Characterization on hot deformation behavior of Ti-22Al-25Nb alloy using a combination of 3D processing maps and finite element simulation method

In hot deformation behavior, two indispensable parameters which are power dissipation efficiency (η) and flow instability domains (ξ) in the processing maps have been exploited in most of literatures. However, rarely caught sight of dynamic distribution of η and ξ. In this study, hot deformation behavior of Ti-22Al-25Nb alloy was investigated by using a combination of three-dimensional (3D) processing maps and finite element (FE) simulation to unveil the variations of η and ξ with temperature, strain and strain rate during hot forming process. The hot compression tests were performed in the temperatures range of 995–1075 °C and strain rates from 0.001 to 1.0s⁻¹. According to the basic experimental data of isothermal compression tests, the intrinsic workability relevant to this alloy was evaluated comprehensively on the basis of true stress-strain curves and 3D processing maps. Moreover, the recommended processing domains are predicated to be within the temperatures range of 1050–1065 °C and strain rates range of 0.01–0.1s⁻¹, with a peak efficiency of 55%. The results of FE simulation show spatial distribution regularities of η and ξ in the specimens corresponding to the three characteristic districts during compressive deformation process. In addition, microstructure observations indicate a reasonable correspondence between hot processing parameters and microstructure evolution.