Title:
STEEL SHEET AND METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2018/062380
Kind Code:
A1
Abstract:
Provided is steel sheet and a method for advantageously producing a steel sheet, the steel sheet having a thickness of 0.5-2.6 mm and a high tensile strength (TS) of 1320 MPa or more, and exhibiting excellent delayed fracture resistance characteristics, and especially delayed fracture resistance characteristics of a sheared end face. This steel sheet has a specific constituent composition and has a steel structure whereby the total areal ratio of martensite and bainite is more than 90% and not more than 100% of the overall structure, an inclusion group A that satisfies specific conditions is present at a quantity of 2 groups/mm2 or less, an inclusion group B that satisfies specific conditions is present at a quantity of 5 groups/mm2 or less, carbides which have an aspect ratio of 2.0 or less, have a long axis length of 0.30-2 μm and comprise mainly Fe are present at a quantity of 4000 carbides/mm2 or less, and the average prior γ grain diameter is 6-15 μm.
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Inventors:
ONO YOSHIHIKO (JP)
YOSHIOKA SHIMPEI (JP)
NAKAMURA NOBUYUKI (JP)
HASEGAWA HIROSHI (JP)
YOSHIOKA SHIMPEI (JP)
NAKAMURA NOBUYUKI (JP)
HASEGAWA HIROSHI (JP)
Application Number:
PCT/JP2017/035199
Publication Date:
April 05, 2018
Filing Date:
September 28, 2017
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; C21D9/46; C21D9/52; C22C38/14; C22C38/60
Domestic Patent References:
| WO2016120914A1 | 2016-08-04 | |||
| WO2016111271A1 | 2016-07-14 |
Foreign References:
| JP2016050343A | 2016-04-11 |
Other References:
See also references of EP 3489382A4
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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