Build Orientation and Surface Roughness Effects on the Microstructure, Mechanical Properties, and Fatigue Behavior of Electron Beam Melted Ti-6Al-4V

Selective Electron Beam Melting (SEBM) is a novel powder-bed-fusion additive manufacturing (AM) method in which a high powdered electron beam is rapidly scanned over a powder bed to produce fully dense parts. Currently, a lack of understanding of how the process parameters and build set up affect the fatigue behavior of SEBM Ti-6Al-4V components prevent its widespread use in the aerospace industry. To address these issues, rectangular blocks were fabricated using an Arcam Q10 SEBM machine. The fatigue behavior of as-built material was investigated using 4-point bend testing. Interrupted fatigue tests to monitor in-situ crack initiation and growth were also performed. Mechanical strength of the material was characterized by measuring the tensile strength and Vickers micro-hardness. Optical microscopy and electron back scattered diffraction were used to analyze the microstructure. The tensile ductility and fatigue behavior displayed an orientation dependence but the strength of the material was similar regardless of orientation