Hydrostatic pressure was one of the critical factors affecting deep-sea corrosion. Theoretical research showed that increasing hydrostatic pressure could improve the activity of metal materials, increase the difference in activity between coupled metal materials, and aggravate the galvanic corrosion. At present, there were many researches on the corrosion behavior of metallic materials under hydrostatic pressure, but there were few researches on the influence of hydrostatic pressure on the corrosion behavior of metal materials. Due to the requirements of structure and performance in the marine environment, equipment components with different electrochemical properties must be connected. In such a harsh environment, galvanic corrosion would obviously accelerate. Therefore, it was very necessary to study the galvanic corrosion behavior of metallic materials under the condition of the deep sea. Fe-based alloys and Al-based alloys have been widely used in the marine environment, and there have been many studies on corrosion of Fe-based alloys and Al-based alloys in the deep-sea environment. As a result of single composition and structure, taking ultra-pure Al and ultra-pure Fe as the research object, the influence of phase, inclusion and other factors on corrosion behavior under hydrostatic pressure could be avoided, which was helpful to clarify the influence of hydrostatic pressure on corrosion behavior of ultrapure Al coupled with ultra-pure Fe. The influence of hydrostatic pressure on the corrosion behavior of ultrapure Al coupled with ultrapure Fe was studied in 3.5%NaCl using electrodynamic polarization and electrochemical noise. The discrete wavelet transform was utilized to remove the direct current drift of noise signal, and then the stochastic analysis based on the shot noise theory was carried out. The Hilbert-Huang transform was utilized to analyze the time-frequency characteristics of the noise signal. The surface morphology of corrosion samples was observed by SEM. The pressure distribution was simulated by finite element method. The results showed that the ultrapure Al was self-passivation in 3.5%NaCl solution under different hydrostatic pressures, pitting corrosion occurred after coupling with ultrapure Fe. With the increase of hydrostatic pressure, the galvanic potential of coupled ultrapure Al and ultrapure Fe decreased gradually, and the galvanic current increased gradually. The increase of hydrostatic pressure accelerated the pitting generation rate of ultrapure Al in galvanic corrosion, but inhibited the growth probability of pitting corrosion and reduced the tendency of local corrosion. When hydrostatic pressure was atmospheric, pitting corrosion could expand along the horizontal and vertical directions. In the presence of hydrostatic pressure, pitting corrosion was easier to expand along the horizontal direction.
