DUPLEX STAINLESS STEEL MATERIAL
    3.
    发明公开

    公开(公告)号:EP4414471A1

    公开(公告)日:2024-08-14

    申请号:EP22878499.7

    申请日:2022-10-04

    摘要: A duplex stainless steel material that has excellent general corrosion resistance and pitting resistance in a supercritical corrosive environment in which SOx gas and O2 gas are contained in a supercritical CO2 gas is provided. A duplex stainless steel material of the present disclosure has the chemical composition described in the description, and in the duplex stainless steel material, on a precondition that the content of each element is within a range described in the description, Fn defined by Formula (1) is 44.0 or more, and a total number per 1 mm2 of Mn sulfides having an equivalent circular diameter of 1.0 µm or more and Ca sulfides having an equivalent circular diameter of 2.0 µm or more is 0.50 /mm2 or less. Fn=Cr+3.3Mo+0.5W+16N+2Ni+Cu+2Co+10Sn
    Where, the content in mass% of a corresponding element is substituted for each symbol of an element in Formula (1).

    METHOD FOR DEOXIDIZING/REFINING MOLTEN STEEL, METHOD FOR PRODUCING STEEL MATERIAL, AND STEEL MATERIAL THEREOF

    公开(公告)号:EP4361293A1

    公开(公告)日:2024-05-01

    申请号:EP22852803.0

    申请日:2022-07-14

    IPC分类号: C21C7/10 C21C7/04 C21C7/06

    摘要: Provided is a technique that improves the yield of Al to be added without increasing a vacuum refining cost. Also provided is a method of producing a steel material that varies little in the ingredient amount of Al. In a method for deoxidation refining of molten steel using a vacuum refining equipment, an Al-containing substance is added to molten steel inside a vacuum vessel, and deoxidation refining of the molten steel is performed in such a manner that temperature changes ΔT1 and ΔT2 of the molten steel during Al deoxidation meet Formula (1). It is preferable that the Al content in the Al-containing substance added be 30 to 80 mass%. Performing this method for deoxidation refining of molten steel as a deoxidation step can produce a steel material in which the range of the Al concentration in steel after the deoxidation step is 0.02 mass% or less. ΔT1 + ΔT2

    MOLTEN STEEL DENITRIFICATION METHOD, SIMULTANEOUS DENITRIFICATION AND DESULFURIZATION TREATMENT METHOD, AND STEEL PRODUCTION METHOD

    公开(公告)号:EP4353845A1

    公开(公告)日:2024-04-17

    申请号:EP22819992.3

    申请日:2022-05-12

    IPC分类号: C21C7/00 C21C7/072 C21C7/10

    摘要: Proposed is a method in which a denitrification treatment that allows an extremely low nitrogen concentration range to be stably and quickly reached is performed, or further this denitrification treatment and a desulfurization treatment are performed within a single treatment, such that denitrification, or denitrification and desulfurization, of molten steel can be efficiently performed. This molten steel denitrification method is a molten steel denitrification treatment in which CaO-and-Al2O3-containing slag 4 is formed on top of molten steel 3 charged in a vessel 1 and an oxygen-containing gas is blown from above the slag, while the slag and the molten steel are brought into contact with each other to remove nitrogen in the molten steel. This method is characterized in that an Al concentration in the molten steel is kept at or higher than a value determined by Formula (1) according to a stirring power density, and that the oxygen-containing gas is blown such that a ratio between a thickness Ls0 of the slag and a depth Ls of a depression in the slag resulting from blowing of the oxygen-containing gas meets Ls/Ls0 ≥ 1: Al concentration (mass%) in molten steel = -0.072 × ln (stirring power density (W/t)) + 0.5822 ···· (1)