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This paper presents the results of diagnostic examinations conducted on the coils of super-heaters made of 10CrMo9-10 steel that were operated in industrial conditions at 480°C for 130 thousand hours. The tube was exposed in a coal-fired boiler. The chemical and phase composition of the oxide/deposit layers formed on both sides of the tube walls (outside - flue-gas side and inside - steam side) and their sequence was examined using optical microscopy, scanning electron microscopy with electron backscatter diffraction and energy-dispersive X-ray spectroscopy, and X-ray diffraction. The changes in the mechanical properties caused by corrosion and aging processes were concluded from the hardness measurements. In addition, the nature of cracks in the oxide layers caused by pressing a Vickers indenter was determined. The results of these examinations have shown a high degradation of steel on the flue-gas inflow side and identified the main corrosion products and mechanisms. Abstract. This paper presents the results of diagnostic examinations conducted on the coils of super-heaters made of 10CrMo9-10 steel that were operated in industrial conditions at 480°C for 130 thousand hours. The tube was exposed in a coal-fired boiler. The chemical and phase composition of the oxide/deposit layers formed on both sides of the tube walls (outside - flue-gas side and inside - steam side) and their sequence was examined using optical microscopy, scanning electron microscopy with electron backscatter diffraction and energy-dispersive Xray spectroscopy, and X-ray diffraction. The changes in the mechanical properties caused by corrosion and aging processes were concluded from the hardness measurements. In addition, the nature of cracks in the oxide layers caused by pressing a Vickers indenter was determined. The results of these examinations have shown a high degradation of steel on the flue-gas inflow side and identified the main corrosion products and mechanisms. [ABSTRACT FROM AUTHOR]

The article discusses a study of the stacking fault (SF) microstructure model of ε-martensite and the application of the model in the DIFFaX computer program routine. The study used transformation-induced plasticity (TRIP) steel with chromium (Cr), manganese (Mn), nickel (Ni), silicon (Si), molybdenum (Mo), carbon (C) and nitrogen (N). A Bragg-Brentano diffractometer was employed to conduct X-ray diffraction (XRD) experiments. Transmission electron microscopy (TEM) validated the model.

The stress–strain behavior of austenitic steels showing the TRIP/TWIP effect can be adjusted in a broad range by the addition of suitable alloying elements. Although the underlying deformation mechanisms are reasonably understood, the existing models often fail, in particular when the density of microstructure defects is high and when individual microstructure defects and features start to interact. For a micromechanical description of the material behavior involving possible interactions between different microstructure defects in austenite (dislocations, stacking faults) and newly developed phases, a detailed in situ microstructure characterization of the material under load is needed. In this study, the in situ experiments are performed using synchrotron diffraction during uniaxial compression. The materials under study are Cr–Mn–Ni steels with different Ni contents (3, 6, and 9 wt%) and thus different stacking fault energies (7.5, 16.7, and 24.3 mJ m−2). The in situ measurements reveal information about the martensitic phase transformations and about the development of the defect structure of austenite. The latter is concluded from the broadening and shift of diffraction lines and interpreted in terms of the squared microstrain, which is proportional to the dislocation density, and the stacking fault probability. The changes in the phase composition and defect structure are correlated with the residual elastic lattice strain. [ABSTRACT FROM AUTHOR]

Abstract Rutile coatings deposited on corundum substrates are considered as promising functional elements improving the efficiency of the filtration of oxide inclusions out of aluminium melts. This contribution describes the reactions between rutile and two kinds of the aluminium melts and discusses the consequences of these reactions for the filtration process. It was found that the contact of rutile coatings with molten aluminium leads to the formation of a corundum layer at the solid/liquid interface. The exposure of the rutile coatings to molten AlSi7Mg0.6 alloy produces an interface layer of MgTiO 3. The interface layers possess defined orientation relationship to rutile which is characteristic for locally heteroepitaxial growth. The density functional theory calculations revealed that the TiO 2 /α-Al 2 O 3 and TiO 2 /MgTiO 3 interfaces with the orientation relationships observed experimentally have low interface energies. The mechanisms of the interface layer formation and the impact of these layers on the degradation of the rutile coatings are discussed. [ABSTRACT FROM AUTHOR]