Method for improving center segregation of ultra-thick slab peritectic steel

A thick slab and center point technology, which is applied in the field of improving the center segregation of ultra-thick slab peritectic steel, can solve the problem of not being able to effectively improve the internal quality of ultra-thick slabs and not considering the influence of solidification characteristics of W-shaped liquid cores in continuous casting of slabs and other problems, to achieve the effect of obvious internal quality improvement, easy realization, and simple process

Inactive Publication Date: 2021-02-19
MINMETALS YINGKOU MEDIUM PLATE
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  • Abstract
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Problems solved by technology

[0003] The invention patent with the patent number CN201811567253.1 discloses a dynamic secondary cooling and light reduction control system for slabs. amount and reduction interval, dynamically optimize the roll gap value of each reduction segment, and achieve the purpose of reducing slab center segregation and center porosity defects." The solidification characteristics of the W-shaped liquid core in slab continuous casting and its influence on the center segregation of the cast slab, while the W-shaped solidification end of the ultra-thick slab is more prominent, and a specific center segregation control technology must be adopted for the final solidification area
[0004] During the first 480mm straight-arc ultra-thick slab continuous casting practice in China, it was found that the central segregation and W-shaped solidification end of the ultra-thick slab were more serious than those of the medium-thick slab, and the conventional light reduction technology could not be effective Improve the internal quality of ultra-thick slabs. At present, there is no reference experience for high-quality ultra-thick slabs with a thickness of 480mm in China. We can only continue to explore, optimize and innovate in production practice

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  • Method for improving center segregation of ultra-thick slab peritectic steel

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Embodiment 1

[0035] Ultra-thick slab peritectic steel with a thickness specification of 460mm and a carbon content of 0.096wt% was selected for treatment. The composition of the steel grade is as follows: C0.096, Si 0.197, Mn 1.478, P 0.022, S 0.002, Als 0.025. In the continuous casting process, the ultra-thick slab is pressed, and the specific steps are as follows:

[0036] (1) In the two-phase region, when 0.05 ≤ fs <0.35, the reduction is 4.5mm; when 0.35 ≤ fs <0.55, the reduction is 5.0mm; when 0.55 ≤ fs <0.90, the reduction is 6.5mm ; When 0.90 ≤ fs ≤ 1.0, the reduction is 8.0mm; in the solid phase region, when dt≤80℃, the reduction is 5mm.

[0037] (2) When this scheme is adopted, the central segregation ratings of the 1 / 4, 1 / 2, and 3 / 4 positions of the slab width are all C1.0, and the internal quality of the ultra-thick slab peritectic steel is significantly improved.

Embodiment 2

[0039] For ultra-thick slab peritectic steel with a thickness specification of 480mm and a carbon content of 0.091wt%, the composition of the steel grade is as follows: C 0.091, Si 0.192, Mn 1.486, P 0.014, S 0.002, Als 0.025. In the continuous casting process, the ultra-thick slab is pressed, and the specific steps are as follows:

[0040] (1) In the two-phase region, when 0.05 ≤ fs <0.35, the reduction is 1.0mm; when 0.35 ≤ fs <0.55, the reduction is 1.5mm; when 0.55 ≤ fs <0.90, the reduction is 2.0mm ; When 0.90 ≤ fs ≤ 1.0, the reduction is 3.0mm; in the solid phase region, when dt≤80℃, the reduction is 1.5mm.

[0041] (2) When this scheme is adopted, the central segregation ratings of the 1 / 4, 1 / 2, and 3 / 4 positions of the slab width are all C1.0, and the internal quality of the ultra-thick slab peritectic steel is significantly improved.

[0042] The method of the present invention adopts a 475mm ultra-thick slab casting machine, and through a specific pressing process, ...

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Abstract

The invention provides a method for improving center segregation of ultra-thick slab peritectic steel. The method is used for carrying out reduction treatment on an ultra-thick slab and comprises thefollowing steps that 1) reduction treatment is carried on a two-phase region, firstly, a solid fraction of a casting blank is calcaulted according to a formula fs=(Tl-T1) / (T1-TS), and secondly, a reduction amount is determined according to the solid fraction; and 2) reduction treatment is carried on the solid-phase region, firstly, temperature difference of a reduction position of the casting blank is calculated according to a formula dt=TS-T2, and secondly, a reduction amount is determined according to the temperature difference: when dt is greater than 80 DEG C, reduction is not carried out,and when dt is less than or equal to 80 DEG C, a reduction amount falls within 1.5-5.0 mm. The method has the advantages that the process is simple, and the method is easy to implement and can be implemented by the aid of existing equipment. When the scheme is adopted, center segregation ratings of 1 / 4, 1 / 2 and 3 / 4 positions of a width of the casting blank are C1.0, and internal quality of the ultra-thick slab peritectic steel is obviously improved.

Description

technical field [0001] The invention belongs to the technical field of steelmaking and continuous casting, and in particular provides a method for improving the center segregation of ultra-thick slab peritectic steel for the continuous casting production of ultra-thick slab with a thickness specification exceeding 450 mm. Background technique [0002] Usually, people classify slabs with a thickness greater than 450mm as ultra-thick slabs, and steels with a carbon content in the range of 0.09%≤C(wt%)<0.14% are classified as peritectic steels. During the solidification process of slab continuous casting, there are two defects that cannot be eliminated. One is the unavoidable center segregation due to fractional crystallization, and the other is the W-shaped solidification end during the solidification process of the slab. The causes and hazards of slab continuous casting center segregation have been elaborated in detail in many domestic and foreign literatures; as for the W...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22D11/16
CPCB22D11/16
Inventor 甄新刚赵和明陈勇李大伟陈晨孙建鹏温雨邱进明
Owner MINMETALS YINGKOU MEDIUM PLATE
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