CN114603096A - Continuous casting process for controlling carbon segregation of 82B steel - Google Patents

Abstract

The invention discloses a continuous casting process for controlling carbon segregation of 82B steel, which changes the process conditions into that: the secondary cooling ratio water amount before optimization is 0.45L/Kg, the solidification coefficient is about 24.5, the liquid core thickness is 60mm when the continuous casting blank enters the position of the tail end electromagnetic stirring body, the solidification coefficient is improved by adjusting the secondary cooling ratio water amount, the secondary cooling ratio water amount is adjusted to 0.65L/Kg, the solidification coefficient is about 26, and the liquid core thickness is 50mm when the continuous casting blank enters the position of the tail end electromagnetic stirring body. In order to control the central carbon segregation of the 82B steel continuous casting slab, the continuous casting pouring speed of the 82B steel is limited to 1.8 m/min. In the production process, the pouring speed of the first furnace steel is controlled according to 1.6-1.7m/min when the machine is started, the secondary continuous casting pouring degree of the continuous casting furnace is controlled according to 1.8m/min constant drawing speed, the temperature in the molten steel process of the 82B steel ladle is reduced, and meanwhile, through the use of the ladle capping technology, the temperature drop of the molten steel in the pouring process of the first furnace steel can be effectively controlled within the range of 15 ℃, and the temperature of the secondary molten steel of the continuous casting furnace is controlled within 1485 and 1500 ℃.

Description

Continuous casting process for controlling carbon segregation of 82B steel

Technical Field

The invention relates to a continuous casting process for controlling carbon segregation of 82B steel.

Background

With the improvement of the requirements of market clients on the steel quality, the steel enterprises are promoted to continuously optimize the process flow so as to obtain high-quality steel products. 82B is a high-quality wire rod, and in order to obtain a high-quality wire rod, it is required that the ingot has a small amount of inclusions, a small particle size of inclusions, a small center carbon segregation, and a good surface quality. The carbon segregation of the continuous casting blank has great influence on the quality of 82B products, and can cause the generation of reticular cementite in rolled stock, the drawing fracture can occur near the reticular cementite in the drawing process, and the product quality can not meet the use requirements of customers. Since the development of the 82B steel grade, the control of the carbon segregation of the 82B steel continuous casting slab is an important task.

The first steel plant of eight steel companies, Limited, Xinjiang, was put into operation in 8 months of 2012, and built with one 150t top-bottom combined blown converter, one 150tLF finer, and one 150mm x 150mm billet (10 machine 10 stream) continuous caster. The specific process flow of steel making is as follows: a molten iron reladling station, a KR desulfurization station, a converter, an LF refining furnace and a billet caster. Eight steel production 82B chemistry is shown in the table below.

The process control in the actual production process of continuous casting comprises the following steps:

1. the conditions of the electromagnetic stirring control parameters are as follows

The distance from the center of the end electromagnetic stirring body to the meniscus is 6.75 meters.

2. Temperature pull rate conditions are as follows

1. 3, controlling the cooling water flow of the crystallizer to be 120 +/-5 m/h, carrying out weak cooling on secondary cooling water, controlling the secondary cooling specific water quantity to be 0.45L/Kg, and controlling the superheat degree of the molten steel in the tundish to be 15-30 ℃.

The adoption of the process has the problems that the central carbon segregation of the continuous casting billet is serious, the central carbon segregation index of the continuous casting billet reaches more than 1.10, the condition that the net-shaped cementite is serious appears in a rolled material, the condition that a user frequently breaks a wire during drawing in the using process occurs, and the existing process can not meet the using requirements of the user.

And (3) searching documents: the problems of reducing the carbon segregation of 82B steel are solved by methods of controlling the superheat degree of molten steel, improving the strength of secondary cooling water, optimizing tail end electromagnetic stirring parameters and the like according to periodicals such as 82B high-carbon steel continuous casting billet center segregation and wire quality, 82B casting billet missing analysis and quality improvement, and influence of continuous casting parameters and tail end electromagnetic stirring on 82B steel small square billet center carbon segregation, and mainly relate to theoretical research.

Disclosure of Invention

The invention aims to provide a continuous casting process for controlling the carbon segregation of 82B steel, which determines proper secondary cooling water distribution through the position of end electromagnetic stirring, fully plays the role of the end electromagnetic stirring, effectively controls the central carbon segregation of the 82B steel within the range of 1.05 and ensures that the 82B steel meets the use requirements of users.

The invention adopts the technical scheme that a continuous casting process for controlling the carbon segregation of 82B steel is changed into the following process conditions: the secondary cooling specific water amount before optimization is 0.45L/Kg, the solidification coefficient is about 24.5, the liquid core thickness is 60mm when the continuous casting blank enters the position of the tail end electromagnetic stirring body, the solidification coefficient is improved by adjusting the secondary cooling specific water amount, the secondary cooling specific water amount is adjusted to 0.65L/Kg, the solidification coefficient is about 26, and the liquid core thickness is 50mm when the continuous casting blank enters the position of the tail end electromagnetic stirring body;

in order to control the center carbon segregation of the 82B steel continuous casting slab, the continuous casting pouring speed of the 82B steel is limited to 1.8m/min, and the adjusted drawing speed table is as follows:

in the production process, the pouring speed of the first furnace steel is controlled according to 1.6-1.7m/min when the machine is started, the secondary continuous casting pouring degree of the continuous casting furnace is controlled according to 1.8m/min constant drawing speed, the temperature in the molten steel process of the 82B steel ladle is reduced, and meanwhile, through the use of the ladle capping technology, the temperature drop of the molten steel in the pouring process of the first furnace steel can be effectively controlled within the range of 15 ℃, and the temperature of the secondary molten steel of the continuous casting furnace is controlled within 1485 and 1500 ℃.

By adopting the measures, the center carbon segregation index of the 82B steel continuous casting billet is reduced to 1.05 from 1.10, the problem of rolled stock net carbon caused by center carbon segregation of the continuous casting billet is solved, the problem of drawing breakage caused by net carbon is solved, and the requirement of user quality use is met. Through an optimization process, according to the electromagnetic stirring position at the tail end of the current continuous casting machine, the continuous casting secondary cooling water distribution is optimized (the specific water amount of the secondary cooling water is adjusted to 0.65L/Kg from the original 0.45L/Kg), the effect of the electromagnetic stirring at the tail end is fully exerted, so that the aim of reducing the carbon segregation of 82B steel is fulfilled, the temperature and the drawing speed control (the superheat degree is controlled to be 15-30 ℃) during the 82B steel production is well performed, and the constant drawing speed control (1.8 m/min) is realized during the pouring process.

Detailed Description

A continuous casting process for controlling the carbon segregation of 82B steel is characterized in that the process conditions are changed as follows: the secondary cooling ratio water amount before optimization is 0.45L/Kg, the solidification coefficient is about 24.5, the liquid core thickness is 60mm when the continuous casting billet enters the position of the tail-end electromagnetic stirring body through calculation, the solidification coefficient is improved by adjusting the secondary cooling ratio water amount, the secondary cooling ratio water amount is adjusted to 0.65L/Kg, the solidification coefficient is about 26, and the liquid core thickness is 50mm when the continuous casting billet enters the position of the tail-end electromagnetic stirring body.

Under the condition that other processes are not changed, along with the lifting of the drawing speed, the liquid core length of the continuous casting billet is increased, the liquid core thickness when the continuous casting billet enters the tail end electromagnetic stirring body is increased, the current tail end electromagnetic stirring position is fixed, when the drawing speed reaches 1.9m/min, the liquid core thickness when the continuous casting billet enters the tail end electromagnetic stirring body reaches 58mm, the effect of the tail end electromagnetic stirring is not favorably and fully exerted, and the continuous casting pouring speed of 82B steel is limited to 1.8m/min for controlling the central carbon segregation of the 82B steel continuous casting billet. The adjusted pull rate table is as follows:

in the production process, the pouring speed of the first furnace steel is controlled according to 1.6-1.7m/min when the machine is started, the secondary continuous casting pouring degree of the continuous casting furnace is controlled according to 1.8m/min constant drawing speed, the temperature in the molten steel process of the 82B steel ladle is reduced, and meanwhile, through the use of the ladle capping technology, the temperature drop of the molten steel in the pouring process of the first furnace steel can be effectively controlled within the range of 15 ℃, and the temperature of the secondary molten steel of the continuous casting furnace is controlled within 1485 and 1500 ℃.

Claims (1)

1. A continuous casting process for controlling the carbon segregation of 82B steel is characterized in that the process conditions are changed as follows: the secondary cooling specific water amount before optimization is 0.45L/Kg, the solidification coefficient is about 24.5, the liquid core thickness is 60mm when the continuous casting blank enters the position of the tail end electromagnetic stirring body, the solidification coefficient is improved by adjusting the secondary cooling specific water amount, the secondary cooling specific water amount is adjusted to 0.65L/Kg, the solidification coefficient is about 26, and the liquid core thickness is 50mm when the continuous casting blank enters the position of the tail end electromagnetic stirring body;

in order to control the central carbon segregation of the continuous casting slab of the 82B steel, the continuous casting speed of the 82B steel is limited to 1.8m/min, and the adjusted casting speed is shown as follows:

in the production process, the pouring speed of the first furnace steel is controlled according to 1.6-1.7m/min when the machine is started, the secondary continuous casting pouring degree of the continuous casting furnace is controlled according to 1.8m/min constant drawing speed, the temperature in the molten steel process of the 82B steel ladle is reduced, and meanwhile, through the use of the ladle capping technology, the temperature drop of the molten steel in the pouring process of the first furnace steel can be effectively controlled within the range of 15 ℃, and the temperature of the secondary molten steel of the continuous casting furnace is controlled within 1485 and 1500 ℃.