Method for reducing center segregation of small high-carbon steel billet

Abstract

The invention relates to the technical field of metallurgy, and discloses a method for reducing center segregation of a small high-carbon steel billet. The equiaxial grain proportion of the heart of acasting blank of the small high-carbon steel billet is increased with electromagnetic stirring and crystallizer wire feeding technologies in the continuous casting process, the center segregation degree of the small high-carbon steel billet is reduced, after implementation, the equiaxial grain area of the small high-carbon steel billet is increased from 31%-37% to 49%-55%, the center segregationcoefficient is reduced from 1.12-1.23 to 1.03-1.13, and the segregation degree inside the casting blank is remarkably reduced.

Description

technical field [0001] The invention relates to the field of metallurgy technology, in particular to a method for reducing central segregation of a high-carbon steel billet, which is used to increase the proportion of equiaxed crystals at the core of a high-carbon steel billet and reduce central segregation of a high-carbon steel billet degree. Background technique [0002] Hot-rolled high-carbon steel wire rod is the main raw material for producing high-strength, low-relaxation prestressed steel wire or steel strand. These products are mainly used in high-strength projects such as long-span bridges and high-rise buildings. In the production process of high-carbon steel wire rod, defect structures such as secondary cementite and martensite in the center of the wire rod are often generated. The denaturation ability of these defect structures is different from that of the matrix. In the subsequent drawing process It will induce the pen-shaped fracture of the wire rod, which r...

AI Technical Summary

Problems solved by technology

The problem with this method of improving segregation is: after the slab leaves the mold, most of the slab is still in a liquid state except for a very thin layer of shell solidification, and the core of the slab still carries a large amount of heat. , the heat will cause the primary dendrites broken during the stirring process of the crystallizer to melt again, reduce the number of solid cores used to generate equiaxed grains in the slab, and weaken the effect of the electromagnetic stirring of the mold to improve the segregation of the slab center

Premature stirring is equivalent to the electromagnetic stirring of the mold, which cannot avoid the enrichment of solute elements caused by the secondary melting of equiaxed grains in the slab, and has a limited effect on improving the center segregation inside the slab

And if the stirring is too late, the molten steel has solidified, and the stirring has lost its meaning.

The actual situation is that during the cooling and solidification process of the slab in the secondary cooling section, due to the existence of uncertain factors such as the mold slag film on the surface of the slab, the thickness and coverage of the oxide scale on the surface of the slab, the cooling medium and the ambient temperature, the casting The solidification process of the slab is extremely difficult to control, resulting in uncertain changes in the position of the solidification end, especially for continuous casting slabs with small cross-sections. These uncertain factors have a greater impact on the position of the solidification end. Greatly weakens the effect of terminal electromagnetic stirring to eliminate segregation

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