Flow Stress Modeling in a γ-γ/ Cobalt Base Superalloy by Using the Hyperbolic Sine Equation and ANN Method

The new class of wrought γ-γ/ Co-base superalloys, which are based on Co-Al-W system,  was developed by conventional hot working routes with a high volume fraction of γ/ precipitates and good mechanical properties. The aim of the present study was to predict the flow stress and hot deformation modeling of a novel γ-γ/ Co-base superalloy. The hot compression tests were carried out over a wide range of temperatures (950°C-1200°C) and strain rates (0.001s-1-1s-1). The flow stress analysis, constitutive approach and microstructure characterization revealed that dynamic recrystallization (DRX) occurred at a high temperature regime (1100°C-1200°C) but not at a low one (950°C-1050°C) due to the presence of γ/ precipitates. The hot deformation characteristic was studied using the hyperbolic sine equation on each of the above-mentioned regimes and the ANN approach on the overall conditions. The constitutive method indicated good potential for the prediction of the flow stress at each separated regime, but the ANN model represented a much more appropriate performance. The outstanding predictability of the ANN model regardless of the γ/ phase participation during the thermomechanical processing under the overall deformation conditions can be considered as another achievement of the proposed approach.

Keywords:

γ-γ/ Co-base superalloys , Hot deformation modeling , Flow stress prediction , Hyperbolic sine equation , ANN