Operational factors affecting the hot dip galvanizing steel

An evaluation by hot dip galvanizing on steel after a 1; 2 and 3-minutes immersion was studied. These samples were carried out for evaluating microhardness and thickness measurements. Electrochemical techniques were used to determined the corrosion rate of steel in acid pickling 5; 10 and 16% HCl; rinsed with water of pH 2.50; 3.50 and 4.50 and hot dip galvanized steel in 3.5% NaCl. Certain operational parameters were analyzed, such as the aging bath (HCl), and elimination of the rinsing stage, to observe their influence in the hot dip galvanizing coating. It was found that an increase of coating thickness of hot dip galvanizing steel decreased the corrosion rate and the microhardness. Surfaces of alloy layer of the coating were examined by scanning electron microscope (SEM). SEM measurements was determined that when obvious the rinsing, the chlorine can be catched between two layers (interface), and soon migrates of the outermost alloy layer of the coating (Delta) towards the innermost one (Gamma).