| 摘要 |
Provided is a high strength hot-dip galvanized steel sheet having a tensile strength of at least 1180 MPa and excellent impact resistance and bending workability, wherein: the steel sheet satisfies a specific alloy composition; the steel sheet is obtained from 0-10% area ratio of ferrite, 15-60% area ratio of martensite, 20-50% area ratio of tempered martensite, and 20-50% area ratio of bainitic ferrite; the respective mean grain sizes of the massive martensite, tempered martensite, and bainitic ferrite are 15 µm or less; the value obtained by subtracting the tempered martensite area ratio from the bainitic ferrite area ratio is 20% or less; in the total martensite area ratio, the area ratio of martensite for which the neighboring phase is obtained solely from martensite is 5% or less; and the value obtained by subtracting the Vickers hardness at a depth of 20 µm from the steel sheet surface from the Vickers hardness at a depth of 100 µm from the steel sheet surface is 30 or more. Also provided is a manufacturing method therefor. |
