Title:
HOT-PRESSED MEMBER AND METHOD FOR MANUFACTURING SAME, AND COLD-ROLLED STEEL SHEET FOR HOT PRESSING AND METHOD FOR MANUFACTURING SAME
Document Type and Number:
WIPO Patent Application WO/2019/003538
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 8 µm or less and the average aspect ratio of prior austenite crystal grains is 2.5 or less, the volume fraction of martensite is 90% or greater, there are an average of 20 or more Nb-based deposits having a grain size of less than 0.10 µm per 100 µm2 of a cross section parallel to the thickness direction of the member, and the standard deviation of the Vickers hardness measured at 200 µm intervals on the member surface is 40 or less, whereby the hot-pressed member not only has extremely high tensile strength after hot pressing, but can also be provided with excellent delayed fracture resistance and high tensile shear stress after resistance spot welding.
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/JP2018/013714
Publication Date:
January 03, 2019
Filing Date:
March 30, 2018
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; C21D1/18; C21D9/00; C21D9/46; C22C38/12; C22C38/60
Domestic Patent References:
| WO2011158818A1 | 2011-12-22 | |||
| WO2013105631A1 | 2013-07-18 |
Foreign References:
| JP2014015638A | 2014-01-30 | |||
| JP2013122076A | 2013-06-20 | |||
| JP2008308732A | 2008-12-25 | |||
| US20090238715A1 | 2009-09-24 | |||
| JP2015113500A | 2015-06-22 | |||
| JP2014122398A | 2014-07-03 | |||
| JP2008308732A | 2008-12-25 |
Other References:
See also references of EP 3647449A4
Attorney, Agent or Firm:
SUGIMURA Kenji (JP)
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