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- Englisch (2) (entfernen)
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- 3D tomography (1)
- Grain boundary corrosion (1)
- High temperature corrosion (1)
- Internal oxidation (1)
- Oxidation (1)
- STEM (1)
- Steel (1)
- Sulfidation (1)
Organisationseinheit der BAM
T92 steel was oxidized at 650 °C for 1000 h in dry and wet oxyfuel gases. The microstructure of inner oxide layer was investigated using scanning transmission electron microscopy and energy dispersive spectroscopy on thin lamellas of oxide cross-sections. The oxides were composed of fine equiaxed grains and separated into Fe-rich and Cr-rich regions. Fe-rich regions were wustite and iron sulphide while Cr-rich regions consisted of Fe-Cr spinel with different stoichiometries. Precipitates of (W,Mo)-rich oxides were formed within the oxide scale and beneath the oxide/alloy interface. Often iron sulphide and (W,Mo)-rich oxide were surrounded by Cr-rich spinel.
Ferritic alloys containing Cr form Cr5S6 precipitates along grain boundaries in hot SO2 environment. Grain boundary precipitates may influence the steel’s mechanical behavior. Cr5S6 precipitates were reconstructed three-dimensionally using FIB tomography analysis to determine the volume, number, and penetration depth. The volume growth of Cr5S6 precipitates increased only for the initial aging time of 3 h but became constant after 6 h. The number of precipitates increased linearly.