| 摘要 |
A high-strength steel sheet having a tensile strength of at least 590 MPa and excellent bending properties has a chemical composition containing C: 0.03 - 0.20 %, Si: 0.005 - 2.0 %, Mn: 1.2 - 3.5 %, P ‰¤ 0.1 %, S: ‰¤ 0.01 %, sol. Al: 0.001 - 1.0 %, N: ‰¤ 0.01 %, and Bi: 0.0001 - 0.05 %, optionally Ti: ‰¤ 0.3 %, Nb: ‰¤ 0.3 %, V: ‰¤ 0.3 %, Cr: ‰¤ 1 %, Mo: ‰¤ 1 %, Cu: ‰¤ 1 %, Ni: ‰¤ 1 %, Ca: ‰¤ 0.01 %, Mg: ‰¤ 0.01 %, REM: ‰¤ 0.01 %, Zr: ‰¤ 0.01 %, and B: ‰¤ 0.01 %, wherein the Mn segregation ratio (Mn max /Mn av ) calculated from the average Mn concentration (Mn av ) and the maximum Mn concentration (Mn max ) at a depth of 1/20 of the sheet thickness from the surface of the steel sheet is less than 1.30. |
