PRODUCTION OF HOT DIP GALVANIZED STEEL STRIP

PROBLEM TO BE SOLVED: To obtain a hot dip galvanized steel strip which suppresses the growth of spangles and has good workability. SOLUTION: At the time of spraying the mists of a treating liquid having coolability to the hot dip galvanizing layers just before solidification after adjusting the coating weight of the excess molten zinc sticking to a steel strip pulling up from a hot dip galvanizing bath, the mists uniformed in grain size of 8 to 20 μμ are sprayed to the hot dip galvanizing layers at a collision rate of 67 to 270 m/sec in collision rate and the grain size of the spangles formed on the surfaces of the hot dip galvanizing layers is adjusted to 60 to 1,000 μm. Since the spangles of the correct grain size are formed, the spangle pattern are not reflected on the surfaces of the coating films and the coating excellent in brightness is applied on the steel strip. The occurrence of defects, such as cracks, in the hot dip galvenizing layers by bending, etc., is averted.