and unavoidable impurities.

[0019] According to the embodiments of this application, the high-carbon high-manganese steel has a yield strength of 400~500MPa, a tensile strength of 900~1000MPa, and an elongation of ≥15%.

[0020] According to the embodiments of this application, the coefficient of linear expansion of the high-carbon high-manganese steel at high temperatures is 1.5 to 2.0 times that of ordinary steel.

[0021] The surface hardness after work hardening is HB550 or higher.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention provides a method for controlling the shutdown of high-carbon, high-manganese steel in continuous casting. Before shutdown, the casting speed is reduced to a first target speed, and after stabilization, the protective slag inside the mold is removed, ensuring good lubrication between the inner wall of the mold and the billet. This avoids mold adhesion and billet surface defects caused by residual protective slag, improving the service life of the mold and the surface quality of the billet. By adjusting the casting speed and cooling water flow rate in stages, the continuous casting process is made smoother, reducing fluctuations caused by sudden parameter changes and improving the stability of continuous casting. It also reduces surface cracks and internal defects in the billet caused by fluctuations in cooling water flow rate, helping to ensure billet quality. Activating the tail billet mode and deactivating the light reduction function, as well as removing the submersible nozzle and adding cooling components, allows the tail billet to quickly detach from the fan-shaped section with appropriate casting speed and cooling conditions, improving the efficiency of tail billet processing, reducing the residence time of the tail billet in the fan-shaped section, and lowering the risks during tail billet processing. This invention achieves direct tail-out of high-carbon, high-manganese steel through the coordinated use of parameters and process modes. This avoids damage to the casting machine and its precision, while also preventing the waste slabs generated by mixed casting tail-out. It combines the advantages of both direct and mixed casting tail-out processes while mitigating their respective risks, resulting in significant economic benefits. Furthermore, the control method of this invention is easy to operate, reduces production costs, and is suitable for continuous industrial production. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 This is a process flow diagram of the method for controlling the shutdown of continuous casting of high-carbon and high-manganese steel according to the present invention.

[0026] Figure 2 The image shows a microscope image of a high-carbon, high-manganese steel according to an embodiment of the present invention; wherein, (a) is magnified 200 times, and (b) is magnified 50 times.

[0027] Figure 3 The diagram shows the internal microstructure of different length regions of the high-carbon, high-manganese steel slab obtained by the control method for stopping continuous casting of high-carbon, high-manganese steel according to the present invention.

[0028] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0031] High-manganese steel refers to high-strength alloy steel with a manganese content of over 10%. Due to the varying manganese content, it possesses material properties different from traditional low-carbon steel, such as work hardening, wear resistance, high toughness, and low-temperature resistance, which can meet the design and construction requirements of structural materials in various fields. However, high-manganese steel presents significant technical challenges. Firstly, with the increase in manganese content, the molten steel exhibits poor fluidity, low thermal conductivity, large linear shrinkage, and a small temperature difference between the solidus and liquidus, making the casting and unloading of high-manganese steel billets more difficult and prone to segregation, cracks, and other internal and external defects. High-carbon high-manganese steel combines the characteristics of both high-carbon and high-manganese steels, exhibiting high strength and hardness. Its mechanical strength at high temperatures is 2 to 3 times that of low-alloy steel or ordinary carbon steel. However, it has poor plasticity at high temperatures, making it prone to surface transverse cracks on slabs after straightening in continuous casting. During solidification, the molten steel undergoes no phase transformation, with grains engulfing and growing, resulting in an inherently coarse-grained steel. Furthermore, its low heat transfer coefficient makes it susceptible to grain boundary cracking and development into severe internal cracks during continuous casting with rapid cooling. Its large coefficient of volume shrinkage also leads to premature formation of large air gaps in the crystallizer, potentially causing steel leakage accidents.

[0032] Because of the high carbon content in high-carbon and high-manganese steel, a large amount of carbide precipitation will occur during solidification. Continuous casting production of large sections is prone to defects such as central segregation, central porosity, and central shrinkage cavities. These characteristics of the solidification process of high-carbon and high-manganese steel bring great difficulties to continuous casting production, especially in the tail-out stopping stage. Some steel plants adopt the mixed casting tail-out method, while others adopt the tail-out water spraying method.

[0033] Due to the aforementioned characteristics of high-carbon and high-manganese steel, it exhibits poor castability during continuous casting. At the tail end, due to its small linear shrinkage, proper tail-end sealing is often difficult, and direct tail-end exit can easily lead to expansion issues. Furthermore, the long draw time at the tail end results in a prolonged residence time of the slab within the fan-shaped section, leading to rapid cooling and a rapid decrease in surface temperature (even lower at the tail end due to its inherent characteristics). This increases the slab strength, requiring the fan-shaped section to withstand greater forces to resist slab deformation. Consequently, the torque of the drive rollers in the fan-shaped section increases sharply during the tail-end stage, causing the slab to become unable to be pulled or to slip. In severe cases, this can lead to roller breakage and water leakage in the fan-shaped section, increased fan-shaped section opening, deviations in casting machine accuracy, increased casting machine inspection and maintenance time, and reduced production efficiency.

[0034] While the mixed casting and tail-out method (in the last heat of the high-manganese steel casting cycle, other steel grades are appropriately arranged to be cast in that cycle; after the high-manganese steel heat is finished and the tundish tonnage reaches a lower level, the heat of the other steel grade is opened for mixed casting in the tundish, and then casting is completed according to the requirements of that steel grade until tail-out) avoids the damage to the casting machine caused by direct tail-out of high-carbon high-manganese steel, the slab composition produced by the mixed casting of the two steel grades does not meet the composition system of either steel grade. The mixed cast slab is unusable and can only be scrapped, resulting in wasted production costs. In addition, the temperature change in the crystallizer is drastic during the mixed casting stage, and adhesion alarms occur frequently, which can easily lead to steel leakage accidents. Therefore, this invention provides a control method for the shutdown of high-carbon high-manganese steel continuous casting, aiming to solve the technical problems of easy expansion and low production efficiency caused by direct tail-out of high-carbon high-manganese steel continuous casting during shutdown.

[0035] To achieve the above objectives, the present invention provides a method for controlling the shutdown of continuous casting of high-carbon, high-manganese steel, comprising the following steps:

[0036] S1: Before stopping casting, reduce the casting speed to the first target casting speed. After stabilization, remove the protective slag in the crystallizer, close the stopper rod and set the blind plate. Simultaneously reduce the flow rate of the cooling water on the wide side of the crystallizer from the first target flow rate to the second target flow rate. The first target flow rate is 5100~6100 L / min; the second target flow rate is 4000~4500 L / min.

[0037] In some embodiments, reducing the casting speed to a first target speed before stopping casting can make the billet more uniformly stressed during solidification. The compositional characteristics of high-carbon, high-manganese steel make it prone to stress concentration during solidification; reducing the casting speed helps slow down stress accumulation inside the billet, thereby reducing the probability of internal cracks. After the first target speed stabilizes, the flow of molten steel in the crystallizer becomes more stable, preventing the protective slag from being drawn into the billet surface during slag removal. Removing the protective slag ensures the cleanliness and smoothness of the billet surface. Closing the stopper and installing a blind flange during casting stoppage prevents unnecessary turbulence in the crystallizer, effectively controlling the flow state of the molten steel and reducing defects such as surface slag entrainment. Simultaneously adjusting the cooling water flow rate across the wide face of the crystallizer from a first target flow rate to a second target flow rate allows for better control of the billet solidification process. High-carbon, high-manganese steel has relatively poor thermal conductivity; by precisely controlling the cooling water flow rate, the solidification rate of the billet during the casting stoppage stage can be regulated, avoiding surface crack defects caused by excessively fast or slow cooling.

[0038] In some embodiments, before stopping the pouring, the pulling speed is reduced and kept stable, so that subsequent operations can be carried out under relatively stable conditions, avoiding operational chaos caused by unstable pulling speed, thereby shortening the time of stopping the pouring.

[0039] In some embodiments, removing the protective slag from the crystallizer before closing the stopper rod avoids safety accidents such as molten steel leakage caused by improper operation sequence. Meanwhile, measures such as installing blind flanges also increase operational safety and reduce the risk of burns from molten steel splashes and high temperatures.

[0040] S2: Switch the secondary cooling water system before the straightening section to semi-automatic locked flow mode to maintain the second target flow of cooling water, switch the first target pulling speed to the second target pulling speed, enable the tail billet mode and deactivate the light pressing function.

[0041] In some embodiments, switching to the semi-automatic locked flow mode enables the secondary cooling water system to cool the billet at a stable flow rate. This avoids uneven surface temperature of the billet caused by fluctuations in cooling water flow, thereby reducing surface crack defects. It also reduces frequent operator intervention in the cooling system, improving operational stability and reliability. Simultaneously, it controls the surface temperature of the billet, reducing surface oxidation caused by localized overheating or insufficient cooling, and helps maintain the cleanliness and smoothness of the billet surface. By switching the casting speed to the second target casting speed, the uniform solidification rate of the billet is improved. A stable casting speed helps reduce the accumulation of internal stress, thereby reducing the risk of internal cracks.

[0042] In some embodiments, during the tail-out stage, due to insufficient molten steel to replenish the cavities created by the solidification and shrinkage of the molten steel, if light pressure is applied to the mushy area at the end of solidification, the molten steel at the end of solidification will flow backward under the pressure of the fan-shaped section. This will damage the already sealed billet shell, causing molten steel to flow out and adhere to the fan-shaped section rollers. Under the action of the straightening machine, this will damage the casting machine equipment. Therefore, activating the tail-out billet mode and deactivating the light pressure function during the tail-out stage can improve the quality of the cast billet, reduce surface and internal defects, reduce equipment wear and malfunctions, thereby reducing scrap rate and equipment maintenance costs.

[0043] In some embodiments, before stopping the pouring, the pulling speed is reduced to 0.8 m / min, and after stabilizing for 1 minute, the slag is scooped out. After the liquid slag is scooped out, the rod is turned off and the blind plate is activated. At the same time, the water flow rate of the wide face of the crystallizer is manually changed from 5100 L / min to 4500 L / min, and the secondary cooling water before the straightening section is semi-automatically locked. The pulling speed is switched to 0.6 m / min and the tail outlet mode is turned off. The light pressing is also canceled.

[0044] S3: After removing the immersion nozzle, add a cooling component into the crystallizer and continue to pull out the tail billet at the third target pulling speed.

[0045] In some embodiments, after removing the submerged entry nozzle, the molten steel flow within the crystallizer is smooth. Adding a cooling element can effectively reduce the temperature within the crystallizer, decreasing the risk of molten steel adhering to the crystallizer wall and effectively preventing steel leakage. The addition of the cooling element can also rapidly reduce the temperature within the crystallizer, allowing the billet surface to solidify quickly and reducing surface cracks caused by excessive temperature.

[0046] In some embodiments, adding a cooling element to the crystallizer can rapidly cool and solidify the surface of the billet, reducing dimensional fluctuations caused by temperature changes, thereby ensuring the size and shape of the tail billet and improving its quality. Continuously pulling out the tail billet at a third target drawing speed reduces the dwell time of the tail billet in the fan-shaped section, shortening the tail billet processing time and thus reducing downtime caused by improper tail billet handling, thereby improving the operating efficiency of the continuous casting machine.

[0047] In some embodiments, after the drain outlet is removed, a cooling component is added (if the cooling component cannot be added, a cooling steel plate is added), and the crystallizer is pulled out at 0.4 m / min. During this process, cooling springs and iron filings are prepared and selectively added depending on the solidification of the tail billet. No stopping operation is allowed during the tailing process.

[0048] S4: After the billet has completely detached from the crystallizer, run at the fourth target pulling speed for 2-4 minutes; then pull the billet out of the fan-shaped segment at the fifth target pulling speed. The fifth target pulling speed > the fourth target pulling speed > the first target pulling speed ≥ the second target pulling speed ≥ the third target pulling speed.

[0049] In some embodiments, after the tail billet has completely detached from the crystallizer, running it at the fourth target casting speed for 2-4 minutes helps reduce the occurrence of cracks and steel leakage caused by excessively high temperatures or insufficient cooling in the fan-shaped section, making the cooling and solidification process of the tail billet in the fan-shaped section more stable. Pulling the tail billet out of the fan-shaped section at the fifth target casting speed reduces the residence time of the tail billet in the fan-shaped section, thereby reducing downtime caused by improper handling of the tail billet and improving the operating efficiency of the continuous casting machine.

[0050] In some embodiments, after the tail billet exits the crystallizer, the casting speed is increased to 0.9 m / min, maintained for 3 minutes, and then increased to 1.5 m / min to pull out the fan-shaped section. If expansion is observed after exiting the crystallizer, the billet is directly pulled out of the continuous casting machine at a speed of 1.5 m / min; stopping the casting machine is strictly prohibited. After stopping casting, check the condition of the casting machine to ensure its accuracy.

[0051] In some embodiments, the control method of the present invention is applicable to the field of high-carbon high-manganese steel tailings stopping casting.

[0052] The aforementioned method for controlling the shutdown of high-carbon, high-manganese steel continuous casting involves reducing the casting speed to the first target speed before shutdown, and then removing the protective slag from the mold after stabilization. This ensures good lubrication between the mold inner wall and the billet, preventing mold adhesion and billet surface defects caused by residual protective slag, thus improving the mold's service life and billet surface quality. By adjusting the casting speed and cooling water flow rate in stages, the continuous casting process transitions more smoothly, reducing fluctuations caused by sudden parameter changes and improving the stability of continuous casting. It also reduces surface cracks and internal defects in the billet caused by fluctuations in cooling water flow rate, helping to ensure billet quality. Activating the tail billet mode and disabling the light reduction function, as well as removing the submersible nozzle and adding cooling components, allows the tail billet to quickly detach from the mold at a suitable casting speed and cooling conditions. This improves the efficiency of tail billet handling, reduces the dwell time of the tail billet in the fan-shaped section, and lowers the risks during tail billet handling. This invention achieves direct tailing out of high-carbon, high-manganese steel through the coordinated use of parameters and process modes. This avoids damage to the casting machine and its precision, while also preventing the production of scrap slabs from mixed casting tailing out. It combines the advantages of both direct and mixed casting tailing out while mitigating their respective risks, resulting in better economic benefits. Furthermore, the continuous casting shutdown control method of this invention enables direct tailing out of high-carbon, high-manganese steel, without affecting the casting machine's condition or causing scrap slabs from mixed casting tailing out. It combines the advantages of both tailing out methods while mitigating their respective risks, resulting in better economic benefits. The control method of this invention is easy to operate, reduces production costs, and is suitable for industrial continuous production.

[0053] In some embodiments, the first target pulling speed is 0.6~0.9 m / min; the second target pulling speed is 0.4~0.6 m / min; the third target pulling speed is 0.2~0.4 m / min; the fourth target pulling speed is 0.9~1.1 m / min; and the fifth target pulling speed is 1.2~2.0 m / min.

[0054] In some embodiments, the first target pulling speed is 0.8 m / min; the second target pulling speed is 0.6 m / min; the third target pulling speed is 0.4 m / min; the fourth target pulling speed is 0.9 m / min; and the fifth target pulling speed is 1.5 m / min.

[0055] In some embodiments, adjusting the first target casting speed before stopping continuous casting can stabilize the formation of the billet and the flow of molten steel in the mold, reduce friction between the billet and the inner wall of the mold, and extend the service life of the mold. Switching to the second target casting speed can shorten the solidification time of the billet and improve the production efficiency of the continuous casting machine. In the tail billet processing stage, reducing the third target casting speed achieves stable cooling and solidification of the tail billet, reducing defects in the tail billet. After the tail billet has completely detached from the mold, running at a fourth target casting speed of 0.9 m / min for 2-4 minutes quickly pulls the tail billet out of the mold, reducing the residence time of the tail billet in the fan section and improving cooling efficiency. It also helps to reduce surface cracks caused by rapid temperature changes in the tail billet in the fan section. Adjusting the fifth target casting speed pulls the tail billet out of the fan section to quickly complete the tail billet processing, reduce friction in the fan section, and extend the service life of the fan section. By reasonably setting the casting speed at different stages, the continuous casting process can be significantly optimized, billet quality and production efficiency can be improved, while reducing equipment wear and failure risks.

[0056] In some embodiments, in step S4, if molten steel surges after the tail billet completely leaves the crystallizer, the tail billet is directly pulled out of the fan-shaped section at the fifth target pulling speed, and no shutdown operation is performed.

[0057] In some embodiments, when molten steel rises in the sector section, the solidification of the molten steel can cause it to stick to the rollers. Directly pulling the tail billet out of the sector section at the fifth target drawing speed can quickly reduce the contact time between the molten steel and the sector section rollers, avoid overflow or other equipment failures caused by molten steel rising, protect the safe operation of the continuous casting equipment, and reduce downtime.

[0058] In some embodiments, the cooling element is a rigid structure welded from cooling steel plates or flat steel.

[0059] In some embodiments, the shape and size of the cooling element are adapted to the crystallizer and the billet to achieve rapid cooling. The cooling steel plate or flat bar has good thermal conductivity and mechanical strength, which can quickly conduct heat from the billet surface to the cooling medium, reducing the residence time of the tail billet in the fan-shaped section, thereby achieving rapid cooling. The uniform cooling process helps to reduce stress concentration inside the tail billet, reduce the risk of internal cracks, and improve the internal quality of the tail billet.

[0060] In some embodiments, in step S3, cooling springs and / or iron filings are selectively added according to the solidification state of the tail billet.

[0061] In some embodiments, cooling springs and / or iron filings are selectively added depending on the solidification of the tail billet, and no interruption operation is allowed during the tailing process. The cooling springs are made of a metal material with high thermal conductivity, such as copper alloy or aluminum alloy. The cooling springs have good thermal conductivity and can quickly transfer heat from the surface of the billet to the cooling medium.

[0062] In some embodiments, to improve cooling efficiency, the cooling spring is adjusted to a spiral shape to increase the contact area with the surface of the billet. By making close contact with the surface of the billet, heat is quickly conducted, accelerating the cooling process of the billet.

[0063] In some embodiments, iron filings possess high specific heat capacity and thermal conductivity, enabling them to absorb and conduct heat. By contacting the surface of the cast billet, the iron filings absorb heat and conduct it to the cooling medium, thereby accelerating the cooling of the billet. Simultaneously, the iron filings can fill the tiny voids on the surface of the billet, reducing heat loss. This results in a more uniform cooling effect and reduces surface cracking caused by uneven cooling.

[0064] In some embodiments, the method for controlling the shutdown of continuous casting of high-carbon and high-manganese steel further includes the step of inspecting the continuous casting machine after the tail billet is pulled out of the fan-shaped section to ensure that the accuracy of the continuous casting machine meets the standard.

[0065] In some embodiments, after the continuous casting of high-carbon, high-manganese steel is stopped, inspecting the continuous casting machine to ensure its accuracy is met is an important follow-up operation. This inspection ensures the accuracy of the equipment's mechanical, electrical, and hydraulic systems, prevents equipment failures, improves billet quality, reduces downtime, increases production efficiency, and optimizes the maintenance and operation efficiency of the continuous casting machine.

[0066] In some embodiments, in step S1, the first target flow rate is reduced to the second target flow rate at a rate of 50~100 L / min·s.

[0067] In some embodiments, adjusting the flow rate at a specific rate ensures smooth flow changes, thereby guaranteeing uniformity in the cooling process of the billet during the shutdown process, reducing the accumulation of thermal stress, and preventing the formation of internal cracks and surface defects.

[0068] The present invention also provides a high-carbon high-manganese steel prepared according to the above-mentioned continuous casting shutdown control method, wherein the high-carbon high-manganese steel comprises, by mass percentage: C 0.90~1.40%, Mn 11.0~14.0%, Si 0.30~0.70%, P≤0.035%, S≤0.020%, Al 0.015~0.10%, with the balance being Fe and unavoidable impurities.

[0069] In some embodiments, carbon can improve the strength and hardness of steel. A carbon content of 0.90–1.40% gives the steel high hardness and wear resistance. Manganese can improve the strength and toughness of steel, while also improving its hardenability. High manganese content significantly improves the strength and toughness of steel. Silicon and aluminum can remove oxygen from steel, improving its purity. Regulating the content of silicon and aluminum helps improve the oxidation resistance of steel.

[0070] The high-carbon, high-manganese steel provided by this invention, through reasonable control of the content of each component and precise regulation of process parameters during the continuous casting shutdown process, results in high-carbon, high-manganese steel with high strength, high toughness, and good wear resistance, and has broad application prospects.

[0071] In some embodiments, the high-carbon high-manganese steel has a yield strength of 400-500 MPa, a tensile strength of 900-1000 MPa, and an elongation of ≥15%.

[0072] In some embodiments, the coefficient of linear expansion of the high-carbon, high-manganese steel at high temperatures is 1.5 to 2.0 times that of ordinary steel.

[0073] The surface hardness after work hardening is HB550 or higher.

[0074] In some embodiments, after work hardening, the surface hardness of high-carbon high-manganese steel is HB550 or higher, and its surface has high wear resistance and scratch resistance, which can extend the service life of the parts. It is suitable for applications such as mining machinery and engineering machinery parts in high-wear environments.

[0075] To further illustrate the present invention, the following examples are provided:

[0076] Example 1

[0077] For the production of high-carbon, high-manganese steel MN13 in February 2025, the operation during the tail-out shutdown process should follow the steps described above. During tail-out, add cooling components, change the water flow rate on the wide face of the crystallizer, cancel the light pressure adjustment, lock the secondary cooling water, and pull the crystallizer out at the specified speed. Specifically, before stopping production, reduce the pulling speed to 0.8 m / min, stabilize for 1 minute, then skim off the slag. After cleaning the liquid slag, close the bar and activate the blind plate. Simultaneously, manually change the water flow rate on the wide face of the crystallizer from 5100 L / min to 4500 L / min. Activate the semi-automatic water lock on the secondary cooling water before the straightening section. Reduce the pulling speed to 0.6 m / min and switch to tail-out mode, canceling the light pressure adjustment. After removing the immersion nozzle, add cooling components and pull the crystallizer out at 0.4 m / min. During this process, prepare cooling springs and iron filings, adding them selectively depending on the solidification of the tail billet. No stopping operations are allowed during the tail-out process. After the billet exits the crystallizer, the drawing speed is increased to 0.9 m / min and maintained for 3 minutes, then increased to 1.5 m / min to draw out the fan-shaped section. From the solidification and shrinkage of the billet inside the crystallizer, no abnormalities were observed. It was able to solidify completely before exiting the crystallizer, and there was no case of billet overflow or incomplete solidification. The billet exit situation was under control.

[0078] in, Figure 1 This is a process flow diagram of the method for controlling the shutdown of continuous casting of high-carbon and high-manganese steel according to the present invention. Figure 2 This is a microscope image of high-carbon, high-manganese steel according to an embodiment of the present invention, wherein, Figure 2 (a) is magnified 200 times. Figure 2 (b) is magnified 50 times; Figure 3 The diagram shows the internal microstructure of different length regions of the high-carbon, high-manganese steel slab obtained by the control method for stopping continuous casting of high-carbon, high-manganese steel according to the present invention.

[0079] Combination Figure 2 It can be seen that the internal structure of high-carbon, high-manganese steel is uniform and free of cracks. From Figure 3It is known that during continuous casting, the solidification structure of the billet is typically divided into equiaxed grain region, mixed grain region, columnar grain region, and surface fine grain region. The equiaxed grain region is located in the center of the billet. The grains in this region are equiaxed, and the cooling rate of the molten steel is relatively slow, allowing sufficient time for the grains to grow freely, resulting in relatively coarse grains. The mixed grain region lies between the equiaxed and columnar grain regions. It contains a mixed structure of equiaxed and columnar grains. The formation of the mixed grain region is due to the moderate cooling rate in this area, which promotes both the formation of equiaxed grains and the growth of columnar grains. It possesses certain strength, plasticity, and toughness. The columnar grain region is located in the middle of the billet, close to the surface but excluding the surface fine grain region. The grains in this region are columnar, growing along the direction of heat flow, usually perpendicular to the billet surface. The cooling rate of the molten steel is relatively fast in this region. The surface fine grain region is located in the outermost layer of the billet, closely adhering to the mold wall. Because the surface fine-grained zone cools extremely rapidly, the molten steel solidifies quickly, resulting in a small grain size. This small grain size contributes to high strength and hardness, while also exhibiting good plasticity and toughness, effectively reducing crack formation and improving the surface quality of the billet. During continuous casting, by optimizing cooling conditions (such as the flow rate of cooling water in the crystallizer and the distribution of cooling water in the secondary cooling zone) and controlling the casting speed, the solidification of each zone can be adjusted, thereby improving the overall quality and performance of the billet.

[0080] The aforementioned control method for stopping high-carbon, high-manganese steel continuous casting involves reducing the casting speed to the first target speed before stopping, and then removing the protective slag from the mold after stabilization. This ensures good lubrication between the inner wall of the mold and the billet, preventing mold adhesion and billet surface defects caused by residual protective slag, thus improving the service life of the mold and the surface quality of the billet. By adjusting the casting speed and cooling water flow rate in stages, the continuous casting process is made smoother, reducing fluctuations caused by sudden parameter changes and improving the stability of continuous casting. This also reduces surface cracks and internal defects in the billet caused by fluctuations in cooling water flow rate, helping to ensure billet quality. Activating the tail billet mode and disabling the light reduction function, as well as removing the submerged entry nozzle and adding cooling components, allows the tail billet to quickly detach from the mold at a suitable casting speed and cooling conditions, improving the efficiency of tail billet handling, reducing the dwell time of the tail billet in the fan-shaped section, and lowering the risks during tail billet handling. This invention achieves direct tailing out of high-carbon, high-manganese steel through the coordination of parameters and process modes. This avoids damage to the casting machine and its precision, and also avoids the waste slabs generated by mixed casting tailing out, thus generating good economic benefits.

[0081] This invention also provides a high-carbon, high-manganese steel. By rationally controlling the content of each component and precisely regulating the process parameters during the continuous casting shutdown process, the resulting high-carbon, high-manganese steel exhibits high strength, high toughness, and good wear resistance, showing broad application prospects. After work hardening, the surface hardness of the high-carbon, high-manganese steel reaches HB550 or higher, exhibiting high wear resistance and scratch resistance, thus extending the service life of components. It is suitable for applications in mining machinery, engineering machinery components, and other applications in high-wear environments. Moreover, the control method of this invention is easy to operate, reduces production costs, and is suitable for industrial continuous production.

[0082] In summary, the above-described technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for controlling high carbon high manganese steel continuous casting stoppage, characterized by the steps of include: S1: Before stopping casting, reduce the casting speed to the first target casting speed. After stabilizing, remove the protective slag in the crystallizer, close the stopper rod and set the blind plate. Simultaneously reduce the cooling water flow rate of the wide face of the crystallizer from the first target flow rate to the second target flow rate. S2: Switch the secondary cooling water system before the straightening section to semi-automatic locked flow mode to maintain the second target flow of cooling water, switch the first target pulling speed to the second target pulling speed, enable the tail billet mode and deactivate the light pressing function. S3: After removing the immersion nozzle, add a cooling component into the crystallizer and continuously pull out the tail billet at the third target pulling speed; S4: After the tail billet has completely left the crystallizer, run at the fourth target pulling speed for 2-4 minutes; then pull the tail billet out of the fan-shaped section at the fifth target pulling speed; The first target flow rate is 5100~6100 L / min; the second target flow rate is 4000~4500 L / min. The fifth target pulling speed > the fourth target pulling speed > the first target pulling speed ≥ the second target pulling speed ≥ the third target pulling speed; In step S4, if molten steel surges after the tail billet completely leaves the crystallizer, the tail billet is pulled out of the fan-shaped section directly at the fifth target pulling speed, and no shutdown operation is performed. In step S3, cooling springs and / or iron filings are selectively added depending on the solidification state of the tail billet.

2. The control method of high-carbon high-manganese steel continuous casting stoppage according to claim 1, characterized by, The first target pulling speed is 0.6~0.9 m / min; the second target pulling speed is 0.4~0.6 m / min; the third target pulling speed is 0.2~0.4 m / min; the fourth target pulling speed is 0.9~1.1 m / min; and the fifth target pulling speed is 1.2~2.0 m / min.

3. The method for controlling the shutdown of continuous casting of high-carbon, high-manganese steel according to claim 1, characterized in that, The cooling component is a rigid structure welded from cooling steel plates or flat steel.

4. The method for controlling the shutdown of continuous casting of high-carbon, high-manganese steel according to claim 1, characterized in that, It also includes inspecting the continuous casting machine after the tail billet is pulled out of the fan-shaped section to ensure that the accuracy of the continuous casting machine meets the standards.

5. The method for controlling the shutdown of continuous casting of high-carbon, high-manganese steel according to claim 1, characterized in that, In step S1, the first target flow rate is reduced to the second target flow rate at a rate of 50~100 L / min·s.

6. A high-carbon, high-manganese steel produced by the control method according to any one of claims 1 to 5, characterized in that, The composition of the high-carbon high-manganese steel, by mass percentage, includes: C 0.90~1.40%, Mn 11.0~14.0%, Si 0.30~0.70%, P≤0.035%, S≤0.020%, Al 0.015~0.10%, with the balance being Fe and unavoidable impurities.

7. The high-carbon, high-manganese steel according to claim 6, characterized in that, The high-carbon, high-manganese steel has a yield strength of 400-500 MPa, a tensile strength of 900-1000 MPa, and an elongation of ≥15%.

8. The high-carbon, high-manganese steel according to claim 6, characterized in that, The coefficient of linear expansion of the high-carbon, high-manganese steel at high temperatures is 1.5 to 2.0 times that of ordinary steel. The surface hardness after work hardening is HB550 or higher.

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