Despite the increasing insights achieved on their microstructure-property correlation, safe applications of additively manufactured (AMed) Ni-base superalloys are quite limited due to several factors, including the lack of predictive models that can link the process-induced microstructural characteristics to the mechanical behaviour of these materials. In the case of AMed Inconel-718 (IN718), a considerable amount of research has been devoted to characterizing and understanding the elastic and inelastic properties. However, the observed anisotropic creep behaviour and the corresponding deformation mechanisms have not been investigated sufficiently so far, despite the great relevance of creep properties for industrial applications.    

In the present work, we have combined a set of systematic experiments and modelling to address creep anisotropy and its correlation with microstructural characteristics in laser-based powder bed fusion (PBF-LB/M) additively manufactured IN718. We have performed creep tests on specimens in three build orientations at 650°C, carried out EBSD measurements for each orientation, and utilized a multiscale approach to model observed creep anisotropy based on microstructural characteristics. The modelling framework utilizes crystal plasticity (CP) combined with polycrystalline representative volume elements (RVEs). The CP model has been developed specifically for the γ’’-strengthened IN718 and the material parameters have been fitted based on single crystal creep tests. Various polycrystalline representative volume elements (RVEs) models have been considered with an increasing level of complexity. The effect of crystallographic texture, grain morphology and grain boundary sliding on creep anisotropy has been investigated.