Laser energy absorption behavior of powder particles using ray tracing method during selective laser melting additive manufacturing of aluminum alloy

In this paper, a three-dimensional powder bed model, considering Fresnel absorption of S and P polarization and multiple reflections, has been reasonably proposed. The coupled interaction of the powder bed particles and laser beam energy, mainly focusing on the laser absorptivity and irradiance distribution on powder particles surface and the influence of particle size distribution on the single track molten pool, during selective laser melting additive manufacturing of AlSi12 material using the ray-tracing calculation have been thoroughly evaluated. The results indicated that the energy absorbed on the powder bed was significantly larger than that on the dense flat material and, the distribution of the irradiance was gradually decreasing from the center to the edge of the interaction region. Meanwhile, the powder bed absorptivity and the irradiance of central powder particle of powder bed were found to be sensitive to the powder particle sizes. The absorptivity of the AlSi12 powder bed decreased from 0.222 to 0.123 for the particle size ranging from 10 mu m to 60 mu m, respectively. The contour of the irradiance distribution continuously changed from the uniform pattern to the double peak and terminally to the single peak for the increase in the particle size. The influence of the particle size on the cross section of the single-track morphology was experimentally studied, having a good agreement with the results predicted by the simulation. (c) 2018 Elsevier Ltd. All rights reserved.