A degradation mode of a carbon steel during thermal cycling under a simulated combustion environment

The degradation of A210C carbon steel has been investigated at 560 °C under a simulated coal-firing combustion environment. The simulation was performed by direct introduction into the chamber of flue gas from a freeboard of a coal-fired fluidized-bed combustor (FBC) and meanwhile by covering part of samples using ash deposits collected from the FBC freeboard wall. It shows that oxidation is significantly increased, when the steel is covered with ash deposits. During thermal cycling, the accelerated metal recession in the presence of deposits can be interpreted using a proposed degradation mode, which follows a sequence of scale wrinkling, buckling, and finally spalling. The effect of ash deposits on the steel degradation is also discussed.