The precipitation hardening stainless steels have high corrosion resistance and excellent mechanical strength. Passivation is the formation of a protective layer on the surface of the metal, this layer significantly influences the corrosion resistance of steel. Passivated 17-4PH martensitic stainless steel is used in various applications like oil field valve parts, chemical processes, aircraft accessories, reactor components, gears, among others. In this work 17-4PH was passivated on citric acid (C_6H_8O_7) at 15% and it was evaluated by electrochemical technique of potentiodynamic polarization (PP), it was exposed in Na_2SO_4 0.5M solution and adding H_2SO_4 in the solution to obtain different values of pH (2, 5, 8). Stainless steel 17-4PH, presented generalized corrosion, and shows passivation in a basic medium, while in acidic media it presented a tendency to passivation.
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