Characterization of the temperature evolution during high-cycle fatigue of the ULTIMET superalloy: Experiment and theoretical modeling

Abstract

High-speed, high-resolution infrared thermography, as a noncontact, full-field, and nondestructive technique, was used to study the temperature variations of a cobalt-based ULTIMET alloy subjected to high-cycle fatigue. During each fatigue cycle, the temperature oscillations, which were due to the thermal-elastic-plastic effects, were observed and related to stress-strain analyses. A constitutive model was developed for predicting the thermal and mechanical responses of the ULTIMET alloy subjected to cyclic deformation. The model was constructed in light of internal-state variables, which were developed to characterize the inelastic strain of the material during cyclic loading. The predicted stress-strain and temperature responses were found to be in good agreement with the experimental results. In addition, the change of temperature during fatigue was employed to reveal the accumulation of fatigue damage, and the measured temperature was utilized as an index for fatigue-life prediction.

Numerical Simulation on Rapid Evaluation of Fatigue Limit through Temperature Evolution

“…FL2 is in good agreement with not only the reference value but also Experimental data presents temperature slightly increases with loading amplitude before reaching a critical point beyond which temperature increases rapidly. The temperature rise before critical point is due to dissipation within elastic regime, that is due to viscosity (10) , discrete plastic deformation at disoriented grain-boundary (32), (33) and others. Because this elastic energy dissipation is neglected in the current numerical simulation, the hatched area in Fig.…”

“…Numerical simulation is a very good approach for this purpose. Jiang et al (10), (11) and Yang et al (12), (13) analyzed the temperature evolution during cyclic loading of Ultimet alloy by one-dimensional numerical simulation for some early cycles. However, to the authors' knowledge, there is no other researcher focuses on numerical simulation.…”

Temperature evolution and life prediction in fatigue of superalloys

“…[16] by the elastic modulus and adding Eq. [15], the total strain amplitude, ⌬/2, as a function of fatigue life is obtained as [18] Comparing Eq. [18] with the Coffin-Manson Equation, Eq.…”

“…[15], the total strain amplitude, ⌬/2, as a function of fatigue life is obtained as [18] Comparing Eq. [18] with the Coffin-Manson Equation, Eq. [1], the following results are obtained: [19] [20]…”

“…[18], the total strain amplitude, ⌬/2, as a function of fatigue life for ULTIMET alloy tested at room temperature is obtained as [25] The calculated fatigue life curves, based on Eq. [25] and the Coffin-Manson Equation, are shown in Figure 8.…”