The paper presents test results of the oxidation of P265 steel, taking into account the effect of the surface roughness. Isothermal oxidation was carried out in air in the temperature of 800 ˚C during 1, 5, 20 and 25 hours. It was found that the surface condition which was directly linked to the surface preparation is crucial for the adherence between the substrate and the scale, and the structure of the oxidation products layer.
Słowa kluczowe: oxidation, surface roughness, P265steel
W pracy przedstawiono wyniki badań utleniania stali P265 z uwzględnieniem wpływu chropowatości powierzchni. Izotermiczne utlenianie przeprowadzano w powietrzu o temperaturze 800 °C w czasie 1, 5, 20 i 25 godzin. Stwierdzono, iż sposób przygotowania powierzchni ma zasadnicze znaczenie dla przyczepności zgorzeliny z podłożem oraz wpływa na strukturę i budowę powstających produktów utleniania.
Keywords: utlenianie, chropowatość powierzchni, stal P265
The nature of the operation of power devices in high temperature conditions requires the use of top quality raw materials and the selection of the right grade of steel, because at elevated temperatures, the products are exposed to creep, relaxation, heat fatigue or accelerated corrosion . Therefore, they require the use of steel grades that meet the conditions in this respect. An important group of metal materials is steel designed to work at elevated temperatures, commonly referred to as boiler steels, which can be used under such conditions. The main applications are the machinery and equipment used in the power industry, such as boiler and turbine fittings, pressure vessels for the chemical or power industry, water turbines, steam and gas turbines . When selecting the steel grades, one must follow the requirements that apply to the quality of the parts and the correct use of the equipment under specific operating conditions. Besides, in case of the well-established steel grades, the use properties are determined by the technology of manufacturing of the steelmaking product as well as the technology of manufacturing of the given part of the device. It is important that these materials are characterized by high strength, durability and resistance to high temperature corrosion. An important aspect here is the way of preparing steel surfaces, which are going to be exposed to high temperatures . The oxidation of the steel triggered by high temperature causes the formation of scale, which is important in the operation of the structure, both in the aspect of the oxidation process and with respect to the adhesion of the scale to the surface of the steel. The adhesion of scale is dependent on many factors: the time and temperature of oxidation, the type of oxidizing atmosphere, and above all, the chemical composition and the steel structure. Apart from the above mentioned factors, the physicochemical state and surface microst [...]
 Hernas A., Dobrzański J. 2003. Trwałość i niszczenie elementów kotłów i turbin parowych, Monografia 2, Gliwice, Wydawnictwo Politechniki Śląskiej.  Hernas A., Wala T., Staszewski M. 2009. “Characteristic and selection of steels for superheaters with supercritical steam parameters". Inżynieria Materiałowa 30 (3): 143-151.  Małecka J. 2015. “The influence of the surface roughness on the oxidation behavior of Ti-25Al-12Nb alloy - surface layer characteristic". Ochrona przed Korozją (58) 3: 75-81.  Mrowec S., T. Werber. 1982. Kinetyka i mechanizm utleniania metali. Katowice, Wydawnictwo Śląsk  Pilling N., B. Bedworth. 1923. “The oxidation of metals at high temperatures". Journal of the Institute of Metals 29 : 529-534.  Wagner C. 1956. “Formation of composite scales consisting of oxides of different metals". Journal of the Electrochemical Society 103 (11): 627-633.  Wagner C. 1959. “Reaktionstypen bei der oxydation von legierungen". Elektrochemie 63: 772-782.