Analysis of As-Built Microstructures and Recrystallization Phenomena on Inconel 625 Alloy Obtained via Laser Powder Bed Fusion (L-PBF)

Thibaut de Terris (1) , Olivier Castelnau (1) , Zehoua Hadjem-Hamouche (1) , Halim Haddadi (1) , Vincent Michel (1) , Patrice Peyre (1)

1 PIMM - Laboratoire Procédés et Ingénierie en Mécanique et Matériaux

The microstructures induced by the laser-powder bed fusion (L-PBF) process have been widely investigated over the last decade, especially on austenitic stainless steels (AISI 316L) and nickel-based superalloys (Inconel 718, Inconel 625). However, the conditions required to initiate recrystallization of L-PBF samples at high temperatures require further investigation, especially regarding the physical origins of substructures (dislocation densities) induced by the L-PBF process. Indeed, the recrystallization widely depends on the specimen substructure, and in the case of the L-PBF process, the substructure is obtained during rapid solidification. In this paper, a comparison is presented between Inconel 625 specimens obtained with different laser-powder bed fusion (L-PBF) conditions. The effects of the energy density (VED) values on as-built and heat-under microstructures are also investigated. It is first shown that L-PBF specimens created with high-energy conditions recrystallize earlier due to a larger density of geometrically necessary dislocations. Moreover, it is shown that lower energy densities offers better tensile properties for as-built specimens. However, an appropriate heat treatment makes it possible to homogenize the tensile properties.

Mots clés: laser-powder bed fusion; Inconel 625; electron backscatter diffraction (EBSD); X-ray diffraction (XRD); recrystallization; dislocation density

Domaines: Matériaux

Thibaut de Terris, Olivier Castelnau, Zehoua Hadjem-Hamouche, Halim Haddadi, Vincent Michel, et al.. Analysis of As-Built Microstructures and Recrystallization Phenomena on Inconel 625 Alloy Obtained via Laser Powder Bed Fusion (L-PBF). Metals, 2021, 11 (4), pp.619. ⟨10.3390/met11040619⟩. ⟨hal-03219499⟩