Influence of SLM printing parameters and hot isostatic pressure treatment on the structure and properties of CuNi3Si1 alloy

Abstract

CuNi3Si1 is a precipitation-hardenable copper alloy exhibiting a favorable combination of high mechanical strength and electrical conductivity, sought after in the electrical and automotive industries. In this paper, a Selective Laser Melting process was applied to assess the effect of printing parameters on the structure and properties of this alloy. First, the acquired samples were investigated to determine their microstructure and optimize printing parameters. Furthermore, tensile testing, salt spray testing and potentiostatic measurements were carried out to estimate the application potential of the 3D-printed copper alloy. The samples printed using the optimal strategy with the highest volumetric energy density (laser power equal to 300 W and scanning speed to 500 mm/s) were characterized by high corrosion resistance in both printing directions (the vertical and horizontal one), the high tensile strength of 334±1 MPa and density of 8.798±0.001 g/cm3. On the other hand, applying the much lower volumetric energy density of 83 J/mm3 results in the preparation of samples with a density of 8.689±0.002 g/cm3 and tensile strength equal to 306±8 MPa. Finally, the possibility of applying Hot Isostatic Pressure technology as a designated post-processing treatment technology was described. It was confirmed that this method could increase the electrical conductivity of printed CuNi3Si1 alloy 4.7 times.