Wear and Corrosion Resistance of Decorative Oxide Layers Formed Thermally on Austenitic Steel

The article presents the results of tests of the functional properties of oxide layers produced on AISI 316L austenitic steel in an air atmosphere at three different temperatures (400 °C, 450 °C and 500 °C). X-ray diffraction showed that the formed phases, after all variants of oxidation, were Fe2O3, Cr1.3Fe0.7O3. Low peak intensity indicates that the formed layers are very thin, but despite this they influenced the functional properties of the steel. The best properties were characterized by steel subjected to oxidation at 400 °C. Layers obtained at a higher temperature did not give better results compared to steel without layers. Microhardness tests showed that the process increased hardness only at lower in-denter loads, which is another confirmation of the very low thickness of the layers. The greatest increase in hardness was observed for the sample oxidized at the lowest temper-ature. Tests performed using an optical profilometer showed a tendency for surface roughness to increase with increasing oxidation temperature. Low surface roughness, increased microhardness and low coefficient of friction resulted in steel oxidized at 400 °C obtaining the definitely lowest wear rate in the „ball-on-disc” test. The contact angle for each of the tested samples indicated hydrophilic properties. In turn, corrosion tests showed a deterioration in the corrosion resistance of the steel after oxidation at 450 °C and 500 °C. Oxidation at 400 °C did not cause a significant decrease in pitting corrosion re-sistance, while an increase in polarization resistance and a decrease in corrosion current density were observed.