Oxidation Studies of T-91 and T-22 Boiler Steels in Air at 900°C

Abstract

The oxidation behaviour of T-91 steel and T-22 steel in air has been studied under isothermal conditions at a temperature of 900°C in a cyclic manner. Oxidation kinetics was established for the T-91 steel and T-22 steel in air at 900°C under cyclic conditions for 50 cycles by thermogravimetric technique. Each cycle consisted of 1 hour heating at 900°C followed by 20 min of cooling in air. T-91 steel sample followed somewhat linear rate of oxidation while T-22 sample followed the parabolic rate law of oxidation. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray (SEM/EDAX) techniques were used to characterise the oxide scales. T-91 steel was found to be more corrosion resistance than T- 22 steel in air oxidation for 50 cycles.