HIGHLY CLEAN EXTRA-LOW SULFUR STEEL AND ITS PRODUCTION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a highly clean extra-low sulfur steel and its production method by which the generation of MnS base inclusion, etc., is prevented. SOLUTION: The concentration of [S] in the steel is made to be <=10 mass ppm and [Ca] concentration in the steel is made to be 0.1-8 mass ppm by adding metallic Ca-containing material and CaO-containing material into molten steel in the interval after completing a converter-treatment to the casting.