Method for controlling impurity in ultra low carbon IF steel

A technology of inclusions and ultra-low carbon, which is applied in the field of steelmaking, refining and continuous casting, can solve the problems of affecting the flow field of molten steel, the high oxidation of ladle top slag, the occurrence of bias flow and crystallizer slag entrainment, etc., so as to reduce surface defects and solve the problem of The problem of continuous casting flow storage and the effect of improving cleanliness

Active Publication Date: 2010-06-30
MAANSHAN IRON & STEEL CO LTD
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

[0002] When using the "converter-alloy fine-tuning station-RH-continuous casting" process route to produce ultra-low carbon IF steel series steel grades, due to the difficulty in coordinated control of the converter end point C, end point temperature T, and active oxygen a[O], ladle top slag Oxidation is high, the total oxygen T.O of molten steel is high after RH refining, and the content of FeO and MnO in slag is still high, which leads to the phenomenon of easy flow accumulation in the continuous casting process, affecting the flow field of molten steel, occurrence of bias flow and mold slag entrainment, etc. It not only affects the cleanliness of molten steel but also affects the continuous casting and it is difficult to realize continuous casting of multiple furnaces

Method used

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Experimental program
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Effect test

Embodiment 1

[0019] (1) The control ranges of the converter end point C, end temperature T and activity oxygen a[O] are respectively, C: 0.025%, end temperature T: 1686°C and activity oxygen a[O]: 405 ppm. The converter adopts static model + sub-lance model to achieve coordinated control of endpoint C, endpoint temperature T and activity oxygen a[O]. The simultaneous hit rate of endpoint C, endpoint temperature T and activity oxygen a[O] reaches 89.78%.

[0020] (2) For DC04 and DC06 steel grades, 1200kg lime and 150kg fluorite are added to the tapping. In the argon blowing station, under the condition of red slag, add 900kg of ladle top slag reduction modifier through a rotating distributor. The chemical composition of the modifier is MAl: 35-60%, CaCO 3 : 15-30% and CaO: 10-35%.

[0021] (3) After RH deoxidation and alloying, the net cycle time is controlled at 6min to ensure that the total oxygen T.O content at the RH end point is 30ppm, and the endogenous inclusions in the steel are Al with...

Embodiment 2

[0025] (1) The control ranges of the converter endpoint C, endpoint temperature T and activity oxygen a[O] are respectively, C: 0.06%, endpoint temperature T: 1690°C and activity oxygen a[O]: 650 ppm. The converter adopts static model + sub-lance model to achieve coordinated control of terminal C, terminal temperature T and activity oxygen a[O]. The simultaneous hit rate of terminal C, terminal temperature T and activity oxygen a[O] reaches 91.52%.

[0026] (2) For DC04 and DC06 steel grades, 600kg lime and 300kg fluorite are added to the tapping. In the argon blowing station, under the condition of red slag, add 1800kg ladle top slag reduction modifier through a rotating distributor. The chemical composition of the modifier is MAl: 35-60%, CaCO 3 : 15-30% and CaO: 10-35%.

[0027] (3) After RH deoxidation and alloying, the net cycle time is controlled above 7min to ensure that the total oxygen T.O content at the RH end point is 21ppm, and the endogenous inclusions in the steel are...

Embodiment 3

[0031] (1) The control ranges of the converter endpoint C, endpoint temperature T and activity oxygen a[O] are respectively, C: 0.04%, endpoint temperature T: 1700°C and activity oxygen a[O]: 800 ppm. The converter adopts static model + sub-lance model to achieve coordinated control of endpoint C, endpoint temperature T and activity oxygen a[O]. The simultaneous hit rate of endpoint C, endpoint temperature T and activity oxygen a[O] reaches 92.01%.

[0032] (2) For DC04 and DC06 steel grades, 1800kg lime and 200kg fluorite are added to the tapping. In the argon blowing station, under the condition of red slag, add 1200kg of ladle top slag reducing modifier through a rotating distributor. The chemical composition of the modifier is MAl: 35-60%, CaCO 3 : 15-30% and CaO: 10-35%.

[0033] (3) After RH deoxidation and alloying, the net cycle time is controlled above 8min to ensure that the total oxygen T.O content at the RH end point is 35ppm, and the endogenous inclusions in the steel ...

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Abstract

The invention provides a method for controlling impurity in ultra low carbon IF steel, including the following steps: (1) control ranges of converter finishing point C, T and a[0] are determined, converter finishing point C is controlled to be 0.02-0.06%, T is controlled to be 1685-1700 DEG C, and a[0] is controlled to be 400-800ppm; (2) steel ladle top residue modification treatment is carried out, namely lime and fluorite are added in converter tapping process, steel ladle top residue modifier is added at argon flushing station, ratio of CaO / Al2O3 in residue after modification is ensured tobe controlled to be 1.2-1.8, and TFe content in residue is less than 8%; (3) RH finishing point molten steel T.O is reduced, namely net cycle time after RH deoxidation alloying is controlled to be more than 6 minutes, and RH finishing point T.O content is ensured to be less than 40ppm; (4) double layer covering agent is adopted for pouring protection in continuous casting of middle ladle; (5) a stopper rod is adopted for argon blowing technology.

Description

Technical field [0001] The invention belongs to the field of steelmaking, refining and continuous casting in iron and steel metallurgy, and particularly relates to a method for controlling inclusions in ultra-low carbon IF steel. Background technique [0002] When using the "converter-alloy fine-tuning station-RH-continuous casting" process route to produce ultra-low carbon IF steel grades, it is difficult to coordinate the control of the converter endpoint C, endpoint temperature T and activity oxygen a[O], and ladle top slag High oxidation, high total oxygen TO in molten steel after RH refining, high FeO and MnO content in the slag, resulting in easy accumulation in the continuous casting process, affecting the flow field of molten steel, drifting and mold slag entrapment, etc. It not only affects the cleanliness of molten steel, but also affects continuous casting. It is not easy to realize multiple furnace continuous casting. Summary of the invention [0003] In order to over...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/06
Inventor 沈昶刘学华舒宏富张晓峰潘远望陶承岗金友林
Owner MAANSHAN IRON & STEEL CO LTD
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