Abstract
A multi-scale, multi-physics modelling framework of selective
laser melting (SLM) in the nickel-based superalloy IN718 is
presented. Representative powder-bed particle distribution is
simulated using the measured size distribution from experiment.
Thermal fluid dynamics calculations are then used to predict
melting behaviour, sub-surface morphology, and porosity
development during a single pass scanning of the SLM process.
The results suggest that the pores and uneven surface structure are
exacerbated by increasing powder layer thicknesses. Predicted
porosity volume fraction is up to 12% of the single track when 5
statistical powder distributions are simulated for each powder
layer thickness. Processing-induced microstructure is predicted by
linking cellular automatons – finite element calculations indicate
further that the cooling rate is about 4400 oC/s and grain growth
strongly follows the thermal gradient giving rise to a columnar
grain morphology if homogeneous nucleation is assumed.
Random texture is likely for as-fabricated SLM single pass with
approximately 8 um and 6 um grain size for 20 um and 100 um
powder layer thickness fabrication. Use has been made of the
cooling history to predict more detailed microstructure using a γ"
precipitation model. With the short time scale of solidification and
rapid cooling, it becomes less likely that γ" precipitation will be
observed in the condition investigated unless a prolonged hold at
temperature is carried out. Future work on extension of the
proposed multiscale modelling approach on microstructure
predictions in SLM to mechanical properties will be discussed.
laser melting (SLM) in the nickel-based superalloy IN718 is
presented. Representative powder-bed particle distribution is
simulated using the measured size distribution from experiment.
Thermal fluid dynamics calculations are then used to predict
melting behaviour, sub-surface morphology, and porosity
development during a single pass scanning of the SLM process.
The results suggest that the pores and uneven surface structure are
exacerbated by increasing powder layer thicknesses. Predicted
porosity volume fraction is up to 12% of the single track when 5
statistical powder distributions are simulated for each powder
layer thickness. Processing-induced microstructure is predicted by
linking cellular automatons – finite element calculations indicate
further that the cooling rate is about 4400 oC/s and grain growth
strongly follows the thermal gradient giving rise to a columnar
grain morphology if homogeneous nucleation is assumed.
Random texture is likely for as-fabricated SLM single pass with
approximately 8 um and 6 um grain size for 20 um and 100 um
powder layer thickness fabrication. Use has been made of the
cooling history to predict more detailed microstructure using a γ"
precipitation model. With the short time scale of solidification and
rapid cooling, it becomes less likely that γ" precipitation will be
observed in the condition investigated unless a prolonged hold at
temperature is carried out. Future work on extension of the
proposed multiscale modelling approach on microstructure
predictions in SLM to mechanical properties will be discussed.
| Original language | English |
|---|---|
| Title of host publication | Superalloys 2016 |
| Subtitle of host publication | Proceedings of the 13th International Symposium on Superalloys |
| Editors | Mark Hardy |
| Publisher | John Wiley & Sons |
| Pages | 1021-1030 |
| Number of pages | 10 |
| ISBN (Print) | 978-1-118-99666-9 |
| Publication status | Published - Nov 2016 |
| Event | 13th International Symposium on Superalloys, SUPERALLOYS 2016 - Seven Springs, United States Duration: 11 Sept 2016 → 15 Sept 2016 |
Conference
| Conference | 13th International Symposium on Superalloys, SUPERALLOYS 2016 |
|---|---|
| Country/Territory | United States |
| City | Seven Springs |
| Period | 11/09/16 → 15/09/16 |