Effect of Chemical Passivation on Properities of S280 Ultra High-Strength Stainless Steel

The influence of chemical passivation parameters on the properties of S280 ultra high-strength stainless steel was studied by electrochemical polarization test to obtain optimal recipe. The passive film was characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to investigate the morphology and composition of the film respectively. The film performance including corrosion resistance, hydrogen embrittlement and fatigue were also tested. The results showed that processed by optimal recipe, the passive film was dense and composited of various metal oxides, hydroxides or oxyhydroxides, including oxide between different metals. The passivated S280 stainless steel was improved in corrosion resistance remarkably. The passivated S280 notched-bars pass 200 h tensile test without failure, meeting the hydrogen embrittlement requirement. Moreover, the fatigue property of passivated sample exhibited only a slight decline compared with bare sample.