- freely available
Metals 2019, 9(7), 806; https://doi.org/10.3390/met9070806
1. Introduction and Literature Review
2. Experimental Setup
3. Finite Element Models
4. Results and Discussions
- Plane strain formulation was considered, i.e., lateral distortions can’t be predicted.
- Due to unavailability of data, mechanical properties of solid and powder alloys were considered the same.
- Simulation of a complete part was not considered due to the requirement of huge computational time. So, deformations present in the base part prior to the deposition of the top 20 layers was ignored.
- From the above analysis, it can be concluded that 2D FE models based on plane strain formulations are useful in predicting the overhang deformations for EBM built parts.
- The FE models underestimate the deformations in all cases and the errors are around 22%. However, the models are able to predict the effects of different support structures on overhang warping up to a reasonable degree of accuracy.
- The temperature predictions during each layer build-up could be useful in determining the phase transformation from powder to liquid and liquid to solid alloy.
- These FE models are also useful in determining the size and duration of the melt pool during each layer build-up.
- Residual stress patterns for the deposited layers are found to be very much different from the un-supported model and the overhang areas show fluctuating stresses from tensile to compressive.
- The deposited layers for the models with support structures show uniform tensile stresses, which are balanced by the compressive stresses inside the support columns.
Conflicts of Interest
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|Beam current, I (mA)||15|
|Scan speed, vs (mm/s)||4530|
|Line offset (mm)||0.1|
|Acceleration voltage, V (kV)||60|
|Electron beam diameter, d (µm)||200|
|Powder layer thickness (mm)||0.05|
|Beam penetration depth, D (mm)||1.5 layer|
|Solidus temperature (K)||1878|
|Liquidus temperature (K)||1928|
|Preheat temperature, Tinitial (K)||1003|
|Temperature Range (°C)||Thermal Conductivity (W/m.K)||Specific Heat (J/Kg-k)||Density (Kg/m3)||Yield Stress (MPa)||Young′s Modulus (GPa)||Expansion Coefficient (10–6/C°)|
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