TY - JOUR

T1 - A comparative study of laser direct metal deposition characteristics using gas and plasma-atomized Ti-6Al-4V powders

AU - Ahsan, M. Naveed

AU - Pinkerton, Andrew J.

AU - Moat, Richard J.

AU - Shackleton, Judith

PY - 2011/9/25

Y1 - 2011/9/25

N2 - 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 1.5 kW 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 alpha + beta and not martensitic. The lamellar alpha + beta phase spacing (S alpha+beta) 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 alpha + beta phase spacing (S alpha+beta) and PREP powder deposits show lower micro hardness than GA powder deposits. (C) 2011 Elsevier B.V. All rights reserved.

AB - 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 1.5 kW 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 alpha + beta and not martensitic. The lamellar alpha + beta phase spacing (S alpha+beta) 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 alpha + beta phase spacing (S alpha+beta) and PREP powder deposits show lower micro hardness than GA powder deposits. (C) 2011 Elsevier B.V. All rights reserved.

KW - Laser direct metal deposition

KW - Micro computed tomography

KW - PREP powder

KW - Microstructure

KW - Micro hardness

U2 - 10.1016/j.msea.2011.06.074

DO - 10.1016/j.msea.2011.06.074

M3 - Journal article

VL - 528

SP - 7648

EP - 7657

JO - Materials Science and Engineering: A

JF - Materials Science and Engineering: A

SN - 0921-5093

IS - 25-26

ER -