Title:
STEEL PIPE, COMPONENT FOR VEHICLES, METHOD FOR PRODUCING STEEL PIPE AND METHOD FOR PRODUCING COMPONENT FOR VEHICLES
Document Type and Number:
WIPO Patent Application WO/2023/157975
Kind Code:
A1
Abstract:
The present invention provides: a component for vehicles having excellent fatigue strength; a steel pipe which enables the production of a component for vehicles having excellent fatigue strength; a method for producing this steel pipe; and a method for producing this component for vehicles. A steel pipe according to the present disclosure comprises a base material and an oxide coating film on the base material. The base material has a chemical structure that contains, in mass%, 0.23% to 0.50% of C, 0.01% to 0.50% of Si, 0.50% to 2.50% of Mn, 0.050% or less of P, 0.0100% or less of S, 0.0100% or less of N and 0.0100% or less of O, with the balance being made up of Fe and impurities; and the base material has a microstructure that is composed, in area ratios, of 20% to 60% of ferrite and 40% to 80% of pearlite. The oxide coating film is composed, in terms of the X-ray diffraction peak intensity ratios, of 70% or more of Fe3O4, 20% or more of Fe2O3 and 10% or less of FeO, with the balance being made up of impurities, if the sum of the X-ray diffraction peak intensities of Fe3O4, Fe2O3 and FeO is taken as 100%; the oxide coating film has a thickness of 0.80 µm to 2.50 µm; and the standard deviation of the thickness is 0.90 µm or less.
Inventors:
HAYAKAWA MAMORU (JP)
HAMAISHI MITSUHIRO (JP)
SAKAMOTO SHINYA (JP)
HAMAISHI MITSUHIRO (JP)
SAKAMOTO SHINYA (JP)
Application Number:
PCT/JP2023/006173
Publication Date:
August 24, 2023
Filing Date:
February 21, 2023
Export Citation:
Assignee:
NIPPON STEEL CORP (JP)
International Classes:
C21D8/10; C21D9/08; C22C38/00; C22C38/58
Domestic Patent References:
| WO2020129337A1 | 2020-06-25 | |||
| WO2018079398A1 | 2018-05-03 |
Foreign References:
| JP2005105341A | 2005-04-21 | |||
| JP2018506642A | 2018-03-08 | |||
| JP2013007105A | 2013-01-10 | |||
| JP2019183267A | 2019-10-24 | |||
| KR20200076797A | 2020-06-30 |
Attorney, Agent or Firm:
ASCEND IP LAW FIRM (JP)
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