Tracking Defects and Microstructural Heterogeneities in Meso-Scale Tensile Specimens Excised from Additively Manufactured Parts

Exp Mech. 2019;60(2):https://doi.org/10.1007/s11340-019-00558-4.

Abstract

The commercialization of additive manufacturing (AM) is underway in the aerospace and biomedical device industries [1, 2]. However, most metal parts produced by AM are limited to non-critical applications, since the various processes produce internal porosity, anisotropy, and microstructural heterogeneities [1, 3]. It has been implied that small-scale mechanical tests can advance measurement standards for AM applications by probing the effects of defects and heterogeneities on mechanical properties at more appropriate length scales [4, 5]. Traditionally, small-scale techniques have been used to characterize location- and orientation-specific mechanical properties in wrought materials [6-10]. A common method for excising mechanical test specimens from bulk parts with negligible influence on specimen integrity involves electrical discharge machining (EDM) [11]. This work demonstrates that excising meso-scale tensile specimens from additively manufactured parts enables tracking of sub-surface and visible features of interest (porosity and microstructural heterogeneities) throughout the entire gauge section such that the individual contributions to deformation behavior can be assessed.

Keywords: Additive manufacturing (AM); Electron backscatter diffraction (EBSD); Meso-scale; Tension test; Ti-6Al-4V; X-ray computed tomography (CT).