CN-122007360-A - Method for continuous casting of dissimilar steel by sharing same tundish

CN122007360ACN 122007360 ACN122007360 ACN 122007360ACN-122007360-A

Abstract

The invention provides a method for continuously casting dissimilar steel by sharing the same tundish, which is characterized by comprising the following process steps of 1) controlling the temperature of high-carbon molten steel to be 5-10 ℃ lower than the normal molten steel temperature when high-carbon steel is smelted and cast to a penultimate furnace, controlling the temperature of a continuous casting ladle to 1570-1575+/-7 ℃, 2) pouring the penultimate furnace high-carbon molten steel to the continuous casting tundish through the continuous casting ladle, raising the molten steel level of the tundish, 3) pouring a covering agent into the continuous casting tundish after the slag discharge of the penultimate furnace high-carbon molten steel is finished in the continuous casting tundish, and 4) replacing a quick water outlet of the continuous casting tundish with a water outlet of phi 17.5mm before the last furnace high-carbon molten steel is poured, and reducing the pulling speed from 2.5m/min to 2.0m/min.

Inventors

TAO JIANYONG
SU GUOWU
NIU YU
LIN JIAN
HONG RONGKUN
SHI LI
DAI CHUNLIN
ZHANG LIN

Assignees

武钢集团昆明钢铁股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260115

Claims (4)

1. A method for continuous casting of dissimilar steel by sharing the same tundish, which is characterized by comprising the following process steps: 1) When the high-carbon steel is smelted and cast to the penultimate furnace, controlling the temperature of the high-carbon molten steel to be 5-10 ℃ lower than the normal molten steel, and controlling the temperature of a continuous casting ladle to 1570-1575+/-7 ℃; 2) After pouring the high-carbon molten steel of the penultimate furnace into a continuous casting tundish through a continuous casting ladle, raising the liquid level of the molten steel of the tundish until slag is discharged at the molten steel side of the tundish, reducing the slag content in the molten steel of the tundish and improving the purity of the molten steel; 3) After slag discharge of the penultimate high-carbon molten steel is finished in the continuous casting tundish, adding a covering agent with the following chemical components in percentage by mass, namely 5-10% of C, less than or equal to 5% of SiO 2 ：33-43%,CaO：13-23%,MgO≤7%,Al 2 O 3 ≤7%,Fe 2 O 3 and 10-20% of fluxing agent into the continuous casting tundish until the liquid level of the molten steel is not exposed, preventing the molten steel from being cooled and avoiding the exposed molten steel from being secondarily oxidized; 4) Before the final high-carbon steel water casting, the quick water inlet of the continuous casting tundish is replaced by a water inlet with phi 17.5mm, and the pulling speed is reduced from 2.5m/min to 2.0m/min so as to weaken the solidification temperature change, the shrinkage change and the strength change of the casting blank shell in the connection stage; 5) When the final high-carbon molten steel is cast into a continuous casting tundish through a continuous casting ladle, controlling the temperature of the molten steel to be 10-20 ℃ higher than the normal molten steel, and controlling the temperature of the continuous casting ladle to 1590-1600+/-7 ℃; 6) When the final furnace high-carbon molten steel is poured into a continuous casting tundish through a continuous casting ladle, 5-10% of a covering agent C, less than or equal to 5% of SiO 2 ：33-43%,CaO：13-23%,MgO≤7%,Al 2 O 3 ≤7%,Fe 2 O 3 and 10-20% of a fluxing agent in percentage by mass are put into the continuous casting tundish until the liquid level of the molten steel is kept bare continuously; 7) Before the continuous casting ladle is poured, the high carbon steel casting powder in the casting powder bin is replaced by the low carbon steel casting powder until the continuous casting of the high carbon steel is completed; 8) When the low-carbon steel water of the first furnace is cast into a continuous casting tundish through a continuous casting ladle, controlling the secondary cooling intensity K value of continuous casting to be increased from 1.12 to 1.25, and adding low-carbon steel mold flux into a crystallizer until the thickness of a liquid slag layer reaches 8-12mm; 9) And after the first furnace low-carbon steel water is poured into the continuous casting tundish through the continuous casting ladle, controlling the liquid level of the molten steel in the continuous casting tundish to be lower than the normal liquid level, and then smelting and casting the low-carbon steel grade continuously until the last furnace low-carbon steel water is poured into the continuous casting tundish through the continuous casting ladle until the low-carbon steel continuous casting is completed.
2. The method for continuous casting of dissimilar steel sharing the same tundish according to claim 1, wherein the high carbon steel mold flux and the low carbon steel mold flux are all conventional mold fluxes.
3. The method for continuous casting of dissimilar steel sharing the same tundish according to claim 1, wherein the last furnace high carbon molten steel is characterized in that before the continuous casting tundish is completely cast, the residual quantity of the high carbon molten steel in the tundish is controlled to be less than or equal to 15t, the residual quantity of the high carbon molten steel in the tundish is reduced, and the subsequent low carbon molten steel can be replaced quickly after entering the tundish.
4. The method for continuous casting of dissimilar steel sharing the same tundish according to claim 1, wherein after the first furnace low-carbon molten steel is cast into the continuous casting tundish by the continuous casting ladle, the liquid level of the molten steel in the continuous casting tundish is controlled to be lower than the normal liquid level, so that the inclusion in the low-carbon molten steel has sufficient floating space, and the inclusion is conveniently removed.

Description

Method for continuous casting of dissimilar steel by sharing same tundish Technical Field The invention relates to the technical field of billet continuous casting, in particular to a method for continuous casting of dissimilar steel by sharing the same tundish so as to reduce the continuous casting loss of the dissimilar steel. Background In recent years, with the change of the demand mode of steel market users, the planned production is carried out according to sales orders, and the method has become a main production mode of steel enterprises, in the mode, the production of steel making procedures is changed from the production of products with the same steel grade and specification and a long period into the production of products with the same steel grade and different specifications, under the same yield requirement, the mode has the advantages that the number of continuous casting tundish is increased, the energy consumption caused by the frequent start and stop of converters, refining furnaces and continuous casting machines on a main production line is increased, the production operation rate is reduced, and the steelmaking cost control, the operation efficiency and the labor intensity of workers are greatly influenced. In particular, in the industrial wire production process, as the production of large-scale production is not achieved, a tundish which is available for 30 hours is often used, the production plan is completed only in 12 hours, and then the tundish is replaced to produce another product with the steel grade specification for 12 hours, so that on one hand, the utilization rate of the tundish is less than 50%, on the other hand, the number of the new tundish is increased, and further difficulty is brought to steelmaking cost control. With the continuous increase of industrial wire yield, varieties and specifications, the production mode that different types of steel share the same tundish can fundamentally solve the contradiction that the utilization rate of the tundish is less than 50% on one hand and the quantity of the tundish is increased on the other hand in the prior art, and lay an operation foundation for the subsequent 'product differentiation' production. However, in the production process of realizing that dissimilar steels share the same tundish, as the chemical components of different steel types are not completely the same, such as HPB300 and Q195 steel types, due to the large difference of carbon content, factors such as temperature change, drawing speed change, cooling change, blank shell shrinkage change and the like exist in the joining process, production fluctuation such as steel leakage, water-junction and the like is extremely easy to cause, and quality fluctuation is further generated, which is a difficulty in continuous casting production of dissimilar steels sharing the same tundish. Accordingly, there is a need for improvements in the art. Disclosure of Invention Aiming at the problems existing in the prior art, the invention provides a method for continuously casting dissimilar steel which is suitable for mass production of multiple steel types, low in cost and controllable in quality by combining the produced steel types and adopting the modes of process control, operation optimization and the like. The invention is completed by the following technical scheme that the method for continuous casting of dissimilar steel by sharing the same tundish comprises the following process steps: 1) When the high-carbon steel is smelted and cast to the penultimate furnace, controlling the temperature of the high-carbon molten steel to be 5-10 ℃ lower than the normal molten steel, and controlling the temperature of a continuous casting ladle to 1570-1575+/-7 ℃; 2) After pouring the high-carbon molten steel of the penultimate furnace into a continuous casting tundish through a continuous casting ladle, raising the liquid level of the molten steel of the tundish until slag is discharged at the molten steel side of the tundish, reducing the slag content in the molten steel of the tundish and improving the purity of the molten steel; 3) After slag discharge of the penultimate furnace high-carbon molten steel is completed in the continuous casting tundish, a covering agent with the following chemical components in percentage by mass of 5-10% of C, less than or equal to 5% of SiO 2：33-43%,CaO：13-23%,MgO≤7%,Al2O3≤7%,Fe2O3 and 10-20% of fluxing agent is put into the continuous casting tundish. Until the liquid level of the molten steel is not exposed, the molten steel is prevented from being cooled, and the exposed molten steel is prevented from being oxidized secondarily; 4) Before the final high-carbon steel water casting, the quick water inlet of the continuous casting tundish is replaced by a water inlet with phi 17.5mm, and the pulling speed is reduced from 2.5m/min to 2.0m/min so as to weaken the solidification temperature change, the shrinkage change and the strength change