RECTANGULAR STEEL TUBE AND METHOD FOR MANUFACTURING SAME, AND BUILDING STRUCTURE

Title:

RECTANGULAR STEEL TUBE AND METHOD FOR MANUFACTURING SAME, AND BUILDING STRUCTURE

Document Type and Number:

WIPO Patent Application WO/2020/170774

Kind Code:

A1

Abstract:

Provided are a rectangular steel tube and a method for manufacturing same, and a building structure employing said rectangular steel tube. The present invention provides a rectangular steel tube which has flat plate portions and corner portions, and which has a specific component composition, wherein: the steel structure in a position at a depth 1/4 of a plate thickness t from an outer surface of the steel tube is such that ferrite occupies at least 55% and at most 80% by area ratio, and the mean aspect ratio of the hard phase is 0.1 to 0.8; the flat plate portions have a yield strength (YS) at least equal to 350 MPa and a tensile strength (TS) at least equal to 520 MPa; the ratio of YS in the flat plate portions relative to the corner portions is at least equal to 0.80 and at most equal to 0.90; the ratio of TS in the flat plate portions relative to the corner portions is at least equal to 0.90 and at most equal to 1.00; the Charpy absorbed energy of the flat plate portions at -40°C is at least equal to 100 J; and the radius of curvature R of the corner portions is at least equal to (2.3×t) and at most equal to (2.9×t).

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Inventors:

IDE SHINSUKE (JP)
MATSUMOTO AKIHIDE (JP)
MATSUMOTO ATSUSHI (JP)
OKABE TAKATOSHI (JP)

Application Number:

PCT/JP2020/003841

Publication Date:

August 27, 2020

Filing Date:

February 03, 2020

Export Citation:

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Assignee:

JFE STEEL CORP (JP)

International Classes:

B21C37/08; B21D5/06; C21D8/02; C21D8/10; C22C38/00; C22C38/06; C22C38/58; E04B1/24; E04C3/32

Domestic Patent References:

WO2018110152A1

2018-06-21

Foreign References:

JP2018095904A	2018-06-21
JP2018053281A	2018-04-05
JP2016011439A	2016-01-21
JP2007119899A	2007-05-17
JPH0569039A	1993-03-23
KR20140118313A	2014-10-08

Attorney, Agent or Firm:

KUMASAKA Akira et al. (JP)

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