The effect of hydrostatic pressure on corrosion electric field considering the mechanochemical coupling effect

Abstract

In order to study the effect of hydrostatic pressure on the corrosion electric field of ship, the method of filling gas pressure with seamless steel cylinder was used to simulate the hydrostatic pressure on the submarine. The mechanochemical coupling model of corrosion electric field was established by using the solid mechanics and the current distribution (boundary element method, BEM) module in the COMSOL simulation software. The two physical fields were solved by using the sequential solver setup, and the structural stress simulated by the solid mechanics module was coupled to the expressions of equilibrium potential and exchange current density of electrode reaction, which were taken as the boundary conditions of the current distribution simulation module. Finally, the simulation results of the mechanochemical coupling model were compared with the measured corrosion electric field. The results show that the distribution characteristics of corrosion electric field and the variation trend of electric field with gas pressure obtained by simulation have a good agreement with the experimental results, moreover, the errors of peak-to-peak value of electric field obtained by experiment and simulation are within 20%, which demonstrates that the mechanochemical coupling model of corrosion electric field established in this paper can effectively predict the distribution characteristics of electric field under the synergistic action of stress and corrosion medium. When the gas pressure is 0 MPa, the maximum value of electric field modulus is 0.262 mV/m. When the gas pressure increases to 3 MPa, 6 MPa, and 9 MPa, respectively, the maximum value of electric field modulus correspondingly increases to 0.288 mV/m (9.92% increase), 0.317 mV/m (20.10% increase), and 0.348 mV/m (32.82% increase), therefore, the effect of stress on corrosion electric field cannot be neglected.