Inducing Stable alpha plus beta Microstructures during Selective Laser Melting of Ti-6Al-4V Using Intensified Intrinsic Heat Treatments

Pere Barriobero-Vila (1, 2) , Joachim Gussone (1) , Jan Haubrich (1) , Stefanie Sandloebes (3) , Julio Cesar da Silva (4) , Peter Cloetens (4) , Norbert Schell (5) , Guillermo Requena (1, 6)

1 DLR Institut für Werkstoff-Forschung / Institute of Materials Research
2 Vienna Univ Technol, Inst Mat Sci & Technol, Karlspl 13-308, A-1040 Vienna, Austria
3 Rhein Westfal TH Aachen, Dept & Chair Phys Met & Met Phys, Kopernikusstr 14, D-52074 Aachen, Germany
4 ESRF - European Synchrotron Radiation Facility
5 GKSS - Helmholtz-Zentrum Geesthacht
6 Rhein Westfal TH Aachen, Metall Struct & Mat Syst Aerosp Engn, D-52062 Aachen, Germany

Selective laser melting is a promising powder-bed-based additive manufacturing technique for titanium alloys: near net-shaped metallic components can be produced with high resource-efficiency and cost savings. For the most commercialized titanium alloy, namely Ti-6Al-4V, the complicated thermal profile of selective laser melting manufacturing (sharp cycles of steep heating and cooling rates) usually hinders manufacturing of components in a one-step process owing to the formation of brittle martensitic microstructures unsuitable for structural applications. In this work, an intensified intrinsic heat treatment is applied during selective laser melting of Ti-6Al-4V powder using a scanning strategy that combines porosity-optimized processing with a very tight hatch distance. Extensive martensite decomposition providing a uniform, fine lamellar alpha + beta microstructure is obtained along the building direction. Moreover, structural evidence of the formation of the intermetallic alpha(2)-Ti3Al phase is provided. Variations in the lattice parameter of beta serve as an indicator of the microstructural degree of stabilization. Interconnected 3D networks of beta are generated in regions highly affected by the intensified intrinsic heat treatment applied. The results obtained reflect a contribution towards simultaneous selective laser melting-manufacturing and heat treatment for fabrication of Ti-6Al-4V parts

Mots clés: additive manufacturing; element partitioning; high energy synchrotron X-ray diffraction; intrinsic heat treatment; martensite decomposition; metastable phases; phase transformations; selective laser melting; synchrotron holographic X-ray computed tomography; titanium alloys

Domaines: Physique [physics]

Pere Barriobero-Vila, Joachim Gussone, Jan Haubrich, Stefanie Sandloebes, Julio Cesar da Silva, et al.. Inducing Stable alpha plus beta Microstructures during Selective Laser Melting of Ti-6Al-4V Using Intensified Intrinsic Heat Treatments. Materials, 2017, 10 (3), 14 p. ⟨10.3390/ma10030268⟩. ⟨hal-01691875⟩