Product Code: ICA10_407

X-Ray Analysis of Pore Formation in Direct Metal Deposition and Its Causes
Authors:
M Naveed Ahsan, Manufacturing and Management Group,The University of Manchester; Manchester Great Britain
Andrew J Pinkerton, Manufacturing and Management Group, the University of Manchester; Manchester Great Britain
Robert Bradley, Henry Moseley X-ray Imaging Facility, School of Materials, The University of Manchester; Manchester Great Britain
Presented at ICALEO 2010

Laser direct metal deposition has wide applications in the areas of rapid manufacturing, surface coating and
component repair. Defects of interlayer and intralayer porosity are often observed in laser deposited structures
and repaired components. Interlayer porosity can be controlled to some extent by adjusting processing
parameters, but there is still disagreement as to the source of intralayer porosity and whether processing
conditions, parameters or initial powder materials are the dominant causal factors.
In this work, two samples of Ti-6Al-4V powder, prepared using gas-atomization and plasma-atomization, were
analyzed using laser diffraction and micro computed tomography with the Xradia Micro XCT machine for any
initial porosity content. A 1.5 kW diode laser with a coaxial deposition head was then used to deposit a number
of thin-wall structures with the different powders at different processing parameters. The deposited structures
were characterized using scanning electron microscopy (SEM) and optical microscopy. The results show the
effects of the processing conditions and initial powder characteristics on intralayer porosity and final deposit
properties.
Keywords: laser metal deposition, metal powder, micro computed tomography, porosity