OXIDATION OF AN AUSTENITIC STAINLESS STEEL PIPE CONTAMINATED BY PETROLEUM PRODUCTS

摘要

The experimental researches of this paper were carried out in order to investigate the characteristics of the oxide layers obtained on the internal and external surfaces of an austenitic stainless steel pipe. The external surface did not present any corrosion results but the internal surface of the analysed pipe was contaminated by sulphur during the transportation of petroleum products. In spite of this fact it was found that the mechanical properties of such a surface can be improved by air oxidation. The surfaces were investigated by Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analysis. Also the microidentation hardness was measured, on the both surfaces and between them, in order to detect and verify the improvement of the mechanical properties. Therefore it was found that oxidation at lower temperatures (300°C) resulted in formation of harder coatings. For comparison and better interpretation this paper presents the results of the analysis and measurements performed before and after the oxidation and cleaning, demonstrating the effectiveness of this simple method of reconditioning.