Corrosion behavior of 304 stainless steel in the marine atmospheric environment of Xisha islands

The corrosion behavior and mechanism of 304 stainless steel exposed for different time periods in the marine atmosphere of Xisha islands were studied by scanning electron microscopy, energy dispersive spectra, electrochemical impedance spectroscopy, and Raman spectroscopy. Pitting corrosion is the main corrosion type of the steel in the atmospheric environment. The main compositions of the corrosion products are β-FeOOH, γ-Fe₂O₃, and Fe₃O₄. With the exposure time prolonging, the stability of the passive film deteriorates, the pitting number and depth increase, and the coverage of the surface corrosion products also enlarges. The pitting initiates more easily at scratches on the surface. The increase in machining precision of the surface will improve the pitting corrosion resistance.