Speaker
Description
Electron beam powder bed fusion (E-PBF) is an additive manufacturing process that allows for the production of individual metal parts with a high geometric freedom. This work adds another degree of freedom to the method by addressing the transition from processing a single alloy powder to a mixture of different powder compositions, which is termed as multi-material powder bed fusion.
For a better understanding of the process, especially in terms of consolidation and liquid phase mixing, simulations are powerful tools. Therefore, we extended the in-house developed simulation software S𝔸𝕄PLE2D (Simulation of Additive Manufacturing on the Powder scale using a Laser or Electron beam) by a multi-material module, which includes additional physical effects like diffusion and the corresponding enthalpy diffusion, Marangoni stresses and concentration-dependent material parameters.
This is applied to investigate the in-situ alloying of CuCr, which is the simultaneous processing of a mixture of elemental Cu and Cr powders. CuCr alloys are largely used for switching contacts and can be in-situ alloyed during E-PBF to achieve small, uniformly distributed Cr precipitates and reduce production costs.
Preliminary results show that the most important influence on the melting behavior and thus on the defect generation is the difference of the melting temperatures between the two powders. This leads to a division of the melt pool into two regions: An inner well-mixed one, surrounded by an outer region where only the lower-melting component is molten. Directly linked to this are further new challenges like locally varying depths of fusion and unmolten particles inside the part. Thus, a need for novel process strategies is expected.
| Speaker Country | Germany |
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