Investigation on Stress Corrosion Cracking Behavior of Welded High Strength Low Alloy Steel in Seawater Containing Various Dissolved Oxygen Concentrations

摘要

In this report, the susceptibility to stress corrosion cracking of welded high strength low alloy (HSLA)steel, immersing in seawater with different dissolved oxygen (DO) concentrations at 5with thepotential of -1.2 V, was investigated by slow strain rate test (SSRT). The SSRT results indicate thatthere is a lower elongation and percentage reduction in area with lower DO concentration. Fracturesurface morphology showed that quasi-cleavage fracture and short necking appeared at higher DOlevel, which was revealed by scanning electron microcopy (SEM) and optical microscopy. Thepolarization resistance reduced during the SSRTs with an increase in DO concentration of seawater,using electrochemical impedance spectroscopy (EIS). It is illustrated that the SCC susceptibility ofwelded HSLA steel increases with the increment of DO concentration in seawater, because higher DOcontent enhances the oxygen reduction reactions on metal surfaces and accelerates the metal anodicdissolution rate at the crack tips and on crack walls.