Comparison between numerical simulation of semisolid flow into a die using FORGE© and in situ visualization using a transparent sided die

Abstract

Semi-solid processing is a promising forming process for shaping metallic alloys in one shot. Numerical simulations are of great interest for optimizing the process. Generally, numerical simulation results are compared with interrupted flow experiments but these do not fully reflect the progress of material into the die because of the inertia of the flowing material which continues to move after the interruption to the shot. Results are available for in situ visualization of flow using transparent sided dies. Here die filling with a 90◦ change of flow path was simulated using the FORGE© finite element code and a constitutive equation based on a micro-macro modelling approach. The predicted flow behaviour was compared to the in situ visualization images obtained with a transparent glass sided die and reported in the literature. The impact of the presence of an obstacle, ram speed and friction coefficients on the material flow front is discussed. The initial solid skeleton is broken as soon as the material is deformed. The effect of the ram speed on the flow front is successfully represented by keeping the same parameters for the constitutive laws but requires a change in the friction coefficients. Friction modelling using the Coulomb law limited by Tresca cannot represent the ram speed effect on experimental friction conditions for the in situ visualisation tests used for the comparison here. However, the effect of an obstacle within the die on the material flow front is predicted well.