Control method of soft-reduction depressed region of wide and thick plate continuous casting blank

Abstract

The invention relates to a control method of a soft-reduction depressed region of a wide and thick plate continuous casting blank. The control method is implemented according to the following steps that (1) the non-uniform solidified tail end morphology is determined; (2) the soft-reduction depressed starting point and finishing point positions of the continuous casting blank in different width positions are determined; (3) the soft-reduction depression rate is regulated: the soft-reduction depression rate is set to be 0.8 to 2.2mm / m in a region Pend-Pend<1 / 2>; the soft-reduction depression rate is set to be 0.4 to 1.6 mm / m in a region Pend<1 / 2>-Pend. The control method provided by the invention is adopted for setting the soft-reduction depression rate, aiming at a determining method of the soft-reduction depressed region of a solidified blank case of the wide and thick plate continuous casting blank under the non-uniform growth condition, the implementation effect of a soft-reduction process is ensured, the segregation and loosening defects of a cross section center line of the wide and thick plate continuous casting blank can be effectively overcome, and good application prospects are realized.

Description

technical field [0001] The invention relates to a soft-reduction control method of continuous casting technology, in particular to a control method for a soft-reduction interval of a wide-thick plate continuous casting slab. Background technique [0002] Slab soft reduction technology refers to the application of pressure (thermal stress and mechanical stress) near the end of continuous casting slab solidification to generate a certain amount of reduction to hinder the flow of molten steel containing enriched segregation elements, thereby eliminating central segregation and compensating for continuous casting. Solidification shrinkage of the slab to eliminate center porosity. [0003] The reduction range of soft reduction is the key process parameter to determine the position of soft reduction, and it is mostly expressed as the solid phase ratio range of the center line of continuous casting slab; All the same; the representative published research results are as follows: a...

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Problems solved by technology

[0005] The above studies all use the solid phase ratio of the centerline of the continuous casting slab to characterize the soft reduction reduction range; however, in the slab continuous casting production process, due to the uneven lateral distribution of the secondary cooling water, the shell at the end of solidification often appears uneven growth phenomenon ; Especially for wide and thick slab continuous casting slabs, due to the increase in section size, the phenomenon of liquid core extension in the range of 1 / 4 to 1 / 8 of the slab width is very obvious. The lower position and length cannot improve the entire section, especially the macro-segregation defects in the 1 / 4 to 1 / 8 area

[0006] In 2011, Metalurgia International Volume 16, Issue 10 "A Mathematical Model for Mitigating Centerline Macro Segregation In Continuous Casting Slab" proposed a method to improve the uniform distribution of secondary cooling water on the cross-section of the casting slab, so that the liquid core grows uniformly, that is, the cross-section The solid phase ratio on the center line is basically the same, so as to improve the effect of soft reduction; however, this method will inevitably cause overcooling of the corners of the slab. For crack-sensitive steels such as microalloy steel and peritectic steel, , when the slab passes through the straightening zone or is concentrated in a certain place, if the corner temperature just falls into the third brittle temperature zone, it will inevitably cause corner transverse cracks; It will inevitably extend into a serious corner transverse crack defect, which will lead to the degradation or even scrapping of the whole rolled plate; therefore, the reduction of the cooling strength at the corner will inevitably lead to the uneven growth of the liquid core at the end of solidification

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