Validation of a Microstructure-Based Model for Predicting the High Strain Rate Flow Properties of Various Forms of Additively Manufactured Ti6Al4V(ELI) Alloy

Abstract

To increase the acceptance of direct metal laser sintered Ti6Al4V(Extra Low Interstitial—ELI)in industry, analytical models that can quantitatively describe the interrelationships between themicrostructural features, field variables, such as temperature and strain rate, and the mechanical prop￾erties are necessary. In the present study, a physical model that articulates the critical microstructuralfeatures of grain sizes and dislocation densities for use in predicting the mechanical properties ofadditively manufactured Ti6Al4V(ELI) was developed. The flow stress curves of different microstruc￾tures of the alloy were used to obtain and refine the parameters of the physical model. The averagegrain size of a microstructure was shown to influence the athermal part of yield stress, while theinitial dislocation density in a microstructure was seen to affect the shape of the flow stress curve.The viscous drag effect was also shown to play a critical role in explaining the upturn of flow stressat high strain rates. The microstructure-based constitutive model developed and validated in thisarticle using experimental data showed good capacity to predict the high strain rate flow propertiesof additively manufactured Ti6Al4V(ELI) alloy.