Creep Mechanisms vis-à-vis Power Law vs. Grain Boundary Sliding in α-β Titanium Alloys for Physics Based Prognostics

This work is performed in support of our continued physicsbased prognostics system development using a life cycle management-expert system (LCM-ES) framework. The physical damage based modeling approach involving global behavior and localized response of a component at the microstructural level is used. The current research aims at constructing parts of a deformation mechanism map (DMM) for α-β Ti alloy. The appropriate constitutive equations are used for power law creep and grain boundary sliding mechanisms. Simulations are performed using the NewtonRaphson method using Matlab software code in order to obtain contour lines corresponding to strain rates ranging from 10 to 10 over the homologous temperature ranges of 0.10 to 0.655. The dominance of power law creep and grain boundary sliding over a wider range of stresses and temperatures in Ti-64 alloy is studied. The simulation results are validated using experimental data points. The predicted contour lines in the map match fairly well. The structurecreep mechanism relationships in α-β Ti alloy under different stress, temperature and strain rate conditions are discussed.