Effects of build direction and heat treatment on creep properties of Ni-base superalloy built up by additive manufacturing

The effects of build direction and heat treatment on the creep properties of Ni-base superalloy fabricated by additive manufacturing were examined at 650 degrees C. The creep rupture lives and ductilities of materials produced by additive manufacturing were lower than those of conventionally wrought material. The horizontal-direction specimen exhibited inferior creep life and worse ductility than the vertical-direction specimen because of the direction of the interdendritic delta-phase precipitates, which were arrayed perpendicular to the stress axis in the former specimen. The morphology and a row of interdendritic delta-phase with incoherent interfaces were found to affect the materials' creep life and ductility. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.