| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot-dip galvanized sheet steel superior in strength/ductility balance, bendability, spot weldability and the adhesiveness of the galvanizing layer, and to provide a manufacturing method therefor. SOLUTION: The hot-dip galvanized steel sheet with high tensile strength has a steel composition comprising, by mass%, 0.06-0.20% C, 0.10% or less Si, 2.0-4.0% Mn, 0.05% or less P, 0.05% or less S, 0.1% or less sol. Al, 0.015% or less N, further one or two elements selected from the group consisting of 0.500% or less Ti and 0.500% or less Nb in a total amount of 0.050% or more, while satisfying the following expression (1): 0.07+(Ti+Nb)/2+(Cu+Ni)/30-(Mn/100+P+Si/2+Mo/50+Cr/100)>0, and the balance Fe with impurities; has ferrite with an average grain size of 5μm or smaller; and has a hard secondary phase with an average diameter of 5μm or smaller. The hot-dip galvanized steel sheet may contain 0.25% or less Si, and further one or two elements selected from the group consisting of 1.5% or less Cu and 1.5% or less Ni in a total amount of 0.03% or more. COPYRIGHT: (C)2007,JPO&INPIT
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