公开(公告)号：US20190048431A1

公开(公告)日：2019-02-14

申请号：US16079712

申请日：2017-02-15

Applicant: JFE STEEL CORPORATION

Inventor： Yusuke FUJII ,  Yoshie NAKAI ,  Naoki KIKUCHI ,  Naoya SHIBUTA ,  Shinichi NAGAI ,  Takahiko MAEDA ,  Yuji MIKI

IPC: C21C7/10 ,  C21C7/064 ,  C21C7/072

Abstract: A molten steel refining method includes throwing a powder to molten steel while heating the powder with a flame formed by combustion of a hydrocarbon gas at the leading end of a top blowing lance. The lance height of the top blowing lance (the distance between the static bath surface of the molten steel and the leading end of the lance) is controlled to 1.0 to 7.0 m, and the dynamic pressure P of a jet flow ejected from the top blowing lance calculated from equation (1) below is controlled to 20.0 kPa or more and 100.0 kPa or less. P=ρg× U2/2 . . . (1) wherein P is the dynamic pressure (kPa) of the jet flow at an exit of the top blowing lance, ρg the density (kg/Nm3) of the jet flow, and U the velocity (m/sec) of the jet flow at the exit of the top blowing lance.

公开(公告)号：US20200157645A1

公开(公告)日：2020-05-21

申请号：US16611674

申请日：2018-05-07

Applicant: JFE STEEL CORPORATION

Inventor： Shota AMANO ,  Yukio TAKAHASHI ,  Naoki KIKUCHI ,  Yuji MIKI

IPC: C21C5/32 ,  C21C5/46

Abstract: When the decarburization refining of molten iron is performed by top-blowing oxygen gas from the top blowing lance, the oscillation of molten iron, a bubble burst, and spitting due to the bubble burst are suppressed. A refining method for a converter includes decarburizing molten iron in the converter with a top blowing lance having Laval nozzles disposed at the lower end thereof by blowing oxygen gas on the surface of the molten iron in the converter through the Laval nozzles, in which one or both of an oxygen feeding rate from the top blowing lance and lance height LH are adjusted in such a manner that an oxygen accumulation index S(F) is 40 or less.

公开(公告)号：US20180001377A1

公开(公告)日：2018-01-04

申请号：US15546401

申请日：2016-01-22

Applicant: JFE STEEL CORPORATION

Inventor： Keigo TOISHI ,  Hiroyuki OHNO ,  Norichika ARAMAKI ,  Yuji MIKI

IPC: B22D11/124 ,  B22D11/20

CPC classification number: B22D11/1246 ,  B21B1/466 ,  B21B2201/14 ,  B22D11/1206 ,  B22D11/1282 ,  B22D11/20 ,  B22D11/207 ,  B22D11/225

Abstract: Provided is a continuous casting method of steel that prevents a solidification completion position from being changed even when a drawing speed V of a cast slab is changed. The method includes drawing a cast slab by setting a drawing speed V0 while spraying cooling water to the cast slab at a cooling water spray amount W0 [kg/ton-cast slab]. Then, changing the drawing speed to the speed V1 while spraying cooling water to the cast slab at a cooling water spray amount W1 [kg/ton-cast slab]. The method further includes spraying cooling water to the cast slab at a cooling water spray amount Wt [kg/ton-cast slab] during a period of time t that is obtained by dividing a target length Lt by the drawing speed V0. The water spray amount Wt satisfying either formula (1): Wt W1 under a condition of V1>V0.

公开(公告)号：US20200055113A1

公开(公告)日：2020-02-20

申请号：US16342576

申请日：2017-10-16

Applicant: JFE STEEL CORPORATION

Inventor： Kohei FURUMAI ,  Norichika ARAMAKI ,  Yuji MIKI

IPC: B22D11/059 ,  B22D11/04

Abstract: A continuous casting mold including a water-cooled copper mold having a mold copper plate including an inner wall surface, recessed portions disposed partially or entirely in a region of the inner wall surface of the water-cooled copper mold from at least a position located at a meniscus to a position located 20 mm lower than the meniscus, and material-filled layers disposed in the recessed portions with a metal or nonmetal having a thermal conductivity different from that of the mold copper plate of the water-cooled copper mold. A shape of each of the recessed portions at a surface of the mold copper plate includes a curved surface.

公开(公告)号：US20180363088A1

公开(公告)日：2018-12-20

申请号：US15735678

申请日：2016-08-10

Applicant: JFE STEEL CORPORATION

Inventor： Kenji TSUZUMI ,  Yoshiyasu KAWASAKI ,  Yuji MIKI

IPC: C21D9/46 ,  C22C38/50 ,  C22C38/58 ,  C22C38/32 ,  C22C38/26 ,  C22C38/24 ,  C22C38/22 ,  C22C38/20 ,  B22D11/00 ,  B22D11/124 ,  C21D8/02 ,  C21D6/00 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C23C2/12 ,  C23C2/28 ,  C23C2/40 ,  C23C28/02 ,  B32B15/01

Abstract: A high strength steel sheet having excellent surface quality and formability with a tensile strength of 980 MPa or more and a TS-El balance of 30000 MPa % or more is provided. A high strength steel sheet comprises: a chemical composition containing C: 0.08% to 0.30%, Si: 2.0% or less, Mn: more than 3.0% and 10.0% or less, P: 0.05% or less, S: 0.01% or less, Al: 1.5% or less, Ti: 0.010% to 0.300%, and N: 0.0020% to 0.0100% in a range satisfying 1.1≤(Ti+Mn1/2/400)/(0.01+5N)≤6.0; and a microstructure including a retained austenite phase and a ferrite phase, wherein a ratio γMn/αMn of an average Mn concentration (γMn) of the retained austenite phase to an average Mn concentration (αMn) of the ferrite phase is 1.5 or more.