Abstract
A process window is developed for fabricating thin walled Inconel 718 (IN718) structures for Laser Additive
Manufacturing using Directed Energy Deposition (LAM-DED). In-house developed LAM-DED setup deployed to
investigate the effect of process parameters on geometry and quality. The influence of post-heat treatment on
microstructure, surface and mechanical properties is also studied. Full factorial experiments are carried out to
derive the process window yielding requisite geometry, deposition rate and quality. The optimized process
parameters are deployed for thin wall fabrication. The maximum and minimum limits for laser energy per unit
length (E) and powder feed rate per unit length (F) are experimentally found to be 210 kJ/m, 105 kJ/m, 12.5 g/
m and 4 g/m, respectively for fabricating thin walls of requisite geometry. The fabricated thin walls are observed
to be defect free with dendritic microstructure. The microstructural examination of heat-treated samples reveals
recrystallized equiaxed grains with reduction in surface tensile residual stress up to 50%, and modified surface
topography. The reduction of average hardness by 12%, significant improvement in ductility by 62.5% and
improvement in energy storage capacity by 2.4 times are observed during the study
Manufacturing using Directed Energy Deposition (LAM-DED). In-house developed LAM-DED setup deployed to
investigate the effect of process parameters on geometry and quality. The influence of post-heat treatment on
microstructure, surface and mechanical properties is also studied. Full factorial experiments are carried out to
derive the process window yielding requisite geometry, deposition rate and quality. The optimized process
parameters are deployed for thin wall fabrication. The maximum and minimum limits for laser energy per unit
length (E) and powder feed rate per unit length (F) are experimentally found to be 210 kJ/m, 105 kJ/m, 12.5 g/
m and 4 g/m, respectively for fabricating thin walls of requisite geometry. The fabricated thin walls are observed
to be defect free with dendritic microstructure. The microstructural examination of heat-treated samples reveals
recrystallized equiaxed grains with reduction in surface tensile residual stress up to 50%, and modified surface
topography. The reduction of average hardness by 12%, significant improvement in ductility by 62.5% and
improvement in energy storage capacity by 2.4 times are observed during the study
| Original language | English |
|---|---|
| Pages (from-to) | 270-278 |
| Journal | Vacuum |
| Volume | 166 |
| DOIs | |
| Publication status | Published - 18 May 2019 |