Numerical Simulation of High Temperature Deformation Behavior of Nickel-Based Superalloys Using Crystal Plasticity Models and Finite Element Method

Abstract

Development of reliable computational models to predict the high temperature deformation behavior of nickel based super-alloys is in the forefront of materials research. These alloys find wide applications in manufacturing of turbine blades and discs of aircraft engines. The micro-structure of these alloys consists of the primary gamma-prime phase and the secondary and tertiary precipitates (of Ni3Al type) are dispersed as gamma-prime phases in the gamma-matrix. It is computationally expensive to incorporate the explicit finite element model of the micro-structure in a crystal plasticity based constitutive framework to simulate the response of the polycrystalline micro-structure. Existing models in literature do not account for these underlying micro-structural features which are important for simulation of polycrystalline response. The aim of this chapter is to present a physically-motivated multi-scale approach for simulation of high temperature response of Nickel-based super-alloys. At the lower length scale, a dislocation density based crystal plasticity model is developed which simulates the response of various types of micro-structures. The micro-structures are designed with various shapes and volume fractions of gamma-prime precipitates. A new model for simulation of the mechanism of anti-phase boundary shearing of the gamma-prime precipitates, by the matrix dislocations, is presented in this chapter. The lower scale model is homogenized as a function of various micro-structural parameters and the homogenized model is used in the next scale of multi-scale simulation. In addition, a new criterion for initiation of micro-twin and a constitutive model for twin strain accumulation are developed. This new micro-twin model along with the homogenized crystal plasticity model has been used to simulate the creep response of a single crystal nickel-based super-alloy and the results have been compared with those of experiment from literature. It was observed that the new model has been able to model the tension-compression asymmetry as observed in single crystal experiments.