Monday  |  Executive AB  |  04:20 PM–04:40 PM

#19800, Evolution of Precipitates and Microhardness of PBF-LB Inconel 625 Through Relevant Thermal Treatment

Laser powder bed fusion (PBF-LB) is a metal additive manufacturing technique (AM) that produces a unique microstructure significantly different than wrought microstructure. This technique is often used to produce parts of Inconel 625 (IN625) which is a Ni-based superalloy with complex microstructure. Different secondary phases are formed in this alloy under elevated temperature conditions. This study focuses on these precipitates in IN625 produced by the L-PBF technique. Heat treatments at 700℃ and 900℃ were performed to encourage precipitation of strengthening γʺ and detrimental δ phase, respectively. Separate samples were heat treated at 1050℃ as well to dissolve these precipitates. The evolution of each of these precipitates as well as carbides and metallic oxide particles were discussed separately in this study. γʺ precipitates were found in as-printed condition and at 700℃. δ precipitates were detected at 700 and 900℃. Carbides and Al-rich oxides were observed in all conditions of L-PBF IN625. Texture analysis showed grain growth along the build direction with strong (100) texture at temperatures up to 900℃. Weak and random texture with equiaxed grains were observed at 1050℃ which is similar to wrought IN625.
Keywords: Additive Manufacturing, Laser Powder Bed Fusion, Ni-based superalloy, Microstructure, δ precipitate, γʺ precipitate.

Tahmina Keya   Auburn University
Barton Prorok   Auburn University