Simulation of Material Stress–Strain Curve and Creep Deformation Response of Nickel Based Superalloys Using Crystal Plasticity Based Finite Element Models

Abstract

Development of reliable computational models at the micro-scale to understand the material deformation behavior has been gaining worldwide attention. These are increasingly being used in order to design new materials as well as characterize material behavior at different length scales. In this work, a microstructure-sensitive crystal-plasticity-based model has been developed in order to understand the deformation behavior of nickel-based superalloys at different temperature and stress levels. As the microstructure of these alloys consist of primary \( \gamma \) matrix with embedded secondary and tertiary \( \gamma^{\prime} \) precipitates, the stress–strain as well as the creep deformation behavior at different temperatures depend upon the micro-structural features. The mechanical and creep strength of these alloys are sensitive to volume fraction, shape and size of the precipitates and their resistance to the dislocation motion. All these strengthening features has been incorporated into a dislocation density based crystal plasticity model and implemented in a finite element code. The responses of different microstructures have been homogenized as a function of different geometrical features of the precipitates and their distribution in the matrix. The homogenized model has been used to simulate the stress–strain behavior of a nickel-based alloy single crystal at 800 °C as well as the creep strain versus time behavior at 700 °C and 820 MPa of axial stress. The results have been compared with experimental data. It has been concluded that a multi-scale approach is necessary in order to take into account of the micro-structural information in the deformation response of materials and the dislocation-density based model is suitable for such simulations. The model has also been able to simulate the tension–compression asymmetry in the creep-deformation behavior of single crystals as observed in experiments.