Study on surface heat-affected zone and surface quality of Ti-6Al-4V alloy by laser-assisted micro-cutting

This paper takes Ti-6Al-4V alloy as an example to carry out laser-assisted machining experiment and simulation. It mainly studies the influence of laser power and cutting speed on the heat-affected zone of the material surface. The effects of laser power, cutting speed and cutting depth on tool wear, surface quality, and residual stress on this basis were also investigated. The experimental results show that laser power (P) and cutting speed (v) are important factors affecting the width (Wd) of the heat-affected zone of the workpiece surface. The relationship can be described as follows Wd = 116.278 + 2.587 × P − 5.191 × v. The results of simulation and experiment show that Ti-6Al-4V alloy discolors when exposed to temperatures from 105 to 130 °C under laser irradiation. During the laser-assisted machining experiment, tool flank wear occurs and the main wear patterns are adhesive wear, flaking, and micro-chipping. When the laser power is 40 W, the cutting speed is 18 m/min, and the cutting depth is 10 μm, an improved roughness value of 0.271 μm can be obtained. The residual compressive stress and microhardness of the machined surface obtained by laser-assisted machining are higher as compared to the conventional machining method. Moreover, as the laser power increases, the surface residual compressive stress exhibits an increasing trend while the microhardness first increases and then decreases.