公开(公告)号：US20230082367A1

公开(公告)日：2023-03-16

申请号：US17760362

申请日：2020-11-19

Applicant: JFE STEEL CORPORATION

Inventor： Shunsuke YAMAMOTO ,  Shotaro TERASHIMA ,  Yuki TAKEDA ,  Michitaka SAKURAI ,  Katsuya HOSHINO ,  Yoshiyasu KAWASAKI

IPC: C21D9/46 ,  C22C38/02 ,  C22C38/38 ,  C21D1/26 ,  C22C38/12 ,  C22C38/06 ,  C22C38/00 ,  C22C38/28 ,  C22C38/32 ,  C22C38/16 ,  C21D6/00 ,  C22C38/08 ,  C23C2/02 ,  C23C2/28 ,  C23C2/40

Abstract: To obtain a high-strength hot-dip galvanized steel sheet having excellent surface appearance even in the case where a steel strip containing Mn at a predetermined ratio or more to Si is subjected to hot-dip galvanizing treatment, a method of producing a hot-dip galvanized steel sheet using a continuous hot-dip galvanizing apparatus comprises: subjecting a steel strip to annealing, by conveying it in an annealing furnace; and subjecting the steel strip discharged from a cooling zone to hot-dip galvanizing using a hot-dip galvanizing line, to obtain a hot-dip galvanized steel sheet. The steel strip has a chemical composition containing, in mass %, Mn: 1.7% or more and 3.5% or less and Si: 0.2% or more and 1.05% or less and satisfying [Si]/[Mn]≤0.30. The chemical composition, a dew point of an atmosphere in the soaking zone, and a delivery temperature of the heating zone satisfy Formula (1).

公开(公告)号：US20220186339A1

公开(公告)日：2022-06-16

申请号：US17432218

申请日：2020-01-17

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi TAKASHIMA ,  Minoru TANAKA ,  Yoshie OBATA ,  Michitaka SAKURAI

IPC: C21D9/48 ,  C21D8/04 ,  C21D6/00 ,  C22C38/60 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/58 ,  C22C38/00 ,  C22C38/02 ,  B32B15/01

Abstract: Provided is a hot-pressed member that combines both high strength of 1850 MPa or more in TS and excellent delayed fracture resistance. A hot-pressed member comprises: a predetermined chemical composition; a microstructure in which a prior austenite average grain size is 8 μm or less, a volume fraction of martensite is 95% or more, and a volume fraction of granular carbide of 0.1 μm or more in grain size is 0.10% to 4.0%; a Ni diffusion region of 2.0 μm or more in a depth direction in a surface layer; and a tensile strength of 1850 MPa or more.

公开(公告)号：US20180237880A1

公开(公告)日：2018-08-23

申请号：US15554591

申请日：2016-01-14

Applicant: JFE STEEL CORPORATION

Inventor： Noriaki KOHSAKA ,  Yoshimasa FUNAKAWA ,  Michitaka SAKURAI ,  Yoshikazu SUZUKI

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/60 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C23C2/40 ,  C23C2/28 ,  C23C2/06 ,  C22C18/04

CPC classification number: C21D9/46 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C22C18/00 ,  C22C18/04 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/60 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

Abstract: A high-strength steel sheet having a composition containing C: 0.09% to 0.17%, Si: 0.6% to 1.7%, Mn: 3.5% or less, P: 0.03% or less, S: 0.005% or less, Al: 0.08% or less, N: 0.006% or less, Ti: 0.05% or less, and B: 0.0002% to 0.0030% on a mass basis, the remainder being Fe and inevitable impurities. The steel sheet also has a microstructure containing less than 20% (including 0%) of a ferrite phase, 75% or more (including 100%) of a tempered martensite phase, 10% or less (including 0%) of an untempered martensite phase, and less than 5% (including 0%) of a retained austenite phase in terms of area fraction. The tempered martensite phase has a Vickers hardness of 280 to 340 and a tensile strength of 950 MPa to 1,120 MPa.