Title:
ROLLED WIRE ROD
Document Type and Number:
WIPO Patent Application WO/2018/008703
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide a rolled wire rod with excellent hydrogen embrittlement resistance characteristics after spheroidize annealing followed by quenching/tempering for which, even if spheroidize annealing is not performed prior to cold forging or spheroidize annealing time is shortened, the occurrences of cracks during cold forging is effectively limited. The wire rod has a specified composition. When the respective contents (mass%) of Ti, N and S are [Ti], [N] and [S], respectively, when [S]≤0.0010, [Ti] is (4.5×[S]+3.4×[N]) to (0.008+3.4×[N]) while when [S]≥0.0010, [Ti] is (4.5×[S]+3.4×[N]) to (8.0×[S]+3.4×[N]). The internal structure is a mixed structure of ferrite and pearlite in which the ferrite fraction in area ratio is at least 40%. In a cross-section at a plane that includes the axial direction, when the diameter is D (mm), the average area of sulfides present in the range from the outermost layer to the D/8 position is 6 µm2 or less. The average aspect ratio of the sulfides is 5 or less.
Inventors:
MATSUI NAOKI (JP)
NEISHI YUTAKA (JP)
KOSAKA MAKOTO (JP)
NEISHI YUTAKA (JP)
KOSAKA MAKOTO (JP)
Application Number:
PCT/JP2017/024715
Publication Date:
January 11, 2018
Filing Date:
July 05, 2017
Export Citation:
Assignee:
NIPPON STEEL & SUMITOMO METAL CORP (JP)
International Classes:
C22C38/00; C22C38/32; C22C38/54; C21D8/06
Domestic Patent References:
| WO2016080315A1 | 2016-05-26 | |||
| WO2013183648A1 | 2013-12-12 |
Foreign References:
| JP2000192148A | 2000-07-11 | |||
| JP2007277705A | 2007-10-25 | |||
| JP2014148739A | 2014-08-21 | |||
| JP3443285B2 | 2003-09-02 | |||
| JP5486634B2 | 2014-05-07 | |||
| JPH09104945A | 1997-04-22 |
Other References:
See also references of EP 3483293A4
Attorney, Agent or Firm:
AOKI, Atsushi et al. (JP)
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