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Method for controlling non-metallic inclusions in steel

A technology for non-metallic inclusions and quantity control, which is applied in the fields of gear steel, high-quality spring steel, pipeline steel, and non-metallic inclusions in control steel, which can solve the problem of many calcium-aluminate non-metallic inclusions, etc. The effect of reducing the scrap rate

Active Publication Date: 2011-02-02
SHOUGANG CORPORATION
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Problems solved by technology

[0005] The purpose of the present invention is to provide a method for controlling non-metallic inclusions in steel to solve the problem that calcium-aluminate-type non-metallic inclusions produced after calcium treatment do not have more time to discharge molten steel, causing calcium-aluminate in the slab The problem of many salt non-metallic inclusions

Method used

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  • Method for controlling non-metallic inclusions in steel
  • Method for controlling non-metallic inclusions in steel
  • Method for controlling non-metallic inclusions in steel

Examples

Experimental program
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Embodiment

[0018] Embodiment (4 heats test results)

[0019] 210 tons of oxygen double-blown converter, adding 1100kg of aluminum and iron (aluminum content: 40wt%), 1800kg of lime, 400kg of fluorite, slagging material (CaO: 90wt%, Al 2 o 3 : 10wt%) 500kg. After tapping, the molten steel [Al] contents in the four heats were 0.035wt%, 0.047wt%, 0.052wt%, and 0.042wt%, respectively. The intensity is 1150Nl / min.

[0020] During the LF smelting process, 200kg of aluminum particles are added to the surface of the slag to reduce the FeO content in the slag. The composition of the slag in the ladle of the 4 heats is shown in Attached Table 2.

[0021] After slagging, carry out bottom blowing Ar strong stirring desulfurization, the bottom blowing intensity is 1000Nl / min, and the time is 15 minutes. After bottom blowing and strong stirring desulfurization, the sulfur content of molten steel in the four heats is controlled to be 0.0006wt%, 0.0006wt%, 0.0008wt%, 0.0007wt%, and the total oxygen...

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Abstract

The invention discloses a method for controlling non-metallic inclusions in steel, and belongs to the field of steelmaking and refining control. Two-section calcium treatment and soft blow are adopted during the refining, and the calcium treatment and the soft blow are performed at the end of LF refining and RH vacuum treatment respectively, so that the non-metallic inclusions in a casting blank are classified into two types: 70 to 90 percent of non-metallic inclusions with CaS as main components, and 10 to 30 percent of oxide type non-metallic inclusions, wherein all the non-metallic inclusions in the casting blank are spherical; the particle diameters of all the non-metallic inclusions in the casting blank are controlled within a range of 0 to 5 microns; and the number of the non-metallic inclusions with the diameter of greater than 3 microns in the casting blank is controlled within the range of 0 to 5 / cm<2>. Thus, the problem that the calcium aluminate type non-metallic inclusion produced after the calcium treatment cannot be discharged out of molten steel due to insufficient time, so the content of calcium aluminate type non-metallic inclusions in the casting blank is high is solved. The rejection rate caused by super-standard non-metallic inclusion of the low alloy structural steel is reduced.

Description

technical field [0001] The invention relates to a method for controlling non-metallic inclusions in steel, which belongs to the technical field of steelmaking, and is especially suitable for high-quality spring steel, gear steel, pipeline steel, etc. that require vacuum treatment and have strict requirements on inclusions. Background technique [0002] In the production process of high-quality alloy structural steel, in order to avoid Al in steel 2 o 3 The harm of inclusions and the maintenance of castability of molten steel, the main method is to carry out calcium treatment on molten steel to control the composition of non-metallic inclusions in steel in the lower melting point region 12CaO·7Al 2 o 3 Nearby; in the production process of pipeline steel, the purpose of calcium treatment is not only to denature oxide inclusions, but also to avoid MnS inclusions in molten steel, and to avoid MnS inclusions caused by S segregation during solidification. [0003] In the proces...

Claims

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Application Information

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IPC IPC(8): C21C5/28C21C7/00
Inventor 李海波崔阳朱国森张永青杨健李飞李明刘风刚亢小敏
Owner SHOUGANG CORPORATION
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