Effects of ultrasonic peening treatment layer by layer on microstructure of components fabricated by wire and arc additive manufacturing

Abstract

To improve the coarse grains of Al alloy, the ultrasonic peening treatment layer by layer was used during wire and arc additive manufacturing process of Al alloy. The severe deformation layer of last deposited layer was remelted when a new layer was deposited. In an Al alloy component, the matrix and transition layer were formed alternately. The pore was compressed under the effect of ultrasonic peening treatment, which led to a decrease of pore diameter. The equiaxed grain area was formed due to the anisotropy in grain growth and the increase of nucleation particles. In equiaxed grain area, the grains with a diameter of 200–400 nm, dislocation wall and dislocation tangle were formed.