Contents lists available at ScienceDirect Materials Characterization journal homepage: www.elsevier.com/locate/matchar Effects of thickness and orientation on the small scale fracture behaviour of additively manufactured Ti-6Al-4V J. Dzugan a , R. Prochazka a , M. Rund a , P. Podany a , P. Konopik a , M. Seifi b, ⁎ , J.J. Lewandowski b a COMTES FHT, Dobřany, Czech Republic b Case Western Reserve University, Cleveland, OH, USA ABSTRACT The effects of sample location, orientation, and thickness on the microstructure and resulting tensile properties of miniature SLM and SEBM AM samples of Ti-6Al-4V has been determined. Microstructure and mechanical property variations in the miniature samples are shown to be related to build orientation and also partly to specimen thickness and position within the build chamber. The present work is our initial attempt to develop a systematic approach for characterization of the microstructure (including defects via tomography) and me- chanical properties on miniature AM test specimens that can also be used to reveal issues related to process stability (e.g. fluctuations in build conditions). The discussion is also included regarding their relevance to miniature samples that can be manufactured along with parts, excised from larger samples, and/or excised from actual manufactured components. 1. Introduction While additive manufacturing of metals has opened a completely new era in the field of production technologies and design freedom, extending its application to fracture-critical components will continue to require a more complete understanding of process-structure (in- cluding defects)-properties relationships than currently exists. Recent reviews [1,2] have highlighted issues related to microstructure and property variations within and between standard builds along with both location- and orientation-dependent properties in bulk standard- sized samples. Much less work has focused on similar characterization of actual as-deposited parts/components, although recent work has begun to reveal significant differences in microstructure/defect density along and between builds as well as effects of thickness/build dimen- sions on the resulting microstructures [3–12]. Other studies [5,8,13,14] have also investigated the effects of different sample geometries on resulting microstructure and mechanical properties. In order to fully realize the potential of AM and the accompanying design freedom with regard to component geometry, a more complete understanding of the process-structure (including defects)-properties relationships is needed. As an example, it is currently possible to utilize various shape/topology optimization schemes in order to reduce com- ponent weight and increase stiffness. However, this approach typically assumes isotropic material properties and may introduce gradients in wall thicknesses at various locations in the topologically-optimized part. The different nature of various AM techniques (e.g. PBF, DED) and the different build envelopes, Power-Velocity regimes, form of starting material, etc., typically produces both location- and orientation-de- pendent properties. These can arise from the different thermal histories experienced within and between builds of constant thickness. Changes in the build thickness (e.g. within a build or actual part) may introduce further differences in the local thermal history [3–8] and resulting microstructure if the process parameters cannot be adjusted inline to prevent them. Post-processing of such materials may or may not be effective in homogenizing the microstructure/defect differences created by such thermal variations. In any case, the effects of such variations on microstructure (including defects) and resulting properties must be addressed in a systematic manner in order to take advantage of existing and evolving AM processes, culminating in the eventual design of safer and more economic AM parts. One approach is to examine sub-sized non-standard specimens to rapidly evaluate the effects of changes in process parameters, sample thickness, location, and orientation on the resulting microstructures (including defects) and properties. Miniature samples may also be excised from various locations in as-deposited parts in order to directly document location- and orientation-dependent properties and this is the topic of ongoing efforts [15]. The usefulness of miniature witness samples deposited alongside parts depends on any differences in thermal history in such situations although it can provide https://doi.org/10.1016/j.matchar.2018.04.003 Received 20 October 2017; Received in revised form 19 February 2018; Accepted 3 April 2018 ⁎ Corresponding author. E-mail addresses: jdzugan@comtesfht.cz (J. Dzugan), radek.prochazka@comtesfht.cz (R. Prochazka), martin.rund@comtesfht.cz (M. Rund), pavel.podany@comtesfht.cz (P. Podany), pavel.konopik@comtesfht.cz (P. Konopik), mohsen.seifi@case.edu (M. Seifi), jjl3@case.edu (J.J. Lewandowski). Materials Characterization xxx (xxxx) xxx–xxx 1044-5803/ © 2018 Elsevier Inc. All rights reserved. Please cite this article as: Dzugan, J., Materials Characterization (2018), https://doi.org/10.1016/j.matchar.2018.04.003