Strong coupling numerical simulation study on nanosecond pulsed laser ablation of K4002 superalloy

A complete strong coupling numerical model is proposed to investigate the nanosecond pulsed laser ablation (PLA) mechanism of aviation K4002 superalloy. In the numerical model, the incident pulsed laser energy is considered as the surface heat flux with Gaussian distribution both in time and space. Deformation mesh and mesh reconstruction technique are utilized to track the ablation-induced boundary recession. In a time-step the iterations between the solution of temperature field and the boundary recession continue until the convergence is obtained, so as to realize the complete strong coupling. More over the laser-induced heat flux has always been bonded with the recession boundary, and the temperature-dependent material properties are also taken into account. The experimental research is carried out to validate the accuracy of the model, experimental and simulation results show good agreement in terms of ablation depth. Base on the model the PLA mechanism of K4002 superalloy is studied, the evolution of temperature field, the ablation zone morphology, the heat affected zone, and the recast layer formation are analyzed. The strong coupling effect in laser ablation process is fully embodied in the model, and the simulation is improved effectively, which provides an effective analysis method for the ablation mechanism of pulsed laser. The proposed model is of great significance to help us understand the mechanism of pulsed laser ablation and the optimization of processing parameters for PLA fabrication