Ultrafast Laser Asynchronous Processing for Laser Metal Deposition Manufacturing of Ti6Al4V

Additive manufacturing technology has rapidly developed to enable the manufacturing of various complex feature parts. However, parts manufactured through Laser Metal Deposition (LMD) often exhibit poor surface quality with the waviness of significant peak-to-valley distances, making it hard to improve surface quality through laser polishing. This study proposes a surface treatment method using ultrafast laser asynchronous processing to solve the issue of large waviness in Ti6Al4V parts manufactured by LMD, in which rough processing is carried out using picosecond laser with a galvanometer and precision processing is conducted using femtosecond laser with an objective lens. The influence of laser energy, defocus distance, and repetition times on material surface quality is investigated. Using the proper processing parameters, the initial surface with a step of 250 µm can be eliminated, which demonstrates the feasibility of ultrafast laser asynchronous processing in reducing peak-to-valley distance in materials.