Multi-Scale Crystal Plasticity FEM Approach to Modeling Nickel-Based Superalloys

Abstract

A hierarchical crystal plasticity constitutive model, comprising three different scales for polycrystalline microstructures of Ni-based superalloys, is developed in this paper. Specifically, an activation energy-based crystal plasticity (AE-CP) FEM model is developed incorporating characteristic parameters of the sub-grain scale γ γ ′ − morphology. A significant advantage of this homogenized AE-CP model is that its high efficiency enables it to be effectively incorporated in polycrystalline crystal plasticity FE simulations, while retaining the accuracy of detailed sub-grain level RVE models. Sub-grain level RVE models are created with explicit morphology, e.g. with variable volume fraction, precipitate shape and the channel-widths. The sub-grain crystal plasticity model incorporates a sizedependent dislocation density-based crystal plasticity model together with the mechanism of anti-phase boundary (APB) shearing of precipitates. The sub-grain model is homogenized for developing parametric functions of morphological variables in evolution laws of the AECP model. Micro-twinning initiation and evolution models are incorporated in the single crystal AE-CP finite element models for manifesting tension-compression asymmetry. In the next ascending scale, a polycrystalline microstructure of Ni-based superalloys is simulated using an augmented AE-CP FE model with micro-twinning. Statistically equivalent virtual polycrystals of the alloy CMSX-4 are created for simulations with the homogenized model. The results of simulations at each scale are compared with experimental data with good agreement.