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Rapid decarburization method for RH refined ultra-low carbon steel

An ultra-low carbon steel, fast technology, applied in the field of steelmaking, can solve the problems of long refining time, slow vacuum decarburization speed, and large process temperature drop, and achieve short refining time, fast vacuum decarburization speed, and process temperature drop small effect

Inactive Publication Date: 2022-04-01
HANDAN IRON & STEEL GROUP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] In order to achieve the above conditions in the converter, the molten steel condition at the beginning of the RH refining treatment is high [C], low [O] molten steel, and the content of [C] in the early stage of RH refining is relatively high. is reduced to 0.0070%, and [C]+1 / 2O 2 =CO reaction, the flow rate of oxygen used must be compatible with the transmission speed of [C] inside the molten steel to the surface of the molten pool, and the transfer of [O] from the inside of the molten steel to the surface of the molten pool becomes the limiting link for decarburization, and the speed of vacuum decarburization is slow. Long time, large process temperature drop

Method used

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  • Rapid decarburization method for RH refined ultra-low carbon steel
  • Rapid decarburization method for RH refined ultra-low carbon steel
  • Rapid decarburization method for RH refined ultra-low carbon steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] Embodiment 1: The method for rapid decarburization of ultra-low carbon steel refined by RH adopts the following specific processes.

[0040] The tapping capacity of the converter is 275 tons, the carbon content of the molten steel is 0.052wt%, the P content is 0.011wt%, the S content is 0.0085wt%, the tapping temperature is 1660°C, and the end point oxygen is 485ppm; the tapping temperature is 1 / 3 Add lime particles to the ladle according to the addition of 550kg; the particle size of the lime particles is 3-5mm, the content of calcium oxide is 92%, and the activity is 380ml; after the steel is tapped, the slag layer is in a molten state, so add 550kg aluminum slag, the metal aluminum content is 40% in the described aluminum slag.

[0041] After the molten steel reaches RH, measure the temperature to determine the oxygen and carbon content: the oxygen content is 285ppm, the carbon content is 0.042w%, and the temperature is 1608°C; select the RH pre-vacuum mode, and pump...

Embodiment 2

[0045] Embodiment 2: The method for rapid decarburization of ultra-low carbon steel refined by RH adopts the following specific process.

[0046] The steel output of the converter is 274 tons, the carbon content of the molten steel is 0.045wt%, the P content is 0.013wt%, and the S content is 0.0072wt%. Add lime particles to the ladle according to the addition of 685kg; the particle size of the lime particles is 3-5mm, the content of calcium oxide is 90.2%, and the activity is 330ml; 680kg aluminum slag, the metal aluminum content is 42% in the described aluminum slag.

[0047] After the molten steel reaches RH, measure the temperature and determine the oxygen and carbon content: the oxygen content is 357ppm, the carbon content is 0.04w%, and the temperature is 1607°C; select the RH pre-vacuum mode, and pump the vacuum to 120mbar; lift the ladle, dip the tube Insert it 400mm below the liquid steel surface, start the vacuum pump, start the exhaust, and the vacuum degree is 150m...

Embodiment 3

[0051] Embodiment 3: The method for rapid decarburization of ultra-low carbon steel refined by RH adopts the following specific process.

[0052] The steel output of the converter is 275 tons, the carbon content of the molten steel is 0.045wt%, the P content is 0.012wt%, and the S content is 0.0079wt%. Add lime particles to the ladle according to the addition of 960kg; the particle size of the lime particles is 3-4mm, the content of calcium oxide is 94%, and the activity is 372ml; Carry out strong stirring to ensure that the slag layer is completely melted and then close the bottom blowing of the ladle, and add 825kg of aluminum slag in the ladle, the metal aluminum content in the aluminum slag is 41%.

[0053] After the molten steel reaches RH, measure the temperature to determine the oxygen and carbon content: the oxygen content is 504ppm, the C content is 0.040%, and the temperature is 1605°C; select the RH pre-vacuum mode, and pump the vacuum to 125mbar; jack up the ladle,...

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Abstract

The invention discloses a rapid decarburization method for RH refined ultra-low carbon steel. The method comprises the following steps: (1) when a converter stops blowing, the carbon content is 0.045-0.060 wt%, the P content is less than or equal to 0.015 wt%, the O content is 0.035-0.055 wt%, and the final temperature is 1670 + / -10 DEG C, performing converter tapping; (2) adding 2.0-3.5 kg / t of lime particles into a steel ladle when and after tapping to 1 / 3; (3) after tapping, according to the melting condition of a slag layer in the steel ladle, if the slag layer is in a molten state, directly adding 2.0-3.0 kg / t of aluminum slag into the steel ladle; and if the slag layer crusts, a steel ladle bottom blowing device is opened for strong stirring, the steel ladle bottom blowing device is closed after the slag layer is completely melted, and then 2.0-3.0 kg / t of aluminum slag is added. By the adoption of the method, the carbon content of RH outbound molten steel can be controlled to be 0.0015 wt% or below within 15 minutes in vacuum, and the defects that when ultra-low carbon steel is used for treating high [C] and low [O] molten steel, the decarburization speed is low, and the refining time is long are overcome; the method has the advantages of high vacuum decarburization speed, short decarburization time, short refining time, small process temperature drop, low content of FeO in top slag, high component hit rate and the like.

Description

technical field [0001] The invention belongs to the technical field of steelmaking, in particular to a method for rapid decarburization of RH refined ultra-low carbon steel. Background technique [0002] Ultra-low carbon steel refers to pure steel containing [C]<100ppm in steel. In addition to the conventional chemical composition that must be strictly controlled according to the standard, there are strict requirements on the number, size, and shape of inclusions in the steel. Endogenous inclusions in ultra-low carbon steel mainly refer to inclusions of Al 2 o 3 class, large Al with a size above 10 μm 2 o 3 Inclusions can form surface defects in cold-rolled steel sheets. After RH refining and decarburization, after adding aluminum for deoxidation and during continuous casting and pouring, the high content (FeO) in the slag will react with [Al] in the molten steel, [Al] + (FeO) = (Al 2 o 3 )+[Fe], thus significantly increasing the Al 2 o 3 inclusion content. Durin...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/10C21C7/00C21C7/06C21C7/068
Inventor 许韬高福彬汤海明刘彬赵艳玲陈达黄洪涛
Owner HANDAN IRON & STEEL GROUP
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