Numerical and analytical investigation on meltpool temperature of laser-based powder bed fusion of IN718

Mahyar Khorasani*, Amir Hossein Ghasemi, Martin Leary, William O'Neil, Ian Gibson, Laura Cordova, Bernard Rolfe

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Prediction of meltpool features in Laser-Based Powder Bed Fusion (LB-PBF) is a complex non-linear multiple phase dynamic problem. In this investigation, numerical simulations and analytical models are offered to predict meltpool temperature and to provide a methodology to estimate melt track quality. By determining the meltpool temperature, different rheological phenomena including recoil pressure can be controlled. Recoil pressure is known to drive the keyhole and conduction modes in LB-PBF which is an important factor to qualify the melt track. A numerical simulation was carried out using Discrete Element Method (DEM) with a range of process parameters and absorptivity ratios; allowing observation of the variation of meltpool temperature and free surface morphology, as calculated by the volume-of-fluid (VOF) method. A spatially thermophysical-based analytical model is developed to estimate meltpool temperature, based on LB-PBF process parameters and thermophysical properties of the material. These results are compared with experimentally observed meltpool depth for IN718 specimens and found to have a good accuracy. The numerical and analytic results show good agreement in the conduction mode to estimate the meltpool temperature and related phenomena such as recoil pressure to control the melt track and layering quality. The analytical model does not accurately predict the keyhole mode which may be explained by evaporation of chemical elements in the examined material.

Original languageEnglish
Article number121477
JournalInternational journal of heat and mass transfer
Volume177
Early online date8 Jun 2021
DOIs
Publication statusPublished - Oct 2021

Keywords

  • Analytical model
  • Conduction mode
  • Keyhole mode
  • Laser-based powder bed fusion
  • Meltpool temperature
  • Numerical simulation

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