In the recent years additive manufacturing (AM) has started to revolutionize classical production technology as it allows unique design possibilities at short process chains and small lot sizes. Even if the changes are far from having reached all fields of industrial fabrication, the process has started and it can be expected that the relevance of AM will steadily increase in the next years. Among various AM approaches, selective laser melting (SLM) of metals is most promising for industrial fabrication, as it allows the generation of fully functional machine and tool parts. Whereas for materials like aluminium, steel, titanium, nickel and cobalt chromium alloys SLM is already well established, its application for the processing of refractory metals still poses a significant challenge. Here multi-physical simulations are a powerful tool to gain a fundamental understanding for the processing of refractory metals by SLM, to develop the technology further and to open it up new fields of application.
In this contribution a thermo-fluid dynamical multi-phase simulation model for the SLM process shall be presented (see Figure 1). The model is based on the finite element software Comsol Multiphysics. It distinguishes between solid, liquid and molten metal as well as the ambient atmosphere. The multi-physical description includes the absorption of laser radiation on the metal surface, conductive and convective heat transfer in the metal and the atmosphere as well as phase transition processes. Based on the model an analysis of the influence of process parameters on process dynamics, defect generation and processing result in SLM of molybdenum is performed. The presented results show how line width and surface morphology during line and layer build-up are affected by laser power and energy input. The simulation results are in good accordance with experimental metallographic data.
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|Manuskript||Figure 1||Simulation of SLM of molybdenum||71 KB||Download|