Effect of TIG Welding and Rare Earth Elements Alloying on Corrosion Resistance of Magnesium Alloys

The corrosion resistance of the welds made of QE22, ZRE1, and WE43 rare-earth-metals-containing magnesium alloys was investigated in 0.5% NaCl solution saturated with Mg(OH)(2)using the electrochemical methods: linear sweep voltammetry, small amplitude cyclic voltammetry, and electrochemical impedance spectroscopy. These tests elucidated how welding influences the susceptibility to corrosion of that class of magnesium alloys. For the sake of comparison AZ91 magnesium alloy was investigated too. All welds were obtained by tungsten inert-gas welding method. In the case of all investigated alloys welds showed corrosion resistance comparable to the base material. However, all rare-earth-metals-containing magnesium alloys show corrosion resistance inferior to AZ91 alloy. Significant differences in corrosion resistance evaluated by different electrochemical methods were observed.