Microstructure Uniformity and Mechanical Property Fluctuations in Large-Size Ti-46Al-8Nb-2.5V Ingot with β Solidification Mode

A large-size ingot (Φ200 mm × 800 mm) with the nominal composition Ti-46Al-8Nb-2.5V (in at.%) was fabricated via triple vacuum consumable electrode arc remelting in this study. XRD, SEM-EDS, TEM, tensile testing, and chemical analysis were employed to examine phase composition, microstructure, mechanical properties, and impurity contents across the height direction of the large-size ingot. Phase composition differences across different positions arose from the solidification path and elemental distributions. The redistribution of major elements during solid–liquid, allotropic and eutectoid transformations contributed to three types of segregation—namely S-segregation, β-segregation, and α-segregation. The maximum deviations in Al, Nb and V content along the height direction of the ingot were 2.05 at.%, 2.24 at.%, and 0.36 at.%, respectively. The bottom position of the ingot exhibited superior tensile properties at both room and elevated temperatures. The average oxygen and nitrogen contents in the ingot were 717 wt. ppm and 183 wt. ppm, respectively.