Title:
LOW YIELD RATIO STEEL SHEET AND METHOD FOR PRODUCING THE SAME
Document Type and Number:
Japanese Patent JP2017078212
Kind Code:
A
Abstract:
PROBLEM TO BE SOLVED: To provide a low yield ratio steel sheet having small variation in mechanical properties and excellent low-temperature toughness and a method for efficiently producing the same.SOLUTION: A low yield ratio steel sheet has a chemical composition comprising, in mass%, C: 0.03-0.10%, Si: 0.05-0.5%, Mn: 0.9-2.0%, P: 0.020% or less, S: 0.010% or less, Nb: 0.005-0.05%, Ti: 0.005-0.025%, sol.Al: 0.005-0.090%, N: 0.001-0.010%, Cu: 0-0.50%, Ni: 0-0.50%, Cr: 0-0.20%, Mo: 0-0.20%, V: 0-0.06%, B: 0-0.002%, Ca: 0-0.005%, Mg: 0-0.005%, with the balance being Fe and impurities, satisfying [0.10≤Cu+Ni+Cr+Mo≤1.0], the low yield ratio steel sheet having a metallographic structure in which: in a ferrite grain size distribution at a position of 1/4 of the sheet thickness, a percentage of the number of ferrite less than 10 μm is 70-85%, a percentage of the number of ferrite 10-20 μm is 13.5-30%, a percentage of the number of ferrite more than 20 μm is 1.5% or less, and a maximum ferrite grain size is 22 μm or less.SELECTED DRAWING: None
Inventors:
INOKARI GENKI
KAMO TAKAHIRO
NAKAMURA HIROSHI
TACHIBANA HISAYOSHI
YUASA TAKAYUKI
ISOBE GEN
KUBO SATOSHI
KAMO TAKAHIRO
NAKAMURA HIROSHI
TACHIBANA HISAYOSHI
YUASA TAKAYUKI
ISOBE GEN
KUBO SATOSHI
Application Number:
JP2015207076A
Publication Date:
April 27, 2017
Filing Date:
October 21, 2015
Export Citation:
Assignee:
NIPPON STEEL & SUMITOMO METAL CORP
International Classes:
C22C38/00; C21D8/02; C22C38/58
Domestic Patent References:
| JPH02217417A | 1990-08-30 | |||
| JP2007162101A | 2007-06-28 | |||
| JP2015040322A | 2015-03-02 | |||
| JP2012241274A | 2012-12-10 | |||
| JP2012241273A | 2012-12-10 | |||
| JP2008240004A | 2008-10-09 |
Foreign References:
| US20100263773A1 | 2010-10-21 |
Attorney, Agent or Firm:
Patents corporation Blitas