METHOD FOR SMELTING STEEL INTO HIGHLY 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 for smelting steel into highly cleaned steel capable of smelting steel into highly cleaned steel by reducing alumina inclusion when compared to prior art and casting the same.SOLUTION: When a vacuum degassing treatment is conducted, in which immersion pipes 12 and 13 of an RH vacuum degasser 10 is immersed into a molten steel in a ladle 14 with dissolved oxygen concentration of 40 ppm or less by adding metal Al to the molten steel which has been subjected to primary refining, and inert gas is jetted, and the molten steel is circulated between the vacuum tank 11 and the ladle 14, a dam 17 provided with a molten steel flow channel 21 communicating a molten metal receiving part 18 and a molten metal discharging part 19 is arranged inside after conducting a degassing treatment for 15 to 45 min. under low pressure vacuum atmosphere at 1.3 kPa or less in first half of the vacuum degassing treatment, and the degassing treatment for 5 to 15 min. under high pressure vacuum atmosphere at 20 to 40 kPa in second half, the molten steel is introduced into a tundish 15 with height position of an aperture 23 in the molten steel receiving part 18 side of the molten steel flow channel 21 from a bottom 26 of the molten steel receiving part 18 set at 0.2 times or less of molten steel depth of the molten steel receiving part 18, and induction heated in a molten steel flow channel 21.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１８と排湯部１９を連通する溶鋼流路２１を形成した堰１７が内部に設けられ、溶鋼流路２１の受湯部１８側の開口部２３の受湯部１８の底面２６からの高さ位置を、受湯部１８の溶鋼深さの０．２倍以下としたタンディッシュ１５に注湯し、溶鋼流路２１で誘導加熱する。【選択図】図１