New Constitutive Model for Hot Deformation Behaviors of Ni-Based Superalloy Considering the Effects of Initial δ Phase

Abstract

The hot deformation behaviors of a typical Ni-based superalloy are investigated by uniaxial tensile tests over wide ranges of strain rate and deformation temperature. The experimental results show that the flow stress is sensitive to strain, strain rate, and deformation temperature. Especially, initial d phase (Ni 3 Nb) has a special effect on the flow stress. The initial d phase can enhance the work-hardening behavior and result in the increased peak stress at relatively small strains. With the further straining, the initial d phase can stimulate the dynamic recrystallization and promote the dynamic-softening behaviors. Considering the synthetical effects of deformation temperature, strain, strain rate, and initial d phase on the hot deformation behaviors, a new phenomenological constitutive model is proposed. In the proposed model, the peak stress and material constant are expressed as functions of Zener-Hollomon parameter and the initial content of d phase. A good agreement between the predicted and measured results shows that the proposed model can give an accurate and precise estimate of the hot deformation behaviors for the studied Ni-based superalloy.

Constitutive Model Based on Dynamic Recrystallization Behavior during Thermal Deformation of a Nickel-Based Superalloy

“…Ultimately, the deformation activation energy of the studied superalloy is estimated at 646.341 kJ/mol, which is close to the result (691 kJ/mol) of Yu et al [32]. In general, the combined effects of deformation temperature and strain rate on the forming performance of metals or alloys can be described by Zener-Hollomom (Z) parameter [33][34][35]. The function Z can be expressed as Equation (7): where Q is the aforementioned thermal deformation activation energy and n 2 is the material constant.…”

“…In general, the combined effects of deformation temperature and strain rate on the forming performance of metals or alloys can be described by Zener-Hollomom (Z) parameter [33][34][35]. The function Z can be expressed as Equation (7):…”

Modified Fields–Backofen model for constitutive behavior of as-cast AZ31B magnesium alloy during hot deformation

“…Because of the complexity of the model and the limitations of the forecasting range, the model could not be easily and precisely referenced in the FEM code for simulating forming processes. As a result, appropriate constitutive models based on strain rate, strain, and temperature should be put forward in new research for the representation of flow stress [27][28][29][30]. Hollomon constructed a relationship between flow stress and strain as σ = kε n , where k is the stress coefficient and n is the strain hardening coefficient [31].…”

Study of Flow Softening Mechanisms of a Nickel-Based Superalloy With Δ Phase

“…On the one hand, Lin et al [15,16,17], Kumar et al [18], Zuo et al [19], Yang et al [20], Azarbarmas et al [21], and Liu et al [22] developed various accurate constitutive models to predict the flow stress of some typical superalloys. Considering the synthetical effects of deformation temperature, strain, strain rate, and initial δ phase on the hot deformation behaviors of GH4169 superalloy, Lin et al [23,24] proposed the improved phenomenological constitutive model. In their proposed models, material constant are expressed as functions of the initial content of δ phase.…”