LCCA-2
EFFECT OF CHLORIDE CONCENTRATION ON THE
CORROSION RATE IN CARBON STEEL
Hisham A Elfergani and Ayad A Abdalla
Faculty of Engineering, University of Benghazi, Benghazi, Libya,
Email:[email protected]
ABSTRACT
Carbon steel is among the most common materials used in engineering and industrial
applications and represents about 85% of the annual steel production worldwide. The
low corrosion resistance of carbon steel in certain environments, such as in marine
environments, is one of the major problems related to its use. The rate of corrosion of
steel in salt solution depends on the salt concentration and on the amount of dissolved
oxygen in the solution. In this paper, an experimental investigation was performed to
study the effect of sodium chloride concentration (NaCl wt%) on the corrosion rate of
carbon steel. Two cases were considered (i) aerated and (ii) non-aerated solutions to
study the effect of dissolved Oxygen. Furthermore, an experiment was carried out to
evaluate the effectiveness of the application of cathodic protection in the maximum
corrosion rate conditions. Carbon steel samples of known metallurgical composition
were used to perform the experiments. Samples were divided into groups of three
samples each and immersed in solutions of different Chloride concentration ranged
from 1% to 6% (NaCl wt%) in the aerated and non-aerated conditions. Measurements
were taken before and after the experiments and corrosion rate was calculated using
mpy units. Results showed that maximum corrosion rate of steel in non-aerated
solution is 2.374 mpy at 3%wt NaCl chloride concentration while for the aerated
solution maximum corrosion rate is 12.892 mpy at (3 % wt NaCl) showing that the
existence of dissolved oxygen in the solution increases the rate of corrosion.
Additional experiment was conducted to apply cathodic protection on steel samples
using sacrificial anode (SACP) at the worst condition (the maximum corrosion rate) to
inhibit corrosion which indicted that cathodic protection is very effective to prevent
steel corrosion at any chloride concentration.
Keywords: Corrosion, carbon steel, chloride concentration, cathodic protection
O-An-42
Shelmani and Alaib
74