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1. (WO2018043453) THIN STEEL SHEET AND PROCESS FOR PRODUCING SAME

Pub. No.:    WO/2018/043453    International Application No.:    PCT/JP2017/030846
Publication Date: Fri Mar 09 00:59:59 CET 2018 International Filing Date: Wed Aug 30 01:59:59 CEST 2017
IPC: C22C 38/00
C21D 9/46
C22C 18/00
C22C 18/04
C22C 38/06
C22C 38/60
Applicants: JFE STEEL CORPORATION
JFEスチール株式会社
Inventors: KOHSAKA Noriaki
▲高▼坂 典晃
SUZUKI Yoshikazu
鈴木 克一
KIKUCHI Takeo
菊池 健夫
HIMEI Yoshimasa
姫井 善正
Title: THIN STEEL SHEET AND PROCESS FOR PRODUCING SAME
Abstract:
Provided are: a thin steel sheet having a tensile strength of 950 MPa or higher and satisfactory toughness; and a process for producing the thin steel sheet. The thin steel sheet is characterized by having a specific composition and a metallographic structure that comprises up to 30% (including 0%) by area ferrite, at least 70% (including 100%) by area tempered martensite, and up to 4.5% (including 0%) by area retained austenite, the tempered martensite grains containing iron-based carbide grains precipitated therein, wherein 10% of the iron-based carbide grains ranging from the largest in grain diameter have an average aspect ratio of 3.5 or higher.