Title:
HOT-ROLLED STEEL SHEET AND METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2013/103125
Kind Code:
A1
Abstract:
Provided are a high-strength hot-rolled steel sheet having reliable low-temperature toughness as well as exceptional stretch flangeability due to control having been maintained over the structural fractions and difference in hardness between structures, and a method for producing the high-strength hot-rolled steel sheet. A hot-rolled steel sheet characterized in containing 0.01 to 0.2% of C, 0.001 to 2.5% or less of Si, 0.10 to 4.0% or less of Mn, 0.10% or less of P, less than 0.03% of S, 0.001 to 2.0% of Al, less than 0.01% of N, (0.005+48/14[N]+48/32[S]) to 0.3% inclusive of Ti, 0 to 0.06% of Nb, 0 to 1.2% of Cu, 0 to 0.6% of Ni, 0 to 1% of Mo, 0 to 0.2% of V, 0 to 2% of Cr, 0 to 0.01% of Mg, 0 to 0.01% of Ca, 0 to 0.1% of REM, and 0 to 0.002% of B; having an aggregate structure in which mean X-ray random intensity ratio for the sheet-surface {100}<011> to {223}<110> orientation group is 6.5 or less, and the mean X-ray random intensity ratio for the {332}<113> crystal orientation is 5.0 or less in a sheet thickness center located 3/8 to 5/8 the distance from the surface of the steel sheet in the thickness direction; and having a microstructure in which the total surface area of tempered martensite, martensite, and lower bainite exceeds 85%, and the mean crystal grain size is 12.0 μm or less.
Inventors:
SHUTO HIROSHI (JP)
YOKOI TATSUO (JP)
KANZAWA YUUKI (JP)
FUJITA NOBUHIRO (JP)
NIIYA RYOHTA (JP)
SAITOH SHINYA (JP)
YOKOI TATSUO (JP)
KANZAWA YUUKI (JP)
FUJITA NOBUHIRO (JP)
NIIYA RYOHTA (JP)
SAITOH SHINYA (JP)
Application Number:
PCT/JP2012/083918
Publication Date:
July 11, 2013
Filing Date:
December 27, 2012
Export Citation:
Assignee:
NIPPON STEEL & SUMITOMO METAL CORP (JP)
International Classes:
C22C38/06; C21D8/02; C21D9/46; C22C38/58
Domestic Patent References:
| WO2012014926A1 | 2012-02-02 | |||
| WO2012121219A1 | 2012-09-13 |
Foreign References:
| JP2005206920A | 2005-08-04 | |||
| JP2003160836A | 2003-06-06 | |||
| JP2009263718A | 2009-11-12 | |||
| JP2011052321A | 2011-03-17 | |||
| JP2011017044A | 2011-01-27 | |||
| JPH07252592A | 1995-10-03 |
Other References:
K. SUGIMOTO ET AL., ISIJ INTERNATIONAL, vol. 40, 2000, pages 920
KISHIDA, SHINNITTETSU GIHO, 1999, pages 13
KISHIDA, SHINNITTETSU GIHO, 1999, pages 13
Attorney, Agent or Firm:
EINSEL Felix-Reinhard et al. (JP)
アインゼル Felix-Reinhardt (JP)
アインゼル Felix-Reinhardt (JP)
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