公开(公告)号：US20190040511A1

公开(公告)日：2019-02-07

申请号：US16072904

申请日：2017-01-26

Applicant: JFE STEEL CORPORATION

Inventor： Hiroshi HASEGAWA ,  Yoshimasa FUNAKAWA ,  Hiromi YOSHITOMI ,  Yoichi MAKIMIZU ,  Yoshitsugu SUZUKI ,  Gentaro TAKEDA ,  Yoshikazu SUZUKI ,  Yoshimasa HIMEI

IPC: C23C2/02 ,  C22C38/60 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C21D9/46 ,  C23C2/06 ,  C23C2/26 ,  C23C2/40

Abstract: A high-strength galvanized steel sheet having improved post-work impact resistance, a method for producing the high-strength galvanized steel sheet, and a high-strength member produced using the steel sheet. The high-strength galvanized steel sheet includes a steel sheet having a microstructure including ferrite and carbide-free bainite, martensite and carbide-containing bainite, and retained austenite, the total area fraction of ferrite and carbide-free bainite being 0% to 55%, the total area fraction of martensite and carbide-containing bainite being 45% to 100%, and the area fraction of retained austenite being 0% to 5%. Additionally, a galvanizing layer is disposed on the steel sheet. The density of gaps that cut across the entire thickness of the galvanizing layer in a cross section of the galvanizing layer, which is taken in the thickness direction so as to be perpendicular to the rolling direction, is 10 gaps/mm or more.

公开(公告)号：US20220403480A1

公开(公告)日：2022-12-22

申请号：US17821476

申请日：2022-08-23

Applicant: JFE STEEL CORPORATION

Inventor： Gentaro TAKEDA ,  Yoichi MAKIMIZU ,  Yoshikazu SUZUKI ,  Yoshimasa HIMEI ,  Hideyuki TAKAHASHI

IPC: C21D9/46 ,  C21D1/26 ,  C21D1/74 ,  C21D8/02 ,  C21D9/00 ,  C22C38/02 ,  C23C2/00 ,  C23C2/06 ,  C23C2/26 ,  C23C2/40

Abstract: A continuous hot-dip galvanizing apparatus has a vertical annealing furnace, one or more hearth rolls, a hot-dip galvanizing apparatus, an alloying line, and humidified gas supply ports. When the steel sheet having a Si content of 0.2 mass % or more is conveyed inside the annealing furnace, the humidified gas supply ports positioned in a latter part of the soaking zone supply the humidified gas to the soaking zone and the at least one dry gas supply port supplies the dry gas to the soaking zone. When the steel sheet having a Si content of less than 0.2 mass % is conveyed inside the annealing furnace, the plurality of the humidified gas supply ports do not supply the humidified gas to the soaking zone and the at least one dry gas supply port supplies the dry gas to the soaking zone.

公开(公告)号：US20200299799A1

公开(公告)日：2020-09-24

申请号：US16605305

申请日：2018-02-19

Applicant: JFE STEEL CORPORATION

Inventor： Gentaro TAKEDA ,  Yoichi MAKIMIZU ,  Yoshikazu SUZUKI ,  Yoshimasa HIMEI ,  Hideyuki TAKAHASHI

IPC: C21D9/46 ,  C21D9/00 ,  C21D1/26 ,  C21D1/74 ,  C21D8/02 ,  C23C2/00 ,  C23C2/06 ,  C23C2/26 ,  C23C2/40 ,  C22C38/02

Abstract: Provided is a method for producing a galvannealed steel sheet. When the steel sheet passing through the soaking zone is a type of steel containing 0.2 mass % or more of Si, both dry gas and humidified gas are supplied to the soaking zone, where the humidified gas is supplied only from the humidified gas supply port positioned in a latter part of the soaking zone among a plurality of humidified gas supply ports, where the latter part of the soaking zone is determined considering a sheet passing speed V and a target temperature T on the exit side of the soaking zone.

公开(公告)号：US20190032186A1

公开(公告)日：2019-01-31

申请号：US16071581

申请日：2017-01-20

Applicant: JFE STEEL CORPORATION

Inventor： Takashi UENO ,  Hiroshi HASEGAWA ,  Yoshimasa FUNAKAWA ,  Yoshimasa HIMEI ,  Yoshikazu SUZUKI

IPC: C23C2/06 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/02 ,  C21D8/04

Abstract: High strength steel sheets that have excellent ductility and low-temperature toughness and methods for producing such high strength steel sheets. A high strength steel sheet includes a composition containing, on a mass % basis, C: 0.05% to 0.30%, Si: 0.5% to 2.5%, Mn: 0.5% to 3.5%, P: 0.003% to 0.100%, S: 0.02% or less, Al: 0.010% to 1.5%, and N: 0.01% or less, the balance being Fe and unavoidable impurities, and a steel microstructure including a ferrite phase with an area fraction of 10% to 70%, a hard second phase with an area fraction of 30% to 90%, and a carbide that is at an interface between a ferrite phase and a hard second phase and that has an average equivalent-circle diameter of 200 nm or less.

公开(公告)号：US20180237896A1

公开(公告)日：2018-08-23

申请号：US15753260

申请日：2016-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Gentaro TAKEDA ,  Hideyuki TAKAHASHI ,  Yoichi MAKIMIZU ,  Yoshikazu SUZUKI ,  Yoshimasa HIMEI

IPC: C23C2/02 ,  C23C2/40 ,  C23C2/28 ,  C23C2/06 ,  C21D1/76 ,  C21D9/56 ,  C21D9/573

CPC classification number: C23C2/02 ,  C21D1/76 ,  C21D9/561 ,  C21D9/573 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

Abstract: A method includes: annealing a steel strip by conveying the steel strip through a heating zone, a soaking zone, and a cooling zone in this order inside an annealing furnace; and applying a hot-dip galvanized coating onto the steel strip discharged from the cooling zone. Reducing gas or non-oxidizing gas supplied into the soaking zone includes humidified gas and dry gas. While a width and a sheet passing speed of the steel strip passing through the soaking zone are constant, a variation of pressure in the annealing furnace is suppressed by adjusting a flow rate of the dry gas, and a variation range of an amount of moisture supplied into the soaking zone by the humidified gas is limited to 20% or less.