A vacuum refining process for molten steel
A technology for vacuum refining and molten steel, applied in the field of molten steel refining technology, can solve the problems of secondary pollution of molten steel, influence of production organization, energy waste, etc., and achieve the effects of reducing energy waste, reducing power consumption for refining, and reducing the frequency of return heating
Active Publication Date: 2015-11-25
NANJING IRON & STEEL CO LTD
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Problems solved by technology
There is no heat supplement for the ladle during vacuum treatment, so vacuum treatment is a cooling process, the average temperature drop is 2.5°C / min, and the total temperature drop during vacuum treatment is above 75°C, so a higher molten steel temperature is required before vacuum treatment, which increases the The power consumption of the refining furnace leads to energy waste. If the temperature of the molten steel after vacuum treatment is not enough, it must be returned to the refining furnace for heating treatment, resulting in secondary pollution of the molten steel and a great impact on the production organization.
Method used
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Experimental program
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Effect test
Embodiment 1
[0010] The invention provides a vacuum refining process for molten steel, including LF refining and vacuum treatment, and the above processes are controlled as follows:
[0011] (1) In the LF refining process, high-grade silicon carbide is used for deoxidation throughout the process. After the molten steel reaches the LF level and the chemical slag is supplied for ≥ 3 minutes, high-grade silicon carbide is added before the first sampling, and the addition amount is 40-50kg; the first sampling Continue to add high-grade silicon carbide during the power supply after the second sampling, the addition amount is 30-50kg; add high-grade silicon carbide in the power supply stage after the second sampling, the addition amount is 20-30kg, control the alkalinity of the refining furnace slag to 2-5, through this The operation can reduce the oxidation of molten steel, improve the fluidity of slag, avoid thicker slag crusts, and prevent serious slag splashing during vacuum treatment.
[00...
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The present invention relates to a metallurgical refining process, and relates to a vacuum refining process for molten steel. The vacuum refining process for molten steel comprises LF refinement and vacuum treatment. SiC is used for deoxidation by the refinement process. SiC is added in three times. 40-50 kg is added in a first time; 30-50 kg is added in a second time; and 20-30 kg is added in a third time, so that basicity of slag in a refining furnace is controlled at 2-5. In the vacuum treatment process, argon is introduced into a vacuum furnace after the molten steel enters the vacuum furnace, a flow volume of the argon is controlled at about 500 L / min; after 10 to 20 seconds, the argon flow volume is adjusted to 20-50 L / min; when the vacuum degree is higher than or equal to 100 Pa, the argon flow volume is controlled at 30-60 L / min; and when the vacuum degree in the vacuum furnace is less than 67 Pa, a high vacuum stage is preformed, the argon flow volume is adjusted to 80-120 L / min after the high vacuum stage is preformed for 1-2 min, and the argon flow volume is adjusted to 10-35 L / min after 10-18 min; and thus the vacuum treatment can be finished. The process reduces a total time of vacuum treatment, reduces refining electricity consumption, and guarantees hydrogen content of the molten steel lower than or equal to 2.0 ppm. Besides, and temperature drop of the molten steel during the vacuum treatment process is small.
Description
technical field [0001] The invention relates to a molten steel refining process, in particular to a vacuum refining process of molten steel, belonging to the technical field of metallurgy. Background technique [0002] During the smelting process of molten steel, due to the use of raw and auxiliary materials, refractory materials, alloys, etc., the content of gas dissolved in molten steel increases, and the gas dissolved in steel precipitates during solidification and precipitation, which easily causes shrinkage cavities, white spots, cracks, Subcutaneous air bubbles, central porosity, segregation, etc., and the gas that will not be precipitated in the future will reduce the strength, reduction of area, elongation and impact toughness of the steel. Most high value-added steel types, such as bearings, springs, steel for automobile machinery, forged steel, and steel for oil drill collars and drilling tools, have strict requirements on the gas content in molten steel. In order ...
Claims
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IPC IPC(8): C21C7/10C21C7/06
Inventor 王国柱李凯
Owner NANJING IRON & STEEL CO LTD