Experimental Study of Low-Temperature Directed Energy Deposition Near Freezing Point Temperature 0°C

In this research, directed energy deposition (DED) experiments were conducted for the first time near freezing point temperature of 0°C. The objective was to demonstrate the on-site repair and remanufacturing capabilities using the DED process in cold environments like in the Northern Hemisphere in winter. The DED ambient and substrate temperatures were reduced to mimic the on-site DED process performed near freezing point temperature. Six single-track samples were printed at two different ambient temperatures (three samples printed at 20°C and another three samples printed at − 3°C) with 316L stainless steel powder. The molten pool evolution, sample geometries, internal crack, and hardness were investigated. It is found that at cold ambient temperatures, the DED process can be performed smoothly, and there was no obvious crack in the samples printed near the freezing point. The DED deposition at − 3°C had a larger melt pool zone and generated greater deposition height. In addition, at the temperature of − 3°C, the deposited samples had higher hardness values. Based on these experimental findings, it was concluded that the DED process can be performed near freezing point temperature, and the printed part is larger in size with better mechanical strength.