Effect of Grain Size and Compression Direction on the Hot Deformation Characteristics of High-Cr Ultra-Super-Critical Rotor Steel with Columnar Grains
- Resource Type
- Original Paper
- Authors
- Wu, Yanyang; Hu, Qiaodan; Ding, Zongye; Li, Jianguo
- Source
- Acta Metallurgica Sinica (English Letters). 36(5):803-813
- Subject
- High Cr ultra-super-critical rotor steel
Solidification
Hot deformation
Dynamic recrystallization
Critical stress
- Language
- English
- ISSN
- 1006-7191
2194-1289
The columnar grains with a duplex grain size distribution in the ingot increase the difficulty of the hot forging of the as-cast high Cr ultra-super-critical rotor steel. The hot deformation behaviors of the high Cr steel with different initial grain sizes under various compression directions were investigated. The results show that the hot deformation characteristic is strongly grain size and compression direction dependent. The finer grain size and compression direction perpendicular to the columnar grains increase the flow stress and activation energies of hot deformation, comparing with the large grain and deformation direction parallel to the columnar grains. The relationships between flow stress and deformation parameters for the different initial structures conform to the established constitutive equations. The former enhances the critical stress of the dynamic recrystallization (DRX), inhibiting the occurrence of DRX and reducing the dimensions of DRX grains.