Enhanced Corrosion Phenomenon of SAPH440 Steels in 3.5wt.% NaCl Solution by Pre-strain Deformation Behavior

The influence of pre-strain deformation (PSD) behavior induced by plastic forming on the corrosion of SAPH440 steels in 3.5wt.% NaCl has been systematically investigated by weight loss test, corroded surface morphology observation, open circuit potential tests, electrochemical impedance spectroscopy measurements, and potentiodynamic polarization curve tests in the present work. All the results revealed that compared to the as-received specimens, both the corrosion rates and the susceptibility to pitting corrosion of the deformed specimens were increased by the PSD behavior. In addition, the yield strength (YS), the ultimate tensile strength (UTS), and the ratio of YS/UTS were also enhanced by PSD. The enhancements of the corrosion susceptibility and strengths were both closely relevant to the density and distribution of dislocations, which were well characterized by transmission electron microscopy (TEM).