Statistical Analysis of the Distribution of the Schmid Factor in As-Built and Annealed Parts Produced by Laser Powder Bed Fusion

Abstract

This study documents a systematic analysis of the global Schmid factor for differentdeformation mechanisms in α0/α and β-grains in different forms of direct metal laser sintered(DMLS) Ti6Al4V(ELI) based on EBSD data. A novelty of this study is the use of these data to calculatethe values of the Schmid factor and the subsequent determination of their distribution and frequency,which, when compared to the slip systems of crystal structures, helps in determining the favourableslip systems in play. Both retained β-grains and reconstructed prior β-grains were considered in thisanalysis. The reconstruction of the prior β-grains was executed using the Automatic Reconstructionof Parent Grain for EBSD data (ARPGE) program. The distribution of the global Schmid factorfor these Ti6Al4V phases was calculated using the MATLAB-based MTEX toolbox program. Thisanalysis of deformation modes in the α0/α-phase was based on a uniaxial load state acting on thex, y, and z axes, while only the load along the build direction (x-direction) was considered in theanalysis of deformation mechanisms in the β-phase of the alloy. The results of this study showedthat the DMLS build direction influenced the distribution of the global Schmid factor for the basalslip system of α0/α-grains in as-built specimens and those samples that were heat treated below theα→β transformation temperature.