| 摘要 |
Provided are a high-strength hot-dip galvannealed steel sheet which exhibits excellent ductility, burring workability, and fatigue characteristics, and a process for the production thereof. A high-strength hot-dip galvannealed steel sheet with excellent workability and fatigue characteristics, characterized in that: the steel sheet consists of a steel having a composition which contains, by mass, 0.05 to 0.3% of C, 0.5 to 2.5% of Si, 1.0 to 3.5% of Mn, 0.003 to 0.100% of P, up to 0.02% of S, and 0.010 to 0.1% of Al, with the balance being iron and unavoidable impurities; the structure of the steel sheet comprises, in terms of area fractions, at least 50% of ferrite, 5 to 35% of martensite, and 2 to 15% of pearlite; the mean grain diameter of the martensite is 3µm or less; and the average distance between adjacent martensite grains is 5µm or less. |
