Synchronous-hammer-forging-assisted wire arc additive manufacturing Al-Mg alloy

The plastic deformation-assisted wire arc additive manufacturing (WAAM) technology based on the hammer-forging method has essential application prospects in preparing high-dense fine-grain aluminum alloy components. However, the existing interlayer hammer-forging method has limitations, such as insufficient hammering force and high demand for hammering times when obtaining large plastic deformation. To effectively solve these problems, this paper proposed synchronous-hammer-forging-assisted WAAM technology and systematically studied its effects on the macroscopic morphology, microstructure, pores evolution, and mechanical properties of WAAM Al-Mg alloy specimens. The results show that under the synchronous hammer-forging (SHF) condition, a large plastic deformation of 33.97% can be achieved by the 80 N hammer forging force, and the surface flatness of the specimen was significantly improved. The grain size of the specimen was reduced from 105.92 µm in the deposited state to 37.15 µm in the hammered specimen by 64.93% with a significant equiaxed effect. Simultaneously, with the application of SHF technology and the increasing hammer-forging force, the precipitated phase dominated by Al3Mg2 was broken. The pores in the specimen changed from round to narrow and elongated shape with only 0.0065% porosity. The number of pores, equivalent diameter, and surface area were reduced by 68.33%, 13.75%, and 67.24%, respectively. The yield strength and ultimate tensile strength of the hammer-forged specimens reached 250.37 MPa and 315.03 MPa, respectively, which were 36.28% and 8.95% higher than those of the deposited specimens, and still maintained a high elongation rate of 36.11%.