Dynamic absorption of a powder layer

The amount of energy absorbed during laser irradiation of powder layers is extremely important in accurately representing the process in numerical simulations. Experiments were conducted using a process calorimeter to measure the bulk absorption (energy transfer efficiency) during irradiation of a mild steel substrate, pure iron powder layers, and nickel alloy powder layers with a Nd:YAG laser (λ = 1.06 mm) Irradiation of the powder layers, having different thickness, was conducted using process parameters applicable to the laser cladding process. Bulk absorption on the bare, mild steel substrate was found to be 0.48. Bulk absorption was observed to increase with powder layer thickness up to approximately 3.0 mm. The bulk absorption for pure iron powder was found to be between 0.46 and 0.68, and the bulk absorption for the nickel alloy powder was found to be between 0.54 and 0.69.