METHOD FOR PRODUCING LOW CARBON HIGH ALLOY STEEL

• Main Authors: IWANAGA KOJI, SATO RYOICHI, KAMIYAMA TAIICHI, SATO JUN, NAGAO MOTOHIRO, TOBIMATSU HARUKI
• Format: Patent
• Language: English; Japanese
• Published: 09.11.2015
• Subjects: CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; METALLURGY; METALLURGY OF IRON; PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OFWROUGHT-IRON OR STEEL; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS

PROBLEM TO BE SOLVED: To provide a method for producing a low carbon high alloy steel capable of simply and surely obtaining the low carbon high alloy steel by suppressing carbon contamination from an electrode during heating the electrode.SOLUTION: There is provided a method for producing a low carbon high alloy steel containing C:0.02 mass% or less, P:0.01 mass% or less, Ni:8 mass% or more, Cr:10 mass% or more, Mn:20 mass% or more by using refining equipment for conducting electrode heating, including a process of injecting a Ni alloy to an undeoxidized molten steel, a process of decarbonization to make the carbon amount of the molten steel 80 mass ppm or less after a Ni alloy injection process, a process of injecting a Cr alloy and a Mn alloy to a molten steel under the state where a free oxygen concentration is 500 mass ppm or more after the decarbonization process, a process of adding flux to the molten steel so that an average thickness of a slag of a surface of the molten steel becomes 450 mm or more after the decarbonization process and a process of deoxidizing the molten steel so that a free oxygen concentration after the Cr alloy and Mn alloy injection process and the flux addition process becomes 10 mass ppm or less. 【課題】電極加熱時の電極からの炭素混入を抑制して、低炭素高合金鋼を容易かつ確実に得られる低炭素高合金鋼の製造方法を提供することを目的とする。【解決手段】本発明は、電極加熱を行う精錬設備を用い、Ｃ：０．０２質量％以下、Ｐ：０．０１質量％以下、Ｎｉ：８質量％以上、Ｃｒ：１０質量％以上、Ｍｎ：２０質量％以上を含む低炭素高合金鋼の製造方法であって、未脱酸溶鋼にＮｉ合金を投入する工程と、Ｎｉ合金投入工程後に溶鋼の炭素量が８０質量ｐｐｍ以下となるように脱炭する工程と、脱炭工程後に溶鋼のフリー酸素濃度が５００質量ｐｐｍ以上の状態で溶鋼にＣｒ合金及びＭｎ合金を投入する工程と、脱炭工程後に溶鋼表面のスラグの平均厚さが４５０ｍｍ以上になるように溶鋼へフラックスを添加する工程と、Ｃｒ合金及びＭｎ合金投入工程並びにフラックス添加工程の後にフリー酸素濃度が１０質量ｐｐｍ以下となるように溶鋼を脱酸する工程とを備える。【選択図】図１