Title:
PRODUCTION METHOD FOR THICK STEEL PLATE
Document Type and Number:
WIPO Patent Application WO/2011/099408
Kind Code:
A1
Abstract:
Disclosed is a thick steel plate production method wherein: a steel piece having a specified component composition is heated to 1000-1200˚C; then, with the plate-thickness centre temperature at 950-1200˚C, initial rolling is carried out for 4-16 passes at a cumulative rolling reduction rate of 50-95%; next, with the plate-thickness centre temperature at 850-950˚C, latter rolling is carried out for 2-8 passes with each pass being at a rolling reduction rate of 10-25% and pass time being 3-25 seconds; then, initial cooling is carried out wherein the plate-thickness centre temperature is cooled from 750˚C or above to 630-700˚C at a cooling speed of 0.5-8˚C/s; and then latter cooling is carried out wherein the temperature is cooled to 550˚C or cooler, at a cooling speed of 10-50˚C/s. The thick steel plate produced is characterised by having a plate thickness of 10-40mm and yield stress of 315-550 MPa, having a microstructure which is a mixed structure of one or more from among a soft phase ferrite, a hard phase perlite, a bainite, and a martensite, and having a steel plate centre-part ferrite area ratio of 70-95%, an average hard phase Vicker's hardness of 250-500, and an average crystal particle diameter of 5-20 μm.
Inventors:
NAKASHIMA KIYOTAKA (JP)
HOSHINO MANABU (JP)
HOSHINO MANABU (JP)
Application Number:
PCT/JP2011/052188
Publication Date:
August 18, 2011
Filing Date:
January 27, 2011
Export Citation:
Assignee:
NIPPON STEEL CORP (JP)
NAKASHIMA KIYOTAKA (JP)
HOSHINO MANABU (JP)
NAKASHIMA KIYOTAKA (JP)
HOSHINO MANABU (JP)
International Classes:
C21D8/02; B21B1/38; B21B3/00; C22C38/00; C22C38/58
Foreign References:
| JP2004269924A | 2004-09-30 | |||
| JPH04358021A | 1992-12-11 | |||
| JP2003129134A | 2003-05-08 | |||
| JP2004143500A | 2004-05-20 | |||
| JP2004290979A | 2004-10-21 |
Attorney, Agent or Firm:
AOKI, Atsushi et al. (JP)
Aoki 篤 (JP)
Aoki 篤 (JP)
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Claims: