Title:
HOT-PRESS MEMBER AND METHOD FOR PRODUCING SAME, AND COLD-ROLLED STEEL SHEET FOR HOT PRESSING
Document Type and Number:
WIPO Patent Application WO/2019/003445
Kind Code:
A1
Abstract:
Provided is a hot-press member that can have not only very high tensile strength after hot pressing but also excellent delayed fracture resistance and high tensile shear stress after resistance spot welding, the hot-press member being obtained by appropriately adjusting the component composition thereof and making the microstructure thereof such that the average crystal grain size of prior austenite is 8 μm or less, the average aspect ratio of prior austenite crystal grains is 2.5 or less, the volume fraction of martensite is 90% or more, the average number of Nb-based precipitate having a grain size of less than 0.10 μm in a 100-μm2-section of a steel sheet is 20 or more, and the standard deviation of Vickers hardness measured every 200 μm on the surface of the steel sheet is 40 or less.
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/JP2017/024255
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; C22C38/12; C22C38/60
Domestic Patent References:
| WO2011158818A1 | 2011-12-22 | |||
| WO2013105632A1 | 2013-07-18 |
Foreign References:
| JP2014015638A | 2014-01-30 | |||
| JP2013122076A | 2013-06-20 |
Attorney, Agent or Firm:
SUGIMURA Kenji (JP)
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