MANUFACTURING METHOD OF HIGH CLEANLINESS STEEL

• Main Authors: MIYAMOTO KENICHIRO, GOSHO TAKUMI, SUZUKI HIDEJI
• Format: Patent
• Language: English; Japanese
• Published: 21.09.2017
• 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

PROBLEM TO BE SOLVED: To provide a manufacturing method of a high cleanliness steel capable of reducing the number of alumina inclusions compared to conventional ones, especially reducing the number of alumina inclusions having particle diameter of 20 μm or less.SOLUTION: There is provided a method for continuously casting a molten steel by pouring the same to a tundish 10 after manufacturing the molten steel by primarily purifying, tapping and ladle treating, a slag is modification treated by inputting caustic lime during tapping and adding metal Al and/or flux containing the same to make total of Fe concentration and MnO concentration at 5 mass% or less and molten presence oxygen concentration of the molten steel at 100 to 300 ppm, then conducting a deoxidation treatment by adding the metal Al and stirring for 3 to 10 min, standing the molten steel for 10 min or more and tapping to the tundish 10 having a weir 16 separating a heat retaining part 13 retaining the molten steel and a heat discharging part 15 inputting the molten steel to a mold 14 for continuously casting inside and height at 0.3 to 0.8 times of molten steel depth H.SELECTED DRAWING: Figure 1 【課題】従来よりもアルミナ介在物の個数を低減でき、特に粒径が２０μｍ以下クラスのアルミナ介在物の個数を低減可能な高清浄鋼の製造方法を提供する。【解決手段】一次精錬を行った溶鋼を出鋼し取鍋処理して溶製した後、タンディッシュ１０に注湯して連続鋳造する方法であり、出鋼の際に、生石灰を投入すると共に、金属Ａｌ及び／又はこれを含むフラックスを添加して、スラグを改質処理し、スラグのＴ．Ｆｅ濃度とＭｎＯ濃度の合計を５質量％以下、溶鋼の溶存酸素濃度を１００〜３００ｐｐｍとした後、金属Ａｌを添加し３〜１０分撹拌処理して脱酸処理し、この溶鋼を１０分以上静置して、溶鋼を受け入れる受湯部１３と、溶鋼を連続鋳造する鋳型１４に注入する排湯部１５とに仕切る堰１６が内部に設けられ、その高さを溶鋼深さＨの０．３〜０．８倍としたタンディッシュ１０に注湯する。【選択図】図１