Simulation of microstructure evolution during WAM process

摘要: The development of microstructure during Wire-Based Additive Manufacturing (WAM) is of major interest for the Additive Manufacturing (AM) industry. The resulting geometry, mechanical properties, and quality of WAM parts are directly affected by the process conditions. Numerical simulations of WAM processes can predict and optimize the process settings (heat input, thermal conditions, eg, by pre-heating,…) and therefore speed-up the trial-and-error phase of the manufacturing process (first time right). The WAM process can be considered as a welding process accompanied by continuous heattreatment processes (during the build-up of walls the heat source is reheating and even partially remelting existing layers multiple times), the formation of the microstructure mainly depends on the temperature evolution in the part. Two modes of microstructure development are considered: grain nucleation and growth during solidification and growth/recrystallization in the solid phase. To compute grain size considering the interplay of nucleation and growth during solidification, the Interdependence (ID) model is used. Based on the initial grain size distribution, chemical composition, inoculant particles, among other influence factors, the evolution of the microstructure and hot cracking susceptibility during the cooling and reheating cycles of an AM process can be calculated. Both models have been implemented into the Finite Element (FE) solver LS-DYNA®. Depending on the current element temperature either of the two grain morphology models are activated. Here, the evolution of the microstructure including the hot cracking susceptibility during the …