Comparison of Surface Texture from Various Surface Morphology Techniques for Evaluating As-Built Ti6Al4V Laser Powder Bed Fusion

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Date

2023

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University of Texas at Austin

Abstract

Additive manufacturing (AM) is capable of creating unique and complex geometries that conventional methods cannot achieve. The applications for AM have been rapidly increasing across a variety of sectors, particularly for biomedical and aerospace components, the relatively low production volumes and high demand for customizability in both sectors are especially amiable to AM. However, without post-processing, AM components contain a variety of flaws, such as surface roughness and porosity, that can partially be mitigated by process parameters like scan speed and laser power. Surface roughness is a flaw present for every as-built AM surface that serves as an array of sites for every mode of material failure to occur. Common surface roughness measurements involve the use of optical and contact stylus profilometry. However, xray Computed Tomography (xCT) is already the most widely used method of analyzing AM parts for porosity, inclusions, and various other flaws. In terms of resolution, xCT should be fully capable of analyzing surface roughness and is the only method of the three investigated that can inspect interior geometries. Therefore, evaluating xCT as a fully inclusive analysis method for AM parts is advantageous. In this study, we compared three surface characterization technologies, xCT, optical profilometry, and contact stylus profilometry. The comparison of these technologies is being done on as-built Laser Powder Bed Fusion (L-BPF) Ti6AI4V fourpoint bending fatigue samples. Further understanding the difference among each of the technologies will aid ongoing research on developing a standard for xCT surface characterization while also providing more knowledge and insight into each technique and what can be expected. Each of the samples was produced by varying scanning speed and laser power, resulting in different surface textures. Preliminary results show deviations of Sa _%, Sz _%, Sv _%, and Sku _% between the xCT and optical microscopy methods are comparable between these two methods.

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