| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot dip galvanized high strength steel sheet having excellent plating adhesion and hole expansibility, and to provide its production method. SOLUTION: The hot dip galvanized high strength steel sheet having excellent plating adhesion and hole expansibility has a composition comprising, by mass, 0.12 to 0.35% C, 0.2 to 1.0% Si, 0.8 to 3.5% Mn,≤0.03% P,≤0.03% S, 0.25 to 1.8% Al, 0.05 to 0.35% Mo and≤0.010% N, and the balance Fe with inevitable impurities, and has a metallic structure composed of ferrite, bainite, tempered martensite in 0.5 to 10% by area ratio and retained austenite in≥7% by volume ratio. Regarding its production method, after annealing at 680 to 930°C in a continuous annealing stage, at the time when it is cooled to a martensitic transformation point or below and is subsequently subjected to hot dip galvanizing, after heating at 250 to 600°C, the hot dip galvanizing treatment is performed. COPYRIGHT: (C)2005,JPO&NCIPI
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