Physics-based acoustic monitoring of keyhole regime transitions in laser powder bed fusion validated by operando synchrotron X-ray imaging - UTU Research Portal

A1 Refereed original research article in a scientific journal

Physics-based acoustic monitoring of keyhole regime transitions in laser powder bed fusion validated by operando synchrotron X-ray imaging;

Authors: Hamidi Nasab, Milad; Vaerenberg, Rik; Schlenger, Lucas; Van Petegem, Steven; Ganvir, Ashish; Rack, Alexander; Chen, Yunhui; Salminen, Antti; Marone, Federica; Aymanns, Florian; Gryllias, Konstantinos; Vrancken, Bey; Logé, Roland E.

Publisher: Elsevier BV

Publication year: 2026

Journal: Additive Manufacturing

Article number: 105299

Volume: 127

ISSN: 2214-8604

eISSN: 2214-7810

DOI: https://doi.org/10.1016/j.addma.2026.105299

Publication's open availability at the time of reporting: Open Access

Publication channel's open availability : Partially Open Access publication channel

Web address : https://doi.org/10.1016/j.addma.2026.105299

Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/526932201

Self-archived copy's licence: CC BY

Self-archived copy's version: Publisher`s PDF

Abstract

Additive manufacturing by Powder Bed Fusion using a Laser Beam on Metals (PBF-LB/M) enables unprecedented design freedom but remains limited by defect formation that stems from unstable melt pool dynamics. Current monitoring approaches often depend on machine learning, which can obscure the underlying physics and complicate industrial deployment. Here, a direct acoustic emission-based methodology is introduced that captures sound signatures of conduction-keyhole transitions and keyhole collapse. Using acoustic emission measurements validated by operando synchrotron X-ray imaging, a series of envelope-based indicators are established that robustly distinguish stable and unstable regimes in 316 L steel and Ti6Al4V under continuous and pulsed lasers. This physics-driven framework provides transparent, localized regime prediction, paving the way for more reliable and industrially scalable monitoring solutions in metal additive manufacturing.

Keywords:

acoustic emission monitoring, keyhole dynamics, Laser powder bed fusion, operando synchrotron x-ray imaging

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Funding information in the publication:
The authors would like to acknowledge the Paul Scherrer Institute, Villigen, Switzerland for provision of synchrotron radiation beamtime at the TOMCAT beamline X02DA of the SLS. This research was partially supported by Flanders Make, the strategic research center for the manufacturing industry via the MUSIC SBO project.
Furthermore, Dr. Schlenger and Prof. Logé would like to acknowledge the generous support of PX Group to the LMTM laboratory and together with Dr. Van Petegem they the support of the SMARTAM project from the Strategic Focus Area Advanced Manufacturing (SFA-AM), a strategic initiative of the ETH Board, Switzerland. In addition, Dr. Van Petegem would like to acknowledge the funding from the Swiss National Science Foundation (SNSF, grant No. 193799). Prof. Ganvir acknowledges the funding support from Tenure-Track grant to Prof. Ashish Ganvir; Research Council of Finland as well as European Council for co-funded M.ERANET 2022, GREEN-BAT (2022–2025) project and Research Council of Finland funded SOLACE, 360540 (2024–2028) project. Finally, Rik Vaerenberg would like to acknowledge the FWO SBO fellowship program (project number: 1SE9325N).