Control method for ultra-clean rare earth steel and inclusion reforming

摘要

A method for controlling ultra-clean rare-earth steel and inclusions, wherein the steel contains 10-200 ppm of rare-earth elements, and 50% or more of inclusions in the steel have an average equivalent diameter (D mean ) of 1-5 μm, spherical or nearly spherical or granular, diffusion distributed RE-oxygen-sulfide, wherein the method modifies at least 80%, preferably at least 90%, of Al 2 O 3 inclusions in the steel to RE-oxygen-sulfide, the composition being the same Compared with steel types that do not contain one rare earth, the total amount of inclusions in steel is reduced by 18% or more , and the possibility of rupture due to Al 2 O 3 inclusions among conventional high-purity steels is reduced, thereby improving mechanical and mechanical performance such as fatigue life of steel. It significantly improves and realizes precise control of the type, distribution and size of inclusion modification in the steel, and is applied to research and production of more diverse high-performance steels.