Microstructure and Elevated Temperature Flexure Testing of Tungsten Produced by Electron Beam Additive Manufacturing

Due to their superior high-temperature thermomechanical capabilities and excellent resistance to
hydrogen isotopes, tungsten materials have garnered significant interest in fusion nuclear applications.
However, the high hardness and low ductility at room temperature present significant challenges for
traditional fabrication. The electron beam additive manufacturing has shown promise in manufacturing
pure tungsten via high kinetic energy input, elevated surface temperature, and tightly controlled
vacuum environment. This talk explores the material process, structure, and property relationship of
pure tungsten produced by electron beam powder bed fusion (EB-PBF). The 99.8% relative density of
pure tungsten with reduced cracking was achieved by purposely isolating the build substrate and
optimizing the parameter suite. The equiaxed microstructure along the build direction, which is
distinctive from the normal columnar texture, was obtained and could be attributed to the minimized
cooling rate. Subgrains were presented in all inspected regions, with misorientation along the grain
boundary and cracks, possibly due to the deformation-induced recrystallization from high thermal
strain. A comparatively easy-setup flexural testing will be introduced to investigate the material tensile
response at the ambient and elevated temperature over the ductile-to-brittle transition threshold, for
electron beam additively manufactured tungsten bars.