SUPERPLASTICITY RESEARCH OF Ti-23Al-17Nb ALLOY SHEET
FU Mingjie1(), HAN Xiuquan1, WU Wei1, ZHANG Jianwei2
1 Metal Forming Technology Department, Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024 2 High Temperature Materials Research Department, Central Iron and Steel Research Institute, Beijing 100081
Cite this article:
FU Mingjie, HAN Xiuquan, WU Wei, ZHANG Jianwei. SUPERPLASTICITY RESEARCH OF Ti-23Al-17Nb ALLOY SHEET. Acta Metall Sin, 2014, 50(8): 955-961.
Superplastic forming is one of effective method to solve the forming difficulty of Ti3Al based alloy. In this work, the superplasticity of Ti-23Al-17Nb alloy sheet under the conditions of 940~1000 ℃ and 1.7×10-3~5.5×10-5 s-1 are studied. The results show the elongation changes as a parabola with the deformation temperature increasing, and the maximum elongation obtained at 960 ℃ and 5.5×10-5 s-1 is 1447.5%. Deformation hardening period increases much more than soften period due to the increasing of element Nb under low strain rate. Compared with primary microstructure, the superplastic deformation could eliminate the texture, the lath-like α2 grains gradually disappeared, the α2 grains became more equiaxed, and the content and size of α2 grains are decreasing with increasing of deformation temperature, the volume fraction of α2 and B2 phase could reach the optimum deformation at 50∶50. A constitutive relationship based on the Zener-Hollomn parameter and Arrhenius equation was defined for the TAC-1B alloy, and the deformation activation energy Q=390.76 kJ/mol. The results could provide a theory basis for the design and control of TAC-1B alloy superplastic forming process.
