Emissivity calibration method for pyrometer measurement of melting pool temperature in selective laser melting of stainless steel 316L

  • Chi-Guang Ren
  • Yu-Lung LoEmail author
  • Hong-Chuong Tran
  • Min-Hsun Lee


Selective laser melting (SLM) is an additive manufacturing (AM) technique for producing arbitrary work pieces, in which a laser beam is controlled to melt specific regions of a metal powder bed layer by layer so as to build up the required geometric form. In the present study, a method is proposed for calibrating the measurements obtained by a pyrometer for the melting pool temperature in the SLM of stainless steel 316L powder using the estimated values of the emissivity coefficients obtained from finite element heat transfer simulation and experimental tests. The accuracy in temperature prediction by heat transfer simulation is also confirmed by embedding a thermocouple into the powder bed. As a result, the calibration process is applicable to both one-color and two-color pyrometry methods. It is shown that the average error between the temperature measurements obtained from the calibrated pyrometer and the simulated temperature is just 1%. In other words, the feasibility of the proposed emissivity-based calibration method is confirmed. In the author’s knowledge, this is the first proposed idea to calibrate the emissivity of the pyrometer based upon the simulation model for accurately extracting the true melting pool temperature.


Emissivity Pyrometer Melting pool Selective laser melting 


Funding information

This study was financially supported by the Ministry of Science and Technology of Taiwan under Grant No. MOST 107-2218-E-006-051. The research was also partially supported by the National Chung-Shan Institute of Science and Technology under an Aerospace-Grade Large-Scale Additive Manufacture Development and Verification Project.


  1. 1.
    Gibson I, Rosen DW, Stucker B (2014) Additive manufacturing technologies. vol 17. Springer, New YorkGoogle Scholar
  2. 2.
    Kamath C, El-dasher B, Gallegos GF, King WE, Sisto A (2014) Density of additively-manufactured, 316L SS parts using laser powder-bed fusion at powers up to 400 W. Int J Adv Manuf Technol 74(1–4):65–78CrossRefGoogle Scholar
  3. 3.
    Cheng B, Lydon J, Cooper K, Cole V, Northrop P, Chou K (2018) Infrared thermal imaging for melt pool analysis in SLM: a feasibility investigation. Virtual Phys Prototyping 13(1):8–13CrossRefGoogle Scholar
  4. 4.
    Cheng B, Lydon J, Cooper K, Cole V, Northrop P, Chou K (2018) Melt pool sensing and size analysis in laser powder-bed metal additive manufacturing. J Manuf Process 32:744–753CrossRefGoogle Scholar
  5. 5.
    Criales LE, Arısoy YM, Lane B, Moylan S, Donmez A, Özel T (2017) Laser powder bed fusion of nickel alloy 625: experimental investigations of effects of process parameters on melt pool size and shape with spatter analysis. Int J Mach Tools Manuf 121:22–36CrossRefGoogle Scholar
  6. 6.
    Smurov I (2001) Pyrometry applications in laser machining. Laser-Assisted Microtechnology 2000. vol 4157. International Society for Optics and PhotonicsGoogle Scholar
  7. 7.
    Doumanidis C, Kwak Y-M (2001) Geometry modeling and control by infrared and laser sensing in thermal manufacturing with material deposition. J Manuf Sci Eng 123(1):45–52CrossRefGoogle Scholar
  8. 8.
    Smurov I, and Ignatiev M (1996) Real time pyrometry in laser surface treatment. Laser Processing: Surface Treatment and Film Deposition. Springer, Dordrecht 529–564Google Scholar
  9. 9.
    Bayle F, Doubenskaia M (2008) Selective laser melting process monitoring with high speed infra-red camera and pyrometer. Fundamentals of laser assisted micro-and nanotechnologies. vol. 6985. International Society for Optics and PhotonicsGoogle Scholar
  10. 10.
    Doubenskaia M, Pavlov M, Chivel Y (2010) Optical system for on-line monitoring and temperature control in selective laser melting technology. Key Eng Mater 437:458–461. CrossRefGoogle Scholar
  11. 11.
    Islam M, Purtonen T, Piili H, Salminen A, Nyrhilä O (2013) Temperature profile and imaging analysis of laser additive manufacturing of stainless steel. Phys Procedia 41(Supplement C):835–842. CrossRefGoogle Scholar
  12. 12.
    Chivel Y, Smurov I (2010) On-line temperature monitoring in selective laser sintering/melting. Phys Procedia 5(Part B):515–521. CrossRefGoogle Scholar
  13. 13.
    Pavlov M, Doubenskaia M, Smurov I (2010) Pyrometric analysis of thermal processes in SLM technology. Phys Procedia 5:523–531. CrossRefGoogle Scholar
  14. 14.
    Chivel Y (2013) Optical in-process temperature monitoring of selective laser melting. Phys Procedia 41(supplement C):904–910. CrossRefGoogle Scholar
  15. 15.
    Furumoto T, Ueda T, Alkahari MR, Hosokawa A (2013) Investigation of laser consolidation process for metal powder by two-color pyrometer and high-speed video camera. Cirp Ann-Manuf Techn 62(1):223–226. CrossRefGoogle Scholar
  16. 16.
    Renken V, Lübbert L, Blom H, von Freyberg A, Fischer A (2018) Model assisted closed-loop control strategy for selective laser melting. Procedia CIRP 74:659–663CrossRefGoogle Scholar
  17. 17.
    Renken V, von Freyberg A, Schünemann K, Pastors F, Fischer A (2019) In-process closed-loop control for stabilising the melt pool temperature in selective laser melting. Prog Addit Manuf:1–11Google Scholar
  18. 18.
    DeWitt DP, Nutter GD (1988) Theory and practice of radiation thermometry. Wiley, New YorkCrossRefGoogle Scholar
  19. 19.
    Doubenskaia M, Grigoriev S, Zhirnov I, Smurov I (2016) Parametric analysis of SLM using comprehensive optical monitoring. Rapid Prototyp J 22(1):40–50. CrossRefGoogle Scholar
  20. 20.
    Boley C, Khairallah S, Rubenchik A (2015) Calculation of laser absorption by metal powders in additive manufacturing. Appl Opt 54(9):2477–2482CrossRefGoogle Scholar
  21. 21.
    Tran H-C, Lo Y-L (2018) Heat transfer simulations of selective laser melting process based on volumetric heat source with powder size consideration. J Mater Process Technol 255:411–425CrossRefGoogle Scholar
  22. 22.
    Roberts I, Wang C, Esterlein R, Stanford M, Mynors D (2009) A three-dimensional finite element analysis of the temperature field during laser melting of metal powders in additive layer manufacturing. Int J Mach Tools Manuf 49(12):916–923CrossRefGoogle Scholar
  23. 23.
    Yin J, Zhu H, Ke L, Hu P, He C, Zhang H, Zeng X (2016) A finite element model of thermal evolution in laser micro sintering. Int J Adv Manuf Technol 83(9–12):1847–1859CrossRefGoogle Scholar
  24. 24.
    Tran H-C, Lo Y-L, Huang M-H (2017) Analysis of scattering and absorption characteristics of metal powder layer for selective laser sintering. IEEE/ASME Trans Mechatron 22(4):1807–1817CrossRefGoogle Scholar
  25. 25.
    Cengel Ya, Ghajar AJ, and Ma. H (2015) Heat and Mass Transfer Fundamentals & Applications. McGraw-HillGoogle Scholar
  26. 26.
    Foroozmehr A, Badrossamay M, Foroozmehr E, Si G (2016) Finite element simulation of selective laser melting process considering optical penetration depth of laser in powder bed. Mater Des 89:255–263. CrossRefGoogle Scholar
  27. 27.
    Hodge N, Ferencz R, Solberg J (2014) Implementation of a thermomechanical model for the simulation of selective laser melting. Comput Mech 54(1):33–51MathSciNetCrossRefGoogle Scholar
  28. 28.
    Gusarov A, Yadroitsev I, Bertrand P, Smurov I (2009) Model of radiation and heat transfer in laser-powder interaction zone at selective laser melting. J Heat Transf 131(7):072101CrossRefGoogle Scholar
  29. 29.
    Streek A, Regenfuss P, Exner H (2013) Fundamentals of energy conversion and dissipation in powder layers during laser micro sintering. Phys Procedia 41:858–869CrossRefGoogle Scholar
  30. 30.
    Wang X, Laoui T, Bonse J, Kruth J-P, Lauwers B, Froyen L (2002) Direct selective laser sintering of hard metal powders: experimental study and simulation. Int J Adv Manuf Technol 19(5):351–357CrossRefGoogle Scholar
  31. 31.
    King WE, Barth HD, Castillo VM, Gallegos GF, Gibbs JW, Hahn DE, Kamath C, Rubenchik AM (2014) Observation of keyhole-mode laser melting in laser powder-bed fusion additive manufacturing. J Mater Process Technol 214(12):2915–2925CrossRefGoogle Scholar
  32. 32.
    Mills KC (2002) Recommended values of thermophysical properties for selected commercial alloys. Woodhead PublishingGoogle Scholar

Copyright information

© Springer-Verlag London Ltd., part of Springer Nature 2019

Authors and Affiliations

  • Chi-Guang Ren
    • 1
  • Yu-Lung Lo
    • 1
    Email author
  • Hong-Chuong Tran
    • 1
  • Min-Hsun Lee
    • 1
  1. 1.Department of Mechanical EngineeringNational Cheng Kung UniversityTainanTaiwan

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