X-ray tomography for the advancement of laser powder bed fusion additive manufacturing.

Abstract

X-ray computed tomography is a powerful tool to nondestructively inspect additively manufactured parts. Additive manufacturing of metals, especially laser powder bed fusion, is increasingly being adopted for serial production of critical components in aerospace, automotive and various other industries. The technology holds huge potential for more efficient material usage and light weighting of components, among the many advantages. As this new production method is being ramped up and refined in various industry sectors, X-ray tomography is critical to the advancement of the quality of the produced components. X-ray tomography allows the nondestructive evaluation of the structural integrity of the parts produced, which in turn provides confidence in the expected performance of the parts. Besides final inspection of parts for porosity/defects and dimensional tolerances for a pass/fail decision, X-ray tomography also has a critical role to play in advancing and improving the additive manufacturing processes. This process improvement refers to the inspection of small representative coupon samples on a microscopic scale, in order to optimize the process parameters such as laser power, speed, scan strategy and various others. In this work, we describe the evaluation of small solid cube coupon samples and lattice structure coupon samples. These examples are meant to improve the understanding of the potential of X-ray tomography in advancing additive manufacturing processes (in contrast to its usual use for nondestructive testing of final parts), thereby providing support towards qualification of these processes and the parts produced in these processes. X-ray tomography, therefore, plays a key role in the adoption and qualification of high-quality metal additive manufacturing.