A comparative study of laser direct metal deposition characteristics using gas and plasma-atomized Ti-6Al-4V powders

M. Naveed Ahsan, Andrew J. Pinkerton, Richard J. Moat, Judith Shackleton

Research output: Contribution to journalArticlepeer-review

Abstract

This research presents a comparative study of the characteristics of laser direct metal deposition (LDMD) using two types of Ti-6Al-4V powder. Ti-6Al-4V powders prepared using the gas-atomization (GA) and the plasma rotating electrode (PREP) processes were first analyzed using laser diffraction, scanning electron microscopy and micro computed tomography. A 1.5kW diode laser with a coaxial deposition head was then used to deposit a number of thin-wall structures at a range of processing parameters from each of the powders. The deposited structures were characterized using optical microscopy, scanning electron microscopy, X-ray diffraction and micro computed tomography (MicroCT). The results show some potential benefits of using PREP powder in laser direct metal deposition. PREP powder has a higher deposition rate and deposits show lower intralayer porosity and lower surface roughness. In both cases, deposits of Ti-6Al-4V exhibit a unique epitaxial prior beta grains microstructure that transforms to alpha lathes and retained beta during cooling. X-ray diffraction results show that the overall microstructure is α+β and not martensitic. The lamellar α+β phase spacing (Sα+β) increases with laser power but seems unaffected by variation in the mass flow rate of the powder. Micro hardness of the laser deposited Ti-6Al-4V is dependent on the lamellar α+β phase spacing (Sα+β) and PREP powder deposits show lower micro hardness than GA powder deposits. © 2011 Elsevier B.V.
Original languageEnglish
Pages (from-to)7648-7657
Number of pages9
JournalMaterials Science and Engineering A
Volume528
Issue number25-26
DOIs
Publication statusPublished - 25 Sept 2011

Keywords

  • Laser direct metal deposition
  • Micro computed tomography
  • Micro hardness
  • Microstructure
  • PREP powder

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