Study of galvanized steel sheet atmospheric corrosion in Addis Ababa region using atmospheric corrosion models

Abstract

The corrosion of metals is a major global issue, and its mitigation issues are always in demand. The main objective of present study is to investigate the long term atmospheric corrosion phenomena for galvanized steel sheet in the region of Addis Ababa in Ethiopia using well established atmospheric corrosion models. In addition the investigation also deals with the cost of coating spend on galvanized steel sheet and their various implications. The use of galvanized steel sheet is immense in Ethiopia and most of the galvanized steel sheet products used for the purpose of fence and roofing, and they are directly affected by the atmospheric corrosion phenomena. The atmospheric corrosion is directly related to the local atmospheric condition, and due to the lack of literature on the issue of atmospheric corrosion study for the developing capital of Ethiopia i.e. Addis Ababa, the present study is designed to study the atmospheric corrosion of the galvanized steel sheet and various cost associated with that. To study the atmospheric corrosion of galvanized steel sheet, standard atmospheric corrosion models were employed namely Feliu et al. model, Kucera et al. model and Yulia et al. model. These studies corroborate the findings of atmospheric corrosion of galvanized steel sheet and validated with the similar region atmospheric corrosion studies performed earlier on the same material. All the models confirmed the trend of the atmospheric corrosion of galvanized steel sheet in the region of urban/industrial atmosphere type. And based on the comparative analysis of all models predictions with experimental results in literature, it is confirmed that the model results are reliable for short and long period of atmospheric corrosion. And it is always noticed that the corrosion loss or corrosion rate found to be less for all the cases, and that happens due to the lower atmospheric pollutant for the considered area of study. Further based on overall analysis, a proposal for decreasing the existing minimum grade zinc coating amount as per Ethiopian standard CES 40 - Grade180 to Grade 100 is provided, which will also satisfy the demand of the commercial usable galvanized steel sheet.