PALAMARCIUC Ion Gheorghe Asachi Technical University of Iasi

Spoluautoři GALUSCA Dan-Gelu, ACHITEI Dragos, ISTRATE Bogdan, TUGUI Catalin-Andrei

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 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 thermal oxidation. For this all surfaces of the specimens were cleaned by sandblasting and ultrasonic cleaning. After that the specimens were heated in a tube furnace for 1 hour in continuous airflow. They were maintained at 300, 400, 500 and 600 °C. The surfaces were investigated by SEM, EDX and X-ray diffraction analysis. Also the microhardness was measured, on the both surfaces and between them, to detect and verify the improvement of the mechanical properties. Therefore it was found that the oxidation at lower temperatures 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, proving the effectiveness of this simple method of reconditioning.