Numerical modeling of phase transformations of Ti6Al4V during electrical discharge machining

Abstract

Conventional machining of Ti6Al4V parts with complex shapes is often a tough task due to its low thermal conductivity and its high strength-to-density ratio. Thus, electrical discharge machining (EDM) comes as a better alternative that surpasses these manufacturing difficulties. In this work, a coupled thermo-mechanical model was built using the FEM software package Abaqus to estimate the sublayers final microstructure of a Ti6Al4V machined workpiece. The proposed numerical model aims to replicate a single-spark electrical discharge machining process. Phase transformations kinetic laws of the biphasic titanium alloy and heat flux distribution subroutines were implemented. XRD analysis, metallurgical sample preparation and optical microscope imaging were performed to investigate electrical discharge machining effects on Ti6Al4V part and to validate the numerical proposed model. Close agreement was found between experimental investigation results and numerical outcomes. The numerical model considers the remaining amount of 10% of β phase redeposited at the end of the discharge phase additionally to the martensitic phase α’.