Impact of Notches on Additively Manufactured Inconel 718 Tensile Performance
Abstract
:1. Introduction
2. Materials and Methods
3. Results
3.1. Stress vs. Strain Curves
3.2. Finite Element Analysis
3.3. Notch Sensitivity
3.4. Stress vs. Strain Approximations
3.5. Fractography
4. Conclusions
- The tested L-PBF Inconel 718 material has isotropic room-temperature tensile-material performance. No significant difference was noted in the tensile data when comparing the vertical and horizontal build directions;
- The NSR for the notched specimens was independent of the notch root radii and Kt. It was determined that the average NSR of the notched specimens was 1.48. Since the NSR was found to be greater than one, it was determined that the L-PBF Inconel 718 material exhibited notch strengthening;
- The smooth specimens exhibited much higher levels of elongation due to the increase in the area for dislocations to occur and stack up, while the notched specimens only had a short length for dislocations to occur, and thus had a minimum amount of elongation prior to failure;
- The notched specimens exhibited a much higher ultimate tensile strength when compared to the smooth specimens. The cause of the increased ultimate tensile strength is expected to be similar to the reasonings reported within [15]. The increase in the ultimate tensile strength of the notched specimens is suspected to be associated with the higher level of triaxial stress near the notch tip. The triaxial stress near the notch tip produces a localized area of plastic deformation that is constrained by the bulk material. Due to this added constraint, higher stresses are required to produce failure.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
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Element | Composition (wt. %) |
---|---|
Aluminum | 0.53 |
Boron | 0.002 |
Calcium | <0.005 |
Carbon | 0.034 |
Chromium | 18.4 |
Cobalt | 0.023 |
Copper | 0.032 |
Iron | 18.05 |
Molybdenum | 2.84 |
Nickel | 54.0 |
Niobium | 4.94 |
Nitrogen | 0.0098 |
Oxygen | 0.020 |
Silicon | 0.040 |
Sulfur | 0.002 |
Titanium | 0.98 |
Specimen Type | Specimen Build Orientation | Test Quantity (Axial Strain) | Test Quantity (Diametral Strain) |
---|---|---|---|
Smooth | Vertical Horizontal | 3 3 | 2 2 |
ρ = 0.048 mm | Vertical Horizontal | 3 3 | 2 2 |
ρ = 0.597 mm | Vertical Horizontal | 3 3 | 2 2 |
ρ = 1.146 mm | Vertical Horizontal | 3 3 | 2 2 |
Orientation | Vertical | Horizontal | Vertical | Horizontal | Vertical | Horizontal |
---|---|---|---|---|---|---|
Notch Root Radius, ρ (mm) | 0.048 | 0.048 | 0.597 | 0.597 | 1.146 | 1.146 |
Kt | 12.50 | 12.50 | 4.26 | 4.26 | 3.35 | 3.35 |
Rm(N), (MPa) | 1970 | 1985 | 2082 | 2082 | 2021 | 2007 |
NSR | 1.44 | 1.45 | 1.52 | 1.52 | 1.48 | 1.46 |
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Johnson, J.; Kujawski, D. Impact of Notches on Additively Manufactured Inconel 718 Tensile Performance. Materials 2023, 16, 6740. https://doi.org/10.3390/ma16206740
Johnson J, Kujawski D. Impact of Notches on Additively Manufactured Inconel 718 Tensile Performance. Materials. 2023; 16(20):6740. https://doi.org/10.3390/ma16206740
Chicago/Turabian StyleJohnson, Joseph, and Daniel Kujawski. 2023. "Impact of Notches on Additively Manufactured Inconel 718 Tensile Performance" Materials 16, no. 20: 6740. https://doi.org/10.3390/ma16206740