| 摘要 |
The purpose of the present invention is to provide a high-strength steel sheet and a manufacturing method therefor, wherein the steel sheet is ideal for car parts and electrical machine parts, is high-strength with a yield point (YP) of 300 MPa or more, and has reduced in-plane anisotropy of elongation and excellent press-formability. A high-strength steel sheet with small in-plane anisotropy of elongation contains, in mass%, C: 0.040-0.090%, Si: 0.20% or less, Mn: 0.50-0.99%, P: 0.050% or less, S: 0.03% or less, sol. Al: 0.01-0.09%, N: 0.005% or less, Nb: 0.015-0.040%, the remainder being obtained from Fe and unavoidable impurities, and does not contain martensite phases or retained austenite phases. In the texture of the plate surface at the ¼ sheet thickness position of the steel sheet, the mean crystal orientation density (Iα) in the ϕ = 25°-35° range of α-fibers represented by the ODF (crystal orientation distribution function) (ϕ1 = 0°, ϕ2 = 45°, and ϕ = 0°-55°) is 2.0 to 4.0 and the mean crystal orientation density (Iγ) of γ-fibers (ϕ1 = 0°-60°, ϕ2 = 45°, and ϕ = 55°) is 2.0 to 10. |
