A Two-Stage Physical-Based Model for Predicting Flow Stress of As-cast TiAl Alloy Under Hot Deformation Conditions
- Northwestern Polytechnical University, School of Materials Science and Engineering (China)
- The Hong Kong Polytechnic University, Department of Mechanical Engineering (China)
The hot deformation behavior of Ti-30Al-4.2Mn-4.5Nb-0.2B alloy was investigated using the isothermal compression experiment at temperatures of 1020-1200 °C and strain rates of 0.001-1 s{sup −1}. The flow stress was sensitive to the deformation parameters like temperature and strain rate, which decreases with the increase in temperature and decrease in strain rates. Based on the true stress-true strain data, a two-stage physical-based model was proposed to describe the flow stress curve of as-cast TiAl alloy during hot deformation process. For establishing the model, at first, the flow curves of dynamic recovery (DRV) were modeled by employing stress-dislocation relation and adjusting dislocation annihilation coefficient Ω. Then, the flow curves of dynamic recrystallization (DRX) were modeled by considering the dynamic softening behavior into Avrami equation. Finally, the flow curves in the entire deformation stages could be described by embedding the predicted data of DRV model (i.e., flow stress before the critical strain) into the predicted data by DRX model (i.e., flow stress after the critical strain). The critical strain for initiation of DRX was determined by the double-differentiation method. To evaluate the applicability and effectiveness of DRX kinetics equation, the DRX curves were calculated and were consistent with the microstructure observation. Comparison between the experimental and predicted data shows that the proposed physical-based model can well forecast the flow stress under a wide working domain.
- OSTI ID:
- 22863255
- Journal Information:
- Journal of Materials Engineering and Performance, Vol. 27, Issue 10; Conference: EUROMAT 2017: European Congress and Exhibition on Advanced Materials and Processes, Thessaloniki (Greece), 17-22 Sep 2017, AeroMat 2017: Advanced Aerospace Materials and Processes Conference and Exposition, Thessaloniki (Greece), 17-22 Sep 2017; Other Information: Copyright (c) 2018 ASM International; http://www.springer-ny.com; Country of input: International Atomic Energy Agency (IAEA); ISSN 1059-9495
- Country of Publication:
- United States
- Language:
- English
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