Optimizing Hot Dip Galvanizing Operations of Steel Sheets for Better Quality

Abstract

Hot dip galvanizing operations were conducted in the laboratory for steel sheets of 0.20 mm, 0.60 mm and 1.0 mm thicknesses. The operations  were carried out using 99.8% zinc with small amounts of aluminium addition at 450^oC   for  1.0 min immersion duration at withdrawal speeds of 3 m/min, 4 m/min and 5 m/min.   Steel plates were withdrawn into a clean area in an open space where they were rapidly cooled. The quality of the galvanized coatings produced was evaluated by their appearance, lustre and uniformity. The results obtained showed varying quality parameters for different thicknesses.  Gauges 18, 22 and 28 steel sheets had best quality in terms of coating lustre and uniformity at respective withdrawal speeds of 3m/min, 4 m/min and 5 m/min. The differences in the heat capacities of different gauges led to their different responses in cooling time which accounted for the results obtained.