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Guss, G

Publications and source records attributed to Guss, G.

12 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Detecting keyhole porosity and monitoring process signatures in additive manufacturing: an in situ pyrometry and ex situ X-ray radiography correlation

Creation of pores and defects during laser powder bed fusion (LPBF) can lead to poor mechanical properties and thus must be minimized. Post-build inspection is required to ensure the printed parts contain acceptably low defect concentrations. These inspections are time consuming and costly, especially for large or complex parts. As a potential solution, in situ process monitoring can be used to detect the creation of defects, characterize local material behavior and predict expected component properties. However, the precise relationship between pore creation and in situ process monitoring still needs to be understood. In this work, high-speed infrared diode-based pyrometry and high-speed optical imaging signals were used to monitor LPBF printing of 446 stainless steel 316 L single tracks with varying laser power and velocity. Results indicate an increase in pyrometer signal and melt pool dimensions with increasing laser power and decreasing velocity in agreement with previous work. In addition, careful analysis of pyrometer signal reveals a distinct signature of the conduction-to-keyhole mode transition which was confirmed by metallography. Critically, pore defect initiation as characterized by ex situ X-ray radiography was correlated with in situ thermal monitoring signals to derive the probability of defect creation. Our results show that, in principle, a probabilistic prediction of pore formation can be achieved based on in situ high-speed pyrometry monitoring of the LPBF melt pool.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Comparison of ex situ x-ray radiography and in situ monitoring to gain control over defects during laser powder bed fusion

As in any other laser welding technique, creation of pores and defects during laser powder bed fusion can lead to component failure and thus cannot be tolerated. Post-build inspection is required to ensure the printed parts are defects-free. These inspections can take time and are complicated particularly for large parts. A solution is to use in situ process monitoring to detect the creation of defects, which could in turn be corrected during the printing itself. However, the relationship between pore creation and in situ monitoring still needs to be understood. In this work, we use x-ray computed tomography to detect pores and correlate them to pyrometry and high speed thermal imaging signals collected during laser welding.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Comparison of ex situ x-ray radiography and in situ monitoring to gain control over defects during laser powder bed fusion

As in any other laser welding technique, creation of pores and defects during laser powder bed fusion can lead to component failure and thus cannot be tolerated. Post-build inspection is required to ensure the printed parts are defects-free. These inspections can take time and are complicated particularly for large parts. A solution is to use in situ process monitoring to detect the creation of defects, which could in turn be corrected during the printing itself. However, the relationship between pore creation and in situ monitoring still needs to be understood. In this work, we use x-ray computed tomography to detect pores and correlate them to pyrometry and high speed thermal imaging signals collected during laser welding.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗