Material Anisotropy of non-heat-treated Inconel 718 Additively Manufactured by Wire Arc Additive Manufacturing

Material anisotropy is an important topic to consider when using additive manufacturing for industrial applications. Since the products fabricated by wire arc additive manufacturing (WAAM), a metal additive manufacturing technology used to fabricate large parts, are sometimes used in parts that require a specific level of strength required by industry, it is essential to clarify the characteristics of these products for their industrial application. Furthermore, it should be noted that the fabrication of complex shapes such as blades by WAAM cannot be used for industrial applications, because of defective fabrication if appropriate fabrication conditions are not used. However, many studies have focused on simple shapes such as flat plates; thus, there is a problem in that evaluations have not always been conducted under conditions that enable the fabrication of complex shapes. In this study, an investigation was conducted into the material anisotropy of Inconel 718 under conditions where impeller blades can be fabricated by WAAM. An Inconel 718 wall was fabricated by WAAM, and tensile specimens were cut from the wall. Two different directions were used for the cutout: vertical and horizontal. Tensile tests were performed using these two types of specimens with different cutout directions. A comparison of the tensile test results showed that the difference between tensile strength and elongation at break was less than 3%. This indicates that the material anisotropy of Inconel 718 without heat treatment is small compared to other materials additionally produced by WAAM.