Investigation on corrosion behaviour of butt welded En-8 steel

Structural components fabricated from carbon steels such as EN- 8 are widely employed in engineering applications where they are frequently exposed to corrosive environments. The present investigation focuses on evaluating the corrosion behaviour of butt-welded EN-8 steel joints when subjected to different corrosive media. Three representative environments were selected for this study: 1 M hydrochloric acid (HCl) simulating an industrial acidic condition, synthetic seawater representing marine exposure, and distilled water serving as a neutral environment. Arc welding was employed to fabricate butt joints using E7018 electrodes under controlled parameters. The specimens were exposed to the respective corrosive environments for predetermined time intervals, and the corrosion rates were determined using the weight loss method. Microstructural characterization was performed to analyse the corrosion morphology across the weld zone, heat-affected zone (HAZ), and base metal, while microhardness testing was carried out to assess the degradation in mechanical properties. Results revealed that the corrosion rate was highest in 1 M HCl, moderate in seawater, and negligible in distilled water. The HAZ exhibited the most pronounced corrosion attack owing to its heterogeneous microstructure and residual stresses developed during welding. A gradual stabilization of corrosion rate over time was observed, which may be attributed to the formation of a protective oxide film. Overall, the study highlights that acidic environments significantly accelerate the corrosion of welded EN-8 joints, and careful consideration of operating environment is essential for prolonging the service life of welded components. These findings provide valuable insights for the design and maintenance of welded steel structures in industrial and marine conditions.