Characterization of laser peening-induced effects on a biomedical Ti6Al4V alloy by thermoelectric means

Abstract

Laser peening has recently emerged as a useful technique to overcome detrimental effects associated with other well-known surface modification processes such as shot peening or grit blasting used in the biomedical field. It is worthwhile 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 and fatigue strength of structural components. 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 at the fundamental 1064-nm wavelength at 2.8 J/pulse and with water as a confining medium was used. Laser pulses with a 1.5-mm diameter at an equivalent overlapping density of 5000 cm−2 were applied. Attempts to analyze the global-induced effects after laser peening were addressed by using the contacting and noncontacting thermoelectric power techniques.