13 - Process monitoring and simplified FE modeling of LPBF melt-pools. Influence on the microstructures and mechanical properties of small Inconel 625 struts.
Abstract
The influence of build strategy and part size for the LPBF manufacturing of small objects still remains rather poorly documented, especially for struts with diameters less than 2 mm, which are basic components of any lattice structure. Therefore, the aim of the current work is to understand the influence of strut diameter and build strategy on melt-pool properties, and resulting microstructural and mechanical properties of small Inconel 625 struts. First, high-speed imaging of melt-pools was carried out with the use of a homemade open architecture L-PBF instrumented system. Second, a simplified solid finite element model was developed and confronted to experiments to estimate numerically the melt-pool dimensions, and thermal parameters (G (K.m-1), R (m.s-1), Vc (K.s-1)) at the solid/liquid interface. Third, microstructures and mechanical properties were analyzed and discussed, based upon local melt-pool features. Results suggest a strong link between the shape and size of the melt zone and the morphological and crystallographic texture of objects, especially for small struts (<0.5 mm) for which a strong morphological and <001> fiber texture is obtained. Strategy effects are also shown, with clear differences between outside-in and inside-out contour strategies. Moreover, the model allows correlating the cooling rates with the solidification cell size, particularly in relation to scan strategies and struts diameter. Tensile properties for various diameters and strategies are then discussed considering all the metallurgical contributions to strengthening, including the high dislocation density estimated with both XRD and EBSD-KAM analyses. This work provides a useful insight for optimizing the L-PBF process when applied to small struts used in structure lattices, and achieving desired properties in the final product. Altogether, the combined “instrumented LPBF / numerical modelling / post mortem analysis” approach also offers a powerful tool to improve the quality of L-PBF parts and better understand their final properties.
Speaker
Patrice Peyre
Discover speaker profilePIMM, UMR 806 CNRS-Cnam-Arts et Métiers, Paris, France
Conference
13 - Process monitoring and simplified FE modeling of LPBF melt-pools. Influence on the microstructures and mechanical properties of small Inconel 625 struts.
Date/Time
20/03/2024
11:15 am -11:35 am
Location
Room 6