The directed energy deposition (DED) process of metal 3D printing technologies has been treated as an effective method for welding, repairing, and even 3-dimensional building of machinery parts. In this study, stainless steel 316L (STS316L) and Inconel 625 (IN625) alloy powders are additively manufactured using the DED process, and the microstructure of the fabricated STS316L/IN625 sample is investigated. In particular, there are no secondary phases in the interface between STS316L and the IN625 alloy. The EDS and Vickers hardness results clearly show compositionally and mechanically transient layers a few tens of micrometers in thickness. Interestingly, several cracks are only observed in the STS 316L rather than in the IN625 alloy near the interface. In addition, small-sized voids 200– 400 nm in diameter that look like trapped pores are present in both materials. The cracks present near the interface are formed by tensile stress in STS316L caused by the difference in the CTE (coefficient of thermal expansion) between the two materials during the DED process. These results can provide fundamental information for the fabrication of machinery parts that require joining of two materials, such as valves.

Abstract
1. 서 론
2. 실험방법
3. 결과 및 고찰
4. 결 론
References

• 엄영성(재료연구소 분말/세라믹연구본부) | Yeong Seong Eom (Powder/Ceramic Division, Korea Institute of Materials Science)
• 김경태(재료연구소 분말/세라믹연구본부) | Kyung Tae Kim (Powder/Ceramic Division, Korea Institute of Materials Science) Corresponding Author
• 정수호(재료연구소 분말/세라믹연구본부) | Soo-Ho Jung (Powder/Ceramic Division, Korea Institute of Materials Science)
• 유지훈(재료연구소 분말/세라믹연구본부) | Jihun Yu (Powder/Ceramic Division, Korea Institute of Materials Science)
• 양동열(재료연구소 분말/세라믹연구본부) | Dong Yeol Yang (Powder/Ceramic Division, Korea Institute of Materials Science)
• 최중호(재료연구소 분말/세라믹연구본부) | Jungho Choe (Powder/Ceramic Division, Korea Institute of Materials Science)
• 심철용(㈜인스텍 연구소) | Chul Yong Sim (R&D Division)
• 안승준(㈜인스텍 연구소) | Seung Jun An (R&D Division)