Title:
RECTANGULAR STEEL PIPE AND METHOD FOR MANUFACTURING SAME, HOT-ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING SAME, AND BUILDING STRUCTURE
Document Type and Number:
WIPO Patent Application WO/2023/053837
Kind Code:
A1
Abstract:
Provided are a rectangular steel pipe and a method for manufacturing the same, and a hot-rolled steel sheet and a method for manufacturing the same. This rectangular steel pipe and hot-rolled steel sheet have a prescribed component composition, the steel structure in a position at a depth of 1/4t, where t is the wall thickness from the pipe outer surface and the steel sheet surface, comprises in terms of volume fraction, more than 30% ferrite and at least 10% bainite, the total of ferrite and bainite being 75-95%, and the remainder being one or more selected from pearlite, martensite, and austenite, the number of crystal grains having a long axis of 50 µm or greater and a ratio of long axis and short axis (= (long axis)/(short axis)) of 4.0 or greater is 30/mm2 or fewer, where a crystal grain is a region surrounded by a boundary where the orientation difference between adjacent crystals is at least 15°, and the volume fraction of crystal grains having an equivalent circle diameter of 40.0 µm or greater is 20% or less.
Inventors:
IWATA NAOMICHI (JP)
MATSUMOTO AKIHIDE (JP)
IDE SHINSUKE (JP)
MATSUMOTO AKIHIDE (JP)
IDE SHINSUKE (JP)
Application Number:
PCT/JP2022/032953
Publication Date:
April 06, 2023
Filing Date:
September 01, 2022
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C21D8/02; B21C37/15; C21D8/10; C22C38/00; C22C38/14; C22C38/58
Domestic Patent References:
| WO2018235244A1 | 2018-12-27 | |||
| WO2020209060A1 | 2020-10-15 |
Foreign References:
| JP2012132088A | 2012-07-12 | |||
| JP2000144316A | 2000-05-26 | |||
| JP2021147630A | 2021-09-27 | |||
| US20200255920A1 | 2020-08-13 |
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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