Galvanic corrosion behavior of AZ91D alloy / 45 steel couple under magnetic field

Galvanic corrosion behavior of AZ91D alloy / 45 steel couple in 3.5 wt.% NaCl solution under 0, 0.2 and 0.4 T magnetic field were studied by microstructure observation, immersion test and electrochemical measurement. The mixed potential theory was used to estimate the galvanic current density and the mixed potential of the galvanic corrosion between AZ91D alloy and 45 steel. The results indicated that magnetic field could accelerate the corrosion of AZ91D alloy, and impede the corrosion process of 45 steel. The effect of magnetic field on corrosion sensibility and corrosion rate of these two alloys increased as the intensity rising. The galvanic corrosion rate of the couple was accelerated by magnetic field. With the magnetic field intensity rising, the galvanic corrosion sensibility and corrosion rate of the couple increased. The effects of magnetic field on the galvanic corrosion performance of the couple and the corrosion behavior of AZ91D alloy and 45 steel were due to the appearance of field gradient force and magnetohydrodynamic (MHD) force. The mixed potential theory has a certain accuracy to estimate the E_couple and i_couple values in this work.