The corrosion tests for HR3 Csteel used commonly in ultra supercritical unit boiler were carried out

in simulated flue/ash environments of firing high sulfur Liuzhi coal at 650 ℃ and 700 ℃.The fireside corrosion behavior and products formation mechanism were investigated

by corrosion kinetic curves

XRD

SEM

EDS and Raman analysis.The results indicate that

the fireside corrosion rate accelerated with the increasing temperature.The protective Cr_2O_3 and Fe_2O_3scales formed on the surface at 650 ℃.As the temperature increased

the structure of the oxide film varied from a single layer to double layers

with Fe rich in the outer layer and Cr rich in the inner layer.Low temperature hot corrosion occurred at 700 ℃

but the fireside corrosion rate was lower than the reported results.The HR3 Csteel had superior corrosion resistance at 700 ℃.