Abstract
Directed energy deposition (DED) is a metal additive manufacturing technique often used for larger-scale components and part repair. It can result in material performance that differs from conventionally processed metal. This work studies spatial and orientation-based differences in tensile properties of nickel-based alloy IN718 using in-situ x-ray computed tomography to observe internal pore populations. Anisotropy and spatial variability in mechanical properties are shown while the evolution of pore shape during deformation is measured. Measured pore deformation is compared to predict deformations simulated using a computational crystal plasticity scheme, which provides insight, through inverse modeling, to the grain orientation in which the pore resides. The measurements provide a high fidelity method to compare experimental and computational approaches to pore deformation studies. Pore deformation measurements show that pores tend to grow and elongate in the direction of loading, consistent with ductile deformation and likely deforming with the material. Generally, the pore defects observed in this material (not from lack-of-fusion) do not cause so-called premature failure, and fully developed necking occurs prior to fracture.
| Original language | English (US) |
|---|---|
| Article number | 111943 |
| Journal | International Journal of Solids and Structures |
| Volume | 256 |
| DOIs | |
| State | Published - Dec 1 2022 |
Funding
This work made use of the MatCI Facility which receives support from the MRSEC Program (National Science Foundation DMR-1720139) of the Materials Research Center at Northwestern University. We specifically thank Carla Shute at the MatCI facility for her advice during specimen preparation. Specimens were fabricated using funding from DMDII grant number 15-07-07 ; OLK, CY, and WKL thank the National Science Foundation for support under grants CMMI-1762035 and CMMI-1934367 . Part of this research was conducted while OLK held a National Research Council Postdoctoral Research Associateship at the National Institute of Standards and Technology. We gratefully acknowledge the help of J.-S. Park of APS Beamline 1ID, who provided the mini-tensile load frame used throughout the work, as well as technical support for the load frame and helpful suggestions for the research. This work made use of the MatCI Facility which receives support from the MRSEC Program (National Science Foundation DMR-1720139) of the Materials Research Center at Northwestern University. We specifically thank Carla Shute at the MatCI facility for her advice during specimen preparation. Specimens were fabricated using funding from DMDII grant number 15-07-07; OLK, CY, and WKL thank the National Science Foundation for support under grants CMMI-1762035 and CMMI-1934367. Part of this research was conducted while OLK held a National Research Council Postdoctoral Research Associateship at the National Institute of Standards and Technology. We gratefully acknowledge the help of J.-S. Park of APS Beamline 1ID, who provided the mini-tensile load frame used throughout the work, as well as technical support for the load frame and helpful suggestions for the research.
Keywords
- Additive manufacturing
- Directed energy deposition
- In-situ X-ray CT
- Mechanical property variations
- Model verification
- Pore mechanics
- Tensile testing
ASJC Scopus subject areas
- Modeling and Simulation
- General Materials Science
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Applied Mathematics
