Effects of annealing on microstructure and deformation uniformity of Ti-22Al-24Nb-0.5Mo laser-welded joints

Publication date: 15 September 2017
Source:Materials & Design, Volume 130
Author(s): Xueyan Jiao, Beibei Kong, Wang Tao, Gang Liu, Hanwei Ning
In order to improve the deformation uniformity between base metal and weld zone, the laser-welded joints of Ti-22Al-24Nb-0.5Mo alloy were subjected to different annealing treatments at 980°C, 1030°C and 1080°C, respectively. The microstructure and tensile behavior of the joints under as-welded and annealed conditions were systematically investigated. Results show that the microstructure and mechanical properties of the laser-welded joints are found sensitive to the annealing conditions. During the annealing processes, the static recrystallization of B2 phase occurred in base metal with the phase transformations from O to B2 and α2 to B2. In fusion zone, the α2 phase precipitated within the columnar B2 grains except the annealing at 1080°C. The microstructural inhomogeneity between base metal and weld zone has been effectively reduced by the annealing above 1030°C. Besides, the tensile tests at 970°C reveal that annealing treatment has significantly improved the deformation uniformity in weld joints, for example the maximum deviation rate from average effective strain for the joints annealed at 1030°C was reduced to 0.15. Overall, the annealing process at 1030°C is suggested as the appropriate heat treatment to obtain the uniform deformability in laser-welded joints.

Graphical abstract

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