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High/very-high fatigue properties and microstructure evolutions of 9Cr3W3Co turbine rotor steel at room temperature and 650 °C.
- Source :
-
Materials Science & Engineering: A . Oct2023, Vol. 885, pN.PAG-N.PAG. 1p. - Publication Year :
- 2023
-
Abstract
- The study aimed to investigate the high and very-high fatigue properties of 9Cr3W3Co turbine rotor steel at room temperature (RT) and 650 °C. The resulting S–N curves demonstrated a continuous downward trend, without exhibiting a conventional fatigue limit. The fatigue strength corresponding to 5 × 107 cycles is approximately 53.9% of yield strength at RT, increasing to around 55.4% at 650 °C. Meanwhile, compared to the fatigue strength at 5 × 107 cycles at RT, it at 650 °C decreased by 53.3%. Surface crack initiation was found to be the main fatigue fracture failure model, observed at both RT and 650 °C. Microscopic analysis revealed that severe dislocation motion and grain deformation occurred within the material matrix during the cyclic loading process at both RT and 650 °C, resulting in the formation of abundant low-angle grain boundaries, dislocation lines and sub-grains. At RT, the presence of the M 23 C 6 precipitated phase imposed a strong pinning effect, while the MX phase within the martensite laths effectively impeded the movement of dislocation lines, thereby enhancing fatigue properties. However, at 650 °C, the emergence of newly precipitated Cu-rich phases was observed, which can reduce the free path of dislocations, hinder slip motion of dislocations, and thus compensate for the negative effect caused by high-temperature microstructural degeneration. [ABSTRACT FROM AUTHOR]
- Subjects :
- *MATERIAL fatigue
*FATIGUE limit
*MICROSTRUCTURE
*STEEL
*CYCLIC loads
Subjects
Details
- Language :
- English
- ISSN :
- 09215093
- Volume :
- 885
- Database :
- Academic Search Index
- Journal :
- Materials Science & Engineering: A
- Publication Type :
- Academic Journal
- Accession number :
- 171992695
- Full Text :
- https://doi.org/10.1016/j.msea.2023.145605