Laser surface processing of titanium in air: Influence of scan traces overlapping

Abstract

Laser surface treatments of titanium in air have been performed through a pulsed Nd:yttrium–aluminum–garnet (λ=1.064 μm) laser. Several samples have been obtained modifying the laser scan velocity and partial overlapping of consecutive traces, in order to study the influence of these parameters on the surface morphology. Scanning electron microscopy and profilometry measurements have revealed different surface morphologies depending on the physical processes involved in the treatments. The surfaces are melted in all cases and present a different crack configuration depending on the melting regime. In addition, at low scan velocities, the presence of a laser generated plasma results in a periodic groove structure that evolve to a flat and porous surface when the distance between traces is decreased.

Microstructure and mechanical properties of surface treated cast titanium with Nd:YAG laser

“…Moreover, the presence of characteristic peaks of TiO 2 indicated that the fluence values used in this study were high enough to promote the formation of the highly oxidized phases without argon gas shielding. This result was in agreement with previous studies [7,13] which reported that this phase was only obtained with fluence higher than 280 J/cm² under normal environmental atmosphere (corresponding fluence values vary from 340 up to 430 J/cm² for 240 V -300 V in this study). Regardless of the fluence value, the oxidation degree was reduced under the argon shielding due to the low oxygen content on the top surface.…”

“…Correlation between XRD results, AES analysis and morphological changes of the top surface microstructure validates the presence of oxide phases and surface alpha case layer. Previous reports [9,13,17] studied on laser melting of pure Ti and Ti-6Al-4V alloy found that different titanium oxides were formed in the surface layers of the samples. They also showed that the remelting significantly improved the corrosion and wear resistances.…”

“…Since the voltage controls the welding energy, an increase of voltage leads to a greater welding depth [4][5][6][7][8][9][10][11][12][13][14][15]17]. Chai and Chou [18] reported that pulse duration is not a significant factor to affect the Ultimate Tensile Strength (UTS) or the Yield Strength (YS).…”

“…Laser parameters have to be optimized in order to reduce defects and to optimize microstructure [12]. Morphology of the layers created and nature of the phases formed mostly depend on the laser beam overlapping [13], the nature of surrounding gas [4,8,[10][11], and the intensity of laser beam [10,14].…”

The influence of laser power and repetition rate on oxygen and nitrogen insertion into titanium using pulsed Nd:YAG laser irradiation

“…[1][2][3][4][5][6][7]. Many studies have dealt with the influence of overlapping [8], of the nature of the surrounding gas [9], of the intensity of the laser beam on the morphology of the layers that are created [10], and on the nature of the phases that are formed [11].…”