Abstract:
Dislocations play a central role in determining strength and flow properties of metals
and alloys. Di usionless phase transformation of ! in Ti6Al4V during the Direct Metal Laser
Sintering (DMLS) process produces martensitic microstructures with high dislocation densities.
However, heat treatment, such as stress relieving and annealing, can be applied to reduce the volume
of these dislocations. In the present study, an analysis of the X-ray di raction (XRD) profiles of
the non-heat-treated and heat-treated microstructures of DMLS Ti6Al4V(ELI) was carried out to
determine the level of defects in these microstructures. The modified Williamson–Hall and modified
Warren–Averbach methods of analysis were used to evaluate the dislocation densities in these
microstructures. The results obtained showed a 73% reduction of dislocation density in DMLS
Ti6Al4V(ELI) upon stress relieving heat treatment. The density of dislocations further declined in
microstructures that were annealed at elevated temperatures, with the microstructures that were
heat-treated just below the ! recording the lowest dislocation densities.
