Salt spray or Salt fog test are commonly used and standardized method to test metal parts that will be exposed to marine conditions. Die cast Magnesium alloy plates of 3mm thick of AE42 grade are welded using advanced welding processes Friction Stir Welding (FSW). Mg alloys have received extensive recognition due to their excellent physical properties, including light weight, high strength/wt. ratio, high thermal conductivity and a good electromagnetic shielding characteristics, thus, become promising metal to replace steel and Aluminium alloys many structural and Mechanical applications due to their attractive mechanical and Metallurgical properties. The application of magnesium alloys used in automobile - Sport car wheels. From this research work, it is found that, in salt spray corrosion test, low corrosion rate is found at low concentrated solution and longer exposure time, and the corrosion morphology is predominantly influenced by the distribution of β- phase. This result shows the usage of the magnesium alloy for best environment and suitable applications from the aforementioned conditions.