Title:
STEEL MATERIAL
Document Type and Number:
WIPO Patent Application WO/2023/167318
Kind Code:
A1
Abstract:
Provided is a steel material that can reduce the hydrogen embrittlement susceptibility of bolts. This steel material contains, in mass%, 0.30-0.50% of C, 0.01-0.30% of Si, 0.10-1.50% of Mn, 0.030% or less of P, 0.030% or less of S, 0.01-0.80% of Cr, at least 0.70% and less than 1.50% of Mo, 0.01-0.50% of V, 0.005-0.100% of Al, and 0.0010-0.0300% of N, with the remainder comprising Fe and inevitable impurities, wherein the area percentage of hard phases is at least 90%, the Vickers hardness is 220-400 HV, the number density of cementite in the hard phases is at least 4.0/μm2, the number percentage of cementite having an area of 0.0005-0.0100 μm2 among a plurality of cementite phases in the hard phases is at least 50.0%, and the sample standard deviation of the areas of the plurality of cementite phases in the hard phases is 0.070 μm2 or less.
Inventors:
UMEHARA MIYURI (JP)
KOBAYASHI YUKIKO (JP)
TANIGUCHI SHUNSUKE (JP)
MATSUI NAOKI (JP)
YAMASAKI SHINGO (JP)
SAKIYAMA YUJI (JP)
KOBAYASHI YUKIKO (JP)
TANIGUCHI SHUNSUKE (JP)
MATSUI NAOKI (JP)
YAMASAKI SHINGO (JP)
SAKIYAMA YUJI (JP)
Application Number:
PCT/JP2023/008073
Publication Date:
September 07, 2023
Filing Date:
March 03, 2023
Export Citation:
Assignee:
NIPPON STEEL CORP (JP)
International Classes:
C21D8/06; C21D9/00; C22C38/00; C22C38/24; C22C38/60; C21D1/32
Foreign References:
| JP2004084010A | 2004-03-18 | |||
| JP2004076086A | 2004-03-11 | |||
| JPH05148580A | 1993-06-15 |
Attorney, Agent or Firm:
ASCEND IP LAW FIRM (JP)
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