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A method for controlling inclusions in ultra-low carbon steel based on a straight cylinder vacuum refining device

A technology of vacuum refining and device control, which is applied in the field of steelmaking, and can solve the problems of easy adhesion of inclusions on the nozzle wall, high alkalinity, and impossibility of slag-gold reaction.

Active Publication Date: 2020-07-31
MAANSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Fe in reducing top slag above molten steel in RH vacuum chamber t The content of O is low and the alkalinity is high. During the RH refining process, the reducing top slag is relatively "stationary", the molten steel and the reducing top slag are basically not stirred and mixed, and the slag-gold reaction cannot proceed, so the reducing property in the vacuum chamber cannot be used. Top slag removes Al from molten steel 2 o 3 The inclusions are spheroidized and transformed into low-melting calcium-aluminate inclusions, and the solid Al in molten steel 2 o 3 The inclusions are easy to collide and grow into large-sized inclusions in the continuous casting process after RH vacuum refining. When the molten steel is poured into the crystallizer through the tundish nozzle 2 o 3 Inclusions are easy to stick to the nozzle wall, causing the nozzle to accumulate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] This embodiment adopts the following scheme, including the following steps:

[0023] (1) The final molten steel volume of the converter is 119.5 tons, the temperature is 1635℃, the molten steel [C]: 0.038%, a[O]: 762ppm, the tapping does not deoxidize, and the bottom of the ladle is blown with argon during tapping; after tapping is completed, Transfer the ladle to the position of the straight-tube vacuum refining device, slowly lift the ladle, the top slag in the ladle spreads over the lower edge of the dip tube, and then slowly vacuumize the ladle top slag into the vacuum chamber for 1 min, and the pressure in the vacuum chamber is maintained At 15000Pa; then open the argon blowing nozzles evenly arranged on the circumference of the immersion pipe wall, the argon blowing flow rate of each nozzle is equal, and the total blowing argon flow rate is 3NL / t.min;

[0024] (2) Slowly lift the ladle until the dip tube is inserted 50mm below the molten steel level in the ladle, adjus...

Embodiment 2

[0032] This embodiment adopts the following scheme, including the following steps:

[0033] (1) The final molten steel volume of the converter is 121.3 tons, the temperature is 1629℃, the molten steel [C]: 0.038%, a[O]: 762ppm, the tapping does not deoxidize, the bottom of the ladle is blown with argon during tapping; after tapping is completed, Transfer the ladle to the position of the straight-tube vacuum refining device, slowly lift the ladle, the top slag surface of the ladle spreads over the lower edge of the dip tube, and then slowly draw the vacuum to suck the ladle top slag into the vacuum chamber for 1.5 minutes, and the pressure in the vacuum chamber Keep it at 14000Pa; then turn on the argon blowing nozzles evenly arranged on the wall of the immersion tube. The argon blowing flow rate of each nozzle is equal, and the total blowing argon flow rate is 3NL / t.min;

[0034] (2) Slowly lift the ladle until the dip tube is inserted 50mm below the molten steel level in the ladle...

Embodiment 3

[0042] This embodiment adopts the following scheme, including the following steps:

[0043] (1) The final molten steel volume of the converter is 120.8 tons, the temperature is 1640℃, the molten steel [C]: 0.035%, a[O]: 728ppm, the tapping does not deoxidize, and the bottom of the ladle is blown with argon during tapping; after tapping is completed, Transfer the ladle to the straight-tube vacuum refining device station, slowly jack up the ladle, the top slag in the ladle spreads over the lower edge of the dip tube, and then slowly draw a vacuum to suck the ladle top slag into the vacuum chamber for 2 minutes, and the vacuum degree of the vacuum chamber Keep it at 20000Pa; then turn on the argon blowing nozzles evenly arranged on the circumference of the immersion pipe wall, the argon blowing flow of each nozzle is equal, and the total blowing argon flow is 3NL / t.min;

[0044] (2) Slowly lift the ladle until the dip tube is inserted 50mm below the molten steel level in the ladle, ad...

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Abstract

The invention discloses a method for controlling inclusion in ultra-low carbon steel based on a straight cylinder type vacuum refining device. The method comprises the following steps that a steel ladle is conveyed to a straight cylinder type vacuum refining station and jacked; a dipping pipe is inserted below the liquid level of molten steel by 50 mm, an argon blowing nozzle, on the same side asa steel ladle eccentric bottom blowing nozzle, of the semi-circumference of the wall of the dipping pipe is adjusted to blow argon strongly, and an argon blowing nozzle on the different size is adjusted to blow argon weakly; the dipping pipe is inserted below the liquid level of the molten steel by 200 mm, and the steel ladle is opened for eccentric bottom argon blowing; the dipping pipe is inserted below the liquid level of the molten steel by 400-500 mm, and rapidly pumped to the limit vacuum degree; the argon blowing flow is adjusted slightly until top slag is pushed to the weak blowing side of the wall of the dipping pipe to the minimum area; after decarbonization treatment is carried out, a molten steel sample is taken for oxygen fixation, then molten steel deoxidization treatment iscarried out, and CaO / Al2O3 in a top slag system is controlled to be equal to 1.2-2.0; and after air breaking, the steel ladle is opened. According to the method, Al2O3 inclusion generated by deep deoxidization is transformed into calcium aluminate low-melting-point inclusion, the amount of the Al2O3 inclusion in the continuous casting molten steel is reduced, thus the adhesion amount of the Al2O3inclusion on the wall of a water opening in the process of the molten steel poured into a crystallizer by passing through a tundish water opening is reduced, and occurrence of flow accumulation of thewater opening is avoided.

Description

Technical field [0001] The invention relates to the technical field of steelmaking, in particular to a method for controlling inclusions in ultra-low carbon steel based on a straight-tube vacuum refining device. Background technique [0002] The size, quantity and type of inclusions in molten steel have a decisive influence on product quality. Therefore, an important way to improve the quality of steel products includes minimizing the number of various inclusions in molten steel, and harmlessly removing the inclusions that cannot be removed. 化处理. For high-quality steel with carbon content below 0.03%, the control of inclusions in the steel is mainly achieved through LF furnace refining; during the LF furnace refining process, there is a slag reaction between the top slag of the ladle and the molten steel: x[Me]+ y[O]=(Me x O y ), there is an inclusion reaction between molten steel and inclusions: x[Me]+y[O]=(Me x O y ), when these two reactions are close to equilibrium, then It ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21C7/10C21C7/072
CPCC21C7/072C21C7/10
Inventor 沈昶乌力平张良明郭俊波陆强潘远望解养国张晓峰李想舒宏富孙彪
Owner MAANSHAN IRON & STEEL CO LTD
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