Speaker
Description
Laser Powder Bed Fusion (LPBF) of Ti-6Al-4V produces a characteristic non-equilibrium microstructure dominated by acicular α′ martensite due to high cooling rates inherent to the process. Recent studies have demonstrated the effect of build orientation on the thermal expansion of the as-printed Ti-6Al-4V. The observed expansion was partitioned into an isotropic reversible thermal strain and an anisotropic irreversible transformation strain. The latter is associated to the crystallographic texture evolving during the solidification to β phase and subsequent β → α′ phase transformation. However, the underlying mechanisms at the microscopic scale as well as the influence of heating rate during the post processing remain insufficiently characterized.
In this study, in-situ synchrotron X-ray diffraction experiments were performed on LPBF-fabricated Ti-6Al-4V specimens to investigate the phase transformation behavior and the lattice parameter evolution during heating with rates of 10 Ks-1, 100 Ks-1 and 500 Ks-1 up to 1200°C.
Therefore, vertically and horizontally built specimens were analyzed to assess the influence of the build orientation.
The experimental results indicate that the evolution of the lattice parameters and the phase transformation kinetics are independent of the applied heating rates. Furthermore, the phase transformation kinetics and lattice evolution for both printing directions show similar behavior. Finally, the phase transformation mechanisms during heating and cooling are discussed.
| Speaker Country | Switzerland |
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| Would you like to publish your paper in the special issue of BHM "Berg- und Hüttenmännische Monatshefte" | Yes |