KINETIC STUDY OF 1020 CARBON STEEL CORROSION IN HYDROCHLORIC AND NITRIC ACID MEDIA

This study investigates the corrosion mechanism of 1020 carbon steel in strong acid solutions, relevant for industrial applications, using simple and effective laboratory methods. Direct (weight loss) and indirect (pH, ionic conductivity, open circuit potential and polarization curves) negotiations were performed to evaluate the corrosion rate in different concentrations of hydrochloric acid (HCl) and nitric acid (HNO3). In the HCl system, zero-order kinetics were confirmed (k = 10–5 min g–1), indicating a bottleneck in the corrosion mechanism, confirmed by electrochemical tests and metallographic analyses that showed uniform corrosion. In the HNO3 system, corrosion had first-order kinetics in the first 60 min (k = 10–2-10–3 min g–1), followed by passivation of the steel surface due to the presence of nitrate ions. These findings are particularly relevant for the acid pickling industry, where HCl is more stable, while HNO3 accelerates corrosion, requiring additional regulations. The results obtained are useful for the development of corrosion control and prevention strategies, contributing to increase the durability of materials and optimize the efficiency of industrial processes.