Understanding Inhomogeneous Mechanical Properties in PBF-LB/M Manufactured Parts Due to Inhomogeneous Macro Temperature Profiles Based on Process-Inherent Preheating

Abstract

The mechanical properties in laser-based powder bed fusion (PBF-LB/M) manufactured parts are anisotropic in nature due to the layer-wise build-up but also change due to different solidification conditions in dependence on the process strategy and the geometry. In this work, the latter effect is examined by means of simulating the thermal history on a part scale (macro temperature) and correlating the critical temperature and holding time with the local hardness and microstructure. A macro temperature model is introduced and validated with vector-based thermal simulations and thermo couple measurements from the build-up process. Two cone-shaped geometries are investigated, namely, an upright and an inverted cone. The examinations are performed and validated with Inconel 718. An outlook to further investigations and more complex, real-life applicable geometries is given.

Keywords

• additive manufacturing
• laser powder bed fusion
• finite element modelling
• microstructure
• Inconel 718