STRESS CORROSION CRACKING (SCC) OF LOW CARBON STEEL IN SELECTED ENVIRONMENTS

Abstract

This study has investigated the effect of various values of tensile stress on low carbon steel in different environments (1MH₂SO_4, 1MHCl, 1MNaOH and H₂O) where most conventional mild steels are normally exposed to while in service. The mild steel samples were pre-weighed and tensed in each of the environments with different stress values of 126.8N/m², 169.1N/m² 211.4N/m² and 253.6N/m² while the control sample was not tensed to any load. They were allowed to stand for 360 hours, with a set of samples from each environment withdrawn at intervals of 72hours for corrosion characterization.  The results obtained from all the environments studied showed that corrosion rate increased as values of stress increased. The sulphuric acid (H₂SO₄) environment recorded   the highest corrosion rate followed by hydrochloric acid (HCl) environment, while sodium hydroxide (NaOH) and water (H₂O) environments recorded the lowest values of corrosion rates at both low and high applied tensile stress levels. Applied tensile stress and corrosive environment were discovered to be the primary cause of stress corrosion cracking in mild steel but the full mechanism is not well understood  as the same applied stress could not induce corrosion in (NaOH) and water (H₂O) environments.