Effect of Air Pre-Oxidation on High Temperature Air Oxidation Behavior of Carbon Steel and Stainless Steel

الملخص

In this paper, air pre-oxidation technique was
developed in order to improve the oxidation resistance of
carbon steel (0.131 wt% C) and stainless steel (304L). The
oxidation behavior of carbon steel and stainless steel
specimens with and without pre-oxidation was studied over
the temperature range 450 to 550°C for up to 120h. The
discontinuous oxidation behavior of the selected
experimental materials was tested in static air. The use of
pre-oxidation at 450°C for 5 hours to carbon steel and at
500°C for 5 hours to stainless steel showed considerable
improvements to the oxidation kinetics for both carbon steel
and stainless steel, especially at relatively low temperatures
– 450°C and 500°C. Generally, air oxidation kinetic data of
carbon steel showed rapid increase of weight compared with
stainless steel throughout the selected temperature range.
The formation of Cr2O3 layer improved the oxidation
resistance of stainless steel. Cr2O3 layer acts as a diffusion
barrier to the reactive species. Also, the oxidation process of
carbon steel was found to be controlled by the formation of
relatively thin and adherent layer of Fe2O3, especially at low
exposure temperature (e.g. 450°C). Whereas, at higher
temperatures (e.g. 550°C), the pre-formed Fe2O3 layer failed
to protect carbon steel from further oxidation even for short
exposure time. The scale formed on carbon steel at 550°C
severely cracked and spalled off especially, at places of
sample corners. Results of this research revealed that,
alloying elements in stainless steel were more beneficial to
oxidation resistance than pre-oxidation to steel, throughout
the whole range of time and temperature of this study.