Elevated Temperature Deformation of Cast Inconel 718

Abstract

The rate of coarsening of γ' and γ” particles was evaluated for Inconel 718. The elevated temperature deformation behaviour was studied through tensile tests at 430, 550 and 650°C combined with TEM studies of deformed structures. The coarsening kinetics for both γ' and γ” type particles are in good agreement with the LSW theory within the temperature range 550 to 750°C. Dynamic strain ageing contribute strongly to the deformation behaviour specially at 650°C but also at 430 and 550°C. The Bailey Orowan type of relation for dislocation slip and recovery provides an excellent means of describing the stress-strain behaviour when coupled with a model for the locking effect of diffusing elements to the dislocations. In spite of the simplifying assumption used the model gives a very good description of the experimental data for all conditions of testing. The dominating mechanism of particle strengthening is most probably a combination of APB cutting with the first dislocation in the pair completely flexible and as a consequence also coupled with some bypassing by the Orowan mechanism. © 1990, Walter de Gruyter. All rights reserved.