Features of the Ti-6Al-4V microstructure and phase composition formation by changing the thermal cycle during the process of direct energy deposition

Laser and additive manufacturing technologies are revolutionizing the industrial landscape. These techniques offer unparalleled precision, efficiency, and flexibility for creating complex components. The integration of these technologies allows for rapid prototyping and the production of custom parts in small batches. Of particular interest to industry is the 3D printing of Ti-6Al-4V titanium alloys because of their unique properties. We have studied the phase transformation pathway during interlayer temperature change when different strategy deposition. Samples manufactured by direct laser deposition were analyzed using electron microscopy, X-ray diffraction and dilatometry. We demonstrate that a significant β-phase fraction variation occurs with interlayer temperature change. We reveal that the increase of interlayer temperature enhances the static and dynamic properties of deposited Ti-6Al-4V alloy due to the modification of phase composition. Interlayer temperature may be adjusted with various deposition strategies. The abrupt cyclic nature of the additive manufacturing process is what has facilitated this unusual transformation sequence. The work provides a complete and general description of the phase transformation pathway, informed by these observations. The implication of the phase transformation on mechanical properties is discussed in relation to interlayer temperature.