Corrosion can be defined as the destructive attack of a metal through interaction with its environment. Different type of welding can be factors that contribute to the corrosion and erosion problems since this type of welding will lead the material to expose with the corrosion and erosion agents like salt, air , water and material composition, dissolved oxygen content in the fluid, pH and fluid’s velocity characteristics. Research was carried out in order to investigate the corrosion rate on mild steel at 3 different types of welding which are Gas Metal Arc Welding (GMAW), Flux Core Arc Welding (FCAW) and Submersible Arc after exposed in 3 types of solution; sea water, sodium chloride and reverse osmosis (RO). In each of the types of welding, the parameters were fixed that includes of current, voltage and speed of travel. Immersion and polarisation test using Gamry instruments test were conducted to distinguish the corrosion rate. Results showed SAW had a least corrosion rate than FCAW and GMAW and morphology transformation differences occur during the corrosion process.