Texture evolution as a function of scan strategy and build height in electron beam melted Ti-6Al-4V

Area of Science:

• Materials Science
• Additive Manufacturing
• Crystallography

Background:

• Metal additive manufacturing (AM) offers design freedom but lacks control over alloy microstructures.
• Controlling grain morphology, crystallographic texture, and phase content is crucial for engineering performance.
• Existing methods for texture assessment in AM may not capture all components due to symmetry assumptions.

Purpose of the Study:

• To assess the crystallographic texture in electron beam melted (EBM) Ti-6Al-4V.
• To investigate the influence of scan strategy and build height on texture.
• To correlate crystallographic texture with microstructure and solidification theory.

Main Methods:

• Corroborative neutron diffraction and large-scale electron backscatter diffraction (EBSD) were employed.
• Crystallographic texture was evaluated using triclinic specimen symmetry for comprehensive analysis.
• Parent phase β-Ti reconstructions were used to analyze grain morphology and texture.

Main Results:

• Scan strategy significantly affects texture, while build height has minimal impact.
• Spot melt strategies yield finer grains and stronger 001_β fiber textures compared to raster strategies.
• A novel $01\overline{1}{2}_{\alpha }$ fiber texture correlates with spot melting and specific α-Ti orientations after transformation.

Conclusions:

• Triclinic symmetry is essential for accurate texture assessment in AM metals.
• Scan strategy is a critical parameter for controlling microstructure and texture in EBM Ti-6Al-4V.
• The $01\overline{1}{2}_{\alpha }$ fiber texture can serve as a diagnostic for evaluating AM build quality.