In-Situ Characterization and Quantification of Melt Pool Variation under Constant Input Energy Density in Laser Powder Bed Fusion Additive Manufacturing Process


Size and shape of a melt pool play a critical role in determining the microstructure in additively manufactured metals. However, it is very challenging to directly characterize the size and shape of the melt pool beneath the surface of the melt pool during the additive manufacturing process. Here, we report the direct observation and quantification of melt pool variation during the laser powder bed fusion (LPBF) additive manufacturing process under constant input energy density by in-situ high-speed high-energy x-ray imaging. We show that the melt pool can undergo different melting regimes and both the melt pool dimension and melt pool volume can have orders-of-magnitude change under a constant input energy density. Our analysis shows that the significant melt pool variation cannot be solely explained by the energy dissipation rate. We found that energy absorption changes significantly under a constant input energy density, which is another important cause of melt pool variation. Our further analysis reveals that the significant change in energy absorption originates from the separate roles of laser power and scan speed in depression zone development. The results reported here are important for understanding the laser powder bed fusion additive manufacturing process and guiding the development of better metrics for processing parameter design.


Mechanical and Aerospace Engineering


This work is supported by Honeywell Federal Manufacturing & Technologies (FM&T, also known as the Kansas City National Security Campus), National Science Foundation , University of Missouri Research Board (UMRB) , Intelligent Systems Center at Missouri S&T , and Laboratory Directed Research and Development (LDRD) funding from Argonne National Laboratory , provided by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-06CH11357.

Keywords and Phrases

Additive manufacturing; Energy absorption; Laser powder bed fusion; Melt pool; X-ray imaging

International Standard Serial Number (ISSN)

2214-7810; 2214-8604

Document Type

Article - Journal

Document Version


File Type





© 2019 The Author(s), All rights reserved.

Publication Date

01 Aug 2019