PURPOSE: To inhibit the growth of spangle pattern at the surface of a steel sheet galvanized with zinc or zinc alloy, by spraying, while regulating spraying speed and spraying quantity, a metal-oxide powder of the prescribed grain size or below on a strip which is pulled up from a plating bath and in which coating weight is regulated, before the plating layer of the strip is solidified.
CONSTITUTION: In a hot dip galvanizing line by ordinary Sendzimir process or nonoxidizing furnace method, the steel sheet hot-dip-galvanized with zinc or zinc alloy which is pulled up from a plating bath and subjected to coating weight regulation is sprayed with the metal-oxide powder of ≤50μm grain size, such as Al2O3, etc., at ≥5m/sec spraying speed by ≥0.01g/m2 per unit area before the plating layer of the plated steel sheet is solidified. In this way, the size of the spangle at the plated surface is regulated to ≤1mm diameter and the occurrence of visible spangle pattern is inhibited, so that galvanized steel sheet having uniform appearance can be obtained.
ASAKAWA KENICHI
OMORI TAKAYUKI
SAWADA KEN
JITSUHARA IKUO
JPS54139839A | 1979-10-30 | |||
JP42022844A |