Abstract: The microstructure of the oxide scale contains a wealth of information about plane grain morphology and section structure. Research suggests that the exfoliation sensitivity is closely related to the microstructure of the oxide scale. Through the comparison between the oxide scale microstructures of various materials under different operating conditions (i. e. operation duration, temperature and mode)and chemical conditions, the embeddedness property of grain can be extracted from the grain type and size, column shaft and fancet of the planar grain morphology. The profile layer structure characteristics can be characterized by its thickness, delamination and void content. the combination of the two dimensional information can be integrated together to comprehensively determine the growth stage and exfoliation sensitivity, so as to provide decision-making basis for predicting and preventing the damage of the oxide.

Key words: utility boiler, high-temperature heating surface, steam oxide scale, microstructure, exfoliation sensitivity