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Production method for preventing straightening and hot delivering cracks of microalloy continuous casting slab

A production method and technology of micro-alloyed steel, applied in the field of steelmaking, to achieve the effects of avoiding straightening crack defects, improving surface structure, and improving high-temperature plasticity

Active Publication Date: 2019-01-15
ZHANGJIAGANG RONGSHENG SPECIAL STEEL CO LTD +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It can be seen that there is still a lack of a rapid cooling method for continuous casting slabs that can effectively prevent microalloyed steel continuous casting slabs from straightening and hot delivery cracks.

Method used

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  • Production method for preventing straightening and hot delivering cracks of microalloy continuous casting slab
  • Production method for preventing straightening and hot delivering cracks of microalloy continuous casting slab
  • Production method for preventing straightening and hot delivering cracks of microalloy continuous casting slab

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] When producing aluminum-killed steel blooms with a cross-section of 300mm×390mm and the brand SCM435 (mass percentage of chemical composition: C: 0.35%, Al: 0.033%), the ordinary continuous casting cooling process is adopted to hot charge and heat the billet, and the billet is put into the furnace When the surface temperature was 738°C, after the bloom was opened into a billet, the occurrence rate of surface cracks was as high as 10.6%, such as figure 1 and image 3 shown. When the present invention is adopted, the surface temperature of the billet before rapid cooling is 920°C, the four-sided spray mode of full water spray is adopted, the cooling water volume is 280L / min, the spray pressure reaches 8.2MPa, the surface cooling rate is 5.8°C / s, and the rapid cooling Finally, the surface temperature of the billet is 420°C. After tempering, the surface temperature of the billet at the straightening position is 568°C. The highest surface temperature after tempering is 650°...

Embodiment 2

[0024] When producing aluminum-killed steel billets with a cross-section of 140mm×140mm and a grade of 10B21 (mass percentage of chemical composition: C: 0.22%, Al: 0.030%), the ordinary continuous casting cooling process is adopted to hot charge and heat the billets for straightening The corner temperature of the billet was 848°C. After the billet surface was pickled, many transverse crack defects were found at the corners, and the crack incidence rate reached 33.3%. After the billet was rolled, the wire rod returned to scrap aluminum as high as 3.8%. When the present invention is adopted, the full water spray mode is adopted, the cooling water volume is 260L / min, the spray pressure reaches 7.5MPa, and the surface cooling rate is 6.5°C / s. After rapid cooling, the billet surface temperature is 415°C. , The surface temperature of the billet at the straightening position is 566°C, no transverse crack defects at the corners were found in the pickling of the billet sample surface, ...

Embodiment 3

[0026] When producing 220mm×1260mm grade X70 (chemical composition mass percentage C: 0.06%, Nb: 0.07%) continuous casting slabs of pipeline steel containing Nb, the ordinary continuous casting cooling process is adopted, and the surface temperature of the slab at the straightening position is 906 ℃, the continuous casting slab blank inspection found that there are many surface transverse cracks at the corners, and the crack occurrence rate is as high as 15.2%. When the present invention is adopted, the steam-water four-sided spray mode is adopted, the cooling water volume is 350L / min, the spray pressure reaches 8.0MPa, and the surface cooling rate is 6.2°C / s. After rapid cooling, the billet surface temperature is 440°C. , The surface temperature of the blank at the straightening position is 587°C. After checking the continuous casting slab blank, no transverse crack defect at the corner was found.

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Abstract

The invention discloses a production method for preventing straightening and hot delivering cracks of a microalloy continuous casting slab. The production method comprises the following steps: quicklycooling the continuous casting slab before straightening, wherein the cooling rate is 5-10 DEG C / s and the surface temperature of the continuous casting slab is reduced to be lower than 450 DEG C; controlling the surface temperature of a blank in a straightening stage to be smaller than or equal to 600 DEG C; and carrying out temperature return control on the continuous casting slab which is straightened and is not cut, and controlling the surface temperature of the continuous casting slab after temperature return to be higher than the temperature of a steel type Ar3. The production method has the advantages that the hot filling and hot delivering quality and efficiency are improved while the surface quality of the continuous casting slab is improved.

Description

technical field [0001] The invention relates to the technical field of steelmaking, in particular to a production method for preventing micro-alloy steel continuous casting slab straightening and hot delivery cracks. Background technique [0002] During the continuous casting process, the cracks on the surface of the continuous casting billet are mainly divided into three categories: mold, continuous casting secondary cooling section and billet transportation, lifting, stacking and heating. Among them, the surface cracks formed in the crystallizer mainly include longitudinal cracks, transverse cracks and network cracks, etc.; the surface cracks formed in the secondary cooling section of continuous casting mainly include straightening transverse cracks, medium mechanical stress cracks and thermal stress cracks, etc.; billet transportation The surface cracks formed in the process of hoisting, stacking and heating mainly include phase transformation cracks and heat transfer cra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22D11/124B22D11/12
CPCB22D11/1213B22D11/124
Inventor 周青峰邹长东冯孔方皇祝平李解
Owner ZHANGJIAGANG RONGSHENG SPECIAL STEEL CO LTD
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