Fully coupled thermomechanical simulation of laser-assisted machining Ti6Al4V reveals the mechanism of morphological evolution during serrated chip formation

Laser-assisted machining (LAM) has demonstrated exceptional performance in terms of improving the machinability of difficult-to-cut materials like Ti6Al4V. This study reveals a comprehensive mechanism of the morphological evolution of serrated chips in LAM of Ti6Al4V through a fully coupled thermomechanical simulation. The laser power density is experimentally determined and implemented as a user-subroutine to reflect its real-time distribution. The validity of the model is confirmed through comparison with different modelling approaches and experimental data. On this basis, the analysis of thermomechanical deformation in the primary shear zone of the workpiece reveals that the chip morphology is caused by the thermoplastic instability due to thermal softening from laser heating. Another significant factor that contributes to the variation of chip serration is the alteration of the cutting depth, which results from thermal expansion caused by laser heating.