| 摘要 |
PURPOSE:To cheaply obtain a perfectly one-side hot dipped steel sheet by introducing a steel sheet into a hot dipping bath while contacting a side not to be hot dipped to C powder as a hot dipping preventive agent by a specified method. CONSTITUTION:Steel strip 1 is passed through degreasing vessel 2, washing vessel 3, sulfuric acid-washing vessel 4, washing vessel 5, hot stove 6, etc., and a side of degreased and washed strip 1 which side is not to be galvanized is coated with an aq. soln. of ZnCl2 and NH2Cl by means of roll coater 7 and dried at about 200 deg.C in drying furnace 8 of a N2 atmosphere. Strip 1 is then introduced into molten zinc bath 10 provided with 150 mm thick floating C powder 9 of an average diameter of 20 mum at non-galvanizing side. The galvanized strip is passed by roll 11 to regulate the amt. of molten zinc adhered, and attached C is removed with roll 12. In the bath a side not to be galvanized is covered with the C powder to prevent galvanizing, and a perfectly one-side galvanized steel sheet is cheaply obtd. without requiring complex pretreatment of a conventional method. |
