Microstructure and mechanical properties of pure copper manufactured by selective laser melting

Selective laser melting (SLM) was used to fabricate copper samples under various processing parameters. The influence of laser linear energy density on the microstructures and mechanical properties of the SLM copper samples were investigated theoretically and experimentally. Based on the results, the optimal linear energy density that can result in the best relative density (99.10 +/- 0.5%) and surface roughness (Ra = 12.72 +/- 4.54 mu m) was determined to be 0.50 J/mm which corresponds to the laser power and scanning speed of 200 W and 400 mm/s, 300 W and 600 mm/s, respectively. Under the optimal processing conditions, the microhardness and strength (i.e., yield strength and ultimate tensile strength) of the copper sample achieved the highest value. In addition, it is also found that the microstructure of the SLM pure copper samples was characterized by polycrystalline grains with columnar dendrites and equiaxed structures dispersed inside. The grain size showed a decreasing trend as linear energy density increased due to the improved intrinsic heat treatment effect. The paper proves that nearly full dense copper with desirable mechanical properties can be fabricated through SLM.