From powder to a sintered metal part - a numerical simulation

The finite element analysis and the discrete element method for simulating the powder compaction.

Finite element analysis (FEA) for simulating the powder compaction and sintering commonly has to make use of an initial assumption about the powder filling density and its corresponding distribution in the mold. Therefore, FEA may not be able to predict sintering shrinkage and distortions accurately if an inhomogeneous powder filling density is present in practice which, because of lack of knowledge, has to be approximated by a homogeneous one in the finite element model for the entire powder body in the as-filled state. Futhermore, this also influences in a non-beneficial way the FEA-based predictability of the deformed shape by subsequent hot forming.The discrete element method (DEM) is an adequate tool for mold filling process simulations. Filling density including spatial gradients as a result of powder manipulating steps can be simulated via DEM by also accounting for filling density influencing actions like mechanical vibration of the mold / powder body assembly. At the 19th Plansee Seminar Christian Grohs presentet how the filling density distribution simulated by DEM then can be used as input in an FEA model for the compaction and de-molding process thus yielding the density distribution of the green part. Based on the latter, inhomogeneous sintering shrinkage can be simulated by an FEA-based sintering shrinkage model this way yields the final shape of the as-sintered component. Finally, the results of the sintering simulations are transferred into an FEA model for hot rolling which yields the final shape of the as-deformed component. The applicability of the whole modeling workflow being applied to a large scale molybdenum component is demonstrated in the present paper.

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