レーザ積層造形における純銅の溶融凝固現象解析による造形条件の最適化

抄録

Pure copper is used as a material for products with complicated shape, such as electrical components and heat exchangers because of having the high electrical conductivity and the high thermal conductivity. Particularly, in a heat exchanger, more complicated shape is required in order to improve heat conductivity. Therefore, recently the additive manufacturing (AM) technology is applied to manufacture a heat exchanger. AM is a prominent technology in the industrial fields such as aerospace, medical, automotive and so on. It is however difficult to fabricate high-density pure copper objects by the selective laser melting (SLM) process. One of the reasons is considered to be its high thermal conductivity by which the heat in the melt pool rapidly diffuses away. Additionally, the energy absorption rate of pure copper for the wave length of the Yb-fiber laser makes the size of melt pool smaller. In this research, the optimum fabrication condition of high-purity 99.9% copper fabricated by SLM process was investigated by evaluating the density and microstructure of the as-built specimens. As a result, it was found that the optimum process parameters of laser power and scan speed are 800W and 300 mm/s, and the optimum energy density is around 1000 J/mm³, which is much higher than that of other materials due to high reflectivity and high thermal conductivity of pure copper. The high density parts were successfully fabricated by the optimum fabrication condition. The maximum density of the as-built specimen was 95.5%.