38 J. Warner et al. Fig. 5.1 Dimensions of specimen Fig. 5.2 Machined specimen with paste and tape within the aerospace field. Recent work has shown hot isostatic pressing (HIPing) of Ti-6Al-4V reduces original diameter of void size, thus increasing AM material fatigue life by 20% [3]. Within this document, a porosity analysis has been conducted to examine the effects of the internal voids from a microscopic perspective. 5.1 Method Materials for testing were obtained from the Center for Design and Manufacturing Excellence (CDME) at The Ohio State University. Ten Ti-6Al-4V cylindrical rods, with a height and diameter of approximately 174 and 13 mm, respectively, were additively manufactured with a vertical build layout using GE Arcam Q10+ Electron Beam system. Built on 1 -mm-high supports, the cylindrical rods were randomly distributed throughout the build chamber. The processing parameters were standard OEM Ti-6Al-4V proprietary melt and support themes for control software 5.2.1. The +45-105μm recycled plasma atomized powder (AP&C) used for the build was all sourced from a singular lot with manufacturer reported chemistry; the number of powder reuses was not tracked (Fig. 5.1). The rods were machined to the specified parameters shown in Fig. 5.2 with the result shown in Fig. 5.3. CT scans were performed by the Air Force Institute of Technology (AFIT). Specimen labeled 07-TT had a voxel size of 16.49μm, and all other specimens reported had a voxel size of 14.911μm. The CT scanner used to obtain the image data sets was the Nikon XT H 225 ST, with the standard settings used. In order to properly orient CT data to DIC, silver conductive paste was applied to the radius of the specimen. Copper tape was applied to the bottom radius for precompensation of beam hardening. CT data was then post-processed in ImageJ, an open architecture software for image data manipulation and reconstruction. The CT slices within the gage section were evaluated and post-processed. Fatigue tests were performed using a 22-kip MTS load frame. Data acquisition for the force data was collected by a MTS FlexTest60 controller. Strain was measured with DIC, and force measurements were taken from the MTS system; this was synchronized to images via a NI USB DAQ model 6212.
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