9%Cr heat resistant steels: Alloy design, microstructure evolution and creep response at 650 °C
► 9Cr alloys with varying Ti and C contents were designed, produced and crept at 650 °C. ► Sub-grain and precipitate distribution and evolution investigated by STEM-HAADF. ► Correlations between microstructure evolution and mechanical properties were studied. ► Coarsening of sub-grain size was large...
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Published in | Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 528; no. 15; pp. 5164 - 5176 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Kidlington
Elsevier B.V
2011
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | ► 9Cr alloys with varying Ti and C contents were designed, produced and crept at 650
°C. ► Sub-grain and precipitate distribution and evolution investigated by STEM-HAADF. ► Correlations between microstructure evolution and mechanical properties were studied. ► Coarsening of sub-grain size was larger for Ti-containing 9Cr alloys. ► 9Cr alloy with low C and no Ti showed the highest creep strength of all studied alloys.
In this work 9%Cr alloys were designed supported by computational thermodynamic methods. Two sets of alloys were produced: 9%Cr alloys with 0.1%C and 0.05%C and 9%Cr alloys containing ∼0.03% Ti with 0.1%C and 0.05%C (always wt%). Microstructure investigations showed good agreement with the predicted phases of the thermodynamic modeling. The volume fraction of precipitated M
23C
6 carbides is directly related to the carbon content of the alloys. For Ti-containing alloys the precipitation of nano-sized Ti-rich MX carbonitrides was observed. The microstructure evolution (sub-grain and particle size) during creep at 650
°C/100
MPa was investigated by STEM-HAADF. The sub-grain size evolution and the coarsening of precipitates (MX carbonitrides, M
23C
6 and Laves phase) were more pronounced for Ti-containing alloys. 9Cr alloys without Ti and with low carbon content presented the highest creep strength of all investigated alloys. |
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ISSN: | 0921-5093 1873-4936 |
DOI: | 10.1016/j.msea.2011.03.037 |