MSU.CAVS.CMD.2008-R002: Modeling the Hot Forging of Nickel-Based Superalloys: IN718 and IN718Plus.

Marin, E., El Kadiri, H., Lowry, A., Wang, P., & Horstemeyer, M. (2008). MSU.CAVS.CMD.2008-R002: Modeling the Hot Forging of Nickel-Based Superalloys: IN718 and IN718Plus.

This document is the final report related to the work performed by the Center for Advanced Vehicular Systems (CAVS) at Mississippi State University in the contex of the project entitled “Optimal Design of Materials Processes”, a project sponsored by the Air Force Research Laboratory (AFRL) and conducted by Miltec Research and Technology. This final report presents the use of an internal state variable material model to describe the rate– and temperature–dependent large deformation response of the nickel-based superalloys Inconel 718 and Inconel 718 Plus. The particular version of the material model treated here describes the elastic-plastic and thermal deformation of metals, having two internal state variables whose evolution equations account for dislocation hardening and static /dynamic recovery processes. Other microstructural features such as recrystallization and grain growth are not included in this version of the model. Experimental data from mechanical characterization tests of cylindrical and double cone compression specimens are used to both calibrate the material model and validate its predictive capability. In general, the calibrated model predicts the experimental stress/load levels as well as the rate and temperature dependence of the mechanical response of these superalloys, although the softening behavior shown by the data is not captured. Microstructural studies of the deformed specimens have also been carried out to characterize their grain morphology, and are presented in this report as well.