Abstract: The demand for metal additive manufacturing in the extreme environment of space orbital cabins is addressed. A metal laser direct writing additive manufacturing process adaptable to vacuum, high- and low-temperature conditions outside orbital cabins is developed. Experiments are conducted under vacuum normal temperature, vacuum low-temperature (-120 ℃), and vacuum high-temperature (107 ℃) conditions using a ground-based simulation experimental platform. Results show that the manufactured metal thin-walled cylindrical specimens have smooth surfaces without obvious macro defects, demonstrating the stability and repeatability of this process in vacuum and temperature extreme environments. Under the three conditions, the cylindricity of the thin-walled cylinder’s outer surface ranges from 0.167 to 0.383 mm, the maximum positional deviation ranges from 0.114 to 0.226 mm, and the mean surface roughness is less than or equal to 8.36 μm, confirming the good forming accuracy of this process. Microstructure analysis indicates that environmental temperature significantly affects the cooling rate of the thin-walled cylinder, leading to marked differences in microstructure morphology across conditions. Notably, the microstructure is finer and more uniform under vacuum low-temperature conditions, while high-temperature conditions promote an increase in microstructure size. This confirms the influence of environmental temperature changes on the microstructure of the specimens and the potential for future microstructure regulation via environmental temperature. This study provides a significant reference for metal additive manufacturing and the repair of extravehicular metal parts in the extreme conditions of space orbital cabins.

Key words: space manufacturing, in orbit manufacturing, metal additive manufacturing, extreme manufacturing, laser manufacturing