Effects of tensile stresses on the oscillatory electrodissolution of X70 carbon steel in sulfuric acid solution

• The anodic dissolution of X70 steel/H2SO4 system is studied under various stresses.
• The elastic stress does not change the mode of the current oscillations.
• The plastic stress induces irregular current oscillations.
• Microplasticity occurs at the stress below the apparent yield strength.
• A micro-crack model is presented to explain the damage of the passive films.

Effects of elastic and plastic stresses on the oscillatory electrodissolution of X70 carbon steel have been investigated in 0.50 mol/L H2SO4 solution. The elastic stress increases the frequency of the current oscillations, while the plastic stress induces irregular oscillations. This fact suggests that the elastic and plastic stresses degrade the stability and increase the defects of the passive film to different degrees. Microplasticity occurs at the stress below the apparent yield strength and it exerts obvious effects on the oscillations. Finally, a micro-crack model is presented to explain the damage of passive films by the tensile stresses.