In situ measurements of layer roughness during laser powder bed fusion additive manufacturing using low coherence scanning interferometry

DePond, Philip J.; Guss, Gabe; Ly, Sonny; Calta, Nicholas P.; Deane, Dave; Khairallah, Saad; Matthews, Manyalibo J.

doi:10.1016/j.matdes.2018.05.050

Title: In situ measurements of layer roughness during laser powder bed fusion additive manufacturing using low coherence scanning interferometry

Abstract

Here, layer-to-layer height measurements of additively manufactured 316L stainless steel using high speed spectral-domain optical coherence tomography (SD-OCT) are presented. Layers are built up using an open architecture laser powder bed fusion machine while height measurements are made in-line along the process laser path following each layer print. Printed cubes, with and without an internal ‘overhang’ channel, were built to investigate the effect of scanning parameters on surface structure. Layer-to-layer scan rotation strategy significantly impacts surface roughness between layers which in turn can influence porosity. Spatter particles, which have been correlated with numerous defect modalities, generate high points in the powder bed and can persist on a melted surface for many layers. Laser power significantly affects overhang morphology, as measured by SD-OCT. Large dross occurs in the high energy density regime, while balling and a capillary-driven coalescence of unstable melt pools perpendicular to the scanning direction occurs in the low energy density regime. High fidelity powder-scale simulations of deep powder layers were used to further elucidate the underlying physics revealed by SD-OCT measurements and high speed imaging, yielding insight to defect formation mechanisms which can lead to improved process parameters.

Authors:

DePond, Philip J.; Guss, Gabe; Ly, Sonny; Calta, Nicholas P.; Deane, Dave; Khairallah, Saad;

Publication Date:: Wed May 23 00:00:00 EDT 2018

Research Org.:: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Org.:: USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program

OSTI Identifier:: 1438941

Alternate Identifier(s):: OSTI ID: 1459125

Report Number(s):: LLNL-JRNL-747073
Journal ID: ISSN 0264-1275; S0264127518304350; PII: S0264127518304350

Grant/Contract Number:: AC52-07NA27344; 15-ERD-037; 18-SI-003

Resource Type:: Published Article

Journal Name:: Materials & Design

Additional Journal Information:: Journal Name: Materials & Design Journal Volume: 154 Journal Issue: C; Journal ID: ISSN 0264-1275

Publisher:: Elsevier

Country of Publication:: United Kingdom

Language:: English

Subject:: 42 ENGINEERING; 47 OTHER INSTRUMENTATION; Additive manufacturing; Laser powder bed fusion; Selective laser melting; In situ process monitoring; Optical coherence tomography; Interferometry

Citation Formats


                    DePond, Philip J., Guss, Gabe, Ly, Sonny, Calta, Nicholas P., Deane, Dave, Khairallah, Saad, and Matthews, Manyalibo J. In situ measurements of layer roughness during laser powder bed fusion additive manufacturing using low coherence scanning interferometry.  United Kingdom: N. p., 2018. 
Web.  doi:10.1016/j.matdes.2018.05.050.

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                    DePond, Philip J., Guss, Gabe, Ly, Sonny, Calta, Nicholas P., Deane, Dave, Khairallah, Saad, & Matthews, Manyalibo J. In situ measurements of layer roughness during laser powder bed fusion additive manufacturing using low coherence scanning interferometry.  United Kingdom.  https://doi.org/10.1016/j.matdes.2018.05.050

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                    DePond, Philip J., Guss, Gabe, Ly, Sonny, Calta, Nicholas P., Deane, Dave, Khairallah, Saad, and Matthews, Manyalibo J. Wed .  
"In situ measurements of layer roughness during laser powder bed fusion additive manufacturing using low coherence scanning interferometry".  United Kingdom.  https://doi.org/10.1016/j.matdes.2018.05.050.

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@article{osti_1438941,

  title        = {In situ measurements of layer roughness during laser powder bed fusion additive manufacturing using low coherence scanning interferometry},

  author       = {DePond, Philip J. and Guss, Gabe and Ly, Sonny and Calta, Nicholas P. and Deane, Dave and Khairallah, Saad and Matthews, Manyalibo J.},

  abstractNote = {Here, layer-to-layer height measurements of additively manufactured 316L stainless steel using high speed spectral-domain optical coherence tomography (SD-OCT) are presented. Layers are built up using an open architecture laser powder bed fusion machine while height measurements are made in-line along the process laser path following each layer print. Printed cubes, with and without an internal ‘overhang’ channel, were built to investigate the effect of scanning parameters on surface structure. Layer-to-layer scan rotation strategy significantly impacts surface roughness between layers which in turn can influence porosity. Spatter particles, which have been correlated with numerous defect modalities, generate high points in the powder bed and can persist on a melted surface for many layers. Laser power significantly affects overhang morphology, as measured by SD-OCT. Large dross occurs in the high energy density regime, while balling and a capillary-driven coalescence of unstable melt pools perpendicular to the scanning direction occurs in the low energy density regime. High fidelity powder-scale simulations of deep powder layers were used to further elucidate the underlying physics revealed by SD-OCT measurements and high speed imaging, yielding insight to defect formation mechanisms which can lead to improved process parameters.},

  doi          = {10.1016/j.matdes.2018.05.050},

  journal      = {Materials & Design},

  number       = C,

  volume       = 154,

  place        = {United Kingdom},

  year         = {Wed May 23 00:00:00 EDT 2018},

  month        = {Wed May 23 00:00:00 EDT 2018}

}

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Works referenced in this record:

Evaluation of selective laser sintering processes by optical coherence tomography
journal, December 2015

Guan, Guangying; Hirsch, Matthias; Lu, Zeng Hai
Materials & Design, Vol. 88
DOI: 10.1016/j.matdes.2015.09.084

Process defects and in situ monitoring methods in metal powder bed fusion: a review
journal, February 2017

Grasso, Marco; Colosimo, Bianca Maria
Measurement Science and Technology, Vol. 28, Issue 4
DOI: 10.1088/1361-6501/aa5c4f

Use of track/layer morphology to develop functional parts by selective laser melting
journal, November 2013

Yadroitsev, I.; Bertrand, Ph.; Antonenkova, G.
Journal of Laser Applications, Vol. 25, Issue 5
DOI: 10.2351/1.4811838

Automatic laser welding and milling with in situ inline coherent imaging
journal, January 2014

Webster, P. J. L.; Wright, L. G.; Ji, Y.
Optics Letters, Vol. 39, Issue 21
DOI: 10.1364/OL.39.006217

A study of the microstructural evolution during selective laser melting of Ti–6Al–4V
journal, May 2010

Thijs, Lore; Verhaeghe, Frederik; Craeghs, Tom
Acta Materialia, Vol. 58, Issue 9
DOI: 10.1016/j.actamat.2010.02.004

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need
journal, April 2017

Patterson, Albert E.; Messimer, Sherri L.; Farrington, Phillip A.
Technologies, Vol. 5, Issue 2
DOI: 10.3390/technologies5020015

Design of an Optical system for the In Situ Process Monitoring of Selective Laser Melting (SLM)
journal, January 2011

Lott, Philipp; Schleifenbaum, Henrich; Meiners, Wilhelm
Physics Procedia, Vol. 12
DOI: 10.1016/j.phpro.2011.03.085

Heat treatment of Ti6Al4V produced by Selective Laser Melting: Microstructure and mechanical properties
journal, November 2012

Vrancken, Bey; Thijs, Lore; Kruth, Jean-Pierre
Journal of Alloys and Compounds, Vol. 541
DOI: 10.1016/j.jallcom.2012.07.022

Additive manufacturing of metallic components – Process, structure and properties
journal, March 2018

DebRoy, T.; Wei, H. L.; Zuback, J. S.
Progress in Materials Science, Vol. 92
DOI: 10.1016/j.pmatsci.2017.10.001

Consolidation phenomena in laser and powder-bed based layered manufacturing
journal, January 2007

Kruth, J. -P.; Levy, G.; Klocke, F.
CIRP Annals, Vol. 56, Issue 2
DOI: 10.1016/j.cirp.2007.10.004

In situ X-ray imaging of defect and molten pool dynamics in laser additive manufacturing
journal, April 2018

Leung, Chu Lun Alex; Marussi, Sebastian; Atwood, Robert C.
Nature Communications, Vol. 9, Issue 1
DOI: 10.1038/s41467-018-03734-7

Denudation of metal powder layers in laser powder bed fusion processes
journal, August 2016

Matthews, Manyalibo J.; Guss, Gabe; Khairallah, Saad A.
Acta Materialia, Vol. 114
DOI: 10.1016/j.actamat.2016.05.017

Optical sensor for real-time monitoring of CO_2 laser welding process
journal, January 2001

Ancona, Antonio; Spagnolo, Vincenzo; Lugarà, Pietro Mario
Applied Optics, Vol. 40, Issue 33
DOI: 10.1364/AO.40.006019

Fiji: an open-source platform for biological-image analysis
journal, June 2012

Schindelin, Johannes; Arganda-Carreras, Ignacio; Frise, Erwin
Nature Methods, Vol. 9, Issue 7
DOI: 10.1038/nmeth.2019

Additively manufactured hierarchical stainless steels with high strength and ductility
journal, October 2017

Wang, Y. Morris; Voisin, Thomas; McKeown, Joseph T.
Nature Materials, Vol. 17, Issue 1
DOI: 10.1038/nmat5021

Real-Time Image Processing for Monitoring of Free Weld Pool Surface
journal, May 1997

Kovacevic, R.; Zhang, Y. M.
Journal of Manufacturing Science and Engineering, Vol. 119, Issue 2
DOI: 10.1115/1.2831091

Trace-analytical methods for monitoring contaminations in semiconductor-grade Si manufacturing
journal, January 1994

Fabry, L.; Pahlke, S.; Kotz, L.
Fresenius' Journal of Analytical Chemistry, Vol. 349, Issue 4
DOI: 10.1007/BF00323201

Fundamentals of Selective Laser Melting of alloyed steel powders
journal, January 2006

Rombouts, M.; Kruth, J. P.; Froyen, L.
CIRP Annals, Vol. 55, Issue 1
DOI: 10.1016/S0007-8506(07)60395-3

Detection of Process Failures in Layerwise Laser Melting with Optical Process Monitoring
journal, January 2012

Craeghs, Tom; Clijsters, Stijn; Kruth, Jean. -Pierre
Physics Procedia, Vol. 39
DOI: 10.1016/j.phpro.2012.10.097

Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones
journal, April 2016

Khairallah, Saad A.; Anderson, Andrew T.; Rubenchik, Alexander
Acta Materialia, Vol. 108
DOI: 10.1016/j.actamat.2016.02.014

Automatic real-time guidance of laser machining with inline coherent imaging
journal, May 2011

Webster, Paul J. L.; Wright, Logan G.; Mortimer, Kevin D.
Journal of Laser Applications, Vol. 23, Issue 2
DOI: 10.2351/1.3567955

Real-time depth monitoring and control of laser machining through scanning beam delivery system
journal, March 2015

Ji, Yang; Grindal, Alexander W.; Webster, Paul J. L.
Journal of Physics D: Applied Physics, Vol. 48, Issue 15
DOI: 10.1088/0022-3727/48/15/155301

Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing
journal, June 2017

Ly, Sonny; Rubenchik, Alexander M.; Khairallah, Saad A.
Scientific Reports, Vol. 7, Issue 1
DOI: 10.1038/s41598-017-04237-z

Implementation of a thermomechanical model for the simulation of selective laser melting
journal, April 2014

Hodge, N. E.; Ferencz, R. M.; Solberg, J. M.
Computational Mechanics, Vol. 54, Issue 1
DOI: 10.1007/s00466-014-1024-2

Low Coherence Interferometry in Selective Laser Melting
journal, January 2014

Neef, A.; Seyda, V.; Herzog, D.
Physics Procedia, Vol. 56
DOI: 10.1016/j.phpro.2014.08.100

In situ 24 kHz coherent imaging of morphology change in laser percussion drilling
journal, January 2010

Webster, Paul J. L.; Yu, Joe X. Z.; Leung, Ben Y. C.
Optics Letters, Vol. 35, Issue 5
DOI: 10.1364/OL.35.000646

Optimization of Scan Strategies in Selective Laser Melting of Aluminum Parts With Downfacing Areas
journal, October 2014

Mertens, Raya; Clijsters, Stijn; Kempen, Karolien
Journal of Manufacturing Science and Engineering, Vol. 136, Issue 6
DOI: 10.1115/1.4028620

In situ morphology-based defect detection of selective laser melting through inline coherent imaging
journal, May 2016

Kanko, Jordan A.; Sibley, Allison P.; Fraser, James M.
Journal of Materials Processing Technology, Vol. 231
DOI: 10.1016/j.jmatprotec.2015.12.024

NIH Image to ImageJ: 25 years of image analysis
journal, June 2012

Schneider, Caroline A.; Rasband, Wayne S.; Eliceiri, Kevin W.
Nature Methods, Vol. 9, Issue 7
DOI: 10.1038/nmeth.2089

Modeling the interaction of laser radiation with powder bed at selective laser melting
journal, January 2010

Gusarov, A. V.; Smurov, I.
Physics Procedia, Vol. 5
DOI: 10.1016/j.phpro.2010.08.065

Real-time and in situ monitoring of mechanochemical milling reactions
journal, December 2012

Friščić, Tomislav; Halasz, Ivan; Beldon, Patrick J.
Nature Chemistry, Vol. 5, Issue 1
DOI: 10.1038/nchem.1505

Review of in-situ process monitoring and in-situ metrology for metal additive manufacturing
journal, April 2016

Everton, Sarah K.; Hirsch, Matthias; Stravroulakis, Petros
Materials & Design, Vol. 95
DOI: 10.1016/j.matdes.2016.01.099

In situ quality control of the selective laser melting process using a high-speed, real-time melt pool monitoring system
journal, August 2014

Clijsters, S.; Craeghs, T.; Buls, S.
The International Journal of Advanced Manufacturing Technology, Vol. 75, Issue 5-8
DOI: 10.1007/s00170-014-6214-8

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Title: In situ measurements of layer roughness during laser powder bed fusion additive manufacturing using low coherence scanning interferometry

Abstract

Citation Formats

Evaluation of selective laser sintering processes by optical coherence tomography journal, December 2015

Process defects and in situ monitoring methods in metal powder bed fusion: a review journal, February 2017

Use of track/layer morphology to develop functional parts by selective laser melting journal, November 2013

Automatic laser welding and milling with in situ inline coherent imaging journal, January 2014

A study of the microstructural evolution during selective laser melting of Ti–6Al–4V journal, May 2010

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need journal, April 2017

Design of an Optical system for the In Situ Process Monitoring of Selective Laser Melting (SLM) journal, January 2011

Heat treatment of Ti6Al4V produced by Selective Laser Melting: Microstructure and mechanical properties journal, November 2012

Additive manufacturing of metallic components – Process, structure and properties journal, March 2018

Consolidation phenomena in laser and powder-bed based layered manufacturing journal, January 2007

In situ X-ray imaging of defect and molten pool dynamics in laser additive manufacturing journal, April 2018

Denudation of metal powder layers in laser powder bed fusion processes journal, August 2016

Optical sensor for real-time monitoring of CO_2 laser welding process journal, January 2001

Fiji: an open-source platform for biological-image analysis journal, June 2012

Additively manufactured hierarchical stainless steels with high strength and ductility journal, October 2017

Real-Time Image Processing for Monitoring of Free Weld Pool Surface journal, May 1997

Trace-analytical methods for monitoring contaminations in semiconductor-grade Si manufacturing journal, January 1994

Fundamentals of Selective Laser Melting of alloyed steel powders journal, January 2006

Detection of Process Failures in Layerwise Laser Melting with Optical Process Monitoring journal, January 2012

Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones journal, April 2016

Automatic real-time guidance of laser machining with inline coherent imaging journal, May 2011

Real-time depth monitoring and control of laser machining through scanning beam delivery system journal, March 2015

Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing journal, June 2017

Implementation of a thermomechanical model for the simulation of selective laser melting journal, April 2014

Low Coherence Interferometry in Selective Laser Melting journal, January 2014

In situ 24 kHz coherent imaging of morphology change in laser percussion drilling journal, January 2010

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In situ morphology-based defect detection of selective laser melting through inline coherent imaging journal, May 2016

NIH Image to ImageJ: 25 years of image analysis journal, June 2012

Modeling the interaction of laser radiation with powder bed at selective laser melting journal, January 2010

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Review of in-situ process monitoring and in-situ metrology for metal additive manufacturing journal, April 2016

In situ quality control of the selective laser melting process using a high-speed, real-time melt pool monitoring system journal, August 2014

Evaluation of selective laser sintering processes by optical coherence tomography
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Process defects and in situ monitoring methods in metal powder bed fusion: a review
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Use of track/layer morphology to develop functional parts by selective laser melting
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journal, January 2014

A study of the microstructural evolution during selective laser melting of Ti–6Al–4V
journal, May 2010

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need
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Design of an Optical system for the In Situ Process Monitoring of Selective Laser Melting (SLM)
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Heat treatment of Ti6Al4V produced by Selective Laser Melting: Microstructure and mechanical properties
journal, November 2012

Additive manufacturing of metallic components – Process, structure and properties
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journal, January 2007

In situ X-ray imaging of defect and molten pool dynamics in laser additive manufacturing
journal, April 2018

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Fiji: an open-source platform for biological-image analysis
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journal, January 2006

Detection of Process Failures in Layerwise Laser Melting with Optical Process Monitoring
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Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones
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journal, January 2010

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journal, May 2016

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