The Effect of Tigris River Water Salinity on Corrosion Resistance of Low Carbon Steel (ST37)

Abstract

The aim of this work is to study the effect of Tigris river water salinity on the corrosion resistance of low carbon steel (St37). Water samples were collected from four location in Baghdad city (Towitha, Doraa, Bab - Alshrke and Bab- Almouadem ), some chemical properties were measured and its quality were classified. Specimens were prepared in dimensions of (1.5 X 1.5 X 0.5 cm) according to ASTM G71-31.Corrosion tests were investigated by electrochemical potential state cell where the test specimen represents the positive electrode (anode) while standard calomel electrode (SCE) represents the cathode, the voltage was determined by open circuit and compared with the positional of metal in the electrochemical series it is found equal to (-0.44volt) then voltage was increased ±100 mv, at each 10mv increasing the current was registered, the cathodic and anodic behavior drawn as curves the slopes of them represented by a line of interaction which will represent the corrosion current, then corrosion rate calculated by Tafel equation. The results of corrosion test showed that the river water from Bab – Almouadem area (with salinity 983 µs⁄m at 25 Co( gives the highest corrosion rate because of the high percentage of chloride in comparison with another waters also increasing in the dissolved oxygen which combined with iron to form iron oxide, while the other areas give very close values of corrosion rate.