Study of the microstructure and mechanical properties in multilayered structures created by Laser-PTA additive manufacturing

Abstract

This paper proposes a laser-assisted plasma transfer arc (Laser-PTA) additive manufacturing (AM) technology using coaxial powder flow. The focus of this paper is the effect of laser energy on the deposited microstructure, including grain morphology, texture characteristics, etc. The research focuses on the ultimate tensile strength (UTS), elongation properties, as well as anisotropy improvement of the deposition material. The experimental results show that laser energy, not less than 300 W～400 W, significantly promotes grain refinement and weakens the grain growth texture in deposition layers. The laser energy can cause the growth of equiaxed fine grains in the interlaminar region, which completely blocks the continuous growth of columnar grains in adjacent layers. Additionally, laser energy can also increase the proportion of high angle grain boundaries within the microstructure of the deposited layers. Optimizing the microstructure has a favorable effect on the mechanical properties of the deposited material's structure. The tensile test results showed that the vertical and horizontal UTS and elongations were improved, with a significantly higher vertical direction tensile improvement than that seen in the horizontal direction. At the same time, the UTS average difference between the horizontal and vertical decreased by 73.29%, and the elongation average difference decreased by 67.61%, which indicates the material has improved anisotropic mechanical properties.