Cavitation—Corrosion Studies on Welded and Nonwelded Duplex Stainless Steel in Aqueous Lithium Bromide Solutions

Abstract

The objective of this work was to study the effect of dynamic fl ow conditions (mechanical effect) on the cyclic potentiodynamic and potentiodynamic curves of EN 1.4462, its fi ller metal (EN 1.4462F), and the welded metal (EN 1.4462W) obtained by gas tungsten arc welding (GTAW). The implosion of bubbles on the surface modifi es the electrochemical behavior of these different alloys. Values of open-circuit potentials (OCP), corrosion potentials, corrosion current densities, passivation current densities, pitting potentials, repassivation current densities, repassivation potentials, and anodic hysteresis loops were obtained from potentiodynamic curves at 25°C in 400, 700, and 850 g/L lithium bromide (LiBr) solutions under static and dynamic conditions. It has been determined that the welding causes a deterioration of the corrosion resistance of the duplex stainless steel, and the EN 1.4462W is always the anodic element of the pair comprising welded and nonwelded stainless steel. The corrosion behavior and the repassivation behavior of the alloys are modifi ed by cavitation. The surface of the materials was examined to evaluate the corrosion damage to the samples. The electrode surfaces of the alloys show differences when the attack takes place under static or under dynamic conditions.

The Electrochemistry Behaviour of Carbon Steel in 55% LiBr Solution with A-Mo Inhibitor

“…On the reverse scan, the anodic current density decreased as a consequence of the repassivation phenomenon and a hysteresis loop was observed. A narrow hysteresis loop is a general indicator of low susceptibility of an alloy to localized attack in a given environment [14]. In this sense, repassivation was more difficult in 55% LiBr solution because the amplitude of the anodic loop was the highest; on the contrary, it was easier in the 55% LiBr solution with 800 mg•L -1 A-Mo inhibitor because the amplitude of the loop was the lowest.…”