Evaluation of the hot workability corresponding to complex deformation mechanism evolution for Ti-10V-2Fe-3Al alloy in a wide condition range

The hot workability of as-forged Ti-10V-2Fe-3Al alloy was evaluated. Meanwhile, the intrinsic relationships between deformation mechanisms and processing parameters were determined by the processing maps on the basis of dynamic materials model (DMM) with the input stress-strain data collected from a series of isothermal compressions at temperatures of 948-1123 K (across β-transus) and strain rates of 0.001-10 s−1. At the beginning, at a set of discrete true strains the response maps of strain rate sensitivity exponent (m-value), power dissipation efficiency (η-value) and instability parameter (ξ-value) to temperatures and strain rates were developed respectively. Following that, a processing map corresponding to each true strain was constructed by superimposing an instability map over a power dissipation map. According to m-criterion, η-criterion and ξ-criterion, the stable regions with higher power dissipation efficiency (η > 0.3) and unstable regimes with negative strain rate sensitivity exponent and instability parameter (m < 0 and ξ < 0) were clarified clearly. Moreover, the deformation mechanism map was established, based on which the parameter domains corresponding to different deformation mechanisms were identified. By the criteria of two main stable strain-softening mechanisms, i.e. globularization and dynamic recovery (DRV), the globularization-predominant parameter domain in α+β-phase temperature range and DRV-predominant parameter domain in β-phase temperature range were identified and recommended. In a wide temperature range across β-transus and a large strain rate range, the clarification of stable and unstable parameter regions corresponding to different deformation mechanisms contributes to design in the various hot forming processes of Ti-10V-2Fe-3Al alloy without resorting to time-consuming trial-and-error procedures.