METHOD OF SMELLING STEEL INTO HIGH CLEANED STEEL

• Main Authors: MIYAMOTO KENICHIRO, WATANABE EIJI, NAKAE TAICHI, OHARA NAOYA
• Format: Patent
• Language: English; Japanese
• Published: 23.01.2020
• Subjects: CASTING; CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES; CHEMISTRY; METALLURGY; METALLURGY OF IRON; PERFORMING OPERATIONS; POWDER METALLURGY; PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OFWROUGHT-IRON OR STEEL; TRANSPORTING; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS

To provide a method of smelling steel into high cleaned steel capable of providing cast high cleaned steel by smelling in which alumina inclusions is reduced rather than prior art.SOLUTION: When a vacuum degassing treatment is conducted by immersing immersion pipes 12 and 13 of an RH vacuum degassing device 10 into a molten steel in a ladle 14 in which dissolved oxygen concentration is 40 ppm or less by adding metal Al to the molten steel which has been subjected to primary refining, and jetting inert gas thereinto, and then circulating the molten steel between a vacuum tank 11 and the ladle 14, a degassing treatment under low pressure vacuum atmosphere of 1.3 kPa or less for 15 to 45 min. is conducted in first half of the vacuum degassing treatment, and a degassing treatment under high pressure vacuum atmosphere of 20 to 40 kPa for 5 to 15 min. in second half, then the vacuum degassing treated molten steel is poured into a tundish 15 in which a dam 20 partitioning a molten metal receiving section 17 and a metal discharging section 19 is arranged inside at a state upwardly projecting from a bottom, and height of the dam 20 is set at 0.3 to 0.8 times of molten steel depth.SELECTED DRAWING: Figure 1 【課題】従来の技術よりもアルミナ介在物を低減した高清浄鋼を溶製して鋳造することが可能な高清浄鋼の溶製方法を提供する。【解決手段】一次精錬を行った溶鋼に金属Ａｌを添加し溶存酸素濃度を４０ｐｐｍ以下とした取鍋１４内の溶鋼に、ＲＨ真空脱ガス装置１０の浸漬管１２、１３を浸漬して不活性ガスを吹き込み、真空槽１１と取鍋１４との間で溶鋼を環流させる真空脱ガス処理を行う際に、真空脱ガス処理の前半に、１．３ｋＰａ以下の低圧真空雰囲気で１５〜４５分間の脱ガス処理を行い、後半に、２０〜４０ｋＰａの高圧真空雰囲気で５〜１５分間の脱ガス処理を行った後、受湯部１７と排湯部１９とに仕切る堰２０が内部に、底部から上方に向けて突出させた状態で設けられ、堰２０の高さを溶鋼深さの０．３〜０．８倍としたタンディッシュ１５に、真空脱ガス処理した溶鋼を注湯する。【選択図】図１