The characteristic of oxide scales on T91 tube after long-term service in an ultra-supercritical coal power plant

Oxidation behavior of HT9 steel in 700 °C – 900 °C steam

“…Exfoliation of the oxide layer depends on the stress state and relative strength of the oxide and oxide/metal interface. 11 Crack initiation and crack propagation result in two different types of spallation. The oxidation layer exfoliates due to non-penetrating longitudinal cracks in the oxidation layer, or it humps and bends until it breaks and exfoliates due to interface cracks between the steel matrix and the oxidation layer.…”

“…The voids may coalesce into a crack after a long exposure time. 9,11 Crack propagation leads to an exfoliation of the oxide layer. A breakdown of the oxide films can be seen in some regions.…”

“…Moreover, some defects, such as pores, voids and cracks, are present in the oxide layer. [9][10][11][12][13] The microstructures of the oxide and defects within the oxide layers depend on the exposure temperature and time. [8][9][10][14][15][16][17] Therefore, it is important to evaluate the oxidation behavior in the high-temperature steam for the nuclear fuel cladding materials.…”

A study of breakaway oxidation of 9Cr–1Mo steel in a Hot CO2 atmosphere using Raman spectroscopy

“…Equations (1) and (2) represent the processes of oxidation and carburisation respectively. Under certain conditions, oxidation can proceed rapidly, resulting in a thick oxide composed of multi-layered spinel and magnetite 13 . This breakaway oxidation is influenced by sample geometry and commonly occurs at sharp corners or edges.…”

Study of the Microstructural Evolution of Tempered Martensite Ferritic Steel T91 upon Ultrasonic Nanocrystalline Surface Modification

“…To provide pertinent combined properties under supercritical steam up to 650 o C, the microstructure of the materials should be composed of a ferritic matrix in martensite morphology with a large amount of phase boundaries, i.e., prior grain boundary (PAGB), lath boundary, subgrain boundary and second phase boundary (Panait et al, 2010;Rojas et al, 2011). In addition, the composition should contain high Cr to ensure high corrosion resistance and the precipitation of carbides (Chen et al, 2006;Shen et al, 2009;Zhong et al, 2012). Since the beginning of the twentieth century, researchers have conducted microstructural analyses pertaining to strengthening and degradation mechanisms using optical microscope (OM), scanning electron microscope (SEM), and transmission electron microscope (TEM).…”