Influence of processing conditions on geometrical features of laser claddings obtained by powder injection
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The influence of processing conditions on the geometrical aspects of laser claddings is studied. Attention is drawn to the following laser-processing parameters: laser-power interaction time, surface of the irradiated zone, powder-feed rate. Different Ni-Cr-Co-Fe base powders are deposited on an austenitic stainless steel. It is observed that the mass of powder participating in the clad layer — which is proportional to the effective cross-sectionS of the layer — increases linearly with irradiance and interaction time. However, threshold values are detected; they are due to the existence of a minimum energy value required to melt the powder particles. The influence of the powder-feed rate, F, is more complicated. For low values,S is directly proportional toF, while beyond a critical value,F*, the powder injected in the laser beam acts as a screen, the opacity of which increases due to the multiple scattering phenomenon; energy absorption is more and more efficient and process efficiency is enhanced. However, this increase is limited to a maximum value, since the energy delivered by the laser source is also limited and since cladding requires melting of the particles. A simple explanation is proposed, based on mass- and energy-transfer governing equations.
KeywordsProcessing Condition Energy Absorption Powder Particle Austenitic Stainless Steel Interaction Time
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