Study on the thermal effects of femtosecond laser ablation on Ti-6A1–4V

In order to have a deeper understanding of femtosecond (fs) laser ablation mechanism and its thermal effects on material, comparative experiments of a millisecond laser with high average power and a femtosecond laser with high peak energy were carried out on Ti-6Al-4V. The elemental composition of ablated material and the surrounding region was detected and observed by Oxford INCA energy dispersive x-ray spectroscopy (EDS) and its electronic digital imaging system respectively. The experimental results indicate that the recast layer that is typically produced in millisecond laser ablation and characterized by microcracks, bubbles, impurity, together with content increase of oxygen is not bypassed even when the material is irradiated by femtosecond laser pulses with ultrashort pulse duration and high peak energy. In contrast with the presence of recast layers in both two laser ablations, heat-affected zone (HAZ) was not found in femtosecond laser experiment although it is a representative production in millisecond laser ablation.