Characterization of hot deformation behavior of alloy 617 through kinetic analysis, dynamic material modeling and microstructural studies

The hot deformation behavior of alloy 617 has been studied by performing hot compression in a range of temperatures (1173-1473 K) and strain rates (0.001-10 s−1). The peak flow stress found to increase with Zener-Hollomon parameter (Z) following a hyperbolic-sine function relationship whereas peak strain followed power-law type relationship with Z. The average activation energy for the entire hot deformation domain was estimated to be 481 kJ mol−1. The experimental stress-strain data has been used to develop processing map employing dynamic material model. The material exhibits a wide stable domain below 0.1 s−1 spanning over 1250-1473 K, with a peak efficiency of ~45%. Based on the processing map and subsequent microstructural observation, the optimum hot deformation domain of alloy 617 is identified as 1323-1423 K and 0.001-0.1 s−1. Furthermore, microstructural observation alone has revealed that a significant DRX with grain refinement could also be obtained at high temperature (>1373 K) and high strain rate (>1 s−1) domain although processing map has marked this region as unstable domain.