LAUSR

ASTM F-139 surgical stainless steel was subjected to annealing treatments at 700 °C for different times. The effect of annealing on the chemical composition of the passive film was evaluated by x-ray photoelectron spectroscopy. The correlation of the surface chemistry with the corrosion behavior and semiconducting properties of the passive film was also investigated. Potentiodynamic polarization tests were conducted in phosphate-buffered solution at 37°C. The semiconducting character of the passive film was assessed by the Mott–Schottky approach. The microstructure of the annealed samples was characterized by optical microscopy. The grain size increased after annealing, but the differences between each annealing condition were not significant and could not be associated with the corrosion behavior of the annealed samples. The corrosion resistance was improved depending on the heat treatment condition due to compositional changes of the passive film upon annealing. The best corrosion properties were observed after annealing for 8 h which was ascribed to Cr2O3, MoO3 and FeO enrichment in the passive film.