Effect of Fe Content on the Microstructure and Properties of Additively Manufactured TC4 Titanium Alloy

Abstract:

Densely moulded sedimentary specimens without tissue defects were prepared by laser melting and deposition of titanium-based powders. The effects of Fe content on the microstructure, phase type and content and mechanical properties of TC4 specimens in the as-deposited state were investigated. The results show that with the addition of Fe, the size of α-Ti decreases, the net-basket microstructure is refined, and the as-deposited specimens are transformed from robust columnar crystals to fine and uniform equiaxial crystals in the forming direction. The average grain size of the specimen with 3wt% Fe is 160.6 μm, which is about 76% smaller than that of the specimen without added Fe. Combined with the XRD results, it can be obtained that the microstructure of the specimen consists of a large amount of α-Ti and a small amount of β-Ti, and the content of β-Ti increases slightly with the addition of Fe. The addition of Fe can significantly improve the tensile properties of the specimens, in which the tensile strength and yield strength of 3wt% Fe specimens are increased by 15.5% and 18.0%, respectively, and the post-break elongation is increased by about 60% compared with those of TC4. However, the impact toughness of the specimens in the as-deposited state with the addition of Fe is slightly decreased.