Influence of process parameters on penetration depth and secondary phase distribution in laser cladding of Inconel 625 alloy: A combined numerical-experimental study

This work presents a systematic numerical and experimental investigation of the laser-based directed energy deposition for the Inconel 625 superalloy, with the aim of understanding the effect of key process parameters on penetration depth and primary dendrite arm spacing (PDAS). Using the volume of fluid approach, a 3D transient thermal-fluid model was constructed to capture heat transfer, melt-pool behavior, and solidification effects. A Box–Behnken design within response surface methodology was employed, varying laser power, scanning speed, and powder feeding rate. PDAS measured from SEM images was compared with model predictions using the temperature gradient (G) and solidification rate (R) from simulations. The findings indicate that scanning speed exerts the greatest influence on penetration depth. According to the main effects analysis, raising the speed from 2 to 6 mm/s decreases penetration depth by 29%, whereas increasing laser power to 400 W results in a 24% increase. Higher powder feeding rates (8–24 g/min) decrease penetration depth by 12.5% because part of the laser energy is consumed in melting the additional powder. PDAS shows an inverse relationship with cooling rate (G × R), decreasing from approximately 9 to 2.8 μm as the cooling rate increases from about 1.0 × 103 to 8.0 × 103 K/s. At 200 W, unmelted powder particles remain in the microstructure, while at 400 W, the Nb-rich Laves phase forms at grain boundaries. The model predicts PDAS with relative errors of 1.3%–10.7%, supporting its reliability for process optimization in laser cladding of Inconel 625.