직접 에너지 적층 공정으로 제조된 인코넬 718과 스테인리스 316L 경사기능재료의 특성에 관한 연구

Abstract

Directed energy deposition (DED) is an additive manufacturing technology trough repetitive melting and cooling processes in which a high-energy laser beam is irradiated over a substrate or previously layered area while simultaneously spraying metal powder to the beam focusing area. In fact, although the DED has the specific advantage of being able to combine multiple materials to a target area, however, the process makes inevitably defects, especially at the interfacial boundaries between the materials due to the differences in the physical properties. In this respect, a functionally graded material (FGM) can be sued to solve the intrinsic problem because the composition of the materials along the deposited positions can be changed to avoid the formation of the defects and thus modified to design the mechanical properties of the FGM as well. The purpose of this study is to combine different two materials (stainless steel 316 and inconel 718) with the functionally graded structure (thus, the compositional properties of both materials at the same time) using the DED process. Before the process, the optimal conditions for the additive manufacturing and mechanical properties of each stainless steel 316L and inconel 718 were evaluated and then compared with references. Thereafter, the stainless steel 316L on the inconel 718 was directly deposited with the functionally graded composition, changing to each 25 and 10 wt%. The mechanical properties were evaluated at each composition and position between inconel 718/stainless steel 316L, especially reminding the presence of the defects.