Investigation of Corrosion Rate for Different Type of Welding Joints using Shielded Metal Arc Welding (SMAW)

Corrosion is the deterioration of a metal as a result of chemical reactions between metal and its surrounding. Different type of metal and environmental condition, particularly gasses that are in contact with the metal, determine the rate of corrosion. Different type of welding joints can be factors that contribute to the corrosion problems since different type of welding joint normally exposed to the corrosion and erosion agents like salt, air, water, 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 joint which are butt joint, lap joint and edge joint after immersed in Sodium Chloride (NaCl), Hydrochloric acid (HCl), distilled water and natural sea water for 30 to 50 days. The mild steel was joined using Shielded Metal Arc Welding. For each of the welding joint the parameters were fixed which are current, voltage and speed of travel. Immersion and hardness test were conducted to distinguish the corrosion rate. Results shown butt joint suffered the highest corrosion rate than lap joint and edge joint and morphology transformation differences occur during the corrosion process.