Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7968949 | Materials Characterization | 2018 | 7 Pages |
Abstract
In this paper, the microstructure characteristic of a β solidifying TiAl alloy Ti-44Al-4Nb-4V-0.3Mo-Y (at. %) was investigated systematically. Cylindrical blanks were isothermal forged at 1250â¯Â°C within (αâ¯+â¯Î²) two-phase-field and 1200â¯Â°C within (βâ¯+â¯Î³) two-phase-field under the strain rate of 0.02â¯sâ1 and 0.03â¯sâ1, with a total reduction of 75%. The microstructure of the alloy forged in αâ¯+â¯Î² two-phase-field consists of lamellar colonies (only represents α2/γ lamellar colonies), mixture structure of β/B2 phase and γ phase as well as β/γ lamellae resulted from cellular reaction. However, a large amount of equiaxed γ grains appear with no β/γ lamellae available under forging in βâ¯+â¯Î³ two-phase-field, and the average size of γ grain is about 10â¯Î¼m. By further annealed at 900â¯Â°C for about 0.5â¯h, the structure of hot forging at 1250â¯Â°C is composed of β/B2 phase and equiaxed γ grains with the mean size about 5â¯Î¼m. After heat treated at 1200â¯Â°C for 2â¯h, the microstructure of this annealed samples is characterized by fine grained fully lamellar (FFL) structure with size of 20â¯Î¼m. A specially designed hot forging process is proposed, which prevents the existence of inhomogeneous lamellar structure.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
S.Z. Zhang, Z.W. Song, C.J. Zhang, J.C. Han, Y.B. Zhao, J.P. Lin, F. Yang,