Process and performance of pure copper parts formed by blue laser directed energy depostion

High reflective metal materials have high absorptivity to short wavelength laser. In this paper, high-power blue laser is used as energy source to deposit pure copper on stainless steel substrate. The laser power, scanning speed and powder feeding rate are combined to form different process parameters on five levels for full factor test. Firstly, the influence of process parameters on the deposition layer was analyzed from the macro dimension, and then the multi-channel and multi-layer process was explored from the three aspects, including relative density, microstructure and mechanical properties. The results showed that continuous deposition can be performed when the laser energy per unit powder feed (LEPF) is in the range of 2.592 ~ 6.048 kJ/g. When the LEPF value is more than 6.050 kJ/g, the pores appear due to the excessive laser energy used. The pure copper thin-walled cylindrical part with good surface quality was printed with LEPF value of 4.53 kJ/g. Pure copper bulk samples with the highest relative density of 99.10% were obtained through orthogonal scanning, and two kinds of pores were observed: near spherical gas encapsulated pores (type I) and unfused powder pores (type II). Finally, tensile tests were carried out, and the results showed that, The tensile strength far from the base plate is 196.55 MPa, and the elongation after fracture near the base plate is 26.72%.