Internal surface roughness measurement of metal additively manufactured samples via x-ray CT: the influence of surrounding material thickness

Abstract

X-ray computed tomography (XCT) can be used to measure the internal and external surfaces of an object non-destructively and with micron-level spatial resolution. XCT is therefore an appealing method for measuring and characterising the internal surface roughness of additively manufactured parts that cannot be accessed by traditional tactile and optical surface roughness instruments. In this work, an additively manufactured aluminium spherical surface roughness sample is designed, fabricated and its surface roughness measured via a focus variation microscope, the sample is then XCT scanned when embedded in varying thicknesses of surrounding material. A quantitative and qualitative comparison between the optical and XCT surface roughness measurements is made; the results show that the Sa of the XCT-based surface roughness measurements increases as a function of surrounding material thickness.