Abstract
Fractured tensile specimens of INCONEL 718 manufactured via directed energy deposition (DED) with operando thermal metrics and control were heat treated and their mechanical properties were compared as a function of the time spent in the solidification and cooling temperature ranges. Shorter solidification times (faster solidification rates) during the DED process led to higher concentrations of Nb, Al, Mo, and Ti supersaturated in the Fe-Cr-Ni matrix, leading to higher volume fractions of γ’’ strengthening phases and higher hardness after aging (720°/8 h, 620 °C/10 h). This trend persists through hot isostatic pressing (1180 °C at 150 MPa for 4 h), suggesting that secondary treatment processes are not sufficient to fully dissolve detrimental Laves and carbide phases, which initially formed during solidification and affect the alloy's hardness. However, samples with various post-solidus cooling times during the DED process exhibited equivalent hardness after aging, suggesting that the intrinsic heat treatment effect is entirely replaced by the post-processing aging treatment. This study shows that the solidification rate during DED has a lasting effect on the part's mechanical properties, that is not completely mitigated by post-processing treatments, while the initial effects of the post-solidus cooling rate (intrinsic heat treatment) disappear after secondary processes.
| Original language | English (US) |
|---|---|
| Article number | 117047 |
| Journal | Journal of Materials Processing Technology |
| Volume | 291 |
| DOIs | |
| State | Published - May 2021 |
Funding
This research received funding from the US Army Research Laboratory (award W911NF-19-2-0092 ). JAG and JB were supported by the Army Research Laboratory (ARL) Oak Ridge Associated Universities (ORAU) via a Journeyman Fellowship grant. This work made use of the EPIC facility of Northwestern University’s NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource ( NSF ECCS-1542205 ); the MRSEC program ( NSF DMR-1720139 ) at the Materials Research Center ; the International Institute for Nanotechnology (IIN) ; the Keck Foundation ; and the State of Illinois , through the IIN. This work also made use of the Center for Hierarchical Materials and Design (CHiMaD under grant No. 70NANB14H012 ) Metals Processing Facility, and the MatCI Facility which receives support from the MRSEC Program ( NSF DMR-1720139 ) of the Materials Research Center at Northwestern University. The authors acknowledge Suman Bhandari (NU) for assistance with the Bruker Alicona notch measurement and thank Prof. David Dunand (NU), Prof. Gregory Wagner (NU), and Dr. Jon-Erik Mogonye (U.S. Army Research Laboratory, Adelphi) for numerous useful discussions. This research received funding from the US Army Research Laboratory (award W911NF-19-2-0092). JAG and JB were supported by the Army Research Laboratory (ARL) Oak Ridge Associated Universities (ORAU) via a Journeyman Fellowship grant. This work made use of the EPIC facility of Northwestern University's NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. This work also made use of the Center for Hierarchical Materials and Design (CHiMaD under grant No. 70NANB14H012) Metals Processing Facility, and the MatCI Facility which receives support from the MRSEC Program (NSF DMR-1720139) of the Materials Research Center at Northwestern University. The authors acknowledge Suman Bhandari (NU) for assistance with the Bruker Alicona notch measurement and thank Prof. David Dunand (NU), Prof. Gregory Wagner (NU), and Dr. Jon-Erik Mogonye (U.S. Army Research Laboratory, Adelphi) for numerous useful discussions.
Keywords
- Directed energy deposition
- Hot isostatic pressing
- Inconel 718
- Solidification rate
- Thermal control
ASJC Scopus subject areas
- Ceramics and Composites
- Computer Science Applications
- Metals and Alloys
- Industrial and Manufacturing Engineering