静液挤压制备的AZ80镁合金管材的腐蚀行为

Corrosion Behavior of AZ80 Magnesium Alloy Tube Fabricated by Hydrostatic Extrusion

采用浸泡腐蚀试验、失重腐蚀试验以及电化学方法等研究了静液挤压AZ80镁合金在pH 6.1的0.1mol/L Na2SO4溶液中的腐蚀行为。结果表明,静液挤压使得AZ80镁合金晶粒尺寸变小且变形不均匀,降低了镁合金在含硫介质中的耐蚀性,表现为浸泡试验中更严重的表面腐蚀形貌、失重试验中更大的平均腐蚀速率、极化曲线中更大的腐蚀电流密度以及电化学阻抗谱中更低的极化电阻。这主要是因为静液挤压变形使得AZ80镁合金内部存在大量的位错缠结,这样产生的残余内应力会增大镁合金的电化学活性,降低镁合金的耐蚀性。

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.