Effect of Laser Power and Powder Flow Rate on Properties of Laser Metal Deposited Ti6Al4V

Laser Metal Deposition (LMD) is an additive manufacturing process with capabilities that include: producing new part directly from 3 Dimensional Computer Aided Design (3D CAD) model, building new part on the existing old component and repairing an existing high valued component parts that would have been discarded in the past. With all these capabilities and its advantages over other additive manufacturing techniques, the underlying physics of the LMD process is yet to be fully understood probably because of high interaction between the processing parameters and studying many parameters at the same time makes it further complex to understand. In this study, the effect of laser power and powder flow rate on physical properties (deposition height and deposition width), metallurgical property (microstructure) and mechanical (microhardness) properties on laser deposited most widely used aerospace alloy are studied. Also, because the Ti6Al4V is very expensive, and LMD is capable of reducing buy-to-fly ratio of aerospace parts, the material utilization efficiency is also studied. Four sets of experiments were performed and repeated to establish repeatability using laser power of 1.8 kW and 3.0 kW, powder flow rate of 2.88 g/min and 5.67 g/min, and keeping the gas flow rate and scanning speed constant at 2 l/min and 0.005 m/s respectively. The deposition height / width are found to increase with increase in laser power and increase in powder flow rate. The material utilization is favoured by higher power while higher powder flow rate reduces material utilization. The results are presented and fully discussed.

Authors:

• Mukul Shukla
• Rasheedat M. Mahamood
• Esther T. Akinlabi
• Sisa. Pityana

Keywords:

• Laser Metal Deposition
• Material Efficiency
• Microstructure
• Ti6Al4V.

References:

[1] E. Toyserkani, and A. Khajepour, A mechatronics approach to laser
powder deposition process. Mechatronics, (2006), vol. 16(10), pp. 631-641.
[2] D. Krantz, S. Nasla, J. Byrne, B. Rosenberger, On-demand spares
fabrication during space missions using laser direct metal deposition,
Space Technology and Applications International Forum - 200, AIP
Conference Proceedings, (2001), vol. 552, pp. 170-175.
[3] S.Y. Gao, Y.Z. Zhang, L.K. Shi, B.L. Du, M.Z. Xi, H.Z. Ji, Research on
laser direct deposition process of Ti-6Al-4V alloy. Acta Metallurgica
Sinica (English Letters), (2007), vol. 20, pp. 171-180.
[4] Y. Hu, C. Chen, K. Mukherjee, Innovative laser-aided manufacturing of
patterned stamping and cutting dies: Processing parameters. Materials
and Manufacturing Processes, (1998), vol.13 (3), pp. 369-387.
[5] X. Wu, J. Liang, J. Mei, C. Mitchell, P.S. Goodwin, W. Voice, Microstructures of laser-deposited Ti-6Al-4V, Materials & Design,
vol. 25(2), (2004), pp. 137-144.
[6] S. Bontha, The Effect of Process Variables on Microstructure in Laser-
Deposited Materials, PhD thesis, Wright State University, Engineering,
2006.
[7] T. A. Davis, The Effect of Process Parameters on Laser Deposited Ti-
6Al-4V, M.Eng thesis, University of Louisville, 2003.
[8] S. H. Mok, G. Bi, J. Folkes, I. Pashby, Deposition of Ti-6Al-4V using a
high power diode laser and wire, Part I: Investigation on the process
characteristics, Surface and Coatings Technology, vol. 202(16), (2008),
pp. 3933-3939.
[9] E. Brandl, A. Schoberth and C. Leyens, Morphology, microstructure,
and hardness of titanium (Ti-6Al-4V) blocks deposited by wire-feed
additive layer manufacturing (ALM), Materials Science and Engineering
A, vol. 532, (2012), pp. 295- 307.
[10] M. Esmailian, M. Mehrvar, Investigation of the effect of AL2O3 powder
in Electro Discharge Machining for Titanium alloys, ICME, vol. 9, (2007), pp. 549-557.
[11] R. Filip, Alloying of surface layer of the Ti-6Al-4V titanium alloy
through the laser treatment, Journal of Achievements in Materials and
Manufacturing Engineering, vol. 15(1-2), (2006), pp. 174-180.
[12] Z. M Wang, E. O. Ezugwu, Titanium Alloys and Their Machinability a
Review. Journal of Materials Processing Technology, (1997), pp. 68:262
[13] G. Kehl, Principles of Metallographic Laboratory Practice, 3rd ed.,
McGraw-Hill Book Publishing Company, New York, 1949
[14] R. M. Mahamood, E. T. Akinlabi, M. Shukla and S. Pityana, Effect of
Laser Power on Material Efficiency, Layer Height and Width of Laser
Metal Deposited Ti6Al4V, Lecture Notes in Engineering and Computer
Science: Proceedings of the World Congress on Engineering and
Computer Science, WCECS 2012, Accepted.