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Chapitre D'ouvrage Année : 2013

Prediction and analytical description of single laser tracks geometry. Characterization and analysis of 316L stainless steel microstructure

Résumé

Direct Laser Fabrication (DLF) is a process making possible the manufacture of functional parts directly from a command file injecting powder in a laser beam. The powder melting and solidification processes lead to the fabrication of this part layer by layer. In this study, deposition of 316L stainless steel powder on a steel substrate is carried out using a 700W fiber laser. Three values of each processing parameters (laser power $P$, scanning speed $V$ and powder mass flow $Q_m$) are fixed and so 27 different experiments have been made and analyzed. The layer geometry is an important process characteristic and its mastery is essential to control the final part fabrication. Analytical relationships between the laser tracks geometrical characteristics (width, height, area, penetration depth) and the processing parameters are established. The proposed analytical relationships look like $y=a_0(P^{\alpha_1}Q_m^{\alpha_2}V^{\alpha_3})+b_0$ where $y$ is one of these geometrical characteristics. Two kinds of models are explored to predict the clad geometrical form and characteristics. The first one is an analytical model in which the powder distribution in the feed jet is supposed to govern the laser clad geometry. It is then proved that the powder distribution in the jet can't determinate the final clad geometry. In the second one the general form of the clad cross section is supposed to be a disk due to the surface tension forces. Analytical relationships are established between the radius and the disk centre on one hand and the process parameters on the other hand. Comparisons between experimental observations and simulated geometries are very convincing. Thermal study is carried out using the one source point method and the so called Green functions. The microstructure is experimentally observed, analyzed and explained with the thermal modelling through the solidification front velocity and the temperature gradients calculations.
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Dates et versions

hal-01007535 , version 1 (13-08-2020)

Identifiants

  • HAL Id : hal-01007535 , version 1

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Hussam El Cheikh, Bruno Courant. Prediction and analytical description of single laser tracks geometry. Characterization and analysis of 316L stainless steel microstructure. Laser Technology, Applications and Future Prospects (Lasers and Electro-Optics Research and Technology), 2013. ⟨hal-01007535⟩
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