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.

公开(公告)号：US20240044822A1

公开(公告)日：2024-02-08

申请号：US18256096

申请日：2021-09-06

Applicant: JFE STEEL CORPORATION

Inventor： Tomoharu ISHIDA ,  Seiya SUGAWARA ,  Kenji TSUZUMI

IPC: G01N23/2251 ,  G01N23/2252 ,  G01N33/2028

CPC classification number: G01N23/2251 ,  G01N23/2252 ,  G01N33/2028 ,  G01N2223/418 ,  G01N2223/624

Abstract: A method of evaluating central segregation in steel with excellent correlation with HIC susceptibility is provided. A method of evaluating central segregation in steel includes: taking a sample from a steel, the sample having a cross section including a central segregation area; measuring an area ratio of an inclusion containing a segregation metal element in a region to be measured including the central segregation area in the cross section; and evaluating central segregation in the steel based on the area ratio measured.