US 12,241,134 B2
High-strength hot-rolled plated steel sheet, and method for producing same
Kyong Su Park, Pohang-si (KR); and Jaeyong Chae, Pohang-si (KR)
Assigned to POSCO CO., LTD, Pohang-si (KR)
Appl. No. 16/772,987
Filed by POSCO, Pohang-si (KR)
PCT Filed Mar. 6, 2018, PCT No. PCT/KR2018/002667
§ 371(c)(1), (2) Date Jun. 15, 2020,
PCT Pub. No. WO2019/124638, PCT Pub. Date Jun. 27, 2019.
Claims priority of application No. 10-2017-0178850 (KR), filed on Dec. 22, 2017.
Prior Publication US 2020/0392595 A1, Dec. 17, 2020
Int. Cl. C21D 8/02 (2006.01); C21D 9/46 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/12 (2006.01); C22C 38/14 (2006.01); C22C 38/16 (2006.01)
CPC C21D 8/0226 (2013.01) [C21D 8/02 (2013.01); C21D 8/0205 (2013.01); C21D 9/46 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C22C 38/16 (2013.01); C21D 8/0263 (2013.01); C21D 2211/001 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01); C21D 2211/009 (2013.01)] 3 Claims
 
1. A high-strength hot-rolled plated steel sheet, comprising consisting of:
in a unit of wt %, C at 0.05-0.5 wt %, Mn at 0.1-3.0 wt %, Si at 0.08 wt % or less excluding 0 wt %, P at 0.05 wt % or less excluding 0 wt %, S at 0.03 wt % or less excluding 0 wt %, Nb at 0.01 wt % or less excluding 0 wt %, B at 0.0005-0.005 wt %, Ti at 0.005-0.2 wt %, Cr at 0.5 wt % or less excluding 0 wt %, and a remainder of Fe and inevitable impurities,
wherein a microstructure thereof includes, as a volume fraction, 90 vol % or more of tempered martensite and 5 vol % or less of at least one of bainite, ferrite, pearlite, and residual austenite;
a tensile strength thereof is 719 MPa to 901 MPa, and a yield strength thereof is 659 MPa to 833 MPa; and
a ratio of yield strength to tensile strength is 0.85 or more,
wherein a thickness of the steel sheet is 1.8 mm or less, and
wherein the yield strength and the thickness of the steel sheet satisfy [Formula 1]:
Thickness of steel sheet in a unit of mm−Yield strength in a unit of MPa/1000≤1.25.  [Formula 1]