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Method for reducing B inclusions in aluminium-free deoxidized steel

A technology for inclusions and aluminum deoxidation, applied in the field of reducing B-type inclusions in aluminum-free deoxidized steel, can solve problems such as waste judgment and increased production costs

Inactive Publication Date: 2019-01-08
武汉钢铁有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

During the production process, w(Alt) in molten steel ≥ 40×10 -6 The phenomenon occurs from time to time, and the average rate of B-type inclusions exceeding the standard is 2.63%, which leads to the degradation or even scrapping of high-speed heavy rails, and increases the production cost

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Process flow: injection desulfurization—converter blowing—LF furnace refining—RH furnace refining—billet continuous casting.

[0039] 1) Converter blowing process

[0040] Converter tapping carbon is controlled by a target value of 0.08% (the percentages below are all mass percentages unless otherwise specified), avoiding peroxidation tapping, and adopting low-aluminum-silicon-barium-calcium, ferrosilicon, and medium-carbon ferromanganese during tapping. Deoxidation alloying, slide plate is used to stop slag when tapping, converter controls the amount of slag, 400kg of lime is added when tapping (the total amount of molten steel is 120 tons, the same below), 80kg of fluorite, after the alloying of steel is completed, silicon in molten steel The content is controlled at 0.55%.

[0041] 2) Refining process of LF furnace

[0042] Lime and fluorite are added in batches to the slag heated by the LF furnace. The total amount of lime added is 400kg and the total amount of fl...

Embodiment 2

[0046] Process flow: injection desulfurization—converter blowing—LF furnace refining—RH furnace refining—billet continuous casting

[0047] 1) Converter blowing process

[0048] Converter tapping carbon is controlled according to the target value of 0.08% to avoid over-oxidation tapping. Low aluminum silicon barium calcium, ferrosilicon, and medium carbon ferromanganese are used for deoxidation alloying when tapping. Slag blocking is used when tapping. For the amount of slag, 400kg of lime and 80kg of fluorite are added when tapping the steel. After the steel is alloyed, the silicon content in the molten steel is controlled at 0.60%.

[0049] 2) Refining process of LF furnace

[0050] Lime and fluorite are added in batches to the slag heated by the LF furnace. The total amount of lime added is 400kg, and the total amount of fluorite is 80kg to ensure that the slag has good fluidity and the final slag basicity is controlled between 2.5 and 3.0. After deoxidizing the slag, contr...

Embodiment 3

[0054] Process flow: injection desulfurization—converter blowing—LF furnace refining—RH furnace refining—billet continuous casting

[0055] 1) Converter blowing process

[0056] Converter tapping carbon is controlled according to the target value of 0.08% to avoid peroxidation tapping. Low aluminum silicon barium calcium, ferrosilicon, and medium carbon ferromanganese are used for deoxidation alloying when tapping. Slag blocking is used when tapping. For the amount of slag, 400kg of lime and 80kg of fluorite are added when tapping the steel. After the steel is alloyed, the silicon content in the molten steel is controlled at 0.65%.

[0057] 2) Refining process of LF furnace

[0058] Lime and fluorite are added in batches to the slag heated by the LF furnace. The total amount of lime added is 400kg, and the total amount of fluorite is 80kg to ensure that the slag has good fluidity and the final slag basicity is controlled between 2.5 and 3.0. After deoxidizing the slag, contr...

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PUM

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Abstract

The invention discloses a method for reducing B inclusions in aluminium-free deoxidized steel. The method comprises the following steps: 1) converter steelmaking: overoxidation tapping is avoided; deoxidation alloying is performed by adopting low-aluminium SiBaCa, ferrosilicon and mid-carbon ferromanganese during tapping, lime and fluorite are added, and silicon content of molten steel is controlled to be 0.55wt%-0.65wt%; (2) LF (ladle furnace) refining: lime and fluorite are added in batches in heating slagging of the LF, and final slag basicity is controlled to be 2.0-3.0; silicon content ofmolten steel is controlled to be 0.60wt%-0.70wt%, and vacuum treatment starts after soft blowing with argon at rate of 80-200 L / min for 10-20 min; 3) RH furnace refining: an RH furnace is kept at ultimate vacuum degree for 15-25 min and subjected to vacuum killing, then argon flow is regulated to 150-250 L / min, argon is blown for 1-3 min, then the argon flow is regulated to 80-200 L / min, soft blowing is performed for 8-15 min, and a product is discharged from the furnace and loaded to a casting machine. Over-standard rate of the B inclusions in steel products is reduced by process improvement.

Description

technical field [0001] The invention relates to a method for improving the quality of aluminum-free deoxidized steel, in particular to a method for reducing B-type inclusions in aluminum-free deoxidized steel. Background technique [0002] Type B inclusions are the main cause of fatigue fractures in rails. The new iron standard requires inclusions in 350km / h high-speed heavy rails to require Type B to be ≤ level 1, w(Alt) ≤ 40×10 -6 . Aluminum-free deoxidation process is adopted, which can basically eliminate Al 2 o 3 Inclusions, to control Type B inclusions to a lower level. [0003] The Chinese patent application with the application number 201310629016.4 discloses a cost-effective aluminum-free deoxidation method for high-speed heavy rail steel. The method is to add deoxidizers at three different periods of a tapping cycle, and the deoxidizer added for the first time Agents include: metal manganese: 0.64-0.68%, special silicon: 0.19-0.24%, silicon-calcium-barium: 0.04...

Claims

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Application Information

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IPC IPC(8): C22C33/06C21C7/06C21C7/064C21C7/10
CPCC21C7/0087C21C7/06C21C7/064C21C7/10C22C33/06
Inventor 段光豪孟磊刘东清陈光友史万顺廖扬标吴义强
Owner 武汉钢铁有限公司
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