Investigation of the Corrosion Protection of Ni Deposition and Subsequent Annealing Temperature with Flow of Nitrogen on AISI 304 and AISI 316 Stainless Steels

AISI 304 (UNS S30400) and AISI 316 (UNS S31600) stainless steels were coated with a 250 nm Ni film by electron beam deposition and post-annealed at different temperatures with a flow of 600 cm³ min⁻¹ Ni. The samples were corrosion tested in 1.0 M sulfuric acid (H₂SO₄) solution using a potentiodynamic technique. Crystallographic and morphological structures of the samples were analyzed using x-ray diffraction (XRD) and atomic force microscopy (AFM), respectively, before corrosion testing and scanning electron microscopy (SEM) after corrosion testing. A clear correlation between the physical analyses (XRD, AFM, and SEM) and the potentiodynamic results was observed. Both surface roughness and the annealing temperature have an important role in the corrosion resistance of the samples. Optimum results can be obtained at 623 K for both AISI 304 and AISI 316 samples where both surface roughness and temperature (diffusion effect) have reached their critical values.