401 / 2018-12-26 09:55:40

Studies on high temperature corrosion behavior of water wall materials at under cyclic temperature

high temperature corrosion; cyclic temperature; water wall materials; fragments; SEM&XRD

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As one of the components that are most prone to accidents, the failure of boiler water wall seriously affects operation security and efficiency of thermal power plants. The operation parameters of thermal power plants are not stable, and the thermal load tends to change with the change of demand. Therefore, the temperature of the water wall is not constant. The fluctuation of temperature will lead to the internal stress of the material or even internal cracks. The occurrence of cracks not only seriously affects the service life of the material, but also leads to more serious corrosion behavior and stress cracking problems. In this study, the corrosion behavior of water wall materials under cyclic temperature was studied. Corrosion products (XRD and EDS), corrosion morphology (SEM detection) and corrosion effects on residual matrix metal (SEM detection) were compared after different corrosion times to obtain the corrosion behavior under cyclic temperature conditions. There is no significant difference between the corrosion products of the sample at the circulating temperature and the corrosion products at the constant temperature. The corrosion surface layer is iron oxide, but according to the cross-sectional morphology it can be clearly observed that under the cyclic temperature condition, there is a certain increase in the corrosion layer thickness and the corrosion scales is broken with less protection. Hence, the corrosion layer is liable to fall off.