J. Phys. IV France 09 (1999) Pr9-33-Pr9-42
A model describing microstructural evolution for Ni-base superalloy forgings during the cogging processC.A. Dandre1, S.M. Roberts1, R.W. Evans2 and R.C. Reed1
1 Rolls-Royce UTC, Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, U.K.
2 Interdisciplinary Research Centre, Department of Materials Engineering, University of Wales, Swansea, Singleton Park, Swansea SA2 8PP, U.K.
In this paper we consider the development of a computer modelling tool for the thermomechanical cogging of alloy Inconel® 718. The cogging process is used widely by suppliers of aerospace materials, to break down the ascast ingot microstructure to an acceptable level of refinement prior to disc forging. The commercially available viscoplastic finite element software Forge3® has been employed to simulate the cogging process and to calculate the variables such as temperature, strain-rate and effective strain. In addition, a microstructural model has been incorporated into the code, which relates the volume fraction of recrystallised material and the associated grain size, to the state variables. Since dynamic and static recrystallisation phenomena govern microstructural evolution in this alloy, the logic relating the recrystallisation regimes has also been incorporated into the code. In order to validate the process model, results are compared to maps of observed microstructure in the as-cogged billet.
© EDP Sciences 1999