Hot Working Flow Behavior of Ti-6242S Alloy

The hot working behavior of Ti-6242S alloy was investigated over a range of temperatures and strain rates (973–1,373 K and 10−3–1 s−1, respectively). The flow behavior was dominated by dynamic recovery and flow softening at temperatures above and below 1,223 K, respectively. Processing maps were constructed from the flow curves at a true strain of 0.5 over the temperature ranges 973–1,223 K and 1,223–1,373 K. In each temperature regime, we compared the flow localization parameter and temperature sensitivity with the instability parameter determined from the processing map. The processing conditions were optimized in the temperature range 1,173–1,273 K and strain rate ranges of 5.0 × 10−1–1.0 s−1 and (1.0–5.0) × 10−3 s−1. The deformation activation energy under a strain rate of 10−3 s−1 was determined as ∼360 kJ/mol and was further reduced when considering the threshold stress. The operating deformation mechanism in the 973–1,223 K regime was dislocation climb creep. The microstructural evolution was examined by optical and scanning electron microscopies and was correlated with the stable and unstable regimes of the processing map.