In-process volumetric sensing of defects in multiple parts during powder bed fusion using acoustics

Abstract

Additively manufactured (AM) metals have been gaining popularity due to their advantages over traditionally manufactured metals. AM processes can produce complex geometries unachievable in other methods. However, AM metals remain susceptible to traditional defects such as delaminations during manufacturing. Such defects can cause to build failure or loss of part integrity making them unsuitable for many structural applications. These defects often result from incorrect selections of process parameters for particular parts. In-situ monitoring systems using ultrasonic inspection have been proposed to sense and mitigate defects. This presentation describes experimental efforts to integrate a plurality of ultrasonic transducers into powder bed fusion AM. Nine 9Cr-1Mo stainless steel parts with identical dimensions were produced using powder bed fusion. Each part was printed with various laser power and speeds to produce a range of build qualities. Nine ultrasonic transducers were integrated into the build substrate to simultaneously monitor the nine AM parts during the build. Results of these measurements will be highlighted. This demonstration indicates the potential for using ultrasound to help determine optimal process parameters for reducing defects in AM parts. Additionally, this work supports progress toward closed-loop feedback for on-the-fly corrections.