DED 공정을 이용한 AISI 1045 기저부위 AISI 1045 분말 대체적 적층시 적층부와 기저부 형상이 적층부 인근 열-기계 특성에 미치는 영향 고찰

Abstract

Recently, due to environmental and resource depletion concerns, researchers around the globe are actively involved in research and development of new methodologies to reduce impact of industrial activities on environment. The interest in the field of additive manufacturing (AM) is exponentially increasing due to its repair and remanufacturing capabilities. Repair and remanufacturing of damaged machine tool parts by AM can lower the operational cost by extending the life cycle of the metal parts. Directed energy deposition (DED) is a metal AM process. DED process can deposit metal on straight and inclined surfaces along the arbitrary trajectory. Hence, DED is suitable for repairing and remanufacturing of irregular shape machine parts. However, localized rapid temperature changes occur during deposition process due to high density energy source. The temperature gradients cause residual stress and displacement in remanufactured parts. The aim of this study is to investigate the effect of shape of deposition region, shape of the substrate, deposition strategy and pore location on thermo-mechanical characteristics in the vicinity of repaired region by DED. Finite element analysis (FEA) according to the substrate shape and shape of deposited region was performed in order to analyze thermo-mechanical characteristics of repaired metal parts. Various substrate shapes and deposition region shapes including the angle of inclination of the deposited region, the shape of the substrate with various space at the edge of deposited region, the shape of deposited bead with various width and inner radius of substrate were selected to predict residual stress and displacement in the vicinity of deposited region. Subsequently, FE analysis of deposition strategy was performed. Proper deposition pattern, interlayer time and interpass time were selected according to residual stress and displacement results. Occurrence of the pores during deposition by DED was considered in this study. Analysis models according to pore location was generated. Thermo-mechanical characteristics depending on pore location were predicted. Finally, proper parameters such as suitable substrate shape, shape of deposited region and proper process parameters were proposed.