| 摘要 |
PROBLEM TO BE SOLVED: To provide a producing method of a hot-rolled galvanized steel sheet, with which after hot-rolling, an intermediate cooling at high speed is executed at a prescribed temp. so as to become >=20% wustite compound in scale and successively, a reduction heat treatment is executed and further, the steel sheet is dipped in zinc bath containing desirable quantity of aluminum to realize excellent coating stickiness and excellent productivity, in the method of producing the hot-rolled galvanized steel sheet at high speed omitting a pickling. SOLUTION: This hot-rolled steel sheet is cooled at the ordinary cooling rate and coiled. Successively, the intermediate cooling at the high speed is executed to the coiled hot-rolled steel sheet to 300-500 deg.C of the cooling temp. thereof so as to become >=20% wustite compound. Further, the reduction heat treatment is executed at 550-700 deg.C for 30-300 sec under atmosphere in >=20% hydrogen. Furthermore, the reduced hot-rolled steel sheet is dipped into the zinc bath having 0.2-5.0 wt.% aluminum content.
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