Corrosion Behavior of AZ80 Magnesium Alloy Tube Fabricated by Hydrostatic Extrusion

The corrosion behavior of hydrostatically extruded tube AZ80 magnesium alloy in 0.1 mol/L Na2SO4 solution with pH value of 6.1 was investigated by immersion corrosion, weight loss corrosion, and electchemical methods. The results indicated that the corrosion resistance of AZ80 magnesium alloy decreesed because of small grain size and uneven deformation, with more serious corrosion morphology, bigger average corrosion rate, larger corrosion current density in the polarization curves and lower corrosion resistance in the electrochemical impedance spectroscopy plots. This was mainly because of the hydrostatic extrusion which made AZ80 magnesium alloy have large numbers of dislocation tangles. So the residual stress increased the electrochemical activity of magnesium alloy and thus reduced the corrosion resistance of the magnesium alloy.