Research Papers

Predicting Microstructure Evolution During Directed Energy Deposition Additive Manufacturing of Ti-6Al-4V

[+] Author and Article Information
Cengiz Baykasoglu

Department of Mechanical Engineering,
Hitit University,
Corum 19030, Turkey
e-mail: cengizbaykasoglu@hitit.edu.tr

Oncu Akyildiz

Department of Metallurgical
and Materials Engineering,
Hitit University,
Corum 19030, Turkey
e-mail: oncuakyildiz@hitit.edu.tr

Duygu Candemir

Department of Metallurgical
and Materials Engineering,
Hitit University,
Corum 19030, Turkey
e-mail: duygukorsacilar@hitit.edu.tr

Qingcheng Yang

Department of Mechanical Engineering
and Materials Science,
University of Pittsburgh,
Pittsburgh, PA 15261
e-mail: qzy25@psu.edu

Albert C. To

Department of Mechanical Engineering
and Materials Science,
University of Pittsburgh,
Pittsburgh, PA 15261
e-mail: albertto@pitt.edu

1Corresponding authors.

2Present address: Department of Materials Science and Engineering, Penn State University, N-257 Millennium Science Complex, State College, PA 16802.

Manuscript received September 25, 2017; final manuscript received December 20, 2017; published online February 23, 2018. Assoc. Editor: Zhijian J. Pei.

J. Manuf. Sci. Eng 140(5), 051003 (Feb 23, 2018) (11 pages) Paper No: MANU-17-1600; doi: 10.1115/1.4038894 History: Received September 25, 2017; Revised December 20, 2017

Laser engineering net shaping (LENS) is one of the representative processes of directed energy deposition (DED) in which a moving heat source having high-intensity melts and fuses metal powders together to print parts. The complex and nonuniform thermal gradients during the laser heating and cooling cycles in the LENS process directly affect the microstructural characteristics, and thereby the ultimate mechanical properties of fabricated parts. Therefore, prediction of microstructure evolution during the LENS process is of paramount importance. The objective of this study is to present a thermo-microstructural model for predicting microstructure evolution during the LENS process of Ti-6Al-4V. First, a detailed transient thermal finite element (FE) model is developed and validated for a sample LENS process. Then, a density type microstructural model which enables calculation of the α-phase fractions (i.e., Widmanstätten colony and basketweave α-phase fractions), β-phase fraction, and alpha lath widths during LENS process is developed and coupled to the thermal model. The microstructural algorithm is first verified by comparing the phase fraction results with the results presented in the literature for a given thermal history data. Second, the average lath width values calculated using the model are compared with the experimentally measured counterparts, where a reasonable agreement is achieved in both cases.

Copyright © 2018 by ASME
Your Session has timed out. Please sign back in to continue.


Murr, L. E. , Gaytan, S. M. , Ramirez, D. A. , Martinez, E. , Hernandez, J. , Amato, K. N. , Shindo, P. W. , Medina, F. R. , and Wicker, R. B. , 2012, “ Metal Fabrication by Additive Manufacturing Using Laser and Electron Beam Melting Technologies,” J. Mater. Sci. Technol., 28(1), pp. 1–14. [CrossRef]
Sandia National Laboratories, 2002, “Laser Engineered Net Shaping, Manufacturing Technologies,” Sandia National Laboratories, Albuquerque, NM, accessed Sept. 15, 2017, http://www.sandia.gov/mst/pdf/LENS.pdf
Mudge, R. P. , and Wald, N. R. , 2007, “ Laser Engineered Net Shaping Advances Additive Manufacturing and Repair,” Weld. J., 86(1), pp. 44–48.
Palčič, I. , Balažic, M. , Milfelner, M. , and Buchmeister, B. , 2009, “ Potential of Laser Engineered Net Shaping (LENS) Technology,” Mater. Manuf. Processes, 24(7–8), pp. 750–753. [CrossRef]
Gu, D. D. , Meiners, W. , Wissenbach, K. , and Poprawe, R. , 2012, “ Laser Additive Manufacturing of Metallic Components: Materials, Processes and Mechanisms,” Int. Mater. Rev., 57(3), pp. 133–164. [CrossRef]
Frazier, W. E. , 2014, “ Metal Additive Manufacturing: A Review,” J. Mater. Eng. Perform., 23(6), pp. 1917–1928. [CrossRef]
Guo, N. , and Leu, M. C. , 2013, “ Additive Manufacturing: Technology, Applications and Research Needs,” Front. Mech. Eng., 8(3), pp. 215–243. [CrossRef]
Gibson, I. , Rosen, D. W. , and Stucker, B. , 2010, Additive Manufacturing Technologies, Springer, New York. [CrossRef]
Thompson, S. M. , Bian, L. , Shamsaei, N. , and Yadollahi, A. , 2015, “ An Overview of Direct Laser Deposition for Additive Manufacturing—Part I: Transport Phenomena, Modeling and Diagnostics,” Addit. Manuf., 8, pp. 36–62. [CrossRef]
Shamsaei, N. , Yadollahi, A. , Bian, L. , and Thompson, S. M. , 2015, “ An Overview of Direct Laser Deposition for Additive Manufacturing—Part II: Mechanical Behavior, Process Parameter Optimization and Control,” Addit. Manuf., 8, pp. 12–35. [CrossRef]
Wu, X. , Liang, J. , Mei, J. , Mitchell, C. , Goodwin, P. S. , and Voice, W. , 2004, “ Microstructures of Laser-Deposited Ti–6Al–4V,” Mater. Des., 25(2), pp. 137–144. [CrossRef]
Vastola, G. , Zhang, G. , Pei, Q. X. , and Zhang, Y. W. , 2016, “ Modeling the Microstructure Evolution During Additive Manufacturing of Ti6Al4V: A Comparison Between Electron Beam Melting and Selective Laser Melting,” JOM, 68(5), pp. 1370–1375. [CrossRef]
Zhai, Y. , Galarraga, H. , and Lados, D. A. , 2016, “ Microstructure, Static Properties, and Fatigue Crack Growth Mechanisms in Ti-6Al-4V Fabricated by Additive Manufacturing: LENS and EBM,” Eng. Failure Anal., 69, pp. 3–14. [CrossRef]
Bian, L. , Thompson, S. M. , and Shamsaei, N. , 2015, “ Mechanical Properties and Microstructural Features of Direct Laser-Deposited Ti-6Al-4V,” JOM, 67(3), pp. 629–638. [CrossRef]
Marshall, G. J. , Young , W. J., II , Thompson, S. M. , Shamsaei, N. , Daniewicz, S. R. , and Shao, S. , 2016, “ Understanding the Microstructure Formation of Ti-6Al-4V During Direct Laser Deposition Via in-Situ Thermal Monitoring,” JOM, 68(3), pp. 778–790. [CrossRef]
Lundbäck, A. , and Lindgren, L. E. , 2011, “ Modelling of Metal Deposition,” Finite Elem. Anal. Des., 47(10), pp. 1169–1177. [CrossRef]
Lindgren, L. E. , Lundbäck, A. , Fisk, M. , Pederson, R. , and Andersson, J. , 2016, “ Simulation of Additive Manufacturing Using Coupled Constitutive and Microstructure Models,” Addit. Manuf., 12(Part B), pp. 144–158. [CrossRef]
Goldak, J. A. , and Akhlaghi, M. , 2005, Computational Welding Mechanics, Springer Science & Business Media, New York.
Lindgren, L. E. , 2006, “ Numerical Modelling of Welding,” Comput. Methods Appl. Mech. Eng., 195(48), pp. 6710–6736. [CrossRef]
Lindgren, L. E. , 2007, Computational Welding Mechanics: Thermomechanical and Microstructural Simulations, Woodhead Publishing, Cambridge, UK. [CrossRef]
Anca, A. , Fachinotti, V. D. , Escobar‐Palafox, G. , and Cardona, A. , 2011, “ Computational Modelling of Shaped Metal Deposition,” Int. J. Numer. Methods Eng., 85(1), pp. 84–106. [CrossRef]
Costa, L. , Vilar, R. , Reti, T. , and Deus, A. M. , 2005, “ Rapid Tooling by Laser Powder Deposition: Process Simulation Using Finite Element Analysis,” Acta Mater., 53(14), pp. 3987–3999. [CrossRef]
Wang, L. , and Felicelli, S. , 2006, “ Analysis of Thermal Phenomena in LENS™ Deposition,” Mater. Sci. Eng. A, 435–436, pp. 625–631. [CrossRef]
Ye, R. , Smugeresky, J. E. , Zheng, B. , Zhou, Y. , and Lavernia, E. J. , 2006, “ Numerical Modeling of the Thermal Behavior During the LENS® Process,” Mater. Sci. Eng. A, 428(1), pp. 47–53. [CrossRef]
Peyre, P. , Aubry, P. , Fabbro, R. , Neveu, R. , and Longuet, A. , 2008, “ Analytical and Numerical Modelling of the Direct Metal Deposition Laser Process,” J. Phys. D, 41(2), pp. 1–10. [CrossRef]
Neela, V. , and De, A. , 2009, “ Three-Dimensional Heat Transfer Analysis of LENS™ Process Using Finite Element Method,” Int. J. Adv. Manuf. Technol., 45(9–10), pp. 935–943. [CrossRef]
Zhu, G. , Zhang, A. , Li, D. , Tang, Y. , Tong, Z. , and Lu, Q. , 2011, “ Numerical Simulation of Thermal Behavior During Laser Direct Metal Deposition,” Int. J. Adv. Manuf. Technol., 55(9–12), pp. 945–954. [CrossRef]
Fachinotti, V. D. , Cardona, A. , Baufeld, B. , and Van der Biest, O. , 2012, “ Finite-Element Modelling of Heat Transfer in Shaped Metal Deposition and Experimental Validation,” Acta Mater., 60(19), pp. 6621–6630. [CrossRef]
Zhang, Y. , Yu, G. , and He, X. , 2012, “ Numerical Study of Thermal History in Laser Aided Direct Metal Deposition Process,” Sci. China Phys., Mech. Astron., 55(8), pp. 1431–1438. [CrossRef]
Michaleris, P. , 2014, “ Modeling Metal Deposition in Heat Transfer Analyses of Additive Manufacturing Processes,” Finite Elem. Anal. Des., 86, pp. 51–60. [CrossRef]
Ding, J. , Colegrove, P. , Mehnen, J. , Williams, S. , Wang, F. , and Almeida, P. S. , 2014, “ A Computationally Efficient Finite Element Model of Wire and Arc Additive Manufacture,” Int. J. Adv. Manuf. Technol., 70(1–4), pp. 227–236. [CrossRef]
Heigel, J. C. , Michaleris, P. , and Reutzel, E. W. , 2015, “ Thermo-Mechanical Model Development and Validation of Directed Energy Deposition Additive Manufacturing of Ti–6Al–4V,” Addit. Manuf., 5, pp. 9–19. [CrossRef]
Yang, Q. , Zhang, P. , Cheng, L. , Min, Z. , Chyu, M. , and To, A. C. , 2016, “ Finite Element Modeling and Validation of Thermomechanical Behavior of Ti-6Al-4V in Directed Energy Deposition Additive Manufacturing,” Addit. Manuf., 12(Part B), pp. 169–177. [CrossRef]
Vastola, G. , Zhang, G. , Pei, Q. X. , and Zhang, Y. W. , 2016, “ Controlling of Residual Stress in Additive Manufacturing of Ti6Al4V by Finite Element Modeling,” Addit. Manuf., 12(Part B), pp. 213–239.
Zhang, J. , Liou, F. , Seufzer, W. , and Taminger, K. , 2016, “ A Coupled Finite Element Cellular Automaton Model to Predict Thermal History and Grain Morphology of Ti-6Al-4V During Direct Metal Deposition (DMD),” Addit. Manuf., 11, pp. 32–39. [CrossRef]
Grong, Ø. , and Shercliff, H. R. , 2002, “ Microstructural Modelling in Metals Processing,” Prog. Mater. Sci., 47(2), pp. 163–282. [CrossRef]
Froes, F. H. , and Dutta, B. , 2014, “ The Additive Manufacturing (AM) of Titanium Alloys,” Adv. Mater. Res., 1019, pp. 19–25. [CrossRef]
Kelly, S. M. , 2004, “Thermal and Microstructure Modeling of Metal Deposition Processes With Application to Ti-6Al-4V,” Ph.D. thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA.
Kelly, S. M. , and Kampe, S. L. , 2004, “ Microstructural Evolution in Laser-Deposited Multilayer Ti-6Al-4V Builds—Part I: Microstructural Characterization,” Metall. Mater. Trans. A, 35(6), pp. 1861–1867. [CrossRef]
Kelly, S. M. , and Kampe, S. L. , 2004, “ Microstructural Evolution in Laser-Deposited Multilayer Ti-6Al-4V Builds—Part II: Thermal Modeling,” Metall. Mater. Trans. A, 35(6), pp. 1869–1879. [CrossRef]
Kolmogorov, A. N. , 1937, “ On the Statistical Theory of the Crystallization of Metals,” Bull. Acad. Sci. USSR, Math. Ser., 1, pp. 355–359.
Johnson, W. A. , and Mehl, R. F. , 1939, “ Reaction Kinetics in Processes of Nucleation and Growth,” Trans. AIME, 135(8), pp. 416–458.
Avrami, M. , 1941, “ Granulation, Phase Change, and Microstructure Kinetics of Phase Change—III,” J. Chem. Phys., 9(2), pp. 177–184. [CrossRef]
Sha, W. , and Malinov, S. , 2009, Titanium Alloys: Modelling of Microstructure, Properties and Applications, Woodhead Publishing, Cambridge, UK. [CrossRef]
Scheil, E. , 1935, “ Anlaufzeit der Austenitumwandlung,” Arch. Eisenhüttenwes, 8(12), pp. 564–567.
Christian, J. W. , 2012, Theory of Phase Transformations in Metals and Alloys, Newnes, Burlington, MA.
Koistinen, D. P. , and Marburger, R. E. , 1959, “ A General Equation Prescribing the Extent of the Austenite-Martensite Transformation in Pure Iron-Carbon Alloys and Plain Carbon Steels,” Acta Metall., 7(1), pp. 59–60. [CrossRef]
Mur, F. G. , Rodriguez, D. , and Planell, J. A. , 1996, “ Influence of Tempering Temperature and Time on the α′-Ti-6Al-4V Martensite,” J. Alloys Compd., 234(2), pp. 287–289. [CrossRef]
Ahmed, T. , and Rack, H. J. , 1998, “ Phase Transformations During Cooling in α+ β Titanium Alloys,” Mater. Sci. Eng. A, 243(1), pp. 206–211. [CrossRef]
Elmer, J. W. , Palmer, T. A. , Babu, S. S. , Zhang, W. , and DebRoy, T. , 2004, “ Phase Transformation Dynamics During Welding of Ti–6Al–4V,” J. Appl. Phys., 95(12), pp. 8327–8339. [CrossRef]
Charles, C. , 2008, “Modelling Microstructure Evolution of Weld Deposited Ti-6Al-4V,” Master's thesis, Luleå University of Technology, Luleå, Sweden.
Charles, C. , and Järvstråt, N. , 2009, “ Modelling Ti–6Al–4V Microstructure by Evolution Laws Implemented as Finite Element Subroutines: Application to TIG Metal Deposition,” Eighth International Conference on Trends in Welding Research (TWR), Pine Mountain, GA, June 1–6, pp. 477–485.
Murgau, C. C. , Pederson, R. , and Lindgren, L. E. , 2012, “ A Model for Ti–6Al–4V Microstructure Evolution for Arbitrary Temperature Changes,” Modell. Simul. Mater. Sci. Eng., 20(5), p. 055006.
Fan, Y. , Cheng, P. , Yao, Y. L. , Yang, Z. , and Egland, K. , 2005, “ Effect of Phase Transformations on Laser Forming of Ti–6Al–4V Alloy,” J. Appl. Phys., 98(1), p. 013518.
Crespo, A. , and Vilar, R. , 2010, “ Finite Element Analysis of the Rapid Manufacturing of Ti–6Al–4V Parts by Laser Powder Deposition,” Scr. Mater., 63(1), pp. 140–143. [CrossRef]
Crespo, A. , 2011, Convection and Conduction Heat Transfer, INTECH Open Access Publisher, Rijeka, Croatia, Chap. 15.
Suárez, A. , Tobar, M. J. , Yáñez, A. , Pérez, I. , Sampedro, J. , Amigó, V. , and Candel, J. J. , 2011, “ Modeling of Phase Transformations of Ti6Al4V During Laser Metal Deposition,” Phys. Procedia, 12(Part A), pp. 666–673. [CrossRef]
Irwin, J. , Reutzel, E. T. , Michaleris, P. , Keist, J. , and Nassar, A. R. , 2016, “ Predicting Microstructure From Thermal History During Additive Manufacturing for Ti-6Al-4V,” ASME J. Manuf. Sci. Eng., 138(11), p. 111007.
Marion, G. , Cailletaud, G. , Colin, C. , and Mazière, M. , 2014, “ A Finite Element Model for the Simulation of Direct Metal Deposition,” 33rd International Congress on Applications of Lasers & Electro-Optics (ICALEO), San Diego, CA, Oct. 19–23, Paper No. 1801.
Goldak, J. , Chakravarti, A. , and Bibby, M. , 1984, “ A New Finite Element Model for Welding Heat Sources,” Metall. Trans. B, 15(2), pp. 299–305. [CrossRef]
Gil, F. , Ginebra, M. , Manero, J. , and Planell, J. , 2001, “ Formation of a-Widmanstatten Structure: Effects of Grain Size and Cooling Rate on the Widmanstatten Morphologies and on the Mechanical Properties in Ti6Al4V Alloy,” J. Alloys Compd., 329(1), pp. 142–152. [CrossRef]
Gong, X. , Lydon, J. , Cooper, K. , Chou, K. , and Branch, N. , 2013, “ Microstructural Characterization and Modeling of Beam Speed Effects on Ti-6Al-4V by Electron Beam Additive Manufacturing,” 25th International of Solid Freeform Fabrication Symposium (SFF), Austin, TX, Aug. 4–6, pp. 459–469.
Farrar, P. A. , and Margolin, H. , 1961, “ The Titanium Rich Region of the Titanium-Aluminum-Vanadium System,” Trans. AIME, 221, pp. 1214–1221.
Rasband, W. S. , 2016, “ImageJ,” U. S. National Institutes of Health, Bethesda, MD, accessed Sept. 10, 2017, https://imagej.nih.gov/ij/
Sahoo, S. , and Chou, K. , 2016, “ Phase-Field Simulation of Microstructure Evolution of Ti–6Al–4V in Electron Beam Additive Manufacturing Process,” Addit. Manuf., 9, pp. 14–24. [CrossRef]


Grahic Jump Location
Fig. 1

The overall procedure for prediction of the thermal and microstructural outputs

Grahic Jump Location
Fig. 2

Illustration of deposition process

Grahic Jump Location
Fig. 3

Double ellipsoid heat source model

Grahic Jump Location
Fig. 4

Flowchart for the microstructural model

Grahic Jump Location
Fig. 5

Time–temperature–transformation diagram for α-phases. The diagram is based on the calculations presented inRef. [38] and plotted by using the piecewise polynomials reported in Ref. [53].

Grahic Jump Location
Fig. 6

Equilibrium α-phase fraction as a function of temperature given by Eq. (8) and experimental values from Ref. [63]

Grahic Jump Location
Fig. 7

Thermocouples measurement points on the top and bottom surfaces of substrate

Grahic Jump Location
Fig. 8

Temperature history comparison between the simulation and experimental measurements at P1 and P2

Grahic Jump Location
Fig. 9

(a) The primary and secondary heat treatment curve given by Kelly [38] and ((b) and (c)) corresponding α phase fractions and computed phase fractions in the present work using the same temperature–time data

Grahic Jump Location
Fig. 10

The microstructure of the five-layer LENS deposited sample: (a)–(c) preparation of the sample, (d) optical microscopy, (e) a representative SEM micrograph showing α laths, and (f) experimental and simulated average lath widths versus layer number

Grahic Jump Location
Fig. 11

(a) Temperatures in Celsius, (b) total—α, (c) colony—α, and (d) basketweave—α phase fractions evolution during layer-by-layer deposition

Grahic Jump Location
Fig. 12

Temperature, alpha phase fractions, and lath width evolution for the points probed from successive layers, layers 1–5 in (a)–(e), starting from the base point A (at the first layer) shown in Fig. 13

Grahic Jump Location
Fig. 13

(a) Position of probed points, (b) temperature profiles for point A, (c) point B, and (d) time elapsed (Δti=tfi−tsi) during β → colony—α transformation and corresponding colony—α fraction formed




Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In