Title:
ELECTRIC RESISTANCE WELDED STEEL PIPE FOR MECHANICAL STRUCTURAL COMPONENTS, AND METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2022/259332
Kind Code:
A1
Abstract:
The electric resistance welded steel pipe for mechanical structural components comprises a straight pipe section comprising a base material region and an electric resistance welded region. The chemical composition of the base material region contains, as the mass%, C : 0.30-0.38%, Si : 0.05-0.40%, Mn : 0.50-2.00%, Al : 0.010-0.060%, Ti : 0.005-0.050%, and B : 0.0003-0.0050%. The microstructure in the center of the wall thickness of the base material region is tempered martensite. For both the inner surface side and outer surface side of the base material region, the thickness of a carbon-depleted layer, in which the C concentration is not more than 90% of the C concentration in the chemical composition of the base material region, is less than 0.20 mm, and the thickness of a B-depleted layer, in which the B concentration is not more than 90% of the B concentration in the chemical composition of the base material region, is less than 0.10 mm. Both the Vickers hardness at a location at a depth of 0.5 mm from the inner surface of the base material region and the Vickers hardness at a location at a depth of 0.5 mm from the outer surface of the base material region are at least 420 Hv but less than 510 Hv.
Inventors:
TOMIO YUSAKU (JP)
NAGATA YUKINOBU (JP)
SAKAMOTO SHINYA (JP)
HARA TAKUYA (JP)
NAGATA YUKINOBU (JP)
SAKAMOTO SHINYA (JP)
HARA TAKUYA (JP)
Application Number:
PCT/JP2021/021627
Publication Date:
December 15, 2022
Filing Date:
June 07, 2021
Export Citation:
Assignee:
NIPPON STEEL CORP (JP)
International Classes:
C21D7/06; C21D9/08; C22C38/00; C22C38/58
Domestic Patent References:
| WO2019188224A1 | 2019-10-03 | |||
| WO2019131813A1 | 2019-07-04 | |||
| WO2020230795A1 | 2020-11-19 |
Attorney, Agent or Firm:
TAIYO, NAKAJIMA & KATO (JP)
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