Method for controlling bloom continuous casting dynamic soft-reduction pressure interval

A control method and soft reduction technology, which is applied in the field of bloom continuous casting soft reduction technology, can solve problems such as unsuitable welding, lower welding performance, and large randomness, so as to shorten the development cycle, optimize the reduction interval, and achieve application effects stable effect

Inactive Publication Date: 2010-04-21
PANGANG GROUP RESEARCH INSTITUTE CO LTD +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Central segregation and porosity will seriously affect the performance of steel and cause a series of quality problems: for high-carbon wire rods, central porosity and segregation will lead to reduced drawability and increased breakage rate; for natural gas pipeline steel, hydrogen diffusion to segregation, In the loose part, cracks will be generated and expanded, which will eventually lead to the rupture of the pipe; for structural steel used in offshore drilling and platforms, the loose center and segregation will reduce its welding performance, and it is not suitable for welding, or even cracked.
At the same time, the existing theory does not conduct specific research on different steel types and slab sections, the range of reduction is wide, the randomness is large, and the application effect is unstable

Method used

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  • Method for controlling bloom continuous casting dynamic soft-reduction pressure interval
  • Method for controlling bloom continuous casting dynamic soft-reduction pressure interval
  • Method for controlling bloom continuous casting dynamic soft-reduction pressure interval

Examples

Experimental program
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Effect test

Embodiment 1

[0080] The slab is a high-strength weathering steel YQ450NQR1 slab with a cross-section of 360mm×450mm. The pouring superheat is 25°C, the casting speed is 0.6m / min, and the reduction range corresponds to the solid phase ratio of the slab center of 0.67-0.90. The weight percentages of solute elements of steel grades are shown in Table 1. Using a seven-stand rolling mill, when the reduction is 2mm, the minimum K of each solute element i The central solid fraction f at the corresponding section s，i opt and f s，Max opt , f s，Min opt As in Table 3, K i and each cross-section f of the slab s The corresponding relationship is as figure 1 , the horizontal axis is f s , the vertical axis is K i . After implementing the scheme, the carbon segregation index of the cross-section of the steel slab is improved from 0.90-1.09 to 0.94-1.05, and the carbon segregation index of the longitudinal section center is reduced from 1.04-1.14 to 1.02-1.09. The specific sampling points of t...

Embodiment 2

[0084] The billet is a billet of alloy structural steel 37Mn2 with a section of 360mm×450mm, the pouring superheat is 25°C, the casting speed is 0.6m / min, and the solid phase rate corresponding to the center of the billet is 0.72-0.92 in the reduction range. The weight percentages of solute elements of steel grades are shown in Table 2. Using a seven-stand rolling mill, when the reduction is 2mm, the minimum K of each solute element i The central solid fraction f at the corresponding section s，i opt and f s，Max opt , f s，Min opt As in Table 3, K i and each cross-section f of the slab s The corresponding relationship is as figure 2 , the horizontal axis is f s , the vertical axis is K i . After implementing the scheme, the carbon segregation index of the cross-section of the steel slab is improved from 0.87-1.12 to 0.91-1.07, and the carbon segregation index of the longitudinal section center is reduced from 1.06-1.19 to 1.04-1.09. The specific sampling points of t...

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Abstract

The invention discloses a bloom continuous casting soft-reduction process used in steel production, and in particular relates to a method for controlling a bloom continuous casting dynamic soft-reduction pressure interval. The pressure interval is determined according to the central solid-phase rate of each casting blank section in the direction of blank drawing; the central solid-phase rate of each casting blank section relative to the upper limit of the pressure interval is less than or equal to the fs, namely Maxopt which is the maximum value of iopt, of each solute element, wherein the fs and iopt are the central solid-phase rates of a casting blank section relative to the minimum Ki of the solute elements; the Ki is the average solute aliquation index of the solute element i in two phase regions when each casting blank section is slightly pressed; furthermore, the central solid-phase rate of each casting blank section relative to the lower limit of the pressure interval is more than or equal to the fs, namely Minopt which is the minimum value of iopt, of each solute element. The pressure interval determined by the method can effectively improve central aliquation and also reduce cavity, looseness and crack; and the pressure interval has stable use effect and is suitable for bloom continuous casting production.

Description

technical field [0001] The invention relates to a bloom continuous casting soft reduction process in iron and steel production, in particular to a method for controlling the bloom continuous casting dynamic soft reduction reduction interval. Background technique [0002] Generally, a billet with a cross-sectional size greater than 200mm×200mm is called a bloom. During the solidification process of the slab, the separation and crystallization characteristics of molten steel inevitably lead to the enrichment of solute elements in the intergranular liquid phase region, such as C, S, P, etc. At the same time, the continuous growth of the slab shell makes the molten steel rich in solute elements continuously move to the center of the slab; the molten steel at the center of the solidification end of the slab is rich in solute elements, and its fluidity decreases. At the end of the solidification of the slab, The molten steel in the center gradually transforms into a solid, causin...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22D11/16
Inventor 陈永朱苗勇张先胜罗森吴国荣祭程曾武
Owner PANGANG GROUP RESEARCH INSTITUTE CO LTD
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