Abstract
Direct energy deposition (DED) is an efficient manufacturing process for the fabrication of complex parts and repair of worn-out turbine blades. In DED, all the injected powder is not going to melt and solidify due to spattering, reflection, ejection, effect of inert gas, and turbulence around the melt pool. In this study, through numerical simulation, the effect of powder size and inert gas flow under coaxial nozzle was analyzed. The number of particle participation in the melt pool by the effect of inert gas and the size of powder particles were analyzed. The powder particle sizes considered for the study were 50–60, 60–70, 70–80, 80–90, 90–100, and 45–90 µm. Argon and helium gases were used as carrier gas and shielding gas, respectively. According to gas–solid multiphase simulation, the convergence distance of the powder flow and powder participation focal point was analyzed through numerical simulation. The simulated results showed that using argon gas as a carrier gas produced high powder efficiency compared to helium gas. The focal point is forming at 11.86 mm, approximately 12 mm from the nozzle exit, which occurred for 60–70-µm particle size. The powder particle participation efficiency obtained was 64.1% using argon gas as carrier gas.
Highlights
Direct energy deposition (DED) is called as laser engineered net shaping, direct metal deposition, and 3D laser cladding
Focusing on the reduction of the powder supply efficiency and increasing melting efficiency, a complex interaction between the gas flow and the powder interferes with the movement of the powder. The results of this investigation indicated the importance of powder size and supply of shielding and carrier gas, which supported the earlier investigation of powder particle participation in melt pool at a focal point of laser and powder convergence
In DED, the bead is formed on the substrate supplying metal powder through a coaxial nozzle using inert (Ar, He) carrier gas and with irradiation of a laser beam simultaneously
Summary
Direct energy deposition (DED) is called as laser engineered net shaping, direct metal deposition, and 3D laser cladding. The gas-solid two-phase flow theory was used to investigate the effect of deposited layer shape on coaxial powder feeding nozzle in metal forming process as well as the effect of deposited layers on powder concentration distribution and focal point distance from nozzle exit to the convergence point (the center of the convergent zone). They demonstrated that, under unequal wall thickness of component production conditions, the additive height of the layer cladded was not uniform. The results of this investigation indicated the importance of powder size and supply of shielding and carrier gas, which supported the earlier investigation of powder particle participation in melt pool at a focal point of laser and powder convergence
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