Decoupling build orientation-induced geometric and texture effects on the mechanical response of additively manufactured IN625 thin-walled elements

Abstract

When additively manufactured (AM) metallic components have highly anisotropic microstructures, the relationship between microstructure and mechanical properties becomes more complicated with the introduction of additional design parameters, such as build orientation and geometric variations. This study serves to decouple the contribution of build orientation-induced texture and geometric effects on the mechanical response of thin-walled Inconel 625 (IN625) T-elements fabricated by laser-based powder bed fusion and subjected to a combination of heat treatments. T-elements were printed at 40° and 90° inclinations from the build plate, which led to variation in crystallographic texture as well as a 10% ligament width difference. T-elements from both build orientations underwent a standard stress-relief heat treatment of 870 °C for 1 h, and subsets of these were homogenized at 1150 °C for 90 min. Milli-scale tests indicated that the 40° stress-relieved T-elements were 30% less stiff than their 90° counterparts due to both geometric and texture differences. Effective elastic tensor estimations from EBSD maps allowed the determination of the relative contributions of texture and geometry. Combined results for stress-relieved and homogenized samples indicate that the (+)10% change in ligament width led to a (+)38% change in the elastic response, while in-plane texture differences affected the elastic response by (−)8%. These findings highlight the importance of build orientation-induced geometric variation for the performance of printed-AM thin-walled structures in complex loading conditions.