Title:
熱延鋼板、角形鋼管、およびその製造方法
Document Type and Number:
Japanese Patent JP7031477
Kind Code:
B2
Abstract:
To provide a high strength, high toughness, and low yield ration thick hot rolled steel sheet for building structure members, and a rectangular steel tube.SOLUTION: There is provided a hot rolled steel sheet containing prescribed amounts of C, Si, Mn, P, S, Al, and N, containing Nb:0.015 to 0.045 mass%, and the balance Fe with inevitable impurities, in which an alloy structure of the hot rolled steel sheet consists of a main phase and a second phase, the main phase is ferrite and has hardness of 150 to 200 Hv in a micro Vickers hardness test, the second phase is pearlite, or pearlite and bainite, second phase frequency defined in the following (1) formula at 1/4 thickness of the sheet is 0.05 to 0.15, second phase area rate is 3 to 15%, average crystal particle diameter of the main phase and the second phase at 1/4 thickness of the sheet is 10 to 25 μm. (particle number of second phase particles crossing a line with prescribed length)/(total particle number of the main particle and the second phase particle crossing the line with the prescribed length) (1).SELECTED DRAWING: None
Inventors:
Shinsuke Kai
Osamu Yoshida
Osamu Yoshida
Application Number:
JP2018089950A
Publication Date:
March 08, 2022
Filing Date:
May 08, 2018
Export Citation:
Assignee:
Nippon Steel Corporation
International Classes:
C22C38/00; C21D8/02; C21D8/10; C21D9/46; C22C38/12; C22C38/54
Domestic Patent References:
| JP8246095A | ||||
| JP2012153963A | ||||
| JP2016011439A | ||||
| JP2016125077A | ||||
| JP2013245360A | ||||
| JP2009209443A |
Foreign References:
| WO2013153679A1 | ||||
| WO2011052095A1 |
Attorney, Agent or Firm:
Intellectual Property Office