Effect of Corrosive Media on Corrosion of Hot-Dipped Galvanized Steel 
Lwin Mar Myat Department of Metallurgical Engineering and Materials Science, West Yangon Technological University Hlaing Thar Yar , Yangon, Myanmar [email protected]   
Galvanized steel is one of the most widely used materials for construction of bridge. The bridge of galvanized steel in corrosive media such as marine atmosphere, rainy season atmosphere can cause the serious corrosion problem and this important issue is needed to address. Therefore the objective of this paper is to study how the effect of corrosive media on corrosion of hot-dipped galvanized steel. A corrosion test of hot-dipped galvanized steel was carried out in two different aqueous environments, 3.5% NaCl solution and rain water, using the immersion test. Corrosion behaviour was analysed by salt spray testing. The corrosion characteristics of the corroded samples were investigated by XRD and SEM analysis. The immersion test results show that 3.5% NaCl solution significantly increases the corrosion rate of galvanized steel compared with rain water. According to salt spray test results, white rust corrosion products were found to observe on corroded surfaces. XRD analysis shows that the corrosion products formed on corroded surfaces is Zn5(OH)8Cl2.H2O in both environments. Localized galvanic corrosion mechanism is favourable between zinc coating layers and steel substrate.
Keywords - Hot-dipped galvanized steel, 3.5% NaCl solution, Rain water, Immersion test, Salt spray test.