Corrosion behaviour of friction stir welded rare earth magnesium alloy ZE41 under salt spray test

Magnesium is the lightest structural metal. Magnesium alloys are mixtures of magnesium with other metals (called an alloy), often zinc, manganese, silicon, copper, rare earths and zirconium. The magnesium alloys are having remarkable desirable properties like lightweight, low density (two thirds that of aluminium), good high-temperature mechanical properties. The addition of rare earth elements with the magnesium increases the strength and decreases the weld cracking and porosity during the casting process. Despite, the corrosion property of Magnesium alloy limits its applications. The corrosion behaviour of friction stir welded rare earth magnesium alloy ZE41 was investigated in present study. The friction stir welding was performed on 5mm thick specimens and under suitable welding conditions the defect free joints were made. The micro and macro structural analysis were performed. Mechanical tests have also been conducted to assess the tensile strength, joint efficiency, percentage of elongation and hardness of welded joints in various zones, i.e. weld nugget (WN), thermo-mechanical affected zone (TMAZ) and heat affected zone (HAZ). Micro Arc Oxidation (MAO) coating was done on the welded and base specimens to analyse the corrosion performance. The corrosion rates of coated (both base and welded) specimens were measured using salt spray test and the reduction in corrosion rates were identified after coating.