Slab narrow-face inwards-convex curved-surface crystallizer and design method thereof

Abstract

The invention provides a slab narrow-face inwards-convex curved-surface crystallizer and a design method thereof and belongs to the field of continuous steel casting. The narrow-face copper plate of the crystallizer is of a structure wide in upper opening and narrow in lower opening, and the upper-opening copper plate and the lower-opening copper plate are equal in thickness. The inner surface of the narrow-face copper plate is of an inwards-convex curved-surface structure and is composed of a middle regional convex curved surface and an edge regional convex curved surface. The slab narrow-face inwards-convex curved-surface crystallizer can fully compensate shrinkage of a slab shell in the crystallizer, effectively inhabit distribution of casting slag films and air gaps in the areas nearby corners of the slab shell, accordingly achieve quick cooling of corners of the cast slab, refine initially-set structure crystal grains of the corners of the cast slab, disperse carbonitride precipitated in the grains and grain boundaries and fundamentally inhibit production of cracks at the corners of the micro-alloyed steel continuously-cast slab. By using the slab narrow-face inwards-convex curved-surface crystallizer, 'hot spots' in the areas nearby the corners of the wide face and the narrow face of the slab shell can be effectively eliminated, and even growth of the slab shell in the crystallizer is achieved.

Description

technical field [0001] The invention belongs to the field of steel continuous casting, and in particular relates to a slab narrow surface convex curved crystallizer and a design method thereof. Background technique [0002] The microalloying technology of steel developed rapidly in the 1970s. Adding microalloying elements such as Ti, Nb, B, and V to steel can greatly improve the strength and plasticity of steel, which has been widely used in modern steel production. However, adding microalloying elements to steel greatly increases the crack sensitivity of the slab. Improvement, continuous casting production of this type of steel slabs often have corner transverse crack defects; it has been clarified that the main reason for the frequent occurrence of corner transverse cracks in micro-alloy steel continuous casting slabs is: in the existing continuous casting process and cooling In this mode, the microalloying elements in the steel are easily combined with C, N and other ele...

AI Technical Summary

Problems solved by technology

However, this taper design does not take into account the fact that the corners of the billet shell shrink more than the central area of ​​the narrow face during the solidification process of the actual shell. Effectively eliminate the concentrated distribution of mold slag film and air gap in the corner area of ​​the billet shell;

[0005] The patent of invention with the publication number CN104117641A discloses a method and device for obtaining the continuous taper of a segmented reference parabola of a crystallizer, which realizes a better contact between the casting slab and the copper plate of the crystallizer; however, the continuous tapered crystallizer designed by this method is also The fact that the corner shrinkage is larger than the central area of ​​the narrow face during the solidification process of the actual billet shell is not considered;

[0006] The articles titled "Study on Taper of Copper Plate in Slab Mold" and "Study on Taper of Copper Plate in Baosteel Slab Mold" studied the shrinkage law of the slab shell along the center direction of the width and narrow face of the mold, and proposed the setting of the wide face of the mold. Small taper and narrow face set different taper viewpoints according to different casting speed conditions; this study did not change the taper structure of the narrow face of the crystallizer, but only adjusted the taper size based on the original linear narrow face mold, so it still cannot cater to the actual billet shell Dynamic solidification shrinkage characteristics along the height direction;

[0007] The invention patent with the publication number CN1559722A discloses a technology for online control of the taper of the narrow surface of the slab crystallizer based on the ratio of heat flow between the narrow surface and the wide surface of the mold; this technology is only based on the existing linear mold copper plate structure. The size of the face taper also cannot overcome the problem that the traditional crystallizer copper plate cannot meet the dynamic solidification and shrinkage characteristics of the billet shell;

[0008] The invention patent with the publication number CN102328037A discloses a self-tapered slab chamfering crystallizer which effectively eliminates the transverse cracks at the corners of the slab; The taper design of the chamfered surface is realized, and the taper in the middle area of ​​the copper plate of the narrow mold is appropriately increased linearly, which is equivalent to the overall adjustment of the taper of the traditional straight-line narrow surface in terms of use effect, and it is also unable to overcome the taper of the narrow mold surface Insufficient compensation for billet shell shrinkage in the upper part and excessive compensation in the lower part;

[0009] The invention patent with the application number 201310356316.X discloses a method for designing the taper of the slab crystallizer based on the dynamic shrinkage characteristics of the billet shell and the distribution behavior of the mold slag film and the air gap. Through this taper, the copper plate can effectively cater to the solidification and shrinkage characteristics of the billet shell. And realize the rapid cooling of the corner of the slab; but the taper of the mold designed by this method needs to introduce a wedge-shaped structure at the corner of the wide-faced copper plate, which hinders the realization of the online width adjustment function of the mold, and is only applicable to the single-section slab continuous casting production;

Images