Factors influencing high-temperature and durable anisotropy of IN718 alloy formed by SLM

In order to study the influencing factors of the durable anisotropy of IN718 formed by selective laser melting (SLM), the printed state was subjected to solution treatment and aging (SA) and direct aging (DA) treatments. X-ray diffraction, scanning electron microscopy and electron backscattered diffraction were used to characterize the xOy surface and yOz phase, microstructure and texture of the two-state samples, and the transverse/transverse/ Longitudinal samples were tested for durability. After the test, the fracture and cross-sectional cracks were characterized and analyzed quantitatively. The study showed that the DA state sample retained the microstructure of the printed state to a large extent, with obvious traces of the melt pool. The grain size There is almost no change. There is a large amount of segregation in the microstructure, and XRD shows a peak of the MC phase with weak diffraction intensity. The grain size and distribution of the SA state sample are similar to those of the DA state sample, and there is a wide range of δ phase precipitation. The difference in the high-temperature durability performance of transverse/longitudinal specimens decreases with the decrease in the number of crack initiation points during loading. The difference in the molten pool structure and grain boundary structure perpendicular to the stress loading axis affects its high-temperature durability in all directions. The key factor of the opposite sex.