Oxidation of stainless was performed at 450 degrees C and oxygen partial pressures of 10(-9)-10(-4) Torr. Atomic force microscopy (AFM) images and surface-sensitive photoemission spectroscopy spectra clearly show that, at 450 degrees C, oxygen pressures lower than the critical pressure (p(c)(l)=similar to 1 x 10(-8) Torr) favor the formation of a smooth Cr2O3 oxide film whose AFM images clearly show a markedly smooth surface with no distinct grains. When oxidized at oxygen partial pressures higher than the critical pressure, the oxide film formed exhibits a rough surface with distinct grains that contain a significant amount of iron and manganese.