A method for controlling corner cracks in low-manganese peritectic steel continuously cast slabs
By employing methods such as dual control of primary cooling water, control of crystallizer liquid level, selection and use of protective slag, zoned regulation of secondary cooling water volume, and acceptance of crystallizer perpendicularity, the problem of corner cracks in low-manganese peritectic steel continuous casting slabs was solved, resulting in improved slab surface quality and reduced production costs.
Patent Information
- Application Number
- CN202610192455.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-26
AI Technical Summary
Low-manganese peritectic steel continuously cast slabs are prone to corner cracks during production. Existing methods require manual grinding, resulting in low production efficiency, high energy consumption, and waste of residual heat from the cast slab.
By implementing dual control of primary cooling water, control of liquid level in the crystallizer, selection and use of protective slag, zoned regulation of secondary cooling water volume, acceptance of crystallizer straightness, and adjustment of the straight guide section arc, the crystallizer and secondary cooling system are optimized to ensure uniform cooling and stable forming of the billet.
It effectively suppressed the generation and propagation of corner cracks in low-manganese peritectic steel continuous casting slabs, improved the surface quality of the slabs, realized direct hot delivery of the slabs, and reduced labor and energy costs.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of continuous casting production technology in iron and steel metallurgy, and in particular to a method for controlling corner cracks in low-manganese peritectic steel continuous casting slabs. Background Technology
[0002] Low-manganese peritectic steel continuously cast slabs are semi-finished slabs formed directly by continuous casting, with a carbon content in the peritectic range of 0.12%-0.16% and a manganese content controlled between 0.35%-0.9%. The production process includes steel preparation and refining, steel transportation and tundish transition, initial solidification in the crystallizer, secondary cooling and electromagnetic stirring, billet straightening, length cutting, and billet finishing. The initial solidification in the crystallizer relies on primary cooling water control, which involves precise regulation of parameters such as water volume and velocity in the crystallizer cooling water circuit to achieve rapid initial solidification of the molten steel surface. Secondary cooling is achieved through secondary cooling water dynamically distributed according to the billet solidification progress. The electromagnetic stirring process is typically integrated within the first sector section. The straight guide section is a straight-arc guide section immediately below the crystallizer, used to receive the initially solidified billet and provide stable guidance. The first sector section is the first arc-shaped section below the straight guide section, achieving a smooth transition of the billet from a straight to an arc shape. In actual production, the solidification stage within the crystallizer is a critical link in quality defect control. Due to the phase transformation volume shrinkage caused by peritectic transformation, the billet shell grows unevenly within the crystallizer. Simultaneously, early air gaps easily form between the billet shell and the crystallizer wall. These gaps cause instability and rapid deterioration in heat transfer, resulting in enormous thermal and structural stresses at the thinnest point of the high-temperature billet shell. Furthermore, the low manganese content cannot effectively counteract these stresses, leading to easy crack initiation on the billet surface, especially in the corner areas, severely affecting the billet surface quality. Current methods for removing corner cracks involve manual grinding after the billet has cooled. This manual grinding not only requires significant manpower but is also time-consuming and labor-intensive, reducing production efficiency. Moreover, the grinding must be performed after the billet has cooled, preventing hot charging and resulting in substantial waste of residual heat, increasing energy costs for subsequent heating processes. Therefore, how to provide a method for controlling corner cracks in low-manganese peritectic steel continuous casting slabs that can effectively suppress crack initiation and propagation, improve the surface quality of the slab, enable direct hot delivery of the slab, and reduce labor and energy costs is a new problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0003] This invention provides a method for controlling corner cracks in low-manganese peritectic steel continuous casting slabs. This method can solve the problem of corner cracks easily occurring in the production of existing low-manganese peritectic steel continuous casting slabs.
[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: the carbon content of the low-manganese peritectic steel continuous casting slab is 0.12%-0.16%, and the manganese content is 0.35%-0.9%; The corner crack control method is as follows: a. Dual control of cooling water: Based on the design parameters of the copper plate of the crystallizer and combined with the characteristics of low manganese peritectic steel, the cooling flow rate is selected (see Table 1). The core is to monitor the inlet and outlet water temperatures and adjust them in real time to maintain the temperature difference between the inlet and outlet water at 9.5℃-11℃, so as to ensure uniform cooling of the crystallizer and avoid stress cracks in the billet shell due to uneven cooling. b. Control of liquid level in crystallizer: Cooling water flows in from the bottom and out from the top, so that the upper part of the crystallizer is weakly cooled, and the liquid level in the crystallizer is controlled at 50 mm - 55 mm; to ensure that the billet shell grows evenly in the crystallizer and reduce stress concentration at the corners; c. Selection and use of protective slag: Select a protective slag with an alkalinity of 1.18, a melting point of 1047℃, a melting rate of 16s, and a moisture content of less than 0.18%. Control the total thickness of the protective slag to 50 mm - 60 mm. This total thickness is the sum of the thicknesses of the liquid slag layer, the sintering layer, and the powdered slag layer. This is to effectively lubricate the billet shell, isolate it from air to prevent oxidation, and improve the heat transfer between the crystallizer and the billet shell. d. Zoned control of secondary cooling water specific volume: The specific volume of secondary cooling water is divided into zones 1-5 and 6-9 with different intensities. The specific volume of zone 1-5 is controlled at 0.5 L / Kg - 0.6 L / Kg, and the specific volume of zone 6-9 is controlled at 0.8 L / Kg - 0.9 L / Kg; this is to match the cooling requirements of the billet at different solidification stages and avoid cracks in the billet due to excessive cooling rate. e. Double acceptance of crystallizer right angle: Use a standard right angle ruler of 200*300mm for offline acceptance and online measurement respectively. Use a feeler gauge to measure the gap between the right angle ruler and the copper plate of the crystallizer. The acceptance standard is that the gap between the right angle ruler and the copper plate of the crystallizer is ≤0.1mm. Offline acceptance: This is carried out after the crystallizer is overhauled. Measurements are taken at 50mm, 100mm, and 150mm from the top of the crystallizer. If the gap exceeds the standard, readjustment is required. Online measurement: This is performed after each adjustment of the planned cross-sectional thickness of the crystallizer. The measurement location is consistent with the offline acceptance measurement to ensure the accuracy of the crystallizer during online use. f. Adjustment of the arc alignment between the straight guide section and sector 1 section: After each shutdown or replacement of the straight guide section, adjust the arc alignment accuracy between the straight guide section and sector 1 section according to the preset arc alignment accuracy parameters. For the selection of specific arc alignment accuracy parameters, please refer to Table 2. The arc alignment should meet the requirements of the billet running during continuous casting to ensure that the billet is subjected to uniform force during operation and to avoid corner cracks caused by arc alignment deviation.
[0005] By adopting the above technical solution, the present invention has the following advantages compared with the prior art: 1. This control method is designed for low-manganese peritectic steel with a carbon content of 0.12%-0.16% and a manganese content of 0.35%-0.9%. It implements dual control of the flow rate and temperature difference of the primary cooling water, ensuring that the cooling water flows in from the bottom and out from the top. It precisely controls the liquid level in the crystallizer, selects suitable protective slag and controls its total slag layer thickness, regulates the specific water volume of the secondary cooling water in different zones, implements dual offline and online acceptance of the crystallizer's vertical angle, and standardizes the arc adjustment of the straight guide section and the first fan-shaped section. It comprehensively covers the key process links of continuous casting, effectively suppressing the generation and propagation of corner cracks in low-manganese peritectic steel continuous casting slabs, improving the surface quality of the slabs, reducing the scrap rate, and ensuring the stability and continuity of continuous casting production.
[0006] 2. Since the dual control of primary cooling water is based on the selected flow rate corresponding to the flow rate, the temperature difference between the inlet and outlet water is maintained in the range of 9.5℃-11℃ by real-time monitoring and dynamic adjustment of the inlet and outlet water temperatures. This ensures uniform and stable cooling of the copper plate in the crystallizer, avoids thermal stress concentration at the corners of the billet caused by excessively fast or slow local cooling, further improves the stability of the primary cooling water cooling effect, reduces the causes of corner cracks from the root, and ensures uniform growth of the billet shell.
[0007] 3. Since the total thickness of the protective slag is the sum of the thicknesses of the liquid slag layer, the sintering layer, and the powdered slag layer, the thickness of each functional layer of the protective slag can be precisely controlled. This avoids the impact of abnormal thickness of a single functional layer on the lubrication effect between the billet and the crystallizer or the uniformity of heat dissipation on the billet surface. It effectively reduces cracks at the corners of the billet caused by poor lubrication or uneven heat dissipation, and further optimizes the surface quality of the billet.
[0008] 4. Since the offline acceptance of the crystallizer's straightness is carried out after maintenance, and the online measurement is carried out after adjusting the planned cross-sectional thickness of the crystallizer, the crystallizer can maintain a qualified straightness after maintenance and cross-sectional adjustment. This avoids uneven extrusion pressure on the billet in the crystallizer due to crystallizer deformation or installation deviation, effectively preventing cracks at the corners of the billet due to uneven stress, and ensuring smooth billet formation during continuous casting.
[0009] 5. Since the alignment accuracy parameters of the straight guide section and the sector section 1 strictly meet the arc requirements of the billet running during continuous casting, local stress concentration caused by alignment deviation can be avoided when the billet enters the sector section 1 from the straight guide section. This ensures the smooth running of the billet, avoids friction and extrusion damage between the corner of the billet and the equipment, effectively reduces the probability of corner cracks in the billet, and ensures the stability of the billet's subsequent processing performance. Detailed Implementation
[0010] To make the above-mentioned objects, features, and advantages of the present invention more readily understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0011] Example 1 In this embodiment of the invention, low-manganese peritectic steel is produced by continuous casting on the No. 6 casting machine of the converter plant. The low-manganese peritectic steel has a carbon content of 0.14% and a manganese content of 0.6%.
[0012] The corner crack control method is as follows: a. Select the cooling flow rate based on the design parameters of the copper plate of the crystallizer and the characteristics of low-manganese peritectic steel (see Table 1), and control the temperature difference between the inlet and outlet of the cooling water at 10℃. b. Cooling water is introduced from the bottom and discharged from the top, and the liquid level in the crystallizer is controlled at 52mm. c. Select a protective slag with an alkalinity of 1.18, a melting point of 1047℃, a melting speed of 16s, and a moisture content of less than 0.18%, and control the total thickness to 55mm; d. The specific water volume of the secondary cooling water in zones 1-5 is controlled at 0.55 L / Kg, and the specific water volume in zones 6-9 is controlled at 0.85 L / Kg; e. A 200*300mm right-angle ruler was used to inspect the right angle of the crystallizer. The gap between offline and online measurements was controlled within 0.08mm to meet the accuracy requirements. f. After stopping the machine and replacing the straight guide section, adjust the alignment accuracy between the straight guide section and the sector 1 section according to the preset alignment accuracy parameters. For the specific alignment accuracy parameter selection, please refer to Table 2 to meet the straightness of the billet operation.
[0013] Production results show that the low-manganese peritectic steel continuous casting slabs produced using this method have no corner cracks, excellent surface quality, and can be directly hot-sent, reducing production costs by more than 15% compared to traditional processes.
[0014] Example 2 In this embodiment of the invention, low-manganese peritectic steel is produced by continuous casting on the No. 6 casting machine of the converter plant. The low-manganese peritectic steel has a carbon content of 0.12% and a manganese content of 0.35%.
[0015] The corner crack control method is as follows: a. Based on the design parameters of the copper plate of the crystallizer and combined with the characteristics of low manganese peritectic steel, select the cooling flow rate (see Table 1) and control the temperature difference between the inlet and outlet of the cooling water at 9.5℃; b. Cooling water is introduced from the bottom and discharged from the top, and the liquid level in the crystallizer is controlled at 52mm. c. Select a protective slag with an alkalinity of 1.18, a melting point of 1047℃, a melting speed of 16s, and a moisture content of less than 0.18%, and control the total thickness to 50mm. d. The specific water volume of the secondary cooling water in zones 1-5 is controlled at 0.5L / Kg, and the specific water volume in zones 6-9 is controlled at 0.8L / Kg; e. A 200*300mm right-angle ruler is used to inspect the right angle of the crystallizer. The gap between offline and online measurements is controlled within 0.1mm to meet the accuracy requirements. f. After stopping the machine and replacing the straight guide section, adjust the alignment accuracy between the straight guide section and the sector 1 section according to the preset alignment accuracy parameters. For the specific alignment accuracy parameter selection, please refer to Table 2 to meet the straightness of the billet operation.
[0016] Production results show that the low-manganese peritectic steel continuous casting slabs produced using this method have no corner cracks, excellent surface quality, and can be directly hot-sent, reducing production costs by more than 15% compared to traditional processes.
[0017] Example 3 In this embodiment of the invention, low-manganese peritectic steel is produced by continuous casting on the No. 6 casting machine of the converter plant. The low-manganese peritectic steel has a carbon content of 0.16% and a manganese content of 0.9%.
[0018] The corner crack control method is as follows: a. Select the cooling flow rate based on the design parameters of the copper plate of the crystallizer and the characteristics of low-manganese peritectic steel (see Table 1), and control the temperature difference between the inlet and outlet of the cooling water at 11℃. b. Cooling water is introduced from the bottom and discharged from the top, and the liquid level in the crystallizer is controlled at 55mm. c. Select a protective slag with an alkalinity of 1.18, a melting point of 1047℃, a melting speed of 16s, and a moisture content of less than 0.18%, and control the total thickness to 60mm. d. The specific water volume of the secondary cooling water in zones 1-5 is controlled at 0.6 L / Kg, and the specific water volume in zones 6-9 is controlled at 0.9 L / Kg; e. A 200*300mm right-angle ruler was used to inspect the right angle of the crystallizer. The gap between offline and online measurements was controlled within 0.06mm to meet the accuracy requirements. f. After stopping the machine and replacing the straight guide section, adjust the alignment accuracy between the straight guide section and the sector 1 section according to the preset alignment accuracy parameters. For the specific alignment accuracy parameter selection, please refer to Table 2 to meet the straightness of the billet operation.
[0019] Production results show that the low-manganese peritectic steel continuous casting slabs produced using this method have no corner cracks, excellent surface quality, and can be directly hot-sent, reducing production costs by more than 15% compared to traditional processes.
[0020] This invention can be modified and varied in various ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.
[0021] Table 1
[0022] Table 2 .
Claims
1. A method for controlling corner cracks in continuously cast low-manganese peritectic steel slabs, characterized in that: The low-manganese peritectic steel has a carbon content of 0.12%-0.16% and a manganese content of 0.35%-0.9%. Its control method is: a. Dual control of primary cooling water: Based on the design parameters of the copper plate of the crystallizer and combined with the characteristics of low manganese peritectic steel, the cooling flow rate is selected, and the temperature difference between the inlet and outlet of the primary cooling water is controlled at 9.5℃-11℃. b. Control of liquid level in crystallizer: Cooling water flows in from the bottom and out from the top, so that the upper part of the crystallizer is weakly cooled and the liquid level in the crystallizer is controlled at 50 mm - 55 mm. c. Selection and use of protective slag: Select a protective slag with an alkalinity of 1.18, a melting point of 1047℃, a melting rate of 16s, and a moisture content of less than 0.18%, and control the total thickness of the protective slag to 50 mm - 60 mm. d. Zonal control of secondary cooling water specific flow rate: The specific flow rate of secondary cooling water is divided into zones 1-5 and 6-9. The specific flow rate of zone 1-5 is controlled at 0.5 L / Kg - 0.6 L / Kg, and the specific flow rate of zone 6-9 is controlled at 0.8 L / Kg - 0.9 L / Kg. e. Double acceptance of crystallizer right angle: Offline acceptance and online measurement are carried out separately. During acceptance and measurement, a 200*300mm right angle ruler is used. At 50mm, 100mm and 150mm away from the top of the crystallizer, the gap between the right angle ruler and the copper plate of the crystallizer is measured with a feeler gauge. A gap ≤0.1mm is considered qualified. f. Arc alignment adjustment between the straight guide section and sector 1 section: After each shutdown or replacement of the straight guide section, adjust the arc alignment accuracy between the straight guide section and sector 1 section according to the preset arc alignment accuracy parameters.
2. The method for controlling corner cracks in low-manganese peritectic steel continuously cast slabs according to claim 1, characterized in that: The core of the dual control of the cooling water is to monitor the inlet and outlet water temperatures and adjust them in real time to maintain a stable temperature difference between the inlet and outlet water at 9.5℃-11℃, based on the selected cooling flow rate.
3. The method for controlling corner cracks in low-manganese peritectic steel continuously cast slabs according to claim 1, characterized in that: The total thickness of the protective slag is the sum of the thicknesses of the liquid slag layer, the sintering layer, and the powdered slag layer.
4. The method for controlling corner cracks in low-manganese peritectic steel continuously cast slabs according to claim 1, characterized in that: The offline acceptance test of the crystallizer's perpendicularity is conducted after the crystallizer is overhauled, while the online measurement is conducted after each adjustment of the crystallizer's planned cross-sectional thickness.
5. The method for controlling corner cracks in low-manganese peritectic steel continuously cast slabs according to claim 1, characterized in that: The arc alignment accuracy parameters of the straight guide section and the sector 1 section meet the arc requirements of the billet movement during continuous casting.