A Numerical Implementation of a 3D Crystal Plasticity Model for Directionally Solidified Ni-Based Superalloy

摘要

Directionally solidified (DS) Ni-based superalloys are extensively used in applications such as turbine blades that require a material with high strength, good creep, and fatigue and corrosion resistance, even at elevated temperature. In this paper, a 3D continuum crystal plasticity model is used to simulate the DS Ni-based superalloy, with application to uniaxial loading in the longitudinal and transverse orientations. Under the Arso (1983) crystal plasticity framework, the constitutive model invokes the kinematic hardening rule, and the yield criterion and flow rule are built on individual slip systems. Compared with the experiment date, we found that this model was able to accurately describe the stress-strain response undergo uniaxial loading, and could also capture the the Bauschinger effect of the cyclic plastic deformation of the DS Ni-base superalloy. In order to implement the constitutive model in the FEM, we use three integration methods, namely, the explicit /semi-implicit and fully implicit integration scheme, and all of them are base on the current configuration and updating the slip increment on each slip system. We have compared the three integration methods’ stability, convergence and effective. The constitutive model is implemented as a user material subroutine (UMAT) in ABAQUS and use a trial-and-error approach to estimate the material constant.