Acta Metallurgica Sinica (English Letters) ›› 2023, Vol. 36 ›› Issue (5): 803-813.DOI: 10.1007/s40195-022-01503-6

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Effect of Grain Size and Compression Direction on the Hot Deformation Characteristics of High-Cr Ultra-Super-Critical Rotor Steel with Columnar Grains

Yanyang Wu1,3, Qiaodan Hu1(), Zongye Ding2(), Jianguo Li1   

  1. 1Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
    2School of Mechatronic Engineering and Automation, Foshan University, Foshan, 528225, China
    3WuYang Iron and Steel, Wugang, 450000, China
  • Received:2022-07-29 Revised:2022-10-08 Accepted:2022-10-18 Online:2022-12-13 Published:2022-12-13
  • Contact: Qiaodan Hu, Zongye Ding

Abstract:

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.

Key words: High Cr ultra-super-critical rotor steel, Solidification, Hot deformation, Dynamic recrystallization, Critical stress