Dynamic Deformation, Adiabatic Sheared Microstructures and Fractured Surfaces of an Electron Bean Additive Manufactured Ti6Al4V

Uniaxial tension and compression experiments were performed, at deformation rates covering the monotonic (10 -3 )and dynamic (2000 s -1 ) range, on Electron Beam Additive Manufactured (EBAM) Ti6Al4V specimens to elucidate their plastic flow response, deformation mechanisms and associated fracture morphology. Stress state asymmetry is explained in terms of activated slip systems while their plastic flow strain rate sensitivity is quantified by their hardening and softening rates. In contrast, ductile fracture behavior was observed irrespective of the imposed loading rate. While statically fracture tensile samples displayed a cup-and- cone topography with constant size equiaxed dimples a shear-dominated fracture, with elongated voids, was observed on the high strain rate tensile specimens. A similar microscopic analysis reveals that the dynamic compressive fracture results from the initiation and propagation of Adiabatic Shear Bands (ABS). Microstructural aspects of the sheared region were also investigated.