Ultrasonic-assisted wire and electron beam additive manufacturing of an Ti6Al4V alloy: structures, phase and mechanical characteristics

The microstructure of samples of Ti6Al4V alloy obtained by wire and electron beam additive manufacturing (WEBAM) is characterized by the presence of columnar prior β-Ti grain boundaries and eutectoid α / β structures with wide α-Ti laths and thin β-Ti interlayers. This type of structure is a direct consequence of relatively low cooling rates and great depth of fusion during the layer-by-layer deposition. Such a coarse-grained structure leads to the mechanical properties of WEBAM materials generally characterized by high ductility but low strength, as well as anisotropy of mechanical characteristics. The prior β-Ti grain refinement in the Ti6Al4V alloy can be achieved using ultrasonic treatment directly during the WEBAM. It has been established that ultrasonic-assisted WEBAM (UAWEBAM) conducted at a US power of 350 W interferes with the epitaxial growth of prior columnar β-Ti grains and reduces the degree of crystallographic texturing. Despite the preservation of some prior elongated β-Ti grains, their longitudinal and transverse dimensions, as well as the thickness of the α-Ti laths were significantly reduced. It has been experimentally shown that the application of ultrasound to the substrate does not allow completely eliminating the anisotropy of the mechanical properties. The strength characteristics increased on average by 50 MPa only in the zone directly adjacent to the ultrasound source, while in the upper layers of the product, they are on average 30 MPa lower than in control samples manufactured without the use of ultrasound.

1. Russian Science Foundation - grant No. 25-19-20142 (https://rscf.ru/project/25-19-20142)
2. subsidy grant allocated by the Department of Scientific, Technological Development and Innovative Activities of Tomsk Region - Agreement No. 02/3/2026