Towards high efficiency and low residual stress for parallel multi-arc directed energy deposited titanium-alloy components with uniform mechanical properties

Directed energy deposition (DED) is a viable manufacturing method for producing large-sized complex structural engineering parts, yet it suffers from inherent drawbacks of low processing efficiency and high residual stress. Here, the fabrication of a long-wall titanium-alloy part was pioneered using a self-developed parallel multi-arc DED technique. The deposition efficiency is as high as 1.34 kg h⁻¹, which is approximately four times that of the well-established single DED (0.336 kg h⁻¹). As revealed by experimental testing and finite element analysis, multi-arc DED significantly reduces the distortion (from 74.9 to 55.2 mm) and the residual stress (from 82.1 to 39.6 MPa for the long-wall part), compared with those of the single-arc DED counterpart. Crack formation is effectively suppressed via argon atmosphere during the DED manufacturing process, which is associated with improved ductility. The mechanical properties of the multi-arc DED part are position-independent and consistent, and similar to those of the single-arc DED part. The joint areas of the multi-arc DED show a disordered distribution of α phase, in contrast to parallel α phases distributed in the base area, as well as the single-arc DED part. Thus, our work paves a viable way for the efficient and low-residual-stress fabrication of large-sized titanium alloy parts by the parallel multi-arc DED pathway.