Utilization of multi-pass laser processing strategy for enhancing the capability of low power ns laser for machining of Ti-6Al-4V alloy

The present study aims to investigate the deep machining of Ti-6Al-4V alloy using a nanosecond (ns) laser through multi-pass and gas pressure. Experiments were conducted based on Full factorial design (FFD) by varying gas pressure and laser process parameters (LPP). Results showed that deeper grooves could be achieved through multi-pass laser scanning support with appropriate gas flow rate and laser parameters. A higher gas flow rate leads to more efficient removal of material and a faster machining rate. Further, the present findings revealed the substantial influence of laser power on the depth and width of the machined features, accounting for 41.28% and 7.11% of the variations, respectively. Moreover, power exhibited a significant impact on the taper angle (20.69%) and the heat-affected zone (HAZ) (12.04%) during the machining process. Additionally, the utilization of a multi-pass laser scan demonstrated a remarkable effect on the depth (1.89%), width (3.3%), HAZ (9.96%), and taper angle (8.78%). Furthermore, the assisted gas flow rate displayed a significant influence on the machined groove profile, that is, depth (41.97%), width (67.6%), HAZ (65.48%), and taper angle (30.15%). To achieve optimized results for high-depth machining with minimal defect, the present study recommends employing an average power of 40 W, an assisted gas flow rate of 25 L/min, and conducting four passes. These parameters develop laser machined surface with a high depth (~1499 µm) while simultaneously minimizing Taper (1.87°) and narrow HAZ (83 µm). Further, these conditions are suitable for laser cutting, trepanning, and surface texturing using a low-power laser system of Ti-6Al-4V alloy.