High Temperature Corrosion Behaviour of 20MnMoNi55 and AISI 304 Bare Steel in 75wt.%Na2SO4+25wt.%K2SO4 Molten Salt Environment at 900°C

Abstract

The oxidation behaviour of 20MnMoNi55 and AISI 304 Steel in Salt solution of 75wt.%Na2SO4+25wt.%K2SO4 has been studied at a temperature of 900°C under cyclic condition. Thermogravimetric technique has been used to know the corrosion kinetics of 20MnMoNi55 steel and AISI 304 steel in salt at 900°C under cyclic conditions for 50 cycles. Each cycle consisted of 1 hour heating at 900°C followed by 20min of cooling in air. 20MnMoNi55 steel sample followed somewhat linear rate of oxidation with more weight gain while AISI 304 sample followed the parabolic rate law of oxidation with less weight gain. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray (SEM/EDAX) techniques were used to characterise the oxide scales. AISI 304 steel was found to be more corrosion resistance than 20MnMoNi55 steel under salt oxidation for 50 cycles.