Effect of Scanning Strategy on Additively Manufactured Ti6Al4V

  • Nakul D. Ghate
  • Bhanupratap Gaur
  • Amber ShrivastavaEmail author
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)


This study investigates the influence of different scanning strategies on the hardness of the parts, fabricated by direct metal laser melting. In this work, pre-alloyed powder of titanium alloy (Ti–6Al–4V) is used to produce dense parts with three different scanning strategies: unidirectional, alternate, and cross-hatching. A numerical scheme is developed to predict the heat transfer, fluid flow, and thermal history-based phase transformation during the process. Surface hardness is calculated from the obtained phase fractions. Hardness is measured experimentally, and X-ray diffraction is used for phase identification. The hardness is found to be highly dependent on the microstructure of as-built parts. The results show that rapid solidification during direct metal laser melting leads to the formation of hcp-structured acicular martensite from the parent beta phase, which increases the hardness. Higher part densities are observed for cross-hatching strategy compared to other scanning strategies. The predicted maximum hardness for different scanning strategies compare well against the experimental observations.


Direct metal laser sintering Scanning strategy Phase transformation Microhardness 


  1. 1.
    Kumar S (2003) Selective laser sintering: a qualitative and objective approach. JOM 55(10):43–47CrossRefGoogle Scholar
  2. 2.
    Khaing MW, Fuh JYH, Lu L (2001) Direct metal laser sintering for rapid tooling: processing and characterization of EOS parts. J Mater Process Technol 113:269–272CrossRefGoogle Scholar
  3. 3.
    King D, Tansey T (2002) Alternative materials for rapid tooling. J Mater Process Technol 121:313–317CrossRefGoogle Scholar
  4. 4.
    Gibson I, Rosen DW, Stucker B (2010) Additive manufacturing technologies—rapid prototyping to direct digital manufacturing. Springer Science + Business Media, LLC, New York, NYGoogle Scholar
  5. 5.
    Dahotre NB, Harimkar SP (2008) Laser fabrication and machining of materials. Springer Science + Business Media, LLC, New York, NYGoogle Scholar
  6. 6.
    Mellor S, Hao L, Zhang D (2014) Additive manufacturing: a framework for implementation. Int J Prod Econ 149:194–201CrossRefGoogle Scholar
  7. 7.
    Ruffo M, Hague RJM (2007) Cost estimation for rapid manufacturing—simultaneous production of mixed components using laser sintering. Proc Inst Mech Eng, Part B: J Eng Manuf 221(11):1585–1591CrossRefGoogle Scholar
  8. 8.
    Atkinson D (1997) Rapid prototyping and tooling, a practical guide. Strategy Publication Ltd., Welwyn Garden City, UKGoogle Scholar
  9. 9.
    Hänninen J (2001) DMLS moves from rapid tooling to rapid manufacturing. Met Powder Rep 56(9):24–29CrossRefGoogle Scholar
  10. 10.
    Steen WM, Mazumder J (2010) Laser material processing, 4th edn. Springer-Verlag London Limited, London, UKCrossRefGoogle Scholar
  11. 11.
    Hopkinson N, Hague R, Dickens P (2006) Rapid manufacturing: an industrial revolution for the digital age. John Wiley & Sons, Chichester, UKGoogle Scholar
  12. 12.
    Farshidianfar MH, Khajepour A, Gerlich AP (2016) Effect of real-time cooling rate on microstructure in laser additive manufacturing. J Mater Process Technol 231:468–478CrossRefGoogle Scholar
  13. 13.
    Bidare P et al (2018) Fluid and particle dynamics in laser powder bed fusion. Acta Mater 142:107–120Google Scholar
  14. 14.
    Qiu C et al (2015) On the role of melt flow into the surface structure and porosity development during selective laser melting. Acta Mater 96:72–79Google Scholar
  15. 15.
    Murr LE et al (2009) Microstructure and mechanical behavior of Ti–6Al–4V produced by rapid-layer manufacturing, for biomedical applications. J Mech Behav Biomed Mater 2(1):20–32CrossRefGoogle Scholar
  16. 16.
    Thijs L et al (2010) A study of the microstructural evolution during selective laser melting of Ti–6Al–4V. Acta Mater 58.9:3303–3312Google Scholar
  17. 17.
    Chlebus E et al (2011) Microstructure and mechanical behaviour of Ti–6Al–7Nb alloy produced by selective laser melting. Mater Charact 62.5:488–495Google Scholar
  18. 18.
    Voller VR, Swaminathan CR (1991) ERAL Source-based method for solidification phase change. Numer Heat Transfer, Part B Fundam 19.2:175–189Google Scholar
  19. 19.
    Mills KC (2002) Recommended values of thermophysical properties for selected commercial alloys. Woodhead PublishingGoogle Scholar
  20. 20.
    Welsch G, Boyer R, Collings EW (eds) (1993) Materials properties handbook: titanium alloys. ASM internationalGoogle Scholar
  21. 21.
    Lips T, Fritsche B (2005) A comparison of commonly used re-entry analysis tools. Acta Astronaut 57(2-8):312–323CrossRefGoogle Scholar
  22. 22.
    Kelly SM (2004) Thermal and microstructure modeling of metal deposition processes with application to Ti–6Al–4V. Ph.D. thesis.
  23. 23.
    Charles C, Järvstråt N (2009) Modelling Ti–6Al–4V microstructure by evolution laws implemented as finite element subroutines: application to TIG metal deposition. In: David SA et al (eds) Proceedings of the 8th international conference on trends in welding research (TWR), Pine Mountain, Georgia (USA), pp 477–485Google Scholar
  24. 24.
    Murgau CC, Pederson R, Lindgren LE (2012) A model for Ti–6Al–4V microstructure evolution for arbitrary temperature changes. Model Simul Mater Sci Eng 20(5).
  25. 25.
    Irwin J, Reutzel ET, Michaleris P, Keist J, Nassar AR (2016) Predicting microstructure from thermal history during additive manufacturing for Ti–6Al–4V. J Manufact Sci Eng 138.
  26. 26.
    Hahn JD, Shin YC, Krane MJM (2007) Laser transformation hardening of Ti–6Al–4V in solid state with accompanying kinetic model. Surf Eng 23(2):78–82CrossRefGoogle Scholar
  27. 27.
    Hollander DA, von Walter M, Wirtz T, Sellei R, Schmidt-Rohlfing B, Paar O et al (2006) Biomater 27(7):955–963CrossRefGoogle Scholar
  28. 28.
    Rombouts M (2006) PhD thesis. KU LeuvenGoogle Scholar
  29. 29.
    Dinda GP, Dasgupta AK, Mazumder J (2009) Laser aided direct metal deposition of Inconel 625 superalloy: microstructural evolution and thermal stability. Mater Sci Eng, A 509(1-2):98–104CrossRefGoogle Scholar

Copyright information

© The Minerals, Metals & Materials Society 2020

Authors and Affiliations

  • Nakul D. Ghate
    • 1
  • Bhanupratap Gaur
    • 1
  • Amber Shrivastava
    • 1
    Email author
  1. 1.Department of Mechanical EngineeringIndian Institute of Technology BombayMumbaiIndia

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