Control method for improving internal defects of high-carbon chromium bearing steel bloom

Abstract

The invention discloses a control method for improving internal defects of a high-carbon chromium bearing steel bloom. The control method comprises the steps that molten steel is cast into a large-chamfer bloom with a liquid core, continuous casting parameters are controlled, and a soft reduction process is carried out on the large-chamfer bloom with the liquid core. According to the method, the included angle between the corner of the continuous casting billet and the wide surface of the casting billet is controlled to be 30-40 degrees, and the length of the bevel edge is controlled to be 45-60 mm; the superheat degree of molten steel in the tundish is controlled to be 15-30 DEG C, and the casting speed is controlled to be 0.70-0.85 m / min; and dynamic soft reduction and static soft reduction are respectively carried out on the large-chamfer continuous casting billet with the liquid core. The internal defects of reduction cracks, center segregation and the like of the high-carbon chromium bearing steel bloom are overcome; the high-carbon chromium bearing steel bloom is subjected to macroscopic examination, the macroscopic examination comprises 0-0.5 grade of center porosity, 0.5-1.0 grade of center segregation, 0-0.5 grade of shrinkage cavity, 0-0.5 grade of middle cracks, 0-0.5 grade of center cracks and 55-68% of isometric crystal ratio; and the carbon segregation index of the center of the continuous casting billet is 0.95-1.06.

Description

technical field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a control method for improving internal defects of high-carbon chromium bearing steel blooms. Background technique

[0002] With the development and progress of continuous casting technology and the improvement of product quality requirements, the section size of billets tends to be larger. However, due to the inherent properties of solidification of various elements of molten steel, especially for high-carbon steel types, internal defects such as central segregation, porosity, and intermediate cracks are difficult to control, which has a great impact on product quality.

[0003] In order to improve the internal defects of the continuous casting slab, the electromagnetic stirring technology, the low superheat pouring technology of the heating tundish, and the solidification end depression technology have been successively developed and successfully applied. The int...

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