Title:
PROCESS FOR PRODUCING PRESS-FORMED PRODUCT, AND PRESS-FORMED PRODUCT
Document Type and Number:
WIPO Patent Application WO/2013/133164
Kind Code:
A1
Abstract:
This process includes: heating a starting steel blank for hot pressing to a temperature ranging from the Ac3 transformation temperature to 950°C and then initiating the press forming of the steel blank; and cooling the press-formed steel blank to a temperature lower than the martensitic transformation initiation temperature (Ms) while keeping the press-formed steel blank at the bottom dead center and ensuring an average cooling rate of 20°C/sec or more in the mold. The starting steel blank has a prescribed chemical composition and fulfills the requirements: Ti-containing precipitates which are contained in the steel blank and which have equivalent circle diameters of 30nm or less have a mean equivalent circle diameter of 3nm or more; and the quantity of precipitated Ti in the steel blank and the total quantity of Ti therein satisfy relationship (1). Quantity of precipitated Ti (mass%) - 3.4[N] ≥ 0.5 × [total quantity of Ti (mass%) - 3.4[N]] ··· (1) (wherein [N] represents the content (mass%) of N in the steel)
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Inventors:
MURAKAMI TOSHIO
HATA HIDEO
NAITOU JUNYA
OKITA KEISUKE
IKEDA SHUSHI
HATA HIDEO
NAITOU JUNYA
OKITA KEISUKE
IKEDA SHUSHI
Application Number:
PCT/JP2013/055675
Publication Date:
September 12, 2013
Filing Date:
March 01, 2013
Export Citation:
Assignee:
KOBE STEEL LTD (JP)
International Classes:
C21D9/00; B21D22/20; C22C38/00; C22C38/60
Foreign References:
| JP2010043323A | 2010-02-25 | |||
| JP2007211276A | 2007-08-23 | |||
| JP2005097725A | 2005-04-14 | |||
| JP2008019453A | 2008-01-31 | |||
| JP2010065292A | 2010-03-25 | |||
| JP2010065293A | 2010-03-25 | |||
| JP2010065294A | 2010-03-25 | |||
| JP2010065295A | 2010-03-25 |
Other References:
ISJJ INT., vol. 33, no. 7, 1933, pages 776
Attorney, Agent or Firm:
HAMADA Yuriko et al. (JP)
Yuriko Hamada (JP)
Yuriko Hamada (JP)
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Claims: