| 摘要 |
<p>An object of the present invention is to provide a high tensile strength galvanized steel sheet having sufficiently high strength and excellent formability (elongation and stretch-flange ability), as well as a method for manufacturing the galvanized steel sheet. Specifically, the present invention provides a high tensile strength galvanized steel sheet having tensile strength of at least 980 MPa and excellent formability, comprising: a hot rolled steel sheet having (i) a composition including by mass %, C: 0.07% to 0.13% (inclusive of 0.07% and 0.13%), Si: 0.3% or less, Mn: 0.5% to 2.0% (inclusive of 0.5% and 2.0%), P: 0.025% or less, S: 0.005% or less, N: 0.0060% or less, Al: 0.06% or less, Ti: 0.10% to 0.14% (inclusive of 0.10% and 0.14%), V: 0.15% to 0.30% (inclusive of 0.15% and 0.30%), Solute V: 0.04% to 0.1% (inclusive of 0.04% and 0.1%), Solute Ti: 0.05% or less, and remainder as Fe and incidental impurities, (ii) microstructure with fine carbides dispersion precipitated therein, the fine carbides containing Ti and V and having the average particle diameter of less than 10 nm, as well as volume ratio with respect to the entire microstructure of at least 0.007, and (iii) matrix as ferrite phase having area ratio with respect to the entire microstructure of at least 97%; and hot-dip galvanized coating or galvannealed coating formed on a surface of the hot rolled steel sheet, wherein contents of C, Ti, V, S and N satisfy formula (1) Ti ‰¥0.10 + (N/14 * 48 + S/32 * 48) and formula (2) 0.8 ‰¤ (Ti/48 + V/51)/(C/12) ‰¤1.2.</p> |
