Method for rare earth treatment of Al2O3 inclusions in full process of cast rolling of refined ultra-low-carbon IF steel

Abstract

The invention discloses a method for rare earth treatment of Al2O3 inclusions in a full process of cast rolling of refined ultra-low-carbon IF steel. At the tail stage of RH refining procedure treatment, rare earth Ce is added, the content of Ce in molten steel reaches 15 ppm, after rare earth alloy is added, re-pressing is carried out for 5 min, after re-pressing, soft blowing is carried out above 8 min, and the average sizes of the Al2O3 inclusions in the thickness directions of a casting blank can be reduced. At the tail stage of RH refining procedure treatment, rare earth Ce is added, thecontent of Ce in the molten steel reaches 15 ppm, Ce is combined with activity O in steel, the lower gibbs free energy is achieved, the concentration and the degree of supersaturation of aluminum andoxygen can be reduced, the capacity of forming the large-size clustered inclusions formed by gathering of single-particle Al2O3 can be reduced, the concentration and the degree of supersaturation of aluminum and oxygen can be reduced, and the capacity of forming the large-size clustered inclusions by the single-particle Al2O3 gathering can be reduced.

Description

technical field [0001] The invention relates to the technical field of steelmaking, in particular to a rare earth treatment refined ultra-low carbon IF steel casting and rolling process Al 2 o 3 Inclusion method. Background technique [0002] According to the application characteristics of automobile outer panels, IF steel is required to have a high degree of cleanliness to ensure that the steel plate has good surface quality and deep drawing performance. In recent years, research institutes and iron and steel enterprises have been devoting themselves to the research on improving the cleanliness of aluminum-deoxidized IF steel by optimizing the traditional smelting process. For the conventional process of BOF-RH-CCM to produce aluminum deoxidized IF steel, in order to avoid destroying the balance of slag and steel, causing the oxygen in the highly oxidizing slag to return to the molten steel, after the aluminum deoxidation at the end of RH refining, LF refining cannot be u...

AI Technical Summary

Problems solved by technology

For the conventional process of BOF-RH-CCM to produce aluminum deoxidized IF steel, in order to avoid destroying the balance of slag and steel, causing the oxygen in the highly oxidizing slag to return to the molten steel, therefore, after the aluminum deoxidation at the end of RH refining, LF refining cannot be used. Also remove Al from steel by calcium treatment and argon stirring 2 o 3 Inclusion

Scholars agree that the large-sized, triangular, chain-like, and dendritic typical Al in aluminum-deoxidized IF steel 2 o 3 The inclusions will be exposed on the surface of the strip during the subsequent rolling and calendering process, forming strip-shaped and pinhole-shaped surface defects. At the same time, the existence of this type of inclusions will also affect the continuity of the structure, causing problems such as stamping cracks in the product

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