| 摘要 |
PROBLEM TO BE SOLVED: To produce an Al-containing hot-dip galvanized steel sheet excellent in uniformity of spangle, having attractive external surface appearance, and excellent also in design characteristic by applying hot dip galvanizing containing specific amounts of Al to the surface of a steel sheet containing specific amounts of Al and N. SOLUTION: A steel sheet, containing A (Alwt.%) and N (Nwt.%) so that 6<=(135×A+1500×N)<=8 is satisfied, is subjected to hot-dip galvanizing containing 20-95wt.% Al. At this time, the relation between the cooling rate C( deg.C/sec) of the steel sheet after plating and the average spangle diameter (d)(mm) of the plating film satisfies inequality 0.9-0.13×(C-9)<1/2> <=d<= 1.15-0.13×(C-9)<1/2> . In the inequality, (d)(mm) is determined by arbitrarily selecting ten places from a steel sheet sample of 10cm×10cm, counting the number of spangles crossing a length of 1cm, and satisfying (the average spangle diameter) (d)(mm)=100/(the total number of the counts in ten places). Further, the cooling rate C is a cooling rate (±C/sec) until the plating film of the steel sheet is solidified.
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