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Title:
STEEL PLATE, MEMBER, AND METHODS FOR MANUFACTURING SAID STEEL PLATE AND SAID MEMBER
Document Type and Number:
WIPO Patent Application WO/2021/153393
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide a steel plate having a tensile strength of 1310 MPa or greater as well as excellent edge cracking resistance and bendability, a member, and methods for manufacturing said steel plate and said member.　This steel plate has a specific composition and a steel structure in which the area percentage of martensite is 70% or more, the area percentage of bainite is 30% or less, and the total area percentage of ferrite and retained austenite is 5% or less. The number density of carbides having a major axis of 0.5 μm or more at a position corresponding to 1/4 of the steel plate thickness is 60,000/mm2 or less, the number density of inclusion particles having an equivalent circle diameter of 4.0 μm or larger, in a range from 1/4 to 3/4 of the steel plate thickness, is 10/mm2 to 30/mm2, the number density of inclusion particles having an equivalent circle diameter of 4.0 μm or more, in a range from the surface to 1/4 of the thickness of the steel plate, is 27/mm2 or shorter, and the tensile strength of the steel plate is 1310 MPa or greater.

Inventors:
YOSHIOKA SHIMPEI (JP)
KANEKO SHINJIRO (JP)
HONDA YUMA (JP)
Application Number:
PCT/JP2021/001936
Publication Date:
August 05, 2021
Filing Date:
January 21, 2021
Export Citation:
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Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; C21D9/46; C22C38/14; C22C38/60
Domestic Patent References:
WO2018123356A12018-07-05
WO2018062381A12018-04-05
WO2019181950A12019-09-26
Foreign References:
JP2010215958A2010-09-30
JP6388085B22018-09-12
JP5136182B22013-02-06
JP6056790B22017-01-11
Other References:
NAGATAKI YASUNOBUTSUYAMA SEISHIHOSOYA YOSHIHIRO: "Effect of Tempering Temperature on the Bendability of Martensitic Steels", TETSU TO HAGANE, THE IRON AND STEEL INSTITUTE OF JAPAN, vol. 99, no. 3, 2013, pages 245 - 253
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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