A study on surface morphology and tension in laser powder bed fusion of Ti-6Al-4V

Mahyar Khorasani*, Amir Hossein Ghasemi, Umar Shafique Awan, Elahe Hadavi, Martin Leary, Milan Brandt, Guy Littlefair, William O’Neil, Ian Gibson

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

When reporting surface quality, the roughest surface is a reference for the measurements. In LPBF due to recoil pressure and scan movement, asymmetric surface is shaped, and surface roughness has different values in different measurement orientations. In this research, the influence of the laser powder bed fusion (LPBF) process parameters on surface tension and roughness of Ti-6AI-4 V parts in three orientations are investigated. To improve the mechanical properties, heat treatment was carried out and added to the designed matrix to generate a comprehensive data set. Taguchi design of experiment was employed to print 25 samples with five process parameters and post-processing. The effect and interaction of the parameters on the formation of surface profile comprising tension, morphology and roughness in various directions have been analysed. The main contribution of this paper is developing a model to approximate the melting pool temperature and surface tension based on the process parameters. Other contributions are an analysis of process parameters to determine the formation and variation of surface tension and roughness and explain the governing mechanisms through rheological phenomena. Results showed that the main driving factors in the variation of surface tension and formation of the surface profile are thermophysical properties of the feedstock, rheology and the temperature of the melting pool. Also, the results showed that while the value of surface tension is the same for each test case, morphology and the value of roughness are different when analysing the surface in perpendicular, parallel and angled directions to laser movement.

Original languageEnglish
Pages (from-to)2891-2909
Number of pages19
JournalInternational journal of advanced manufacturing technology
Volume111
Issue number9-10
Early online date4 Nov 2020
DOIs
Publication statusPublished - Dec 2020

Keywords

  • UT-Hybrid-D
  • Porosity
  • Selective laser melting
  • Surface morphology
  • Surface roughness
  • Additive manufacturing

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