Microstructural characterization and mechanical properties of Inconel 625 wall fabricated by GTAW-based WAAM using stringer bead and circular weave pattern

TL;DR: In this paper , the fracture morphology analysis revealed that all the specimens were fractured as a result of large plastic deformation, corresponding to ductile failure, and the absence of laves phases makes the fracture mode ductile.

Abstract: In this work, Inconel 625 alloy was used to manufacture walls using the Wire Arc Additive Manufacturing (WAAM) technology, which is based on Gas Tungsten Arc Welding (GTAW). The wall was fabricated using a circular weave and stringer bead pattern. Microstructural analysis and tensile characteristics were evaluated for both walls. Using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and elemental mapping, the fracture zones of the tensile specimens were examined. The microstructure is mostly made up of equiaxed dendrites, with the rare presence of continuous and discontinuous cellular dendrites along the cross-section. In tensile tests, circular weaved walls performed better than stringer bead walls. The circular weave specimen had an ultimate tensile strength (UTS) of 762 MPa in the horizontal and 722 MPa in the vertical orientations. Also, the Inconel 625 wall showed anisotropic behavior (5.3%) during tensile testing. The fracture morphology analysis revealed that all the specimens were fractured as a result of large plastic deformation, corresponding to ductile failure. Based on the EDS results, the fracture zone mainly consists of Ni and Cr with a small percentage of Nb and Mo. The absence of laves phases makes the fracture mode ductile. The elemental mapping shows uniform dispersion of Ni and Cr within the fracture region, further supporting the ductile failure mode.