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Creep Resistance and Microstructure Evolution in P23/P91 Welds
Vlastimil Vodárek1, Jan Holešinský2, Zdeněk Kuboň3
1Faculty of Materials Science and Technology, VŠB-Technical University of Ostrava, 17. listopadu 2172/15, 708 00 Ostrava, Czech Republic.
Materials (Basel, Switzerland)
|January 11, 2025
Summary
Investigating P23/P91 welds after creep exposure reveals that Weld A, using P91 filler, shows superior creep rupture strength. Failures predominantly occur in decarburized zones, with Laves phase precipitation observed.
Area of Science:
- Materials Science
- Metallurgy
- Creep Mechanics
Background:
- Heterogeneous P23/P91 welds are critical in high-temperature applications.
- Understanding creep behavior and microstructural evolution is essential for material integrity.
Purpose of the Study:
- To investigate the long-term creep performance of P23/P91 welds.
- To analyze microstructural changes and failure mechanisms under creep stress.
Main Methods:
- Creep rupture tests at 500, 550, and 600 °C.
- Microstructural analysis including EBSD (Electron Backscatter Diffraction).
- Kinetic and thermodynamic simulations of phase evolution.
Main Results:
- Weld A (P91 filler) exhibited higher creep rupture strength than Weld B (P23 filler).
- Failures concentrated in partially decarburized zones of P23/WM23 steel.
- Carburization in fusion zones, dissolution of carbides (M7C3, M23C6), and Laves phase (Fe2(W,Mo)) precipitation were observed.
- Partially decarburized P23 steel in Weld A demonstrated enhanced microstructural stability.
Conclusions:
- Filler material significantly impacts P23/P91 weld creep performance.
- Decarburization and Laves phase formation are key microstructural events influencing creep failure.
- Weld A offers better long-term creep resistance due to improved microstructural stability in affected zones.
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