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A Method for Reducing Bubble Defects in Slabs of Cr-Containing Steels

A technology for steel types and slabs, which is applied in the field of reducing bubble defects in slabs of Cr-containing steel types, can solve problems such as defects in hot-rolled materials, and achieve the effect of improving product quality

Active Publication Date: 2020-07-17
ANGANG STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to provide a method for reducing bubble defects in steel slabs containing Cr ≥ 0.15% in slabs and to solve defects in slabs and hot-rolled steels containing Cr≥0.15%

Method used

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  • A Method for Reducing Bubble Defects in Slabs of Cr-Containing Steels
  • A Method for Reducing Bubble Defects in Slabs of Cr-Containing Steels

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Embodiment 1 produces the operation control method of slab SS400Cr (width=1280mm):

[0027] 1) The argon gas in the tundish is operated at a small flow rate. The argon gas flow rate of the tundish stopper rod is controlled at 1.2NL / min, and the argon gas flow rate at the upper nozzle is controlled at 1.0NL / min.

[0028] 2) The cross-section is 170*1280mm, the casting speed is 1.9m / min, and the single-flow steel volume is controlled at 3.24 tons / min.

[0029] 3) Three-hole submerged nozzles are used, the inclination angle of the nozzles on both sides is 15°, and the ratio of the vertical hole steel area to the total steel area is 10% (see attached figure 1 ).

[0030] 4) The superheat of the molten steel in the tundish is not less than 18°C, and the target superheat is 23°C.

[0031] 5) The distance from the upper edge of the outlet hole of the submerged nozzle to the molten steel surface of the mold is 120-140mm.

Embodiment 2

[0032] Embodiment 2 produces the operation control method of slab A36-Cr (width=1700mm):

[0033] 1) The argon gas in the tundish is operated at a small flow rate. The argon gas flow rate of the tundish stopper rod is controlled at 1.5NL / min, and the argon gas flow rate at the upper nozzle is controlled at 1.2NL / min.

[0034] 2) The cross-section is 170*1700mm, the casting speed is 1.5m / min, and the single-flow steel volume is controlled at 3.40 tons / min.

[0035] 3) Use two-hole submerged nozzles, no vertical holes, and the inclination angle of the nozzles on both sides is 20° (see attached figure 2 ).

[0036] 4) The superheat of molten steel in the tundish is not less than 20°C, and the target superheat is 25°C.

[0037] 5) The distance from the upper edge of the outlet hole of the submerged nozzle to the molten steel surface of the mold is 130-150mm.

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Abstract

The invention relates to a method for reducing a bubble defect of a slab Cr-containing steel grade casting blank. Argon gas in a tundish is operated at a small flow rate, the argon gas flow rate of astopper rod in the tundish is less than or equal to 2.0 NL / min, and the argon gas flow rate of an upper nozzle is less than or equal to 2.0 NL / min; in the casting process, the minimum single-flow steel passing is not less than 2.4 tons / min; when the slab width is less than or equal to 1500 mm, three-hole immersive nozzle is used for continuous casting, the inclination angle of the holes in both sides is at 15 degrees, and the area ratio of vertical hole steel passing to the total steel passing is 5-18%; when the slab width is larger than 1500 mm and is small than or equal to 2200 mm, a two-hole immersive nozzle without vertical holes are used for continuous casting, and the inclination angle of the nozzle of water in the two holes are at 20 degrees; the superheat degree of molten steel ofthe tundish is not less than 12 DEG C; and the distance from the top edge of a discharge hole of the immersive nozzle to the liquid level of the molten steel in a crystallizer is 100-160 mm. Accordingto the method, the bubble defect generated by steel grades containing Cr more than or equal to 0.15% is avoided, and the defect of edge portion "peeling"-like formed by bubble exposure rolling elongation in the casting blank rolling process is eliminated. The product quality of the steel grade is improved.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to a method for reducing bubble defects in slabs of Cr-containing steels. Background technique [0002] The fourth branch of Angang Steelmaking General Plant produces slabs containing Cr (Cr ≥ 0.15%) steel grades with a relatively high proportion. Due to the relatively high viscosity of molten steel containing Cr in slabs, the argon bubbles blown into the crystallizer during the production process are easy to be slab Shell capture, during the rolling process of the slab, the air bubbles are exposed and rolled to elongate to form a "skin-like" defect on the edge. The thinner the rolled specification, the more obvious the defect. Due to the high output of Cr-containing steels in slabs and the high frequency of edge bubble defects, and most of them are exported products, the quality requirements are more stringent and urgently need to be resolved. Contents of the invention [000...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22D11/103B22D11/117B22D11/18
CPCB22D11/103B22D11/117B22D11/18
Inventor 徐向阳左继双张相春陈志威徐博
Owner ANGANG STEEL CO LTD
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