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1. (WO2017038070) HIGH STRENGTH THIN STEEL SHEET AND METHOD FOR MANUFACTURING SAME

Pub. No.:    WO/2017/038070    International Application No.:    PCT/JP2016/003902
Publication Date: Fri Mar 10 00:59:59 CET 2017 International Filing Date: Sat Aug 27 01:59:59 CEST 2016
IPC: C22C 38/00
C21D 9/46
C22C 38/06
C22C 38/58
Applicants: JFE STEEL CORPORATION
JFEスチール株式会社
Inventors: SHIIMORI, Fusae
椎森 芳恵
KAWASAKI, Yoshiyasu
川崎 由康
KANEKO, Shinjiro
金子 真次郎
YOKOTA, Takeshi
横田 毅
SETO, Kazuhiro
瀬戸 一洋
TANAKA, Takaaki
田中 孝明
TOJI, Yuki
田路 勇樹
Title: HIGH STRENGTH THIN STEEL SHEET AND METHOD FOR MANUFACTURING SAME
Abstract:
Provided is a high strength thin steel sheet having both excellent tensile strength and elongation, and also having low elongation anisotropy. This high strength thin steel sheet has a predetermined composition, and has a structure in which the total area ratio of ferrite, tempered bainitic ferrite and bainitic ferrite is 40-70%, the area ratio of martensite is 5-30%, the area ratio of retained austenite 10-35%, the average equivalent circular diameter of martensite and retained austenite (second phase) grains is 2.0 µm or less, the area ratio of grains having an equivalent circular diameter of 2.0 µm or greater in the second phase is 10% or less, and the average short diameter of grains in the second phase is 0.40 µm or less.