Analysis of Microhardness after Turning Process of Ti6Al4V-ELI

This study investigated the effect of cutting parameters on the microhardness of Ti6Al4V ELI during dry turning using PVD AlTiN and TiAlN inserts. Addressing the challenge of balancing productivity with stringent surface integrity requirements, this research explored the influence of cutting speed (80, 125, and 170 m/min) and feed rate (0.08, 0.15, and 0.20 mm/rev) on subsurface microhardness. Vickers microhardness testing revealed a clear work hardening tendency, with the highest microhardness observed in the subsurface region. Increasing cutting speed correlated with increased microhardness, particularly when using PVD TiAlN inserts, indicating a greater degree of microstructural alteration. A thicker white layer was observed after turning with PVD AlTiN inserts compared to PVD TiAlN, potentially due to differences in friction coefficient. Maximum microhardness (398 HV0.05) was recorded at 125 m/min cutting speed and 0.20 mm/rev feed rate with PVD TiAlN. The machining affected zone (MAZ) extended to 200 µm and 300 µm below the surface for AlTiN and TiAlN inserts, respectively. These findings provide insights for optimizing machining processes to enhance both surface integrity and productivity in the manufacturing of Ti6Al4V ELI components.