Effects of initial δ phase (Ni3Nb) on hot tensile deformation behaviors and material constants of Ni-based superalloy
(1. School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China;
2. Light Alloy Research Institute, Central South University, Changsha 410083, China;
3. State Key Laboratory of High Performance Complex Manufacturing,
Central South University,Changsha 410083, China;
4. Key Laboratory of Efficient and Clean Energy Utilization,School of Energy and Power Engineering,
Changsha University of Science and Technology, Changsha 410114, China)
2. Light Alloy Research Institute, Central South University, Changsha 410083, China;
3. State Key Laboratory of High Performance Complex Manufacturing,
Central South University,Changsha 410083, China;
4. Key Laboratory of Efficient and Clean Energy Utilization,School of Energy and Power Engineering,
Changsha University of Science and Technology, Changsha 410114, China)
Abstract: Effects of initial δ phase (Ni3Nb) on the hot tensile deformation behaviors and material constants of a Ni-based superalloy were investigated over wide ranges of strain rate and deformation temperature. It is found that the true stress-true strain curves exhibit peak stress at a small strain, and the peak stress increases with the increase of initial δ phase. After the peak stress, initial δ phase promotes the dynamic softening behaviors, resulting in the decreased flow stress. An improved Arrhenius constitutive model is proposed to consider the synthetical effects of initial δ phase, deformation temperature, strain rate, and strain on hot deformation behaviors. In the improved model, material constants are expressed as the functions of the content of initial δ phase and strain. A good agreement between the predicted and measured results indicates that the improved Arrhenius constitutive model can well describe hot deformation behaviors of the studied Ni-based superalloy.
Key words: Ni-based superalloy; hot deformation; initial δ phase; constitutive model; material constants