Directed Energy Deposition에서 흄의 생성 원인 및 대책

• Published in: 대한금속·재료학회지, 58(6) Vol. 58; no. 6; pp. 383 - 396
• Main Authors: 김강형, Kang-hyung Kim, 정찬현, Chan-hyun Jung, 정대용, Dae-yong Jeong, 현승균, Soong-keun Hyun
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 05.06.2020; 대한금속·재료학회
• Subjects: cavitation bubble; defects; fume prevention; metal additive manufacturing; nanoparticles; 재료공학
• ISSN: 1738-8228; 2288-8241
• DOI: 10.3365/KJMM.2020.58.6.383

Pores and cracks are known as the main defects in metal additive manufacturing (MAM), including directed energy deposition(DED). A gaseous fume is often produced by laser flash (instantaneous high temperature) during laser processing, which may cause various defects such as porosity, lack of fusion, inhomogeneity, low flowability and composition change, either. However the cause and harmful effects of fume generation in DED are known little. In laser processing, especially laser welding, many studies have been conducted on the prevention of fume because it generates defects that hinder uniform reactions between the laser beam and the materials. Generally, the fume occurs with easily vaporizing low melting point components or sensitive oxidizing elements. Unsuitable conditions are also known to have an effect, including laser power, travel speed, powder feed rate and shielding gas supply. Practically, there are many more fume generating factors in the DED process, and the lack of understanding requires a lot of trial and error. In this article the laser-related and weld metallurgy literatures were reviewed, focusing on the prevention of fume in powder DED. The causes of the fume, were explained to result from the stages of cavitation bubbles generated by the laser induced plasma and the nanoparticles released. Additionally, the effects of alloying components and environmental conditions for fume generation in the DED process were investigated, and suggestions are proposed to prevent fume. (Received March 20, 2020; Accepted April 12, 2020)