Corrosion Behaviour of SMAW and GMAW Welded Mild Steel Attacked by Hydrochloride Acid

Corrosion is described as material’s destruction or deterioration because of reaction with its surrounding environment. This type of degradation represents a tremendous economic loss since so much value of loss being described. Mostly, in petroleum industry, mild steel are still the most commonly used metal to build structures. However, acid which is hydrochloric acid has been used as acidizing operation since its advantage over other mineral acid. This may cause mild steel structure susceptible to corrosion. This project is about the study of the rate of corrosion on SMAW and GMAW welded mild steel with different time of exposure. The comparison of f these two type of welded joint were subjected for microstructure analysis using SEM/EDX. Welded mild steel were prepared using SMAW and GMAW process with dimension of 100mm x 50mm x 6mm. Then, samples were inspected using NDT technique using magnetic particle testing. After that, the samples were immersed in 6 mol of HCl acid. Then, the corroded samples were cross-sectioned and were examined using SEM/EDX. The results show that, the rate of corrosion on SMAW welded mild steel is higher compared to the GMAW welded mild steel. As the duration of exposure increase, the weight loss also increased as well as the value of the corrosion rate. This results were supported by the MPT showing that the flaws and defects on the SMAW welded mild steel might be the cause that act as a stress raiser and thus, enhancing the corrosion degradation