Influence of Processing Parameters on the Grain Morphology and Crystallographic Texture of Inconel 625 Fabricated by Laser Powder Bed Fusion

Résumé fourni par la source

Abstract Although volumetric energy density (VED) is widely used to correlate manufacturing parameters with the microstructural characteristics of Inconel 625 (IN625) produced by laser powder bed fusion (LPBF), its ability to adequately represent microstructural evolution remains limited, since different combinations of process parameters can result in distinct thermal conditions and, consequently, different microstructures for the same VED value. In this context, the present study investigated the individual effects of laser power, hatch spacing, and exposure time on the grain morphology and crystallographic texture of LPBF-fabricated IN625. Samples were produced by LPBF using an experimental design based on the individual variation of laser power (180, 200, and 220 W), hatch spacing (80, 90, and 100 µm), and exposure time (60, 70, and 80 µs), including conditions with equivalent VED values. Microstructural characterization was performed using optical microscopy, scanning electron microscopy, x-ray diffraction, and EBSD. The results showed that increasing laser power promotes columnar grain growth, increases the density of geometrically necessary dislocations (GNDs), and intensifies the {001}<100> texture, whereas reducing hatch spacing promotes grain refinement and the predominance of the {011}<100> orientation. Exposure time mainly influenced the intensity of the crystallographic texture and the crystal lattice relaxation mechanisms. Of particular relevance, samples produced with equivalent VED values exhibited significant differences in grain morphology, GND density, and crystallographic texture, demonstrating that the microstructural response is not determined exclusively by the applied volumetric energy input. These findings demonstrate that the use of VED as a single parameter may mask the individual effects of processing parameters, highlighting the need for an approach based on the isolated analysis of each variable to predict and control the microstructure of LPBF-fabricated IN625.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.