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Proceedings Paper

Thermoelectric assessment of laser peening induced effects on a metallic biomaterial Ti6Al4V
Author(s): H. Carreón; S. Barriuso; J. A. Porro; J. L. González-Carrasco; J. L. Ocaña
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Paper Abstract

Laser peening has recently emerged as a useful technique to overcome detrimental effects associated to another wellknown surface modification processes such as shot peening or grit blasting used in the biomedical field. It is worth to notice that besides the primary residual stress effect, thermally induced effects might also cause subtle surface and subsurface microstructural changes that might influence corrosion resistance. Moreover, since maximum loads use to occur at the surface, they could also play a critical role in the fatigue strength. In this work, plates of Ti-6Al-4V alloy of 7 mm in thickness were modified by laser peening without using a sacrificial outer layer. Irradiation by a Q-switched Nd-YAG laser (9.4 ns pulse length) working in fundamental harmonic at 2.8 J/pulse and with water as confining medium was used. Laser pulses with a 1.5 mm diameter at an equivalent overlapping density (EOD) of 5000 cm-2 were applied. Attempts to analyze the global induced effects after laser peening were addressed by using the contacting and non-contacting thermoelectric power (TEP) techniques. It was demonstrated that the thermoelectric method is entirely insensitive to surface topography while it is uniquely sensitive to subtle variations in thermoelectric properties, which are associated with the different material effects induced by different surface modification treatments. These results indicate that the stress-dependence of the thermoelectric power in metals produces sufficient contrast to detect and quantitatively characterize regions under compressive residual stress based on their thermoelectric power contrast with respect to the surrounding intact material. However, further research is needed to better separate residual stress effects from secondary material effects, especially in the case of low-conductivity engineering materials like titanium alloys.

Paper Details

Date Published: 7 March 2014
PDF: 7 pages
Proc. SPIE 8972, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XIV, 89721Q (7 March 2014); doi: 10.1117/12.2045335
Show Author Affiliations
H. Carreón, Univ. Michoacana de San Nicolás de Hidalgo (Mexico)
S. Barriuso, Ctr. Nacional de Investigaciones Metalúrgicas (Spain)
J. A. Porro, Univ. Politécnica de Madrid (Spain)
J. L. González-Carrasco, Ctr. Nacional de Investigaciones Metalúrgicas (Spain)
Ctr. Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (Spain)
J. L. Ocaña, Univ. Politécnica de Madrid (Spain)

Published in SPIE Proceedings Vol. 8972:
Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XIV
Alexander Heisterkamp; Peter R. Herman; Michel Meunier; Stefan Nolte, Editor(s)

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