High-Energy X-ray Tomographic Analysis of Precursor Metal Powders (Ti-6Al-4V) Used for Additive Manufacturing
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High-Energy X-ray Tomographic Analysis of Precursor Metal Powders (Ti-6Al-4V) Used for Additive Manufacturing Chihpin Andrew Chuang, Syed Saahir Shahab Ahmed, Peter Kenesei, Jonathan Almer, and Dileep Singh Submitted: 22 March 2020 / Revised: 21 October 2020 / Accepted: 7 November 2020 We used high-energy x-ray tomography to characterize Ti-6Al-4V metal powders (both as-received and recycled) used in powder-bed additive manufacturing process. The image processing workflow was developed to process and analyze large amount of data objectively by computer program. The distribution of size and shape of the metal particles as well as defect (mainly porosity) inside the particles was analyzed with the statistical representation and resolution in micrometer. The result revealed that circular-shaped porosity with various sizes could be embedded in the powder particles. These porosities could potentially be transferred to the 3D printed part and critically affect the mechanical performance of the component. The present study shows the effectiveness of characterizing metal powders using x-ray imaging techniques where sufficient number of particles can be sampled within tens of minutes with a minimum sample preparation and high accuracy. Clear structural differences in the as-received and recycled powders were delineated that helps in determining the feasibility of using the recycled powders. Keywords
additive manufacturing, advanced characterization, x-ray tomography
1. Introduction Additive manufacturing (AM) is the process of growing materials layer by layer to produce 3D objects derived from computer-aided design (CAD). More and more industries are seeing the benefits of AM due to the savings in time and cost, and higher productivity it can yield. This is reflected by increased investments in recent years from both the government and industry, and the explosive number of research papers from academia (Ref 1-4). While plastics were the original AM materials, metal components are increasingly significant in AM target areas. Powder-bed fusion techniques are one of the major branches of AM methods to print metal parts. The methods involve selective melting of metal powders by a heating source (laser or e-beam) in 2D; then, the layers are stacked sequentially to build a 3D object. Since the metal parts are made layer by layer in the AM process, materials undergo a rapid melting and quenching process in localized areas. This can create microstructural features not seen in traditionally processed materials including defects (e.g., pores) and wide grain size and texture distributions along with residual Chihpin Andrew Chuang, Peter Kenesei, and Jonathan Almer, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; Syed Saahir Shahab Ahmed, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; and Department of Electrical Engineering, The Pennsylvania State University, 207 Electrical Engineering West, University Par
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