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Calcium treatment method for molten steel in steelmaking

A technology of calcium treatment and molten steel, which is applied in the field of calcium treatment of molten steel in steelmaking, can solve problems such as calcium instability, excessive steel plate inclusions, unevenness, etc., and achieve the effects of reducing quality problems, improving control levels, and improving economic benefits

Inactive Publication Date: 2010-12-22
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the high vapor pressure of calcium and the dead angle in the flow of molten steel in the ladle, the instability and inhomogeneity of calcium after calcium treatment in molten steel resulted in some inclusions in molten steel failing to become liquid and floating up to be removed, and eventually retained In the steel, the inclusion of the steel plate after rolling exceeds the standard and the flaw detection is unqualified, which reduces the yield of the steel plate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] The process of this embodiment is specifically as follows: the process route of molten iron pretreatment + converter smelting + LF furnace refining (first calcium treatment) + RH refining (second step calcium treatment) + continuous casting is adopted. After the molten iron pretreatment reaches the front of the furnace, the sulfur is 0.004%; the oxygen content of the molten steel at the end of the converter smelting is 972ppm, and the aluminum 1.8 kg / ton steel is added during the tapping process, and the slag is added at 8 kg / ton steel; after the molten steel reaches the LF furnace, lime and refined slag are added , Slag deoxidizer quickly produces white slag, and the weight percentage composition of refining slag after the slag is finished: binary alkalinity (CaO) / (SiO 2 ) is controlled at 5.3; (TFe+MnO)% is controlled at 2.8%; Al 2 o 3 % is controlled at 23.5%, adding aluminum grains or feeding aluminum wire to the molten steel in the early stage to adjust the total ...

Embodiment 2

[0020] The process of this embodiment is specifically as follows: the process route of molten iron pretreatment + converter smelting + LF furnace refining (first calcium treatment) + RH refining (second step calcium treatment) + continuous casting is adopted. After the molten iron pretreatment reaches the front of the furnace, the sulfur is 0.003%; the oxygen content of the molten steel at the end of the converter smelting is 860ppm, and the aluminum 1.6 kg / ton steel is added during the tapping process, and the slag is added at 8 kg / ton steel; after the molten steel reaches the LF furnace, lime and refined slag are added , Slag deoxidizer quickly produces white slag, and the weight percentage composition of refining slag after the slag is finished: binary alkalinity (CaO) / (SiO 2 ) is controlled at 5.8; (TFe+MnO)% is controlled at 2.5%; Al 2 o 3 % is controlled at 21.6%. Aluminum particles or aluminum wires are added to the molten steel in the early stage to adjust the total a...

Embodiment 3

[0023] The process of this embodiment is specifically as follows: the process route of molten iron pretreatment + converter smelting + LF furnace refining (first calcium treatment) + RH refining (second step calcium treatment) + continuous casting is adopted. After the molten iron pretreatment reaches the front of the furnace, the sulfur is 0.003%; the oxygen content of the molten steel at the end of the converter smelting is 658ppm, and the aluminum 0.9 kg / ton steel is added during the tapping process, and the slag is added at 8 kg / ton steel; after the molten steel reaches the LF furnace, lime and refining slag are added , Slag deoxidizer quickly produces white slag, and the weight percentage composition of refining slag after the slag is finished: binary alkalinity (CaO) / (SiO 2 ) is controlled at 6.2; (TFe+MnO)% is controlled at 1.8%; Al 2 o 3 % is controlled at 21%, adding aluminum particles or feeding aluminum wire to the molten steel in the early stage to adjust the tota...

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Abstract

The invention relates to a calcium treatment method for molten steel in steelmaking, which is the method for carrying out calcium treatment in two process steps in the steelmaking process route flow, and the steelmaking adopts the process route of pretreatment of molten iron plus smelting in a converter plus refining in an LF furnace plus RH refining plus continuous casting; the whole steelmaking process route adopts two times of calcium treatment; the first calcium treatment is to feed a calcium line into the molten steel to carry out the calcium treatment after finishing the LF treatment in the process step of refining in the LF furnace; and the second calcium treatment is to feed the calcium line into the molten steel to carry out the calcium treatment after finishing vacuum treatment in the process step of the RH refining. The application of the calcium treatment method for the molten steel in the steelmaking can respectively control the mass fractions of total oxygen and sulfur in a steel ball to be (5-20) multiplied by 106 and (2-30) multiplied by 106 respectively, most of inclusion in the steel ball is spherical, the equivalent diameter of the inclusion is (1-10) mu m, the qualified rate of the fault detection of a steel plate after rolling is larger than 99%, the B type inclusion grading is reduced as a whole, the proportion of the grade below grade 1 is 97%, and the control level of the inclusion is significantly improved.

Description

technical field [0001] The invention relates to a calcium treatment method for molten steel in steelmaking, in particular to a method for calcium treatment in two processes in the steelmaking process route flow. Background technique [0002] At present, it is generally used to feed a certain amount of calcium wire into the molten steel for calcium treatment at the end of the last refining process, and then stir it for a certain period of time to make the aluminum-based inclusions in the steel change from solid to liquid. Objects float up for easy removal. However, due to the high vapor pressure of calcium and the dead angle in the flow of molten steel in the ladle, the instability and inhomogeneity of calcium after calcium treatment in molten steel resulted in some inclusions in molten steel failing to become liquid and floating up to be removed, and eventually retained In the steel, the inclusion of the steel plate after rolling exceeds the standard and the flaw detection ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/00C21C7/10C21C7/06
Inventor 尹雨群赵晋斌孟令东吴伟勤韦士坤
Owner NANJING IRON & STEEL CO LTD
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