20. An Approach to Develop Hansel–Spittel Constitutive Equation during Ingot Breakdown Operation of Low Alloy Steels

The control of the final quality of a forged product requires an in-depth comprehension of quality of the initial casted ingot. Hot workability is an important property which can be evaluated by variation of strain, strain rate, and temperature. Modeling of forging process always needs to define constitutive models for the material involved. In this study, 42CrMo steel with dendritic microstructure was used to generate the flow stress curves. In order to provide accurate predictions of the thermal and mechanical parameters in the actual ingot break down operation, hot compression tests were carried out at uniform temperatures ranging from 1050 to 1200 °C and strain rates of 0.25–2 s⁻¹. Finally, Hansel–Spittel law was developed to represent the dependency of the material flow stress on strain, strain rate, and temperature. FE Simulation results reveal that the model is able to predict the adiabatic heating during deformation.