Abstract
The use of the Laser Metal Deposition (LMD) technology as a manufacturing and repairing technique in industrial sectors like the die and mold and aerospace is increasing within the last decades. Research carried out in the field of LMD process situates argon as the most usual inert gas, followed by nitrogen. Some leading companies have started to use helium and argon as carrier and shielding gas, respectively. There is therefore a pressing need to know how the use of different gases may affect the LMD process due there being a lack of knowledge with regard to gas mixtures. The aim of the present work is to evaluate the influence of a mixture of argon and helium on the LMD process by analyzing single tracks of deposited material. For this purpose, special attention is paid to the melt pool temperature, as well as to the characterization of the deposited clads. The increment of helium concentration in the gases of the LMD processes based on argon will have three effects. The first one is a slight reduction of the height of the clads. Second, an increase of the temperature of the melt pool. Last, smaller wet angles are obtained for higher helium concentrations.
Highlights
IntroductionLaser Metal Deposition (LMD) is an Additive Manufacturing (AM) technology that consists on the deposition of material layers that are melted by a laser source
The increment of helium concentration in the gases of the Laser Metal Deposition (LMD) processes based on argon will have three effects
Laser Metal Deposition (LMD) is an Additive Manufacturing (AM) technology that consists on the deposition of material layers that are melted by a laser source
Summary
Laser Metal Deposition (LMD) is an Additive Manufacturing (AM) technology that consists on the deposition of material layers that are melted by a laser source. The filler material to be deposited is usually supplied in the form of powder and is conducted through a nozzle into the melt pool, which has been created on a substrate surface by a laser beam. In this process, the powder is melted and deposited by creating a new layer of material. The entire process is carried out employing two different gas flows: a shielding gas, whose function is the generation of a protective atmosphere so that oxidation reactions are avoided, and a carrier gas that is used to transport the powder through the entire circuit and nozzle to the melt pool. It represents the largest gas flow used and it has a direct impact on the quality of the deposited material, mainly in the porosity generation, but this phenomenon can be avoided by parameters modification [3,4]
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