Modelling and researching the evolution of stress during arc-directed energy deposition (ADED) hybrid inter-layer hammering

Hybrid manufacturing of arc-directed energy deposition (ADED) and inter-layer hammering can build components with low detrimental residual stress (RS) and warping. Inter-layer hammering with lower load demand has proved to be a promising technology to improve the microstructure and mechanical properties. In this paper, a finite element model of the ADED hybrid inter-layer hammering was constructed for the first time. The accuracy of the model is evaluated by comparing thermal history, RS, and warping. The results show that the maximum compressive RS -25Mpa appears at 3 mm from the top of the wall after a single inter-layer hammering. The RS of the inspection position is reduced by 74.6% after six layers of hammering compared with the wall manufactured by ADED alone, and low-stress distribution with a value of -30Mpa appears in the range of 7 mm to 15 mm from the substrate surface. The warping of the wall in the building direction was completely suppressed (from 0.21 mm to 0 mm). In addition, the plastic strain introduced by the hammering at the wall top exacerbates the "misfit" between the regions of the wall top, resulting in tensile stress at the wall top.