| 摘要 |
PURPOSE:To easily and stably manufacture a low-N, high-Cr, and high-Ni steel in high yield, by regulating Cr concentration by calculating it from a specific equation according to N concentration in ferrochrome to be added in the final stage at the time of melting a Cr- and Ni-containing steel. CONSTITUTION:The Cr- and Ni-containing steel is melted under atmospheric pressure in the primary stage. Subsequently, the above molten steel is subjected to decarburizing refining under reduced pressure in the secondary stage. Further, in the tertiary stage, ferrochrome is added to the molten steel after the above refining to regulate Cr content, so that low-N, high-Cr, and high-Ni steel containing 15-35wt.% Cr and be obtained. In the manufacturing process of the above steel, the Cr concentration of the high-Cr and high-Ni steel in the primary stage is previously calculated by an equation [N]f=[N]d.W/(W+WFeCr)+[N]FeCr.WFeCr/(-W+WFeCr) (where [N]f and [N]d represent N concentrations at the conclusion of the secondary and tertiary stages, respectively, W means the amount of molten metal in the primary stage, WFeCr means the additive quantity of ferrochrome, and [N]FeCr means N concentration in ferrochrome) and regulated so that N concentration at the conclusion of the above tertiary stage is <=100ppm by weight, and decarburization is carried out until <=0.3wt.% C is reached.
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