Microstructure and mechanical properties of bulked-wall Inconel 625 through wire and arc-based additive manufacturing

Abstract

In this study, Ni-based Inconel 625 bulk structures with several beads in each layer were manufactured by cold metal transfer based-wire arc additive manufacturing (WAAM) with different heat inputs and active interpass cooling. The macro- and micro-structures, and mechanical properties of the fabricated components were analyzed, especially bulk texture and micro texture were explored in detail. Distinctive from the often-observed strong (200) crystallographic texture in additively manufactured Ni-based alloys, a relatively weak bulk texture was achieved in the produced materials based on neutron diffraction measurements. Consistent with the bulk texture, a random micro-texture was found using the microscopical technique. The dendrite arm spacing of the sample with the lowest heat input was slightly decreased, and precipitates appeared to be lessened, together with refined texture, higher geometrically necessary dislocation density and more low-angle grain boundaries. All these factors promoted enhanced mechanical properties of the lowest heat-input sample (more than 10% higher), compared with other heat-input ones. Some void defects were observed at the bead overlapping areas at layer boundaries, and this is considered due to lack of fusion, and refined surface finish induced by lower heat input contributes to fewer voids. In addition, bulk walls are compared with single-bead walls, and bulk ones possessed about 100 MPa (horizontal) higher tensile strength but more obvious anisotropy than single-bead structures. This work provides insightful knowledge on the micro and macro texture, as well as other microstructural evolution and mechanical properties under various heat inputs in the WAAM of Inconel 625 Ni-based alloy, which contributes to the fabrication of large-sized components by WAAM with high effectiveness. Copyright © 2025, The Author(s), under exclusive licence to Springer Nature Switzerland AG.