The corrosion of metallic materials in industrial and natural environments,especially localized corrosions such as pitting corrosion, crevice corrosion and stress corrosion cracking, caused huge damage. Some metallic components servicing in corrosive environments can be affected by magnetic fields produced by the special electrical equipment nearby. To analyze and evaluate the corrosion behavior under magnetic field, it is necessary to understand the effect of magnetic field on uniform and localized corrosion.

In this study, the effects of a 0.4T magnetic field on the electrochemical behavior and corrosion morphologies of iron in chloride solutions with sodium nitrite ions were studied by optical microscope (OM), scanning electron microscope (SEM) and several electrochemical methods such as potentiodynamic polarization curve, potentiostatic polarization and electrochemical impedance spectroscopy,

Potentials in different regions of the anodic polarization curves were chosen to for potentiostatic polarization by applying or removing a 0.4T magnetic field. The current density vs. time curves were measured, as shown in Fig. 1. The impact of magnetic field on the surface morphology of the electrodes after potentiostatic polarization were observed.

The anodic current density increased with increasing polarization potential with or without a 0.4T magnetic field. The current density was very low in the passivation regions during potentiostatic polarization, which was reduced by the applied magnetic field, as shown in Fig. 1 a. The effect of the applied magnetic field on the the current density in near the passivation-transpassive transition potential was complex. The applied magnetic field increased the anodic current density under high potentials such as 0.4 V(SCE), as shown in Fig. 1 b.

The changing of pit number and area for iron in chloride solutions with sodium nitrite with polarization potential exhibited differences with or without 0.4 T magnetic field. The impact of magnetic field on the pitting corrosion is closely related to the polarization potentials, polarization time and the initial state of the electrode surface.