公开(公告)号：US20240287632A1

公开(公告)日：2024-08-29

申请号：US18571637

申请日：2022-06-14

Applicant: JFE STEEL CORPORATION

Inventor： Hidemitsu NEGISHI ,  Takeshi MURAI ,  Keisuke MIZOBATA

IPC: C21C5/52 ,  C21C7/00 ,  C21C7/06 ,  C21C7/068 ,  C21C7/10

CPC classification number: C21C5/5229 ,  C21C7/0006 ,  C21C7/06 ,  C21C7/068 ,  C21C7/10 ,  C21C2300/08

Abstract: A treatment method of molten steel capable of preventing metal components in molten steel from being reoxidized by reacting with oxides in molten slag, inhibiting occurrence of inclusions, and reducing nitrogen in the molten steel. The treatment method of molten steel in which a potential difference is applied between the molten steel and the molten slag by using a direct-current power supply and through two electrodes which are a negative electrode being an electrode in contact with the molten steel and a positive electrode being another electrode in contact with only the molten slag is characterized by including: a deoxidation step of deoxidizing the molten steel by adding a deoxidizing agent to the molten steel; and a step of applying the potential difference after the deoxidation step. Also, a steel production method by which the obtained molten steel is cast after components thereof are adjusted.

公开(公告)号：US20230142051A1

公开(公告)日：2023-05-11

申请号：US17914528

申请日：2021-03-24

Applicant: JFE STEEL CORPORATION

Inventor： Keisuke MIZOBATA ,  Akifumi HARADA ,  Yoshie NAKAI ,  Rei YAMADA

IPC: C21C7/068 ,  C21C7/10 ,  C21C7/00

CPC classification number: C21C7/068 ,  C21C7/10 ,  C21C7/0068 ,  C21C2300/06 ,  C21C7/0075

Abstract: A decarburization refining method for molten steel under reduced pressure. The method includes an oxygen-blowing decarburization and a rimmed decarburization. Using operation data taken at a time when oxygen-blowing decarburization is started and a time when oxygen-blowing decarburization is ended, an amount of carbon removed while the oxygen-blowing decarburization is performed is estimated. Based on the estimated amount of carbon removed, a carbon concentration in molten steel at a time when the rimmed decarburization is started is estimated. Using the estimated value as the carbon concentration in molten steel at the time when the rimmed decarburization is started, a change over time in the carbon concentration in molten steel while the rimmed decarburization is performed is calculated. Based on the calculated change over time in the carbon concentration in molten steel while the rimmed decarburization is performed, a determination is made about a time when the rimmed decarburization is ended.

公开(公告)号：US20230340629A1

公开(公告)日：2023-10-26

申请号：US18010103

申请日：2021-06-16

Applicant: JFE STEEL CORPORATION

Inventor： Keisuke MIZOBATA ,  Akifumi HARADA ,  Yoshie NAKAI ,  Takeshi MURAI ,  Hidemitsu NEGISHI

IPC: C21C7/10

CPC classification number: C21C7/10

Abstract: A molten steel refining method increases a circulating rate using an RH vacuum degassing apparatus. An immersion depth of an immersion tube into molten steel inside a vacuum tank or a circulating gas flow rate is determined such that a stirring power energy density ε for the molten steel meets the following formulae: ε = [371GT × ln{ 1 + (ρLgH0/P)}]/Wv, Wv = (π·Dv2/4) × H0 × ρL/1000, H0 = hv + L - hG, hv = (P0 - P)/(ρLg) + 1 -L, 1.35 × 105 × DU/WV

公开(公告)号：US20230083264A1

公开(公告)日：2023-03-16

申请号：US17797909

申请日：2021-02-02

Applicant: JFE STEEL CORPORATION

Inventor： Shuji KUYAMA ,  Tomoyoshi OGASAHARA ,  Yoshie NAKAI ,  Keisuke MIZOBATA ,  Tomoharu ISHIDA ,  Masamichi KIKUCHI

IPC: C21C7/068 ,  G01N33/2025 ,  F27D7/06 ,  C21C7/10 ,  C21C7/072

Abstract: A decarburization end point determination method includes: estimating the carbon concentration and oxygen concentration of the molten steel and carbon dioxide gas concentration of exhaust gas in the vacuum chamber by using measurement values of the carbon concentration and the oxygen concentration of the molten steel, a measurement value of internal pressure of the vacuum chamber, and a model formula; correcting a parameter included in the model formula to reduce at least one of a difference between an estimate value and a measurement value of the oxygen concentration and a difference between an estimate value and a measurement value of the carbon dioxide gas concentration of the exhaust gas; estimating the carbon concentration of the molten steel by using the model formula in which the parameter is corrected; and determining timing when an estimate value reaches a target value as the completion time point of the vacuum decarburization treatment.