| 摘要 |
PROBLEM TO BE SOLVED: To produce an electrogalvanized steel sheet excellent in uniformity in plating appearance by applying electrogalvanizing to a steel sheet having specified surface ferrite grain size in a galvanizing bath contg. a specified amt. of fluoro complex ions. SOLUTION: Electrogalvanizing is applied to the surface of a steel sheet in which the average ferrite grain size on the surface is regulated to <=38μm in a galvanizing bath contg. 100 to 5000ppm fluoro complex ions to form a galvanizing layer. As the above fluoro complex ions, SiF6 <2-> ions and/or BF4 <-> ions by H2 SiF6 , HBF4 or the like is preferably used. Furthermore, as the galvanizing bath, the one of sulfuric acid is preferably used. In this way, the generation of the part nonuniform in the appearance of the plating surface caused by the microscopic nonuniformity in the surface of the base steel sheet is suppressed, and furthermore, luster free from sparkling can be obtd. Moreover, the surface of the plating layer is subjected to chromating treatment and furthermore to treatment of coating essentially consisting of organic matter or inorganic matter according to necessary, by which the surface treated electrogalvanized steel sheet excellent in uniformity in the plating appearance can be obtd.
|
