Enhanced melting flow and vaporization model and its applications in pulsed laser polishing on mold steel

A developed three-dimensional finite element model to describe surface profiles and root mean square (RMS) roughness by pulsed laser polishing based on the melting flow and vaporization removal mechanism is innovatively presented. In this paper, we indicate that the melting flow and vaporization removal are the primary mechanisms in the laser polishing process and successfully simulated the S316 mold steel pulsed laser polishing via the finite element method. Notably, vaporization removal, vaporization expansion, and plasma impact pressure, which is based on the Navier-Stokes equation, continuity equation, and Marangoni effects, are crucial factors, which are creatively taken into account in this model. Besides, due to the physical parameters changing with temperature, it is critical to considering the temperature-dependent density, specific heat capacity, thermal conductivity coefficient, dynamic viscosity, and tension coefficient to make the simulation results and model accurately. In addition, the tailored model can predict the theoretical polishing surface profiles and RMS roughness based on the melting flow and vaporization removal mechanism. Regarding the single pulse laser polishing, we investigated the surface profiles and RMS roughness on different single pulse energy and pulse width. In summary, it is expected that this study could provide a theoretical reference regarding the laser polishing metals and pave the way for laser manufacturing in various industrial applications.