Document Type and Number:
Japanese Patent JPWO2022045350
Kind Code:
A1
Abstract:
This steel sheet has a chemical compositional makeup of, in mass%, 0.040-0.160% of C, 0.01-0.50% of Si, 0.70-2.50% of Mn, not more than 0.030% of P, not more than 0.020% of S, not more than 0.010% of Al, 0.0010-0.0080% of N, 0.0005-0.0040% of O, 0.003-0.050% of Nb, 0.003-0.024% of Ti, 0.0007-0.0050% of Zr, 0.0007-0.0040% of Insol.Zr, not more than 0.0010% of Sol.Zr, 0.0003-0.0040% of B, and Fe and impurities being the remaining portion, with a relation of BF≤0.0030 satisfied. A metal structure at a 1/4t position of a C-cross section contains not more than 80 area% of bainite. The average length of bainitic ferrite constituting bainite in a long axis direction is not more than 10 μm. The average length of primary austenite grains in the thickness direction at a 1/4t position of an L-cross section is not more than 20 μm. The average of aspect ratios of the primary austenite grains is not less than 2.5. The number density of complex inclusion having a predetermined diameter and a predetermined component is 5-300 pieces/mm2.
Application Number:
JP2022505646A
Publication Date:
March 03, 2022
Filing Date:
August 31, 2021
Export Citation:
Domestic Patent References:
| JP2018090872A | 2018-06-14 | |||
| JP2020117779A | 2020-08-06 | |||
| JPH10306316A | 1998-11-17 | |||
| JP2018003062A | 2018-01-11 |
Foreign References:
| WO2009072559A1 | 2009-06-11 |