Microstructure Evolution and Coordinated Deformation of the 40Cr/Q345B Bimetallic Ring Blank at High Temperature

• Published in: Metals and materials international Vol. 30; no. 7; pp. 1997 - 2011
• Main Authors: Jia, Yanlong, Qi, Huiping, Liang, Youwen, Li, Zhenjiang, Bian, Zhuo
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 2024; Springer Nature B.V
• Subjects: Bimetals; Blanks; Centrifugal casting; Characterization and Evaluation of Materials; Chemistry and Materials Science; Deformation; Deformation effects; Deformation mechanisms; Dynamic recrystallization; Engineering Thermodynamics; Evolution; Grain orientation; Grain size distribution; Heat and Mass Transfer; High temperature; Hot pressing; Machines; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Metallic Materials; Microhardness; Microstructure; Processes; Solid Mechanics; Strain rate; Strengthening; Work hardening; Grain orientation spread; Dynamic recrystallization; 40Cr/Q345B bimetallic ring blank; Microstructure evolution; Coordinated deformation
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-023-01604-6

The evolution of microstructure has a significant impact on the coordinated deformation of bimetallic materials at high temperatures. This study conducted hot compression experiments on the 40Cr/Q345B bimetallic ring blanks. Based on EBSD measurement data, the parent austenite was reconstructed, and the dynamic recrystallization (DRX) fraction was evaluated using a grain orientation spread method. The DRX evolution of bimetallic ring blanks during hot deformation was studied, and the effects of different deformation conditions on the microstructure, microhardness, and interface element diffusion were analyzed. The coordinated deformation mechanism of the bimetallic ring blank at high temperatures was investigated. The results indicate that the 40Cr/Q345B bimetallic ring blank produced by centrifugal casting formed a 4.2 mm thick bonding layer (BL), with a smooth transition of elements, microstructure distribution, and grain size. The DRX evolution of 40Cr, BL, and Q345B was not synchronized, and the DRX of 40Cr occurred earlier with stable deformation. Q345B had a lower degree of DRX and a tendency of localized flow. The evolution of the BL approached 40Cr. When the strain reached 0.69, the DRX volume fractions of 40Cr, BL, and Q345B were 88.25%, 81.9%, and 53.77%, respectively. At higher temperatures and lower strain rates, the average grain sizes of 40Cr, BL, and Q345B were 150.6, 139.33, and 128.84 μm with severe grain coarsening. Coordinated deformation was enhanced by increasing the temperature and strain rate. Higher temperatures or lower strain rates increased the thickness of the metallurgical BL by promoting element diffusion. The synergistic strengthening effect of heterogeneous deformation induced strengthening and work hardening, combined with the DRX evolution gradient at the BL, played a coordinating role in the microstructure evolution of the bimetallic ring blank.
Graphical Abstract