Microstructure and Mechanical Properties of Electron Beam Melted Ti–5Al–5Mo–5V–1Cr–1Fe Alloy

Abstract

Electron beam melting (EBM) has been prevalently employed in fabricating titanium alloys, and it is regarded as an important additive manufacturing technique that attracts significant attention. This study aims to investigate the microstructure and mechanical properties of EBM‐fabricated near β Ti‐5Al‐5Mo‐5V‐1Cr‐1Fe (Ti55511) alloy. Optical microscope (OM) and electron backscatter diffraction (EBSD) results show that the columnar prior β grains with a < 100> texture are formed on a vertical plane. Furthermore, a lamellar structure comprised of α phase (56% vol.) and retained β phase (44% vol.) is observed within the prior β grains, indicating the occurrence of a β → α transformation during the EBM process. To evaluate the anisotropy and establish the relationship between microstructures and mechanical properties, tensile and fracture toughness tests are carried out with a loading direction either parallel or perpendicular to the building direction. Tensile results exhibit high ductility (elongation > 11%) and high strength (ultimate tensile strength > 1080 MPa) in both orientations of the EBM‐fabricated specimen. The anisotropy in mechanical properties is attributed to the morphological difference between the prior β grains along the vertical and horizontal directions.