Microstructure and Mechanical Properties of 600 °C High Temperature Titanium Alloy Fabricated by Additive Manufacturing

600 °C high temperature titanium alloy (AM-Ti150) samples were fabricated on forged Ti-6246 alloy by laser additive manufacturing with different linear energy densities. The microstructure characteristics and mechanical properties of the deposited layer and interface bonding zone were studied by SEM, XRD, TEM and tensile test, and the formation mechanism was discussed. The results show that the microstructure of AM-Ti150 alloy deposited layer is basketweave structure composed of α' martensite. In the range of linear energy density in this study, with the increase of linear energy density, the defects decrease, the density increases, the width of martensite lamellar increases, and the tensile strength and elongation at room temperature and high temperature increase. When the linear energy density is 90 J·mm-1, the density of AM-Ti150 alloy is 99.67%, the tensile strength and elongation at room temperature are 1075 MPa and 4.7%, respectively. And the tensile strength and elongation at high temperature are 808.7 MPa and 14.3%, respectively. Under the influence of heat source, the non-uniform structure of Ti-6246 alloy at interface bonding zone is formed from top to bottom, and the ghost structure is formed due to the insufficient diffusion of A l and Mo elements in the upper part. With the increase of linear energy density, the diffusion of Al and Mo elements are gradually sufficient, and the size of the ghost structure decreases. © 2022 Rare Metals Materials and Engineering Press. All rights reserved.