High-temperature deformation of delta-processed Inconel 718

Abstract

© 2017 Elsevier B.V. The hot-flow behavior of Inconel 718 subjected to delta processing (DP) was analyzed. Hot compression tests were subsequently performed at 960 °C and 1020 °C at the four different strain rates of 0.001, 0.01, 0.1, and 1 s-1. The two deformation temperatures were located below and above the d-solvus of IN718 respectively. Microstructural characterization was performed by means of optical (OM) and scanning electron microscopy (SEM). The high temperature deformation results in the fragmentation of the existing d-phase by means of partial dissolution and/or deformation, leading to an improved grain size control. A classic dynamic recrystallization (DRX) behavior was observed in the flow curves, which is typical of low-medium stacking fault energy (SFE) alloys. This flow behavior was modeled according to various approaches. Peak stress modeling was performed using two different approaches, referred to as ‘apparent’ and ‘physically-based’. The hot-flow behavior before the peak stress was modeled according to the Estrin-Mecking-Bergstrom approach, with Avrami kinetics employed to describe the DRX behavior.