Emissivity Prediction for an IR Camera During Laser Welding of Aluminum

Year 2022, , 24 - 34, 01.12.2022

Antonio Metallo

https://doi.org/10.5541/ijot.1129559

Cited By: 4

Abstract

Laser processing is becoming increasingly important in industrial applications. The success of the process relies on two fundamental parameters: the surface temperature of the medium and the thickness of the hardened layer. One of the most important factors during a laser process is certainly the temperature, which presents high temperature gradients. The speed at which a material undergoes a phase transition, the chemical reactions that take place during processing and the properties of the material are all dependent on temperature changes. Consequently, the measure of temperature is a demanding undertaking. This study proposes to measure temperature for the duration of laser welding with the infrared camera (IR) Optris PI. To restore the real temperature based on the brightness temperature values measured by the IR camera is needed to evaluate the emissivity to be attributed to the IR camera. For this purpose, firstly, the isotherms consistent with the melting point of aluminum (785 K) were assessed and then compared with the temperature distribution gauged in the zone of irradiation of the laser. Such data were then compared with the thickness of the melted zone. The use of the melting point isotherm allowed the calculation of the value of emissivity and the restoration of the temperature. Thermography software data acquisition wrongly presupposes the emissivity value does not change. This generates incorrect thermographic data. The surface emissivity normally hinges on temperature. Therefore, the values on which the literature relies may not work for materials of interest in the conditions of the process. This is particularly the case, where welding is carried out in keyhole mode (Tmax = Tvap). However, the physical phenomena involved, including evaporation and plasma plume formation, high spatial and temporal temperature gradients, and non-equilibrium phase transformations, influence the optical conditions of the brightness of the emission of light from the molten pool, making, De Facto, the emissivity value not constant. Thus, what we propose here is a methodological procedure that allows the measurement of the effective emissivity of the surface, at the same time taking into consideration the consequence of physical phenomena and the conditions of the surface. Two procedures (Standard and Simplified) capable of providing the correct emissivity value in relation to the working parameters have been proposed. The results showed that the procedures are correct, fast, and easy to use.

Keywords

laser welding, emissivity, thermography, IR camera calibration

Supporting Institution

University of Salerno

References

• A. Mosavia, F. Salehib, L. Nadaie, S. Karolyc, N. E. Gorjid, “Modeling the temperature distribution during laser hardening process”, Results in Physics Volume 16, March 2020, 102883. https://doi.org/10.1016/j.rinp.2019.102883.
• H.G. Woo, H. S. Cho, “Three-dimensional temperature distribution in laser surface hardening processes”, Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture 213(7):695-712. DOI:10.1243/0954405991517128.
• I. Smurv and M. Doubenskaia, “Temperature Monitoring by Optical Methods in Laser Processing”, Chapter 9 in the Book ‘‘Laser-Assisted Fabrication of Materials’’. Springer Series in Materials Science, Vol 161, J. Dutta Majumdar and I. Manna, Ed., Springer, Berlin, 2013, p 373-422. DOI:10.1007/978-3-642-28359-8_9.
• M. Doubenskaia, M. Pavlov, S. Grigoriev, I. Smurov, “Definition of brightness temperature and restoration of true temperature in laser cladding using infrared camera”, April 2013, Surface and Coatings Technology 220:244-247. DOI: 10.1016/j.surfcoat.2012.10.044.
• M. Doubenskaia, I. Zhirnov, V. Teleshevskiy, Ph. Bertrand, I. Smurov, “Determination of True Temperature in Selective Laser Melting of Metal Powder Using Infrared Camera” November 2015 Materials Science Forum 834:93-102. DOI:10.4028/ www.scientific.net/MSF.834.93.
• Z. Lanc, B. Strbac, M. Zeljkovic, A Zivkovic, M Hadzistevic, “Emissivity of aluminium alloy using infrared thermography technique”, June 2018, Materials and Technologies 52(3). DOI:10.17222/mit.2017.152.
• A. P Tadamalle, “Review of Real-Time Temperature Measurement for Process Monitoring of Laser Conduction Welding”, Eng. Sci. Technol. An Int. J. 2(5), 946–950 (2012).
• S. M. Thompson, L. Bian, N. Shamsaei, A. Yadollahi, “An overview of Direct Laser Deposition for additive manufacturing, Part I: Transport phenomena, modeling and diagnostics”, Addit. Manuf. 8, 36–62, Elsevier B.V. (2015). https://doi.org/10.1016/j.addma.2015.07.001.
• T. Staudt, E. Eschner, M. Schmidt, “Temperature determination in laser welding based upon a hyperspectral imaging technique”, CIRP Annals Volume 68, Issue 1, 2019, Pages 225-228. https://doi.org/10.1016/j.cirp.2019.04.117.
• M. Miccio, R. Pierri, G. Cuccurullo, A. Metallo, P. Brachi, “Process intensification of tomato residues drying by microwave heating: experiments and simulation”, August 2020 Chemical Engineering and Processing 156:108082. DOI: 10.1016/j.cep.2020.108082.
• I. Mudawar, “Emissivity characteristics of roughened aluminum alloy surfaces and assessment of multispectral radiation thermometry (MRT) emissivity models”, International Journal of Heat and Mass Transfer · August 2004. DOI: 10.1016/j.ijheatmasstransfer.2004.04.025.
• I. Mudawar, “Experimental Investigation of Emissivity of Aluminum Alloys and Temperature Determination Using Multispectral Radiation Thermometry (MRT) Algorithms”, Journal of Materials Engineering and Performance · January 2002. DOI: 10.1361/105994902770343818.
• Z. Lanc, B. Strbac, M. Zeljkovic, A. Zivkovic, M. Hadzistevic, “Emissivity of aluminium alloy using infrared thermography technique”, June 2018 Materials and Technologies. doi:10.17222/mit.2017.152.
• C. Bonacina, G. Comini, A. Fassano, M. Primicerio, “Numerical solutions of phase change problems”, International Journal of Heat Mass Transfer, 16, 1825-1832 (1973)].
• C. J. Knight, “Theoretical modeling of rapid surface vaporization with back pressure”, American Institute of Aeronautics and Astronautics Journal, 17:5, 19–523 (1979).
• M. Edstorp, “Weld Pool Simulations”, in Department of Mathematical Sciences (2008), Chalmers University of Technology and University of Gothenburg. ISSN 1652-9715
• R. Fabbro, K. Chouf," “Dynamical description of the keyhole in deep penetration laser welding”, Journal of Laser Applications,12:4,142-148- (2000). https://doi.org/10.2351/1.521924.
• K. Narender, A. Sowbhagya M. Rao, K. Gopal K. Rao, N. Gopi Krishna, “Temperature Dependence of Density and Thermal Expansion of Wrought Aluminum Alloys 7041, 7075 and 7095 by Gamma Ray Attenuation Method”, Journal of Modern Physics 4(03):331-336; January 2013 DOI:10.4236/jmp.2013.43045.
• M. Leitner, T. Leitner, A. Schmon, K. Aziz, G. Pottlacher, “Thermophysical Properties of Liquid Aluminum (2017)”, Metallurgical and Materials Transactions A volume 48, pages3036–304. DOI: 10.1007/s11661-017-4053-6
• R. Paschotta, Encyclopedia of Laser Physics and Technology, “Wiley-VCH: Berlin, Germany, Vch Pub; 2° edition (22 October 2008)”. ISBN-10: 9783527408283.
• K. Suresh Kumar, T. Sparks, F. Liou, “Parameter determination and experimental validation of a wire feed Additive Manufacturing model”, In Proceedings of the 29th Annual International Solid Freeform Fabrication Symposium; An Additive Manufacturing Conference, Austin, TX,USA,pg.13–15;August-2015;URI. https://hdl.handle.net/2152/89407.
• I. Bunaziv, Odd M. Akselsen, X. Ren, B. Nyhus and M. Eriksson, “Laser Beam and Laser-Arc Hybrid Welding of Aluminium Alloys”, Metals 2021, 11(8), 1150. https://doi.org/10.3390/met11081150.
• J. Heigel, P. Michaleris, E. Reutzel, “Thermo-mechanical model development and validation of directed energy deposition additive manufacturing of Ti-6Al-4V”, Additive Manufacturing Volume 5, January 2015. Pages 9-19. https://doi.org/10.1016/j.addma.2014.10.003.
• I. Smurov, M. Doubenskaia, “Laser-Assisted Fabrication of Materials”, in Majumdar J. D. and Manna I. (eds.), (Springer Series in Materials Science 161, Springer-Verlag Berlin Heidelberg, 2013, pp. 373-422.) DOI:10.1007/978-3-642-28359-8.
• E. Filep, D. N. Kutasi, L. Kenéz, “Method for Emissivity Estimation of Metals”, Acta Materialia Transylvanica, 1/1, 2018 pg. 31-36. https://doi.org/10.2478/amt-2018-0010.