Crystal-plasticity modeling of monotonic and cyclic softening in inconel 718 superalloy

A phenomenological model is proposed to predict both monotonic and cyclic softening in Inconel 718 superalloy at 650 C. Contrary to the current cyclic softening models consisting of a modified isotropic hardening variable, an internal state variable acting on the amplitude of the back stress is proposed and implemented in a crystal -plasticity model. Crystal-plasticity finite-element simulations are performed to validate quantitatively the model on uniaxial strain-controlled monotonic and cyclic loading for several plastic strain rates and strain amplitudes as well as to gain insights on the ratcheting phenomenon depending on the mean stress and stress amplitude values when cyclic softening occurs.

Automated summary

A phenomenological model is proposed to predict both monotonic and cyclic softening in Inconel 718 superalloy at 650℃. Crystal-plasticity finite-element simulations are performed to validate the model and gain insights on the ratcheting phenomenon.