Center-line-time functions and critical constants for predicting laser powder bed fusion melt pool distortion using one surface topography measurement

Published

September 21, 2023

Author(s)

Jesse Redford, Jason Fox, Christopher Evans, brigid mullany

Abstract

This work introduces a center-line-time function (CLTF) to characterize common scan strategies used in laser powder bed fusion (LPBF) that result in melt pool distortion. Eight rapid turnaround (RTR) samples, manufactured from nickel super alloy 625 using a commercial laser powder bed fusion machine with vendor-recommended build parameters, were utilized. The CLTF, in conjunction with a definition of melt pool distortion and a corresponding measurement procedure, was employed to evaluate the length of distorted melt pool regions in these samples. A critical time constant (CTC) was derived from the CLTF and measurement procedure, enabling the prediction of initiation, continuation, and termination locations of melt pool distortion for each sample geometry. Comparing the predicted and measured distorted melt pool lengths, an average error of 0.19 mm ± 0.77 mm was observed, with measured lengths ranging from 1.72 mm to 14.24 mm. The calculated CTC and CLTF values may vary depending on the material and machine parameters used for manufacturing the RTR samples. However, the methodology for determining the CTC and CLTF remains consistent, irrespective of material and machine parameters. These results demonstrate a step towards a quantitative procedure capable of characterizing the occurrence and location of melt pool distortion in both past and future builds. This approach provides practical insights that can aid in understanding and addressing melt pool distortion in laser powder bed fusion processes.

Proceedings Title

Proceedings of Joint Special Interest Group meeting between euspen and ASPE Advancing Precision in Additive Manufacturing

Conference Dates

September 19-21, 2023

Conference Location

Leuven, BE

Pub Type

Conferences

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Keywords

laser powder bed fusion, surface topography, melt pool distortion, swelling, superelevation, critical time constant, process qualification

Citation

Redford, J. , Fox, J. , Evans, C. and Mullany, B. (2023), Center-line-time functions and critical constants for predicting laser powder bed fusion melt pool distortion using one surface topography measurement, Proceedings of Joint Special Interest Group meeting between euspen and ASPE Advancing Precision in Additive Manufacturing, Leuven, BE, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956293 (Accessed April 28, 2024)