The corrosion and mechanical properties of hot dip galvanized steels

Hot dip galvanizing of steel has extensive applications for improving the atmospheric corrosion resistance. During hot dip galvanizing process, many chemical reactions take place, which give rise to the growth of different phases or intermetallic compounds in the coating. The characteristics of the product depend on the presence and distribution of these compounds, and depends on many factors such as the bath and the steel chemical compositions, immersion time, cooling rate, substrate roughness etc. In this work, the performance of galvanized coatings of various compositions against corrosion was tested in Kesternich's, humidity and salt spray chambers. Bare steel, phosphated steel and commercial zinc specimen were tested for comparison. Corrosion rates were calculated from the mass loss data. Hardness, toughness and tensile strength were determined prior to and after the corrosion tests, in order to correlate the corrosion induced structural changes to the material mechanical properties.