Selective laser melting of an oxide dispersion strengthened (ODS) γ-TiAl alloy towards production of complex structures

Publication date: 15 November 2017
Source:Materials & Design, Volume 134
Author(s): C. Kenel, G. Dasargyri, T. Bauer, A. Colella, A.B. Spierings, C. Leinenbach, K. Wegener
The selective laser melting of oxide dispersion strengthened Ti-45Al-3Nb-Y2O3 with a focus on processing parameters and layer-wise re-scanning strategies is described. Smooth melt pools are observed in single line deposition for laser powers of 100 to 200W at low scanning speeds. Increased porosity is observed at energies exceeding 150W. Laser melting scans on sintered material show a common behavior of melt pool width and depth as a function of radiant exposure at 100 to 200W. Deep welding and keyhole formation is observed at 150W to 200W exceeding a radiant exposure of 20J/mm². Re-scanning strategies in multi-layer deposits are found to reduce cracking frequency significantly. Re-scans with a 90° orientation are superior to scans with 0° and 45° with respect to the initial deposition scan and reduce the cracking frequency by a factor of 2 without preheating. In free-standing lattice structures re-scanning was found to be mostly detrimental which is explained by their low heat transport towards the base plate. The results clearly demonstrate the potential of re-scanning strategies in manufacturing of structural intermetallics at ambient temperatures, which are usually processed at high preheating temperatures.

Graphical abstract

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