Title:
HIGH STRENGTH COLD-ROLLED STEEL SHEET WITH EXCELLENT MOLDABILITY AND MANUFACTURING METHOD THEREFOR
Document Type and Number:
WIPO Patent Application WO/2017/212885
Kind Code:
A1
Abstract:
A high strength cold-rolled steel sheet, wherein: the component composition comprises, in mass%, C: 0.05-0.25%, Si: greater than 0% to at most 3.0%, Mn: 5.0-9.0%, P: greater than 0% to at most 0.100%, S: greater than 0% to at most 0.010%, Al: 0.001-3.0%, Si+Al: 0.8-3.0%, and N: greater than 0% to at most 0.0100%, the balance being iron and unavoidable impurities; the metal structure is made, in area ratio, of at least 40% to less than 80% of ferrite, less than 25% of martensite, and at least 20% of retained austenite, the balance being less than 10%; the small angle grain boundary density in the ferrite is 1.0-2.4 µm/µm2; the average crystal grain size of the retained austenite is 1.5 µm or less; and the average Mn concentration in the retained austenite is greater than 9.0 mass%.
Inventors:
KAKIUCHI ELIJAH
MURAKAMI TOSHIO
KOCHI TAKUYA
SAITO KENJI
MURATA TADAO
MURAKAMI TOSHIO
KOCHI TAKUYA
SAITO KENJI
MURATA TADAO
Application Number:
PCT/JP2017/018576
Publication Date:
December 14, 2017
Filing Date:
May 17, 2017
Export Citation:
Assignee:
KOBE STEEL LTD (JP)
International Classes:
C22C38/00; C21D9/46; C22C38/06; C22C38/58
Domestic Patent References:
| WO2015011510A1 | 2015-01-29 |
Foreign References:
| JP2012237054A | 2012-12-06 | |||
| JP2013076162A | 2013-04-25 |
Attorney, Agent or Firm:
SAMEJIMA, Mutsumi et al. (JP)
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