On the application of the anisotropic enhanced thermal conductivity approach to thermal modelling of laser-based powder bed fusion processes

Sagar Nikam, Hao Wu, Ryan Harkin, Justin Quinn, Rocco Lupoi, Shuo Yin, Shaun McFadden

Research output: Contribution to journalArticlepeer-review

Abstract

Computational simulation of the Powder Bed Fusion (PBF) process is a useful tool for predicting and analysing melt pool geometry during the deposition process. Advanced models that use Computational Fluid Dynamics (CFD) can accurately simulate the complex melt pool dynamics of the process but are typically computationally onerous to implement. CFD models require thermophysical data over a large temperature range that may be difficult to acquire for the material systems of interest. Heat conduction models, which are useful to industrial end users are easier to implement, but their accuracy can be compromised. The main difference between heat conduction and CFD modelling is the absence of convection (especially Marangoni convection). However, several sources in literature have highlighted a simple approach to mimicking the effects of Marangoni convection on the melt pool by artificially increasing the thermal conductivity of the liquid. However, due to its simplicity and lack of agreement within literature, the modified heat conduction approach is neither sufficiently robust nor universally consistent. Comparison to experimental data is lacking. In the present work, the heat conduction model is modified using an orthotropic description of anisotropic thermal conductivity in the liquid phase by applying directional correction factors. The correction factors are calibrated by comparing the predicted geometry against experimentally-obtained melt pool dimensions for single-layer, multiple tracks in Ti-6Al-4V processed by laser-PBF. After appropriate correction factors were selected, the modified heat conduction model gave results in good agreement with experiments. To test the general applicability of the approach, data from literature were analysed and simulated using the model. After correction factors were adjusted accordingly, the simulated results were validated over the range of power levels and scan speeds.

Original languageEnglish
Article number102870
JournalAdditive Manufacturing
Volume55
Early online date4 May 2022
DOIs
Publication statusE-pub ahead of print - 4 May 2022

Bibliographical note

Funding Information:
This research (SN, HW, RH, JQ, SMF) has been supported by the INTERREGVA , Ireland (Project ID: IVA5055, Project Reference Number: 047). The North West Centre for Advanced Manufacturing (NW CAM) project is supported by the European Union's INTERREG VA Programme , managed by the Special EU Programmes Body (SEUPB). The views and opinions in this document do not necessarily reflect those of the European Commission or the Special EU Programmes Body (SEUPB). Catalyst in Northern Ireland may be contacted for further information in relation to the NW CAM project. The authors would like to acknowledge the support of Patrick Walls, Wilson McKay, and the staff at Laser Prototypes Europe for giving access to their additive manufacturing facilities.

Funding Information:
This research (SN, HW, RH, JQ, SMF) has been supported by the INTERREGVA, Ireland (Project ID: IVA5055, Project Reference Number: 047). The North West Centre for Advanced Manufacturing (NW CAM) project is supported by the European Union's INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB). The views and opinions in this document do not necessarily reflect those of the European Commission or the Special EU Programmes Body (SEUPB). Catalyst in Northern Ireland may be contacted for further information in relation to the NW CAM project. The authors would like to acknowledge the support of Patrick Walls, Wilson McKay, and the staff at Laser Prototypes Europe for giving access to their additive manufacturing facilities.

Publisher Copyright:
© 2022 Elsevier B.V.

Keywords

  • Additive manufacturing
  • Directional correction factor
  • Heat conduction model
  • Marangoni convection
  • Melt pool dimensions
  • Powder bed fusion

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