Wire arc additive manufacturing of Inconel 718 inclined thin-walled walls: Inducing the occurrence of multiple fracture behavior of δ phases to significantly improve room-temperature tensile properties

Based on the simplified grain model, δ phases with slender morphology continuously distributed along columnar grain boundaries were more prone to multiple fracture behavior under external loading perpendicular to grain boundaries. Different from slender δ phases at grain boundaries, this study innovatively found that the intragranular uniformly distributed lamellar δ phases tend to grow along the (-1-11)γ plane trace, and multiple fracture behavior always occurs preferentially in those δ phases grown along the (-1-11)γ plane trace.

This study provides powerful experimental support and theoretical basis for the recently proposed secondary strengthening phenomenon of δ phase, which is expected to use this phenomenon to design a new post-treatment scheme in subsequent work to further improve the strength and plasticity of WAAM IN718 alloy.