Numerical and experimental investigation of laser drilling process of Inconel 718 superalloy and optimization of it by response surface methodology

In this paper, the simulation of fiber-laser drilling process of Inconel 718 superalloy with the thickness of 1mm is investigated through the Finite Element Method. The influence of process parameters i.e. laser pulse frequency (150 to 550 Hz), laser power (200 to 500 watts), laser focal plane position (-0.5 to +0.5 mm) and the duty cycle (30 to 70%) were investigated in 5 levels and two external parameters i.e. the hole's entrance diameter and hole taper angle, were observed to be the process output responses. By performing the statistical analysis, the input and output parameters were found to have a direct relation with each other. By an increase in each of the input variables, the hole's entrance diameter and the hole taper angel increase. Verification of model was performed by experimental results. The results of the conducted simulations and statistical analyses having been used, the laser drilling process were optimized by means of the desire ability approach. Finally, residual stress simulation of this process was carried out at optimum setting. The residual stress value on the surface of sheet is maximum (0.14 MPa) and this value decreases with increasing distance from the surface of the sample.