Effect of Magnetic Field on Anodic Process of Axle Steel in Sodium Bicarbonate Solution with Chlorides

The effect of 0.4 T magnetic field on the anodic process of axle steel in sodium bicarbonate solution with or without chloride ions was studied by electrochemical test combined with surface morphology observation. Results of potentiodynamic polarization curves showed that 0.4 T magnetic field increased the anodic current density in the prepassive range, didn't affect the transpassive range in sodium bicarbonate solution, but increased the current density in the transpassive range in sodium bicarbonate solution with chlorides. Pitting on the surface of the sample after the polarization curve test in the solution to which the magnetic field was applied was more serious than that without the magnetic field. Results of potentiostatic polarization test showed that: in the pre-passivation zone of the polarization curve, the magnetic field slowed the current decay rate. In the passivation zone, the magnetic field increased the initial current density and increased the number of pitting. In the transpassive zone, the magnetic field significantly increased the current density and caused more and larger pitting.