Microstructural and texture development in direct laser fabricated IN718

Abstract

Microstructural characterisation was performed for IN718 thin-walled builds, produced using direct laser fabrication (DLF), to understand the influence of the variations in the deposition path and the laser power on the microtexture, grain structures and intermetallic particle morphology development. Considerable differences were observed, with the high laser power input generating a columnar grain structure, with a strong < 001 > fibre texture along the build height, compared to a mixture of fine uniform and large columnar grains in the low power builds, with a near random texture. The influence of different DLF conditions on the formation of Laves and of δ phase was also found to be significant, with the Laves phase precipitates being larger in the high laser power sample. Carbides and δ were also present in the high power build, but were not observed in the low power samples regardless of the deposition path.