Title:
HOT-PRESSED MEMBER AND METHOD FOR MANUFACTURING SAME, AND COLD-ROLLED STEEL SHEET FOR HOT PRESSING
Document Type and Number:
WIPO Patent Application WO/2019/003449
Kind Code:
A1
Abstract:
In the hot-pressed member according to the present invention, after the component composition thereof is properly adjusted, the microstructure thereof is configured so that the average grain size of prior austenite crystal grains is 7.5 µm or less, the volume fraction of martensite is 95% or greater, there are an average of 10 or more Nb- and Ti-based deposits having a grain size of less than 0.10 µm per 100 µm2 of steel sheet cross-sectional area in a range from the steel sheet surface to a depth of 100 µm in the sheet thickness direction, and the B concentration of prior austenite grain boundaries is also at least 3.0 times the B concentration in a position separated 5 nm from the grain boundaries, whereby the hot-pressed member can be provided with an extremely high tensile strength of 1780 MPa or greater after hot pressing as well as excellent resistance to cracking in resistance welding.
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Inventors:
TAKASHIMA KATSUTOSHI (JP)
KOBAYASHI TAKASHI (JP)
FUNAKAWA YOSHIMASA (JP)
NAKAJIMA SEIJI (JP)
KOBAYASHI TAKASHI (JP)
FUNAKAWA YOSHIMASA (JP)
NAKAJIMA SEIJI (JP)
Application Number:
PCT/JP2017/024259
Publication Date:
January 03, 2019
Filing Date:
June 30, 2017
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; B21D22/20; C21D1/18; C21D9/00; C21D9/46; C22C38/14; C22C38/60
Domestic Patent References:
| WO2007129676A1 | 2007-11-15 | |||
| WO2015147216A1 | 2015-10-01 |
Foreign References:
| JP2011173135A | 2011-09-08 |
Attorney, Agent or Firm:
SUGIMURA Kenji (JP)
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