| 摘要 |
PURPOSE: To dissolve the difference in the initial electroanalysis for zinc caused by microflaws and stains which can not be recognized in the original sheet and to produce a steel sheet excellent in surface appearance, at the time of applying electrogalvanizing to a steel sheet, by previously forming a trace amt. of iron plating substrate and thereafter executing galvanizing. CONSTITUTION: At the time of applying electrogalvanizing to a steel sheet, it is applied with iron plating after pickling to form a substrate adhered with Fe by 5 to 500mg/m<2> . Fe is the main component in the steel sheet to be galvanized and gives no influence to the eluting rate of Zn by which sacrificial corrosion protection is aimed at. Thus, differed from Ni plating substrate treatment or the like, there is no fear of deteriorating the corrosion resistance of the electrogalvanized steel sheet. As for the coating weight of Fe in the iron plating, >=5mg/m<2> is needed from the effect of suppressing inferiority in the appearance, but, since, in the case of >500mg/m<2> , the effect is saturated, the upper limit is regulated to 500mg/m<2> . The coating weight of the galvanizing as the upper layer is not limited in particular, but, from the point of corrosion resistance which is the primary purpose, it is preferably regulated to >=5g/m<2> .
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