Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel (named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX...

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Bibliographic Details
Published in:Acta metallurgica sinica : English letters 2019-04, Vol.32 (4), p.517-525
Main Authors: Liu, Peng, Chu, Zhao-Kuang, Yuan, Yong, Wang, Dao-Hong, Cui, Chuan-Yong, Hou, Gui-Chen, Zhou, Yi-Zhou, Sun, Xiao-Feng
Format: Article
Language:English
Subjects:
Aging
Aging (metallurgy)
Alloys
Carbides
Characterization and Evaluation of Materials
Chemistry and Materials Science
Corrosion and Coatings
Corrosion resistance
Creep rupture strength
Grain boundaries
Grain size
Heat resistant steels
High temperature
Materials Science
Mechanical properties
Metallic Materials
Microscopy
Microstructure
Morphology
Nanotechnology
Organometallic Chemistry
Oxidation
Power plants
Room temperature
Rupture tests
Solid solutions
Solution heat treatment
Spectroscopy/Spectrometry
Steel
Temperature
Tensile strength
Tensile tests
Tribology
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Summary:The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel (named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX . Subsequent aging treatment causes the precipitation of M 23 C 6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M 23 C 6 carbides changes from semi-continuous chain to continuous network. Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M 23 C 6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.
ISSN:1006-7191
2194-1289
DOI:10.1007/s40195-018-0770-0