Microstructural characteristics of titanium alloys after
laser surface modification
M.S.F. Lima1, F.Y. Sakata2, S.M. Carvalho2, A.G. Ramos3, and R. Riva1
1
Instituto de Estudos Avançados, São José dos Campos, SP, Brazil
2
Escola de Engenharia de Lorena, Universidade de São Paulo, Lorena, SP, Brazil
3
Optsensys Instrumentação Óptica e Eletrônica Ltda, São José dos Campos, SP, Brazil
Titanium alloys have been used in a number of applications in industry due to their
exceptional strength to weight ratio, relatively high melting temperature and corrosion
resistance. These alloys have been extensively used in aerospace applications as their low
density compared to steel permits weight savings. Medical engineering is also a major field of
application for titanium alloys. Unalloyed titanium and titanium alloys have been used for
years in medical engineering for a wide range of applications, some examples are: joint
replacement parts for hip, knee, shoulder, spine, elbow and wrist, dental implants and parts
for orthodontic surgery and dental prosthetics, heart pacemaker housings and artificial heart
valves, surgical instruments for heart and eye surgery, and components in high-speed blood
centrifuges. For all these applications, titanium successfully complies with the
biocompatibility and elasticity requirements. A major obstacle for wider use of titanium in
engineering parts remains on its poor wear resistance. Various surface modification
techniques have been proposed for enhancement of its friction and impact resistance [1-5]. In
the present work the laser treatment is applied to produce a wear-resistant hardened surface.
For this, three methods were employed: laser remelting, laser carburizing and laser texturing.
Laser remelting produces a rapid solidified layer of some hundred micrometers depth,
composed by primary alpha titanium dendrites with partial martensite transformation. Laser
carburizing promotes the formation of hard titanium carbide precipitates at the surface.
Finally, surface texturing involves short high intensity pulses producing shallow laser
dimples. The surface texturing induces compressive forces on the surfaces, due to the rapid
expansion and collapse of the plasma plume. The effect of each laser treatment on the
microstructural formation are presented and discussed.
Keywords: Titanium alloys, laser, laser surface treatments
Work supported by Financiadora de Estudos e Projetos - FINEP (01.05.0183.00 e
01.09.0546.00), Conselho Nacional de Pesquisas - CNPq (500240/2007-8 e 310761/2009-3)
and Fundação de Amparo à Pesquisa do Estado de São Paulo - FAPESP (2007/08265-2).
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(1991).
[4] Y.X. Lenga,, P. Yang, J.Y. Chen, H. Sun, J. Wang, G.J. Wang, N. Huang, X.B. Tian, P.K.
Chu, Surf. Coat. Technol. 138, 296 (2001).
[5] S. PalDey, S.C. Deevi, Mater. Sci. Eng. A342, 58 (2003).
Corresponding author: Milton S.F. Lima, Instituto de Estudos Avançados, C.P. 6044, CEP
12.228-970, São José dos Campos (SP), E-mail: [email protected].