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1. (WO2018025674) HIGH-STRENGTH STEEL PLATE AND MANUFACTURING METHOD THEREOF

Pub. No.:    WO/2018/025674    International Application No.:    PCT/JP2017/026557
Publication Date: Fri Feb 09 00:59:59 CET 2018 International Filing Date: Sat Jul 22 01:59:59 CEST 2017
IPC: C22C 38/00
C21D 1/18
C21D 9/46
C22C 38/06
Applicants: KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.)
株式会社神戸製鋼所
Inventors: KAKIUCHI, Elijah
柿内 エライジャ
MURAKAMI, Toshio
村上 俊夫
OTANI, Shigeo
大谷 茂生
FUTAMURA, Yuichi
二村 裕一
MURATA, Tadao
村田 忠夫
Title: HIGH-STRENGTH STEEL PLATE AND MANUFACTURING METHOD THEREOF
Abstract:
This high-strength steel plate contains C: 0.15-0.35 mass%, total of Si and Al: 0.5-3.0 mass%, Mn: 1.0-4.0 mass%, P: 0.05 mass% or less and S: 0.01 mass% or less, the remainder being Fe and unavoidable impurities. In the steel composition, the ferrite fraction is 5% or less, the total fraction of tempered martensite and tempered bainite is 60% or higher, the amount of retained austenite is 10% or greater, the average size of MA is 1.0 μm or less, the average size of the retained austenite is 1.0 μm or less, the retained austenite with a size of greater than or equal to 1.5 μm is at least 2% of the total amount of retained austenite, and the scattering intensity in small-angle X-ray scattering with a q-value of 1 nm-1 is less than or equal to 1.0 cm-1.