| 摘要 |
PURPOSE:To produce an alloyed and galvanized steel sheet by subjecting one or both surfaces of a cold rolled steel sheet to galvanizing by vacuum deposition then heating the same in a batch annealing furnace in a non-oxidizing or weakly reducing atmosphere thereby alloying the galvanizing layer and the steel sheet. CONSTITUTION:The steel sheet 1 is introduced through a gas reduction pretreatment furnace 2, a pressurizing chamber 3 and a sealing roll chamber 4 into a vacuum deposition plating chamber 5 where the plating layer of Zn deposited by evaporation is formed on the bottom surface of the steel sheet 1 in a molten Zn bath 6. The steel sheet is introduced into the 2nd vacuum deposition plating chamber 5' by deflector rolls 7, 7' and Zn is deposited by evaporation on the opposite surface of the sheet as well in the case of forming the plating layers deposited by evaporation on both surfaces of the steel sheet. The steel sheet is then taken out through the sealing roll chamber 4' and the pressurizing chamber 3' and is coiled. The coil is put into the batch annealing furnace where the coil is heated to 250-350 deg.C and is held at said temp. for 1-15hr in the non-oxidizing or weakly reducing atmosphere. The alloy layer of Fe and Zn is formed at the boundary face between the galvanizing layer and the steel sheet, by which the alloyed and galvanized steel sheet is produced.
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